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WO2025215476A1 - Adhésifs comprenant un époxy et polymère (méth)acrylique comprenant un agent de renforcement - Google Patents

Adhésifs comprenant un époxy et polymère (méth)acrylique comprenant un agent de renforcement

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Publication number
WO2025215476A1
WO2025215476A1 PCT/IB2025/053523 IB2025053523W WO2025215476A1 WO 2025215476 A1 WO2025215476 A1 WO 2025215476A1 IB 2025053523 W IB2025053523 W IB 2025053523W WO 2025215476 A1 WO2025215476 A1 WO 2025215476A1
Authority
WO
WIPO (PCT)
Prior art keywords
curable composition
meth
acrylate
composition
acrylic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/IB2025/053523
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English (en)
Inventor
Michael J. Maher
Adam O. Moughton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
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Filing date
Publication date
Application filed by 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of WO2025215476A1 publication Critical patent/WO2025215476A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J163/00—Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins

Definitions

  • a curable composition comprising an epoxy resin, at least 1 wt.% of a toughening agent that is not a polyol; a film forming polymeric material; a photoacid generator; and an ionic liquid that has a melting point less than 100 degrees Celsius and that has an anion selected from SbF 6 ', PF 6 ’, or a mixture thereof.
  • a curable composition comprising an epoxy resin, at least 1 wt.% of a toughening agent that is not a polyol; a photoacid generator; and an ionic liquid that has a melting point less than 100 degrees Celsius and that has an anion selected from SbF 6 ', PF 6 ’, or a mixture thereof.
  • the composition further comprise an epoxy curative, such as a photoacid generator.
  • an epoxy curative such as a photoacid generator.
  • Articles comprising such cured compositions comprising ionic liquid can be removed (e.g., de-bonded) by applying a direct current electric potential across the cured composition.
  • a curable composition comprising an epoxy resin, at least 1 wt.% of a toughening agent that is not a polyol, a film forming polymeric material comprising a (meth)acrylic polymer and an acrylic block copolymer, and a photoacid generator.
  • FIG. 1A is a schematic side view of one exemplary article of the present application.
  • FIG. IB is a schematic side view of a variation on the article in FIG. 1 A;
  • FIG. 1C is a schematic side view of another variation on the article in FIG. 1 A;
  • FIG. 2A is a schematic side view of another exemplary article of the present application.
  • FIG. 2B is a schematic side view of a variation on the article in FIG. 2A.
  • FIG. 3 is a diagram of the testing apparatus used for tensile push out testing.
  • the curable composition comprises an epoxy resin that has at least one epoxy functional group (i.e., oxirane group) per molecule.
  • epoxy functional group i.e., oxirane group
  • oxirane group refers to the following divalent group.
  • the asterisks denote a site of attachment of the oxirane group to another group. If the oxirane group is at the terminal position of the epoxy resin, the oxirane group is typically bonded to a hydrogen atom.
  • This terminal oxirane group is often (and preferably) part of a glycidyl group.
  • the epoxy resin can have a single oxirane group per molecule, it often has at least two oxirane groups per molecule.
  • the epoxy resin can have 1 to 10, 2 to 10, 2 to 6, 2 to 4, or 2 oxirane groups per molecule.
  • the oxirane groups are usually part of a glycidyl group.
  • Epoxy resins can be either a single material or a mixture of different materials selected to provide the desired viscosity characteristics before curing and to provide the desired mechanical properties after curing. If the epoxy resin is a mixture of materials, at least one of the epoxy resins in the mixture is typically selected to have at least two oxirane groups per molecule. For example, a first epoxy resin in the mixture can have two to four oxirane groups and a second epoxy resin in the mixture can have one to four oxirane groups. In some of these examples, the first epoxy resin is a first glycidyl ether with two to four glycidyl groups and the second epoxy resin is a second glycidyl ether with one to four glycidyl groups. In another example, a first epoxy resin in the mixture is a liquid while a second epoxy resin is a solid such as a glassy or brittle solid that is miscible with the first epoxy resin.
  • the portion of the epoxy resin molecule that is not an oxirane group can be aromatic, aliphatic or a combination thereof and can be linear, branched, cyclic, or a combination thereof.
  • the aromatic and aliphatic portions of the epoxy resin can include heteroatoms or other groups that are not reactive with the oxirane groups. That is, the epoxy resin can include halo groups, oxy groups such as in an ether linkage group, carbonyl groups, carbonyloxy groups, and the like.
  • the epoxy resin can also be a silicone-based material such as a polydiorganosiloxane-based material.
  • the epoxy resin includes a glycidyl ether.
  • exemplary glycidyl ethers can be of Formula (V).
  • group R 1 is a p-valent group that is aromatic, aliphatic, or a combination thereof.
  • Group R 1 can be linear, branched, cyclic, or a combination thereof.
  • Group R 1 can optionally include halo groups, oxy groups, carbonyl groups, carbonyloxy groups, and the like.
  • the variable p can be any suitable integer greater than or equal to 1, p is often an integer in the range of 2 to 6 or 2 to 4. In many embodiments, p is equal to 2.
  • the variable p is equal to 2 (i.e., the epoxy resin is a diglycidyl ether) and R 1 includes an alkylene (i.e., an alkylene is a divalent radical of an alkane and can be referred to as an alkane-diyl), heteroalkylene (i.e., a heteroalkylene is a divalent radical of a heteroalkane and can be referred to as a heteroalkane-diyl), arylene (i.e., a divalent radical of an arene compound), or mixture thereof.
  • alkylene i.e., an alkylene is a divalent radical of an alkane and can be referred to as an alkane-diyl
  • heteroalkylene i.e., a heteroalkylene is a divalent radical of a heteroalkane and can be referred to as a heteroalkane-diyl
  • arylene i.e., a divalent radical
  • Suitable alkylene groups often have 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms.
  • Suitable heteroalkylene groups often have 2 to 50 carbon atoms, 2 to 40 carbon atoms, 2 to 30 carbon atoms, 2 to 20 carbon atoms, 2 to 10 carbon atoms, or 2 to 6 carbon atoms.
  • the heteroatoms in the heteroalkylene are often oxy groups.
  • Suitable arylene groups often have 6 to 18 carbon atoms, 6 to 12 carbon atoms, or 6 to 10 carbon atoms.
  • the arylene can be phenylene.
  • Group R 1 can further optionally include halo groups, oxy groups, carbonyl groups, carbonyloxy groups, and the like.
  • Some epoxy resins of Formula (V) are diglycidyl ethers where R 1 includes (a) an arylene group or (b) an arylene group in combination with an alkylene, heteroalkylene, or both.
  • Group R 1 can further include optional groups such as halo groups, oxy groups, carbonyl groups, carbonyloxy groups, and the like.
  • These epoxy resins can be prepared, for example, by reacting an aromatic compound having at least two hydroxyl groups with an excess of epichlorohydrin.
  • useful aromatic compounds having at least two hydroxyl groups include, but are not limited to, resorcinol, catechol, hydroquinone, p,p'-dihydroxydibenzyl, p,p' -dihydroxyphenylsulfone, p,p'-dihydroxybenzophenone, 2,2'- dihydroxyphenyl sulfone, and p,p'-dihydroxybenzophenone.
  • Still other examples include the 2,2', 2,3', 2,4', 3,3', 3,4', and 4,4' isomers of dihydroxy diphenylmethane, dihydroxy diphenyldimethylmethane, dihydroxydiphenylethylmethylmethane, dihydroxydiphenylmethylpropylmethane, dihydroxydiphenylethylphenylmethane, dihydroxydiphenylpropylenphenylmethane, dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane, dihydroxydiphenyltolylmethylmethane, dihydroxydiphenyldicyclohexylmethane, and dihydroxy diphenylcyclohexane.
  • diglycidyl ether epoxy resins of Formula (V) are derived from bisphenol A (i.e., bisphenol A is 4, 4’-dihydroxy diphenylmethane). Examples include, but are not limited to, those available under the trade designation EPON (e.g., EPON 828, EPON 872, EPON 100 IF, EPON 1004, and EPON 2004) from Hexion Specialty Chemicals, Inc.
  • EPON e.g., EPON 828, EPON 872, EPON 100 IF, EPON 1004, and EPON 2004
  • DER e.g., DER 331, DER 332, and DER 336
  • EPICLON e.g., EPICLON 850
  • Other commercially available diglycidyl ether epoxy resins are derived from bisphenol F (i.e., bisphenol F is 2,2’-dihydroxydiphenylmethane).
  • Other epoxy resins of Formula (V) are diglycidyl ethers of a poly(alkylene oxide) diol.
  • epoxy resins can be referred to as diglycidyl ethers of a poly(alkylene glycol) diol.
  • the variable p is equal to 2 and R 4 is a heteroalkylene having oxygen heteroatoms.
  • the poly(alkylene glycol) can be a copolymer or homopolymer. Examples include, but are not limited to, diglycidyl esters of polyethylene oxide) diol, diglycidyl esters of polypropylene oxide) diol, and diglycidyl esters of poly(tetramethylene oxide) diol. Epoxy resins of this type are commercially available from Poly sciences, Inc.
  • Still other epoxy resins of Formula (V) are diglycidyl ethers of an alkane diol (R 1 is an alkylene and the variable p is equal to 2).
  • examples include a diglycidyl ether of 1,4-dimethanol cylco hexyl, diglycidyl ether of 1,4 -butanediol, and diglycidyl ethers of the cycloaliphatic diol formed from a hydrogenated bisphenol A such as those commercially available under the trade designation EPONEX 1510 from Hexion Specialty Chemicals, Inc. (Houston, TX, USA).
  • epoxy resins include silicone resins with at least two glycidyl groups and flame retardant epoxy resins with at least two glycidyl groups (e.g., a brominated bisphenol-type epoxy resin having with at least two glycidyl groups such as that commercially available from Dow Chemical Company (Midland, MI, USA) under the trade designation DER 580).
  • silicone resins with at least two glycidyl groups e.g., a brominated bisphenol-type epoxy resin having with at least two glycidyl groups such as that commercially available from Dow Chemical Company (Midland, MI, USA) under the trade designation DER 580).
  • the epoxy resin is often a mixture of materials.
  • the epoxy resins can be selected to be a mixture that provides the desired viscosity or flow characteristics prior to curing.
  • the mixture can include at least one first epoxy resin that is referred to as a reactive diluent that has a lower viscosity and at least one second epoxy resin that has a higher viscosity.
  • the reactive diluent tends to lower the viscosity of the epoxy resin mixture and often has either a branched backbone that is saturated or a cyclic backbone that is saturated or unsaturated.
  • Examples include, but are not limited to, the diglycidyl ether of resorcinol, the diglycidyl ether of cyclohexane dimethanol, the diglycidyl ether of neopentyl glycol, and the triglycidyl ether of trimethylolpropane.
  • Diglycidyl ethers of cyclohexane dimethanol are commercially available under the trade designation HELOXY MODIFIER 107 from Hexion Specialty Chemicals (Columbus, OH, USA) and under the trade designation EPODIL 757 from Evonik Corporation (Essen, North Rhine -Westphalia, Germany).
  • Other reactive diluents have only one functional group (i.e., oxirane group) such as various monoglycidyl ethers.
  • Some exemplary monoglycidyl ethers include, but are not limited to, alkyl glycidyl ethers with an alkyl group having 1 to 20 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms.
  • Some exemplary monoglycidyl ethers are commercially available under the trade designation EPODIL from Evonik Corporation such as EPODIL 746 (2 -ethylhexyl glycidyl ether) and EPODIL 748 (aliphatic glycidyl ether).
  • the epoxy resins typically have an equivalent weight in a range of 50 to 900 grams/equivalent.
  • the equivalent weight of the epoxy resin refers to the weight of resin in grams that contains one equivalent of epoxy.
  • the equivalent weight is typically no greater than 900, 950, 850, 800 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250 grams/equivalent.
  • the equivalent weight is typically at least 50, 75, 100, 125, 150 grams/equivalent.
  • 100 wt.% of the epoxy resin is of Formula (I), based on the total epoxy resin In other embodiments, at least 95, 90, 85, 80, 75, or 70 wt.% of the epoxy resin is of Formula (I).
  • 100 weight percent of the epoxy resin is a diglycidyl ether (i.e., a compound of Formula (I) with p equal to 2).
  • the epoxy resin is a mixture of compounds of Formula (I) withp equal to 2 and compounds of Formula (I) withp not equal to 2.
  • the amount of the diglycidyl ether is often at least 50, 60, 70, 75, 80 85, 90, 95 wt.% weight, based on the total weight of the epoxy resin.
  • the epoxy resin is free of compounds that have an oxirane group that is not a glycidyl group. If such compounds are included, however, they typically make up less than 30, 20, 10, 5, 2, 1, or 0.5 wt.% based on the total weight of the epoxy resin.
  • the curable composition typically comprises 10 to 50 wt.% epoxy resin based on a total weight of organic components of the curable composition.
  • the amount can be at least 10, 15, 20, 25, 30 wt.%.
  • the curable composition comprises no greater than 50, 45, 40, 35, or 30 wt.%.
  • the curable composition comprises at least 60, 70, 80, 90 wt.% or greater of epoxy resin.
  • the curable composition may be a liquid epoxy resin lacking a film forming polymer.
  • the curable composition typically comprises an epoxy curative.
  • curatives for epoxy resins include nitrogen-containing groups such as amines, amides, ureas, and imidazoles.
  • a common heat activated epoxy curatives include, but are not limited to, dicyandiamide compounds.
  • the epoxy curative is typically a photoacid generator, which can also be referred to as a cationic photoinitiator, is activated to initiate polymerization of the epoxy resin within the curable composition. It is typically selected to be sensitive to (activated by) radiation in the ultraviolet region of the electromagnetic spectrum. For example, the photoacid generator is often selected to be activated at wavelengths less than or equal to 380 nanometers in the ultraviolet region of the electromagnetic spectrum.
  • Suitable photoacid generators are aryl-containing (e.g., bis(aryl-containing)) iodonium salts.
  • aryl-containing iodonium salts such as those with two aryl groups such as bis(4-tert- butylphenyl) iodonium hexafluoroantimonate (available under the trade designation FP5034 from Hampford Research Inc.
  • triaryl sulfonium salts include, but are not limited to, triphenyl sulfonium hexafluoroantimonate (available under the trade designation CT-548 from Chitec Technology Corp.
  • Blends of triaryl sulfonium salts are available from Synasia (Metuchen, NJ, USA) under the trade designation SYNA PI-6992 for hexafluorophosphate salts and under the trade designation SYNA PI-6976 for hexafluoroantimonate salts.
  • Mixtures of triaryl sulfonium salts are commercially available from Aceto Pharma Corporation (Port Washington, NY, USA) under the trade designations UVI-6992 and UVI-6976.
  • the anion of the photoacid generator is selected to be the same as the anion of the ionic liquid included in the curable composition. That is, the anion is selected to be SbF 6 ', PF 6 ’, or a mixture thereof.
  • the epoxy curative comprises a thermal acid generator.
  • Useful classes of TAGs can include, for example, alkylammonium salts of sulfonic acids, such as triethylammonium p- toluenesulfonate (TEAPTS).
  • TEAPTS triethylammonium p- toluenesulfonate
  • Another suitable class of TAGs are cyclic alcohols with adjacent sulfonate leaving groups, such as described in U.S. Pat. No. 6,627,384 (Kim, et al.), incorporated herein by reference.
  • Thermal acid generators include, but are not limited to, products available under the trade designations NACURE, TAG, and K-PURE from King Industries (Norwalk, CT, USA).
  • the epoxy curative(s) (e.g. photoacid generator) is typically used in an amount of at least 0.5 wt.% and up to 5 wt.% based on the total weight of the organic components of the curable composition. In some embodiments, the amount is at least 0.5, 0.6, 0.7, 0.8, 1, 2 wt.%. In some embodiments, the epoxy curative(s) is no greater than 5, 3.5, 3, 2.5, 2, or 1.5 wt.%. based on the total weight of organic components of the curable composition.
  • the curable composition is free of both heat-activated curatives and thermal acid generators for epoxy resins.
  • the curable composition further comprises an ionic liquid.
  • the ionic liquid has a cation that includes either nitrogen or sulfur and an anion that is SbF 6 ', PF 6 ’, or a mixture thereof.
  • the ionic liquid includes at most one aromatic ring.
  • the ionic liquid has a melting point that is less than 100 degrees Celsius. In most embodiments, the melting point is in a range of -45 to 100 degrees Celsius. The melting point can be determined according to ASTM method E794-06 (reapproved 2018).
  • the ionic liquid is an ammonium salt of Formula (VI), a sulfonium salt of Formula (VII), an imidazolium salt of Formula (VIII), pyridinium salt of Formula (IX), pyrrolidinium salt of Formula (X).
  • each R 20 , R 21 , R 22 , R 23 , and R 24 is independently an alkyl, a hydroxy substituted alkyl, or an ether-containing group of formula -(R 30 -O) y -R 31 where R 30 is an alkylene, R 31 is an alkyl, and y is an integer in a range of 1 to 10.
  • Any of the alkyl and/or alkylene groups can have 1 to 20 carbon atoms such as at least 1, at least 2, at least 3, or at least 5 and up to 20, up to 18, up to 16, up to 12, up to 10, up to 8, up to 6, up to 4, or up to 3 carbon atoms.
  • the alkylene often has 1 to 3 carbon atoms.
  • each R 20 , R 21 , R 22 , R 23 , and R 24 is an alkyl such as methyl or ethyl.
  • Each X" is either SbF 6 ' or PF 6 ’.
  • the anion (X‘) of the ionic liquid is selected to be identical to the anion used in the photoacid generator included in the curable composition.
  • the amount of the ionic liquid in the curable composition is typically in a range of 0.5 to 20 weight percent based on a total weight of the curable composition. The amount can be at least 0.5, 1, 2, 3, 4, 5 wt.%. In some embodiments, the amount of ionic liquid is no greater than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 wt.%.
  • the amount of the ionic liquid relative to the sum of ionic liquid and epoxy resin is typically in a range of 0.5 to 20 weight percent based on a total weight of the curable composition.
  • the amount can be at least 0.5, 1, 2, 3, 4, 5 wt.%.
  • the amount of ionic liquid is no greater than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, or 5 wt.%.
  • the ionic liquid facilitates the debonding of the cured adhesive from a substrate at the end of the useful life of an article containing the cured adhesive.
  • the ionic liquid facilitates the removal of the cured adhesive from a metal-containing substrate such as, for example, an electronic component. This allows the metal substate (e.g., electronic component) to be reused at the end of the useful life of an article.
  • the Tensile Push Out or Dynamic Shear Peak Stress reduces by at least 50, 60, 70, 80, 90 or 95% after 2 min of 50 volts.
  • the curable composition can optionally include a polyol.
  • the polyol is typically a polymeric material and is often a polyether polyol, polyester polyol, (meth)acrylic polyol, or a polycaprolactam polyol.
  • the polyols can function as a toughening agent and/or can retard the curing reaction of the curable composition.
  • a toughening agent the presence of the polyol can increase the shear strength of the final cured composition. That is, the polyols can decrease the crosslink density and increase the elongation of the cured composition.
  • some polyols such as polyether polyols tend to increase the "open time" of the curable composition.
  • the term "open time” refers to the time after the curable composition has exposed to ultraviolet and/or visible radiation, during which the curable composition remains sufficiently uncured for bonding to another surface.
  • the open time of the curable composition is desirably at least 2 minutes after exposure to ultraviolet and/or visible radiation.
  • UV-A radiation is provided by LED lights with an energy dose of at least 3 or 6 ranging up to 9 J/cm 2 . If one or both substrates that are being bonded together are transmissive for the radiation to which the curable composition is exposed, however, the open time is of no relevance because in that case the exposure to the radiation can be effected through the transmitting substrate after both substrates have been attached to each other through the blended filament composition. When both substrates of the assembly are opaque, the blended filament composition is often exposed to ultraviolet radiation prior to attaching the second substrate thereto.
  • the polyol is a polyether polyol having at least two or at least 3 hydroxyl groups.
  • polyether polyols suitable for toughening agents may also comprise a single hydroxyl group,
  • the polyether polyols are typically polyether diols such as polyoxyalkylene glycols.
  • polyoxyalkylene glycols include, but are not limited to, polyoxyethylene glycols, polyoxypropylene glycols, and polyoxybutylene glycols (which can also be referred to as poly(tetramethylene oxide) glycols or poly(tetrahydrofuran) glycol).
  • Other suitable polyether polyols are polyether triols such as polyoxyalkylene triols. These triols can be derived from glycerol. Examples include, but are not limited to, polyoxyethylene triol and polyoxypropylene triol.
  • the polyether polyol is typically miscible with or forms a macroscopically stable mixture with the other curable components such as the epoxy resin and any optional film-forming resin.
  • Suitable polytetramethylene oxide glycols include, for example, those commercially available under the trade designation POLYMEG from LyondellBasell, Inc. (Jackson, TN, USA), under the trade designation TERATH ANE from Invista (Newark, DE, USA), and under the trade designation POLYTHF from BASF Corp. (Charlotte, NC, USA).
  • Suitable polyoxypropylene polyols include those commercially available under the trade designation ARCOL from Bayer Material Science (Los Angeles, CA, USA).
  • polyether polyols are commercially available under the trade designation VORANOL from Dow Chemical Company (Midland, MI, USA) and under the trade designation DESMOPHEN from Covestro (Leverkusen, Germany) such as DESMOPHEN 550U, 1600U, 1900U, and 1950U. Additional polyether polyols are available under the trade designation CARBOWAX from Dow Chemical Company.
  • Suitable polyester polyols are commercially available under the trade designation DESMOPHEN from Covestro (Leverkusen, Germany) such as DEMMOPHEN 631 A, 650A, 651A, 670A, 680, 110, and 1150.
  • DESMOPHEN from Covestro
  • Other polyester polyols that are available under the trade designation DYNAPOL from Evonik Corporation (Essen, North Rhine -Westphalia, Germany) that can be linear and saturated, semi-crystalline or amorphous.
  • Suitable (meth)acrylate-based polyols are commercially available under the trade designation DESMOPHEN from Covestro (Leverkusen, Germany) such as DESMOPHEN A160SN, A575, and A450BA/A.
  • Suitable polycaprolactone polyols are commercially available from Dow Chemical Company (Midland, MI, USA) under the trade designation TONE and from Ingevity (North Charleston, SC, USA) under the trade designation CAPA.
  • the polyols can be characterized by their hydroxyl number, which refers to milligrams of KOH per gram of hydroxyl-containing material. This can be determined, for example, by adding an excess of an acidic material that reacts with the polyol and then by back titrating the remaining acidic material with a base to determine the amount of hydroxyl groups per gram of the polyol. The amount of hydroxyl groups is reported as though they were from the basic material KOH.
  • the hydroxyl number (mg KOH per gram of polyol) is usually at least 10, 25, 50, 75, 100, 125, 150, 175, or 200. The hydroxyl number is typically no greater than 700, 650, 600, 550, 500, 450, 400, 350, 300, or 250.
  • the polyol is a liquid at room temperature. In other embodiments, the polyether polyol is a liquid at temperatures above 40°C.
  • the polyols that are not liquids at room temperature are often soluble in the other curable components or can be dissolved, if necessary, in an optional organic solvent.
  • the weight average molecular weight can be up no greater than 50,000; 40,000; 20,000; 10,000; or 5,000 Daltons. In some embodiments, the weight average molecular weight is typically at least 100, 500, 750, 1,000; 1,500; or 2,000 Daltons.
  • the amount of the optional polyol is zero or at least 1, 2, 3, 4, 5, 8, or 10 wt.%. based on a total weight of the organic components of the curable composition.
  • the amount the polyether polyol is typically no greater than 30, 25, 20, 18, 15, 12, or 10 wt.%.
  • the curable composition comprises a toughening agent that is not a polyol.
  • the toughening agent typically comprises an elastomeric polymer, a (e.g. low Tg) thermoplastic polymer, or a combination thereof. In typical embodiments, at least a portion of the toughening agent is phase separated within the epoxy resin.
  • the toughening agent comprises a C4-C5 conjugated diene, most commonly isoprene (i.e. “I”) or butadiene (i.e. “B”).
  • the conjugated diene may be hydrogenated.
  • the block copolymer toughening agent may further comprising polystyrene (i.e. “S”) and/or an acrylic block, such as poly(methyl methacrylate) (i.e. “M”).
  • S polystyrene
  • M acrylic block, such as poly(methyl methacrylate)
  • SIS, SBS, and MBS block copolymers are commercially available. Examples of such are further described in the forthcoming examples.
  • the toughening agent comprises polymeric particles.
  • the physical form of the toughening agent is particles at a temperature of 25°C.
  • the toughening agent particles may have a mean or median particle size of less than 500, 250, 100 or 50 microns. In some embodiments, the toughening agent particles may have a mean or median particle size of less than 1 micron or 500 nm.
  • Various particles comprising an acrylic polymer and/or a C4-C5 conjugated diene polymer (e.g. butadiene) polymer are commercially available as powders (such as described in the forthcoming examples).
  • toughening agent particles are also available pre-dispersed in an epoxy resin.
  • the toughening agent may be characterized as a core-shell polymer.
  • acrylic core-shell polymers are commercially available.
  • the core is typically an polymer having a glass transition temperature below 0°C, such as polybutyl acrylate, polyisooctyl acrylate, polybutadiene-polystyrene.
  • the shell comprises an acrylic polymer having a glass transition temperature above 25°C, such as polymethylmethacrylate.
  • Commercially available core-shell acrylic polymers include those available under the trade designations PARALOIDTM KM-330 from Dow Chemical
  • core-shell polymers comprise butadiene.
  • methylmethacrylate-butadiene- styrene core-shell toughening agent particle are available under the tradename ClearstrengthTM XT100 from Arkema, Colombes, France and from Dow Chemical under the trade designation PARALOIDTM EXL-2650 J.
  • HYCAR carboxyl-terminated butadiene acrylonitrile compounds available under the trade designations HYCAR (e.g., HYCAR 1300X8, HYCAR 1300X13, and HYCAR 1300X17) from Lubrizol Advanced Materials, Inc. (Cleveland, Ohio) and from Dow Chemical (Midland, MI).
  • HYCAR carboxyl-terminated butadiene acrylonitrile compounds available under the trade designations HYCAR (e.g., HYCAR 1300X8, HYCAR 1300X13, and HYCAR 1300X17) from Lubrizol Advanced Materials, Inc. (Cleveland, Ohio) and from Dow Chemical (Midland, MI).
  • toughening agents comprise toughening particles, such as (e.g. core shell) polymer particles comprising styrene-butadiene rubber, polybutadiene rubber or poly dimethylsiloxane.
  • the polymer particles are pre-dispersed in an epoxy resin.
  • the amount of (e.g. core shell or polydimethylsiloxane) polymer particles pre-dispersed in an epoxy resin typically ranges from at least 20 or 25 wt.% ranging up to 40 or 45 wt.%.
  • Such toughening agents are commercially available from Kaneka as trade designation Kane AceTM MX and from Evonik as trade designation ALBIDUR EP 2240 A.
  • the curable composition comprise a toughening agent that is liquid polymer at 25°C.
  • the liquid polymer comprises an optionally hydrogenated C4- C5 conjugated diene and typically functional groups.
  • Functional groups include for example hydroxyl, carboy, phenol, epoxy, mercaptan, and (methjacrylate.
  • the toughening agents that are solid at 25°C may also comprise such functional groups.
  • a hydroxyl-functional polybutadiene is reacted with a compound comprising an isocyanate and an acrylate group to produce a polybutadiene toughening agent comprising an acrylate and urethane linking group.
  • the polybutadiene may be hydrogenated.
  • the curable compositions comprise at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt.% of a toughening agent that is not a polyol, based on the total wt.% solids of the curable composition.
  • the amount of toughening agent that is not a polyol is no greater than 30, 25, 20, 15 or 10 wt.% of the curable composition.
  • the film forming polymeric material typically provides a dimensionally stable layer of curable composition that can be wound into a roll or die cut.
  • the film forming polymeric material is typically an elastomeric polymer, a thermoplastic polymer, or a combination thereof.
  • Common polymers include polyurethanes, rubber (e.g. natural rubber, synthetic rubber such as butyl rubber, isobutyl, nitrile or butadiene rubbers), polyolefins, fluoropolymers, silicones, and styrenic block copolymers.
  • Styrenic block copolymers comprise one or more styrenic end blocks and an unsaturated, partly hydrogenated or fully hydrogenated polydiene block, most commonly polybutadiene, polyisoprene, or poly(iso)butylene.
  • Other common organic polymers include polyolefins (e.g.
  • vinyl polymers including ethylene vinyl acetate; poly(vinyl alcohol, poly(vinyl)acetate, poly(vinyl chloride), polyvinyl acetal such as
  • the film forming polymeric material comprises two or more different film forming polymeric materials.
  • the film forming polymeric material may comprise two different (meth)acrylic polymers such as a random (meth)acrylic copolymer and a (meth)acrylic block copolymer,
  • the film forming polymer material has a Tg less than 20°C, as previously described. In other embodiments, the film forming polymer material has a Tg greater than 20, 25, 30, 40, 50, or 60°C; yet the uncured epoxy resin and/or optional polyol functions as a plasticizer such that the film forming polymeric material together with the uncured epoxy resin has a Tg less than 20°C, as previously described.
  • the film forming polymer material comprises polyurethane.
  • Polyurethanes are prepared from at least one isocyanate including a diisocyanate and at least one polyol including a diol; as well as other components such as diol chain extenders.
  • Various polyols including polyester and polyether polyols are subsequently described.
  • the diisocyanate can be monomeric, oligomeric or polymeric.
  • An example of a suitable diisocyanate includes a diisocyanate having the structure:
  • R6 is substituted or unsubstituted C1-C40 alkylene, C2-C40 alkenylene, C4-C20 arylene, C4-C20 arylene-Ci-C4o alkylene-C4-C2o arylene, C4-C20 cycloalkylene, and C4-C20 aralkylene.
  • the diisocyanate is chosen from dicyclohexylmethane-4,4’ -diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 1,4-phenylene diisocyanate, 1,3 -phenylene diisocyanate, m- xylylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, poly(hexamethylene diisocyanate), 1,4-cyclohexylene diisocyanate, 4-chloro-6-methyl- 1,3 -phenylene diisocyanate, 4,4’- diphenylmethane diisocyanate, 2,4 ’-diphenylmethane diisocyanate, 1,4-diisocyanatobutane, 1,8- diisocyanatooctane, 2,5-toluene diisocyanate, methylene bis
  • the diisocyanate may be a chain extended diisocyanate, i.e. the reaction product of a diisocyanate and a dihydroxyl terminated oligomer or polymer, e.g. a dihydroxyl terminated, linear oligomer or polymer.
  • the polyurethane is thermoplastic.
  • Various thermoplastic polyurethanes are commercially available, such as the exemplified thermoplastic polyurethane.
  • the film forming polymer material comprises polyester.
  • Polyesters are prepared by reacting dicarboxylic acids (or their diester equivalent) and polyols (e.g. diols). Various polyols including polyester and polyether polyols are subsequently described.
  • Examples o f aliphatic dicarboxylic acids are saturated aliphatic dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, a-methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid or dimerized linoleic acid; or unsaturated aliphatic polycarboxylic acids, such as maleic acid, fumaric acid, mesaconic acid, citraconic acid, glutaconic acid or itaconic acid, and also possible anhydrides of these acids.
  • Aromatic dicarboxylic acids may also be utilized as well as blends of dicarboxylic acids.
  • Illustrative tape composition comprises polyester and epoxy resin are described in US 6,254,954; incorporated herein by reference.
  • the film forming polymeric material comprises polyvinyl acetal.
  • the polyvinyl acetal resin generally has repeating units represented by wherein Ri is hydrogen or a C1-C7 alkyl group.
  • Polyvinyl acetal resin is obtained, for example, by reacting polyvinyl alcohol with aldehyde, as known in the art. (See for examples WO2016/094277)
  • the content of polyvinyl acetal typically ranges from 65 wt-% up to 90 wt-% of the polyvinyl acetal (e.g. butyral) resin. In some embodiments, the content of polyvinyl acetal (e.g. butyral) ranges from about 70 or 75 up to 80 or 85 wt-%.
  • the content of polyvinyl alcohol typically ranges from about 10 to 30 wt-% of the polyvinyl acetal (e.g. butyral) resin. In some embodiments, the content of polyvinyl alcohol ranges from about 15 to 25 wt-%.
  • the content of polyvinyl acetate of the polyvinyl acetal resin can be zero or range from 1 to 8 wt-% of the polyvinyl acetal (e.g. butyral) resin. In some embodiments, the content of polyvinyl acetate ranges from about 1 to 5 wt-%.
  • the alkyl residue of aldehyde comprises 1 to 7 carbon atoms.
  • butylaldehyde also known as butanal is most commonly utilized.
  • Polyvinyl butyral (“PVB”) resin is commercially available from Kuraray under the trade designation “MowitalTM” and Solutia under the trade designation “ButvarTM”.
  • the weight average molecular weight (M w ) of such other film forming polymers is typically with the same range as previously described for the (meth)acrylic -based triblock copolymer A-B-A. In some embodiments, the weight average molecular weight (M w ) of such other film forming polymers is greater than 50,000; 55,000, or 60,000 Daltons.
  • the film forming polymeric material comprises a styrenic block copolymers.
  • Styrenic block copolymers can have various structures, including diblock (A-B), triblock (A-B-A), multiblock (A-B-A-B-A), star-shaped ((A-B)n), radial ((A-B)n-X), and tapered; wherein A is the polystyrene block and B is the unsaturated or saturated polydiene block.
  • the polydiene block may be isoprene, butadiene, ethylene/propylene, or ethylene butylene.
  • the styrene content is typically at least 15, 20, 25 or 30 wt.%, of the styrenic bock copolymer. In some embodiments, the styrene content of the styrenic bock copolymer is no greater than 50, 45, 40, 35, or 30 wt.%. Styrenic block copolymers typically have a molecular weight of at least 50,000 or 100,000 g/mol ranging up to 300,000 g/mol or greater.
  • the diblock content can range from 0% to 50% wt.% of the styrene block copolymer. In some embodiments, the styrene block copolymer comprises triblock and diblock. The amount of diblock may be at least 10, 20, 30, 40 or 50 wt.% of the styrene block copolymer.
  • the curable composition (e.g. of the first article) comprises greater than 30. 45, 40, 45, 50, 55, 60, 65. 70, 75, 80, 85, or 90 weight percent of film forming poly meric materials based on a total weight of resin components in the curable composition. In some embodiments, the curable composition comprises no greater than 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, or 40 weight percent of otter film forming polymeric materials.
  • the curable composition may-lack typically comprises (meth)acry lie -based polymer(s) in combination with another film forming polymeric material such as an acrylic block copolymer, a styrenic block copolymer, or polyvinyl butyral polymer.
  • the amount of other film forming polymeric material is typically at least 2, 3, 4, or 5 wt.% and typically no greater than 20, 25 or 10 wt.% of the total composition.
  • the curable liquid epoxy resin composition may lack a film forming polymeric material or may comprise such material in an insufficient concentration to form a film.
  • the curable composition comprises a (meth)acrylic polymer
  • the polymerizable composition used to form the (meth)acrylic copolymer typically comprise alkyl (meth)acrylate monomer(s).
  • the (meth)acrylic copolymer comprise polymerized units of alkyl (meth)acrylate monomer(s).
  • any suitable alkyl (meth)acrylate or mixture of alkyl (meth)acrylates can be included in the polymerizable composition.
  • the choice of the alkyl (meth)acrylate can influence the glass transition temperature of the (meth)acrylic copolymer.
  • the monomers are selected so that the glass transition temperature of the (meth)acrylic copolymer is no greater than 40, 30, 20° C.
  • the glass transition temperature is often no greater than 15, 10, or 5 ° C.
  • the (meth)acrylic polymer together with the uncured epoxy resin typically has a Tg no greater than 20, 15, 10, or 5° C.
  • Some alkyl (meth)acrylate monomers are classified as low T g monomers based on the glass transition temperature of their corresponding homopolymers.
  • the low T g monomers as measured from the corresponding homopolymers, often have a T g no greater than 20, 10, 0, or -10° C.
  • Other alkyl (meth)acrylates are classified as high T g monomers based on the glass transition temperature of the corresponding homopolymers.
  • the high T g monomers, as measured from the corresponding homopolymers often have a T g greater than 30°C, 40 °C, or 50 °C.
  • the glass transition temperature can be measured using Dynamic Mechanical Analysis (DMA) as described in the Example section.
  • DMA Dynamic Mechanical Analysis
  • Suitable low T g alkyl (meth)acrylate monomers include, but are not limited to, non-tertiary alkyl acrylates but can be an alkyl (meth)acrylate having a linear alkyl group with at least 1, 2, 4 carbon atoms.
  • alkyl (meth)acrylates include, but are not limited to, n-butyl acrylate, n- butyl methacrylate, isobutyl acrylate, sec-butyl acrylate, n-pentyl acrylate, 2-methylbutyl acrylate, n- hexyl acrylate, cyclohexyl acrylate, 4-methyl-2 -pentyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, isoamyl acrylate, and combinations thereof.
  • the alkyl (meth)acrylate monomers are typically selected to include at least one low T g monomer such as those that have a T g no greater than -10 degrees Celsius when measured as a homopolymer.
  • Such alkyl monomers include, but are not limited to, 2-ethylhexyl acrylate, isooctyl acrylate, n-butyl acrylate, 2-methylbutyl acrylate, iso-octyl acrylate, 2-octyl acrylate, and combinations thereof.
  • Some suitable high T g alkyl (meth)acrylate monomers include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, isobomyl (meth)acrylate, stearyl (meth)acrylate, 3,3,5 trimethylcyclohexyl (meth)acrylate, and combinations thereof.
  • the alkyl (meth)acrylate is selected to have an alkyl group with no greater than 8 carbon atoms, no greater than 7 carbon atoms, no greater than 6 carbon atoms, no greater than 5 carbon atoms, or no greater than 4 carbon atoms to enhance miscibility of the (meth)acrylic copolymer with other components of the curable composition.
  • the (meth)acrylic copolymer comprises polymerized units of alkyl (meth)acrylate monomer(s) in an amount of at least 30, 35, 40, 45, 50 wt.% based on the total weight of the (meth)acrylic copolymer. In some embodiments, the (meth)acrylic copolymer comprises polymerized units of alkyl (meth)acrylate monomer in an amount 30, 35, 40, 45, 50 wt.% based on the total weight of the (meth)acrylic copolymer.
  • the (meth)acrylic copolymer comprises polymerized units of alkyl (meth)acrylate monomer(s) in an amount no greater than 99, 98, 87, 96, 95, 94, 93, 92, 91 or 90 wt.% based on the total weight of the (meth)acrylic copolymer. In some embodiments, the (meth)acrylic copolymer comprises polymerized units of alkyl (meth)acrylate monomer(s) in an amount no greater than 85, 80, 75, 70, 65, or 60 wt.% based on the total weight of the (meth)acrylic copolymer.
  • the polymerizable composition used to form the (meth)acrylic copolymer may comprise a polar monomer.
  • the (meth)acrylic copolymer may comprise polymerized units of polar monomer(s).
  • the polar monomer contains an ethylenically unsaturated group plus a polar group.
  • the ethylenically unsaturated group is either a vinyl or (meth)acryloyl group.
  • Suitable polar groups can be a hydroxyl group, an ether (or polyether) group, or an epoxy group.
  • the polar monomer is typically not an acidic monomer because these monomers tend to be reactive with the epoxy resin in the curable composition. Further, the polar monomer is typically not a nitrogen-containing monomer because of the reactivity of these groups with epoxy resins.
  • the (meth)acrylic copolymer is free of polymerized acidic polar monomers or contains less than 0.5, 0.2, 0.1, 0.05, 0.02, or 0.01 wt.% of polymerized units of polar monomers based on the total weight of the (meth)acrylic copolymer .
  • the (meth)acrylic copolymer is also typically free of polymerized units of nitrogen-containing polar monomers or contains less than 0.5, 0.2, 0.1, 0.05, 0.02, or 0.01 wt.% of polymerized units of nitrogen-containing polar monomers based on the total weight of the(meth)acrylic copolymer.
  • Exemplary polar monomers with a hydroxyl group include, but are not limited to, hydroxyalkyl (meth)acrylates (e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3 -hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate), ethoxylated hydroxyethyl (meth)acrylate, and aryloxy substituted hydroxyalkyl (meth)acrylates (e.g., 2 -hydroxy-2 -phenoxypropyl (meth)acrylate).
  • hydroxyalkyl (meth)acrylates e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3 -hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate
  • ethoxylated hydroxyethyl (meth)acrylate e.g., 2-hydroxy-2 -phen
  • Exemplary ether-containing polar monomers include those selected from 2 -ethoxy ethoxyethyl (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, di(ethylene glycol)-2-ethylhexyl-ether acrylate, ethylene glycol-methyl ether acrylate, and combinations thereof.
  • Suitable ether-containing (meth)acrylate monomers usually have a number average molecular weight less than 300 Daltons, less than 275 Daltons, or less than 250 Daltons.
  • the amount of polymerized units of non-acidic and non-nitrogen-containing polar monomers of the (meth)acrylic copolymer can be 0 or at least 0.5, 1, 2, 3, 5, 10, 15 wt.% of the (meth)acrylic copolymer. In some embodiments, the (meth)acrylic copolymer comprises no greater than 30, 25, 20, 15,10, 5 wt.% of polymerized units non-acidic and non-nitrogen-containing polar monomers.
  • the curable composition comprises a (meth)acrylic copolymer that is formed from a polymerizable composition that comprises at least one (meth)acryl macromer.
  • the (meth)acryl copolymer comprises polymerized units of one or more (meth)acryl macromers.
  • a macromer comprises repeat units.
  • the repeat units typically comprise oxygen moieties.
  • the oxygen moieties are ether moieties or ester moieties.
  • the repeat units are selected from polyester and polyether.
  • the (meth)acryl macromer comprises a terminal -OR 1 group wherein R 1 is hydrogen or a hydrocarbon group.
  • the hydrocarbon group is typically a Cl to C24 hydrocarbon group.
  • the hydrocarbon group is a C1-C4 hydrocarbon group.
  • the hydrocarbon group is methyl, or in other words the (meth)acryl macromer comprises a terminal methoxy group.
  • the terminal methoxy group further comprise a - CH2CH2- space group between the methoxy end group and oxygen atoms of the poly ether.
  • the hydrocarbon group has no greater than 22, 20, 18, 16, or 15 carbon atoms.
  • the hydrocarbon group may be aliphatic, e.g. alkyl. In other embodiments, the hydrocarbon group may be aromatic, e.g. aryl, alkaryl, or aralkyl.
  • An example of a macromer wherein R 1 is aromatic is nonyl phenoxy PEG acrylate (CAS No. 50974-47-5), molecular weight is 626 Daltons (Da). Macromers with aromatic terminal groups may be more compatible with aromatic epoxy resins.
  • the number average molecular weight of the (meth)acryl macromer is typically least 300 or 400 Daltons (Da).
  • the number average molecular weight is typically no greater than 10,000; 9,000; 8,000; 7,000; 6,000; or 5,000 Da.
  • the number average molecular weight is at least 500, 600, 700, 800, 900, 1000 Da.
  • the number average molecular weight is no greater than 4,000; 3,000; 2,500; 2,000, or 1,500 Da.
  • the (meth)acryl macromer is a poly ether macromer.
  • the polyether (meth)acryl macromer typically has Formula A:
  • R 1 is hydrogen or a Cl to C24 hydrocarbon group, as previously described. In some embodiments, R 1 is a C5 to C24 hydrocarbon group.
  • R 2 is hydrogen or methyl.
  • R 3 is independently a straight chain or branched alkylene having 2 to 12 carbon atoms. In some embodiments, R 3 is a C5 to C24 hydrocarbon group.
  • R 4 is oxygen or in other words the macromer is a (meth)acrylate macromer. In some embodiments, and R 4 is NH or in other words the macromer is a (meth)acrylamide monomer. In some embodiments, R 4 further comprises other linking groups between the (meth)acryl terminal group and the repeat units.
  • the number of repeat units, p averages at least 2.
  • the number of repeat units, p has an average value such that the (meth)acryl macromer has a number average molecular weight in the ranges previously described.
  • R 3 comprises no greater than 10, 8, 6 or 4 carbon atoms.
  • the group -(R 3 -O) p - is poly(tetramethylene oxide), polypropylene oxide), poly (propylene oxide)-co-poly(ethylene oxide), or polyethylene oxide) group.
  • the repeating units may form a homopolymer or copolymer.
  • the copolymer may be random or a block copolymer.
  • Polyether (meth)acrylamide macromers as known for example from US2023/0416574; incorporated herein by reference.
  • a representative macromer is depicted as follows:
  • polyether (meth)acrylic macromers include BISOMER PPA6 (polypropylene glycol) acrylate reported to have a number average molecular weight of 420 Daltons), BISOMER PEM63P HD (a mixture of polyethylene glycol) methacrylate and polypropylene glycol) reported to have a number average molecular weight of 524 Daltons), BISOMER PPM5 LI polypropylene glycol) methacrylate reported to have a number average molecular weight of 376 Daltons), BISOMER PEM6 LD (poly(ethylene glycol) methacrylate reported to have a number average molecular weight of 350 Daltons).
  • BISOMER PPA6 polypropylene glycol) acrylate reported to have a number average molecular weight of 420 Daltons
  • BISOMER PEM63P HD a mixture of polyethylene glycol) methacrylate and polypropylene glycol
  • BISOMER PPM5 LI polypropylene glycol) methacrylate
  • R 3 comprises at least 4 carbon atoms, such as in the case of poly(tetrahydrofuran) macromers.
  • Poly(tetrahydrofuran) macromers are described in WO2022/043784; incorporated herein by reference.
  • a representative macromer is depicted as follows:
  • R 2 is hydrogen or methyl
  • R 5 is independently alkylene having 2 to 12 carbon atoms
  • R 6 is independently alkylene having 2 to 24 carbon atoms, and n is the number of repeat units.
  • the alkylene groups can be straight-chained or branched.
  • R 6 has no greater than 20, 18, 16, 14, 12, or 10 carbon atoms.
  • the number of repeat units, n averages at least 2.
  • the number of repeat units, n has an average value such that the (meth)acryl macromer has a number average molecular weight in the ranges previously described.
  • Representative macromers include hydroxyethylcaprolactone acrylate (HECLA), wherein R 2 is hydrogen, R 5 is ethylene, R 6 is C5, and n averages 2.8.
  • Other representative monomers include PEDL-A and PLA-MA described in the forthcoming examples.
  • Polyester (meth)acrylic macromers can be prepared by any suitable method.
  • the polyester (meth)acrylic macromers are prepared by reacting dicarboxylic acids (or their diester equivalent) and diols.
  • the acid terminal group of the polyester backbone can then be reacted with a (e.g. hydroxyl-functional) (meth)acrylate compound.
  • Example s o f aliphatic dicarboxylic acids are saturated aliphatic dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, a-methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid or dimerized linoleic acid; or unsaturated aliphatic polycarboxylic acids, such as maleic acid, fumaric acid, mesaconic acid, citraconic acid, glutaconic acid or itaconic acid, and also possible anhydrides of these acids. Blends of acids may be used.
  • Suitable aliphatic dials are alkylenediols, such as ethylene glycol, propane-1, 2-diol, propane- 1,3 -diol, butane- 1,4-diol, pentane-l,5-diol, neopentyl glycol, hexane- 1,6-diol, octane- 1,8-diol, decane- 1,10- diol or dodecane-l,12-diol.
  • alkylenediols such as ethylene glycol, propane-1, 2-diol, propane- 1,3 -diol, butane- 1,4-diol, pentane-l,5-diol, neopentyl glycol, hexane- 1,6-diol, octane- 1,8-diol, decane- 1,10- diol or dodecane-l
  • Suitable cycloaliphatic dials are 1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, 1,4- cyclohexanedimethanol, bis-4-( hydroxycyclohexy 1)- methane or 2,2-bis-( 4- hydroxycyclohexyl)-propane.
  • Long chain diols including poly(oxyalkylene) glycols in which the alkylene group contains from 2 to 9 carbon atoms or 2 to 4 carbon atoms may also be used. Blends of diols may also be used.
  • the hydroxyl-functional (meth)acryl macromer has a hydroxyl value (as determined by ASTM E 1899; August 2023) of at least 75, 100, 125, or 150 mg KOH/g. In some embodiments, the hydroxyl value is no greater than 350, 300, 250, 200, or 150 mg KOH/g. In some embodiments, the hydroxyl-functional (meth)acryl macromer has an acid value (as determined by ASTM E 1045; January 2006) of at least 1, 2, 3, 4, or 5 mg KOH/g. In some embodiments, the acid value is no greater than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0 mg KOH/g.
  • hydroxyl-functional (meth)acryl macromers include BISOMER PPA6 (poly(propylene glycol) acrylate reported to have a number average molecular weight of 420 Daltons), BISOMER PEM63P HD (a mixture of poly(ethylene glycol) methacrylate and poly(propylene glycol) reported to have a number average molecular weight of 524 Daltons), BISOMER PPM5 LI (poly(propylene glycol) methacrylate reported to have a number average molecular weight of 376 Daltons), BISOMER PEM6 LD (poly(ethylene glycol) methacrylate reported to have a number average molecular weight of 350 Daltons).
  • BISOMER PPA6 poly(propylene glycol) acrylate reported to have a number average molecular weight of 420 Daltons
  • BISOMER PEM63P HD a mixture of poly(ethylene glycol) methacrylate and poly(propylene glycol) reported to have a number average mole
  • Other (meth)acrylate macromers can be obtained from Millipore Sigma (Burlington, Massachusetts, USA) include poly (ethylene glycol) phenyl ether acrylate having a number average molecular weight of 324 Da, methoxy polyethylene glycol 550 acrylate (MPEG550A) having a number average molecular weight of 550 Da, polyethylene glycol) methyl ether acrylate having a number average molecular weight of 480 Da, polyethylene glycol) methyl ether acrylate having a number average molecular weight of 2,000 Da, poly(ethylene glycol) methyl ether acrylate having a number average molecular weight of 5,000 Da, and poly (propylene glycol) acrylate having a number average molecular weight of 475 Da.
  • MPEG550A methoxy polyethylene glycol 550 acrylate
  • MPEG550A methoxy polyethylene glycol 550 acrylate
  • (meth)acrylate macromers are available under the tradename BISOMER from Geo Specialty Chemicals, Ambler, PA, such as BISOMER MPEG350MA (methoxy poly (ethylene glycol) methacrylate) reported to have a number average molecular weight of 430 Daltons), and BISOMER MPEG550MA (methoxy polyethylene glycol) methacrylate reported to have a number average molecular weight of 628 Daltons).
  • BISOMER MPEG350MA methoxy poly (ethylene glycol) methacrylate
  • BISOMER MPEG550MA methoxy polyethylene glycol methacrylate reported to have a number average molecular weight of 628 Daltons
  • MIRAMER M193 MPEG600MA methoxy poly(ethylene glycol) methacrylate reported to have a number average molecular weight of 668 Daltons
  • MIRAMER M164 nonyl phenol polyethylene glycol) acrylate reported to have a number average molecular weight of 450 Daltons
  • MIRAMER M1602 nonyl phenol polyethylene glycol) acrylate reported to have a number average molecular weight of 390 Daltons
  • MIRAMER M166 nonyl phenol poly(ethylene glycol) acrylate reported to have a number average molecular weight of 626 Daltons.
  • Still other suitable (meth)acrylate macromers are available from Sans Esters Corporation, New York, NY such as MPEG-A400 (methoxy polyethylene glycol) acrylate reported to have a number average molecular weight of 400 Daltons), and MPEG-A550 (methoxy polyethylene glycol) acrylate reported to have a number average molecular weight of 550 Daltons.
  • MPEG-A400 methoxy polyethylene glycol
  • MPEG-A550 methoxy polyethylene glycol
  • the curable composition comprises polymerized units of (meth)acryl macromer in an amount of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wt.% based on the total weight of the (meth)acrylic copolymer. In typical embodiments, the curable composition comprises no greater than 30, 25, or 20 wt.% of polymerized units of (meth)acryl macromer. In some embodiments, the curable composition comprises no greater than 19, 18, 17, 16, 15, 14, 13, 12, 11, 10 wt.% of polymerized units of (meth)acryl macromer.
  • the inclusion of (meth)acryl macromers, as described herein, can increase the peak stress of the cured composition when evaluated according to the Tensile Push Out Test (described in the examples).
  • the Tensile Push Out peak stress is at least 1.0, 1.5, 2.0, 2.25, 2.50, or 2.75 MPa.
  • the Tensile Push Out peak stress is no greater than 3, 4, 5, 6 MPa.
  • the inclusion of (meth)acrylic macromer can decrease the peak stress of the cured composition when evaluated according to the Dynamic Shear Test (described in the examples).
  • the Dynamic Shear peak stress is less than 10, 9, 8, 7, 6, 5, 4, 3, or 2.0 MPa.
  • the Dynamic Shear peak stress is at least 1.5 or 1.75 to ensure no displacement in the shear direction in response to applied shear stress to ensure no damage to adhered components.
  • the inclusion of (meth)acryl macromer can also increase the Stress at break of the cured composition according to the Uniaxial Tensile Test.
  • the tensile stress break is at least 3, 4, 5, 6, or 7 MPa.
  • the tensile stress at break is no greater than 10, 15, 20 MPa.
  • the tensile yield stress is in the range of 4-8 MPa.
  • the tensile strain at break is at least 25% or 50% and typically no greater than 200% or 150%.
  • the (meth)acryl macromers are typically selected so that it is not waxy at room temperature. That is, the macromer is selected to be non-crystalline and a liquid at room temperature.
  • the macromer often has a glass transition temperature (as measured using a homopolymer of the macromer) that is no greater than 0°C.
  • the macromer glass transition temperature can be no greater than -10°C -20°C -30°C, -40°C, -50°C, or -60°C.
  • Such a low glass transition temperature imparts compliance and flexibility to the (meth)acrylic copolymer and to the adhesive composition containing the (meth)acrylic copolymer.
  • a crosslinking monomer optionally be included in the polymerizable composition.
  • the crosslinking monomer typically contains a plurality of polymerizable (meth)acryloyl groups (e.g., 2, 3, or 4 (meth)acryloyl groups). That is, the crosslinking monomer is typically a multifunctional (meth)acrylate monomer.
  • Crosslinking the (meth)acrylic copolymer can contribute to the dimensional stability of the curable composition.
  • crosslinking monomers with two (meth)acryloyl groups include, but are not limited to, glycerol di(meth)acrylate, hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3 -propanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,4-cyclohexanediol di(meth)acrylate, urethane di(meth)acrylate, and polyethylene glycol di(meth)acrylates.
  • crosslinking monomers with three (meth)acryloyl groups include, but are not limited to, glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,2,4-butanetriol tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.
  • crosslinking monomers with four or more (meth)acryloyl groups include, but are not limited to, pentaerythritol tetra(meth)acrylate, sorbitol hexa(meth)acrylate.
  • the (meth)acrylic polymer may contain 0 to 5 weight percent of polymerized units of crosslinking monomer.
  • the amount can be at least 0.01, 0.05, 0.1, 0.2, 0.3, 0.5, or at least 1 wt.% of the (meth)acrylic polymer.
  • the (meth)acrylic polymer comprises no greater than 5, 4, 3, 2, or 1 wt.% of polymerized units of crosslinking monomer.
  • the curable composition typically comprises at least 20, 25, 30, 35, 40, or 45 wt.% of (meth)acrylic polymer based on the total organic components of the curable composition. In some embodiments, the curable composition comprises no greater than 60, 55, 50, 45, or 40 wt.% of (meth)acrylic polymer.
  • the (meth)acrylic polymer typically has a weight average molecular weight of at least 100,000 Daltons.
  • the weight average molecular weight can be at least 200,000 Daltons, at least 300,00 Daltons, at least 400,000 Daltons, at least 500,000 Daltons, or at least 600,000 Daltons and up to 1,000,000 Daltons, up to 2,000, 000 Daltons, or up to 3,000,000 Daltons or even higher.
  • the weight average molecular weight can be determined using size exclusion chromatography (SEC) with polystyrene standards.
  • the (meth)acrylic copolymer refers to a copolymer that is formed from a polymerizable composition having a plurality of different types of monomers.
  • the (meth)acrylic copolymer may be characterized as a random copolymer.
  • the (meth)acrylate copolymer may not be completely random because differences in concentration and reactivity of the monomers may create conditions where the early stages of polymerization may favor polymerization of one type of monomer in the polymerizable composition.
  • the (meth)acrylic polymer may be characterized as a statistical (meth)acrylic copolymer.
  • the terms “statistical” and “random” are often used interchangeably in polymeric publications.
  • the (meth)acrylic copolymer is typically not a “block” or “multi-block” polymer. However, the (e.g. random, statistical) (meth)acrylic copolymer is often utilized in combination with a (meth)acrylic multiblock copolymer.
  • the curable composition includes a (meth)acrylic multiblock copolymer (e.g., as a film forming polymer).
  • multiblock copolymer refers to a copolymer having a plurality of different polymeric segments, which are known as “blocks”. Each block can be a homopolymer (i.e., a polymeric segment formed from a single type of monomer) or a copolymer (i.e., a polymeric segment formed from multiple (i.e., two or more) different types of monomers).
  • the boundary between adjacent blocks in the block copolymer can be sharp (i.e., the composition of the monomeric units changes abruptly at the boundary between two blocks) or tapered (i.e., the composition of the monomeric units does not change abruptly at the boundary between two blocks but is mixed in a transition region near the boundary; the transition region contains monomeric units from both adjacent blocks).
  • triblock copolymer refers to a multi-block copolymer having three different polymeric blocks and the term “diblock copolymer” refers to a multi-block copolymer having two different polymeric blocks. Both the triblock copolymer and the diblock copolymer contain polymeric blocks arranged in a linear manner relative to each other. Stated differently, the diblock copolymers and triblock copolymers are not star copolymers, graft copolymers, comb copolymers, dendrimers, or other macromolecules having substantially nonlinear architectures.
  • the (meth)acrylic multiblock copolymer is a triblock copolymer.
  • the curable composition contains both a triblock copolymer and a diblock copolymer.
  • the (meth)acrylic monomers include (meth)acrylate monomers, (meth)acrylic acid monomers, (meth)acrylamide monomers, and mixtures thereof.
  • at least 80 weight percent or more of the polymerized monomeric units of the multiblock copolymer are from (meth)acrylic monomers.
  • the (meth)acrylic multiblock copolymer comprises at least 85, 90, 95, 97, 98, 99, or 100 wt.% of polymerized (meth)acrylate monomers.
  • the triblock typically has an A-B-A structure with the A and B blocks selected to have solubility parameters that are sufficiently different to cause phase separation between the A blocks and the B block.
  • the two A blocks and the B block of the (meth)acrylic triblock copolymer A-B-A are typically selected to have different glass transition temperatures.
  • the A blocks which typically have a higher glass transition temperature than the B, can be referred to as “hard” blocks while the B block can be referred to as a “soft” block.
  • the A blocks are usually selected to be more rigid than the B block.
  • the A blocks can be thermoplastic and can provide semi-structural or structural strength and/or shear strength to the adhesive composition.
  • the B block can be a viscous material and can provide tack and adhesive strength to the adhesive composition.
  • the A blocks of the (meth)acrylic triblock copolymer A-B-A are typically selected to have a glass transition temperature (T g ) equal to at least 50°C as measured using Dynamic Mechanical Analysis.
  • the glass transition temperature is at least 50°C, 60°C, 70°C, 75°C, 80°C, 90°C, 100°C.
  • the glass transition temperature is typically no greater than 200°C, 190°C, 180°C, 175°C, 170°C, 160°C, 150°C, 140°C, 130°C, 125°C, 120°C, 110°C, or 100°C.
  • the B block of the (meth)acrylic triblock copolymer A-B-A is a viscous segment and is typically selected to have a glass transition temperature no greater than 20°C as measured using Dynamic Mechanical Analysis. In some embodiments, the glass transition temperature is no greater than 10°C, 5°C, 0°C, -10°C, -20°C, or -30°C. The glass transition temperature is often at least -70°C, - 60°C, -50°C, -40°C, -30°C depending on the composition of monomers used to form the B block.
  • the (meth)acrylic triblock copolymer A-B-A has two polymeric A blocks and one polymeric B block. Each of these blocks can be a homopolymer or a copolymer (e.g., a random copolymer).
  • the (meth)acrylic triblock copolymer comprises at least 10, 20, 25, 30, 35 wt.% A block based on the total weight of the (meth)acrylic triblock copolymer. In some embodiments, the (meth)acrylic triblock copolymer comprises no greater than 55, 50, 45, 40, or 35 wt.% A block.
  • the (meth)acrylic triblock copolymer comprise 45, 50, 55, 60, 70 or 80 wt.% B block based on the total weight of the (meth)acrylic triblock copolymer. In some embodiments, the (meth)acrylic triblock copolymer comprises no greater than 90, 80, 75, 70, 65, or 60 wt.% B block. Together, the weight percent of the A blocks and the weight percent of the B block is nearly 100 weight percent based on the total weight of the (meth)acrylic triblock copolymer (i.e., there can be a small amount of initiator residue present as well).
  • the (meth)acrylic block copolymer contains 15 to 55 weight percent A blocks and 45 to 85 weight percent B block, 15 to 40 weight percent A block and 60 to 85 weight percent B block, 20 to 55 weight percent A blocks and 45 to 80 weight percent B block, 20 to 40 weight percent A block and 60 to 80 weight percent B block, or 20 to 35 weight percent A block and 65 to 80 weight percent B block.
  • Each of the two A blocks of the (meth)acrylic triblock copolymer A-B-A can be about the same molecular weight. That is, the weight ratio of the two A blocks of the (meth)acrylic triblock copolymer is often 1:1 or close to 1:1 such as greater than 0.9:1. However, other weight ratios can also be used such as in a range of 0.65: 1 to 0.99: 1. In many cases, the weight ratio of the two A blocks of the (meth)acrylic triblock copolymer is no lower than 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 0.98:1, or 0.99:l.
  • Each A block of the (meth)acrylic triblock copolymer A-B-A is usually prepared from a monomer composition that includes an alkyl methacrylate.
  • Suitable alkyl methacrylates for preparing the A blocks often have an alkyl group with 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, 1 to 5 carbon atoms, or 1 to 4 carbon atoms. If the alkyl group has 3 to 5 carbon atoms, it is typically branched. If the alkyl group has 6 to 10 carbon atoms, it is typically cyclic or bicyclic.
  • the alkyl methacrylates include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, methylcyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and isobomyl methacrylate.
  • These monomers when polymerized as a homopolymer, have a glass transition temperature equal to at least 50°C.
  • the A blocks are homopolymers and each homopolymer is a poly(alkyl methacrylate).
  • Example poly(alkyl methacrylates) include poly(methyl methacrylate), poly(ethyl methacrylate), poly(isopropyl methacrylate), poly(isobutyl methacrylate), poly(sec -butyl methacrylate), poly(tert-butyl methacrylate), poly(cyclohexyl methacrylate), poly(methylcyclohexyl methacrylate), poly(3,3,5-trimethylcyclohexyl methacrylate), and poly(isobomyl methacrylate).
  • the first monomer composition used to form the first A block can include other optional monomers provided the resulting polymeric blocks have a glass transition temperature that is equal to at least 50°C when measured using Dynamic Mechanical Analysis.
  • the first monomer composition can include other (meth)acrylic monomers such as alkoxy substituted alkyl methacrylates, aryl methacrylates, aralkyl methacrylates, aryloxy substituted alkyl methacrylate, cyclic alkyl acrylates having a cyclic group with 6 to 10 carbon atoms, bicyclic alkyl acrylates having a bicyclic alkyl group with at least 8 carbon atoms, or a mixture thereof.
  • Suitable alkoxy substituted alkyl methacrylates often have an alkyl group with 1 to 4 carbon atoms and an alkoxy group with 1 to 4 carbon atoms.
  • An example is 2-methoxyethyl methacrylate.
  • Suitable aryl methacrylates typically have an aryl group with 6 to 10 carbon atoms.
  • An example aryl methacrylate is phenyl methacrylate.
  • Suitable aralkyl methacrylates typically have aralkyl groups with 7 to 10 carbon atoms.
  • An example aralkyl methacrylate is benzyl methacrylate.
  • Suitable aryloxysubstituted alkyl methacrylates often have an aryloxy-substituted alkyl group with 7 to 10 carbon atoms.
  • An example aryloxy-substituted alkyl methacrylate is 2-phenoxyethyl methacrylate.
  • An example cyclic alkyl acrylate is cyclohexyl acrylate and an example bicyclic acrylate is isobomyl acrylate.
  • the first monomer composition used to form the A blocks can include various optional (meth)acrylic polar monomers provided the glass transition temperature of each resulting block is equal to at least 50°C. If present, these polar monomers are usually present in an amount no greater than 10, no greater than 5, no greater than 2, or no greater than 1 weight percent based on a total weight of the monomers in the respective monomer composition. Suitable polar monomers include, for example, a hydroxy group or a glycidyl group. Typically, acidic monomers and nitrogen-containing monomers are not selected (e.g., the first monomer composition is often free of such monomers).
  • Specific monomers include, but are not limited to, hydroxy alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate as 2-hydroxypropyl (meth)acrylate, as well as glycidyl (meth)acrylate. In many embodiments, however, there are no polar monomers in the A blocks.
  • the first monomer composition used to form the A blocks can include other optional monomers that are not (meth)acrylic monomers provided that greater than 80 weight percent of the monomers in the block are (meth)acrylic monomers and provided that the resulting polymeric blocks have a glass transition temperature that is equal to at least 50°C when measured using Dynamic Mechanical Analysis.
  • vinyl monomers such as styrene, styrene-type monomers (e.g., alpha-methyl styrene, 3-methyl styrene, 4-methyl styrene, ethyl styrene, isopropyl styrene, tert-butyl styrene, dimethyl styrene, 2,4,6-trimethyl styrene, and 4-methoxy styrene), and vinyl acetate.
  • styrene styrene-type monomers (e.g., alpha-methyl styrene, 3-methyl styrene, 4-methyl styrene, ethyl styrene, isopropyl styrene, tert-butyl styrene, dimethyl styrene, 2,4,6-trimethyl styrene, and 4-methoxy
  • the A blocks of the (meth)acrylic triblock copolymer are often a homopolymer formed from an alkyl methacrylate and the resulting polymeric block has a glass transition temperature equal to at least 50°C as measured using Dynamic Mechanical Analysis.
  • both A blocks are the same homopolymer, which is a poly(alkyl methacrylate).
  • the A blocks are poly(methyl methacrylate).
  • the (meth)acrylic triblock copolymer comprises at least 15, 20, 15, 35, or 40 wt.% poly(methyl methacrylate).
  • the (meth)acrylic triblock copolymer comprises no greater than 50, 45, 40, 35, 30, 25, or 20 wt.% poly(methyl methacrylate).
  • the B block of the (meth)acrylic triblock copolymer A-B-A is typically formed from monomers that will provide polymeric blocks having a glass transition temperature no greater than 20°C as measured using Dynamic Mechanical Analysis.
  • the B block is often prepared from a monomer composition that includes an alkyl acrylate.
  • the B block is a polymeric material formed from a second monomer composition that includes an alkyl acrylate.
  • Suitable alkyl acrylates for forming the B block often have an alkyl group with at least 1 or 2 carbon atoms and no greater than 20, 18, 16, 14, 12, or 10 carbon atoms.
  • the alkyl group can be linear, branched, cyclic, or a combination thereof (e.g., the alkyl can have a cyclic group plus a branched or linear group).
  • alkyl acrylate monomers that can be used to form the B block include, but are not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, s c-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylbutyl acrylate, 4- methyl-2 -pentyl acrylate, cyclohexyl acrylate, 2-methylhexyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, iso
  • the B block is a homopolymer.
  • homopolymers include, but are not limited to, poly(methyl acrylate), poly(ethyl acrylate), poly(n-propyl acrylate), poly(n-butyl acrylate), poly(isobutyl acrylate), polytwc-butvl acrylate), poly(isoamyl acrylate), poly(n-hexyl acrylate), poly(2 -methylbutyl acrylate), poly(4-methyl-2 -pentyl acrylate), poly(cyclohexyl acrylate), poly(2-methylhexyl acrylate), poly(n-octyl acrylate), poly(2 -octyl acrylate), poly(isooctyl acrylate), poly(2 -ethylhexyl acrylate), poly(isononyl acrylate), poly(n-decyl acrylate), poly(isodecyl
  • the B block is poly(n-butyl acrylate), poly(n-octyl acrylate), poly(2- octyl acrylate), poly(isooctyl acrylate), poly (2 -ethylhexyl acrylate), or poly(isononyl acrylate). In some even more specific instances, the B block is poly(n-butyl acrylate).
  • the second monomer composition used to form the B block can further include optional monomers provided the resulting polymeric blocks has a glass transition temperature that is no greater than 20°C when measured using Dynamic Mechanical Analysis.
  • the second monomer composition used to form the B block can optionally include a heteroalkyl (meth)acrylate, an aralkyl acrylate, an aryloxy substituted alkyl acrylate, or an alkyl methacrylate having an alkyl group that is linear or branched with at least 6 carbon atoms.
  • Suitable heteroalkyl acrylates include, but are not limited to 2-ethoxy ethyl (meth)acrylate, 2- methoxy ethyl acrylate, and 2-(2-ethoxyethoxy)ethyl acrylate.
  • Suitable aryalkyl acrylates include, but are not limited to, 2-biphenylhexyl acrylate and benzyl acrylate.
  • aryloxy substituted alkyl acrylate is 2-phenoxy ethyl acrylate.
  • Suitable alkyl methacrylates are n-decyl methacrylate, lauryl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, and n-hexyl methacrylate.
  • the second monomer composition used to form the B block can include various (meth)acrylic polar monomers provided the glass transition temperature of these blocks is no greater than 20°C when measured using Dynamic Mechanical Analysis.
  • these polar monomers are usually present in an amount no greater than 10, no greater than 5, no greater than 2, or no greater than 1 weight percent based on a total weight of the monomers in the respective monomer composition.
  • Suitable polar monomers include, for example, a hydroxy-substituted alkyl (meth)acrylate.
  • the polar monomer is typically not an acidic monomer or a nitrogen containing monomer (e.g., the second monomer composition is often free of such monomers).
  • Specific polar monomers include, but are not limited to, (meth)acrylic acid, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. In many embodiments, however, there are no polar monomers in the B block.
  • the B block of the (meth)acrylic triblock copolymer is often a homopolymer formed from an alkyl acrylate and the resulting polymeric block has a glass transition temperature no greater than 20°C as measured using Dynamic Mechanical Analysis.
  • the B block is a poly(alkyl acrylate).
  • the B block is poly(n-butyl acrylate), poly(n- octyl acrylate), poly(2 -octyl acrylate), poly(isooctyl acrylate), poly(2 -ethylhexyl acrylate), or poly(isononyl acrylate).
  • the B block is a copolymer of poly(2- ethylhexyl acrylate) and methyl acrylate.
  • each A block comprises monomeric units derived from methyl methacrylate and the B block comprises monomeric units derived from n-butyl (meth)acrylate such as n-butyl acrylate.
  • the (meth)acrylic triblock copolymer A-B-A typically has a weight average molecular weight (M w ) that is at least 25, 30, 35, 40, 45, or 50 kiloDaltons (kDa). In some embodiments, the (meth)acrylic triblock copolymer A-B-A has a weight average molecular weight no greater than 200, 190, 180, 175, 170, 160, 150, 140, 130, 125, 120, 115, 110, 100, 90, 80, or 75 kDa. The weight average molecular weight is typically determined using gel permeation chromatography with polystyrene standards.
  • the (meth)acrylic triblock copolymer can be synthesized using any suitable technique. Suitable techniques can include, for example, anionic polymerization, radical polymerization, group transfer polymerization, and ring-opening polymerization reactions.
  • the polymerization can be a “living” or “controlled/living” polymerization, which can advantageously produce block copolymer structures that are well defined.
  • Specific synthesis methods include atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer polymerization (RAFT) processes. Such processes are disclosed, for example, in U.S. Pat. Nos.
  • Living polymerizations can also provide block copolymers with sharp transitions between the blocks.
  • Block copolymers having A blocks and a B block can have regions near the block borders that contain a mixture of monomeric units of A and monomeric units of B.
  • the size of such regions can be minimized, or even eliminated, leading to a sharper transition from an A block to a B block.
  • This can be beneficial when phase separation is desired because a region of mixed monomeric units can be compatible with both blocks, thereby reducing the phase separation.
  • a sharp transition with minimal regions of mixed monomeric units can promote phase separation.
  • Suitable commercially available (meth)acrylic triblock copolymers can be obtained from under the trade designation “KURARITY” from Kuraray Co., Ltd. (Tokyo, Japan). These include, for example, KURARITY LA2330, LA3320, LA2140, LA2270, KL-LK9333, LK9243, KL-LH8156 and LA2250.
  • KURARITY LA2330, LA3320, LA2140, LA2270, KL-LK9333, LK9243, KL-LH8156 and LA2250 Other suitable commercially available (meth)acrylic triblock copolymers can be obtained from under the trade designation “NANOSTRENGTH” from Arkema (Colombes, France). These include, for example, NANOSTRENGTH M51, M52, M53, M55, M65, and M75.
  • curable composition contains at least 3, 4, 5 ranging up to 40 wt.% (meth)acrylic multiblock copolymer based on a total weight of resin components in the curable composition.
  • the amount can be at least 10, 12, 15, 20, 25, or at least 30 wt.%. In some embodiments, the amount is no greater than 40, 35, 30, 25, 20, 15, or 10 wt.%.
  • the curable composition can optionally include a (meth)acrylic diblock copolymer.
  • the diblock copolymer which can be referred to as a C-D diblock copolymer, typically includes a C block that can prepared from the same monomers that are described above as being suitable for forming the A blocks in the triblock copolymer.
  • the D block of the diblock copolymer can be prepared from the same monomers described above as being suitable for forming the B blocks in the triblock copolymer. If a diblock is used in combination with a triblock copolymer, the A and C blocks are often formed from the same monomer(s) while the B and D blocks are often formed from the same monomer(s).
  • the (meth)acrylic diblock copolymer often contains 5 to 30 weight percent C block and 70 to 95 weight percent D block.
  • the amount of the C block and be at least 5, 10, 15, 20 wt.% based on a total weight of the diblock copolymer. In some embodiments, the amount of C block is no greater than 30, 25, 20, or 15 wt.%.
  • the amount of the D block can be at least 70, 75, 80, 85 or 95 wt.%. In some embodiments, the amount of D block is no greater than 90, 85, or 80 wt.%.
  • the sum of the amount of the C block and D block equals (or approaches due to a small amount of initiator residue) 100 weight percent.
  • the weight average molecular weight of the (meth)acrylic diblock is often in a range of 30 to 150 kDa.
  • the weight average molecular weight is often at least 30, 40, 50, 60, 70, 80, 90, 100 kDa. In some embodiments, the weight average molecular weight is not greater than 150, 140, 130, 120, 110, 100, 90, or 80 kDa.
  • the weight average molecular weight can be determined by gel permeation chromatography using polystyrene standards.
  • the curable composition typically contains 0 to 30 wt.% of the optional (meth)acrylic diblock copolymer based on the total weight of resin components in the curable composition. If present, the amount can be at least 5, 10, 15, 20 weight percent wt.%. In some embodiments, the amount of (meth)acrylic diblock copolymer is no greater than 30, 25, 20, 15, or 10 wt.%. In many embodiments, the curable composition does not contain the optional (meth)acrylic diblock copolymer.
  • the polymerizable composition typically includes a free-radical initiator.
  • the free-radical initiator can be a thermal initiator or a photoinitiator.
  • Suitable thermal initiators include various azo compound such as those commercially available under the trade designation VAZO from Chemours Co. (Wilmington, DE, USA) including VAZO 67, which is 2, 2’-azobis(2 -methylbutane nitrile), VAZO 64, which is 2,2’-azobis(isobutyronitrile), VAZO 52, which is (2,2’-azobis(2,4-dimethylpentanenitrile), and VAZO 88, which is 1,1’- azobis(cyclohexanecarbonitrile); various peroxides such as benzoyl peroxide, cyclohexane peroxide, lauroyl peroxide, di-tert-amyl peroxide, tert-butyl peroxy benzoate, di-cumyl peroxide, and peroxides commercially available from Atofina Chemical, Inc.
  • VAZO 67 which is 2, 2’-azobis(2 -methylbutane
  • LUPERSOL e.g., LUPERSOL 101, which is 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, and LUPERSOL 130, which is 2,5-dimethyl-2,5-di-(tert-butylperoxy)-3-hexyne
  • various hydroperoxides such as tert-amyl hydroperoxide and tert-butyl hydroperoxide; and mixtures thereof.
  • a photoinitiator is used to form the (meth)acrylic copolymer. While any photoinitator can be used if the polymerization reaction to form the (meth)acrylic copolymer if the epoxy resin is not present during the polymerization reaction, it is often selected to be activated by a wavelength greater than 380 nanometers or at least 400 nanometers if an epoxy resin is present.
  • Some exemplary photoinitiators are benzoin ethers (e.g., benzoin methyl ether or benzoin isopropyl ether) or substituted benzoin ethers (e.g., anisoin methyl ether).
  • Other exemplary photoinitiators are substituted acetophenones such as 2,2-diethoxyacetophenone or 2,2-dimethoxy-2- phenylacetophenone (commercially available under the trade designation IRGACURE 651 from BASF Corp. (Florham Park, NJ, USA) or under the trade designation ESACURE KB-1 from Sartomer (Exton, PA, USA)).
  • Still other exemplary photoinitiators are substituted alpha-ketols such as 2-methyl-2- hydroxypropiophenone, aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride, and photoactive oximes such as l-phenyl-l,2-propanedione-2-(O-ethoxycarbonyl)oxime.
  • photoinitiators include, for example, 1 -hydroxy cyclohexyl phenyl ketone (commercially available under the trade designation IRGACURE 184), bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (commercially available under the trade designation IRGACURE 819), l-[4-(2 -hydroxy ethoxy )phenyl]- 2-hydroxy-2-methyl-l -propane- 1 -one (commercially available under the trade designation IRGACURE 2959), 2-benzyl-2-dimethylamino-l-(4-morpholinophenyl)butanone (commercially available under the trade designation IRGACURE 369), 2-methyl-l-[4-(methylthio)phenyl]-2-morpholinopropan-l-one (commercially available under the trade designation IRGACURE 907), and 2-hy droxy -2 -methyl- 1- phenyl propan-1 -one (commercially available under the trade designation I
  • acyl phosphine oxides such as those described, for example, in U.S. Patent 4,737,593 (Ellrich et al.).
  • the acyl phosphine oxides are often of Formula (III) or (IV).
  • each R 5 is independently a linear or branched alkyl having 1 to 18 carbon atoms, a cycloalkyl having 5 to 6 ring members (i.e., cyclopentyl and cyclohexyl), a substituted cycloalkyl, an aryl (e.g., phenyl, biphenyl, and naphthyl), a substituted aryl, or a heterocyclic ring with 5 or 6 ring members and having one or more sulfur, nitrogen, or oxygen heteroatoms.
  • Suitable substituents for substituted aryl and substituted cycloalkyl groups include halo groups (e.g., F, Cl, Br, and I), alkyl groups (e.g., alkyl groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atom), or alkoxy groups (e.g., alkoxy groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms).
  • halo groups e.g., F, Cl, Br, and I
  • alkyl groups e.g., alkyl groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atom
  • alkoxy groups e.g., alkoxy groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms.
  • Each R 6 in Formulas (III) and (IV) is independently a cycloalkyl having 5 to 6 ring members (i.e., cyclopentyl and cyclohexyl), a substituted cycloalkyl, an aryl (e.g., phenyl, biphenyl, and naphthyl), a substituted aryl, or a heterocyclic ring having one or more sulfur, nitrogen, or oxygen heteroatoms and having 5 or 6 ring members.
  • Suitable substituents for substituted aryl and substituted cycloalkyl groups include halo groups (e.g., F, Cl, Br, and I), alkyl groups (e.g., alkyl groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atom), or alkoxy groups (e.g., alkoxy groups with 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms).
  • Groups R 6 and R 7 in Formula (III) can combine to form a ring that contains 4 to 10 carbon atoms that can optionally be substituted with one or more alkyl groups (e.g., 1 to 6 alkyl groups).
  • the acyl phosphine is of Formula (III) where R 5 is aryl, R 6 is an aryl substituted with an alkyl or alkoxy, and R 7 is an aryl substituted with an alky or alkoxy.
  • the acyl phosphine is bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide, which is commercially available under the trade designation IRGACURE 819 from Ciba Specialty Chemicals.
  • the acryl phosphine is of Formula (IV) where each R 5 is any aryl and R 6 is an aryl substituted with an alkyl or alkoxy.
  • the acyl phosphine can be diphenyl(2,4,6- trimethylbenzoyl) phosphine oxide, which is commercially available under the trade designation TPO from Millipore Sigma (formerly Sigma Aldrich), St. Louis, MO, USA.
  • the acyl phosphine is of Formula (IV) where a first R 5 is an aryl, a second R 5 is an alkyl, and R 6 is an aryl substituted with an alkyl.
  • the acyl phosphine can be ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate, which is commercially available under the trade designation TPO-L from Lambson, Wetherby, West Yorkshire, England.
  • the amount of the free radical initiator can influence the molecular weight of the (meth)acrylic copolymer, with larger amounts of the free radical initiator typically producing lower molecular weight polymers.
  • the amount of the initiator is often in a range of 0.01 to 5 weight percent based on the total weight of polymerizable components in polymerizable composition.
  • the amount can be at least 0.01, at least 0.05, at least 0.1, at least 0.2, at least 0.5, or at least 1 weight percent and up to 5, up to 4, up to 3, up to 2, up to 1, or up to 0.5 weight percent.
  • Chain-transfer agents optionally can be included in the polymerizable composition to control the molecular weight of the (meth)aciylic copolymer.
  • Suitable chain-transfer agents include, but are not limited to, those selected from the group of carbon tetrabromide, hexabromoethane, bromotrichloromethane, 2-mercaptoetbanol, tert-dodecylmercaptan, isooctyltbioglycoate, 3 -mercapto- 1.2-propanediol, cumene, pentaerythritol tetrakis(3 -mercapto butyrate) (available under the trade name KARENZ MT PEI from Showa Denko), ethylene glycol bisthioglycolate, and mixtures thereof.
  • the amount of chain transfer agent is typically at least 0.05, 0.1, 0.2, 0.3, 0.5 weight percent based on the total weight of monomers in the polymerizable composition. In some embodiments, tire amount of the chain transfer agent is no greater than 5, 4.5, 4, 3.5, 3, 2.5, 2, 1.5 or 1 wt.%.
  • organic solvents include, but are not limited to, methanol, tetrahydrofuran, ethanol, isopropanol, pentane, hexane, heptane, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate, toluene, xylene, ethylene glycol alkyl ether, propylene carbonate, and mixtures thereof.
  • the organic solvent can be added to dissolve a reactant in the curable composition, can be added to lower the viscosity of the curable composition to facilitate its coating, printing or dispensing, or can be a residue from the preparation of the (meth)acrylate copolymer having pendant (meth)acryloyl groups.
  • the amount of the organic solvent in the curable composition can be in a range of 0 to 10 weight percent based on a total weight of the curable composition. In some embodiments, the amount is at least 0.5, 1, 2, 3, 4 wt.%. In some embodiments, the amount of solvent is no greater than 10, 9, 8, 7, 6, or 5 wt.%.
  • curable compositions include optional silica particles.
  • Silica is a thixotropic agent and is added to provide shear thinning. Silica has the effect of lowering the viscosity of the curable composition when force (shear) is applied. When no force (shear) is applied, however, the viscosity seems higher. That is, the shear viscosity is lower than the resting viscosity.
  • the silica particles typically have a longest average dimension that is less than 500, 400, 300, 200 nanometers, or less 100 nanometers.
  • the silica particles often have a longest average dimension that is at least 5, 10, 20, or 50 nanometers.
  • the silica particles are fumed silica.
  • the silica particles are non-aggregated nanoparticles.
  • the amount of silica particles can be 0 or at least 0.5, 1, 1.5, or 2 wt.% percent of the toal composition. In some embodiments, the amount of silica particles is no greater than 10, 8, or 5 wt.%.
  • silane compounds can be included in the curable composition.
  • the silane can be added to promote adhesion to the first substrate and/or the second substrate that are bonded together with the cured composition.
  • the silane groups have a silyl group that is particularly effective for increasing the adhesion to substrates having hydroxyl groups such as, for example, glass or ceramic surfaces.
  • the silyl groups are often of formula -Si(R 8 ) x (OR 9 )3- x where each R 8 and each R 9 is independently an alkyl. Suitable alkyl groups for R 8 and R 9 often have 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms.
  • the variable x is 0, 1, or 2.
  • the silyl group has at least one alkoxy group that can undergo hydrolysis and react with a siliceous surface.
  • the silane can be a hydrophobic or hydrophilic. That is, the silane can be of formula R 10 -Si(R 8 ) x (OR 9 )3- x where R 10 can be a hydrophobic or hydrophilic group. Any hydrophobic or hydrophilic group can be used provided it does not interfere with the cationic polymerization of the epoxy resin. That is, R 10 usually lacks a nitrogen-containing group.
  • the silane is a hydrophilic silane and group R 10 can react with one of the components of the curable composition such as with a group on the (meth)acrylate copolymer. Such a reaction can result in the covalent attachment of the silane to the cured composition.
  • silanes are glycidyl ether silanes where R 10 contains a glycidyl group.
  • examples of such silanes include, but are not limited to, (3- glyciyloxypropyl)trimethoxysilane.
  • the amount of the optional silane can be 0 or at least 0.1, 0.2, 0.3, 0.5, or 1 wt.% based on the total curable composition. In some embodiments, the amount of silane is no greater than 10, 8, 6, 5, 4, 3, 2 wt.%,
  • Still other optional components include, for example, fillers, stabilizers, plasticizers, tackifiers, flow control agents, cure rate retarders, adhesion promoters (for example, titanates), impact modifiers, expandable microspheres, glass beads or bubbles, thermally conductive particles (e.g., alumina), electrically conductive particles, glass, clay, talc, pigments, colorants, and antioxidants.
  • the optional components can be added, for example, to reduce the weight of the semi-structural or structural adhesive layer, to adjust the viscosity, to provide additional reinforcement, to modify the thermal or conductive properties, to alter the rate of curing, and the like. If any of these optional components are present, they are typically used in an amount that does not prevent the printing or dispensing of the curable composition.
  • the curable compositions are free or substantially free of fiber reinforcement.
  • substantially free means that the curable compositions contain no greater than 1, 0.5, 0.2, 0.1, 0.05, 0.01 wt. % of fibers.
  • a precursor composition is formed initially.
  • the precursor composition of the curable composition contains at least the polymerizable composition for formation of the (methjacrylic copolymer. It often additionally contains the (methjacrylic triblock copolymer dissolved in monomers of the (methjacrylic copolymer.
  • the precursor composition comprises a partially (e.g. free radically) polymerized reaction product of at least some of the monomers used to form the (methjacrylic copolymer.
  • the partially (e.g. free radically) polymerized reaction product is formed using photoinitiators that can be activated by exposure to UV radiation at wavelengths less than 380 manometers (nm) such as in a range of 300 to less than 380 nm.
  • the free radical initiators can be activated at wavelength between 300 and 370 nm, between 330 and 370 nm, between 350 and 370 nm, or near 365 nm.
  • One such photoinitiator is 2, 2-dimethoxy-2 -phenylacetophenone, obtained under the trade designation, “IRGACURE 651” from BASF (Florham Park, NJ, USA).
  • the first actinic light source is selected so that it emits over wavelengths that are not significantly absorbed by the photoacid generator.
  • the first actinic light source is selected to produce produces a spectral output with a peak intensity at a first wavelength that is at least 380 nanometers (nm), at least 383 nm, at least 386 nm, at least 390 nm, or at least 393 nm.
  • the peak intensity of the first actinic light source can be at a wavelength of up to 420 nm, up to 419 nm, up to 418 nm, up to 417 nm, or up to 416 nm.
  • the excitation dose used to activate the photoinitiator can be at least 200 mJ/cm 2 , at least 400 mJ/cm 2 , at least 600 mJ/cm 2 , at least 800 mJ/cm 2 , at least 1000 mJ/cm 2 , at least 1500 mJ/cm 2 , or at least 2000 mJ/cm 2 .
  • the excitation dose can be up to 6400 mJ/cm 2 , up to 6000 mJ/cm 2 , 5000 mJ/cm 2 , up to 4000 mJ/cm 2 , up to 3000 mJ/cm 2 , up to 2500 mJ/cm 2 , or up to 2000 mJ/cm 2 .
  • LED ultraviolet (UV) sources are advantageous because they provide UV light over a much narrower wavelength range compared with other UV light sources such as black lights and mercury lamps. LED sources are commercially available that emit radiation, for example, at 395 nm or 405 nm.
  • the precursor composition Prior to exposure to the first wavelength of actinic radiation, the precursor composition can be applied onto a first substrate (or, alternatively, a first release liner). In many embodiments, the precursor composition is coated onto a release liner prior to exposure to the first wavelength of ultraviolet radiation. Upon exposure to the first wavelength of actinic radiation, the precursor composition undergoes a free radical polymerization reaction resulting in the formation of the (meth)acrylic copolymer.
  • the curable composition is rendered dimensionally stable by the combined presence of the (meth)acrylic multiblock copolymer, which can form physical crosslinks, and the (meth)acrylic copolymer, which can be chemically crosslinked.
  • an article that contains the curable composition adhered to the first substrate or on a release liner can be prepared by a manufacturer.
  • a customer can subsequently irradiate the curable composition with a second wavelength of light and position the irradiated composition adjacent to a second substrate. That is, the final curing step is done by the customer. If the partially curable composition is on a release liner, the release liner can be removed, and the curable composition attached to a first substrate prior to exposure to the second wavelength of actinic radiation.
  • the curable composition often functions as a pressure-sensitive adhesive.
  • the curable composition is positioned between a first release liner and a second release liner.
  • the first release liner can be removed for placement of the curable composition adjacent to a first substrate while the second substrate can be removed for placement of the curable composition adjacent to a second substrate.
  • the cured composition is a polymerized reaction product of the curable composition.
  • the cured composition typically contains a film forming polymeric material such as (methjacry lie -based multiblock copolymer and/or statistical (meth)acrylic-based copolymer, and a polymerized (cured) epoxy resin.
  • the curable composition When the composition comprises a film forming polymeric material, the curable composition is typically a pressure-sensitive adhesive, it can adhere to various substrates.
  • the curable composition is positioned adjacent to a first substrate.
  • the curable composition can then be exposed to a second wavelength of actinic radiation to commence curing of the epoxy resin.
  • the curable composition After exposure to the second wavelength of actinic radiation, the curable composition is positioned adjacent to a second substrate. That is, the curable composition is positioned between the first substrate and the second substrate.
  • the curable composition can adhere both substrates together by functioning as a pressure-sensitive adhesive.
  • the first substrate Upon curing, the first substrate can be bonded to the second substrate through the cured composition.
  • the cure composition is typically a semi-structural or structural adhesive.
  • the curable composition can be readily positioned adjacent to a second substrate such that the second substrate is adhered to the first substrate by the curable composition. That is, the curable composition, which is a pressure-sensitive adhesive, can be positioned between the first substrate and the second substrate and adheres to both substrates.
  • the curable composition is exposed to a second wavelength of light to activate the photoacid generator prior to being positioned adjacent to the second substrate.
  • the term “second wavelength of actinic radiation” or similar terms can refer to a single wavelength or to a distribution of wavelengths that activate the photoacid generator.
  • the second wavelength is from a second light source that produces a spectral output with a peak intensity at a second wavelength that is different than the first wavelength.
  • the photoacid generator preferentially absorbs radiation emitted by the second actinic light source relative to radiation emitted by the first actinic light source. That is, the photoacid generator preferentially absorbs little or no radiation emitted by the first actinic light source.
  • the second wavelength is shorter than the first wavelength.
  • the second light source often has a controlled spectral output where the distribution of wavelengths is relatively narrow (or “substantially monochromatic”) and centered about a characteristic second wavelength, such as a wavelength corresponding to a peak intensity. This is not critical, however, and other distributions of wavelengths, including polymodal distributions, may be feasible.
  • the second wavelength is selected to activate the photoacid generator in the second curable composition. These compounds generate an acid when activated.
  • the second wavelength is at least 200 nm, at least 250 nm, at least 300 nm, at least 330 nm, or at least 365 nm.
  • the second wavelength can be less than 380 nm, up to 377 nm, or up to 374 nm.
  • the characteristics of second actinic light need not be as restrictive as those of the first actinic light source.
  • the second actinic light source can be based on an LED source, as described earlier.
  • the second actinic light source can be a UV black light, mercury lamp, or another broad-spectmm light source.
  • a UV black light is a relatively low light intensity source that provides generally 10 mW/cm 2 or less (as measured in accordance with procedures approved by the United States National Institute of Standards and Technology as, for example, with a UVIMAP UM 365 L-S radiometer manufactured by Electronic Instrumentation & Technology, Inc., Sterling, VA) over a wavelength range of 280 nm to 400 nm.
  • a mercury lamp is a higher intensity broad-spectrum UV source capable of providing intensities generally greater than 10 mW/cm 2 , and preferably between 15 and 6000 mW/cm 2 .
  • intensities generally greater than 10 mW/cm 2 , and preferably between 15 and 6000 mW/cm 2 .
  • an intensity of 600 mW/cm 2 and an exposure time of about 1 second may be used successfully.
  • Intensities can range from 0.1 mW/cm 2 to 6000 mW/cm 2 and preferably from 0.5 mW/cm 2 to 3000 mW/cm 2 .
  • the first and second actinic light sources can be selected to operate at different wavelengths; for example, they can have respective peak intensities at wavelengths separated by at least 10 nanometers, at least 15 nanometers, at least 20 nanometers, at least 25 nanometers, or at least 35 nanometers.
  • the first and second actinic light sources can have respective peak intensities at wavelengths separated by up to 100 nanometers, up to 80 nanometers, up to 60 nanometers, up to 50 nanometers, or up to 45 nanometers.
  • the epoxy resin When the curable composition is exposed to the second wavelength of actinic radiation, the epoxy resin is polymerized.
  • the cured composition contains reaction product of the curable composition. Additionally, exposure to the second wavelength of light can induces covalent bonding between functional groups (e.g., hydroxyl groups) of the (meth)acrylic copolymer and the epoxy resin). In this manner, the cured composition can be covalently bonded together various polymers that were in the curable composition.
  • functional groups e.g., hydroxyl groups
  • the amount of time required to form a functional semi-structural or structural bond following irradiation with the second actinic light source can be at least 1, 2, 5, 10, 20, or 30 minutes; or 1, 2, 4, 8, 12, 18 or 24 hours. In some cases, the periods of time specified above may be achieved by heating the adhesive composition.
  • the curable composition comprising film forming polymeric material typically has the properties of a pressure-sensitive adhesive. It is preferable that the pressure-sensitive adhesive has sufficient tack and dimensional stability to obviate the use of a clamp or other mechanism to secure the first substrate to the second substrate for the entirety of the second curing reaction. Often, a clamp or other mechanism is used in the early stages of curing the second curable composition to ensure that it adequately wets the surface to which it is adhered.
  • a first article includes the curable composition and at least one substrate or release liner.
  • the second article includes a cured composition positioned between two substrates such that a first substrate is bonded to a second substrate.
  • the first article includes the curable composition and either a first substrate or a first release liner positioned adjacent to the first substrate or to the first release liner.
  • the curable composition is the same as described above.
  • Some first articles include the curable composition and a first substrate positioned adjacent to the curable composition.
  • a release liner can be on a surface of the curable composition opposite the first substrate.
  • Other first articles include the curable composition and a first release liner positioned adjacent to the curable composition.
  • a second release liner can be on a surface of the curable composition opposite the first release liner.
  • the first article can be in the form of a roll. In some rolls, there are two release liners on opposite surfaces of the curable composition. In other rolls, there is a single release liner.
  • the articles with either one or two release liners can be transfer adhesive tapes. There articles are often die-cut parts having a shape and size consistent with the intended use of the curable composition.
  • the article containing the curable composition can be stored adjacent to at least one release liner for any desired amount of time such as, for example, up to 1 week, up to 2 weeks, up to 1 month, up to 2 months, up to 4 months, up to 6 months, up to 8 months, up to 10 months, or up to 1 year.
  • the curable composition in the first article is a pressure-sensitive adhesive.
  • the first article is an adhesive transfer tape.
  • the first article does not need to be reinforced with fibers as described, for example, in U.S. Patent Application Publication 2002/0182955 (Weglewski et al.).
  • a second article includes a first substrate, a second substrate, and a cured composition positioned between the first substrate and the second substrate.
  • the cured composition which is the same as described above, bonds the first substrate to the second substrate.
  • the curable composition of the first article can have a with excellent ooze resistance yet can be used to form a second article that contains a cured composition that can function as a semi-structural adhesive with good impact resistance.
  • the cured composition in the second article can be de-bonded, if desired, to the cured compositions can be removed (e.g., de-bonded) from the various surfaces of the second article after the useful lifetime of the article, to correct misplacement of a part during manufacturing, or to repair the article such as an electronic device.
  • first substrate and second substrate can be used.
  • at least one of the first substrate and the second substrate contains a metal and/or is electrically conductive.
  • Either substrate can be flexible or inflexible.
  • the substrates can be formed from a polymeric material, glass, ceramic material, metal (including various alloys), or combination thereof.
  • the first and/or second substrates are glass, ceramic materials, or metals.
  • Suitable polymeric materials can be selected from a polymeric film or a plastic composite (e.g., glass or fiber filled plastics).
  • the polymeric material can be prepared, for example, from polyolefins (e.g., polyethylene, polypropylene, or copolymers thereof), polyurethanes, polyvinyl acetates, polyvinyl chlorides, polyesters (polyethylene terephthalate or polyethylene naphthalate), polycarbonates, polymethyl(meth)acrylates (PMMA), ethylene-vinyl acetate copolymers, and cellulosic materials (e.g., cellulose acetate, cellulose triacetate, and ethyl cellulose).
  • a non-conductive substate can be coated with a conductive layer, if desired.
  • Release liners can be used in the manufacture of the articles and function as temporary substrates. That is, the release liners are replaced with permanent substrates. Suitable release liners typically have low affinity for the curable composition. Exemplary release liners can be prepared from paper (e.g., Kraft paper) or other types of polymeric material. Some release liners are coated with an outer layer of a release agent such as a silicone-containing material or a fluorocarbon-containing material (e.g., polyfluoropolyether or polyfluoroethylene).
  • the first substrate and the second substrate can be different components of an electronic device, a motorized vehicle, or a home appliance.
  • one of the substrates can be a polymeric display frame and the second substrate can be a polymeric or metallic housing within a phone, tablet, or other electronic device.
  • the two substrates can be different components of a motorized vehicle, such as an automobile, truck, airplane, or the like, or different components of a home appliance, such as a refrigerator, dishwasher, oven, washing machine, or dryer.
  • one of the substrates can be glass (such as in a windshield or electronic display or shelf) and the second substrate can be a polymeric or metallic frame or bracket.
  • the second article can be separated into its component parts by application of a direct current electric potential.
  • the first and second substrates can be separated from each other.
  • the cured composition can be cleanly removed from the substrates. This removal allows for reusing the substrates. This is particularly advantageous when the curable composition is attached to a first or second substrate that is or that contains an electronic component that can be reused or recycled.
  • An article can be a finished product or a part for incorporation into, or attachment to, another object.
  • the article is typically made up of at least two components that may be adhesively bonded together, and the article may comprise two major surfaces that are nominally parallel to each other and a thickness in a direction orthogonal to the major surfaces (e.g., sheet or multilayer film) or be three-dimensional in shape (i.e. the major surface are not parallel and the thickness may vary).
  • the shape and form of the components making up the article are also not particularly limiting.
  • a component can be a single element or a combination of elements, and the component may comprise two major surfaces that are nominally parallel to each other and a thickness in a direction orthogonal to the major surfaces (e.g., sheet or multilayer film) or be three-dimensional.
  • two or more components are interconnected, or even two different sections of the same material (e.g., one end of a composite strip of material can be folded over to adhere to the opposite end of the strip).
  • a direct current (DC) electric potential is applied across the adhesive composition prior to separation of the components.
  • the electric potential may be applied across two electrically conductive components on opposite sides of the adhesive composition, such that the surface of one component serves as a negative electrode (or negative adhesive interface) and the surface of the other component serves as the positive electrode (or positive adhesive interface).
  • the electric potential may be applied across one electrically conductive component and an electrically conductive adhesive carrier of a two-sided tape, where the surface of the conductive component or the conductive adhesive carrier serves as the negative adhesive interface and the other of the surface of the conductive component or conductive adhesive carrier serves as the positive adhesive interface.
  • Application of a DC current typically weakens the adhesive bond at the negative electrodeadhesive interface, thus reducing the amount of force required to separate components in the article. The location of debonding can be reversed by simply changing the polarity of the electric potential.
  • FIG. 1 illustrates one embodiment of an article of the present disclosure comprising two (e.g. electrically conducting) components joined together by the adhesive composition.
  • article 10 comprises a first component 12 having a first electrically conductive surface 14 and a second component 22 having a second electrically conductive surface 24.
  • the first and second components 12, 22 are each made from electrically conductive material(s). The nature of the conductive materials is not particularly limiting.
  • the first electrically conductive surface 14 and second electrically conductive surface 24 are each selected from the group consisting of a metal, a mixed metal, an alloy, a metal oxide, a composite metal, a conductive plastic, a conductive polymer, or combinations thereof.
  • the composition of the first electrically conductive surface 14 is different from the composition of the second electrically conductive surface 24.
  • the compositions of the first and second electrically conductive surfaces 14, 24 are the same.
  • the adhesive composition 30 joins the first and second components 12 and 22 together at the first conductive surface 14 and the second conductive surface 24.
  • the adhesive composition exhibits on-demand debonding behavior by application of a DC electric potential across the adhesive composition 30.
  • the first conductive surface 14 serves as the positive adhesive interface
  • the second conductive surface 24 serves as the negative adhesive interface.
  • Application of a DC electric potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e. the second conductive surface 24), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 22 from the first component 12.
  • little-to-no adhesive residue remains on the second conductive surface 24 after separation.
  • the adhesive composition in some embodiments, less than 10%, less than 5%, or less than 1% of the adhesive composition (by weight) remains on the second component 22 after separation. In some preferred embodiments, no adhesive composition remains on the second component 22 after separation. In some embodiments, it is possible to reuse the adhesive composition allowing the first component 12 to be rejoined to the second component 22 or adhered to a completely different component or article. If it is desirable that the adhesive remain on the second component 22 after separation, the polarity of the DC electric potential can be reversed so that the first conducting surface 14 serves as the negative adhesive interface.
  • Electrically conductive components include those components made entirely from electrically conducting material(s), as illustrated in FIG. 1 A, as well as those components made from nonconducting material(s) coated with electrically conductive material(s), as illustrated in FIG. IB.
  • the first component 12 comprises a first nonconductive material 16 and a first electrically conductive coating 18 to provide the first electrically conductive surface 14.
  • the second component 22 comprises a second nonconductive material 26 and a second electrically conductive coating 28 to provide the second electrically conductive surface 24.
  • one of the components could be made entirely of electrically conducting material(s) and the other component could be made of nonconducting material(s) coated with electrically conductive material(s).
  • the conductive coating may only partially coat the component, as illustrated in FIG. IB, or completely coat the outside surface of the component.
  • the coating is a solid layer.
  • the coating is pattern coated onto the surface of the component.
  • the electrically conductive material is not particularly limiting and can include materials selected from the group consisting of a metal, a mixed metal, an alloy, a metal oxide, a composite metal, a conductive plastic, a conductive polymer, or combinations thereof.
  • the adhesive composition 30 in FIG. IB joins the first and second components 12 and 22 together.
  • the first conductive surface 14 serves as the positive adhesive interface and the second conductive surface 24 serves as the negative adhesive interface.
  • Application of a DC electric potential 40 across the adhesive composition 30 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., second electrically conductive surface 24), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 22 from the first component 12. If it is desirable that the adhesive composition remain predominately on the second component, the polarity of the DC electric potential can be reversed so that the first electrically conducting surface serves as the negative adhesive interface.
  • the articles in FIG. 1 A-B can be further adapted to join and subsequently de-bond (i.e., separate) nonconductive objects or elements using the adhesive composition, as illustrated in FIG. 1C.
  • the article in FIG. 1C includes a conductive first component 12 having a first electrically conductive surface 14, and a conductive second component 22 having a second electrically conductive surface 24.
  • the first and second components 12 and 22 are joined together by the adhesive composition 30.
  • the first and second components can be made of electrically conductive material(s), it should also be understood that the first and/or second components can be made from nonconductive material(s) and coated with electrically conductive material(s), such as illustrated in FIG. IB.
  • FIG. 1C differs from FIGS.
  • first outer adhesive 50 is added to a second side 19 of the first component 12 opposite the adhesive composition 30, and a second outer adhesive 60 is added to a first side 29 of the second component 22 opposite the adhesive composition 30.
  • the outer adhesives 50 and 60 can be the same or different and are not particularly limiting, as long as the outer adhesives 50 and 60 bond to the nonconductive object or element and function for the intended application.
  • the outer adhesive is a pressure sensitive adhesive.
  • the outer adhesive is the curable composition described herein.
  • An optional release liner may be applied to the first outer adhesive 50, the second outer adhesive 60, or both to protect the outer adhesives during transport and storage of the article.
  • a release liner is applied to each of the first and second outer adhesives. In other embodiments, a release liner is applied to one of the outer adhesives and the article is wound up on itself so that the other outer adhesive is in direct contact with the release agent of the release liner for the purpose of storage and transport. The adhesive composition can then be unrolled when ready for use.
  • Release liners can be made, for example, of kraft papers, polyethylene, polypropylene, polyester, or composites of any of these materials. The liners are preferably coated with release agents such as fluorochemicals or silicones. In some preferred embodiments, the liners are papers, polyolefin films, or polyester films coated with silicone release materials.
  • release liners examples include POLYSLIK silicone release papers available from Loparex (Cary, NC), Silicone 1750 coated films from Infiana (Forchheim, Germany), siliconized polyethylene terephthalate films available from H.P. Smith Co. (Stoneham, MA), and 3M SCOTCHPAK 9741 Release liner from 3M Company (St. Paul, MN).
  • the first and second components comprise two major surfaces that are nominally parallel to each other and a thickness in a direction orthogonal to the major surfaces (e.g., sheet or multilayer film).
  • the major surfaces e.g., sheet or multilayer film.
  • the optional release liners is removed from the first outer adhesive 50 and the first outer adhesive adhered to a nonconductive object.
  • the second optional release liner is removed from the second outer adhesive 60 and the second outer adhesive 60 adhered to a different nonconductive object, such that the nonconductive objects are adhesively joined.
  • the nonconductive objects can be separated on-demand by application of an electric potential across the adhesive composition, as illustrated in FIGS. 1 A-B. In this instance, separation will result in one nonconductive object having the first component adhesively bonded thereto and the other nonconductive object with the second component adhesively bonded thereto.
  • Figure 2 illustrates another embodiment of an article 110 of the present application where the adhesive composition is a two-sided tape that joins the first and second components together.
  • the article 110 comprises a first component 112 having a first electrically conductive surface 114 and a second component 122 having a second electrically conductive surface 124.
  • the first and second components can be made of conductive material(s), as illustrated in FIG. 2 A, or one or both first and second components can be made of nonconductive material(s) and at least partially coated with electrically conductive material(s), as described above with respect to FIG. 1.
  • the adhesive composition 130 is disposed between the first electrically conductive surface 114 and the second electrically conductive surface 124 and joins the first component 112 to the second component 122.
  • the adhesive composition 130 is a two-sided adhesive further comprising a carrier 170 having a first major surface 172 and a second major surface 174 opposite the first major surface.
  • a first adhesive composition 132 is on the first major surface 172 of the carrier 170.
  • a second adhesive composition 134 is on the second major surface 174 of the carrier 170.
  • the composition of the first adhesive composition is the same as the second adhesive composition.
  • the composition of the first adhesive composition is different than the second adhesive composition.
  • a surface 136 of the first adhesive composition 132 opposite the carrier 170 is in contact with the first conductive surface 114 of the first component 112.
  • a surface 138 of the second adhesive composition 134 opposite the carrier 170 is in contact with the second conductive surface 124 of the second component 122.
  • the carrier is a porous material that allows for physical contact between the first and second adhesive compositions.
  • exemplary carriers include paper, woven or nonwoven fabrics, a porous film, a metal mesh, a metal grid, or combinations thereof.
  • the carrier is electrically conductive.
  • Such conductive carriers may be porous or nonporous and include a metal mesh, a metal grid, a metal foil, a metal plate, a conductive polymer, a conductive foam, a conductive tissue, or combinations thereof.
  • the first electrically conductive surface 114 serves as the positive adhesive interface and the second electrically conductive surface 124 serves as the negative adhesive interface.
  • the carrier is made from a porous material
  • application of a DC electric potential 140 across the adhesive composition 130 results in a weakening of the adhesive bond at the negative adhesive interface (i.e., second electrically conductive surface 124), as measured, for example, according to the work of adhesion per surface area, thus making it easier to separate the second component 122 from the first component 112.
  • the polarity of the DC electric potential can be reversed so that the first electrically conducting surface serves as the negative adhesive interface.
  • the carrier in FIG. 2A is a nonporous conductive material
  • application of a DC electric potential 140 across the adhesive composition 130 can result in a weakening of the adhesive bond at the negative adhesive interface (i.e., second electrically conductive surface 124) and the first major surface 172 of the carrier 170.
  • the carrier 170 is a conductive material that serves as either the positive or the negative adhesive interface during the debonding process.
  • the first conductive surface 114 of the first component 112 is the positive adhesive interface and the first major surface 172 of the carrier 170 is the negative adhesive interface.
  • Application of a DC electric potential 140 across the first adhesive composition 132 will result in separation of the first and second components 112, 122 at the first major surface 172 of the carrier 170.
  • the first component 112 can be removed from the first adhesive composition 132 by reversing the polarity of the DC electric potential.
  • the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be the negative adhesive interface and the other of the conductive surface 124 of the second component 122 or the second major surface 174 of the carrier 170 can be the positive adhesive interface.
  • the carrier 170 serves as the negative or positive adhesive interface and the first conductive surface 114 of the first component 112 serves as the other of the negative or positive adhesive interface
  • only the first adhesive composition 132 across which the DC electric potential is applied need comprise a cured composition that includes the ionic liquid.
  • the second adhesive composition 134 can in fact be any type of adhesive.
  • the carrier 170 serves as the negative or positive adhesive interface and the second conductive surface 124 of the second component 122 serves as the other of the negative or positive adhesive interface
  • only the second adhesive composition 134 across which the DC electric potential is applied need comprise a cured composition that includes the ionic liquid.
  • the first adhesive composition 132 can be any type of adhesive.
  • a two-sided tape may be used to make the article which comprises a carrier having adhesive on both sides, where only one of the adhesives comprises a cured composition that includes the ionic liquid.
  • This construction would be similar to that illustrated in FIG. 1C, where the second component 22 is a carrier.
  • a two-sided tape with a conductive carrier allows the user to strategically tailor the location of debonding within an article. This can be particularly advantageous when it is necessary to remove adhesive from a component prior to recycling and/or leave the adhesive on a component for repositioning or adherence to the same or different article.
  • the components need not be conductive to separate the first component from the second component.
  • the carrier can serve as one of the electrodes, thus increasing the types of materials that can be included in the article (i.e., adhering two conductive components or adhering a conductive component to a nonconductive component).
  • the various layers of the first adhesive article such as the electrically conductive layer(s) may comprise a surface treatment for improving adhesion.
  • Surface treatments include for example exposure to ozone, exposure to flame, exposure to a high-voltage electric shock, treatment with ionizing radiation, and other chemical or physical oxidation treatments.
  • Chemical surface treatments include primers. Examples of suitable primers include chlorinated polyolefins, polyamides, and modified polymers disclosed in U.S. Pat. Nos. 5,677,376, 5,623,010 and those disclosed in WO 98/15601 and WO 99/03907, and other modified acrylic polymers.
  • the primer is an organic solvent-based primer comprising acrylate polymer, chlorinated polyolefin, and epoxy resin as available from 3M Company as “3MTM Primer 94”. Mechanical abrading or other forms of treatment used to increase surface area can also be used for improving adhesion.
  • the articles may optionally further comprise other optional layers.
  • the surface treatments and other optional layers are selected to not detract from the debonding properties.
  • glass transition temperature which can be abbreviated “T g ” refers to the temperature at which a polymeric material transitions between being in a glassy state to being in a molten or rubbery state. The test is often performed using a rheometer as described in the Example section.
  • the term “semi-structural adhesive” refers to those cured compositions that have an overlap shear strength of at least 0.60 or at least 0.75 megaPascals (MPa). More preferably, the overlap shear strength is at least 1.0 or at least 1.5 MPa. Those cured compositions having a particularly high overlap shear strength, however, are referred to herein as “structural adhesives”. Structural adhesives are those cured compositions that have an overlap shear strength of at least 3.5, at least, at least 4, at least 5, at least 6, or at least 7 MPa.
  • a dry IL round bottom flask was charged with a PTFE magnetic stir bar, 214 g (1.25 mol) of e- decalactone (distilled from CaH 2 before use), 19 mL (19.76 g, 0.137 mol) of 4-hydroxy butyl acrylate, and 2.7 g (0.01079 mol) of diphenyl phosphate.
  • the reaction was stirred at room temperature for 9 days.
  • the conversion of e-decalactone into poly(e-decalactone) acrylate was found to be 69%.
  • the theoretical, i.e. targeted molecular weight, n 1087 g/mol.
  • the poly(e-decalactone) acrylate macromer was dissolved in 500 mL of dichloromethane and washed with 0.2 N NaOH (4 times). The organic layer was dried over magnesium sulfate, the magnesium sulfate was filtered, and the solvent was removed under reduced pressure to isolate the poly(e-decalactone) acrylate macromer.
  • PLA-MA macromer having a methacryloyl-polymerizable group was synthesized using a modified procedure reported by Ishimoto et al (Biomacromolecules 2012, 13, 3757-3768).
  • DL-Lactide (100 g) was dried under vacuum in a three necked flask.
  • hydroxy ethyl methacrylate (33 g) and Sn(Oct)2 (0.5 g) were added, and the mixture was stirred and heated at 110 °C using an oil bath for 18 hr. No further purification was done.
  • the theoretical M n 562 g/mol of PL A- MA.
  • the observed M n by H-NMR was 466 g/mol by integrating the lactide peaks with respect to the vinyl groups of the HEMA monomer.
  • the tight liner was removed (RF22N) from the adhesive bonded to the first substrate, the adhered tape was exposed to 4 J of UV-LED irradiation at 365 nm and immediately afterwards the end of the second substrate was applied to the adhesive area ensuring an overlap area of 25.4 mm x 12.7 mm.
  • the total UV energy was determined using a POWERPUCK II radiometer (available from EIT Incorporated, Sterling, Virginia, USA).
  • the bonded laminate was then compressed with a 8 Kg weight applied over the 25.4 mm x 12.7 mm adhesive bonded area at room temperature for 30 s.
  • the bonded test specimens were allowed to dwell at room temperature for 5 days prior to testing.
  • the adhesive joint was tested by gripping the opposite ends of the stainless- steel substrates within a load frame (MTS, Eden Prairie, Minnesota, USA) and tested at a rate of displacement of 10 mm/min (vertical crosshead speed). The maximum peak in the stress of the stressstrain curve was used to determine the peak stress of the adhesive specimen in MPa for Table 3.
  • the tensile pushout set up is shown in Figure 1.
  • the easy liner of the die cut was removed, and the die cut was adhered symmetrically around the center hole of the SS coupon.
  • the tight liner was then removed, and the adhesive was exposed to 4 J of UV-LED irradiation at 365 nm.
  • the total UV energy was determined using a POWERPUCK II radiometer (available from EIT Incorporated, Sterling, Virginia, USA).
  • the SS puck was then centered above the adhesive die cut and adhered to the exposed adhesive surface with hand pressure.
  • the assembly was then compressed with a 8 kg weight for 30 seconds at 23 °C and dwelled at 23 °C / 50% RH for 5 days before testing.
  • a BK Precision 1685 B power source (Yorba Linda, California, USA) was connected to the coupon and puck via a positive and negative electrode. For 120 seconds, a voltage of 50 V was applied across the coupon and puck.
  • Test specimens for uniaxial tensile testing were prepared by B stage cure activating the 8 mil thick tapes with 4J @ 365 nm of UV-LED irradiation between liners, then removing the liners and laminating them to a total thickness of 16 mil. Samples were allowed to fully cure for 5 days in a CTH (controlled temperature and humidity) room. Test specimens were cut out with a die to be 0.5” in width by 6” in length. 1” of each end of the cured tape was placed within the top and bottom grips of an MTS load frame ensuring 4” of length in-between the grips and no slack in the sample. The uniaxial tensile test was performed by pulling the cured tape specimens with a load frame (MTS) and tested at a rate of displacement of 500%/min (vertical crosshead speed).
  • MTS load frame
  • Examples E1-E2 and E13-E16 were prepared as follows: 30 wt.% LA2330 was dissolved in 70 wt.% of 2 -MBA monomer at room temperature. The other materials described in Table 2 were then added and mixed to achieve the described final wt.%. Unless otherwise stated, each of the compositions also contained 0.11 wt% of IRG 819, 0.80 wt.% of Ar 3 S PF 6 and 0.08 wt.% HDDMA.
  • compositions were coated between two release liners (RF22N and RF12N from SKC Haas, Seoul, Korea, 2 mil) at an adhesive thickness of 8 mils (200 pm) and cured under 405 nm UV-LED lights with a total dosage of 3.1 J/cm 2 as measured with a POWER PUCK II radiometer equipped with a high power sensing head (available from EIT Incorporated, Sterling, VA).
  • Examples E3 through E30 were made in the same manner as above using the materials described in Table 2. However for E3 through E12, 10 wt.% LA2330 was dissolved in 90 wt.% of 2-MBA monomer at room temperature (before adding the other materials listed in Table 2).
  • Example E17-E29 10 wt.% of acrylic block copolymer (e.g. LA2330, LA2250 etc.) was dissolved in a mixture of 45 wt.% of nBA monomer and 45 wt.% 2-EHA monomer at room temperature.
  • Example E18 contained 0.15 wt% of HDDMA instead of 0.08 wt %.
  • Examples 19 through 30 contained 0.05 wt% HDDMA instead of 0.08 wt %.
  • Example E19 also contained 0.15 wt.% of GPTS silane adhesion promoter.
  • Example E20 also contained 0.44 wt.% of KBM-503 silane adhesion promoter.
  • Example 30 was made by first dissolving the acrylic block copolymer into the D202 IP epoxide and P425 polyol mixture at 65 °C over 2 hours, then adding the XT100, BMI PF6 and 1.9 wt. % Ar 3 S PF 6 as listed as wt.% of final combined composition in Table 2, and then mixing them for 5 minutes in a speed mixer (DAC150.1 FVZ-K SPEEDMIXER (FlackTek, Inc.) at 1200 rpm.
  • DAC150.1 FVZ-K SPEEDMIXER FlackTek, Inc.
  • Example 31 was made by first dissolving the acrylic block copolymer into the D202 IP epoxide and P425 polyol mixture at 65 °C over 2 hours, then adding the XT100, and 2.2 wt. % Ar 3 S PF 6 as listed as wt.% of final combined composition in Table 2, and then mixing them for 5 minutes in a speed mixer (DAC150.1 FVZ-K SPEEDMIXER (FlackTek, Inc.) at 1200 rpm.
  • DAC150.1 FVZ-K SPEEDMIXER FlackTek, Inc.
  • curable mixtures for examples 30 and 31 bonded assemblies were prepared as described for tape samples, except liquid adhesive was applied to the first substrate, exposed to 8 J/cm2 from a 365 nm UV- LED (Omnicure 7300, Excelitas Inc, Waltham, MA) to initiate curing, and glass microspheres (SLGMS- 2.5 140-150um from Cospheric LLC, Somis, CA) were used as spacer beads for the bond line.
  • UV- LED Omnicure 7300, Excelitas Inc, Waltham, MA
  • SGMS- 2.5 140-150um from Cospheric LLC, Somis, CA glass microspheres
  • Example 32 was prepared by first dissolving B20H at 20 wt.% into nBA (70 wt.%) and HEA (10 wt.%). Then the other materials shown in Table 2B were added. E32 also contained 0.1 wt.% HDDMA, 0.1 wt.% IRG 819, and 2.2 wt.% Ar 3 S PF 6
  • Example 33 and 34 was prepared by first dissolving LA2270 at 20 wt.% into EHA (50 wt.%) and nBA (30 wt.%). Then, the other materials shown in Table 2B were added. E33 and 34 also contained 0.1 wt.% HDDMA, 0.1 wt.% IRG 819, and 1.9 wt.% Ar 3 S PF 6
  • Example 35 was prepared by first dissolving M75ST at 20 wt.% into EHA (50 wt.%) and nBA (30 wt.%). Then, the other materials shown in Table 2 A were added. E33 and 34 also contained 0.1 wt.% HDDMA, 0.1 wt.% IRG 819, and 2.1 wt.% Ar 3 S PFs
  • XT-100 and MX0150 comprise 40 wt.% rubber particles and 60 wt.% epoxy resin.
  • 37.6 wt.% MX-150 is 15 wt.% rubber particles and 20.8 wt.% epoxy resin.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Epoxy Resins (AREA)

Abstract

L'invention concerne une composition durcissable comprenant une résine époxy, au moins 1 % en poids d'un agent de renforcement qui n'est pas un polyol ; un matériau polymère filmogène ; un générateur de photoacide ; et un liquide ionique qui présente un point de fusion inférieur à 100 °C et qui présente un anion choisi parmi SbF6-, PF6- ou leur mélange. Des articles comprenant de telles compositions durcies peuvent être enlevés (par exemple, décollés) par application d'un potentiel électrique à courant continu à travers la composition durcie.
PCT/IB2025/053523 2024-04-10 2025-04-03 Adhésifs comprenant un époxy et polymère (méth)acrylique comprenant un agent de renforcement Pending WO2025215476A1 (fr)

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