CN1806025A - Silicone-based pressure-sensitive adhesive and adhesive tape - Google Patents

Abstract

Silicone-based pressure-sensitive adhesives comprising (A) (a) a gum-like organopolysiloxane having an average of at least one alkenyl group per molecule and (b) consisting essentially of R ¹ ₃ SiO _1/2 units Partial condensation products of organopolysiloxane resins composed of SiO _4/2 units or mixtures thereof; (B) organopolysiloxanes having an average of at least two silicon-bonded hydrogen atoms per molecule; (C ) an aromatic amine compound and/or an aromatic amino group-containing organopolysiloxane; and (D) a platinum catalyst. The pressure-sensitive adhesive forms a pressure-sensitive adhesive layer that can be easily peeled off after exposure to high temperature.

Description

Silicone-based pressure sensitive adhesives and adhesive tapes

technical field

[0001] The present invention relates to silicone-based pressure-sensitive adhesives and adhesive tapes, and more particularly, the present invention relates to silicone-based pressure-sensitive adhesives for forming pressure-sensitive adhesive layers, the The pressure sensitive adhesive layer is repeelable after exposure to high temperature. The present invention also relates to adhesive tapes that are releasable after exposure to elevated temperatures.

Background technique

[0002] Silicone-based pressure-sensitive adhesives possess excellent electrical insulation, heat resistance, and adhesive properties, and are used in applications requiring reliability. Depending on the curing mechanism, silicone-based pressure-sensitive adhesives can be classified into addition reaction curing types, condensation reaction curing types, and peroxide curing types. Addition reaction curing types are most preferred because they can be cured at room temperature or when accelerated curing is required, by concomitant heating.

[0003] Japanese Patent Publication No.Sho 54-37907 (corresponding to U.S. Patent No. 3983298 (September 28, 1976)) discloses a silicone-based pressure-sensitive adhesive curable by addition reaction, which Comprising (a) organopolysiloxane resins containing R ₃ SiO _1/2 units and SiO _4/2 units, wherein R is a monovalent hydrocarbon group having 6 or less carbon atoms; (b) having bonds at both ends of the molecule Vinyl diorganopolysiloxane bonded to silicon atoms; (c) an organopolysiloxane having silicon-bonded hydrogen atoms in an amount such that the silicon-bonded The amount of hydrogen atoms is 1.0-20.0 mol/mol of all alkenyl groups in components (a) and (b); and (d) platinum catalyst.

[0004] Another example of a silicone-based pressure-sensitive adhesive is shown in Japanese Patent Application No. Sho 63-22886 (corresponding to US Patent No. 4,774,297 (September 27, 1988)). It consists of the following: (A) diorganopolysiloxane having alkenyl groups bonded to silicon atoms at both ends of the molecule; (B) containing R ₃ SiO _1/2 units (wherein R is an alkyl group) , alkenyl or hydroxyl) and an organopolysiloxane resin of SiO _4/2 units; (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule in an amount such that in the composition Silicon-bonded hydrogen atoms in component (C) are 1.0 to 20.0 mol/mol alkenyl groups in component (A); (D) platinum catalyst; and (E) organic solvent.

[0005] Recently, Japanese Patent Publication No. Hei 5-34391 (corresponding to U.S. Patent No. 5,216,069 (June 1, 1993)) discloses another example of a silicone-based pressure-sensitive adhesive composed of Examples: (i) an organopolysiloxane which is a diorganopolysiloxane containing alkenyl groups having hydroxyl groups bonded to silicon atoms at both ends of the molecule and a unit containing R ₃ SiO _1/2 (where R is a monovalent hydrocarbon radical having 3 or fewer carbon atoms) and SiO _4/2 units of the partial condensation product of an organopolysiloxane; (ii) an organopolysiloxane having silicon-bonded hydrogen atoms , used in an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (ii) to alkenyl groups contained in (i) is 1-30, and (iii) a platinum catalyst.

[0006] However, known silicone-based pressure sensitive adhesives have some disadvantages. In particular, when an adhesive tape is adhered to the surface of an object having such an adhesive and is exposed to high temperature for a long time, peeling of the tape from the surface of the object to which the adhesive is attached leaves Adhesive residue. For example, when heat-treating masking tape is used during the solder reflow step during the processing of printed circuit boards (PCBs), peeling of the tape from the PCB after the operation is complete can leave a pressure-sensitive adhesive layer on the surface of the PCB. some residue material. This residue material is a source of problems in subsequent operations.

[0007] Accordingly, it is an object of the present invention to provide a silicone-based pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer that is releasable after exposure to high temperature. Another object of the present invention is to provide adhesive tapes that are releasable after exposure to high temperatures.

[0008] The silicone-based pressure sensitive adhesive of the present invention is effective in that it can form a pressure sensitive adhesive layer that can be repeatedly peeled after exposure to elevated temperatures. Similarly, an adhesive tape is effective in that it can be peeled off repeatedly after exposure to high temperatures.

Summary of the invention

[0009] The silicone-based pressure sensitive adhesives of the present invention include:

(A) a partial condensation product or mixture of ingredients (a) and (b), wherein ingredient (a) is a gum-like organopolysiloxane having an average of at least one alkenyl group per molecule, and ingredient (b) It is an organopolysiloxane resin mainly composed of R ¹ ₃ SiO _1/2 units (where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group) and SiO _4/2 units, where R ¹ ₃ SiO _1/2 units are combined with SiO The molar ratio of the _4/2 unit is 0.5-1.5;

(B) An organopolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, wherein the silicon-bonded hydrogen atoms are present in an amount of 0.5 to 150.0 mol/mol of the alkenyl group in component (A) The dosage exists;

(C) an aromatic amine compound and/or an organopolysiloxane containing an aromatic amino group in an amount of 0.001-10 parts by weight/100 parts by weight of component (A); and

(D) A platinum catalyst in an amount sufficient to provide cure of the adhesive.

[0010] The adhesive tape of the present invention includes a support film and a pressure-sensitive adhesive layer, wherein the adhesive layer is formed by curing the above-described silicone-based pressure-sensitive adhesive.

Detailed description of the invention

[0011] Ingredient (a) is an organopolysiloxane containing an average of at least one alkenyl group per molecule. If the average content of alkenyl groups per molecule is less than 1, the resulting pressure-sensitive adhesive has reduced cohesion or retention. Ingredient (a) is in the form of raw gum, and its plasticity value is preferably 50-200, even more preferably 80-180. The plasticity value is measured by applying a force of 1 kg to a spherical sample material weighing 4.2 g at 25° C. for 3 minutes according to Japanese Industrial Standard (JIS) K6249. Although there is no particular limitation on the molecular structure of component (a), a linear structure is preferred, but it may be partially branched.

[0012] The alkenyl group in component (a) may be vinyl, allyl, butenyl or pentenyl, however vinyl is preferred. Ingredient (a) may contain groups other than alkenyl groups bonded to silicon atoms. These other groups may be substituted or unsubstituted monovalent hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl and similar linear alkyl groups; isopropyl, sec-butyl , tert-butyl, isopentyl, tert-pentyl, neopentyl, tert-octyl and similar branched chain alkyl groups; phenyl, tolyl, xylyl and similar aryl groups; benzyl, phenethyl, or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, and similar halogenated alkyl groups. The above-mentioned other groups are most preferably methyl and phenyl.

[0013] When ingredient (a) is partially condensed with one of the ingredients (b) described below, it is preferred that ingredient (a) contains at least 0.01 wt% silicon-bonded hydroxyl groups or silicon-bonded hydrolyzable groups . Such hydrolyzable groups are exemplified by methoxy, ethoxy, propoxy and similar alkoxy; acetoxy; isopropionyloxy; and amineoxy.

[0014] Component (b) is an organopolysiloxane resin mainly composed of R ¹ ₃ SiO _1/2 units and SiO _4/2 units, and R ¹ may be a substituted or unsubstituted monovalent hydrocarbon group. Some representative groups for ^R include methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, and similar straight-chain alkyl groups; isopropyl, sec-butyl, tert-butyl, Isopentyl, tert-pentyl, neopentyl, tert-octyl and similar branched chain alkyl groups; vinyl, allyl, butenyl, pentenyl and similar alkenyl groups; phenyl, tolyl, Xylyl and similar aryl groups; benzyl, phenethyl or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl and similar halogenated alkyl groups. Methyl, vinyl and phenyl are most preferred.

[0015] When component (b) is partially condensed with component (a), it is preferred that component (b) contains at least 0.01 wt% silicon-bonded hydroxyl groups or silicon-bonded hydrolyzable groups. Such hydrolyzable groups are exemplified by methoxy, ethoxy, propoxy and similar alkoxy; acetoxy; isopropionyloxy; and amineoxy.

[0016] Although component (b) should consist essentially of R ¹ ₃ SiO _1/2 units and SiO _4/2 units, it may also contain R ¹ ₂ SiO _2/2 units and R ¹ SiO _3/2 units. Preferably the total amount of R ¹ ₃ SiO _1/2 units and SiO _4/2 units in component (b) exceeds 50 wt%, preferably 80 wt%, and more preferably 100 wt%. Most preferably, however, component (b) consists only of R ¹ ₃ SiO _1/2 units and SiO _4/2 units. The molar ratio of R ¹ ₃ SiO _1/2 units to SiO _4/2 units should be 0.5-1.5, preferably 0.5-1.0, and even more preferably 0.6-0.9. If the ratio is below the lower limit, the resulting pressure-sensitive adhesive tends to decrease in tack. If the ratio exceeds the upper limit, the pressure-sensitive adhesive will lose its adhesive strength.

[0017] As noted above, component (A) may comprise a mixture of ingredients (a) and (b), or a partial condensation product of ingredients (a) and (b). Preferably the weight ratio of components (a) and (b) in component (A) is from 1:9 to 9:1, preferably from 2:8 to 8:2, and even more preferably from 3:7 to 7:3. The partial condensation reaction of components (a) and (b) can be carried out by heating these two components. Partial condensation reactions can also be carried out in the presence of catalysts such as potassium hydroxide, barium hydroxide or similar bases; aqueous ammonia; methylamine, ethylamine, propylamine or similar amines; tetrabutyl titanate, tetraisobutyl titanate or similar titanium compounds; octyltin diacetate and similar tin compounds; and hexamethyldisilazane.

[0018] Component (B) is a crosslinking agent and is an organopolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule. In component (B), the silicon-bonding position of the hydrogen atom may be on a molecular terminal and/or on a molecular side chain. The silicon-bonded groups in component (B) may be groups other than hydrogen such as methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, and similar linear alkanes isopropyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, tert-octyl and similar branched chain alkyl groups; phenyl, tolyl, xylyl, naphthyl and Similar aryl groups; benzyl, phenethyl, or similar aralkyl groups; chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, and similar halogenated alkyl groups; and except Other substituted or unsubstituted monovalent hydrocarbon groups other than alkenyl. Methyl and phenyl are most preferred. Component (B) may have a linear, branched, cyclic or partially branched molecular structure. However, linear molecular structures are preferred. Although there is no particular limitation on the viscosity of component (B), it is preferred that this component has a viscosity at 25°C of 0.1-500000 mPa.s, preferably 1-100000 mPa.s.

[0019] The organopolysiloxane component (B) represents polymers and copolymers such as the following: both ends of the molecule are methylhydrogen polysiloxanes terminated with trimethylsiloxy groups; A copolymer of methylhydrogensiloxane and dimethylsiloxane whose ends are both endcapped with trimethylsiloxy groups; dimethylsiloxane whose molecular ends are endcapped with trimethylsiloxy groups , a copolymer of methylhydrogensiloxane and methylphenylsiloxane; a dimethylpolysiloxane whose both ends of the molecule are terminated with dimethylhydrogensiloxy groups; Copolymer of methylhydrogensiloxy-terminated methylphenylpolysiloxane and dimethylsiloxane; methylphenylpolysiloxane terminated with dimethylhydrogensiloxy at both ends of the molecule Oxanes; organopolysiloxane resins containing siloxane units of formula R ⁶ ₃ SiO _1/2 , R ⁶ ₂ HSiO _1/2 and SiO _4/2 ; containing formula R ⁶ ₂ HSiO _1/2 and SiO ₄ Organopolysiloxane resins containing siloxane units of formula R ⁶ HSiO _2/2 , R ⁶ SiO _3/2 and _{HSiO 3/2} ; and two A mixture of one or more such organopolysiloxanes. R ⁶ represents a substituted or unsubstituted monovalent hydrocarbon group other than an alkenyl group.

[0020] Component (B) is used in an amount such that 0.5 to 150.0 moles of silicon-bonded hydrogen atoms are present in the component, based on 1 mole of alkenyl groups in the component (A). Preferably 0.6-150.0 mol, more preferably 0.7-140.0 mol, and even more preferably 0.8-130.0 mol. If the content of silicon-bonded hydrogen atoms in (B) is below the lower limit, it will be difficult to provide sufficient curing of the resulting pressure-sensitive adhesive, and will have reduced cohesion and/or holding power. If the content of silicon-bonded hydrogen atoms in (B) exceeds the preferred upper limit, the resulting pressure-sensitive adhesive imparts increased peel resistance to bonded paper or tape. Over time, peel resistance will increase.

[0021] Component (C) is an ingredient used in order to improve the releasability of the adhesive tape after it has been exposed to high temperature. This component may be an aromatic amine compound and/or an organopolysiloxane containing an aromatic amino group. Although there is no particular limitation on the aromatic amine compound in (C), compounds of the following general formula are preferably used:

chemical formula 1

[0022] In Chemical Formula 1, R ² may be the same or different, and may be H, OH or a monovalent hydrocarbon group. Preferably, ^R2 is H or a monovalent hydrocarbon group. Some examples of R ² are the same monovalent hydrocarbon groups as substituted or unsubstituted monovalent hydrocarbon groups defined above for R ¹ . Preferably, these groups are straight or branched chain alkyl groups. In Chemical Formula 1, a represents an integer equal to or greater than 1.

The following are some specific examples of the aromatic amine compound of component (C) or derivatives of the compound, wherein part of the hydrogen atoms in the aromatic ring are replaced by methyl, ethyl, propyl, butyl, pentyl , heptyl, octyl, and similar straight-chain alkyls; isopropyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, tert-octyl, and similar branched-chain alkyl substitutions.

chemical formula 2

chemical formula 3

chemical formula 4

chemical formula 5

chemical formula 6

chemical formula 7

chemical formula 8

chemical formula 9

chemical formula 10

Chemical formula 11

Chemical formula 12

Chemical formula 13

Chemical formula 14

[0024] Although there is no particular limitation on component (C), the aromatic amino group-containing organopolysiloxane should have at least one silicon-bonded aromatic amino group per molecule. In this regard, the bonding position of the aromatic amino group is not particularly limited. Thus, this group can be bonded to the terminal of the molecular chain and/or to the side chain of the molecular chain. In addition, the molecular structure of the organopolysiloxane is not limited, and it may have a linear, cyclic, branched or partially branched molecular structure. The organopolysiloxane (C) containing an aromatic amino group can be represented by the following formula:

Chemical formula 15

[0025] In formula 15, R ³ can be a substituted or unsubstituted monovalent hydrocarbon group or an aromatic amino group. When ^R is hydrocarbyl, some examples of substituted or unsubstituted monovalent hydrocarbyl groups are straight chain alkyl groups, including methyl, ethyl, propyl, butyl, pentyl, heptyl and octyl; branched chain alkyl groups , such as isopropyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, neopentyl and tert-octyl; alkenyl, such as vinyl, allyl, butenyl and pentenyl; Aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; haloalkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3 - trifluoropropyl.

When R ³ is aromatic amino, it can exemplify the unsubstituted group shown below, or wherein part of the hydrogen atom in the aromatic ring is replaced by alkyl (such as straight-chain alkyl, including methyl, wherein Ethyl, propyl, butyl, pentyl, heptyl, and octyl; and branched alkyl groups such as isopropyl, sec-butyl, tert-butyl, isopentyl, tert-pentyl, neopentyl, and tert octyl) substituted with the same groups shown below.

Chemical formula 16

Chemical formula 17

Chemical formula 18

Chemical formula 19

Chemical formula 20

Chemical formula 21

Chemical formula 22

Chemical formula 23

[0027] R ³ is preferably an aromatic amino group in which some of the hydrogen atoms in the aromatic ring are not substituted by hydroxyl.

[0028] R ⁴ in Formula 15 represents a substituted or unsubstituted monovalent hydrocarbon group, which may be the same as those monovalent hydrocarbon groups described for R ³ . Among these groups, methyl and phenyl are most preferred.

[0029] In Formula 15, ^R5 represents the same aromatic amino group as those defined for ^R2 above.

[0030] In Formula 15, X represents a single bond, an oxygen atom, an alkylene group or an alkyleneoxy group. Some examples of alkylene groups that may represent X are methylene, ethylene and propylene. Some examples of alkyleneoxy groups that may represent X are methyleneoxy, ethyleneoxy and propyleneoxy.

[0031] In formula 15, m is a positive number of 1-3000, and n may be 0 or a positive number. Additionally, in Formula 15, at least one ^R group is an aromatic amino group.

[0032] The following formulas are some examples of aromatic amino group-containing organopolysiloxanes wherein m and p are positive numbers.

Chemical formula 24

Chemical formula 25

Chemical formula 26

Chemical formula 27

Chemical formula 28

Chemical formula 29

Chemical formula 30

Chemical formula 31

Chemical formula 32

Chemical formula 33

[0033] By reacting p-anilinophenol or naphthylaminophenol with an acyloxy-functional polyorganosiloxane, or in the presence of a hydrogen chloride adsorbent, by making p-anilinophenol or naphthylaminophenol and These aromatic amino group-containing organopolysiloxanes are prepared by reacting polyorganosiloxanes with silicon-bonded chlorine atoms.

[0034] Component (C) is used in an amount of 0.001-10 parts by weight, preferably 0.005-8 parts by weight, and even more preferably 0.01-5 parts by weight, per 100 parts by weight of component (A). If the amount of component (C) used is less than the preferred lower limit, it may result in decreased releasability of the adhesive tape after exposure to high temperature. On the other hand, if component (C) is used in an amount exceeding the preferred upper limit, it may impair the curability of the resulting pressure-sensitive adhesive, and may cause a decrease in the adhesive strength and tack of the adhesive.

[0035] Component (D) is a platinum-based catalyst used in the composition to facilitate the crosslinking reaction. Component (D) is typified by chloroplatinic acid, alcohol solutions of chloroplatinic acid, platinum-carbonyl complexes, platinum-alkenylsiloxane complexes, and platinum-olefin complexes. Platinum-alkenylsiloxane complex is preferred because it possesses better compatibility with component (A). Some representative platinum-alkenylsiloxane complexes are 1,3-divinyltetramethyldisiloxane and 1,1,3,3-tetravinyldimethyldisiloxane.

[0036] Component (D) is used in an amount sufficient to promote curing of the adhesive. Preferably, it is used in an amount such that the platinum metal contained in component (D) is 0.1-1000 ppm, and more preferably 1-500 ppm in weight units, based on the total weight of component (A). If component (D) is used in an amount smaller than the preferred lower limit, curing of the resulting pressure-sensitive adhesive is significantly delayed. On the other hand, if component (D) is added in an amount exceeding the preferred upper limit, it may cause coloring of the resulting pressure-sensitive adhesive.

[0037] In addition to components (A)-(D), the adhesives of the present invention may contain optional components to adjust the curing speed, such as acetylenic alcohols, including 2-methyl-3-butyne-2 -alcohol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-pentyn-3-ol and 2-phenyl-3-butyn-2-ol; enyne compounds , such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; and alkenylsiloxanes such as 1,3,5,7- Tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane .

[0038] The cure reaction modifier should be added in an amount that is most effective in regulating the rate of cure. Typically, it is used in an amount of not more than 5 parts by weight for 100 parts by weight of component (A). If it is used in an amount greater than 5 parts by weight for 100 parts by weight of component (A), the curing speed of the resulting pressure-sensitive adhesive is significantly retarded.

[0039] The adhesive of the present invention can be combined with organic solvents such as toluene, xylene, hexene, heptene, acetone, methyl ethyl ketone, and methyl iso Butyl ketone; alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, dimethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane , Phenyltrimethoxysilane, Methyltrimethoxysilane, Methyltriethoxysilane, Vinyltriethoxysilane, Allyltrimethoxysilane, Allyltriethoxysilane, 3- Glycidoxypropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane.

[0040] The silicone-based pressure sensitive adhesives of the present invention are prepared by mixing components (A)-(D), and, if desired, one or more suitable optional components. The silicon-based pressure-sensitive adhesive thus prepared is then applied to a substrate and cured at room temperature or under heating to form a pressure-sensitive adhesive layer on the surface of the substrate. Coating may be performed using a gravure coater, offset coater, offset gravure coater, roll coater, reverse roll coater, air knife coater, or curtain coater.

[0041] The adhesive tape of the present invention contains a support film and a pressure-sensitive adhesive layer formed by curing the silicone-based pressure-sensitive adhesive of the present invention. Some suitable support films include stretched or non-stretched films formed from resins such as polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate, and Nylon®. Stretch the plastic film. The support film can also consist of a plastic substrate coated with this resin. When heat resistance is desired, it is preferable to use materials such as polyimide, polyether-ether ketone (PEEK), polyethylene naphthalate (PEN), liquid crystal arylate, polyamideimide (PAI) or poly Resins such as ether sulfone (PES).

By applying a silicone-based pressure-sensitive adhesive to the support film, and then curing the applied adhesive at room temperature or under heating, a pressure-sensitive adhesive layer is formed on the surface of the support film, An adhesive tape is thereby produced. The adhesive can be applied by one of the methods described above. When the silicone-based pressure-sensitive adhesive is cured under heat on a support film, it is preferred to heat the adhesive to a temperature higher than 50°C, preferably to a temperature of 80-200°C.

Example

[0043] The silicone-based pressure sensitive adhesives and adhesive tapes of the present invention are set forth in more detail in the following practical examples and comparative examples. In these examples, the viscosity values were measured at 25°C, and the plasticity of raw rubber was measured by applying a force of 1 kg to a spherical sample of 4.2 g at 25°C for 3 minutes according to Japanese Industrial Standard (JIS) K6249 value. Adhesive strength and repeatable peelability after exposure to high temperature were determined by the methods described below.

Adhesive strength

[0044] The silicone-based pressure-sensitive adhesive was applied onto the support film of the polyimide resin in such an amount that the thickness of the formed pressure-sensitive adhesive layer after curing was about 40 micrometers. An adhesive sheet was formed by heating the resulting article at 120°C for 3 minutes. The adhesive sheet was cut into 25 mm wide strips to produce adhesive tapes. Using a rubber roller, the adhesive tape was pressure bonded to the surface of a stainless steel plate polished with No. 360 waterproof sandpaper with a force of 2 kg. The laminated product was left unmoved at room temperature for 30 minutes, and then the adhesion was measured at a constant pulling speed of 300 mm/min and a peel angle of 180°.

Repeatable peelability after exposure to high temperature

[0045] The silicone-based pressure-sensitive adhesive was applied to the support film of the polyimide resin in such an amount that a pressure-sensitive adhesive layer having a thickness of about 40 micrometers was formed after curing. An adhesive sheet was formed by heating the resulting article at 120°C for 3 minutes. The adhesive sheet was cut into 25 mm wide strips to produce adhesive tapes. Using a rubber roller, the adhesive tape was pressure bonded to the surface of a stainless steel plate polished with No. 360 waterproof sandpaper with a force of 2 kg. The resulting laminate was subjected to an aging period of 2 hours in an oven at a temperature adjustable in 10°C increments from 200°C to 300°C. The article was then removed from the oven, kept at room temperature for 30 minutes, and the tape was subjected to a peel test on a tensile testing machine at a constant pulling speed of 300 mm/min. The surface of the stainless steel plate was then visually inspected for adhesive deposit residues.

[0046] These observations were evaluated using the following criteria: (i) Repeatable peelability is considered good if repeated peeling does not leave any adhesive deposits and is marked with the symbol "○" in Tables 1-3 and (ii) if repeated peeling left adhesive deposits on the surface of the stainless steel plate, the repeatable peelability was considered unsatisfactory and indicated by a symbol "×" in Tables 1-3.

Practice Example 1

By (i) 25.6 parts by weight on the two ends of the molecule and on part of the side chain with vinyl methyl vinyl siloxane and dimethyl siloxane raw colloidal copolymer (its plasticity value 135, and the vinyl content is 0.2wt%); (ii) 54.6 parts by weight of ((CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit composed of (CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit ratio is 0.8mol) 60wt% xylene dilute solution of methylpolysiloxane resin; Siloxane (with a viscosity of 20 mPa.s and a silicon-bonded hydrogen atom content of 1.55% by weight); (iv) 0.2 parts by weight of 2-methyl-3-butyn-2-ol; (v) 0.2 parts by weight Parts of dimethylsiloxane containing p-anilinophenoxy group represented by the following formula;

and (vi) 69.2 parts by weight toluene to prepare a mixture. Combine the resulting mixture with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum complex, where units by weight are based on methylvinylsiloxane and dimethyl The total weight of the raw gelatinous copolymer of base siloxane and methyl polysiloxane resin, the metal platinum is 100ppm. As a result, a silicone-based pressure-sensitive adhesive containing 40% by weight of an organopolysiloxane component was produced. The resulting pressure sensitive adhesive was used to prepare adhesive tapes. The adhesive strength and re-peelability of the adhesive tape were tested, and it was proved to have good test results.

Table 1 shows the test results.

Comparative example 1

[0048] In this example, the silicone-based pressure-sensitive adhesive is obtained in the same manner as in Practice Example 1, except that 0.2 parts by weight of toluene is used instead of 0.2 parts by weight of p-anilinophenoxy of dimethylsiloxane. The resulting silicone-based pressure-sensitive adhesives were used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 1 shows the results of this evaluation.

Table 1 Practice Example 1 Comparative example 1 Adhesive strength (N/m) 245 270 Repeatable peelability, degree Observation of Repeatable Peelability 200℃ ○ ○ 210°C ○ ○ 220°C ○ ○ 230°C ○ ○ 240°C ○ ○ 250°C ○ ○ 260°C ○ x 270°C ○ x 280°C ○ x 290°C x x

Practice Example 2

[0049] by (i) 25.6 parts by weight of raw colloidal dimethyl polysiloxane with vinyl at both ends of the molecule; (ii) 54.6 parts by weight of (CH ₃ ) ₃ SiO _1/2 units and SiO ₄ ((CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit ratio is 0.8mol) 60wt% xylene dilute solution of methyl polysiloxane resin of _/2 unit composition; (iii) 0.2 parts by weight in Methylhydrogenpolysiloxane (its viscosity is 20mPa.s, and the content of hydrogen atoms bonded to silicon is 1.55wt%) with trimethylsiloxy terminated at both ends of the molecule; (iv) 0.2 parts by weight 2-methyl-3-butyn-2 alcohol; (v) 0.2 parts by weight of dimethylsiloxane containing p-anilinophenoxy group represented by the following formula;

and (vi) 69.2 parts by weight toluene to prepare a mixture. Combine the resulting mixture with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum complex, where the units by weight are based on the gum-like dimethylpolysiloxane and the total weight of the methyl polysiloxane resin, the metal platinum is 100 ppm. As a result, a silicone-based pressure-sensitive adhesive containing 40% by weight of an organopolysiloxane component was produced. The resulting pressure sensitive adhesive was used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 2 shows the evaluation results.

Comparative example 2

In this embodiment, obtain silicone-based pressure-sensitive adhesive in the same manner as in practical example 2, except that 0.2 parts by weight of toluene is used instead of 0.2 parts by weight of p-anilinophenoxy-containing Dimethicone. The resulting silicone-based pressure-sensitive adhesives were used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 2 shows the results of this evaluation.

Table 2 Practice Example 2 Comparative example 2 Adhesive strength (N/m) 291 325 Repeatable peelability, degree Observation of Repeatable Peelability 200℃ ○ ○ 210°C ○ ○ 220°C ○ ○ 230°C ○ x 230°C ○ x 250°C ○ x 260°C x x

Practice Example 3

By (i) 25.6 parts by weight on the two ends of the molecule and on part of the side chain with vinyl methyl vinyl siloxane and dimethyl siloxane raw colloidal copolymer (its plasticity value 135, and the vinyl content is 0.07wt%); (ii) 54.6 parts by weight ((CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit composed of (CH ₃ ) ₃ SiO 1/2 unit and SiO _4/2 unit _4/2 unit ratio is 0.8mol) 60wt% xylene dilute solution of methylpolysiloxane resin; Siloxane (which has a viscosity of 20 mPa.s and a silicon-bonded hydrogen atom content of 1.55% by weight); (iv) 0.2 parts by weight of 2-methyl-3-butyn-2-ol; and (v) 0.6 A mixture of aromatic amines represented by the following formula in parts by weight:

Chemical formula 36

where R is a mixture _of H and tert- _C8H17 .

Combining the resulting mixture with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum complex, wherein by weight, based on methylvinylsiloxane The total weight of the raw gel-like copolymer of dimethylsiloxane and methylpolysiloxane resin, and metal platinum is 100ppm. As a result, a silicone-based pressure-sensitive adhesive containing 40% by weight of an organopolysiloxane component was produced. The resulting pressure-sensitive adhesive was used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 3 shows the evaluation results.

Comparative example 3

[0053] In this example, a silicone-based pressure-sensitive adhesive was obtained in the same manner as in Practical Example 3, except that 0.6 parts by weight of toluene was used instead of 0.6 parts by weight of the mixture of aromatic amines. The resulting silicone-based pressure-sensitive adhesives were used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 3 shows the results of this evaluation.

Practice Example 4

By (i) 25.6 parts by weight on the two ends of the molecule and on the part of the side chain with vinyl methyl vinyl siloxane and dimethyl siloxane raw colloidal copolymer (its plasticity value is 135, and the vinyl content is 0.07wt%); (ii) 54.6 parts by weight ((CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit composed of (CH ₃ ) ₃ SiO 1/2 unit and SiO _4/2 unit _4/2 unit ratio is 0.8mol) 60wt% xylene dilute solution of methylpolysiloxane resin; Siloxane (with a viscosity of 20 mPa.s and a silicon-bonded hydrogen atom content of 1.55% by weight); (iv) 0.2 parts by weight of 2-methyl-3-butyn-2-ol; (v) 0.3 parts by weight Parts of dimethylsiloxane containing p-anilinophenoxy represented by the following formula;

Chemical formula 37

(vi) 0.3 parts by weight of a mixture of aromatic amines of the average formula:

Chemical formula 38

wherein R is a mixture of H and tert _{-C8H17 ;} and (vii) 68.8 parts by weight of toluene to prepare the mixture. Combine the resulting mixture with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum complex, where units by weight are based on methylvinylsiloxane and dimethyl The total weight of the raw colloidal copolymer of base siloxane and methylpolysiloxane resin, and the metal platinum is 100ppm. As a result, a silicone-based pressure-sensitive adhesive containing 40% by weight of an organopolysiloxane component was produced. The resulting pressure sensitive adhesive was used to prepare adhesive tapes. The adhesive strength and repeated peelability of the adhesive tape were evaluated. Table 3 shows the evaluation results.

table 3 Practice Example 3 Practice Example 4 Comparative example 3 Adhesive strength (N/m) 226 257 245 Repeatable peelability, degree Observation of Repeatable Peelability 200℃ ○ ○ ○ 210°C ○ ○ ○ 220°C ○ ○ ○ 230°C ○ ○ ○ 240°C ○ ○ ○ 250°C ○ ○ x 260°C ○ ○ x 270°C ○ ○ x 280°C ○ ○ x 290°C x x x

[0055] The reproducibility evaluation after exposure to high temperature showed that in the case of practical examples 1 and 2, using component (C) in the form of an organopolysiloxane having an aromatic amino group, the After the adhesive sheet was peeled off, easily visible marks were left on the surface of the stainless steel plate. This color change is considered to be caused by the presence of an organopolysiloxane having an aromatic amino group which is prone to color change. On the contrary, in Practical Example 4, using the component (C) in the form of a combination of an aromatic amine compound and an organopolysiloxane having an aromatic amino group, the change in color was limited, and the adhesive was peeled off from the stainless steel plate. After cleaning the sheet, practically no marks are left on the surface of the stainless steel plate.

[0056] The adhesive tape of the present invention possesses good repeatable peelability after exposure to high temperature and can be used as a heat treatment masking tape in the solder reflow process used in the manufacture of printed circuit boards.

Claims (6)

1. A silicone-based pressure-sensitive adhesive comprising: (A) The product of the partial condensation of components (a) and (b) or a mixture of components (a) and (b), wherein component (a) is a gum-like organic polymer having an average of at least one alkenyl group per molecule. siloxane, and component (b) is an organopolysiloxane resin mainly composed of R ¹ ₃ SiO _1/2 units and SiO _4/2 units, wherein R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, and wherein R ¹ ₃ The molar ratio of SiO _1/2 unit to SiO _4/2 unit is 0.5-1.5; (B) An organopolysiloxane having an average of at least two silicon-bonded hydrogen atoms per molecule, wherein the silicon-bonded hydrogen atoms are present in an amount of 0.5 to 150.0 mol/mol of the alkenyl group in component (A) The dosage exists; (C) an aromatic amine compound and/or an organopolysiloxane containing an aromatic amino group, relative to 100 parts by weight of component (A), its amount is 0.001-10 parts by weight; and (D) A platinum catalyst used in an amount sufficient to cure the adhesive. 2. The silicone-based pressure-sensitive adhesive of claim 1, wherein the aromatic amine compound of component (C) has the general formula: wherein each R ² is H, OH, or a monovalent hydrocarbon group; and a is an integer equal to at least 1. 3. The silicone-based pressure sensitive adhesive of claim 1, wherein the organopolysiloxane of component (C) has the general formula: Wherein ^R3 is a substituted or unsubstituted monovalent hydrocarbon group or an aromatic amino group; ^R4 is a substituted or unsubstituted monovalent hydrocarbon group; ^R5 is an aromatic amino group; X is a single bond, an oxygen atom, an alkylene group or an alkyleneoxy group ; m is a positive number; n is 0 or a positive number; the condition is that when n is 0, at least one R ³ group is an aromatic amino group. 4. The silicone-based pressure sensitive adhesive of claim 1, further comprising at least one cure reaction modifier. 5. The silicone-based pressure-sensitive adhesive of claim 1, further comprising at least one solvent for components (A)-(D). 6. An adhesive tape comprising a support film and a pressure-sensitive adhesive layer, wherein the adhesive layer is formed by curing the silicone-based pressure-sensitive adhesive according to claim 1.