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WO2025056403A1 - Composition de revêtement aqueuse comprenant un copolymère acrylique dispersé - Google Patents

Composition de revêtement aqueuse comprenant un copolymère acrylique dispersé Download PDF

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Publication number
WO2025056403A1
WO2025056403A1 PCT/EP2024/074746 EP2024074746W WO2025056403A1 WO 2025056403 A1 WO2025056403 A1 WO 2025056403A1 EP 2024074746 W EP2024074746 W EP 2024074746W WO 2025056403 A1 WO2025056403 A1 WO 2025056403A1
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WIPO (PCT)
Prior art keywords
coating composition
monomer mixture
monomer
ethylenically unsaturated
beverage
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English (en)
Inventor
Robert Callow
Brian David Milligan
Daniel Wesley
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Akzo Nobel Coatings International BV
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Akzo Nobel Coatings International BV
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Publication of WO2025056403A1 publication Critical patent/WO2025056403A1/fr
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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
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D151/00—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers
    • C09D151/003—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
    • C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
    • C08F265/06—Polymerisation of acrylate or methacrylate esters on to polymers thereof

Definitions

  • the present invention relates to an aqueous coating composition comprising a dispersed acrylic copolymer, suitable for coating metal substrates of food and beverage packaging such as food and beverage cans or parts thereof, to a method to coat a metal food or beverage can or a part thereof with such coating composition, and to an article coated with such coating composition.
  • Food and beverage metal containers (cans) and its parts are typically coated on the inside and the outside to protect the metal substrate from degradation and to protect the food or beverage contained therein from deterioration.
  • Some canned foods and beverages are highly acidic and represent a harsh environment for the metal substrate. The coating therefore should meet stringent requirements with respect to adhesion to the substrate, chemical resistance, and food safety.
  • Can coatings produced without adding bisphenol A, bisphenol F, bisphenol S, aromatic glycidyl ether compounds, or epoxy resins or other compounds based thereon are known.
  • coatings based on waterborne acrylic technology are known.
  • Acrylic-based can coatings are relatively soft and have low chemical resistance.
  • Increasing the glass transition temperature of such coatings by using (meth)acrylic co-monomers with a relatively high glass transition temperature may lead to stiff and brittle coatings with insufficient flexibility to withstand any deformations during production and transportation.
  • a relatively high glass transition temperature is, however, needed to avoid so-called flavor scalping.
  • Flavor scalping is the loss of quality of the packaged food or beverage due to volatile flavors being absorbed by the packaging or the food or beverage absorbing undesirable flavors from its packaging. The requirements to minimize flavor scalping and to have high flexibility are thus somewhat contradictory. It is therefore difficult to provide a coating composition that satisfies both requirements.
  • Acrylic-based can coatings often comprise styrene or other aromatic co-monomers to increase hardness of the coating. There is a desire to avoid styrene or other aromatic co-monomers in producing polymers for food-contact coatings.
  • WO 2018/013766 is described an aqueous coating composition for food and beverage containers comprising an emulsified acrylic latex polymer obtained by emulsion polymerizing ethylenically unsaturated monomers in the presence of an emulsifying polymer with a number average molecular weight of at least 8,500.
  • the cured film of the coating composition of WO 2018/013766 has at glass transition temperature of at least 40 °C.
  • the coating compositions exemplified in WO 2018/013766 all comprise acrylic polymers comprising styrene monomers.
  • WO 2018/085052 is described an aqueous inside spray coating composition suitable for use in forming a food-contact coating of a food or beverage can that is substantially free of bisphenol A.
  • the coating composition comprises a dispersed acid- or anhydride-functional acrylic polymer and a nitrogen-containing carboxyl-reactive crosslinker.
  • the coating composition of WO 2018/085052 is substantially free of styrene.
  • aqueous acrylic-based coating compositions for food and beverage cans that are free of styrene and preferably also free of other aromatic monomers and have sufficiently high hardness and flexibility.
  • aqueous acrylic-based coating compositions that are suitable for coil coating a metal substrate that can be used for forming beverage can ends. Coil coated metal substrates for beverage can ends are cured for only a few seconds at a typical bake temperature in the range of from 180-250 °C (peak metal temperature).
  • a dispersed styrene-free acrylic copolymer can be provided that, when used as binder polymer in an aqueous coating composition for food and beverage metal packaging, results in a coating with sufficient hardness, high flexibility, and good adhesion to the metal substrate.
  • the coating composition is, moreover, suitable to be used for coating metal beverage can ends or for coating a metal substrate to be formed into beverage can ends by means of coil coating.
  • the invention provides in a first aspect an aqueous coating composition
  • a dispersed acrylic copolymer wherein the acrylic copolymer is obtained by emulsion polymerization of an ethylenically unsaturated monomer component in the presence of an aqueous dispersion of an emulsifying polymer, wherein the aqueous dispersion of the emulsifying polymer is obtained by: a) solution polymerizing a first monomer mixture to obtain an acid-functional polymer in solution, wherein the first monomer mixture consists of:
  • (2iii) glycidyl methacrylate in an amount of at most 8.0 wt.%, wherein all wt.% are based on the total weight of ethylenically unsaturated monomers in the second monomer mixture, and wherein the second monomer mixture is free of styrene.
  • the invention provides a method to coat a metal food or beverage can, a part of a metal food or beverage can, or a metal substrate to be formed into a metal food or beverage can or a part of a metal food or beverage can, comprising applying the coating composition according to the first aspect of the invention to at least a part of a metal surface of the can, the part thereof, or the metal substrate to be formed into the metal can or the part thereof, and curing the applied coating composition.
  • the invention provides an article coated with a coating composition according to the first aspect of the invention, wherein the article is a beverage can end or a beverage can body, preferably a beverage can end.
  • the coating composition according to the present invention is an aqueous coating composition comprising a dispersed acrylic copolymer.
  • the acrylic copolymer acts as a film-forming binder polymer that forms a coating film upon curing.
  • the acrylic copolymer is obtained by emulsion polymerization of an ethylenically unsaturated monomer component in the presence of an aqueous dispersion of an emulsifying polymer.
  • the aqueous dispersion of the emulsifying polymer is obtained by: a) solution polymerizing a first monomer mixture of ethylenically unsaturated monomers to obtain an acid-functional polymer in solution; b) at least partially neutralizing the acid-functional polymer obtained in a) using a neutralizing agent to obtain an at least partially neutralized acid-functional polymer; and c) dispersing the at least partially neutralized acid-functional polymer in water.
  • the dispersed acrylic copolymer is thus obtained by a two-stage polymerization process wherein the first stage comprises solution polymerization of the first monomer mixture and the second stage comprises emulsion polymerization of the ethylenically unsaturated monomer component (the second monomer mixture) in the presence of the emulsifying polymer of the first stage after it has been at least partly neutralized and dispersed in water.
  • solution polymerization step a) of the preparation of the aqueous dispersion of emulsifying polymer a first monomer mixture of ethylenically unsaturated monomers is polymerized.
  • the first monomer mixture consists of:
  • the first monomer mixture is free of styrene.
  • the first monomer mixture is free of any aromatic ethylenically unsaturated monomer, such as aromatic (meth)acrylic monomers like benzoate (meth)acrylate.
  • the first monomer mixture does not comprise a further ethylenically unsaturated monomer (1 iii).
  • the first monomer mixture comprises methacrylic acid and methyl methacrylate as the only monomers, i.e., in the range 5 wt.% to 20 wt.% of methacrylic acid and in the range of from 80 wt.% to 95 wt.% of methyl methacrylate.
  • the first monomer mixture comprises a further ethylenically unsaturated monomer (1 iii).
  • the further ethylenically unsaturated monomer (1 iii) may be a mixture comprising more than one further ethylenically unsaturated monomer.
  • the further ethylenically unsaturated monomer (1 iii) comprises a (meth)acrylate monomer, more preferably comprises a (meth)acrylate monomer selected from the group consisting of cyclohexyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and a mixture of two or more thereof.
  • the further ethylenically unsaturated monomer (1 iii) consists of one or more (meth)acrylate monomers selected from the group consisting of cyclohexyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-hydroxyethyl (meth)acrylate, and hydroxypropyl (meth)acrylate, more preferably consists of one or more methacrylate monomers selected from the group consisting of a cyclohexyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, and a mixture of two or more thereof.
  • Polymerization step a) is a solution polymerization step.
  • Solution polymerization is well-known in the art. Any process conditions known in the art may suitably be applied.
  • monomers in a liquid carrier comprising an organic solvent or organic solvent mixture are polymerized in the presence of a free radical initiator.
  • the organic solvent(s) are miscible with water.
  • suitable solvents include glycol ethers such as di(propylene glycol) methyl ether.
  • the liquid carrier in polymerization step a) may comprise water in an amount less than 50 wt.%, preferably less than 20 wt.%, more preferably less than 10 wt.%.
  • the weight ratio of first monomer mixture to liquid carrier is in the range of from 40/60 to 80/20, preferably of from 45/65 to 70/30.
  • Solution polymerization is typically carried out at a temperature in the range of from 80 °C to 150 °C, preferably of from 100 °C to 130 °C.
  • Initiators suitable for solution polymerization of ethylenically unsaturated monomers are well known in the art. Any suitable initiator may be used in any suitable amount.
  • an acid-functional polymer in solution is obtained.
  • the acidfunctional polymer preferably has an acid value of at least 40 mg KOH/g polymer, more preferably at least 50 mg KOH/g polymer, even more preferably at least 70 mg KOH/g polymer.
  • An acid value of in the range of from 80 to 125 mg KOH/g polymer is particularly preferred.
  • Reference herein to acid value is to calculated acid value (calculated from the amounts of monomers used in the solution polymerization).
  • the acid-functional polymer has a number average molecular weight in the range of from 5,000 g/mol to 60,000 g/mol, more preferably of from 10,000 g/mol to 50,000 g/mol, even more preferably of from 15,000 g/mol to 40,000 g/mol.
  • the polydispersity index of the acid-functional polymer is at most 3.0, more preferably at most 2.5. Reference herein to number average molecular weight is to the number average molecular weight determined by size exclusion chromatography using polystyrene standards according to ISO 16014.
  • the polydispersity index (the ratio of number average molecular weight and weight average molecular weight) is calculated as the quotient of number average molecular weight and weight average molecular weight, both determined by size exclusion chromatography using polystyrene standards according to ISO 16014.
  • the acid-functional polymer has a glass transition temperature (calculated Fox glass transition temperature) of at least 40 °C, more preferably in the range of from 45 °C to 150 °C, even more preferably of from 50 °C to 130 °C.
  • the following glass transition temperatures are used for the homopolymers of the following monomers: methacrylic acid: 505 K (228 °C) methyl methacrylate: 378 K (105 °C) cyclohexyl methacrylate: 365 K (92 °C) n-Butyl methacrylate: 293 K (20 °C) tertiary-Butyl methacrylate: 391 K (118 °C)
  • the glass transition temperature of its homopolymer as given in J. Brandrup, E.H. Immergut, and E.A. Guile (eds), Polymer Handbook, 4 th ed., John Wiley & Sons, Inc., 1999, is used.
  • the acid-functional polymer obtained in step a) is at least partially neutralized using a neutralizing agent to obtain an at least partially neutralized acid-functional polymer.
  • the neutralizing agent may be any suitable neutralization agent, preferably an amine. Any suitable amine may be used, preferably a tertiary amine. An example of a suitable amine is dimethylaminoethanol. Preferably at least 40%, more preferably at least 50%, of any acidic functional groups in the acid-functional polymer are neutralized.
  • dispersion step c) the at least partially neutralized acid-functional polymer obtained in b) is dispersed in water to obtain the aqueous dispersion of the emulsifying polymer.
  • the amount of water is such that the solids content of the dispersion is in the range of from 25 wt.% to 40 wt.%, more preferably of from 30 wt.% to 35 wt.%.
  • an ethylenically unsaturated monomer component is subjected to emulsion polymerization in the presence of the aqueous dispersion of the emulsifying polymer.
  • Emulsion polymerization is typically done in water in the presence of a free radical initiator, preferably a water-soluble free radical initiator.
  • a free radical initiator preferably a water-soluble free radical initiator.
  • Emulsion polymerization is well known in the art. Any suitable conditions for emulsion polymerization may be used.
  • the emulsion polymerization is preferably carried out at a temperature in the range of from 30 °C to 100 °C.
  • Any suitable free radical initiator may be used, such as for example a peroxide, a percarbonate, a perphosphate, a persulfate, or combinations thereof.
  • a free radical initiator can be used alone or as the oxidizing component of a redox system further comprising a reducing component (accelerator), such as ascorbic acid, malic acid, oxalic acid, lactic acid, or an alkali metal sulfite.
  • a promoter may be used, such as a chloride or a sulfate salt of cobalt, iron, nickel or copper, preferably iron sulfate.
  • the ethylenically unsaturated monomer component is a second monomer mixture comprising (2i) methyl methacrylate in an amount of at most 45 wt.%, (2ii) ethyl acrylate in an amount of at least 47 wt. %, and, optionally, (2iii) glycidyl methacrylate in an amount of at most 8.0 wt%. All wt.% are based on the total weight of ethylenically unsaturated monomers in the second monomer mixture.
  • the second monomer mixture is free of styrene.
  • the second monomer mixture is free of any aromatic ethylenically unsaturated monomer, such as aromatic (meth)acrylic monomers like benzoate (meth)acrylate.
  • the second monomer mixture may comprise ethylenically unsaturated monomers other than (2i), (2ii), and (2iii), preferably in an amount of at most 10 wt%, even more preferably at most 5 wt.%, or even at most 1 wt.%, based on the total weight of ethylenically unsaturated monomers.
  • the second monomer mixture is free of ethylenically unsaturated monomers other than (2i), (2ii), and (2iii), and thus consists of methyl methacrylate in an amount of at most 45 wt.%, ethyl acrylate in an amount of at least 47 wt. %, and, optionally, glycidyl methacrylate in an amount of at most 8.0 wt%.
  • the second monomer mixture comprises glycidyl methacrylate in an amount in the range of from 0 to 5.0 wt%. In one embodiment, the second monomer mixture is free of glycidyl methacrylate. In another embodiment, the second monomer mixture comprises glycidyl methacrylate in an amount in the range of from 1 .0 to 5.0 wt%.
  • the second monomer mixture preferably comprises at least 20 wt.% methyl methacrylate, based on the total weight of ethylenically unsaturated monomers in the second monomer mixture.
  • the second monomer mixture comprises in the range of from 20 to 45 wt.% methyl methacrylate, in the range of from 50 to 80 wt.% ethyl acrylate, in the range of from 0 to 5.0 wt.% glycidyl methacrylate, and in the range of from 0 to 1 wt.% ethylenically unsaturated monomers other than methyl methacrylate, ethyl acrylate, and glycidyl methacrylate.
  • the acrylic copolymer preferably comprises in the range of from 20 wt.% to 60 wt.% of the acidfunctional polymer and in the range of from 40 wt.% to 80 wt.% of a polymer polymerized from the ethylenically unsaturated monomer component, i.e., the second monomer mixture.
  • an aqueous coating composition comprising the dispersed acrylic copolymer prepared as described above, provides a coating with high flexibility and high pencil hardness after curing.
  • the coating composition preferably comprises in the range of from 5 wt.% to 65 wt.% of the acrylic polymer, more preferably of from 10 wt.% to 55 wt.%, based on the total solids weight of the coating composition (w/w solids on solids).
  • the coating composition may comprise a crosslinker.
  • the crosslinker may be any crosslinker reactive with any functional group on the acrylic copolymer, such as for example any carboxyl of hydroxyl functional groups on the acrylic copolymer.
  • the crosslinker may be a compound that self-crosslinks and forms a network independently of the acrylic copolymer.
  • Suitable crosslinkers include phenol formaldehyde resins (also referred to as phenoplasts or phenolic resins), aminoplast resins, polyisocyanate, and beta-hydroxyalkyl amides.
  • Phenol formaldehyde resins are condensation products of aldehydes with phenols and include novolacs and resoles.
  • Aminoplast resins are condensation products of aldehydes, such as formaldehyde, with amino or amido group-containing compounds, such as urea, melamine and benzoguanamine.
  • Preferred aminoplast resins are benzoguanamine-formaldehyde resins, melamine-formaldehyde resins, urea-formaldehyde resins.
  • Suitable polyisocyanate crosslinkers include blocked or non-blocked diisocyanates, including its trimers.
  • the second monomer is free of glycidyl methacrylate and the coating composition comprises a beta-hydroxyalkyl amide as crosslinker.
  • the first and second monomer mixture are free of glycidyl methacrylate.
  • the amount of beta-hydroxyalkyl amide in this embodiment is preferably in the range of 1 to 10 wt.% of beta- hydroxyalkyl amide.
  • the coating composition may further comprise pigments, and/or one or more additives conventionally used in coating compositions to facilitate manufacturing, processing, handling, and application of the coating composition and/or to improve a particular property of a coating composition or a cured coating resulting therefrom.
  • Pigments may include color pigments and extender pigments (often referred to as fillers).
  • Additives may include catalysts, dyes, lubricants, anticorrosive agents, flow control agents, thixotropic agents, dispersing agents, antioxidants, adhesion promoters, light stabilizers, surfactants, and mixtures thereof.
  • the coating composition is an aqueous coating composition and preferably comprises in the range of from 25 to 90 wt.% water, more preferably in the range of from 30 to 80 wt.% water, based on the total weight of the coating composition.
  • the coating composition preferably has a total solids content om the range of from 10 to 70 wt.%, more preferably of from 20 to 50 wt.% based on the weight of the coating composition.
  • the invention in a second aspect relates to a method to coat a metal food or beverage can, a part of a metal food or beverage can, or a metal substrate to be formed into a metal food or beverage can or a part of a metal food or beverage can, comprising applying the coating composition according to the first aspect of the invention to at least a part of a metal surface of the can, the part thereof, or the metal substrate to be formed into the metal can or the part thereof, and curing the applied coating composition.
  • the applied coating composition may be cured in an oven. Cure conditions may vary depending on the method of application and the intended end use. Oven temperatures typically range of from 100 to 300 °C, preferably of from 150 to 260 °C. Oven times may vary from 5 seconds to 10 minutes.
  • the coating composition is particularly useful for coating food and beverage cans (e.g., two- piece cans, three-piece cans, etc.). Two-piece cans are manufactured by joining a can body (typically a drawn metal body) with a can end (typically a drawn metal end).
  • the coating composition of the present invention is suitable as a food-contact coating and may advantageously be used on the inside of food or beverage cans or parts thereof. They are particularly suitable to be applied on the beverage can ends by a coil coating operation.
  • the invention relates to an article coated with a coating composition according to the first aspect of the invention, wherein the article is a beverage can end or a beverage can body, preferably a beverage can end.
  • the film hardness of the dried coatings on beverage can ends tooled from the coated panels was determined according to the pencil hardness test of ISO 15184.
  • the coating integrity after exposure to heat and pressure with a liquid was determined by testing blush after such exposure.
  • Beverage can ends tooled from the coated panels were submersed in a solution of 2 wt% citric acid in water of 121 ° C. The coated substrate was then tested for blush.
  • Beverage can ends tooled from the coated panels were submersed for 30 minutes in a solution of 4 wt% citric acid in water of 121 ° C for 30 minutes. The coated substrate was then tested for blush.
  • Beverage can ends tooled from the coated metal panels were submerged in an electrolyte solution (1 wt% NaCI in water) and subjected to an enamel rater test wherein the current passing through the metal panel is determined when an electric potential is applied over it.
  • a coating showing an enamel rating below current below 2 mA is considered a good coating (flexible and substantially free of defects).
  • Various samples of emulsifying polymer were prepared by solution polymerizing a first monomer mixture consisting of methyl methacrylate (MMA), methacrylic acid (MAA), and a third monomer “X”.
  • Monomer “X” was a different monomer for each sample.
  • Table 1 the various monomers “X” used in the various samples are shown. The weight percentages of the three monomers in the monomer mixture was for all samples: 23.2 wt.% MMA, 13.9 wt.% MAA, and 62.9 wt.% monomer “X”.
  • the solution polymerization was carried out in dipropylene glycol methyl ether (DowanolTM DPM, ex. Dow) as solvent (55 wt.% monomers and 45 wt.% solvent).
  • the solvent was heated to 125 °C.
  • Trigonox 21 tert-Butyl peroxy-2-ethylhexanoate
  • the first monomer mixture was added at a constant rate over 90 minutes whilst maintaining the temperature at 125 °C, until a target solids content of 55 wt.% was achieved.
  • the resulting polymer solution was then cooled to 90 °C.
  • the calculated acid value was 90 mg KOH/g polymer for all samples of emulsifying polymer. Batch sizes, feed rates, and all other parameters were kept constant in the preparation of all samples and were controlled by a high throughput experimentation robot.
  • the calculated Fox glass transition temperature of the emulsifying polymers is given in Table 1.
  • the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the emulsifying polymers were determined according to ISO 16014 using THF as eluent (10 wt.% polymer in THF) and using UV detection (254 nm).
  • the number average molecular weight and the polydispersity index (PDI), i.e. , the quotient of Mw and Mn are given in Table 1. Properties of the emulsifying polymers
  • the thus-obtained solutions were applied on an A4-sized aluminium panel using a wire-wound application bar.
  • the coated panels were then dried in an oven set to 10 seconds bake at a peak metal temperature of 240 °C.
  • the amount of polymer solution applied was such that a film weight of 10-12 grams/m 2 was obtained.
  • Pencil hardness, retort resistance, and enamel rating of the cured films was determined as described hereinabove. The results of the pencil hardness and retort resistance tests are shown in Table 1. The enamel rating was unacceptable for all films of emulsifying polymers as such (above 80 mA, most of them even above 170 mA; a rating below 2 mA is considered acceptable). Table 1 . Emulsifying polymers and properties of cured film of such polymers a Fox calculated Tg
  • Dispersed acrylic copolymers were prepared from emulsifying polymers EP 5, EP 11 and EP 15 of Example 1 as follows.
  • the solution of emulsifying polymer (55 wt.% non-volatile material) was cooled to 90 °C.
  • DMAE dimethylaminoethanol
  • PG propylene glycol
  • the dispersions were further cooled to 50 °C under stirring whilst bubbling nitrogen through it. The thus-obtained dispersions were approximately water viscous, and all appeared transparent.
  • the amounts of emulsifying polymer solution, DMAE, PG, and water are given in Table 2 (items 1 to 4).
  • Ascorbic acid, de-ionized water, further DMAE, and FeSO 4 were then added to the dispersion in the amounts indicated in Table 2 (items 5 to 8).
  • the mixture was held for 15 minutes at 50 °C under stirring whilst bubbling nitrogen through it.
  • the second monomer mixture (items 9 to 11 in Table 2) was then added and stirring was continued for 30 minutes. Further water and a radical polymerization initiator (items 12 and 13 in Table 2) were gradually added. The temperature rise due to the exothermal reaction was monitored and the reaction mixture was cooled to room temperature after no exothermal reaction was observed anymore.
  • the second monomer mixture contained methyl methacrylate (MMA), optionally glycidyl methacrylate (GMA), and a monomer Y.
  • Monomer Y was selected from various (meth)acrylic monomers. The type of monomer Y, and the amounts of the monomers are given in Table 3. The following monomers Y were used: n-Butyl acrylate (BA); Benzyl methacrylate (Benzyl MA); Ethyl acrylate (EA); and 2-Hydroxypropyl acrylate (HPA). Table 3 gives the weight percentage of each monomer in the second monomer mixture (MMA, optionally GMA, and monomer Y) based on the total weight of the second monomer mixture.
  • BA n-Butyl acrylate
  • Benzyl MA Benzyl methacrylate
  • EA Ethyl acrylate
  • HPA 2-Hydroxypropyl acrylate
  • the second monomer mixture forms 60 wt.% of the solid weight of the final latex.
  • the emulsifying polymer forms 40 wt% of the solid weight of the final latex.
  • Each latex had a non- volatile material content of 35 wt.% and a VOC (volatile organic content) of 500 g/kg.
  • each of the latices prepared in Example 2 was added to a blending vessel.
  • Dowanol DPM Dipropylene glycol monomethyl ether
  • BYK 333 polyether-modified polydimethylsiloxane
  • the thus-obtained coating compositions were applied on acid-washed A4-sized aluminium panels using a wire-wound application bar.
  • the coated panels were then dried in an oven set to 10 seconds bake at a peak metal temperature of 240 °C.
  • the amount of polymer solution applied was such that a film weight of 10-12 grams/m 2 was obtained.
  • Pencil hardness, retort resistance, and enamel rating of the cured films was determined as described hereinabove.
  • the results of the tests for pencil hardness, enamel rating (ER), and retort resistance are shown in Table 3. As can be seen from Table 3, the ER performance of all coating compositions, except for coating compositions 4, 5, 10, 14, 28, and 31 were unacceptable (an ER rating of less than 2 mA is considered acceptable). Coating compositions 4 and 10, however, do not show sufficient pencil hardness (a pencil hardness of at least 3H is considered sufficient). Only coating compositions 5, 14, 28, and 31 combine a good ER rating with good hardness and acceptable retor
  • a solution of emulsifying polymer was prepared as described in Example 1 for EP 5.
  • a dispersed acrylic copolymer (latex) was prepared from EP5 as described in Example 2.
  • the second monomer mixture contained 25 wt.% methyl methacrylate (MMA), 4 wt.% glycidyl methacrylate (GMA), and 71 wt.% ethyl acrylate (EA).
  • Two different coating compositions were prepared from the latex: one with a phenol formaldehyde resin as crosslinker and one without crosslinker.
  • Coating composition without crosslinker The latex was added to a blending vessel. Dowanol DPM (Dipropylene glycol monomethyl ether) and polyether-modified polydimethylsiloxane (BYK 333) were added in such amounts that the VOC was 750 g/kg and the Byk 333 concentration was 0.1 wt. % on total weight of the (wet) coating composition. Finally, 3 wt. % (on solids) of a wax was added.
  • Dowanol DPM Dipropylene glycol monomethyl ether
  • BYK 333 polyether-modified polydimethylsiloxane
  • Coating composition with crosslinker The latex was added to a blending vessel. Dowanol DPM (Dipropylene glycol monomethyl ether) and polyether-modified polydimethylsiloxane (BYK 333) were added in such amounts that the VOC was 750 g/kg and the Byk 333 concentration was 0.1 wt.% on total weight of the (wet) coating composition. Finally, 3 wt.% of a wax and 4 wt.% phenol formaldehyde resin (both on solids) was added as crosslinker. The coating compositions were applied on acid-washed A4-sized aluminium panels using a wirewound application bar. The coated panels were then dried in an oven set to 10 seconds bake at a peak metal temperature of 240 °C. The amount of polymer solution applied was such that a film weight of 10-12 grams/m 2 was obtained.
  • Dowanol DPM Dipropylene glycol monomethyl ether
  • BYK 333 polyether-modified poly
  • Pencil hardness, retort resistance, and enamel rating (ER) of the cured films was determined as described hereinabove.
  • the results of the tests for pencil hardness, enamel rating (ER), and retort resistance are shown in Table 4.
  • Table 4 As can be seen from Table 4, the presence of a crosslinker results in improved enamel rating (an indication of flexibility and coating integrity) and in improved retort resistance.
  • An emulsifying polymer was prepared by solution polymerizing a first monomer mixture consisting of 23.2 wt.% methyl methacrylate (MMA), 13.9 wt.% methacrylic acid (MAA), and 62.9 wt.% n- butyl methacrylate (nBMA).
  • MMA methyl methacrylate
  • MAA methacrylic acid
  • nBMA n- butyl methacrylate
  • Two different dispersed acrylic copolymers were prepared from emulsifying polymer EP 17, one with GMA and one without GMA, as follows.
  • the solution of emulsifying polymer (55 wt.% non-volatile material) was cooled to 90 °C.
  • DMAE dimethylaminoethanol
  • PG propylene glycol
  • the dispersions were further cooled to 50 °C under stirring whilst bubbling nitrogen through it. The thus-obtained dispersions were approximately water viscous, and all appeared transparent or translucent.
  • the amounts of emulsifying polymer solution, DMAE, PG, and water are given in Table 2 (items 1-4).
  • Ascorbic acid, de-ionized water, further DMAE, and FeSO 4 were then added to the dispersion in the amounts indicated in Table 2 (items 5 to 8).
  • the mixture was held for 15 minutes at 50 °C under stirring whilst bubbling nitrogen through it.
  • the second monomer mixture (items 9 to 11 in Table 2) was then added and stirring was continued for 30 minutes. Further water and a radical polymerization initiator were gradually added (items 12 and 13 in Table 2). The temperature rise due to the exothermal reaction was monitored and the reaction mixture was cooled to room temperature after no exothermal reaction was observed anymore.
  • the second monomer mixture contained 25.0 wt.% methyl methacrylate (MMA), 4.0 wt.% glycidyl methacrylate (GMA), and 71.0 wt.% ethyl acrylate (EA) for the first latex.
  • MMA methyl methacrylate
  • GMA glycidyl methacrylate
  • EA ethyl acrylate
  • the second monomer mixture contained 27.0 wt.% MMA and 73.0 wt.% EA.
  • the second monomer mixture formed 60 wt.% of the solid weight of the final latex.
  • the emulsifying polymer formed 40 wt% of the solid weight of the final latex.
  • Each latex had a nonvolatile material content of 35 wt.% and a VOC (volatile organic content) of 500 g/kg.
  • compositions were prepared from the latex with GMA and from the latex without GMA.
  • the type and amount of crosslinker used in the coating compositions was varied.
  • the coating compositions were prepared as follows. The latex was added to a blending vessel. Dowanol PnB (propylene glycol n-butyl ether) was added in such amounts that the VOC was in the range of from 780 to 1 ,000 g/kg. Finally, a crosslinker and a wax (3 wt.% wax solids on total solids) were added. In Table 5 the type and wt.% of crosslinker (crosslinker solids on resin solids) is given.
  • Dowanol PnB propylene glycol n-butyl ether
  • the coating compositions were applied on acid-washed A4-sized aluminium panels using a wire- wound application bar.
  • the coated panels were then dried in an oven set to 10 seconds bake at a peak metal temperature of 240 °C.
  • the amount of polymer solution applied was such that a film weight of 10-12 grams/m 2 was obtained.
  • Pencil hardness, retort resistance, and enamel rating (ER) of the cured films were determined as described hereinabove. The results of the tests for pencil hardness, enamel rating (ER), and retort resistance are shown in Table 5.
  • a coating composition with acceptable hardness and acceptable flexibility can be obtained both with a phenolic crosslinker and with a p-hydroxy alkyl amide crosslinker and both with a latex with GMA monomer and a latex without a GMA monomer.

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Abstract

L'invention concerne une composition de revêtement aqueuse comprenant un copolymère acrylique dispersé obtenu par polymérisation en émulsion d'un composant monomère à insaturation éthylénique en présence d'une dispersion aqueuse d'un polymère émulsifiant, la dispersion aqueuse du polymère émulsifiant étant obtenue par polymérisation en solution d'un premier mélange de monomères sans styrène contenant de 5 à 20 % en poids d'acide méthacrylique, au moins 15 % en poids de méthacrylate de méthyle, et éventuellement un autre monomère à insaturation éthylénique ; la neutralisation au moins partielle du polymère à fonction acide ainsi obtenu ; et la dispersion du polymère neutralisé dans de l'eau, le composant monomère à insaturation éthylénique étant exempt de styrène et comprenant du méthacrylate de méthyle à hauteur d'au plus 45 % en poids, au moins 47 % en poids d'acrylate d'éthyle et, éventuellement, du méthacrylate de glycidyle, à hauteur d'au plus 8,0 % en poids. L'invention concerne un procédé pour revêtir un boîtier métallique, une partie de celui-ci, ou un substrat métallique pour celui-ci avec une telle composition de revêtement et un article revêtu d'une telle composition de revêtement.
PCT/EP2024/074746 2023-09-12 2024-09-04 Composition de revêtement aqueuse comprenant un copolymère acrylique dispersé Pending WO2025056403A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018013766A1 (fr) 2016-07-15 2018-01-18 Valspar Sourcing, Inc. Composition de revêtement en latex ayant des propriétés de réduction de l'arôme réduites
WO2018085052A1 (fr) 2016-10-19 2018-05-11 Swimc Llc Polymères acryliques et compositions contenant de tels polymères
JP2022016065A (ja) * 2020-07-10 2022-01-21 東洋インキＳｃホールディングス株式会社 食品包装シート用コート剤および食品包装シート
WO2023049779A1 (fr) * 2021-09-22 2023-03-30 Ppg Industries Ohio, Inc. Composition aqueuse de revêtement et emballage revêtu de cette dernière

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018013766A1 (fr) 2016-07-15 2018-01-18 Valspar Sourcing, Inc. Composition de revêtement en latex ayant des propriétés de réduction de l'arôme réduites
WO2018085052A1 (fr) 2016-10-19 2018-05-11 Swimc Llc Polymères acryliques et compositions contenant de tels polymères
US20190249029A1 (en) * 2016-10-19 2019-08-15 Swimc Llc Acrylic polymers and compositions containing such polymers
JP2022016065A (ja) * 2020-07-10 2022-01-21 東洋インキＳｃホールディングス株式会社 食品包装シート用コート剤および食品包装シート
WO2023049779A1 (fr) * 2021-09-22 2023-03-30 Ppg Industries Ohio, Inc. Composition aqueuse de revêtement et emballage revêtu de cette dernière

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Polymer Handbook", 1999, JOHN WILEY & SONS, INC.

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