Environment-friendly aqueous coating composition

Abstract

The present disclosure provides an environmentally friendly aqueous coating composition comprising an aqueous emulsion prepared by emulsion polymerizing at least one radically polymerizable monomer and one or more bifunctional or higher functional chain extending monomers in the presence of an aqueous solution of oligomers, the oligomer is made from a mixture of radically polymerizable monomers comprising an acid functional radically polymerizable comonomer, an adhesion promoting radically polymerizable comonomer, and other radically polymerizable comonomers. The aqueous emulsion is substantially free of adipic dihydrazide, has a minimum film forming temperature of < = 55 DEG C, and has a Koenig hardness when dried of at least 40 seconds.

Description

[0001] This application is a divisional application of the invention patent application filed on February 8, 2018, with application number 201880010835.1 and invention title "Environmentally Friendly Waterborne Coating Composition". Technical Field

[0002] This invention relates to water-based paints and varnishes. Background Technology

[0003] Water-based paints and varnishes are used to coat a wide variety of industrial and consumer goods, including furniture, wood trim, windows, and other objects. When coated surfaces come into contact with each other under pressure, the cured or hardened coating must meet various performance requirements, including adhesion to the substrate, fluid resistance, and anti-blocking properties (adhesion of the coating to itself). Adipate dihydrazide (ADH) is a widely used adhesion promoter and crosslinking agent found in many paints and varnishes. Unfortunately, even when crosslinking enters the coating, ADH is prone to hydrolysis, and hydrolysis byproducts can seep into the surrounding area. In 2014, ADH was classified in Europe as hazardous to the aquatic environment (chronic Group 2) with related hazard description H411 (toxic to aquatic life with long-term effects), see Commission decision (EU) 2016 / 397 of 16 March 2016. However, based on the industry's view that "there is no equally efficient and effective alternative to ADH on the market," the same committee decided to approve the use of ADH in EU eco-label paints and varnishes "where the use of alternative materials is not technically feasible because the coating products cannot provide consumers with the required level of functionality." ADH therefore continues to be used in such paints and varnishes.

[0004] NEOCRYL™ XK-98 is a self-crosslinking acrylic emulsion polymer widely used in many paints and varnishes as an ADH-containing water-based adhesive and is considered similar to the polymer described in European Patent No. EP 0758 364B2. Several suppliers, including Alberdingk Boley and Allnex (formerly NuPlex), now produce similar acrylic emulsion products that are believed to contain ADH. There is a desire to replace these products with ADH-free systems that offer comparable or better performance and have a lower potential for environmental harm.

[0005] Therefore, it should be understood that there is a need in the art for improved ADH-free acrylic emulsion polymers and water-based paint and varnish systems. Such systems are disclosed and claimed herein. Invention Overview

[0006] In one aspect, the present invention provides a method for preparing an aqueous emulsion, the method comprising:

[0007] a) Oligopolymerizing a mixture of radically polymerizable monomers in an aqueous solution, the mixture comprising 1 to 45 wt% of an acid-functional radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5 to 50 wt% of other (i.e., non-acid-functional and non-adhesion-promoting) radically polymerizable comonomers to form a water-soluble oligomer with a number-average molecular weight (Mn) of 500 to 50,000 and a glass transition temperature (Tg) of at least 70°C; wherein the acid-functional comonomer makes the oligomer water-soluble either by means of its own solution or by means of neutralization, and the adhesion-promoting comonomer imparts improved adhesion to the substrate when the coating composition containing the aqueous emulsion is applied to and dried on a wood, plastic, metal, or cement substrate.

[0008] b) In the presence of an aqueous solution of the oligomer, at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an emulsion of 0.1 to 20% by weight of the radically polymerizable monomer to form an aqueous emulsion of a hydrophobic polymer with a Tg at least 40°C lower than that of the oligomer, wherein the weight of the oligomer is 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic dihydrazide, has a minimum film-forming temperature (MFFT) ≤55°C and a Koenig hardness of at least 40 seconds upon drying.

[0009] In some embodiments, the aforementioned bifunctional or higher-functional chain extender monomers may be used as intramolecular crosslinking monomers. For the sake of brevity, these monomers will be referred to as chain extender monomers, regardless of one or more specific roles they may play in forming a particular aqueous emulsion.

[0010] In another aspect, the present invention provides a coating composition comprising an aqueous emulsion of a hydrophobic polymer, said hydrophobic polymer being made from at least one radically polymerizable monomer and at least one bifunctional or higher functional chain-extending monomer in an amount of 0.1 to 20 wt% based on the weight of said radically polymerizable monomer, said hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer, said oligomer being made in the aqueous solution from a mixture of radically polymerizable monomers, said mixture comprising 1 to 45 wt% of an acid-functionalized radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5 to 50 wt% of other radically polymerizable comonomers; said acid-functionalized... The oligomer is a copolymerizable monomer that makes the oligomer water-soluble either by means of its own composition or by means of neutralization, and the adhesion-enhancing copolymer imparts improved adhesion to the substrate when the coating composition is applied to and dried on a wood, plastic, metal, or cement substrate; the oligomer has an Mn of 500-50000 and a Tg of at least 70°C, and the hydrophobic polymer has a Tg at least 40°C lower than that of the oligomer, wherein the weight of the oligomer accounts for 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C, and a Koenig hardness of at least 40 seconds upon drying.

[0011] In another aspect, the present invention provides a coated article comprising a substrate (e.g., wood, plastic, metal, or cement substrate) having layers of a coating composition thereon, the coating composition layers comprising an aqueous emulsion of a hydrophobic polymer, the hydrophobic polymer being made from at least one radically polymerizable monomer and one or more bifunctional or higher functional chain-extending monomers based on 0.1 to 20 wt% of the radically polymerizable monomer, the hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer made from a mixture of radically polymerizable monomers in the aqueous solution, the mixture comprising 1 to 45 wt% of an acid-functional radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 9 8.5-50% by weight of other free radical polymerizable comonomers; the acid-functionalized comonomers make the oligomers water-soluble either by means of neutralization or by means of neutralization, and the adhesion-promoting comonomers impart improved adhesion to the substrate when the coating composition is dried; the number-average molecular weight (Mn) of the oligomers is 500-50000, the glass transition temperature (Tg) is at least 70°C, and the Tg of the hydrophobic polymer is at least 40°C lower than that of the oligomers, wherein the weight of the oligomers accounts for 5 to 50% by weight of the oligomers plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has an MFFT ≤ 55°C, and a Koenig hardness of at least 40 seconds upon drying. Attached Figure Description

[0012] In the attached diagram:

[0013] Figure 1 The image shows a wood panel with a clearcoat being evaluated in a simulated outdoor weathering tester; and

[0014] Figure 2 The image shows stained wooden planks that have been stored outdoors for more than two winters. Invention Details

[0015] The following detailed description illustrates certain embodiments and should not be considered limiting. Unless otherwise specified, all weights, quantities, and proportions herein are by weight. The terms used below have the following meanings:

[0016] A description of a numerical range using endpoints includes all numbers contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0017] The terms “a,” “the,” “at least one,” and “one or more” are used interchangeably. Thus, for example, a coating composition containing “a” additive means that the coating composition contains “one or more” additives.

[0018] The term "acrylic monomers" includes monomers containing acrylic acid or methacrylic acid or that can be derived from acrylic acid or methacrylic acid.

[0019] The term "binder" refers to a natural or synthetic polymer suitable for use in paints and other coating compositions to form a dry, cured, or hardened coating (where the binder may represent a continuous phase).

[0020] The term "carrier" refers to a volatile aqueous or organic liquid solvent or dispersant that can be used to prepare paints and other coating compositions containing suspended pigments and other suspended solid particulate materials.

[0021] When used in relation to monomers capable of free radical polymerization, the term "comonomer" refers to a monomer that undergoes free radical copolymerization with one or more other free radical polymerizable monomers in the presence of suitable reaction conditions (including, if necessary, a suitable initiator).

[0022] The term "bifunctional or higher functional chain extender monomer" refers to a monomer having at least two sites (e.g., vinyl, vinyl ether, olefinic unsaturated sites, allyl, or combinations thereof) that can react during free radical polymerization to extend the growing polymer chain or bridge two growing polymer chains.

[0023] When used in adhesives, the term "film formation" refers to the application of a solution or dispersion of the adhesive as a thin wet layer (e.g., about 150-200 μm thick) onto a suitable support, and drying, curing, or otherwise hardening (if necessary, with the aid of a suitable coalescing agent) to form a substantially continuous dry film coating (e.g., about 75-100 μm thick) containing the polymer on the support.

[0024] When used in relation to water-based particulate polymers, the term "emulsion polymer" refers to a polymer that is not typically dispersed in water on its own; rather, emulsion polymers require the presence of a secondary emulsifier (e.g., the aforementioned oligomers or surfactants present during emulsion polymerization) to produce an emulsion of polymer particles in water.

[0025] When used with respect to monomers or comonomers, the term "radical polymerizable" refers to a monomer or comonomer that undergoes radical polymerization with one or more other such radical polymerizable monomers in the presence of suitable reaction conditions (including, if necessary, a suitable initiator). Exemplary radical polymerizable monomers and comonomers may, for example, contain one or more vinyl, vinyl ether, olefinic unsaturated sites, allyl, etc.

[0026] When used in colorants, paints, and other coating compositions, the term "low VOC" means that the colorant or coating composition contains less than about 50 g / L of volatile organic compounds. VOC levels can be measured using ASTM D6886-14 with methyl palmitate as the boiling point label.

[0027] The term "(meth)acrylic acid" includes one or both of acrylic acid and methacrylic acid, and the term "(meth)acrylate" includes one or both of acrylate and methacrylate. Similar usage is used for other derivatives of acrylic acid and methacrylic acid, such as (meth)acrylamide, (meth)acrylaldehyde, etc.

[0028] The term “monomer” refers to a reactive organic molecule that can be covalently bonded to other molecules or to itself to form an oligomer or polymer containing multiple units (e.g., multiple repeating units) derived from the monomer.

[0029] The term "oligomer" refers to a molecule with an intermediate relative molecular mass whose structure essentially comprises multiple units that are actually or conceptually derived from molecules with a lower relative molecular mass.

[0030] The term "polymer" (polymer and polymeric) refers to a molecule with a high relative molecular mass whose structure essentially consists of multiple repeating units that are actually or conceptually derived from molecules with a low relative molecular mass.

[0031] The terms "preferred" and "ideally" refer to embodiments of the invention that may provide certain benefits in certain circumstances. However, other embodiments may also be preferred in the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are useless, and is not intended to exclude other embodiments from the scope of the invention.

[0032] When used in relation to aqueous emulsions or coating compositions, the term "solvent-based" means that the primary liquid carrier or support used in such aqueous emulsions or coating compositions is a non-aqueous solvent or a mixture of non-aqueous solvents.

[0033] When used relative to components that may be found in an aqueous emulsion or coating composition, the term "substantially free" means that the aqueous emulsion or coating composition contains less than about 5% by weight of that component based on the total weight of the composition.

[0034] When used in relation to an organic group, the term "vinyl" refers to a segment having the formula -CH=CH2-.

[0035] When used in relation to an aqueous emulsion or coating composition, the term "water-based" means that the primary volatile liquid carrier or support used in such an aqueous emulsion or coating composition is water.

[0036] When used in relation to an oligomer or polymer, the term "water-dispersible" means that the oligomer or polymer can be dispersed in water without the use of a separate surfactant or water, and that an external acid or base may be added to the oligomer or polymer if desired to form a stable dispersion at normal storage temperatures. Water-dispersible oligomers or polymers may contain nonionic or anionic functional groups on the oligomer or polymer to facilitate its water dispersibility. For such oligomers or polymers, this dispersion typically requires an external acid or base; however, these are not considered secondary emulsifiers (e.g., surfactants) used, for example, to disperse water-insoluble latex polymers in water.

[0037] Various acid-functional free radical polymerizable comonomers can be used to prepare the disclosed water-soluble oligomers. The acid-functional comonomers make the oligomers at least partially water-soluble in the aqueous solution in which the oligomerization reaction takes place. This means that the oligomers are either completely dissolved in the aqueous solution, or substantially completely dissolved, so that they exist as a true (i.e., clear) solution, or some oligomers are dispersed in the aqueous medium while others are dissolved therein. This water solubility is either inherent or achieved through neutralization. Therefore, the acid-functional oligomers contain a sufficient concentration of acidic groups to make the oligomers partially or more preferably completely soluble in the aqueous medium, if desired, by neutralizing the acidic groups, for example, by adjusting the pH of the aqueous medium. Typically, the medium in which the oligomers are located (usually the aqueous polymerization medium in which the oligomers have been prepared) will be acidic, with a pH < 7. Moreover, the acidic groups are typically carboxyl groups. In this case, if dissolution does not occur, the neutralization of the acidic groups can be accomplished by increasing the pH of the medium. This is typically accomplished by adding a base, such as an organic or inorganic base, examples of which include organic amines, such as trialkylamines (e.g., triethylamine and tributylamine), morpholine and alkanolamines, and inorganic bases, such as ammonia, NaOH, KOH, and LiOH. In some embodiments, the aqueous medium containing the acid-functional oligomer may already be alkaline or sufficiently alkaline, such that the acidic groups (e.g., carboxyl groups) are neutralized without the need to add a base to raise the pH. In some embodiments, the acidic groups may be, or may include, very strong acidic groups, such as sulfonic acid groups (having, for example, a pKa of 1 to 2), for which neutralization may not be necessary to achieve dissolution. In some embodiments, the acid-functional free radical polymerizable comonomer may be polymerized in salt form rather than as a free acid. The acid functional group may be present in the acid-functional comonomer as provided, or may be an acid-forming group (e.g., anhydride, such as methacrylic anhydride or maleic anhydride, or acyl chloride) that generates or is subsequently convertible into an acidic group.

[0038] Typically, acid-functionalized radical-polymerizable comonomers will contain one or more acidic sites and one or more radical-polymerizable sites. Exemplary acid-functionalized radical-polymerizable comonomers include acrylic acid monomers and other olefinically unsaturated carboxyl-containing monomers, such as acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. Sulfonic acid-containing monomers, such as styrene-p-sulfonic acid (or the corresponding styrene-p-sulfonyl chloride), can also be used. Acid-functionalized radical-polymerizable comonomers can be polymerized as salts or as free acids, such as NH4+ of ethyl methacrylate-2-sulfonic acid or 2-acrylamido-2-methylpropanesulfonic acid. + Either alkali metal salts, or their corresponding free acids.

[0039] The disclosed water-soluble oligomers can be prepared using various adhesion-promoting olefinic unsaturated comonomers. Exemplary such comonomers typically contain one or more (usually one) groups with affinity for the desired substrate and one or more (usually one) sites for radical polymerization. The substrate-affinity group can be, for example, a polar group, such as an aldehyde, ketone, ester, hydroxyl, silyl, urea group, or other groups that impart improved adhesion to the substrate when a coating composition containing an aqueous emulsion is applied to and dried on the desired substrate (e.g., a wood substrate). Carboxylic acid groups can also promote adhesion, but the acid groups discussed above in relation to acid-functionalized radical-polymerizable comonomers can additionally be used to make the oligomer itself water-soluble or to make the oligomer water-soluble by neutralization. Therefore, adhesion-promoting olefinic unsaturated comonomers may contain carboxylic acid groups, but ideally also contain one or more other groups with affinity for the desired substrate.

[0040] Exemplary adhesion-promoting olefinic unsaturated comonomers include hydroxyalkyl groups (e.g., C1-C12). 12Acetyl acetylacetyl esters of (meth)acrylates, such as acetylacetyl methacrylate (“AAEM”, CAS No. 21282-97-3); unsaturated ketones, such as acrolein (CAS No. 107-02-8), methacrolein (CAS No. 78-85-3), and vinyl methyl ketone (“MVK” or butenone, CAS No. 107-02-8). No. 78-94-4); hydroxyalkyl (meth)acrylates, such as 2-hydroxymethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 5,6-dihydroxyhexyl methacrylate and cyclotrimethylolpropane methyl acetal acrylate (also known as (5-ethyl-1,3-dioxane-5-yl) methyl acrylate, CAS No. 66492-51-1); ketone-containing amides, such as diacetone acrylamide (“DAAM”, CAS No. 2873-97-4); tetrahydrofurfuryl acrylate (CAS No. 2399-48-6); urea methacrylate (CAS No. 78-94-4); No. 86261-90-7 (sometimes provided as a 25% solution in methyl methacrylate); vinyl silane; other monomers familiar to those skilled in the art based on this description. DAAM is a particularly preferred comonomer for compositions intended for use on bare wood, interior walls, aged alkyd resins, and low surface energy plastics such as polyvinyl chloride (“PVC”). Vinyl silanes such as vinyltrimethoxysilane (CAS No. 2768-02-7) are particularly preferred for compositions intended for use on cementitious substrates such as concrete, cement board, and fiber cement board. When the composition is mixed with or used on top of an oil-based coating such as an alkyd resin, the adhesion-promoting olefinic unsaturated comonomer may also be, or instead be, a free-radical polymerizable monomer substituted with a lipophilic long-chain alkyl group, such as lauryl methacrylate. When the adhesion-promoting olefinic unsaturated comonomer is a ketone-containing monomer such as AAEM or DAAM, the remainder of the disclosed coating composition preferably does not contain ketone reactive components such as ADH. ADH can promote the crosslinking and consumption of ketone groups, thereby reducing the extent to which adhesion-promoting olefinic unsaturated comonomers can impart improved adhesion to the substrate. In another embodiment, after oligomerization and neutralization of acidic functional groups in water (e.g., using ammonia), oligomers prepared using AAEM or DAAM can be converted into soluble oligomers with primary amine adhesion-promoting groups. This conversion can be carried out, for example, by post-adding about 1 equivalent of a diamine (e.g., hydrazine) to an aqueous emulsion.

[0041] Various other (i.e., non-acid-functional and non-adhesion-promoting) olefinic unsaturated comonomers can be copolymerized with acid monomers and adhesion-promoting olefinic unsaturated comonomers. Exemplary examples of such other monomers include acrylates and methacrylates (discussed in more detail below), styrene derivatives (e.g., styrene and various substituted styrene derivatives, such as α-methylstyrene and tert-butylstyrene), nitriles (e.g., acrylonitrile and methacrylonitrile), dienes (e.g., 1,3-butadiene and isoprene), vinyl esters (e.g., vinyl alkylates, such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, and vinyl hexanoate), and free-radical polymerizable vinyl halides (e.g., vinyl chloride, vinylidene chloride, and vinyl fluoride). Exemplary acrylates include C1 to C1... 12 Straight-chain and branched alkyl esters of alcohols and acrylic acid, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, and cycloalkyl acrylates (typically C5-C6). 12 ) esters, such as isobornyl acrylate and cyclohexyl acrylate. Exemplary methacrylates include C1 to C1 esters. 12 Alcohols and straight-chain and branched alkyl esters of methacrylic acid, such as methyl methacrylate, ethyl methacrylate, and n-butyl methacrylate, and cycloalkyl methacrylic acids (typically C5 to C6). 12 Esters, such as isobornyl methacrylate and cyclohexyl methacrylate. Other preferred monomers include methyl methacrylate, styrene, ethyl acrylate, n-butyl acrylate, and n-butyl methacrylate.

[0042] The disclosed mixture of olefinic unsaturated monomers comprises 1 to 45 wt% of an acid-functionalized olefinic unsaturated comonomer, 0.5 to 20 wt% of an adhesion-promoting olefinic unsaturated comonomer, and 98.5-50 wt% of other olefinic unsaturated comonomers. In some embodiments, the disclosed mixture may comprise at least about 2 wt% or at least about 5 wt% to at most about 15 wt% or at most about 10 wt% of an acid-functionalized olefinic unsaturated comonomer. In other embodiments, the disclosed mixture may comprise at least about 1 wt% and at most about 5 wt% of an adhesion-promoting olefinic unsaturated comonomer. In further embodiments, the disclosed mixture may comprise at least about 60 wt%, at least about 70 wt%, or at least about 80 wt% of other other olefinic unsaturated comonomers.

[0043] As described above, the Mn value of the oligomer is between 500 and 50,000. Oligomers with Mn values ​​at the lower limit of this range tend to form transparent solutions. The Mn value of the oligomer should not be so high as to form insoluble particles but rather water-soluble oligomers. In some embodiments, the Mn value of the oligomer is between about 2,500 and about 5,000.

[0044] As described above, the oligomer has a Tg of at least 70°C. The Tg value can be calculated based on the Fox equation, or it can be measured using techniques such as differential scanning calorimetry (“DSC”). The Tg of the oligomer can be selected in part based on the Tg of the hydrophobic polymer to obtain a hydrophobic polymer Tg at least 40°C lower than the oligomer's Tg. Oligomers with too low a Tg can induce adhesion. In some embodiments, the oligomer has a Tg of 70 to 125°C, and in some embodiments, the Tg is at least 80°C or 80 to 125°C. In some embodiments, the oligomer is formed in the form of an aqueous emulsion free of organic solvents, and in some embodiments, the oligomer does not contain functional groups that would impart crosslinkability when the aqueous emulsion is coated onto a substrate and dried.

[0045] The general procedure used in step a) of the aqueous oligomerization reaction is familiar to those skilled in the art and can be performed by dispersing the monomer in an aqueous medium and oligomerizing it with a free radical initiator (preferably a water-soluble initiator) accompanied by heating (e.g., at 5 to 95°C) and stirring or other agitation as needed, to obtain the desired oligomer reaction rate and yield. Higher temperatures can be applied by pressurizing the reaction vessel. Lower temperatures can be assisted by using a suitable initiator or reducing agent (e.g., sodium dithionate). Typically, one or more conventional emulsifiers (i.e., surfactants) are used in the oligomerization reaction, such as anionic or nonionic emulsifiers, such as sodium, potassium, or ammonium salts of dialkyl sulfosuccinic acid, sodium, potassium, or ammonium salts of sulfated oil, sodium, potassium, or ammonium salts of alkyl sulfonic acid, sodium, potassium, or ammonium salts of alkyl sulfate (e.g., sodium dodecyl sulfate), or sodium, potassium, or ammonium salts of fatty acids (e.g., sodium stearate and sodium oleate); alkali metal salts of sulfonic acids, C 12-24Fatty alcohols, ethoxylated fatty acids, or fatty amides; aryl analogs of the above-mentioned alkyl-containing emulsifiers; and phosphates. A low emulsifier dosage is preferred, for example, 0.3 to 2% by weight or 0.3 to 1% by weight of the emulsifier based on the total monomers added to the reaction vessel. The oligomerization reaction can use one or more conventional free radical initiators. Exemplary initiators include peroxides, such as hydrogen peroxide, tert-butyl hydroperoxide, and cumene hydroperoxide; persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate; and redox initiator systems, such as combinations of tert-butyl hydroperoxide, isoascorbic acid, and ferric sodium ethylenediaminetetraacetate (FeEDTA). The amount of initiator or initiator system can be, for example, about 0.05 to 3% based on the total monomers added. Oligopolymerization can be carried out using an "integrated" batch addition process (i.e., all components to be used are present at the start of the oligopolymerization reaction), a semi-batch process (i.e., one or more components, typically at least one monomer, are added to the reaction vessel, either wholly or partially, during the oligopolymerization reaction), or a continuous process (i.e., components are added to the reaction vessel continuously during the oligopolymerization reaction). It is desirable to control the molecular weight of the oligomer by using suitable chain transfer agents such as thiols (mercaptan or thiol), halogenated hydrocarbons, or α-methylstyrene. If the oligomer formed in step a) is not water-soluble, it is preferable to neutralize it before or at the start of the polymerization reaction in step b).

[0046] In step b), various free radical polymerizable monomers can be used to form a hydrophobic polymer. Exemplary such monomers include other (i.e., non-acid functional and non-adhesion-promoting) olefinic unsaturated comonomers described above with respect to oligomerization reactions, and other free radical polymerizable monomers such as o-methylstyrene, m-methylstyrene, and p-methylstyrene; o-ethylstyrene, m-ethylstyrene, and p-ethylstyrene; p-chlorostyrene and p-bromostyrene; alkanols (typically C1-C1). 12 Straight-chain and branched acrylates and methacrylates, such as tert-butyl methacrylate and 2-ethylhexyl methacrylate; and dienes such as 1,3-butadiene and isoprene. The type and amount of these other monomers are preferably selected to provide a hydrophobic polymer having a Tg at least 40°C lower than that of the oligomer. Sufficient free-radical polymerizable monomers are preferably used to provide at least about 50% by weight, at least about 55% by weight, or at least about 60% by weight and at most about 95% by weight, at most about 90% by weight, or at most about 80% by weight of the hydrophobic polymer as a percentage of the combined weight of the oligomer and the hydrophobic polymer.

[0047] Hydrophobic polymers can be formed using a variety of bifunctional or higher-functional chain extenders. Exemplary such chain extenders include bifunctional or higher-functional acrylates or methacrylates, such as 1,3-butanediol diacrylate, 1,4-butanediol diacrylate (“BDDA”), 1,6-hexanediol diacrylate (“HDDA”, CAS No. 13048-33-4), and ethylene glycol dimethacrylate (“EGDMA”, CAS No. 97-90-5); allyl acrylates and methacrylates, such as allyl methacrylate (“AMA”, CAS No. 96-05-09); vinylsilanes, such as vinyltrimethoxysilane (CAS No. 2768-02-7); and hydroxyalkyl groups (e.g., C1-C1). 12 Acetylacetoxy esters of (meth)acrylates, such as AAEM. Bifunctional chain extenders represent a preferred subclass of such monomers. The type and amount of chain extenders are desirablely selected to provide a hydrophobic polymer with a Tg at least 40°C lower than that of the oligomer. In some embodiments, the hydrophobic polymer is formed from at least about 0.1 wt%, at least about 0.25 wt%, or at least about 0.5 wt% of the chain extender. In other embodiments, the hydrophobic polymer is formed from at most about 3 wt%, at most about 2 wt%, or at most about 1.5 wt% of the chain extender.

[0048] Step b) The general procedure used in the emulsion polymerization reaction is familiar to those skilled in the art and can be carried out by dispersing the monomers in an aqueous medium containing oligomers and one or more suitable free radical initiators. Various reaction schemes can be used to combine the reactants, the following being exemplary. In one embodiment, an aqueous solution of the oligomers is mixed with all the monomers used to form the hydrophobic polymer, and a conventional “integrated” batch polymerization is performed without further addition of monomers to produce the polymer. In another embodiment, the polymerization is still essentially a batch process, wherein all the oligomer solution is present in the polymerization vessel along with some of the monomer system for the hydrophobic polymer before polymerization begins, and the remaining portion of the monomer system is rapidly added in a single addition at appropriate times after polymerization begins. In yet another embodiment, the polymerization is still essentially a batch process, wherein all the oligomer solution is present in the polymerization vessel before polymerization begins, but the monomer system for the hydrophobic polymer is divided into several equal portions. These portions are added sequentially to each other and polymerized to gain more control over the polymerization, effectively providing a polybatch process.

[0049] In other embodiments, a semi-batch process is employed, wherein a portion (or none) of the monomer system for the hydrophobic polymer is present in the polymerization reactor prior to polymerization, and is partially (or entirely) added to the polymerization reactor during polymerization. In one such embodiment, an aqueous oligomer solution is (partially) present in the reaction medium for polymerization, while a portion of the aqueous oligomer solution, acting as an emulsifier, is mixed with the entire monomer system for the hydrophobic polymer and then fed into the polymerization reactor during polymerization. In another embodiment, the entire oligomer solution is present in the reaction reactor prior to polymerization, and the entire monomer system for the hydrophobic polymer is added to the reactor during polymerization, i.e., no oligomers are present in the monomer feed. In yet another embodiment, all the aqueous oligomer solution is present in the reaction reactor along with a portion of the monomer system for the hydrophobic polymer prior to polymerization, and the remainder of the monomer system is fed during polymerization (i.e., no oligomers are present in the feed). In another embodiment, a portion of the oligomer solution is present in the reaction vessel along with a portion of the monomer system for the hydrophobic polymer prior to the start of polymerization, and the remainder of the monomer system, mixed with the remaining portion of the oligomer solution, is fed during polymerization.

[0050] In the various reaction schemes described above, it is preferable to omit most or all of the individual emulsifiers and instead rely entirely or partially on water-soluble oligomers to emulsify the polymer formed in step b). Unbound by theory, oligomers can stabilize hydrophobic polymers during polymer formation, where the polymerization reaction of the hydrophobic polymer forms insoluble, rubbery, hydrophobic polymer particles surrounded by oligomers, which act as surfactants to disperse or assist in dispersing the hydrophobic polymer particles in the aqueous emulsion. Therefore, the aqueous emulsion obtained from step b) preferably contains very low levels of added emulsifiers (excluding the oligomers themselves), for example, less than 0.5% or less than 0.25% based on the total weight of the added monomers, or no such added emulsifiers, and the only emulsifier present (excluding the oligomers themselves) is preferably a remnant from the oligomerization reaction in step a).

[0051] In a preferred embodiment, the disclosed hydrophobic polymer preferably comprises a rubbery high molecular weight material that has been chain-extended in step b), is prepared without the addition of a crosslinking agent (e.g., without the addition of a hydrolyzable crosslinking agent), and provides a polymeric adhesive polymer that is coalescing rather than self-crosslinking. The polymer may, for example, have an MFFT of about 0 to about 55°C (e.g., about 0 to about 30°C) and a Koenig hardness of at least about 40 seconds (e.g., about 60 to about 200 seconds). The polymer may, for example, have an elongation of about 100 to about 240%, a non-stick surface, and an anti-blocking property of 4 or 5 in the anti-blocking test shown below. The flexibility, elongation, and anti-blocking properties of the polymer product may be influenced in part by the respective Tg values ​​of the oligomer and the hydrophobic polymer, and by the differences between these Tg values. For example, if the oligomer Tg is below about 80°C, the anti-blocking properties of the hydrophobic polymer may be adversely affected. If the hydrophobic polymer Tg is greater than about -20°C, the polymer may have reduced flexibility. In some embodiments, the hydrophobic polymer has a Tg of less than about -40°C or less than about -60°C.

[0052] The performance characteristics of the product polymer can also be affected by the relative amounts of oligomers and hydrophobic polymers, as well as the amount of chain extender monomers. For example, as the amount of hydrophobic polymers increases relative to the amount of oligomers, water resistance may increase. In some embodiments, the oligomers account for about 1 to about 70% by weight, or about 5 to about 50% by weight, of the total solids of the oligomers and hydrophobic polymers. Moreover, when the amount of chain extender monomers increases beyond about 1.5% by weight, the flexibility of the film may decrease. By appropriately adjusting the above factors, a product polymer with a desired balance of factors, including anti-blocking properties, water resistance, and elasticity, can be obtained.

[0053] The aforementioned NEOCRYLXK-98 self-crosslinking acrylic emulsion polymer is believed to be prepared by adding an ADH crosslinking agent at the end of polymerization, as mentioned in the aforementioned European patent EP 0 758 364 B2 as step c). The hydrophobic polymer disclosed in this invention is preferably prepared without such step c), i.e., without adding a crosslinking agent at the end of polymerization. Omitting the crosslinking agent also eliminates undesirable discharge of crosslinking agents into drains, water treatment systems, and water bodies when used brushes, rollers, or containers are washed to remove excess coating composition. Omitting the crosslinking agent after coating and curing the coating composition can also provide beneficial effects. For example, ADH is a relatively readily hydrolyzable Schiff base, and its hydrolysis reaction can be catalyzed by acids and bases, including acid rain and concrete or other alkaline substrates. The hydrolysis reaction releases ADH from the crosslinked coating. Therefore, ADH and other hydrolyzable crosslinking agents are preferably not used in the disclosed coating compositions. Other exemplary hydrolyzable crosslinking agents include other polyhydrazides (e.g., oxalate dihydrazides, succinate dihydrazides, caprylate dihydrazides, and phthalate dihydrazides), polyisocyanates, melamine, glycourea, polyamines (e.g., isophorone diamine and 4,7-dioxane-1,10-diamine), and diacids such as terephthalic acid. It is also desirable to avoid crosslinking agents that may release volatile diacrylates with potentially unpleasant odors. Therefore, the disclosed coating compositions are preferably free of or substantially free of added crosslinking agents, particularly hydrolyzable or odor-producing crosslinking agents. In one exemplary embodiment, the disclosed coating composition contains less than 0.01% of a free hydrolyzable or odor-producing crosslinking agent, such as less than 0.01% of free ADH.

[0054] Compared to the aforementioned NEOCRYLXK-98 polymer, the currently disclosed polymer preferably also has an increased oligomer molecular weight, uses monomers with lower Tg to prepare the polymer, and produces a more rubbery polymer.

[0055] If desired, one or more crosslinking functional monomers may optionally be added to the disclosed coating composition. Such added functional monomers are typically not acid-functional monomers. Exemplary examples of such added monomers include hydroxyl or epoxy-functionalized (meth)acrylates, such as hydroxyalkyl (typically C1-C4) 12 ) Methacrylates, such as 2-hydroxyethyl methacrylate, glycidyl methacrylate and their corresponding acrylates; ketone and aldehyde functionalized monomers, such as acrolein, methacrolein and methyl vinyl ketone; hydroxyalkyl groups (usually C1-C1) 12Acetyl acetylacetyl esters of acrylates and methacrylates, such as acetylacetyl acrylate or acetylacetyl methacrylate; and ketone- or aldehyde-containing amides, such as diacetone acrylamide. Small amounts (e.g., less than 5% by weight, preferably less than 2% by weight) of one or more acid-functionalized monomers (e.g., acrylic acid or methacrylic acid) may also be used to form hydrophobic polymers, provided that their inclusion does not unduly and adversely affect the hydrophobic properties of the resulting polymer. In a preferred embodiment of the hydrophobic polymer, acid-functionalized monomers (other than monomers used to prepare oligomers) are not used in the formation of the hydrophobic polymer. In one embodiment, the hydrophobic polymer uses methacrylic acid C... 1-10 Alkyl esters (such as n-butyl methacrylate), C-acrylate 3-10 Prepared from at least one of alkyl esters such as n-butyl acrylate, and typically diacetone acrylamide and / or acetyl acetoxyethyl methacrylate.

[0056] The disclosed coating compositions preferably exhibit good in-tank stability, low content of leachable materials (e.g., low content of leachable oligomers), low chalking, and low whitening. The disclosed coating compositions may be solvent-free or may contain small amounts (e.g., up to about 5% by weight of a low-VOC solvent, such as a coalescing solvent). The cured or hardened coating may be transparent, translucent, or colored. Representative pigments are familiar to those skilled in the art and are described, for example, in U.S. Patent Nos. 8,141,599B2 (Korenkiewicz et al.) and 9,284,467B2 (Booth et al.). The disclosed coating compositions may include a variety of other additives, including anti-cratering agents, biocides, colorants, crosslinking agents, curing indicators, defoamers, dyes, fillers, matting agents, flow control agents, fungicides, heat stabilizers, leveling agents, abrasion and wear additives, plasticizers, rheology control agents, sedimentation inhibitors, surfactants, thickeners, UV absorbers, waxes, etc. The solid content of the final coating composition may be, for example, at least about 20% or at least about 30% by weight, and at most about 65% or at most about 55% by weight, based on the total weight. If necessary, the solid content may be adjusted by adding water or removing water (e.g., by distillation or ultrafiltration).

[0057] The disclosed coating compositions can be used in a variety of products, including interior and exterior coatings (e.g., gloss, semi-gloss, satin, eggshell, or flat paints), glazes, lazure finishes, and pigments (e.g., clear, translucent, or opaque penetrating or non-penetrating pigments). The disclosed coating compositions can be applied to a wide range of substrates, including rolls and other forms of sheet metal, cans, fabrics, vinyl and other plastics, paper, plaster, plaster wall panels, cement fiberboard, concrete, sheet metal, wire, metal parts, wood, wood veneer, etc. Selected substrates may include, for example, walls, ceilings, floors, decorations, siding, decks, roofs, furniture, etc. The coating compositions can be applied to the substrates using any suitable coating method. For example, the compositions can be applied using an air knife system via roller coating, spraying, curtain coating, vacuum coating, brushing, or floodcoating. Preferred coating methods provide uniform coating thickness and are cost-effective. Particularly preferred coating methods employ factory equipment that moves the substrate through the coating head and then through suitable drying or curing equipment. The coated composition can be dried naturally at ambient temperature, or the drying process can be accelerated by heating.

[0058] Exemplary end uses of the coating include coatings for agricultural implements, building equipment, exterior finishes for automobiles, trucks, or aircraft, appliance coatings, furniture coatings, overprint varnishes, inks, adhesives, floor finishes, etc. The recommended thickness of the dried or hardened coating composition is about 10 to about 200 micrometers, preferably about 25 to about 120 micrometers, more preferably about 30 to about 100 micrometers, and most preferably about 35 to about 75 micrometers.

[0059] Various tests can be used to evaluate the disclosed compositions, including those discussed below.

[0060] ISO 2812-4:2007 - Determination of resistance to liquids

[0061] The coating composition was applied as a 100-micron-thick wet film onto black Leneta cardboard (Leneta Company) coated with plastic and dried for 7 days at ambient temperature and humidity. A water spot was applied and left on top of the coating for 24 hours. After removing the water, the degree of coating damage was assessed using a 5-point rating scale, where "5" corresponds to an unaffected coating, "0" corresponds to a completely destroyed coating, and ratings from "1" to "4" represent progressively increasing levels of improvement.

[0062] ISO 1522:2006 - Pendulum damping test (Koenig hardness)

[0063] The coating composition was applied as a 90 μm thick wet film coating onto a glass plate and allowed to dry for 7 days at ambient temperature and humidity. The test pendulum was released, and the number of seconds required for the pendulum to stop was recorded.

[0064] ASTM D2370 - Standard Test Method for Tensile Properties of Organic Coatings

[0065] 3g of the solvent-free portion of the polymer dispersion was coated onto a 10cm diameter polyethylene cap and allowed to dry at ambient temperature and humidity for 7 days. The dried film samples were evaluated using a tensile testing machine, and the elongation at break was recorded.

[0066] Resistance to thermal adhesion (modified version of ASTM D4946)

[0067] The coating composition was applied to a pine substrate in three consecutive coats as 6cm × 2cm stripes. Each coat used 10mg / m². 2 The coating weight, with a 4-hour room temperature (i.e., 23°C) drying time after the first and second coatings, and a 16-hour room temperature drying time after the third coating. Two coated pine substrates are pressed together face-to-face, with their stripes facing each other, using 1 kg / cm² at room temperature. 2 Apply pressure for 4 hours. Pull the coated substrate apart and assess the damage visually and audibly. Use a 5-point rating scale to evaluate the degree of visual coating damage, where "5" corresponds to an unaffected coating, "0" corresponds to a completely destroyed coating, and "1" to "4" indicate increased improvement.

[0068] The invention is further described in the following embodiments, wherein all parts and percentages are by weight unless otherwise stated.

[0069] abbreviation

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] Example 1

[0077] Preparation of oligomer 1

[0078] A high Tg oligomer composed of UMA / MAA / MMA in a 6 / 8 / 86 ratio was prepared by combining the components shown in Table 1 below. 100 parts water and 0.5 parts 25% SDS solution were added to a reaction vessel and heated to 80°C. A preemulsion was prepared from components 3-9, and a premix from components 10-11. 5% of the preemulsion was added to the reaction vessel, followed by 30% of the premix. The reaction vessel was allowed to drift to 85°C. The remaining preemulsion and premix were then fed into the reaction vessel in parallel, with the preemulsion added over a 60-minute time span and the premix over a 70-minute time span. After adding the premix, the reaction vessel was held at 85°C for 30 minutes. Another premix prepared from components 12-13 was added to the reaction vessel to neutralize the oligomer solution to pH 8.25. The reaction mixture was stirred at 85°C for 30 minutes and then cooled to room temperature. The resulting oligomer solution contained 27.5% solids and had a viscosity of less than 250 mPa·s. The oligomer had an Mn value of 2957, a weight-average molecular weight (Mw) of 11061, and a Tg of 110℃.

[0079] Table 1

[0080]

[0081]

[0082] Example 2

[0083] Preparation of oligomer 2

[0084] Using the method of Example 1, oligomers with low Tg were prepared using UMA / MAA / MMA / EA in a ratio of 6 / 6 / 76 / 12 and with 0.32 parts nDM and 0.16 parts 3-MPA. The resulting oligomer solution contained 27.5% solids and had a viscosity of less than 250 mPa·sc. The oligomer had an Mn value of 2427, a Mw value of 5847, and a Tg of 76°C.

[0085] Example 3

[0086] Preparation of oligomer 3

[0087] Using the method of Example 1, high Tg oligomers were prepared using MAA / MMA at a ratio of 6 / 94, without the use of adhesion-promoting comonomers. The resulting oligomer solution contained 27.5% solids and had a viscosity of less than 250 mPa·s. The oligomer had an Mn value of 4100, a Mw value of 13352, and a Tg of 110°C.

[0088] Example 4

[0089] Preparation of oligomer 4

[0090] Using the method of Example 1, high Tg oligomers were prepared using DAAM / MAA / MMA in a ratio of 6 / 8 / 86. The resulting oligomer solution contained 27.5% solids and had a viscosity of less than 250 mPa·sc. The oligomer had an Mn value of 2988, a Mw value of 11184, and a Tg of 110°C.

[0091] Example 5

[0092] Preparation of oligomer 5

[0093] Using the method of Example 1, high Tg oligomers were prepared using VTMeOSi / MAA / MMA in a 6 / 8 / 86 ratio and with 1 part SDS solution. The resulting oligomer solution contained 27.5% solids and had a viscosity of less than 250 mPa·s. The oligomer had an Mn value of 3742, a Mw value of 11763, and a Tg of 110°C.

[0094] Example 6

[0095] Preparation of hydrophobic polymer 1

[0096] A hydrophobic polymer was prepared using the components shown in Table 2 below, employing a rigid high-Tg oligomer (oligomer 1) and a soft polymer prepared by polymerizing BA / BMA / MMA / UMA / BDDA in a 70 / 12 / 16 / 1 / 1 ratio in the presence of oligomer 1. 100 parts water and 141.8 parts oligomer 1 were added to a reaction vessel and heated to 35°C. A monomer premix prepared from components 3-7 was added in half to the reaction vessel and mixed for 30 minutes. A first initiator premix prepared from components 8 and 9 was added to the reaction vessel. A second initiator premix prepared from components 10 and 11 was added in half to the reaction vessel at once. A third initiator premix prepared from components 12 and 13 was added in one-sixth of the mixture at once. The reaction mixture was heated to 55°C. After 10 minutes, the remaining one-third of the third initiator premix was added to the reaction vessel over a 30-minute period. The reaction mixture was cooled to 40°C. The remaining half of the monomer premix was added to the reaction vessel, then mixed and the remaining second and third premix solutions as described above were added. The reaction mixture was cooled to room temperature. The performance characteristics of the resulting aqueous emulsion are shown in Table 3 below:

[0097] Table 2

[0098]

[0099]

[0100] Table 3

[0101]

[0102] Example 7

[0103] Preparation of hydrophobic polymer 2

[0104] Using the method of Example 6, a hydrophobic polymer was prepared by polymerizing a soft, low-Tg oligomer (oligomer 2) and a soft polymer prepared by polymerizing BA / BMA / MMA / UMA / BDDA in a 62 / 23 / 13 / 1 / 1 ratio in the presence of oligomer 2. The performance characteristics of the resulting aqueous emulsion are shown in Table 4 below:

[0105] Table 4

[0106]

[0107]

[0108] Example 8

[0109] Preparation of hydrophobic polymer 3

[0110] Using the method of Example 6, a hydrophobic polymer was prepared by polymerizing a rigid oligomer (oligomer 3) and a soft polymer prepared by polymerizing BA / BMA / MMA in a 71 / 13 / 16 ratio in the presence of oligomer 3. The performance characteristics of the resulting aqueous emulsion are shown in Table 5 below:

[0111] Table 5

[0112]

[0113] Example 9

[0114] Preparation of hydrophobic polymer 4

[0115] Hydrophobic polymers were prepared using the method of Example 6, employing a rigid, high-Tg oligomer (oligomer 4) and a soft polymer prepared in the presence of oligomer 4 using diacetone acrylamide as an adhesion-promoting olefinic unsaturated comonomer and BA / BMA / MMA / DAAM in a ratio of 71 / 12 / 16 / 1. The performance characteristics of the resulting aqueous emulsions are shown in Table 6 below.

[0116] Table 6

[0117]

[0118]

[0119] Example 10

[0120] Preparation of hydrophobic polymer 5

[0121] Using the method of Example 6, a hydrophobic polymer was prepared by polymerizing a rigid oligomer (oligomer 5) and a soft polymer prepared by polymerizing BA / BMA / MMA / UMA / BDDA in a ratio of 70 / 12 / 13 / 1 / 1 in the presence of oligomer 5. The performance characteristics of the resulting aqueous emulsion are shown in Table 7 below:

[0122] Table 7

[0123]

[0124] Example 11

[0125] Preparation of hydrophobic polymer 6

[0126] Hydrophobic polymers were prepared using the method of Example 6, employing a rigid, high-Tg oligomer (oligomer 4) and a soft polymer prepared in the presence of oligomer 4 using diacetone acrylamide as an adhesion-promoting olefinic unsaturated comonomer, 1,6-hexanediol diacrylate as a chain extender, and BA / BMA / MMA / DAAM / HDDA in a ratio of 70 / 12 / 16 / 1 / 1. The performance characteristics of the resulting aqueous emulsion are shown in Table 8 below.

[0127] Table 8

[0128]

[0129]

[0130] Comparative Example

[0131] ADH-containing polymers

[0132] The performance characteristics of two commercially available aqueous emulsions containing ADH (NEOCRYL XK-98 self-crosslinking acrylic emulsion polymer and NEOCRYL XK-232 self-crosslinking anionic acrylic copolymer emulsion) were evaluated. The results, along with those for hydrophobic polymers 3 and 4, are listed in Table 9 below. The presence of ADH in the commercially available emulsions was confirmed by liquid chromatography-mass spectrometry (LC-MS), while the emulsions of hydrophobic polymers 3 and 4 did not contain ADH.

[0133] Table 9

[0134]

[0135] The results in Table 9 indicate that the NEOCRYL XK-98 polymer exhibits slightly higher anti-blocking and water resistance than hydrophobic polymers 3 and 4, but is more brittle. The NEOCRYL XK-232 copolymer demonstrates comparable anti-blocking and slightly greater water resistance compared to hydrophobic polymers 3 and 4, lower anti-blocking than XK-98, and greater elasticity (assessed by measuring the percentage of free film elongation) compared to all three polymers. The results in Table 9 and the aforementioned LC-MS results suggest that coating formulations based on hydrophobic polymers 3 or 4 should perform comparably to those based on NEOCRYL XK-98 and NEOCRYL XK-232, while avoiding the use of ADH and the related concerns regarding aquatic organism toxicity discussed in Committee Decision (EU) 2016 / 397 of 16 March 2016.

[0136] Example 12

[0137] Transparent coating

[0138] Prepare transparent coating formulations using the ingredients shown in Table 10 below:

[0139] Table 10 Transparent Coating Preparations

[0140] Element Wt.% Hydrophobic polymer of Example 6 54.0 water 42.6 ammonia 0.2 <![CDATA[TEGO FOAMEX TM 822 Defoamer (Evonik Inds.) 0.2 <![CDATA[TEGO AIREX TM 902W Defoamer (Evonik Inds.) 0.2 <![CDATA[SILTECH TM C-204 wetting agent (Siltech Corp.) 0.2 <![CDATA[TINUVIN TM 292 Light Stabilizer (BASF) 0.5 TINUVIN 1130 light stabilizer (BASF) 1.0 <![CDATA[MERGAL TM 721 K3 preservative (Troy Corp.) 0.1 Acrysol RM 2020 Rheology Modifier (Dow Chemical) 0.6 Acrysol RM 8W Rheology Modifier (Dow Chemical) 0.4 total 100.0

[0141] The preparation was applied to the wood panels and allowed to dry. Several coated panels were then exposed to simulated outdoor weathering using a QUV Accelerated Weathering Tester from Q-Lab Corporation and method EN 927-6. Figure 1 Plate A in the figure is the unexposed plate. The upper third of the luminescent portion of plates B and C represents the unexposed portion, where the plates are clamped in a QUV testing machine. The exposed lower portions of plates B and C show only slight discoloration after total exposure of 1000 hours (Figure B) and 2000 hours (Figure C). Very favorable simulated outdoor weathering results indicate that the transparent coating made using the disclosed polymer should exhibit very good service life when used outdoors.

[0142] Example 12

[0143] Wood coloring

[0144] A reddish-brown wood pigment formulation was prepared by adding 1.5% by weight of a mixture of clear red iron oxide, clear yellow iron oxide, and lampblack to the formulations in Table 10. The pigment was applied to the edges and sides of the wood panels and allowed to dry. In a comparative test, the wood panels were coated with a similar formulation prepared using NEOCRYLXK-98 instead of the hydrophobic polymer of Example 6 in the formulations in Table 10.

[0145] The coated boards were exposed outdoors for 26 months, including more than two full winters. Figure 2 Plate D was not exposed. Plates E and F were exposed, coated with the control formulation and the formulation from Table 10, respectively. Compared with the control formulation, the formulation from Table 10 exhibited better gloss retention and less discoloration. These results indicate that pigments made using the disclosed polymer exhibit very good service life when used outdoors, and that the disclosed polymer should provide an effective ADH-free alternative for pigment formulations containing NEOCRYLXK-98.

[0146] This application also includes the following exemplary embodiments:

[0147] Implementation Method 1. A method for preparing an aqueous emulsion, the method comprising:

[0148] a) Oligopolymerizing a mixture of free radical polymerizable monomers in an aqueous solution, the mixture comprising 1 to 45 wt% of an acid-functional free radical polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting free radical polymerizable comonomer, and 98.5-50 wt% of other free radical polymerizable comonomers, to form a water-soluble oligomer with a number average molecular weight (Mn) of 500-50000 and a glass transition temperature (Tg) of at least 70°C, wherein the acid-functional comonomer makes the oligomer water-soluble either by itself or by neutralization, and the adhesion-promoting comonomer imparts improved adhesion to the substrate when the coating composition containing the aqueous emulsion is applied to and dried on a wood, plastic, metal, or cement substrate;

[0149] b) In the presence of an aqueous solution of the oligomer, emulsion polymerization is performed on at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20% by weight of the radically polymerizable monomer to form an aqueous emulsion of a hydrophobic polymer with a Tg at least 40°C lower than that of the oligomer, wherein the weight of the oligomer is 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C and a Koenig hardness of at least 40 seconds upon drying.

[0150] Embodiment 2. A coating composition comprising an aqueous emulsion of a hydrophobic polymer, said hydrophobic polymer being made from at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20 wt% based on the weight of said radically polymerizable monomer, said hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer, said oligomer being made in the aqueous solution from a mixture of radically polymerizable monomers, said mixture comprising 1 to 45 wt% of an acid-functionalized radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5-50 wt% of other radically polymerizable comonomers; said acid-functionalized comonomer... The oligomer is water-soluble either by itself or by neutralization, and the adhesion-enhancing copolymer imparts improved adhesion to the substrate when the coating composition is applied to and dried on a wood, plastic, metal, or cement substrate; the oligomer has an Mn of 500-50000 and a Tg of at least 70°C, and the hydrophobic polymer has a Tg at least 40°C lower than that of the oligomer, wherein the weight of the oligomer accounts for 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C, and a Koenig hardness of at least 40 seconds upon drying.

[0151] Embodiment 3. A coated article comprising a substrate having a coating composition thereon, the coating composition comprising an aqueous emulsion of a hydrophobic polymer, the hydrophobic polymer being made from at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20 wt% based on the weight of the radically polymerizable monomer, the hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer, the oligomer being made in the aqueous solution from a mixture of radically polymerizable monomers, the mixture comprising 1 to 45 wt% of an acid-functional radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5-50 wt% of other radically polymerizable monomers. The coating composition comprises a basic polymeric comonomer; the acid-functionalized comonomer makes the oligomer water-soluble either by means of the oligomer itself or by means of neutralization, and the adhesion-promoting comonomer imparts improved adhesion to the substrate when the coating composition is dried; the number-average molecular weight (Mn) of the oligomer is 500-50000, the glass transition temperature (Tg) is at least 70°C, and the Tg of the hydrophobic polymer is at least 40°C lower than that of the oligomer, wherein the weight of the oligomer accounts for 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C, and a Koenig hardness of at least 40 seconds upon drying.

[0152] Embodiment 4. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the acid-functional free radical polymerizable comonomer comprises a carboxyl group.

[0153] Embodiment 5. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the acid-functional free radical polymerizable comonomer comprises an acrylic monomer.

[0154] Embodiment 6. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the adhesion-promoting free radical polymerizable comonomer comprises an aldehyde group, a ketone group, an ester group, a hydroxyl group, a silyl group or a urea group.

[0155] Embodiment 7. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the adhesion-promoting free radical polymerizable comonomer comprises acetyl methacrylate, diacetone acrylamide or a mixture thereof.

[0156] Embodiment 8. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the adhesion-promoting free radical polymerizable comonomer comprises vinylsilane.

[0157] Embodiment 9. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein the other free radical polymerizable comonomer comprises methyl methacrylate, styrene, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, or a mixture thereof.

[0158] Embodiment 10. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the oligomer is made of up to about 15% by weight of an acid-functional free radical polymerizable comonomer, up to about 5% by weight of an adhesion-promoting free radical polymerizable comonomer, and at least about 80% by weight of other free radical polymerizable comonomers.

[0159] Embodiment 11. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the oligomer is water-soluble.

[0160] Embodiment 12. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the Mn of the oligomer is about 2500 to about 5000.

[0161] Embodiment 13. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein the Tg of the oligomer is at least 80°C.

[0162] Embodiment 14. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the Tg of the oligomer is 80 to 125°C.

[0163] Embodiment 15. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein the oligomer does not contain functional groups that impart crosslinkability when the aqueous emulsion is coated onto a substrate and dried.

[0164] Embodiment 16. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the chain extender monomer comprises a bifunctional or higher functional acrylate or methacrylate; an allyl acrylate or methacrylate; an acetyl acetoxy ester of a vinyl silane or hydroxyalkyl (meth)acrylate.

[0165] Embodiment 17. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the chain extender monomer is a bifunctional chain extender monomer.

[0166] Embodiment 18. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the hydrophobic polymer is formed from about 0.1 to about 3% by weight of chain extender monomer.

[0167] Embodiment 19. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the hydrophobic polymer is formed from about 0.25 to about 1.5% by weight of chain extender monomer.

[0168] Embodiment 20. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein the hydrophobic polymer accounts for at least about 50% by weight and at most about 95% by weight of the combined weight of the oligomer and the hydrophobic polymer.

[0169] Embodiment 21. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein the hydrophobic polymer accounts for at least about 60% by weight and at most about 80% by weight of the combined weight of the oligomer and the hydrophobic polymer.

[0170] Embodiment 22. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the Tg of the hydrophobic polymer is less than about -40°C.

[0171] Embodiment 23. The method, coating composition or coated article according to any of the preceding embodiments, wherein the aqueous emulsion is substantially free of hydrolyzable crosslinking agents.

[0172] Embodiment 24. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the minimum film-forming temperature of the aqueous emulsion is from about 0 to about 55°C.

[0173] Implementation 25. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the Koenig hardness of the aqueous emulsion is about 60 to about 200 seconds.

[0174] Embodiment 26. The method, coating composition or coated article according to any of the foregoing embodiments, wherein the aqueous emulsion contains about 20% by weight to about 65% by weight of solids.

[0175] Embodiment 27. The method, coating composition, or coated article according to any of the foregoing embodiments, wherein a dried aqueous emulsion is coated and at 23°C at 1 kg / cm² 2 Two face-to-face substrates stored under pressure for 1 hour showed no adhesion.

[0176] Embodiment 28. A coated article according to any one of Embodiments 3 to 27, wherein the substrate comprises wood.

[0177] Embodiment 29. A coated article according to any one of Embodiments 3 to 27, wherein the substrate comprises plastic.

[0178] Embodiment 30. A coated article according to any one of Embodiments 3 to 27, wherein the substrate comprises metal.

[0179] Embodiment 31. A coated article according to any one of Embodiments 3 to 27, wherein the substrate comprises a cementitious material.

[0180] Embodiment 32. A coated article according to any one of Embodiments 3 to 27, wherein the substrate comprises furniture.

[0181] Embodiment 33. A coating composition or coated article according to any one of Embodiments 2 to 32, wherein the coating composition is an internal paint.

[0182] Embodiment 34. A coating composition or coated article according to any one of Embodiments 2 to 32, wherein the coating composition is an external paint.

[0183] Embodiment 35. A coating composition or coated article according to any one of Embodiments 2 to 32, wherein the coating composition is a glaze or a Lazure finish.

[0184] Embodiment 36. A coating composition or coated article according to any one of Embodiments 2 to 32, wherein the coating composition is a colorant.

[0185] Preferred embodiments of the invention have been thus described, and those skilled in the art will readily understand that the teachings found herein can be applied to other embodiments within the scope of the appended claims. The complete disclosures of all patents, patent documents, and publications are incorporated herein by reference as if they were individually incorporated.

Claims

1. A method for preparing an aqueous emulsion, the method comprising: a) Oligopolymerizing a mixture of free radical polymerizable monomers in an aqueous solution, the mixture comprising 1 to 45 wt% of an acid-functional free radical polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting free radical polymerizable comonomer, and 98.5-50 wt% of other free radical polymerizable comonomers, to form a water-soluble oligomer with a number average molecular weight (Mn) of 500-50000 and a glass transition temperature (Tg) of at least 70°C, wherein the acid-functional comonomer makes the oligomer water-soluble either by itself or by neutralization, and the adhesion-promoting comonomer imparts improved adhesion to the substrate when the coating composition containing the aqueous emulsion is applied to and dried on a wood, plastic, metal, or cement substrate; b) In the presence of an aqueous solution of the oligomer, emulsion polymerization is performed on at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20% by weight of the radically polymerizable monomer to form an aqueous emulsion of a hydrophobic polymer with a Tg at least 40°C lower than that of the oligomer, wherein the weight of the oligomer is 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C and a Koenig hardness of at least 40 seconds upon drying.

2. A coating composition comprising an aqueous emulsion of a hydrophobic polymer, said hydrophobic polymer being made from at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20 wt% based on the weight of said radically polymerizable monomer, said hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer, said oligomer being made in the aqueous solution from a mixture of radically polymerizable monomers, said mixture comprising 1 to 45 wt% of an acid-functionalized radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5-50 wt% of other radically polymerizable comonomers; said acid-functionalized comonomer The coating composition is such that the oligomer is water-soluble either by itself or by neutralization, and when the coating composition is applied to and dried on a wood, plastic, metal, or cement substrate, the adhesion-promoting comonomer imparts improved adhesion to the substrate; the oligomer has an Mn of 500-50000 and a Tg of at least 70°C, and the hydrophobic polymer has a Tg at least 40°C lower than the Tg of the oligomer, wherein the weight of the oligomer accounts for 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C, and a Koenig hardness of at least 40 seconds upon drying.

3. A coated article comprising a substrate having a coating composition thereon, the coating composition comprising an aqueous emulsion of a hydrophobic polymer, the hydrophobic polymer being made from at least one radically polymerizable monomer and at least one bifunctional or higher functional chain extender monomer in an amount of 0.1 to 20 wt% based on the weight of the radically polymerizable monomer, the hydrophobic polymer being emulsion polymerized in the presence of an aqueous solution of an oligomer, the oligomer being made in the aqueous solution from a mixture of radically polymerizable monomers, the mixture comprising 1 to 45 wt% of an acid-functional radically polymerizable comonomer, 0.5 to 20 wt% of an adhesion-promoting radically polymerizable comonomer, and 98.5-50 wt% of other radically polymerizable monomers. The copolymer contains an acid-functionalized comonomer; the acid-functionalized comonomer makes the oligomer water-soluble either by means of its own solution or by means of neutralization, and the adhesion-promoting comonomer imparts improved adhesion to the substrate when the coating composition is dried; the number-average molecular weight (Mn) of the oligomer is 500-50000, the glass transition temperature (Tg) is at least 70°C, and the Tg of the hydrophobic polymer is at least 40°C lower than that of the oligomer, wherein the weight of the oligomer accounts for 5 to 50% by weight of the oligomer plus the weight of the hydrophobic polymer; and the aqueous emulsion is substantially free of adipic acid dihydrazide, has a minimum film-forming temperature ≤55°C, and a Koenig hardness of at least 40 seconds upon drying.

4. The method, coating composition, or coated article according to any one of the preceding claims, wherein the acid-functional free radical polymerizable comonomer comprises a carboxyl group.

5. The method, coating composition, or coated article according to any one of the preceding claims, wherein the acid-functional free radical polymerizable comonomer comprises an acrylic monomer.

6. The method, coating composition, or coated article according to any one of the preceding claims, wherein the adhesion-promoting free radical polymerizable comonomer comprises an aldehyde group, a ketone group, an ester group, a hydroxyl group, a silyl group, or a urea group.

7. The method, coating composition, or coated article according to any one of the preceding claims, wherein the adhesion-promoting free radical polymerizable comonomer comprises acetyl methacrylate, diacetone acrylamide, or a mixture thereof.

8. The method, coating composition, or coated article according to any one of the preceding claims, wherein the adhesion-promoting free radical polymerizable comonomer comprises vinylsilane.

9. The method, coating composition, or coated article according to any one of the preceding claims, wherein the other free radical polymerizable comonomer comprises methyl methacrylate, styrene, ethyl acrylate, n-butyl acrylate, n-butyl methacrylate, or mixtures thereof.

10. The method, coating composition, or coated article according to any one of the preceding claims, wherein the oligomer is made of up to about 15% by weight of an acid-functional free radical polymerizable comonomer, up to about 5% by weight of an adhesion-promoting free radical polymerizable comonomer, and at least about 80% by weight of other free radical polymerizable comonomers.

11. The method, coating composition, or coated article according to any one of the preceding claims, wherein the oligomer is water-soluble.

12. The method, coating composition, or coated article according to any one of the preceding claims, wherein the Mn of the oligomer is about 2500 to about 5000.

13. The method, coating composition or coated article according to any one of the preceding claims, wherein the Tg of the oligomer is at least 80°C.

14. The method, coating composition or coated article according to any one of the preceding claims, wherein the Tg of the oligomer is 80 to 125°C.

15. The method, coating composition, or coated article according to any one of the preceding claims, wherein the oligomer does not contain functional groups that impart crosslinkability when the aqueous emulsion is coated onto a substrate and dried.

16. The method, coating composition, or coated article according to any one of the preceding claims, wherein the chain extender monomer comprises a bifunctional or higher functional acrylate or methacrylate; an allyl acrylate or methacrylate; an acetylacetoxy ester of a vinylsilane or hydroxyalkyl (meth)acrylate.

17. The method, coating composition, or coated article according to any one of the preceding claims, wherein the chain extender monomer is a bifunctional chain extender monomer.

18. The method, coating composition or coated article according to any one of the preceding claims, wherein the hydrophobic polymer is formed from about 0.1 to about 3% by weight of chain extender monomer.

19. The method, coating composition or coated article according to any one of the preceding claims, wherein the hydrophobic polymer is formed from about 0.25 to about 1.5% by weight of chain extender monomer.

20. The method, coating composition, or coated article according to any one of the preceding claims, wherein the hydrophobic polymer comprises at least about 50% by weight and at most about 95% by weight of the oligomer plus the hydrophobic polymer.

21. The method, coating composition, or coated article according to any one of the preceding claims, wherein the hydrophobic polymer accounts for at least about 60% by weight and at most about 80% by weight of the combined weight of the oligomer and the hydrophobic polymer.

22. The method, coating composition, or coated article according to any one of the preceding claims, wherein the Tg of the hydrophobic polymer is less than about -40°C.

23. The method, coating composition, or coated article according to any one of the preceding claims, wherein the aqueous emulsion is substantially free of hydrolyzable crosslinking agents.

24. The method, coating composition, or coated article according to any one of the preceding claims, wherein the minimum film-forming temperature of the aqueous emulsion is from about 0 to about 55°C.

25. The method, coating composition, or coated article according to any one of the preceding claims, wherein the Koenig hardness of the aqueous emulsion is about 60 to about 200 seconds.

26. The method, coating composition or coated article according to any one of the preceding claims, wherein the aqueous emulsion contains about 20% by weight to about 65% by weight of solids.

27. The method, coating composition, or coated article according to any one of the preceding claims, wherein the coating is a dried aqueous emulsion and is applied at 1 kg / cm² at 23°C. 2 Two face-to-face substrates stored under pressure for 1 hour showed no adhesion.

28. The coated article according to any one of claims 3 to 27, wherein the substrate comprises wood.

29. The coated article according to any one of claims 3 to 27, wherein the substrate comprises plastic.

30. The coated article according to any one of claims 3 to 27, wherein the substrate comprises a metal.

31. The coated article according to any one of claims 3 to 27, wherein the substrate comprises a cementitious material.

32. The coated article according to any one of claims 3 to 27, wherein the substrate comprises furniture.

33. The coating composition or coated article according to any one of claims 2 to 32, wherein the coating composition is an internal paint.

34. The coating composition or coated article according to any one of claims 2 to 32, wherein the coating composition is an external paint.

35. The coating composition or coated article according to any one of claims 2 to 32, wherein the coating composition is a glaze or a Lazure finish.

36. The coating composition or coated article according to any one of claims 2 to 32, wherein the coating composition is a colorant.

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