Glycol ether amines for aqueous two-component polyurethane coatings

Abstract

The present invention provides aqueous compositions comprising (i) a dispersion of an aqueous acrylic or vinyl polymer wherein the polymer comprises on average two or more hydroxyl groups or contains a polyol, (ii) one or more pigments, extenders or colorants, or a combination thereof, and (iii) one or more pigments, extenders or colorants, or combinations thereof, and (iii) one or more glycol ether amines having the following formula I: wherein R1 is a C1 to C6 alkyl group, or preferably a C3 to C4 alkyl group, R2 and R3 are independently CH3 or CH2-CH3; and m is 1 to 6, or preferably 1 to 2. The aqueous composition may also include a water dispersible polyisocyanate curing agent, thereby forming a curable aqueous coating composition that forms a polyurethane coating or film. # imgabs0 #

Description

[0001] The present invention generally relates to aqueous compositions comprising (i) an aqueous acrylic or vinyl polymer dispersion, wherein the polymer comprises an average of two or more hydroxyl groups or contains a polyol, (ii) one or more pigments, extenders or colorants, or combinations thereof, and (iii) one or more glycol ether amines. More specifically, the present invention relates to aqueous coating compositions useful as pigment dispersions and isocyanate-curable aqueous coating compositions comprising polyols or aqueous acrylic or vinyl polymer dispersions containing hydroxyl groups, one or more pigments, extenders and / or colorants, and one or more glycol ether amines. The aqueous compositions provide increased pH and pigment dispersion stability, and readily form polyurethane coatings having acceptable appearance and film properties when combined with a water-dispersible polyisocyanate curing agent.

[0002] The polyurethane comprises repeating units containing urethane groups of formula (A):

[0003] —O—C(═O)—N<(A).

[0004] Polyurethanes have found many uses in the chemical and related industries. Examples of such uses are the preparation of coatings, sealants and adhesives. Polyurethanes are typically prepared by curing a mixture of two reactants (such as separate components) that react together to produce the polyurethane. Known aqueous two-component polyurethane coating compositions comprising water-dispersible isocyanates and emulsion polymers can significantly reduce the volatile organic content (VOC) level of the coatings prepared therefrom and have reasonable cure speeds, but still cannot provide composition stability and dry film properties at the level of solvent-based polyurethane compositions. Therefore, there is still a need for a pH neutralizer that enables better pigment dispersions and pH stability in aqueous compositions without adversely affecting the dry film properties of the coatings made therefrom.

[0005] Although usually only used at 0.1% to 1% by weight of the total formulation, pH neutralizers affect the overall performance of waterborne coating compositions. Depending on the formulation, formulation designers have several options for adjusting the pH in their formulations. The most commonly used neutralizer is ammonia, which has a strong odor, making it unsuitable for low-odor coatings. Organic amines (such as 2-amino-2-methyl-1-propanol) are accepted by the coating industry for their multifunctional benefits (such as pH stability, improved pigment dispersions, and low odor) in addition to pH neutralization. However, particularly for industrial coating applications, there is still a need for an organic amine neutralizer that provides the benefits of a low-odor organic amine neutralizer and an improved pigment or colorant dispersion without adversely affecting the application or final coating.

[0006] U.S. Patent No. 5,626,915 to Laura et al. discloses an aqueous coating composition comprising: (i) a polyol; (ii) a surfactant, such as a nonionic surfactant; (iii) a halogenated polyolefin resin material or other similar halogenated resins, such as a PVC resin; (iv) an aliphatic amine, such as an amino-substituted alkanol, such as aminopropanol; and (v) water. The amine may be selected from the group consisting of alkylamines, alkyldiamines, alkanolamines, dialkanolamines, tertiary amines, poly(oxyalkylene)diamines, and mixtures thereof. Laura et al. disclose a coating having enhanced adhesion to a substrate. However, Laura et al. fail to disclose a composition having improved pH or dispersion stability.

[0007] The present inventors have sought to solve the problem of providing an aqueous composition which exhibits improved pigment dispersion and pH stability and which enables the formation of polyurethane coatings without adversely affecting the dry film properties of the polyurethane coatings formed using them. Summary of the invention

[0008] According to the present invention, the aqueous composition comprises:

[0009] (i) an aqueous acrylic or vinyl polymer dispersion, wherein the polymer contains an average of two or more hydroxyl groups, such as a portion of the polymer itself, or contains a polyol, such as a polyol absorbed in or adsorbed on the polymer,

[0010] (ii) one or more pigments, extenders or colorants, or combinations thereof, and,

[0011] (iii) one or more glycol ether amines having the following formula I:

[0012]

[0013] Where R 1 is a C1 to C6 alkyl group, preferably a C3 to C4 alkyl group; R 2 and R 3 and m is 1 to 6, or preferably 1 to 2. In addition, the composition may contain (iv) one or more coalescing solvents, such as alkyl glycol ethers, for example propylene glycol methyl ether.

[0014] (iii) a suitable amount of one or more glycol ether amines may be in the range of 0.1 wt % to 2 wt %, or preferably 0.1 wt % to 1.5 wt %, based on the total weight of the aqueous composition. The aqueous composition may contain 15 wt % to 50 wt %, or preferably 20 wt % to 45 wt % (as solids) of (i) an acrylic or vinyl polymer containing an average of two or more hydroxyl groups, based on the total weight of the aqueous composition. The aqueous composition may have a total solids content of 20 wt % to 70 wt %, or preferably 25 wt % to 65 wt %, based on the total weight of the aqueous composition. The aqueous composition may further contain a water-dispersible polyisocyanate curing agent containing one or more polyisocyanates, thereby forming a curable aqueous coating composition, such as a composition in which the curing agent has not yet reacted into the aqueous acrylic or vinyl polymer. In the aqueous coating composition of the present invention, the ratio of the isocyanate equivalents in the water-dispersible polyisocyanate curing agent to the total number of hydroxyl group equivalents in the aqueous acrylic or vinyl polymer dispersion may be, for example, in the range of 0.7: 1.0 to 2.0: 1.0, or preferably 0.75: 1 to 1.4: 1. Preferably, one or more of the aqueous composition and the aqueous coating composition, or more preferably, both, are substantially free of volatile organic compounds, or have a total of 50 g / l or less of such compounds.

[0015] In another aspect of the present invention, a method for forming a coating comprises mixing the aqueous composition of the present invention with a water-dispersible polyisocyanate curing agent component to form an aqueous coating composition, applying the aqueous coating composition to a substrate or a support such as a film, and curing to form a coating or film on the substrate or support. DETAILED DESCRIPTION

[0016] The aqueous composition of the present invention comprises a storage-stable aqueous acrylic or vinyl polymer dispersion containing pigments, colors or extenders, which comprises one or more glycol ether amines exhibiting excellent pH stability and low viscosity. The aqueous acrylic or vinyl polymer dispersion comprises a polymer, such as a copolymer of hydroxyalkyl (meth) acrylate and alkyl (meth) acrylate, each polymer chain of which has an average of two or more hydroxyl groups or as a side chain group, or it comprises at least one polyol in a polymer composition, wherein the polymer acts as a carrier, absorbent or adsorbent; and the glycol ether amine according to the present invention comprises an alkylamine (oligo) glycol ether having 1 to 6 ether groups and one hydroxyl group. When the aqueous composition also comprises a water-dispersible polyisocyanate curing agent, they are easy to provide a urethane coating from an aqueous medium. Thus, the composition enables the easy formulation of waterborne pigmented or opaque coatings prepared by way of an emulsion polymer formulation that can be made into a urethane-forming waterborne coating composition that provides good dry film properties of appearance, gloss and early water resistance suitable for industrial or architectural coatings or waterborne wood stains or sealants.

[0017] Unless otherwise indicated, temperature and pressure conditions are room temperature (23° C.) and standard pressure (101.3 kPa), also referred to as “ambient conditions.” Also, unless otherwise indicated, all conditions include a relative humidity (RH) of 50%.

[0018] Unless otherwise indicated, any term containing brackets refers alternatively to the entire term as if the brackets were present as well as the term without the brackets, and combinations of each alternative. Thus, as used herein, the term "(meth)acrylate" and similar terms are intended to include acrylates, methacrylates, and mixtures thereof.

[0019] The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Unless defined otherwise, the terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0020] All ranges recited are inclusive and combinable. For example, a disclosed amount of (iii) one or more glycol ether amines in the range of 0.1 wt % to 2 wt %, or preferably 0.1 wt % to 1.5 wt %, based on the total weight of the aqueous composition, would include amounts of 0.1 wt % to 2 wt %, or 1.5 wt % to 2 wt %, or preferably 0.1 wt % to 1.5 wt %.

[0021] As used herein, the term "addition polymer" means an acrylic polymer or a vinyl polymer prepared by free radical addition (eg, initiation, polymerization).

[0022] As used herein, the term "aqueous" means that the continuous phase or medium is water and comprises 0 wt % to 50 wt % of water-soluble compounds based on the weight of the medium. Preferably, "aqueous" refers to water.

[0023] As used herein, the term "aqueous" means water or a mixture of water with a small amount (not more than 50% by weight, based on the total weight of water and any solvents) of one or more water-soluble solvents, or preferably a mixture of water with 10% by weight or less (based on the total weight of water and any solvents).

[0024] As used herein, the term "ASTM" refers to publications of ASTM International, Conshohocken, Pa.

[0025] As used herein, the term "component" refers to a composition containing one or more ingredients that is combined with another component to initiate a reaction, polymerization, or curing. The components are stored separately until combined at the time of use or reaction.

[0026] As used herein, the term "curing" means subjecting to conditions effective for a chemical transformation or a chemical transformation under such conditions.

[0027] As used herein, unless otherwise indicated, the term "calculated Tg" or "calculated glass transition temperature" refers to the Tg of a polymer calculated using the Fox equation (TGFox, Bull. Am. Physics Soc., Vol. 1, No. 3, p. 123 (1956)). For reference and use in calculating Tg, a comprehensive compilation of available data describing the glass transition temperature of homopolymers of suitable monomers can be found in Polymer Handbook, Vol. 1, edited by Brandrup, J., Immergut, EH, Grulke, EA, 1999, p. VI / 193-277.

[0028] As used herein, the term "dispersion polymer" means a polymer dispersed in a continuous medium. Aqueous dispersion polymers are dispersed in water and include both emulsion polymers used to prepare aqueous dispersions and polymers dispersed in water after preparation.

[0029] As used herein, the term "hydroxyl functionality" refers to the average number of hydroxyl groups per molecule and, for addition polymers or oligomer chains, is the number average molecular weight (M) of the polymer. n) multiplied by the weight fraction (WF) of the total hydroxyl-functional monomers used to make the polymer (1 is 100 wt %, 0.1 is 10 wt %), divided by the hydroxyl equivalent weight (HEW) of the monomer or divided by the weighted average hydroxyl equivalent weight of a mixture of two or more monomers. For example, for hydroxyalkyl (meth)acrylate (HEMA), the hydroxyl functionality is 1 and the hydroxyl equivalent weight is the same as its molecular weight; for cyclohexanedimethanol, the hydroxyl functionality is 2 and the hydroxyl equivalent weight is half of its molecular weight. For a 10,000 M n and a HEMA-containing polymer comprising 10 wt % HEMA based on the total weight of monomers used to prepare the polymer, the hydroxyl functionality being (M n X WF / HEW or (10,000 x 0.1) / 130.1 or 7.69 hydroxyl groups per polymer molecule.

[0030] As used herein, in the case of acrylic or vinyl emulsion polymers containing two or more hydroxyl groups, the term "hydroxyl equivalent weight" is calculated based on the following theoretical calculation: take the molecular weight of a hydroxyl functional monomer (such as HEMA) or a (non-volatile) polyol (such as cyclohexanedimethanol), multiply by the hydroxyl functionality of the monomer or polyol in question, and multiply by the weight fraction of such hydroxyl functional monomer or polyol in the aqueous acrylic or vinyl polymer dispersion (1 being 100 wt. % and 0.1 being 10 wt. %). For commercially available polyols, the HEW given is as reported by the manufacturer without further determination unless otherwise stated.

[0031] As used herein, the term "isocyanate functionality" refers to the average number of isocyanate groups per molecule and, for addition polymers or oligomer chains, is the number average molecular weight (M) of the polymer. n ) multiplied by the weight fraction (WF) of the total isocyanate functional monomers used to prepare the vinyl or acrylic polymer (1 is 100 wt %, 0.1 is 10 wt %), divided by the isocyanate equivalent weight (IEW) of the monomer or divided by the weighted average isocyanate equivalent weight of a mixture of two or more monomers. For example, for isocyanoethyl methacrylate (IEM), the hydroxyl functionality is 1 and the isocyanate equivalent weight is the same as its molecular weight; for hexamethylene diisocyanate, the hydroxyl functionality is 2 and the hydroxyl equivalent weight is half of its molecular weight. For a monomer having an M of 10,000 n and an IEM-containing polymer comprising 10 wt % of IEM based on the total weight of monomers used to prepare the polymer, the isocyanate functionality being (M n X WF / HEW or (10,000 x 0.1) / 155.2 or 6.44 isocyanate / polymer molecules.

[0032] As used herein, the term "isocyanate equivalent weight" is the isocyanate equivalent weight (IEW) of a given molecule as reported by the manufacturer without further measurement multiplied by the number of grams of the molecule used, or the number of isocyanate equivalents in a given molecule multiplied by the number of moles of the molecule used.

[0033] As used herein, the term "ISO" refers to publications of the International Organization for Standardization, Geneva, CH.

[0034] As used herein, unless otherwise specified, the term "measured glass transition temperature" or "measured Tg" refers to the glass transition temperature of a material as determined by differential scanning calorimetry (DSC) scanning between -90°C and 150°C while heating at a rate of 10°C / min. Tg is the inflection point of a curve of heat flow versus temperature or the maximum value on a graph of its derivative.

[0035] As used herein, the term "(meth)acrylate" means acrylate, methacrylate, and mixtures thereof, and the term "(meth)acrylic" as used herein means acrylic, methacrylic, and mixtures thereof.

[0036] As used herein, unless otherwise specified, the term "polyol" includes diols, triols, and hydroxy-functional molecules having four or more hydroxyl groups.

[0037] As used herein, unless otherwise specified, the term "polyol solids" refers to diols or polyols or acrylic or vinyl dispersion polymers and excludes water and any solvents.

[0038] As used herein, the term "polyester polyol" means a subclass of polyols that are organic molecules having at least two alcohol (-OH) groups (preferably including α and ω-OH) and at least one carboxylate (CO2-C) functionality. The term "alkyd resin" means a subclass of polyester polyols, which are fatty acid-modified polyester polyols in which at least one carboxylate functionality is derived from the alcohol -OH of the polyol and the (C8-C 60 )Esterification reaction between the carboxyl groups of fatty acids.

[0039] As used herein, unless otherwise specified, the term "polyisocyanate" refers to any isocyanate functional molecule having two or more isocyanate groups.

[0040] As used herein, the term "polymer" refers in the alternative to a polymer prepared from one or more different monomers, such as a copolymer, terpolymer, tetrapolymer, pentapolymer, etc., and may be any of a random polymer, a block polymer, a grafted polymer, a sequential polymer, or a gradient polymer.

[0041] As used herein, the term "based on the total weight of monomers used to prepare the copolymer" refers to the total amount of monomers as solids and does not include chain transfer agents.

[0042] As used herein, the term "substantially free of volatile organic compounds" means that the composition contains less than 50 g / l, or preferably less than 25 g / l, of organic solvents (including glycol ether amines), coalescing solvents, and all other organic solvents in a given composition, in a total amount, based on the total weight of the composition.

[0043] As used herein, the term "total solids" refers to anything in a given composition other than water and volatile solvents that flash or evaporate at 40°C or below and atmospheric pressure. Thus, coalescing solvents and glycol ether amines are not considered solids. The diols and polyols that are reacted to form a given composition are considered solids.

[0044] As used herein, the phrase "wt %" means percent by weight.

[0045] The aqueous composition according to the present invention comprises (i) an aqueous acrylic or vinyl polymer dispersion, wherein the polymer itself contains an average of two or more hydroxyl groups, or wherein each molecule of the polymer in the dispersion includes an average of at least one polyol molecule, such as a diol, a polyol or an oligomer thereof, which is complexed or reacted with (adsorbed onto) or absorbed into (absorbed into) a polymer that can serve as a carrier. The aqueous acrylic or vinyl dispersion polymer can be a multi-stage polymer that absorbs a polyol. The aqueous composition further comprises (ii) one or more pigments, extenders or colorants or combinations thereof. In addition, the aqueous composition further comprises (iii) one or more organic glycol ether amines of the following formula I:

[0046]

[0047] Where R 1 is a C1 to C6 alkyl group, preferably a C3 to C4 alkyl group; R 2 and R 3 and m is 1 to 6, or preferably 1 to 2. In addition, the composition may contain (iv) one or more coalescing solvents, such as alkyl glycol ethers, for example propylene glycol methyl ether.

[0048] (i) The aqueous acrylic or vinyl polymer dispersion contains an average of two or more hydroxyl groups which may be part of the polymer itself, such as in the polymer backbone or as a side chain, or as a polyol that is post-reacted with (absorbed into) the polymer or otherwise contained or absorbed in the dispersion (e.g., imbibed or absorbed in a polymer in the aqueous acrylic or vinyl polymer dispersion).

[0049] Suitable aqueous acrylic or vinyl polymer dispersions may include acrylic, styrene-acrylic, styrene-butadiene, olefin, vinyl chloride, ethylene vinyl acetate and polyethylene vinyl acetate emulsion polymers, preferably acrylic and styrene-acrylic. The aqueous dispersion polymer composition may have multiple segments, each segment having a separately measured glass transition temperature or Tg (measured Tg), wherein at least one measured Tg is from -10°C to 100°C, preferably from 20°C to 80°C. If the measured Tg of the emulsion polymer is too high, suitable aqueous compositions including them may require excess solvent for processability. If the measured Tg of the polymer is too low, coatings made from them may suffer from low hardness.

[0050] (i) Aqueous acrylic or vinyl polymer dispersions may be formed by conventional methods, such as, for example, free radical emulsions or aqueous addition polymerization in the presence of free radical initiators (e.g., peracids or salts thereof) to form aqueous acrylic or vinyl polymer dispersions by addition polymerization. Monomers may be added to the polymerization as a single feed for higher molecular weight products or by stepwise addition polymerization for lower molecular weight or multiphase polymers. It may also be advantageous to add monomers to the polymer in uneven stages to form multiphase polymer particles to produce core-shell, hemispherical or occluded morphologies.

[0051] Monomers suitable for preparing (i) aqueous dispersions or emulsion polymers include alkyl (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, vinyl esters, vinyl ethers, allyl ethers, vinyl aromatics, such as styrene, and combinations thereof. As used herein, the term "(meth)acrylic acid" refers to methacrylic acid or acrylic acid. Additional monomers can be used to prepare aqueous acrylic or vinyl polymer dispersion polymers, including carboxylic acid monomers such as (meth)acrylic acid and itaconic acid, and their salts; sulfonic acid monomers, such as sodium styrene sulfonate and acrylamide-methyl-propane sulfonate and their salts; and phosphoric acid monomers, such as phosphoethyl methacrylate and its salts. Monomers such as styrene, acrylonitrile and acetoacetoxyethyl methacrylate (AAEM), as well as monomers capable of imparting co-curable functional groups (such as glycidyl (meth)acrylate and hydroxyalkyl (meth)acrylate) can also be used to prepare aqueous acrylic or vinyl polymer dispersions. When using AAEM, it may be desirable to post-react the polymer of the (meth)acrylate monomer with a primary amine or ammonia to form a polymer containing the corresponding enamine, acetoacetoxyethyl methacrylate enamine.

[0052] In order to form a harder or rubbery phase in the (i) aqueous acrylic or vinyl polymer dispersion, or to increase its polyol absorption capacity, it may be advantageous to incorporate into the polymer a small amount of a copolymerized multiethylenically unsaturated monomer group including allyl (meth)acrylate, diallyl phthalate, 1,4-butanediol di(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate and divinylbenzene.

[0053] Chain transfer agents can be used to control the molecular weight of (i) the waterborne acrylic or vinyl dispersion polymer during polymerization. Examples of chain transfer agents include dodecyl mercaptan, butyl mercaptopropionate, methyl mercaptopropionate, hydroxyl group-containing mercaptans such as hydroxyethyl mercaptan, and mercaptopropionic acid.

[0054] Examples of suitable (i) waterborne acrylic or vinyl dispersion polymers may include acrylic and styrene-acrylic polymers and acrylic and vinyl copolymers from vinyl acetate, preferably acrylic and styrene-acrylic polymers having an average of two or more hydroxyl groups.

[0055] Suitable (i) aqueous acrylic or vinyl polymer dispersions having an average of two or more hydroxyl groups may include those formed by conventional methods. In such polymers, the hydroxyl group functionality may be provided by hydroxyl functional vinyl or acrylic monomers such as hydroxyethyl methacrylate (HEMA), caprolactone (meth)acrylate or allyl alcohol, or via condensation of a diol or polyol in copolymerized form with a carboxyl group-containing monomer, post-polymerized to form hydroxyl group-containing side chains, or via absorption or adsorption of a polyol into a polymer, such as absorption or adsorption into a multistage polymer having crosslinked stages after polymerization.

[0056] In one example of an aqueous acrylic or vinyl polymer dispersion according to the present invention (i) comprising an average of two or more hydroxyl groups of a polymer, the aqueous dispersion of the acrylic polymer may contain a hydroxyl-containing monomer in polymerized form, such as hydroxyethyl methacrylate (HEMA) or hydroxypropyl methacrylate. In another example, the acrylic or vinyl polymer may contain a carboxyl-containing monomer in copolymerized form, such as (meth) acrylic acid, on which a polyol (i.e., a diol) is adsorbed to form a polyol-containing polymer, which is capable of forming a polymer by step-growth polymerization with a water-dispersible polyisocyanate, for example. Such acrylic polymers can be prepared by emulsion polymerization, by suspension addition polymerization, followed by dispersion with a surfactant or emulsifier, or by dispersing a preformed polymer into an aqueous medium under shear, such as in the presence of a surfactant or emulsifier, followed by adsorption of a polyol into the polymer under shear.

[0057] To formulate a composition of a polyol absorbed or adsorbed (chemically reacted) onto (i) an aqueous acrylic or vinyl polymer dispersion composition, the polymer itself may be combined with the diol or polyol composition in pure form (for water soluble diols or polyols) or in aqueous dispersion form (for less water soluble diols or polyols). In the aqueous dispersion of the polyol, the diol or polyol is preferably micronized and stabilized with a stabilizing amount of a surfactant, preferably at a concentration in the range of about 0.5 wt % to 5 wt % based on the total solids in the aqueous dispersion, and then mixed with the aqueous acrylic or vinyl polymer dispersion. Nonionic surfactants are preferred, including nonionic wetting agents that do not contain alkylphenol polyoxyethylene ethers (APEOs), such as polyalkylene oxide block copolymers, polyoxyethylene glycol alkyl ethers, glucoside alkyl ethers, fatty acid esters, glycerol alkyl esters, sorbitan alkyl esters, and polyoxyethylene glycol alkylphenol ethers, including commercially available wetting agents such as TRITON TM HW-1000 alkyl ethoxylate (Dow Chemical, Midland, Mich.).

[0058] Suitable polyols that can be added to, absorbed in, or adsorbed into (i) the aqueous acrylic or vinyl polymer dispersion may include, for example, any polyol that will provide an acceptable polyurethane. These may include diols such as ethylene glycol, propylene glycol, diethylene glycol, propylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 1,4-butanediol, 1,3-butylene glycol, 2,3-butylene glycol, 1,2-butanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 1,4-pentanediol, 2,3-dimethyltrim ... alcohol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, spiroethylene glycol and dihydroxymethyl tricyclodecane; hydroxycarboxylic acids such as 2,2-dihydroxymethylpropionic acid, 2,2-dihydroxy 2,2-dihydroxymethylbutyric acid, 2,2-dihydroxymethylpentanoic acid, 2,2-dihydroxymethylhexanoic acid, 2,2-dihydroxymethyloctanoic acid; polylactone diols obtained by adding lactone compounds such as ε-caprolactone to such diols; ester diol compounds such as bis(hydroxyethyl)terephthalate; polyether diol compounds such as alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol and polybutylene glycol; polyester diol compounds such as bis(hydroxyethyl)terephthalate and bis(hydroxyalkyl)terephthalate; The invention also includes the following: polyols comprising polyols (alkyl) poly(alkylene terephthalates) or reaction products of excess polyols with dicarboxylic acids; trivalent or higher polyols such as glycerol, trimethylolethane, trimethylolpropane, diglycerol, triglycerol, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol and mannitol; and polylactone polyols obtained by adding lactone compounds such as ε-caprolactone to such trivalent or higher polyols.

[0059] Preferably, the polyol included in (i) the aqueous acrylic or vinyl polymer dispersion comprises any alicyclic diol or polyol having a molecular weight of 100 to 500 and containing one or more 4- to 7-membered aliphatic rings, or is made of alicyclic diols or polyols having a molecular weight of 100 to 500 and comprises at least 30% by weight of alicyclic diols and / or polyols, and any oligomeric diol or polyol having a weight average molecular weight of 200 to 3000, preferably 200 to -2000, more preferably 200 to 1000, to achieve a coating composition that is substantially free of VOCs and has acceptable film-forming properties. Such polyols include, for example, cyclohexanedimethanol (CHDM), in particular 1,3CHDM, 1,4CHDM, mixtures thereof; dianhydro-d-glucitol having two 5-membered rings each containing an oxygen atom; 4,8-bis(hydroxymethyl)tricyclo[5.2.1.0 2,6 ] decane; 2,2,4,4-tetramethylcyclobutanediol, which contains 4-membered rings and their oligomers, which include at least 30% by weight, preferably at least 40% by weight of alicyclic diols and / or condensation reaction products of polyols containing one or more 4- to 7-membered aliphatic rings based on the total weight of the reactants used to prepare the oligomers. See, for example, US20140170327A1, Dombrowski et al. These may include, for example, oligoesters or polyesters, short-chain alkyd resins, oligocarbonates or polycarbonates, oligoethers or polyethers, and oligomeric lactones or polylactones having a desired low molecular weight. Such oligomers may be prepared by conventional methods (such as by bulk polymerization). For example, polyesters may be prepared, for example, by diacids or difunctional anhydrides or their salts, cycloaliphatic diols or triols having one or more 4- to 7-membered aliphatic rings.

[0060] Preferably, to improve coating film properties such as hiding power, the (i) aqueous acrylic or vinyl polymer dispersion of the present invention may include a multistage polymer, preferably an acorn polymer, such as those described in, for example, U.S. Pat. No. 7,179,531 (B2), which comprises a first polymer stage formed from monomers providing pendant pigment adsorbing functional groups such as phosphite groups, phosphite groups, polyacid side chains, and mixtures thereof, and in a second polymer stage comprises a copolymerization product of a hydroxyl group-containing monomer such as hydroxyethyl (meth)acrylate or allyl alcohol. In the multistage hydroxyl-functional (i) aqueous acrylic or vinyl polymer dispersion, copolymerizable hydroxyl group functional monomers are included by staged free radical polymerization in one or more phases of the emulsion polymer particles to provide advantages such as faster film drying speed. For example, this may include placing all of the HEMA in one stage or in the core or shell of a core-shell emulsion polymer, as opposed to a uniform distribution of the HEMA in two or all phases or stages.

[0061] Suitable amounts of (i) aqueous acrylic or vinyl polymer in the aqueous dispersion composition of the present invention may range from 15 to 50 wt %, or preferably from 20 to 45 wt % (as solids), based on the total weight of the aqueous composition.

[0062] The aqueous composition of the present invention also comprises (ii) one or more pigments, extenders or colorants or mixtures thereof. Examples of suitable pigments may include, for example, titanium oxide, zinc white, iron oxide, carbon black, blue (such as azurite or Egyptian blue), ferrocyanide oxide (such as Prussian blue pigment) and cobalt blue (oxidation) pigments; effect pigments, such as aluminum powder, mica powder and titanium oxide coated mica powder. Suitable extenders may include, for example, talcum powder, clay, kaolin, barium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon dioxide and alumina white. Colorants may include organic and metal organic compounds that may also be referred to as pigments, such as phthalocyanine azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, indanthrene pigments and perylene pigments. Colorants need only be used in small quantities and are therefore combined with extenders or inorganic pigments.

[0063] (i) The suitable total amount of one or more pigments, extenders or colorants or their combination in the aqueous composition of the present invention can be in the range of 5 wt % to 85 wt %, or 5 wt % to 75 wt %, or 10 wt % or more, or up to 65 wt %, or preferably 20 wt % to 55 wt % based on the total weight of the aqueous composition. Suitable pigment volume concentration (% PVC) in the aqueous composition of the present invention can include 2% PVC to 50% PVC based on the total volume of the pigment, extender or colorant, polymer and other total solids contained in the aqueous composition, and more preferably 4% PVC to 30% PVC. % PVC is determined via microscopy of a cross section of a dry film made from the aqueous composition. Suitable amounts of colorants can be in the range of 0.01 wt % to 0.5 wt %, or 0.1 wt % to 0.4 wt %, based on the total weight of the aqueous composition.

[0064] According to the present invention, (iii) one or more glycol ether amines can be simply mixed into the aqueous composition as part of (i) the aqueous acrylic or vinyl polymer dispersion. The glycol ether amine can be used in an amount sufficient to stabilize the pH or pigment, extender and / or colorant contained in the aqueous composition. For example, a suitable amount of (iii) one or more glycol ether amines can be in the range of 0.1 wt % to 2 wt %, or preferably 0.1 wt % to 1.5 wt %, based on the total weight of the aqueous composition.

[0065] The aqueous composition according to the present invention may further comprise (iv) one or more coalescing solvents. Suitable coalescing solvents to aid film formation during drying include (di) alkylene glycol monoalkyl ethers, such as ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether, propylene glycol n-butyl ether (PnB, including those sold under the trade name DOWANOL TM Those sold under the trade name DOWANOL TM Those sold as ), 2,2,4-trimethyl-l,3-pentanediol monoisobutyrate, and combinations thereof.

[0066] (iv) Suitable amounts of one or more coalescing solvents may range from 0.1 wt% to 1 wt%, or preferably from 0.5 wt% to 1 wt%, based on the total weight of the aqueous composition. Generally speaking, the softer the polymer or the lower the measured Tg, the less coalescing solvent is used to ensure effective film formation.

[0067] The aqueous composition according to the present invention may further comprise any one of one or more pigment dispersants, defoamers, wetting agents, anti-settling agents, anti-foaming agents, thickeners or rheology modifiers, UV absorbers, light stabilizers, surface control agents or combinations thereof. The total amount of additives may be present in an amount of 10 wt % or less or 5 wt % or less based on the total weight of the aqueous composition. The wetting agent may be a VOC and should therefore be used in an amount of 1 wt % or less based on the total weight of the aqueous composition.

[0068] Waterborne coating composition

[0069] The aqueous coating composition of the present invention comprises an aqueous composition comprising (i) an aqueous acrylic or vinyl polymer dispersion, (ii) one or more pigments, extenders or colorants or combinations thereof, and (iii) one or more glycol ether amines in combination with a water-dispersible polyisocyanate curing agent. The aqueous coating composition of the present invention comprises a stable pigment dispersion that forms a polyurethane layer when cured, operatively contacting at least a portion of a substrate that can be coated. The curing agent initiates curing when mixed; and therefore, the method of using the aqueous coating composition of the present invention comprises keeping the curing agent separate until use, and combining it with the aqueous composition before applying it to a substrate or preparing a film therefrom.

[0070] Suitable polyisocyanates for use as curing agents according to the present invention may include any molecule having 2 or more isocyanate groups and dispersible or soluble in water at room or ambient temperature, as well as mixtures and combinations thereof. Such polyisocyanates may be aliphatic, aromatic, or a mixture of both. Although polyisocyanates have an average functionality of >2, preferably they have a higher average functionality of 2.5 to 10.

[0071] Examples of water-dispersible polyisocyanates include aliphatic diisocyanates and dimers and trimers thereof, such as, for example, C2 to C8 alkylene diisocyanates, such as tetramethylene diisocyanate and hexamethylene diisocyanate (HDI); alicyclic diisocyanates and dimers and trimers thereof, such as, for example, isophorone diisocyanate (IPDI) and dicyclohexylmethane diisocyanate (HMDI); aromatic diisocyanates and dimers and trimers thereof, such as toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Examples of dimers and trimers of polyisocyanates include biuret adducts, allophanates, uretdione, urethane imine, isocyanurate, oxadiazinetrione and polymethylene polyphenyl polyisocyanate. Such polyisocyanates, dimers and trimers may be used alone or in combinations of two or more. Among these polyisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and dimers or trimers of these diisocyanates can improve the flexibility of the resulting coating film.

[0072] Isocyanurate or trimer polyisocyanate compositions can be prepared by methods known in the art, for example, as disclosed by Daussin et al. in U.S. Patent Publication No. 2006 / 0155095A1, by trimerizing a cycloaliphatic diisocyanate (e.g., isophorone diisocyanate) in the presence of one or more trimerization catalysts (such as, for example, tertiary amines or phosphines or heterogeneous catalysts) and if desired in the presence of solvents and / or auxiliaries (such as cocatalysts), suitably at elevated temperature, until the desired NCO content has been reached, and then deactivating the catalyst using an inorganic or organic acid, the corresponding acyl halide and an alkylating agent, and preferably heating. Isocyanurate compositions containing isocyanurates from aliphatic diisocyanates can likewise be formed by cyclizing an aliphatic diisocyanate in the presence of one or more trimerization catalysts and then deactivating the catalyst. Any isocyanurate may be further modified by conventional methods to contain a carbamate, urea, imino-s-triazine, uretonimine, or carbodiimide moiety.

[0073] Other suitable water-dispersible polyisocyanates can include, for example, polyether-modified polyisocyanates, such as, for example, polyalkoxylated isocyanurates or isocyanate prepolymers with two isocyanate groups, such as those obtained from polyethers. A suitable polyisocyanate prepolymer composition can be formed by reacting bis(isocyanomethyl)cyclohexane and / or another aliphatic diisocyanate with monohydric alcohol, diol, diamine or monoamine, and then modified by reacting additional isocyanates to form allophanate or biuret-modified prepolymers. Such prepolymers can further include polyalkoxy or polyether chains. Alternatively, such prepolymers can be mixed with trimerization catalysts to obtain allophanate or biuret-modified polyisocyanate isocyanurate compositions. The preparation of such allophanate or biuret prepolymers, trimerization thereafter are known in the art, referring to, for example, U.S. Patent Nos. 5,663,272 and 6,028,158. Furthermore, suitable polyisocyanates can be modified by aminosulfonic acid so that they are water-dispersible. As polyisocyanates, prepolymers formed by reacting polyisocyanates or trimers, dimers or adducts thereof with compounds reactive to polyisocyanates under conditions such that isocyanate groups are present in excess can also be used. Examples of compounds reactive to polyisocyanates include compounds having active hydrogen groups, such as hydroxyl or amino groups, and therefore specific examples include polyols, low molecular weight polyester resins and amines.

[0074] Other examples of water-dispersible polyisocyanates include, for example, homopolymers of isocyanate-containing polymerizable unsaturated monomers, such as isocyanatoethyl (meth)acrylate, or copolymers of isocyanate-containing polymerizable unsaturated monomers and polymerizable unsaturated monomers other than isocyanate-containing polymerizable unsaturated monomers, such as any vinyl or acrylic or styrene monomers.

[0075] Generally, water-dispersible polyisocyanate compositions suitable as curing agents will have a solids content of 20 to 70 wt %, preferably 25 to 65 wt %, or more preferably 30 to 60 wt %.

[0076] The aqueous coating composition of the present invention may comprise an equivalent ratio of the total number of isocyanate group equivalents to the hydroxyl group equivalents in the range of 0.7:1.0 to 2.0:1.0. For example, the ratio of the isocyanate equivalents in the polyisocyanate composition component (which may comprise several different polyisocyanates) to the total number of hydroxyl group equivalents in the aqueous coating composition may be 0.8:1.0 or higher, or 1.8:1.0 or lower, or preferably in the range of 0.9:1 to 1.5:1.

[0077] The total solid content of the aqueous coating composition of the present invention may be in the range of 20 wt % to 70 wt %, preferably 25 wt % to 65 wt %, or more preferably 30 wt % to 60 wt %.

[0078] The aqueous coating composition of the present invention can be applied to the surface of a substrate or carrier (such as a film) by any suitable method (such as, for example, brushing, calendering, roller coating, spraying, wiping, smearing or dipping). In one example, in a method for coating the surface of a substrate, the method includes applying a curable aqueous coating composition to at least a portion of the surface of a substrate or carrier, and curing the curable aqueous coating composition at a curing temperature (including room temperature or ambient temperature) of 15° C. to 80° C. to prepare a coated substrate or carrier including a polyurethane coating or film thereon.

[0079] The substrate that is suitable for being coated or independently sealed can include any material that polyurethane will adhere to it.The example of suitable material is wood, metal, ceramic, plastic and glass.The surface of the substrate that is coated, adhered or sealed can be irregular or regular, continuous or discontinuous, porous or non-porous, engaged or unengaged.The substrate that is coated or sealed can be any shape, including for example flat or rolled plate (for example cylinder), ball, bead or subdivided particles.

[0080] Example

[0081] The following examples illustrate the present invention. Unless otherwise indicated, all parts and percentages are by weight, and all temperatures are in ° C., and all preparation and testing procedures are carried out under ambient conditions of room temperature (23 ° C.) and pressure (1 atm). In the examples and Tables 1, 2 and 3 below, the following abbreviations are used unless otherwise defined:

[0082] CE: comparative example; rpm: revolutions per minute; KU: Krebs unit; 3M: Minnesota Mining and Manufacturing Co.; 2-HEMA: 2-hydroxyethyl methacrylate; BA: butyl acrylate; Sty: styrene; MMA: methyl methacrylate; IBOMA: isobornyl methacrylate; MAA: methacrylic acid.

[0083] Material : All materials used to prepare the aqueous coating composition formulations are listed below in Table 1. Examples include aqueous coating compositions with four separate pH neutralizers: two comparative examples CE1 and CE2 include aminomethyl propanol and trialkanolamine, respectively; and two inventive examples 1 and 2 include glycol ether amine.

[0084] Table 1: Materials

[0085]

[0086] The waterborne coating formulations tested in the examples are listed in Table 2 below. The following formulation method was used:

[0087] Pigment grinding : During the grinding process, water, dispersant, wetting agent, defoamer and pH neutralizer were added to a 1 L plastic cylinder in the order shown in Table 2 below. Then, the mixture was dispersed by a dispersing machine equipped with a toothed dispersing plate. TM , Model SFJ-400, Shanghai XianDai Environment Engineering Technique Co., Ltd., Shanghai, PRC), i.e., a dissolver, was used to mix the mixture at 400 rpm for 10 minutes. Afterwards, the pigment was gradually added to the cylinder step by step over 30 minutes, and the dispersion speed was gradually increased to 2000 rpm. The dissolver was kept at 2000 rpm for another 30 minutes, and then the rheology modifier and water were added to obtain the pigment dispersion.

[0088] Dilution and formation of coating compositions : In the dilution process and in the part A / part B mixing process, a triple stirring paddle was used to replace the dissolver element in the dispersion machine. The materials in the dilution process listed in the following table 2 were added to the pigment dispersion in the same container for the preparation of the pigment dispersion, and the mixing speed was gradually reduced to 1000rpm and maintained at 1000rpm, mixed for 15 minutes to obtain an aqueous acrylic acid or vinyl polymer dispersion. The resulting aqueous dispersion was left to stand for 1 day (24 hours) as part A to deaerate. Then, part B was added to part A, and a dispersion machine was used to mix for 10 minutes at 600rpm.

[0089] Table 2: Coating composition formulation

[0090]

[0091] Test Method : The following test methods were used in the following examples:

[0092] Dispersion efficiency : During the pigment grinding process, after adding the pigment and before adding the rheology modifier and water, the viscosity was measured after 30 minutes of dispersion using a viscometer (BROOKFIELD TMThe KU viscosity (in Krebs units) of each paste was measured using a KU-2 viscometer (AMETEK Brookfield, Middleboro, MA). Viscosities less than 120 KU are acceptable. Lower viscosities mean higher dispersion efficiency and better pigment dispersion performance.

[0093] Part A Viscosity of the aqueous dispersion composition : Immediately after preparing the aqueous acrylic polymer dispersion of Part A, measure the viscosity using a BROOKFIELD TM KU-2 Viscometer) measures the KU viscosity of the Part A sample (record "Initial") and then again 24 hours later (record "Overnight"). Viscosities of less than 70 KU are acceptable.

[0094] pH stability : After preparing the aqueous acrylic or vinyl polymer dispersion of Part A and allowing it to stand for 24 hours, measure the pH using a pH meter (METTLER TOLEDO TM , Model S-470 scale, Mettler Toledo, Columbus, Ohio) measured pH, and the result was recorded as pH0. Then, Part A was sealed in a 250 mL plastic cylinder and placed in an oven at 50±2°C (Model: UF110, MEMMERT GmbH, Schwabach, DE). After 75 days, each sample was taken out of the oven and cooled to room temperature, the pH was measured with the same pH meter, and the result was recorded as pH1. The pH reduction after 75 days at 50°C was calculated by the following formula:

[0095]

[0096] Smaller pH variations mean better pH stability. The acceptable limit for pH variation is 5% or less.

[0097] Glossiness(60 °): Gloss was tested according to GB / T 9754-2007 (Standardization Administration of China, Beijing, PRC). After mixing Part A and Part B to form an aqueous coating composition, a coating film (150 μm thick) was drawn down on a glass plate using a rod coater. After curing at 60° C. for 45 minutes, the coating film was taken out of the oven and heated using BYK TMThe gloss was measured using a Micro-Tri-Gloss tester (BYK Chemical, Wallingford, CT).

[0098] Early water resistance :After mixing part A and part B to form an aqueous coating composition, a coating film (150 μm thick) was scraped on a tin plate by a rod coater. The coating film was cured at room temperature for 15 minutes, then cured at 60 ° C for 45 minutes, and then placed at room temperature for 1 hour. Next, the side of the tin plate was sealed with 3M tape. The sealed plate was then immersed in a deionized water bath. After 48 hours, the appearance of the coating film was visually observed and rated according to ASTM D714 (2017). The appearance grades in ASTM D714 are shown in Table 3 below. The numbers represent the size of the blister, and the letters represent the density of the blister. The performance test results are summarized in Table 4 below.

[0099] Table 3: Appearance grades in ASTM D714

[0100] Defined level abbreviation rare F middle M Medium Density MD density D Best, no rust, no blistering 10 The bigger the number, the smaller the bubbles. 9～1 All rusted 0

[0101] Table 4: Performance of waterborne coatings with various pH neutralizers

[0102]

[0103] As shown in Table 4 above, the results of Examples 1 and 2 of the present invention containing glycol ether amines corresponding to Formula (I) are excellent. In particular, Examples 1 and 2 of the present invention exhibit significant improvements in pH stability. 1 The aqueous coating composition of Example 2 of the present invention containing glycol ether amine of the group also exhibits a better dispersion efficiency than CE1, CE2, and CE3. The coatings prepared from the aqueous coating compositions of Examples 1 and 2 of the present invention exhibit very good coating film gloss and early water resistance dry film properties.

Claims

1. An aqueous composition, comprising: (i) an aqueous acrylic or vinyl polymer dispersion, wherein the polymer contains an average of two or more hydroxyl groups or contains a polyol, (ii) one or more pigments, extenders or colorants, or combinations thereof, and, (iii) one or more glycol ether amines having the following formula I: Where R 1 is a C1 to C6 alkyl group, R 2 and R 3 are independently CH3 or CH2-CH3; And m is 1 to 6.

2. The aqueous composition according to claim 1, comprising 15 to 50 wt% as solids of (i) an acrylic or vinyl polymer containing an average of two or more hydroxyl groups, based on the total weight of the aqueous composition.

3. The aqueous composition according to claim 1, wherein In Formula I, R 1 is a C3 to C4 alkyl group, and m is 1 to 2.

4. The aqueous composition according to claim 1, wherein the amount of the (iii) one or more glycol ether amines is in the range of 0.1 wt% to 2 wt% based on the total weight of the aqueous composition.

5. The aqueous composition according to claim 4, wherein the amount of the (iii) one or more glycol ether amines is in the range of 0.1 wt% to 1.5 wt% based on the total weight of the aqueous composition.

6. The aqueous composition of claim 1, further comprising (iv) one or more coalescing solvents.

7. The aqueous composition according to claim 1, which is substantially free of volatile organic compounds and the total amount of such compounds is 50 g / l or less.

8. The aqueous composition according to claim 1, further comprising a water-dispersible polyisocyanate curing agent in the aqueous coating composition, wherein the water-dispersible polyisocyanate curing agent comprises one or more polyisocyanates.

9. The aqueous composition of claim 8, wherein the ratio of the isocyanate equivalents in the water-dispersible polyisocyanate curing agent to the total number of hydroxyl group equivalents in the aqueous acrylic or vinyl polymer dispersion is in the range of 0.7:1.0 to 2.0:1.

0.

10. A method for forming a coating, the method comprising: applying the aqueous coating composition according to claim 8 to a substrate or a carrier; as well as The aqueous coating composition is cured to form a coating or film on the substrate or support.

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