WO2014018843A1 - Waterborne coatings - Google Patents

Description

WATERBORNE COATINGS

CROSS-REFERENCE TO RELATED APPLICATION

[0001 ] This application c iaims the benefi t of U. S. provisional patent application number 61 /676, 127 filed on July 26, 2012, the entirety of which is hereby incorporated by reference.

[0002J This invention relates to waterborne coatings having improved performance properties. Conventional latex paints are widely used because they provide reduced volatile organic compound emission and because they allow easier clean up than solvent borne coatings. They can provide coatings with low tendency to yellow on exposure, excellent exterior durability, flexibility, and gloss retention. However, many typical latex coatings may lack certain performance properties, such as flow and leveling open time, adhesion and other properties. Additionally, it can be difficult to provide water borne coatings having excellent physical properties while also possessing the optimum high shear and m id and low shear rate viscos ities for package stabi l ity and desirable application properties. The mid and low shear rate viscosities (typically measured at shear rates from around 50 see/⁵ to around 0. 3 see.^"1) are generally related to a coatings flow and leveling. The low shear rate viscosity must be high enough to prevent pigment settling and to minimize sagging when the coating is applied to a vertical surface.

[ΘΘΘ3] The high shear rate viscosity (typically measured at a shear rate of around 1 0,000 sec.^"!) provides brush drag when the coating is applied and aids in providing proper film thickness. In some embodiments, the coatings of this invention will have a high shear viscosity (measured at 10,000 sec.^'5) between about 1 .0 and 3.0 poise, and a mid shear rate viscosity (measured at 50 sec.^"') of between about 7,0 to 20.0 poise when measured at 46%NVM.

[0O04J it has now been found that waterborne coating compositions having improved properties, such as improved physical properties and excellent viscosity performance across a range of shear rates, can be produced by formulating a coating comprising (i) a crosslmkable binder resin having latent crosslinkirsg groups; (ii) a suitable crosslinker for the crosslinkabie binder resin; and (iii) a waterborne air-curing, monomer modified alkyd emulsion obtained by the acidolysis of a polyalkylene terephthaiate or polyalkylene naphthanate and subsequent monomer modification. For certain applications, the aikyd polymer will be based on polyethylene terephthaiate (PET) and the acidolysis will involve fatty acids or oils to provide the air-drying capabilities. This invention relates to coating compositions having a balance of properties making them suitable for a variety of architectural and industrial paint applications.

[000S| In one embodiment, this invention relates to an aqueous coating composition comprising a crosslinkable binder resin having latent crosslinking functionality, an effective crosslinking amount of a crosslinker for the binder resin, and an air-curing, monomer modified aikyd emulsion obtained by the acidolysis of a polyalkylene terephthaiate or polyalkylene naphthanate and subsequent monomer modification.

1. The Crosslinkable Binder Resin

[00061 The present invention is directed to an aqueous coating composition in which the crosslinkable binder resin has functional groups that further react with one or more co-dispersed crosslinkers some time after initial formation of the binder resin. In certain applications the substantive crosslinking will be delayed until application of the coating to a substrate and evaporation of at least some of the aqueous carrier,

|0087] As reactive elements, the crosslinkable binder resin will comprise the polymerization reaction product of at least one or more eopoiymerizable monoethylenically unsaturated monomers, wherein at least one of the monoethylenically unsaturated monomers contains latent crosslinking functionality. This crosslinkable binder resin is used in combination with a crosslinking amount of at least one crosslinker reactive with the crosslinking functionality,

[0008] The latent crosslinking functionality can be imparted to the binder resin by incorporating monomers having reactive functional groups known in the art. For example (Ϊ) the pendent functional group could be a carbonyl group, such as ketone, or aldehyde, or acetoacetoxy and the crosslinker could representatively have amino or hydrazide groups; (ii) the pendent functional group could be epoxy and the crosslinker could representatively have carboxyiic acid, thiol or amino groups; (Hi) the pendent functional group could be silane and the crosslinker could representatively have hydroxy! groups; and (iv) the pendent functional groups could be hydroxy! groups and the crossl inker could representatively have isocyanate groups or methylol groups or etherified methylol groups.

|0009] Alternatively, the functional groups identified as useful i n the crossl inkers could be incorporated into the binder resin and the corresponding identified reactive group could be present in the crosslinker. The exact nature of the coreactive groups is not critical . Any coreactive groups are poss ible as pendent functional groups and crosslinking groups, provided the coating composition remains fluid until application to a substrate. If desired, the crosslinker can be withheld from the coating composition until immediately prior to application to ensure that the coating composition remains fluid. In some embodiments, such as the use of pendent carbonyl groups on the binder resin, and the use of a water-soluble polyhydrazide, it is convenient to incorporate the hydrazide into the aqueous coating to provide a single package which will cure upon application.

|θθ!θ] The latex polymers used as cross!inkabie binder resins in accordance with the present invention include those polymers polymerized from one or more suitable monomers. Typically, the binders are polymerized from one or more copolymerizab!e monoethyienically unsaturated monomers such as, for example, vinyl monomers and/or acrylic monomers.

[SOU ] The vinyl monomers suitable for use in accordance with the present invention include any compounds having vinyl functionality, i.e., ethy!enic unsaturation, exclusive of compounds having acrylic functionality, e.g., acrylic acid, methaeryiic acid, esters of such acids, acryionitrile and acrylamides. Preferably, the vinyl monomers are selected from the group consisting of vinyl esters, vinyl aromatic hydrocarbons, vinyl aliphatic hydrocarbons, vinyl alky! ethers and mixtures thereof.

[00121 Suitable vinyl monomers include vinyl esters, such as, for example, vinyl propionate, vinyl iaurate, vi nyl pivalate, vi nyl nonanoate, vi nyl decanoate, vinyl neodecanoate, vinyl butyrates, vinyl benzoates, vinyl isopropyl acetates and similar vinyl esters; vinyl aromatic hydrocarbons, such as, for example, styrene, methyl styrenes and similar lower aikyl styrenes, chlorostyrene, vinyl toluene, vinyl naphthalene and diviny! benzene; vinyl aliphatic hydrocarbon monomers, such as, for example, vinyl chloride and vinylidene chloride as well as alpha olefins such as, for example, ethylene, propylene, isobutylene, as well as conjugated dienes such as 1 ,3 butadiene, methyl-2-butadiene, 1 ,3-piperylene, 2,3-dimethyl butadiene, isoprene, cyclohexene, cyclopentadiene, and dicyclopentadiene; and vinyl alky! ethers, such as, for example, methyl vinyl ether, isopropyl vinyl ether, n-butyi vinyl ether, and isobutyl vinyl ether.

[0013] The acryl i c monomers su itabl e for use i n accord anc e w ith the present invention comprise any compounds having acryl ic functi onal ity. Preferred acryl ic monomers are selected from the group consisting of a!kyl acrylat.es, alkyl methacryiates, acrylate acids and methacrylate acids as wel l as aromatic derivatives of acrylic and methacryl ic acid, acry!amides and acrylonitriie. Typical ly, the alkyl acrylate and methacrylic monomers (also referred to herein as "alkyl esters of acrylic or methacrylic acid") wit! have an alkyl ester portion containing from 1 to about 1 8, preferably about 1 to 8, carbon atoms per molecule,

[0014| Su itabl e acry l i c monomers i ncl ude, for exampl e , m ethyl acryl ate and methacrylate, ethyl acrylate and methacrylate, butyl acrylate and methacrylate, propyl acrylate and methacrylate, 2-ethyl hexyi acrylate and methacrylate, cyclohexyl acrylate and methacrylate, decyl acrylate and methacrylate, isodecyl acrylate and methacrylate, benzyl acrylate and methacrylate, isobornyi acrylate and methacrylate, neopentyl acrylate and methacrylate, and l~adamantyl methacrylate.

[001S] In addition to the specific monomers described above, those skilled in the art will recognize that other monomers such as, for example, allylic monomers, or monomers which impart wet adhesion, such as monomers having tertiary amine, ethylene ureido, or N- heterocyclic groups, can be used in place of, or in addition to, the speci fically described monomers in the preparation of the binders. Representative wet adhesion promoting monomers include methacrylamidoethyl ethylene urea, dimethylaminoethyl methacrylate, vinyl imidizole and 2-eihyieneuriedo-ethyl methacrylate. The amount of such other monomers i s dependent on the particul ar monomers and their intended function, which amount can be determined by those skilled in the art. in one embodiment of this invention, a wet adhesion promoting monomer, if desired, could be present at levels ranging up to about 5% of the total monomer mix by weight. [00I6J In one embodiment of the present invention the hinder resin may comprise a "single stage" poiymer which is typically obtained by admixing selected po!ymerizabie monomers in a single reaction mixture. In another useful embodiment, the binder resin may be obtained by admixing the monomers in multiple stages having different monomer compositions or concentrations at various stages of the addition. For example, the monomer mixture couid be varied as the reaction progresses to provide a sequentially formed composition, whereby essentially one polymer is prepared in the presence of another, preformed polymer. Without being l im ited to any particular theory, this polymerization process possibly, but not necessarily, results in a core/shell particle arrangement, For some, applications, the monomer mix wi l l be varied to provide one sequence of the reaction with a higher concentration of "softer" monomers (those whose homopolymers have relati vely lower glass transition temperatures (Tg) and another sequence might involve a greater concentration of "harder" monomers. In embodiments where the binder resin comprises a sequentially formed polymer composition, the iower Tg polymer (the "softer" poiymer) may be the core in a core/shell particle arrangement while the higher Tg material (the "harder" poiymer) comprises the shell . An opposite arrangement may also be used in connection with the present invention. As used herein "two-stage " polymer refers to an overal l poiymer where one polymer is essentially formed in the presence of another, preformed polymer.

|0017| The monomer mix polymerized to create the crosslinkab!e binder resin of the present invention wi ll comprise at least one ethylenical i y unsaturated monomer containing "latent crosslinking" capabilities, which as used herein means a monomer which possesses the ability to further react with a crossiinker some time after initial formation of the poiymer. The crosslinking reaction can occur through the application of energy, e. g. , through heat or radiation. Also, drying can acti vate the crossl i nking polymer through changes in pH, oxygen content, evaporation of solvent or carrier, or other changes that causes a reaction to occur. The particular method of achieving crosslinking in the binder poiymer is not critical to the present invention. A variety of chemistries are known in the art to produce crosslinking in latexes,

[0018] Representative examples of latent crosslinking carbonyl-containing monomers include acrolein, methaerolein, diacetone acryiamide, diacetone methacrylamide, 2 buianone methacryiate, formyl styrol, diaeetone acrylate, diacetone methacryiate, acetonitrile acryiate, acetoacetoxyethyl methacrylate, acetoacetoxyeihyl acrylate and vinylaceto acetate. These monomers normally do not affect crosslinking until during final film formation, for example, when the aqueous polymer emulsion simultaneously contains an appropriate added amount of a reactive material such as a polyamine compound as crossiinker. Particularly suitable compounds of this type are the dihydrazides and trihydrazides of aliphatic and aromatic dicarboxyiic acids of 2 to 20 carbon atoms. Polyamine compounds useful as cross!inkers for the carboxyl functional groups include those having an average of at least two carbonyi-reactive groups of the formula - NH, and carbonyl reactive groups derived from such groups. Examples of useful amine functional groups include R-NH2, R-O-NHj. R-0-N=C<, R-NH-C(=0)-0- NH_2> wherein R is alkylene, alicyclic or aryl and may be substituted. Representative useful poiyamines include ethylene diamine, isophorone diamine, diethyienetriamine and dibutylenetriamine. in one embodiment of this invention it is useful to utilize polyhydrazides as the polyamine compounds, Representative useful polyhydrazides include oxalic dihydrazide, adipic dihydrazide, succinic dihydrazide, malonic dihydrazide, glutaric dihydrazide, phthalic or terephtha!ic dihydrazide and itaconic dihydrazide. Additionally, water-soluble hydrazines such as ethylene-l,2-dihydraztne, propylene- 1 ,3-dihydrazine and buiylene-l,4-dihydrazine can also be used as one of the crosslinking agents.

[0019] Additional building blocks which are suitable for postcrosslinking are those which contain hydrolyzabie organosilicon bonds. Examples are the copoiymerizable monomers methaesyloyloxypropyitrimethoxysilane and vinyitrimethoxysiiane,

[Θ020] Epoxy-, hydroxy!- and/or N-alkylol-containing monomers, for example, glycidyi acrylate, N~methylolaeryiamide and -methacryiamide and monoesters of dihydric alcohols with .β-monoethylenically unsaturated carboxylic acids of 3 to 6 carbon atoms, such as hydroxyethyl, hydroxy-n-propyl or hydroxy-n-butyl acrylate and methacrylate are also suitable for postcrosslinking. Primary or secondary amino containing acrylates or methacrylates such as t-butyl amino ethyl methacryiate are also suitable. [00211 In one embodiment the binder resin cars be obtained by the polymerization of a mixture of monomers, which mixture contains about 0.5 to about 25% by weight, based on the total weight of the polymer, of at least one monomer having latent crossiinking functionality.

| 0022] In one embod iment of the present inventio n, the bi nder res i n is an acid functional latex. Specific acid functional monomers suitable for use in accordance with the present invention include, for example, acrylic acid, methacrylic acid, ethacrylic acid, itaconic aci d, maleic acid, dimeric acrylic acid or the anhydrides thereof. Besides carboxylie acids arid anhydrides, monomers possessing other acid groups such as sulfonic or phos phori c ac i d groups are al so useful . Representati ve m onomers i nc l ude ethylmethacrylate-2-sui fonic acid, 2-aerylamido-2~metbylpropane sulfonic acid, 2- methy l -2-propenoie acid ethyl-2-phosphate ester (HEMA-phosphate), ( I -phenylviny l )- phosphonic acid , or (2 -phenyiv inyl )-phosphonic aci d. Mi xtures of ac ids are al so practical.

[00231 For many appl ications, typical ly, the particle size of the binder resins would range from about 0. 1 to 1.0 microns. The Tg of some useful representative binder resins, of the present invention would typically be from about -60 to 1 00°C, Binder resins having a Tg less than about 20°C typical ly require less volatile organic compounds (solvents and coalescents) to form a smooth film compared to hi gher Tg polymers. In one useful embodiment the Tg would be les s than about 1 0°C , In another useful embodiment the Tg is less than about 1 °C. As used herein, the term "Tg" means polymer glass transition temperature.

[00241 Preparation of latex compositions is well known in the paint and coatings art. Any of the wel l-known free-rad ical emulsi on polymerization techniques used to formulate latex polymers can he used in the present invention. Such procedures include, for example, single feed, core-shell, and inverted core-shell procedures which produce homogeneous or structured particles,

[0025] In one useful embodiment the crossl inkabie binder resin would be obtained by polymerizing a monomer mixture of about 3 -25% by weight of a monomer having latent crossiinking functionality, 0.5 to about 15% of an acid functional monomer and about 60 to 98,5% other monomers, in another useful embodiment the monomer mixture would also comprise about 0.1 to about 10% of a wet adhesion promoting monomer. In another embodi ment, the monomer mixture wou ld comprise about 1 -25 % by wei ght of a monomer having latent crosslinking functionality, 0.5 to about 15% of an acid functional monomer, 0.1 to about 10% of a wet adhesion monomer, I to about 55 parts styrene, and the remainder selected from other copolymerizable monomers.

2. Crossiinkers

[0026] The crossiinker for reaction with the latent crosslinking functional ity need only be present in an amount necessary to achieve the desired degree of cure. For many applications, the crossiinker will typically be present at a level to provide at least 0.1 equivalent for each equivalent of latent crosslinking functionality.

[0027] In one of the embodiments of this invention, the crossiinker would be present at a level to provide between about 0.2 to about 2.0 equivalents for each equivalent of latent crosslinking functionality. In some useful embodiments the crossiinker will be present at a level to provide 0.4 to about 1 .2 equivalents for each equivalent of latent crosslinking functionality.

[0028] In another useful embodiment the crossiinker would be present at a level to provide about 0.4 to about 1 .0 equivalent for each equivalent of latent crosslinking functionality.

3. Monomer Modified Polyalkylene Terephthalate or Naphtha!ate Alkyds

[00291 The coatings of this invention also require the incorporation of an air-drying monomer modifi ed al kyd em ul si on resi n. For many embod i ments, level s of the additional resin between about 5% and about 60% by weight solids of the combined weight solids of the crosslinkable resin and the crossiinker and the alkyd resin are typical. For some embodiments the alkyd resin will be present at a level between about 1 5% and about 35% by weight solids of the total combined weight solids of the crosslinkable resin, crossiinker and alkyd resin.

[0030] One element of this invention relates to an aqueous alkyd dispersion derived from a polyalkylene terephthalate, or polyalkylene naphthalate, as a raw material for producing the resin. The process for making the dispersion includes an acidolysis reaction of a polyalkylene terephthalaie or polyalkylene naphthalate and the subsequent monomer modification of the resin followed by combining the modified resin with water in the presence of a base to provide water dispersibility. The production of such aikyds is taught, representatively in US patents 5,371,112 and 7,129,278 the teachings of which are hereby incorporated by reference,

|0031] One useful method to produce the polyalkylene terephihalate based alkyd is that taught in 7,129,278 and involves generally a process for forming a polymer which comprises reacting: a. a polymer formed as the reaction product of

(1) a mixture of compounds resulting from an acidolysis reaction of a

polyalkylene terephihalate (or naphthalate) with a member of the group consisting of acid- and anhydride-functional materials; and

(2) an alcohol, wherein the resulting reaction product has an acid value of less than 20; and h. an eihylenieaily-unsaturated monomer suitable for modifying the polymer to form a modified polymer resin; wherein the modified polymer resin has an acid value of less than 30, and wherein said modified polymer resin is then combined with water in the presence of a base to form the aqueous polymer composition.

|00S2] The monomer modified aikyd dispersion of this invention utilizes polyalkylene terephthalaie, or polyalkylene naphthalate, as the starting material for the production of the polymer. One useful polyalkylene terephihalate is polyethylene terephihalate (PET). Polyethylene naphthalate (PEN) can also be used. Other polyalkylene terephthalat.es are polypropylene terephthalaie, polybuiylene terephihalate, etc.

[0033J In the production of the alkyd, a polyalkylene terephihalate resin is first digested into lower molecular weight oligomeric units through an acidolysis reaction. The digestion product of the acidolysis reaction is then further reacted with a hydroxy- functional reactant to produce a resin which is further monomer-modified and dispersed into water. For purposes of this invention, the use of polyethylene terephthalate is described; however, i t should be recognized by those skil led i n the art that other po!yaikyiene terephthalates, or po!yalkylene naphthalaies, can be used similarly.

[00341 The actual source of PET usable herein is not of critical importance to this invention, "Virgin" PET, that is PET which is commercially produced specifically as a raw material, is acceptabie from a chemical standpoint for use herein. Likewise, recycled or reclai med PET is acceptabie from a chem ica l stand point . At the time of this application, there are advantages to the environment (reduction of solid waste) and to the economics of this process (recycled PET is much less expensive than virgin PET) by using recycled or reclaimed PET; and, there are no performance disadvantages to using recycled PET versus virgin PET. Typically, the sources for PET are many and varied. One source of either virgin or recycled PET is material from PET polymer manufacturers. Another source for PET can be post-industrial outlets. A further source is reclaimed PET, such as recycled PET beverage bottles. It should be appreciated that any source of PET is acceptable. Polyethylene naphthalate and polybuty!ene terephthalate are available similarly.

[0O3SJ The PET shoul d general ly be provi ded i n a comm i nuted form . It can be flaked, granulated, ground to a powder or peiletized. The only constraint placed on the PET at this point is that it is relatively pure; that is, there shouid not be a level of impurities above about one weight percent ( 3 wt %) nor shouid there be any appreciable level of impurities which are chemically reactive within this process. Poiyols also used in the manufacture of PET include diethylene glycols, triethylene glycols, neopentyl glycol, cyclohexane dimethanol, butanediols, and propanediols are used as polymer modifiers, and are acceptable as used in this invention.

[0036] PET is comprised of repeating units of ethylene glycol and terephthalic acid connected by ester linkages. Each repeating unit of PET has a weight average molecular weight of 192 with one equivalent of ethylene glycol and one equivalent of terephthalic acid. By reacting PET with an acid or anhydride functional material in an acidolysis reaction, it is possible to reduce the average chain length of the PET molecules. The chemistry of PET is such that an equilibrium exists between PET, water, ethylene glycol (EG), terephthaiic acid (TPA), and the acid used to reduce the chain length. This equilibrium makes it possible to substantially reverse the polymerization process and depoiymerize PET into its starting materials.

|0037] Suitable acid-functional materials for the acidolysis reaction include mono-functional acids such as benzoic, crotonic and sorbic acids; and acids having an acid functionality on average of at least two carboxylic acid groups, such as phthalic acid, isophthaiic acid, 1 ,4-cyclohexane dicarboxyiic acid, 1 ,3-cyclohexane dicarboxylic acid, succinic acid, adipic acid, azelaic acid, maleic acid, fumaric acid, trimeilitic acid, trimesic acid, naphthalene dicarboxylic acids, earboxy-terminated poiybutadiene, 4,4-dicarboxy diphenoxy ethane, and the hydroxy carboxylic acids of piralactone. Other suitable acids include the saturated acids such as butyric, caproic, caprylic, capric, lauric, myristic, palmitic, stearic, 12-hydroxystearic, arachidic, behenic and lignoceric acids; the unsaturated acids such as palmitoleie, oleic, ricinoleic, linoleic, linolenic, eieostearic, licaric, gadoleic and eracic acids; and the oils (and their fatty acids) such as canola, rapeseed, castor, dehydrated castor, coconut, coffee, com, cottonseed, fish, lard, linseed, oticica, palm kernel, peanut, perilla, safflower, soya, sunflower, tallow, tung, walnut, vernonia, tali and menhaden oils; and blends and mixtures of natural and synthetic oils and fatty acids, particularly those oils and fatty acids with high iodine numbers, In order to provide the alkyd with air drying capability it is convenient to utilize the drying oil and semi-drying oil fatty acids as at least some of the acid in the acidolysis reaction,

[0038] Representative anhydrides useful in the acidolysis include, acrylic anhydride, methacryiic anhydride, phthalic anhydride, 3-mtrophthaiic anhydride, 4- nitrophthalic anhydride, 3-flourophthalic anhydride, 4-chlorophthaiic anhydride, tetrachlorophthalic anhydride. tetrabromophthalic anhydride, tetrahydrophthali c anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, dodecenyisuccinic anhydride, octylsuccinic anhydride, maleic anhydride, dichioromaleic anhydride, glutaric anhydride, adipic anhydride, chlorendic anhydride, itaconic anhydride, citraconic anhydride, endo-meihyienetetrahydrophthalic anhydride, cyclohexane- 3,2-dicarboxyiic anhydride, 4-cyclohexene-l,2-dicarboxylic anhydride, 4- methy 1 -4-cyclohexene- 1 ,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, l,4-eyelohexadiene-3,2~diearboxylic anhydride, 3,3- eyelopentanedicarhoxyUc anhydride, diglycolic acid anhydride, benzophenone tetracarboxylic dianhydride and the like.

0031 Other useful anhydrides include those anhydrides having a free carboxyl group in addition to the anhydride group such as trimeliiiic anhydride, aconitic anhydride, 2,6,7-naphthalene tricarboxylic anhydride, 3,2,4-butane tricarboxylic anhydride, 3,3,4- c yclopentane tricarboxylic anhydride, and the like. It should be appreciated that other acids and anhydrides should be considered equivalents of those named herein.

[0040J The acid- or anhydride functional material will generally have a number average molecular weight below about 2000. Preferably the acid- or anhydride-functional material will have a number average molecular weight of below about 600. Typical number average molecular weights of these materials will range from about 96 to about 600.

[0041] Optionally, a catalyst can be used for the acidoiysis reaction. If used, suitable catalysts for acidoiysis of PET include the traditional transesterification catalysts including stannous octoate, calcium hydroxide, lithium hydroxide, barium hydroxide, sodium hydroxide, lithium methoxide, manganese acetate tetrahydrate, dibutyl tin oxide, butyl stannoic acid, and hydrated monobutyi tin oxide. If used, the catalyst should be present in an amount of from about 0.3 weight % to about 3.5 weight % based upon the total weight of the PET and acid-functional material.

[0042] When PET and an acid- or anhydride-functional material are reacted together in the presence of the catalyst (optional) and heat, the high molecular weight PET molecule is broken down into shorter chain fragments. This is accomplished through acidoiysis of the ester linkages and exchange by the acid with the terephthalic acid units of the PET molecule. This exchange continues to occur until a new equilibrium is established between the PET, the shorter chain length PET, the shorter chain length PET substituted with the acid, the acid-functional material and terephthalic acid.

[0043] Subsequent to acidoiysis, the remaining PET fragments and products in equilibrium therewith are predominantly acid-functional. As described further below, the acidoiysis reaction products can be further reacted with hydroxy-functionai materials and the like. The reaction can be carried out in the presence of a solvent for azeotroping of water or fusion in solventless systems.

|ΘΘ44] The products of the acidoiysis reaction are further reacted with hydroxyfunctional materials to produce a polyester product useful in coating compositions. Since the acidoiysis reaction products are predominantly acid- functional, they can be further reacted with alcohols including those taught below to obtain polymer compositions useful in coatings, By controlling the amounts and types of reaetants, as well as the length and temperature of the reaction, one can formulate low acid value systems from the acidoiysis reaction products. The products of such reactions include alkyds and polyesters which can be further modified and dispersed in water.

[0045] Generally, the alcohols used for reaction with the acidoiysis reaction product will have number average molecular weights of below about 4000, and typically, number average molecular weights will range from about 30 to about 4000, and especially 100 to about 600. Methods of preparing alcohols are well known in the art and the method of preparation of the alcohols is not critical to the practice of this invention.

[O046J Suitable alcohols include the CI-C22 linear and branched saturated and unsaturated alcohols including, for example, methanol, ethanol, propanol, butanol, hexanol, linoleyl alcohol, trimethy lolpropane diaily! ether, allyl alcohol, 2- mercaptoethanol and the like. Additionally, useful alcohols include the hydroxyfunctional polyethers, polyesters, polyurethanes, polycaprolactones, etc.

|0047] Saturated and unsaturated polyols include glycerol, castor oil, ethylene glycol, dipropylene glycol, 2,2,4~trimeihy3 1 ,3-pentanediol, neopentyl glycol, 1,2- propanedioi. 1 ,3-propanediol, 1 ,4-butanediol, 3 ,3-butanediol, 2,3-butanediol, 1.5- pentanediol, 1,6- hexanediol, 2,2-diniethyl-l,3-propanediol, dimethylol propionic acid, acetyienie diols, hydroxy-terminated polybutadiene, 1,4-cyciohexanedimethanol, 1,2- cyclohexanedi methanol, 3,3- c y c 1 o he x a n e d i meth ol, 1,4- bis(2- hydroxyethoxy)cyclohexane, trimethyiene glycol, tetra methylene glycol, pentamethylene glycol, hexamethylene glycol, deeamethy!ene glycol, diethyiene glycol, triethylene glycol, tetraethylene glycol, l,4-be3zenedimethanol, 1 ,4~benzenediethanoi, 2,4-dimethyl- 2-ethyiene3-sexane-l,3-diol_s 2-butene-l,4-diol, trimethyiolethane, trimethyloipropane, di-trimethylolpropane, trimethylolpropane monoallyl ether, trimethylolhexane, triethytolpropane, 1 ,2,4-butanetriol, glycerol, pentaerythrito!, dimethyiolpropane, dipentaerythritol, methyl propanediol, phenolic polyols, polypropylene ether glycols, polyethylene ether glycols etc,

[0048] Another useful class of hydroxy-funetionai materials are polymers such as those prepared by condensation polymerization reaction techniques or ring opening reactions of epoxies as are well known in the art.

[0049J As stated above, the acidolysis reaction products can be further reacted with alcohol to produce low acid value products. The term "low acid value products" is meant to be those compositions having acid values lower than about 20, in order to formulate an acidolysis reaction product to a low acid value of less than about 20, the following stoichiometric proportions of materials should be used. For each mole of repeating unit PET used, from about 1.5 to about 4.0 equivalents of acid/anhydride should be used in the acidolysis reaction, followed by further reaction with about 2.0 to about 4,0 equivalents of hydroxy-functionality. Preferably, the equivalents of acid/anhydride to repeating unit of PET should be about 2.0:1 to about 3.1:1 and the equivalents of OH to PET should be about 2.3:1 to about 3.7:1, Optionally, small amounts of amine or diamine can be substituted for some of the alcohols.

|0050] The initial acidolysis produced resin is then directly modified with unsaturated monomers, to produce the monomer modified water-reducible polymers utilized in this invention.

[0051] Direct monomer modification is typically conducted under conditions also well known in the art, including the procedures taught in U.S. Pat, Nos, 4,735,995 and 4,873,281. as well as by the procedures taught in the Examples below,

[0052] When monomericaiiy modifying the base polymers, the incorporation of a sufficient amount of acid-functional monomer material, with or without surfactants, will enable the final polymer products to be reducible in water or other aqueous systems when sufficiently neutralized as discussed below. |0OS3] Surfactants that can optionally be used for this invention include nonionic surfactants such as, but not limited to, nonylphenol ethoxylates (such as !GEPAL® CO-Series available from Rhodia, Cranberry. N.J,), octy phenol ethoxylates (such as 1GEPAL® CA-Series available from Rhodia, Cranberry, Ν,Ι,), polyether polyols (such as PLURONIC® or TETRON1C® available from BASF Corporation, Mt. Olive, N.J.), and acetyienic alcohols (such as SURFYNOUD available from Air Products, Allentown, Pa.). The surfactant, if present, is preferably about 1% to about 5% of the total weight of the polymer.

[Θ0541 Generally, amounts of acid-functional monomer materials greater than about 5.0% by weight of the total amount of monomer and other ethylenically unsaturated materials will result in a coating composition which is water reducible. Amounts less than the above will generally result in coatings which are not water reducible. Preferably, the monomer-modified base polymer of this invention has low volatile organic levels. More preferably, the volatile organic level of the monomer-modified base polymer is less than 10%.

[OOSSJ Suitable monomers for modifying the base polymer include the unsaturated acids, such as acrylic acid, meihacrylic acid, itaconic acid, crotonic acid, maleie acid, and half esters of maleic and fumaric acids, such as butyl hydrogen maieate and ethyl hydrogen fumarate, in which one carboxyl group is esterified with an alcohol. Examples of other ethylenically unsaturated monomers which can be used for the monomer modification of the acidolysis reaction product include the alkyl acrylat.es, such as methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, 2-ethylhexyl acrylate and isobornyl acrylate; the alkyl methacryiates, such as methyl methacrylate, butyl methaeryiaie, 2-ethylhexyl methacrylate, decyl methacrylate, iauryl methacrylate, acetoacetoxyethyl methacrylate, di methy!aminoethy 1 methacrylate, and ally! methacryiates and isobornyl methacrylate; hydroxyalkyl acrylates and methacryiates such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; acrylarnides and methacryiamides, diacetone acrylamide, and unsaturated nitriles such as acrylonitrile, methacrylonitrile, and ethacryionitrile. Other ethylenically unsaturated monomers (vinyl monomers) which can be used in addition to the acrylic monomers include: vinyl aromatic hydrocarbons (such as styrene, alpha-methyl styrene, and vinyl toluene); and vinyi aliphatic hydrocarbons (optionally substituted, for example, by halogen atoms) such as vinyl acetate, vinyl versatates, and vinyi chloride.

[0056] The monomer modification of the acidolysis reaction product generally can be conducted at from 80° C. to 160° C, and typically are conducted at from \0Q° C. to 150° C.

|O0S7] A polymerization initiator can be employed in the monomer modification stage. Examples of initiators include, but are not limited to: peroxyesters such as tertiary- butyl perbenzoate; azo compounds such as azobis(isobuiyronitrile); peroxides such as benzoyl peroxide and cumene hydroperoxide; peracetates such as tertiary butyl peracetate; percarbonaies such as ssopropyl percarbonate, peroxvcarbonates such as butyl isopropyl peroxycarbonate, and similar compounds. The quantity of initiator employed can be varied considerably; however, in most instances, it is desirable to utilize from about 0.1 to about 10 percent by weight based on the weight of eihylenicaliy unsaturated monomers used. Where desired, a chain modifying agent or chain transfer agent can be added to the polymerization mixture for control of the molecular weight of the resulting resin. Examples of such agents include the mercaptans, such as tertiary dodecyl mercaptan, dodecy l mercaptan, octyl mercaptan, and hexyl mercaptan, etc,

[00S8] The monomer modification reactions for preparing a resin composition of the invention can be carried out in the presence of an organic solvent, preferably only a limited amount of organic solvent being used so as to minimize the organic solvent content of the resulting product. In the preferred method of preparing the monomer modified resin of this invention, the base polymer serves as a polymerization medium for preparation of the modified polymer thereby significantly reducing the amount of organic solvent needed. The amount of monomeric materials used for modification is in the range of about 10% to about 80%, and more preferably, about 20% to about 60% based on total modified resin solids. For many applications, the modified polymer will have an acid value of less than 30. [0059] The monomer modified acid functional alkyd call be dispersed in water by admixing it with water in the presence of a suitable base. In one process, the monomer modified alkyd resin is initially liquefied by heating the resin to at least its melting point, and more preferably, to a temperature of at least 5° above its melting point so the polymer maintains a molten and flowable state, but below the decomposition temperature of the polymer, Typically, the modified polymer resin will melt in the temperature range from about 120° C. to about 140° C. A separate vessel of water, containing a base for neutralization of the carboxy!ic acids on the polymer, is heated to between 20° C. and 70° C. The base can be an amine compound or an alkali hydroxide. Water solubility or water dilutabiiity may be given to the resin by effecting neutral ization of acidic groups, such as carboxyl, with a basic material, such as monomethylamine, dimethyl amine, trimethylamine, monoethylamine, triethylamine, monoisopropylamine, diisopropylamine, d i ethyl ene tn arni ne, triethy leneteiram i ne, monoeihanol ami ne, di ethanol am ine, trieihanolamine, monoisopropanolamine, diisopropanoiamine, di methylethanolamine, morphoiine, methyl morpholine, piperazine, ammonia, sodium hydroxide, potassium hydroxide and the like, with or without surfactants. Typically enough base is added to neutralize some of the acid on the polymer. The water phase and the polymer phase are brought into contact with one another and, if desired, can be dispersed in a high shear mill or a homogenizer. The process can be continuous or in batch mode where the tank or mixing vessel contains the water phase. Once the polymer is dispersed in water, the pH is typically adj usted to 7.6-8,2 and the percent solids are adjusted to 35-55% by- weight. Preferably, the resulting polymer dispersion has a volatile organic level of less than 10% and an acid number of less than 30,

[0060] The coati ng compos ition of the present i nvention i s manufactured us ing techniques known to those skilled in the art of manufacturing paint. The coatings of this invention may also include conventional pigments and flattening agents as wel l as various additives. Examples of suitable inorganic flattening agents include silicates, such as talc and various forms of silica, such as amorphous, aerogel, diatomaceous, hydrogel and fumed silicas. Conventional pigments include titanium dioxide and other inorganic or organic pigments. The coatings of this invention also may incorporate one or more polymeric opacifying agents. The polymeric opacifiers are generally small particle size non-film forming polymerized beads which are insoluble in the coating in which they are dispersed. Typically the polymeric opacifying agents will replace some of the hiding pigments which would otherwise be incorporated into the coating. The beads may be solid or they may contain vesicles or dispersed pigments within the polymerized bead. Representative polymeric particles usefui as opacifying agents include beads of polystyrene, polyacrylic, polyethylene, polyamide, poly(vinylacetate ethylene), rnelamine formaldehyde, urea formaldehyde, polyester and polyurethane. Representative commercially available polymeric pigments are sold under the Ropaque, Dylex (polystyrene) and Pergopak (urea formaldehyde) trademarks. If polymeric opacifying agents are incorporated they typically will comprise between about 1% and about 85% by weight of the total amount of opacifying agents and pigments. Typical additives include dispersants, preservatives, ants foaming agents, thickeners, etc. The coatings of this invention can be applied to any substrate such as wood, wallboard, metal, etc. by any application method including spraying, brushing, roiling, etc. In one embodiment, the coatings are especially usefui as interior or exterior paints. Sf desired, the coatings of this invention can be formulated at very low levels of volatile organic compounds (VOC) presumably because the alkyd acts as a coalescing aid for the latex.

|0061] The following examples have been selected to illustrate specific embodiments and practices of advantage to a more complete understanding of the present invention. Unless otherwise indicated, parts means parts by weight and percent is percent by weight.

EXAMPLE 1 - Crosslinkable Binder Resin

[O062J A polymer was prepared as follows. A reaction vessel was charged with 1175.0 parts water and heated to about 85°C under a nitrogen blanket. A first mixture of 72.35 parts water, 4.35 parts anionic surfactant (Rhodafac® RE 610 from Rhodia Chemical), 3.12 parts ammonium persulfate and 0.68 parts 28% aqueous ammonia were added to the heated water, A first feed mixture of 264.90 parts water, 5.42 parts anionic surfactant (Rhodafac® RE 610 from Rhodia Chemical), 3.75 parts 28% aqueous ammonia, 13,60 parts methacrylic acid, 7.82 parts Sipomer Pam-200 phosphate monomer, 33.11 parts Rohamere 6844 (25% aqueous solution of N-(2- methacryloxyethyl)ethylene urea from Rohm Tech, Inc.), 33.60 parts T Mulz® (HEMA

IS phosphate ester from Harcros Chemical), 423 , 86 parts 2-ethyl hexyl acrylate, 272,41 parts styrene, and 23.33 parts diaeetone acrylamide was prepared. An initiator mixture of 1 .56 parts of ammonium persulfate and 79,97 parts water was prepared as well. The first feed mixture was fed into the reaction vessel over a period of about 90 minutes. The initiator mixture feed was begun at the same time as the first monomer mixture feed and was continued for the same time 90 minute time period.

[00631 Meanwhile, a second feed mixture of 264.90 parts water, 5.42 parts anionic surfactant (Rhodafac® RE 6 10 from Rhodia Chemi cal ), 3.75 parts 28% aqueous ammon ia, 13 ,60 parts methaeryl i e acid, 7, 82 parts Sipomer Pam-200 phosphate monomer, 31.1 1 parts Rohamere 6844, 239.32 parts methyl methacryiate, 19.99 parts 2- ethyl hexyl acrylate, 437.32 parts styrene, 13.60 parts T Mulz® (HEMA phosphate ester), and 23.33 parts diaeetone acrylamide was prepared. The second monomer mixture was then added into the reaction vessel over about 90 minutes while simultaneously adding a mixture of 1 .56 parts ammonium persulfate and 79,97 parts water. The reaction was al lowed to cool to about 65°C and a chase oxidizer mixture of 1 .68 parts t-butyi hydroperoxide in 31.99 parts water and a chase reducer mixture of 2.40 parts isoascorbie acid, 33.99 parts water, and 0,0.7 parts 28% aqueous ammonia was added over about 45 minutes. The reaction was then allowed to cool to about 33 °C and 17.98 parts 28% aqueous ammonia. 3 1 .30 parts Proxel GXL, 1 7.50 parts adipic dihydrazide and 89, 1 1 parts water were added to the reaction mixture. The water and adipic dihydrazide had been premixed and heated to about 65° until clear. The reaction was held at about 33°C for about 30 minutes after this addition.

EXAMPLE 2 - Initial PET Alkyd

[0064] An initial PET based alkyd was prepared by charging a reaction vessel with the following:

1 4.85 parts soya fatty acids (industrene 225 from BASF Corp.)

0,38 parts dibutyltin oxide

96.00 parts polyethylene terephthalate and heated to about 50G°F (260°C) until ali of the PET was melted. The mixture was allowed to eooi to about 360°F (182°C) and the following materials were added:

30.80 parts isophthalic acid

45.57 parts trimethylol ethane

8.00 parts methyl propyl ketone

[00651 The reaction mixture was heated to about 380^CF ( 1 93⁰C) unti l most of the water was removed and then gradually heated to about 460°F (238°C) and held at that temperature until an acid value of 7.0 was reached and the mixture allowed to cool.

EXAMPLE 3 - Acrylic Modified PET Aikyd

[ϋθδβ] A water reducibie acrylic modified PET alkyd was prepared by charging a reactor with the following:

78.41 parts PET alkyd of Example 2

3,92 parts alkali refined soybean oil

which was heated about 245°F (1 18°C) followed by the addition of;

0.37 parts dimethylbenzylamine

0.60 parts methaerylie anhydride

10.87 p arts n-buty 1 acetate

1.74 parts methyl propyl ketone and heated to 280°F (138°C) and held for 30 minutes.

[0067] A monomer mixture comprising:

4.74 parts acrylic acid

54.02 parts methyl methacry!ate

17.65 parts 2-ethyl hexyl acryiate and

an initiator mix of:

0,90 parts t-butyi perbenzoate 2,32 parts n-but l acetate

were added simultaneously to the reaction vessel over a 3 hour period and then heid for 30 minutes followed by the addition, over a 2 hour period, of a chase initiator mix of:

0.9 parts t-butyi perbenzoate

2,52 parts n-butyl acetate

0.49 parts cumene hydroperoxide

0.49 parts i-butyl hydroperoxide

[ΘΘ6§] The reaction mixture was heid for an additional 30 minutes and then disperse by addition of the reaction mixture into:

205.16 parts deionized water

4.40 parts dimethylethanolamine

0.71 parts defoamer

0.48 parts isoascorbic acid

to produce a final monomer modified PET alkyd dispersion with an acid value of 27.4.

A model paint formula can be prepared as follows:

Raw Material P rts by Weight

Crosslinkable resin of Example 3 6L0

053.0

Defoamer 001.0 9.7

Attapulgite Clay'

000.6

Hydroxyethyl Cellulose²

001.0 Be dsothiazolone Biocide

jVfin-U-Gei® 400 from Floridin Company

Ceilosi ,e® ER-52000 from Dow Chemical Dispersant³ 016.3

Emulsifying Agent⁴ ^

Defoamer⁵ 003,8 Microspheres⁶

2~(2~B uioxyethoxy)eihano3 _0Qg ^

Water 059,8

Coaleseent 12.0

Non-iosiie thickener⁸ 31.0 Titanium Dioxide Slurry⁹ ^

Fungicide'⁰ _{Q02 Q}

Surfactant" 003.0

Water 010.0

Defoamer'² 002.0

Diatomaceous earth 001.0

Aqueous Ammonia ^ g

Biocide do icil QK-20 000.3

Tamol® 165-A from Rohm and Haas

Triton® N~57 from Dow Chemical

5Byk-021

⁶ W4I0 ceramic microspheres from 3M

⁷ Optifiim enhancer 400 from Eastman

8AquaflowNHS-350

'CR8265

i^o IPBC-20 (20% solution of 3~iodopropynylbutylcarborsate from Arch Chemical) l^! Envirogem 360

1² HIMAR DFC-39 [0070] Whiie the invention has been shown and described with respect to particular embodiments thereof, those embodiments are for the purpose of illustration rather than limitation, and other variations and modifications of the specific embodiments herein described will be apparent to those skilled in the art, all within the intended spirit and scope of the invention. Accordingly, the invention is not to be iimited in scope and effect to the specific embodiments herein described, nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

Claims

WHAT IS CLAIMED IS:

Ail aqueous coating composition comprising:

0) a crossiinkable binder resin having iatent crossiinking functionality;

00 an effective crossiinking amount of a crosslinker for the binder resin; and

(iii) a water redueibie monomer modified alkyd obtained by the aeido!ysss of a poiyalkylene terephthaiate or poiyal kyiene napthanate and subsequent monomer modificati on to produce a polymer having an aci d val ue less than about 30,

2, The coating of claim 1 wherein the Iatent crossiinking functionality comprises carbonyi groups.

3. The coating of cl aim 2 wherei n the cross iinking agent i s sel ected from the group consi sting of di and poly amines, di and poly hydrazides, and di and poly hydrazines and mixtures thereof.

4. The coating of ciaim 1 wherein the crossiinkable binder resin is a latex resin.

5. The coating of claim 4 wherein the crossiinkable binder resin is the polymerized reaction product of a mixture of monomers comprising:

(i) about 1 to about 25% by weight of a monomer having iatent crossiinking

functionality;

(ii) about 0.5 to about 35% by weight of an acid functional monomer; (iii) about 60 to about 98,5% of at least one other copolymerizable monomer.

6. The coating of cl ai m 5 where i n the monomer having l atent cross l inki ng functionality has pendent carbonyl groups as reactive crosslinking sites,

7. The coating of claim 2 wherei n the crossl inker is selected from the group consisting of di and poly amines, di and poly hydrazides, and di and poly hydrazines,

8. The coating of claim 1 wherein the alkyd is present at a level of about 5 to about 65% based upon the total weight solids of alkyd and crosslinker and crosslinkable binder,

9. The coating of claim 1 wherei n the aikyd is obtained by the aci dolysi s of a polyalkylene terephthalate.

10. The coating of claim 9 wherein the polyalkylene terephthalate is polyethylene terephthalate

1 1 . The coati ng of clai m 1 wherein the alkyd has dry ing oi l or semi-drying oi l functionality.

12. A water reducible coating composition comprising:

(a) a crosslinkable binder resin which is the polymerized reaction product of a mixture of monomers comprising: (i) about 1 to about 25% by weight of a monomer having pendent

carbonyl latent erossHnking functionality;

(ϋ) about 0,5 to about 15% by weight of an acid functional monomer; and

(iii) about 60 to about 98.5% of at least one other copolymerizable

monomer; and

a crosslinker for the binder resin selected from the group consisting of di and poly amines, di and poly hydrazides, and di and poly hydrazines; and a water reducible monomer modified alkyd obtained by the acidolysis of a polyalkylene terephthalate or po!yalkyiene napthanate and subsequent monomer modification.