CA1146694A - Pigment dispersants for coating compositions - Google Patents

Abstract

Abstract of the Disclosure Pigment dispersants for use in coating compositions wherein the dispersant is the polymerization product of (i) an alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group, (ii) a hardening monomer selected from the group consisting of a styrene, methyl meth-acrylate, ethyl methacrylate and mixtures thereof, (iii) an ethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer having n double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride, (iv) a monomer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or an epoxide, and (v) a compound providing an amine or amine salt functional moiety. The dispersants are useful for dispersing pigments in coating compositions containing a wide variety of film-forming resins.

Description

1~46f~4 PIGMENT DISPERSANTS FOK COATING CO POSIT[)N5 Background of the Invention The subject invention relates to (1) pigment dispersants,

(2) their use in pigment dispersions containing pigment and liquid carrier and (3) coating compositions containing the pigment dispersions. The dispersants are useful in the manufacture of a wide variety of pigmented resin-containing coating compositions.
Pigmented coating compositions are useful for their aesthetic as well as protective features. Such compositions contain a film-forming resin and a pigment dispersed in a liquid carrier. It is important that the pigment be satisfactorily dispersed throughout any film which results from the application of the coating composition. It is therefore desirable that the pigment be well dispersed throughout the liquid coating composition.
Typically, the pigment to be used in a coating composition is first dis-persed with only a portion of the total film-forming resin of which the coating composition is comprised together with appropriate liquid carriers and addi~ives. The resulting dispersion is the;l mixed with the remainder of the film-forming re.sin and any other necessary components to produce the coating composition. Most pigment dispersants are very specific in their performance and are compatible with only a small number of the diverse solvents and film-forming resins used in coating compositions. For example, in the case of an acrylic resin based coating composition, the pigment will be first dispersed with a portion of the acrylic resin in the presence of an organic solvent. The resultant product is then further diluted with the remainder of the acrylic resin and any other necessary components -1- . ~

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forming a part of the coating composition. The final color oE the coating composition is normally adjusted by small further additions of pigment dispersions containing the same or similar film-forming resins just prior to use. This further addition is normally referred to as "tinting".
A number of different film-forming resins are used in the manufacture of different coating compositions. Accordingly, heretofore it has been necessary to predisperse pigments with a portion of the film-forming resin or a resin compatible therewith, which is appropri-ate to each type of coatin~ composition. That is, even though the pigmentation of two coating compositions containing different film-forming resins may be identical, it has been necessary to disperse each pigment or mixture of pigments separately with the appropriate film-forming resin. This is necessary so as to avoid any problems of incompat-ibility in the final coating composition. In a similar manner any tinting operation requires the use of dispersants which are compatible with the film-forming resin being used.
One solution to the aforementioned well~known problem has been the development of so called "multi-purpose" pigment grinding vehicles.
The polymeric dispersants contained in the multi-purpose pigment grinding vehicles are compatible with a wide range of film-forming resins and solvents. It can readily be recognized that a pigment grinding vehicle which can be used in many coating systems would be of significant savings to the coatings industry. Thus, one set of pigment dispersions could be used with a wide variety of coating compositions.
There have now been found dispersants based on the polymer-ization products of specific monomeric units which are capable of acting as multi-purpose dispersants. Such dispersants are useful for dispersing pigments and which can then be used in resin-containing coating compositions.

1~9L6~4 As used herein all percentages arld ratios are by weight unless otherwise indicated.

Summary of the Invent;on .. . .
A dispersant compatible with a variety of film-forming resins is the polymerization product of (i) from about 20 percent to about 85 percent of an alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group, (ii) from about 5 percent to about 60 percent of a hardening monomer selected from the group consisting of a styrene, methyl methacrylate, ethyl methacrylate and mixtures thereof, (iii) from about 1 percent to about 25 percent of an ethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride, (iv) from about 1 percent to about 25 percent of a monomer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or epoxide, and (v) from about 0.1 percent to abou~ 15 percent of a compound providing an amine or amine salt functional moiety; and wherein said dispersant has a weight average molecular weight as determined by gel permeation chromatography, using a polystyrene standard of from about 1,000 to about 10,000.
The above-described dispersants are especially adap~ed for dispersing pigments to be used in coating compositions wherein the film-forming resin is an epoxy, vinyl, alkyd, polyester, acrylic, aminoplast, phenolplast, cellulose derivative, amide, or urethane resin or mixtures thereof.

~46694 Detailed Description of the Invention _ The invention herein described relates to (I) dispersants, (2) pigment dispersions containing the dispersant, pigment and liquid carrier and (3) coating compositions containing the dispersant, pig-ment, film-forming resin and a liquid carrier.

Dispersants The dispersants described herein are the pclymerization product of an alkyl methacrylate, a hardening monomer, an ethylenically unsaturated carboxylic acid or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride, a monomer having or providing a carbonyl group with a double bond alpha-beta to the carbonyl group and at least one hydroxyl group and a compound providing an amine or amine salt functional moiety. Each of the individual components used in forming the polymer is described in the succeeding paragraphs. The percentages of the individual components are given on the basis of the non-volatile components.
The alkyl methacrylate is used in the formation of the polymer at a level of from about 20 percent to about 85 perceut, preferably from about 40 percent to about 80 percent, and more preferably from about 60 percent to about 80 percent of the reaction mixture. The alkyl methacrylates contain from 3 to 8 carbon atoms in the alkyl chain. Examples of satis-factory alkyl methacrylates include isopropyl mèthacrylate, butyl meth-acrylate, isobutyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate and octyl methacrylate. The branched chain methacrylates are preferred with isobutyl methacrylate being the most preferred alkyl methacrylate.

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A hardening monotner seLected from the group consisting of a styrene, metilyl methacrylate, e~hyl methacrylate and mixtures thereof is used in formation of the herein described polymer at a level of from about 5 percent to about 60 percent, preferably from about 15 percent to about 40 percent, more preferably from about 20 percent to about 35 percent.
A styrene, as used herein, is intended to include styrene and the substi-tuted styrenes, e.g., alpha-methyl styrene, vinyl toluene, chlorostyrene, and tert-butylstyrene. Styrene and methyl methacrylate are the preferred hardenîng monomers.
From about 1 percent to about 25 percent, preferably from about 1 percent to about 20 percent, more preferably from about 1 percent to about 15 percent, of the reaction mixture comprises the ethylenically unsaturated carboxylic acid or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride. The ethylenically unsaturated carboxylic acid is selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic ac;d, fumaric acid and mixtures thereof. Acrylic acid and methacrylic acid are ~he preferred ethylenically unsaturated carboxylic ac;ds.

Instead of polymerizing the ethylenically unsaturated carboxylic acid into the polymer, other monomers can be used which when further reacted provide the carboxyl functionality. Thus, alkyl acrylates such as methyl or ethyl acrylate can be polymerized into the polymer and thereafter hydrolyzed~ Another technique of introducing the carboxyl functionality to the polymer is to use an unsaturated anhydride, e.g., maleic anhydride or substituted maleic anhydride, in the initial polymeri~ation reaction followed by the opening of the anhydride with (l) water to yield a diacid, ~9,669~

(2) an alcohol to yield an es~er acid or (3) an amine to yiel(l an amide acid. The alcohol and amine are alkyl, aryl or cycloal;phatic in nsture and include methyl alcohol, ethyl alcohol, 2-ethylhexyl alcohol, the phenols and napthols, cyclohexanol, furfuryl alcohol, ethyl amine, hexyl amine, diethyl amine, dibutyl amine, aniline, alkyl substituted anilines, piperidine and morpholine. Still another method of providing the carboxyl functionality in the polymer is to use a hydroxyl or amine-containing monomer in preparing the polymer and thereafter react it with an anhydride.
The reaction of the hydroxyl group with an anhydride gives an ester acid while the reaction of the amine group with an anhydride gives an amide -acid. ~onomers that provide the hydroxyl groups in the polymer include the hydroxyalkyl acrylates and methacrylates, e.g., hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxyethyl methacrylate. Monomers that provide the amine groups include tert-butylaminoethyl methacrylate and aziridine reaction products which furnish amine functionality pendent from the polymer.
The polymer reaction mixture also contains from about 1 percent to about 25 percent of a monomer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or an epoxide. The preferred level of this component ranges from about 1 percent to about 15 percent, with the more preferred level being from about one percent to about 10 percent. Examples of monomers having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group are the monohydroxy alkyl acrylates, alkyl methacrylates and alkyl crotonates and the mono- and dihydroxy alkyl fumarates, itaconates, and maleates. Preferred are the hydroxyl-containing alkyl acrylates and methacrylates with the alkyl group containing from 2 1:~4t~6~

carbon ato,~s to ~0 carbon atoms, preferably from 2 carbon atoms to 6 carl~on atoms. Suitable hydroxyL-containing monomers ;nclude hydroxyethyl acrylate, hydroxypropyl acrylates, hydroxyethyl methacrylate and hydroxypropyl methacrylate, with hydroxyethyl acrylate being preferred.
Examples of monomers which provide the carbonyl group with the alpha-beta unsaturation and at least one hydroxyl group when reacted with an acid are the glycidyl acrylates and glycidyl methacrylates. The glycidyl acrylate or methacrylate is reacted with the other described monomers to form a polymerization product, which is then reacted with an acid such as acetic acid, lauric acid, ben~oic acid, or nicotinic acid to open the epoxide ring. It will be recognized that a nitrogen-containing acid used to open the epoxide ring can also be used to introduce the amine functional moiety (as below discussed) to the dispersant. The resultant polymeri~ation product contains a carbonyl group with alpha-beta unsatura-tion to a carbonyl group and at least one hydroxyl group.
Monomers which provide a carbonyl group with the alpha-beta unsaturation and at least one hydroxyl group when reacted with an epoxide are acryl;c and methacrylic acid. I~us, a polymer which is formed as described herein using acrylic or methacrylic acid as monomer (iv) is formed and then reacted with an epoxide. Suitable epoxides include styrene oxide, glycidol, ethylene oxide, propylene oxide 1,2- and 2,3-butylene oxide, butyl glycidyl ether, phenyl glycidyl ether and a glycidyl ester of a saturated Cg_ll tertiary monocarboxylic acid. The reaction of the acrylic or methacrylic units of the interpolymer with the epoxide results in the formation on the polymer of a carbonyl group with the alpha-beta unsaturation and at least one hydroxyl group.
A fifth component used in the formation of the polymer is a compound capable of providing an amine or amine salt functional moiety.

This compotlnd is used at a leveJ rnnging ~rom about 0.1 percent to about 15 percent, preferably from about 0.5 percent to about 3 percent of the polymer reaction mixture. The amine salt functional moiety can be provided by an aliphatic or alicyclic amine which forms a salt with the carboxyl moiety of the interpolymer compound. Examples thereof include oleylamine, cyclohexylamine, dimethylbenzylamine, dimethylethanolamine, diethylethanolamine and stearylamine. One source of amine functional moieties is provided by an acrylic or methacrylic compound containing amino groups, e.g., dimethylaminoethyl methacrylate, ethyl-, propyl- and t-boutyl-aminoethyl acrylate and t-butylaminoethyl methacrylate or 2- and 4-vinyl pyridine. Such compounds are polymerized into the backbone of the inter-polymer. Additionally, the amine functional moiety can be provided by the inclusion of a nitrogen~containing ring opening compound in the polymerization reaction mixture. Such compounds are represented by the following formula:

Rl - C - (C~ ~ C - Rs N

where Rl, R2, R4, Rs, and R6 are each hydrogen; alkyl having up to 20 carbon atoms, e.g., methyl, ethyl or propyl; aryl, e.g., phenyl;
alkaryl, e.g., tolyl or xylyl; or aralkyl, e.g., benzyl or phenethyl. R3 is hydrogen or a lower alkyl having from 1 to 6 carbon atoms and n is O or 1. Examples of suitable compounds useful herein include: ethylenimine (aziridine), 1,2-propylenimine, 1,3-propylenimine, 1,2~-dodecylenimine, l,l-dimethyl ethylenimine, phenyl ethylenimine, benzyl ethylenimine, tolyl ethylenimine, hydroxyethyl ethylenimine, aminoethyl ethylenimine, 2-methyl propylcnimine, N-ethyl ethylenimine, N-phenyl ethylenimine and ~-tolyl ethylenimine. The preferred aziridine compounds are the alkylenimines havi~g 2 to 4 carbon atoms, especially ethylenimine and 1,2-propylenimine.
The polymers are made by conventional solution polymerization of the aforedescribed individual components in an inert organic solvent. A so called "one shot" procedure can be used wherein each of the individual monomers is present at the start of the polymerization reaction. The reaction i~ conducted at a temperature of from about 80C. to ab~ut 160C., preferably from about 120~C. to about 145C. for from about 45 -minutes to about 6 hours, preferably about 90 minutes to about 2 1/2 houra. Example~ oE suitable inert organic ~olvent~ include the following:
eeher-type nlcohoLs, e.g., ethylene glycol monobutyl ether, ethylene glycol monoethyl ether and propylene glycol monobutyl ether, ethanol, propanol, i~opropanol and butanol. The polymerization is carried out in the presence of a vinyl polymerization catalyst. Preferred catalysts are the azo compounds, e.g., alpha, alpha'-azobis(i~obutyronitrile), tertiary butyl perbenzoate, tertiary butyl pivalate, isopropyl percarbonate and benzoyl peroxide. It should be recognized that the resultant reaction product can be isolated or have a part of the solvent removed. Preferably, however, the solvent is retained for convenience in later forming the pigment dispersion and the coating composition containing same.
The resultant polymers have a weight average molecular weight determined by gel permeation chromatography, using a polystyrene standard, of from about l,OO0 to about lO,OOO, preferably from about 2,000 to about 6,000. A molecular weight below about l,OOO i9 to be avoided inasmuch as the resultant polymer ie too bFIttle and wi11 not pooe-e~ the desired set g _ .

... ~ , , 6~4 of properties. Similarly, a molecular weight above about 10,000 indicates formation of a product which does not possess the desired set of dispersing properties or appropriate compatibility. ~s above discussed, the molecular weight of the po]ymer is determined by gel permeation chromatography using a polystyrene standard. Determination of molecular weights of polymers in this manner is well known.
The mixture of monomers used to make the above-described dis-persant can additionally consist essentially of a monomer selected from the group consisting of alkyl esters of acrylic acid wherein the alkyl group contains from 3 to 20 carbon atoms, alkyl esters of methacrylic acid wherein the alkyl group contains from 9 to 20 carbon atoms and mixtures thereof. The level of this monomer ranges from about 1 percent to about 30 percent, preferably from about 5 percent to about 20 percent of the reaction mixture. The inclusion of this monomer is to maintain flexibility or aid in compatibility when so desired.

Pigment Dispersion Compositions ~le aforedescribed dispersants permit the prior preparation of dispersions of pigments or pigment mixtures which are subsequently used in coating compositions. Each of the dispersions can be employed for the direct pigmentation of coating compositions. The pigment dispersions can be prepared at any convenient time and stored for future use.
The pigment dispersions of this invention consist essentially of from about 1 percent to about 50 percent, preferably from about 3 percent to about 30 percent of the aforedescribed dispersant, from about 10 percent to about 90 percent, preferably about 15 percent to about 80 percent of a pigment and the balance a liquid carrier. Pigments useful 6~

herein include those conventionalLy used ;n the coatings i~dustry. ~xamples of suitable pigments include the iron oxides, lead chromates, silico-chromate, stronium chromate, lead carbonate, lead sulfate, barium car-bonate, china clay, calcium carbonate, aluminum silica, zinc oxide, zinc sulfide, æirconium oxide, antimony oxide, titanium dioxide, chrome green, chrome yellow, thio-indigo red, phthalo blue, phthalo green, cobalt blue, cadmium yellow, cadmium red, toluidene red, graphite, carbon black, metallic aluminum, and metallic æinc.
The solvents used in the pigment dispersions are conveniently the solvents used in the reaction of the monomers to form the inter-polymer. Ho~ever, other solvents can be added, such as xylene or mineral spirits.
The pigment dispersions can contain other additives commonly used in pigment dispersions, for example, plasticizers, wetting agents, defoamers, diluents and fLow control agents.
Pigment dispersions are made by grinding or dispersing the pigment into the dispersant. The grinding is usually accomplished by the use of ball mills, sand mills, Cowles dissolvers, continuous attritors and the like, until the pigment has been reduced to the desired size.
After grinding, the particle size of the pigment is in the range of about 10 microns or less.

Coating Composition The pigment dispersions described above are added to coating compositions either by the manufacturer and/or just prior to use by the consumer as a tinting composition. The pigment dispersions are compatible with a wide variety of fiim-forming resins and do not adversely affect the ~66~flt properties of a dried film made from the coating colllpositions. In particula~
films made ~rom the co~positions of this invention have good color develop-ment and intercoat adhesion, i.e., have the ability to adhere ~o a previously formed film. This latter feature is difficult to attain and represents an especially important feature possessed by the compositions herein.
Useful coating compositions consis~ essentially of from about 25 percent to about 98 percent, preferably about 30 percent to about 80 percent of the film-formiDg resin, from about 1 percent to about 70 percent, preferably about 20 percent to about 60 percent of the pigment, from about 1 percent to about 50 percent, preferably about 2 percent to about 30 percent of the dispersant and the balance liquid carrier. Suitable film-forming resins used in conjunction with the pigment dispersions are described in the succeeding paragraphs. The film-forming resin can be an epoxy, vinyl, alkyd, polyester, acrylic, aminoplast, phenolplast, cellulose derivative, amide or urethane resin or mixtures thereof. Copolymers derived from such resins are also useful herein.
The epoxide resins used as a film-forming resin in the coating compositions are those compounds having a 1,2-epoxy group, i.e., -CH - CH-present in the molecule. Polyepoxides contain more than one 1,2-epoxy group per molecule. In general, the epoxide equivalent weight will range from about 140 to about 4,000. These polyepoxides are saturated or unsat-urated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic.

They can contain substituents such as halogen, hydroxyl and ether groups.

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One usef~l class of polvepoxides compriqes the epoxy polyethers obtained by reacting an epihalohydrin (such as epichlorohydrin or epibromo-hyclrin) with a polyphenol in the presence of an alkali. Suitable poly-phenols include resorcinol, catechol, hydroquinone, bis(4-hydroxyphenyl)-2, 2-propane, i.e.~ bisphenol A; bis(4-hydroxyphenyl)-1,1-isobutane;4,4-di- -hydroxybenæophenone; bis(~-hydroxyphenyl)-l,l-ethane; bis(2-nydroxy-naphenyl)-methane; and 1,5-hydroxynaphthalene. One very common polyepoxide is a polyglycidyl ether of a polyphenol, such as bisphenol A.
Another class of epoxy resins are the polyglycidyl ethers of polyhydric alcohols. These compounds may be derived from such polyhydric alcohols as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol, trimethylolpropane, and bis(4-hydroxycyclohexyl)-2,2-propane.
Another slass of epoxide resins are the polyglycidyl esters of polycarboxylic acids. These compounds are produced by the reaction of epichlorohydrin or a similar epoxy compound with an aliphatic or aromatic polycarboxylic acid such as oxalic acid, succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid and dimerized linoleic acid.
Still another class of polyepoxides are derived from the epoxida-tion of an olefinically unsaturated alicyclic compound. These polyepoxides are non-phenolic and are obtained by epoxidation of alicyclic olefins, for example, by oxygen and selected metal catalysts, by perbenzoic acid, by acid-aldehyde monoperacetate or by peracetic acid. Among such polyepoxides are the epoxy alicyclic ethers and esters well known in the art.

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Useful polyepoxides also include those containin~ oxyalkylene groups in the epoxy molecule. Such oxyalkylene groups have the general formula:
__ _ , ----- O tCH2-C ¦-------m n where R is hydrogen or alkyl, preferably a lower alkyl having from 1 to 6 carbon atoms, m is 1 to 4 and n is 2 to 50. Such groups are pendant to the main molecular chain of the polyepoxide or are part of the main chain itself. The proportion of oxyalkylene groups in the polyepox;de depends upon many factors, including the chain length of the oxyalkylene group, the nature of the epoxy and the degree of water solubility desired.
Another class of polyepoxides consists of the epoxy novolac resins. These resins are obtained by reacting an epihalohydrin with the condensation product of aldehyde and monohydric or polyhydric phenols.
A typical example is the reaction product of epichlorohydrin with a phenol-formaldehyde condensate.
Any well-known curing reactant for the above-described epoxy resins is normally included in the coating composition. It is well known chemicals and resins containing functional groups with active hydrogen groups are useful as curing agents for the epoxy resins. Generally, the curing agents cause polymerization by cross-linking of the epoxy molecules. Amine and polyamide catalysts are especially preferred curing agents.

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Vinyl resins used in the coating compositions are derived rom monomers containing a carbon to carbon double bond. These monnmers polymerize by linear addition to form long chain molecules. Generally, the polymeric resins have the structure:

rH R H R ~ R---- C -- C -- C -- C -- C -- C --I I I I I I
H Rl H Rl H Rl n where R and Rl represent various pendant groups such as hydrogen, chlorine, acetate, benzene and toluene. The vinyl resins are commcnly derived from the monomers vinyl chloride, vinylidene chloride, vinyl acetate, the vinyl acetals, styrene, acrylonitrile and mixtures thereof. The vinyl polymers and copolymers range from about 100 to 10,000 carbon atoms in chain length and can be formed by bulk, solvent, suspension or emulsion polymerization.
Copolymers derived from mixtures of any of the aforedescribed vinyl monomers either with themselves or with other commonly used polymer-izable monomers are used herein. Such copolymers possess a wide range of properties and can be formulated to fit individual needs.
One class of resins especially useful herein are the alkyd resins. Such resins are polyesters of polyhydroxyl alcohols and poly-carboxyl acids chemically combined with various drying, semi-drying and non-drying oils in different proportions. Thus, for example, the alkyd resins are made from polycarboxylic acids such as phthalic acid, maleic acid, fumaric acid, isophthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid as well as from anhydrides of such acids, where ~466~A~

they exist. The polyhydric alcohols which are reacted with the polycar-boxylic acid include glycerol, trimethyloLethane, trimethylolpropane, pentaerythritol, sorbitol, mannitol, ethylene glycol, diethylene glycol and 2,3-butylene glycol.
The alkyd resins are produced by reacting the polycarboxylic acid and the polyhydric alcohol together with a drying, semi-drying or non-drying oil in proportions depending upon the properties desired.
The oils are coupled into the resin molecule by esterification during the manufacturing and become an integral part of the polymer. The oil is fully saturated or predominately unsaturated. The fully saturated oils tend to give a plasticizing effect to the alkyd, whereas the pre-dominately unsaturated oils tend to cross-link and dry rapidly with oxidation to give more tough and durable alkyd resins. Suitable oils include coconut oil, fish oil, linseed oil, tung oil, castor oil, cottonseed oil, safflower oil, soybean oil, and tall oil. Various pro-portions of the polycarboxylic acid, polyhydric alcohol and oil are used to obtain alkyd resins of various properties.
Also useful herein are polyester type resins. As convention-ally used and as used herein, the term "polyester" is applied to resins which contain no oil or fatty acid modification. That is, while the above-described alkyd resins are in the broadest sense polyester type resins, they are oil-modified and thus not generally considered a polyester resin. The polyesters are of two kinds. The more common are the unsatur-ated polyesters derived from unsaturated polyfunctional acids and polyhydric alcohol. These polyesters are essentially linear in structure. Male;c acid and fumaric acid are the usual unsaturated acid componen.s. Co~monly used polyhydric alcohols are ethylene glycol, propylene glycol, diethylene ~ 16 -6~94 glycol, dipropylene glycol, butylene glycoll glycerol, trimethylol propar~e, pentaerythritol and sorbitol. Oftentimes a saturated acid will be included in the reaction to provide desirable properties. Examples of saturated acids include phthalic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid and the anhydrides thereof where they exist. The saturated polyesters are derived from saturated or aromatic polyfunctional acids, preferably dicarboxylic acids, and mixtures of polyhydric alcohols having an average hydroxyl functionality greater than 2.
Useful acrylic resins are the polymerized ester derivatives of acrylic acid and methacrylic acid. The resins contain the units fH3 (-CH2 - CH-)n and (-CH2 - C-)n 0=C-0-R O=C-0-R

respectively. The esters are formed by the reaction of acrylic or meth-acrylic acid with suitable alcohols, e.g., methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol and 2-ethylhexyl alcohol. Generally speaking, the larger the alcohol portion of the ester, the softer and more flexible the resultant resin. Also, generally speaking, the methacrylate esters form harder films than the corresponding acrylic esters. Monomers such as styrene, vinyl toluene, vinyl chloride and vinylidine chloride may be reacted with the acrylic and methacrylic esters so as to produce resins with excellent properties.
Thermosetting acrylic resins are normally low molecular weight copolymers made from 2 and sometimes 3 monomers. One of the monomers is an acrylic compound containing pendant reactive groups such as carboxyl, ~6~

hydroxyl or amide. Another i9 an acrylic ester. The third monomer is usually a .styrene type monomer such as styrene itself, vinyl toluene, methyl styrene or ethyl styrene. The proportions of the three co-nponents in the polymerization procedure are varied depending on the products in which the copolymer will be used.
Another class oE film-forming resins useful in the coating compositions herein is the amino resins commonly referred to as aminoplasts.
The amino resins are made by the reaction of an amine with an aldehyde.
The more important and preferred amines are urea and melamine. The aldehyde component comprises from 1 to 4 carbon atoms, with formaldehyde being the preferred aldehyde. Films of varying properties can be obtained by changing the proportions of the amine and aldehyde and by adding various chemically-reactive materials during the resin formation. Oftentimes, a lower alcohol, especially butanol, is added during the resin formation to impart desirable properties to the amino resin.
The phenolic resins commonly referred to as phenoplasts are also useful film-formers in the context of the subject invention. The phenolic resins are obtained by the condensation of phenol or substi-tuted phenols with aldehydes. The monohydric phenols such as phenol, cresol and xylanol are the most important since they are readily available and relatively ine~pensive. Phenol is the most preferred monohydric phenol. Polyhydric phenols such as resorcinol can also be used herein.
Formaldehyde is the preferred aldehyde used in the production of the phenolic resins. Other aldehydes which are also useful include acetaldehyde, butyraldehyde and furfuraldehyde. The preferred phenolic resin is produced by the condensation of phenol and formaldehyde.

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Different celluLose derivative~s useful herein incLude nitro-ceLLulose, cellulose acetate, cellulose acetate butyrate and ethyl cellulose.
These film-~ormîng materials are well known and are commercially ava;lable in varying degrees of substitution and molecular weight. Nitrocellulose is the preferred cellulose derivative.
Amide resins found to be useful include those polymers made by condensing a diamine with a dibasic acid. They are characterized by recurring amide groups, -CONH-, as an integral part of the main polymer chain. Examples of diamines used in producing the polyamide resins include ethylenediamine, diethylenetriamine and hexamethylenediamine. The carboxylic acids are the preferred dibasic acids and include adipic acid, sebacic acid, succinic acid, glutaric acid and azelaic acid.
Another class of film-formers used in the invention herein are the urethane resins. These are synthetic polymers that may be either thermoplastic or thermosetting. The basic polymeric unit is RNHCOOR. The R groups can be the same or diEferent and can contain other reactive groups, for example, a second -NCO group, a second -OH group, etc. Typi-cally, a polyhydric alcohol is reacted ~ith a polyisocyanate to produce the urethane resin. Useful polyhydric alcohols include ethylene glycol, propylene glycol, butylene glycol, glycerol~ trimethylolpropane and hexane triol. Many variations are possible.
The urethane coating can be made from a one-pack or two-pack system. The one-pack urethane contains either an isocyanate prepoly-mer or a blocked ;socyanate. The prepolymers are prepared by the re-action of excess diisocyanate with a polyhydric alcohol. Blocked iso- -cyanates contain no free isocyanate groups and are relatively inactive 11~66~

at room temperature. At elevated temperatures, the compounds dissociflte and undergo reactions typical of isocyanates. Typical blocking agents are phenols, thiols, tertiary alcohols and secondary aromatic amines. In a two-pack coating system, typically a polyester polyol and an isocyanate (or isocyanate prepolymer for safety reasons) are mixed at the time of appli- -cation and applied immediately.
It will be recognized that a grea~ many copolymers based upon the above~described monomers are possible. Such copolymers possess a wide range of properties and can be formulated to fit individual needs.
The copolymers are contemplated herein as being ùseful film-forming resins compatible with the resin dispersants of this invention.
The balance of the compositions comprises a liquid carrier material. Many different organic solvents are suitable, examples of which include hydrocarbons and halogenated hydrocarbons such as toluene, xylene, mineral spirits, n-hexane, cyclohexane, chlorobenzene, and perchloroethylene.
Additives commonly used in coating compositions can be used herein also. Such additives include plasticizers, fillers, surfactants and stabilizers.
The coating compositions are applied by conventional coating techniques onto a variety of substrates. Thus, the compositions can be applied by spraying, brushing, dipping, flow coating and roll coat-ing. Substrates that can be coated include wood, metals, glass, plastics and wallboard.
The examples which follow are illustrative of the invention.
All molecular weights given are determined by gel permeation chromatography using a polystyrene standard.

~L4~

EXAMPLI~ I
Isobutyl methacrylate ]117 grams Methyl methacrylate 466.5 grams Acrylic acid 42.1 grams Dimethyloctadecylamine 37.2 grams ~Iydroxyethyl acrylate 42.1 grams 2-Mercaptoethanol 25 grams Tertiary butyl perbenzoate (TBPB) 116.8 grams ~thylene glycol monobutyl ether 1525.7 grams Denatured ethyl alcohol 30 grams A reaction vessel is set up equipped with heating means, stirring means, means for maintaining a nitrogen blanket throughout the reaction and refluxing means. ~ solvent blend of 1346 grams ethylene glycol monobutyl ether and the denatured alcohol is heated to reflux under a nitrogen blanket. At the reflux temperature a stream of the isobutyl methacrylate, methyl methacrylate, hydroxyethyl acrylate, acrylic acid and 2-mercapto-ethanol and ~mother stream of 83.4 grams of TBPB and 118 grams of ethylene glycol monobutyl ether are added to the reaction mixture over a period of two hours. This mixture is held at reflux for one hour after .he separate streams have been charged to the reaction vessel. Thereafter, the reaction is cooled to 120C. at which time 33.4 grams of TBPB and 61.7 grams of ethylene glycol monobutyl ether are added over a period of one hour.
This mixture is then held one hour at 120C. The resultant reaction mixture contains 50 percent solids and has a Gardner-~oldt viscosity of H-I. The amine functional salt of the resin dispersant is formed by adding the dimethyloctadecyl amine to the reaction mixture.
The dispersant has a weight average molecular weight of 2200.

1~4ti6~4 _~MP~E II
The following components are utili~ed in forming a resin dispersant:
Isobutyl methacrylate1278.9 grams Methyl methacrylate 302.9 gram~
Methacrylic acid 42.1 grams Hydroxyethyl acrylate 42.1 grams Dimethylaminoethyl methacrylate 16.8 grams 2-Mercaptoethanol 50.5 grams Ethylene glycol monobutyl ether 1573.3 grams Denatured ethyl alcohol33.7 grams Tertiary butyl perbenzoate (TBPB) 84.1 grams A reaction vessel is set up equipped with heating means, stirring means, means for maintaining a nitrogen blanket throughout the reaction and refluxing means. A solvent blend of 1346.1 grams of the ethylene glycol monobutyl ether and the denatured ethyl alcohol is heated to reflux under a nitrogen blanket. At the reflux temperature a stream of the methacrylic acid, hydroxyethyl acrylate, isobutyl meth-acrylate, methyl methacrylate, dimethylaminoethyl methacrylate, 2-mercapto-ethanol and 50.5 grams of ethylene glycol monobutyl ether and another separate stream of 75.7 grams of the TBPB and 75.7 grams of the ethylene g]ycol monobutyl ether are added to the reaction mixture over a period of two hours. This mixture is held at reflux for one hour after the separate streams have been charged to the reaction vessel. Thereafter, the reaction is cooled to 120C~ at which time 8.4 grams of TBPB and 176.7 grams of ethylene glycol monobutyl ether are added over a period of one hour. This mixture is then held for one hour at 120C.

~46694 The resultant mixture has a solid3 content o~ 49.6 percent and a Gardner-l~oldt viscosity of R-F. The ~ispersant has a molecular weight of llQO.

EXAMPLE III
A reaction vessel is equipped as in Example I. The following components are used in the reaction:
Isobutyl methacrylate 1100.0 grams Methyl methacrylate466.5 grams Acrylic acid 42.1 grams Hydroxyethyl acrylate 42.1 grams Dimethylaminoethyl methacrylate 16.7 grams 2-Mercaptoethanol 16.7 grams ~A Propasol B 1521.1 grams Denatured ethyl alcohol 30.0 grams Ethyl alcohol 72.9 grams Tertiary butyl perbenzoate (TBPB) 84.1 grams Propasol B is an isomeric mixture of n-butoxy propanol available from the Union Carbide Corp.
The reaction vessel is initially charged with 1346.1 grams of Propasol B and the denatured ethyl alcohol. This solvent mixture is heated to reflux, i.e., about 145C. Thereafter over the next two hours, separate streams of (1) the acrylic acid, hydroxyethyl acrylate, isobutyl methacrylate, methyl methacrylate, dimethylaminoethyl methacrylate, 2-mercaptoethanol and 50.5 grams of the Propasol B and (2) 75.7 grams of the TBPB and 75.7 grams Propasol B are added. The temperature is adjusted to 120C. with the ethyl alcohol. Over the next one hour, 8.4 grams of TBPB
~i~ Tr~e ~rk :, 6f;S~

and 103.8 grams of Propasol B are added. lhis mixture i9 then held for one hour anci cooled.
The reaction mixture is comprised of 49.5 percent solids and has a Gardner-~oldt viscosity of K-L. The dispersant has a molecular weight of 2200.

EXAMPLE IV
The following components are used to produce a resin dispersant:
Isobutyl methacrylate1278.9 grams Methyl methacrylate302.~ grams Methacrylic acid58.9 grams Hydroxyethyl acrylate42.1 grams 2-Mercaptoethanol50.5 grams Ethylene glycol monobutyl ether 1648.0 grams Tertiary butyl perbenzoate ~TBPB) 84.1 grams Propylenimine lO.ô grams Denatured ethyl alcohol33.7 grams A reaction vessel is set Up as in Example I. Initially, 1346.1 grams of ethylene glycol monobutyl ether and 33.7 grams of the denatured ethyl alcohol are charged to the reaction vessel and heated to 144C.
Thereafter separate streams of (1) the methacrylic acid, hydroxyethyl acrylate, methyl methacrylate, 2-mercaptoethanol and 50.5 grams of the ethylene glycol monobutyl ether and of (2) 75.7 grams of TBPB and 75.7 grams of the ethylene glycol monobutyl ether are added to the reaction vessel. The temperature during this addition is maintained at 140C. with the addition made over a period of about 2 hours. The mixture is cooled to 120C. with ethanol and 177 grams of ethylene glycol monobutyl ether and ~ 2~ -11~6~i~4 8.4 grams of TI~PB are added over one hour. Ihe reaction is cooled to 55C.
and when this temperature is reached, the propylenimine i8 added and the reaction mixture held at 65-70C. for a time period of two hours.
The reaction mixture is analy~ed and found to contain 50.9 percent solids. It has a Gardner-Holdt viscosity of G-~. The dispersant's weight average molecular weight is 2600.

EXAMPLE V
A resin dispersant is made following the procedure of Example IV
except acrylic acid is used in place of the methacrylic acid, 1100.0 grams of the isobutyl methacrylate is used instead of the 1278.9 grams and 471.2 grams of the methyl methacrylate is used instead of the 302.9 grams.
The final reaction mixture contains 50 percent solids. The dispersant's weight average molecular weight is 3000.

~XAMPL~ VI
A resin dispersant is made following the procedure of Example III
except 933.7 grams of 2-ethylhexyl methacrylate is used in place of the isobutyl methacrylate and 633.6 grams, instead of 466.5 grams, of methyl methacrylate is used. The dispersant's weight average molecular weight is 4600.

EXA~PLE VII

Example III is repeated except butyl methacrylate is used in place of the isobutyl methacrylate, at the same level. The resultant solution containing the resin dispersant has a solids content of 49.6 percent. The weight average molecular weight of the dispersant is 5600 ~1~6~94 EXAMPLE VIII
Another res;n dispersant :i9 made following the procedure of Example IV except 1083.8 grams butyl methacrylate is used in place of the isobutyl methacrylate, 466.5 grams methyl methacrylates is used and 55.8 grams of acrylic acid is used in place of the methacrylic acid. The dispersant's weight average molecular weight is 5800.

EX~PLE IX
A resin dispersant using butyl methacrylate and styrene in place of isobutyl methacrylate and methyl methacrylate, respectively, and at equal levels is made using the procedure described in Example ~ -III. The resultant d;spersant's weight average molecular weight is 5600.

EXAMPLE X
The dispersant of Example III is used to formulate pigment dispersions having the following compositions:
Pigment Percent Dispersant Percent Solvent Percent Black tint (1) 20 16 64 White tint (2) 74 5.2 20.8 Yellow tint (3) 55 9 36 Red tint (4) 68 6.4 2506 Blue tint ~5) 20 16 64 Green tint (6) 18 16.4 65.6 (1) The pigment is a #6 Lamp Black available from General Carbon Co.

(2) The pigment is Titantium Dioxide R 960 available from E. I. Dupont De Nemours & Co., Inc.

(3) The pigment is Yellow Iron Oxide 1888D available from Pfizer Inc.

(4) The pigment is Red Iron Oxide R-3098 available from Pfizer Inc.
~c rr~de mc~t k

(5) The pi~ment is Phthalo Blue BT 42SD available from E. I. Dupont ~e ~emours & Co., Inc.

(6) The pigment is Phthalo Green ~T 751D available from E. I. Dupont De Nemours & Co., Inc.
The solvent is an isomeric mixture of n-butoxy propanol available from Union Carbide Corp. as Propasol B.
The p;~ent dispersions are made by first premixing the pig-ment, dispersant and solvent on a Cowles mixer for about 20 minutes to form a well wetted uniform mix. Next, the premix is gro~nd on a Sussmeyer mill until the resultant paste possesses a Hegmann ~rind Gauge reading of +7. Optionally, a portion of the dispersant and solvent is held back from the initial premixing step and is used to wash down the Sussmeyer mill.
The wash is added to ~he previously milled paste to form pastes having the above compositions.

EXAMPLE XI
The pigment dispersion of this invention is tested for tint compatibility with paints containing different film-forming resins as described below. The pigment dispersion used in this example is the black tint pigment dispersion of Example X.

Percent Percent Volatile Film-Forming Percent Pigment Carriers, Flow Resin Type Film-Former Dispersion Control Agents, etc.

(A) 80 percent tall oil 37.2 6.2 Balance ~atty acid alkyd resin cross-linked with 20 percent aminoplast (l) (B) Acrylic resin ~2) 32.5 5.4 (C) Vinyl toluene alkyd 24.8 4.1 "
copolymer (3) ~ ' ~ r~e ~

6~'~

(D) Acrylic/epoxy co- 20.7 3.5 "
polymer (4).
(~) Plasticized acrylic 22.4 3.7 "
lacquer (5) (F) Vinyl resin (6) 28.2 4.7 ~ _ (G) Medium oil alkyd 30.4 5.1 resin (7) (H) Acrylic/melamine 29.7 4.9 "
copolymer (8) (I) Nitrocellulose/ 16.7 2.8 "
alkyd lacquer (9) (1) The aminoplast is available from Monsanto Co. as Resimine 735.
(2) The acrylic resin is an internally cross-linked acrylic resin found in PPG Industries, Inc. DURACRON ~ 00.
(3) A vinyl toluated alkyd resin.
(4) A 90:10 blend~ of an internally cross-linked acrylic resin of Example ~j and EP~)N~1001~ available from Shell Chemical Co.
~5) An air dry lacquer acrylic resin having imine modification made by PPG Industries, Inc.
(6) A resin blend of 78 percent of a solution vinyl resin and 22 percent of a chlorinated paraffin.

(7) Derived from 59 percent soya oil, 29 percent phthalic anhydride and 12 percent pentaerythritol.

(8) A hydroxy functional acrylic resin cross-linked with an aminoplast.

(9) A 35/65 blend of a nitrocellulose solution and tall oil fatty acid glycerol alkyd resin.
Compatibility of the pigment dispersions with the film-forming resins in the respective paints and their effect on the properties of a formed film are determined using a series of tests. Initially, the paints are shaken for 10 to 15 minutes and allowed to digest overnight. Then 1.0 to 1.2 mil (dry) films of the paints on steel panels are formed by spraying.
~ r~ v~

i69~

Compatibility is determinecl by a rub-up test. Wh;le the films on the above-described steel panels are still wet, they are rubbed with the forefinger. Any lighten;ng of the color is noted. A noticeable change in color between the rubbed portion of the wet film and the unrubbed portion is an indication of incompatibility of the pigment dispersions in the paint. The following rub-up values are obtained based on a 0 to 10 scale with 0 being no change in color and 5 being the value above which a significant color change and hence a compatibiLity problem is experienced.
Paint Rub-up (A) 3 (B) (C) (D) 3 (E) 2 (F) 2 (G) 2 (H) (I) 1 The above results show that the pigment dispersion of this invention is compatible with a wide variety of film-forming resins.
The effect the pigment dispersions have on the properties of the formed films is determined using a (1) direct and reverse impact test, (2) pencil hardness test, and (3) intercoat adhesion test. The impact tests are conducted using a Gardner Variable Impact Tester. The pencil hardness test is a measure of the film's hardness. A hardness value is assigned a film based on its ability to withstand pressure applied by a pencil having a specified grade of lead. The intercoat 11~6694 adhesion test measures the ability of the forme(l ~ilm to adhere to a previously coated substrate.
In all instances, coating compositions (A)-(I) have substantially equivalent or better properties than controls where the above described pigment dispersions are omitted.

EX~MP~E XII
Resin dispersants made from the compounds indicated in the chart (expressed as percents) are tested for compatibility and their effect on film properties of a paint containing them. Resin dispersants A, B, C, D, E, F and G correspond with the dispersants of Examples III, V, I, VI, VII, VIII and IX, respectively.

Resin dispersant A B C D E F G
Isobutyl methacrylate6666 66 - - - -2-Ethylhexyl methacrylate - - - 56 Butyl methacrylate - - - - 66 65.5 66 Methyl methacrylate 28 28 27 38 28 28 Styrene - - - - - - 28 Acrylic acid 2.52.52.5 2.52.5 2.5 2.5 Hydroxyethyl acrylate2.52.52.52.5 2.5 2.5 2.5 Amino functional moiety(l) Amino functionai moiety(2) - 1 - - - 1.5 Amino functional moietyt3) ~ ~ 2 (1) The amino functional moiety is provided by polymerizing dimethyl-aminoethyl methacrylate into the resin dispersant's polymeric backbone.
(2) The amino functional moiety is provided by an aziridine ring opening reaction.
(3) An amine salt of the resin dispersant is formed from the dispersant and dimethyloctodecyl amine.

6~4 The above resin dispersants are tested by ndding them nt a 6 percent level to (1) an internally cross-linked acrylic resin based paint and (2) an alkyd/melamine based paint. Values for color development, rub-up and intercoat adhesion are obtained. The color development value is a measure of the resin dispersant's efficiency as determined by its ability to even]y disperse pigment throughout the dried film. A value of 1 is excellent, 10 poor and 5 marginally acceptable.

Cross-Linked Acrylic Resin Based Paint Resin Dispersant Color Development Rub-Up Adhesion A 4 3 o.k.
B 4 2 o.k.
C 3 2 o.k.
D 2 1 o.k.
E 2 2 o.k.
F 2 3 o.k.
G 2 1 o.k.

Alkyd/~elamine Resin Based Paiut Resin Dispersant Color Development Rub-Up Adhesion A 1 3 o.k.
B 3 3 o.k.
C 2 3 o.k.
D 2 3 - o.k~
E 2 3 o.k.
F 2 3 o.k.

G 2 3 o.k.

6~fl~

Ihe above results show the resin dispersants of this inven-t;on perform satisfactor;ly as pigmen~ dispersa~t3, are compatible with the tested coating composition and do not have an adverse effect on the formed film's intercoat adhesion.

Claims (57)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A dispersant compatible with a variety of resin-containing coating compositions and especially adapted for dispersing pigments therein, said dispersant being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 20 percent co about 85 percent of an alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 5 percent to about 60 percent of a hardening monomer selected from the group consisting of a styrene, methyl methacrylate, ethyl methacrylate and mixtures thereof;
(iii) from about 1 percent to about 25 percent of an ethylen-ically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride;
(iv) from about 1 percent to about 25 percent of a mono-mer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or an epoxide; and (v) from about 0.1 percent to about 15 percent of a compound providing an amine or amine salt functional moiety; and wherein said dispersant has a weight average molecular weight, determined by gel permeation chromatography, using a polystyrene standard, of from about 1,000 to about 10,000.

2. The dispersant of Claim 1 being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 40 percent to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 15 percent to about 40 percent of the hardening monomer;
(iii) from about 1 percent to about 20 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 15 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted;
and (v) from about 0.5 percent to about 3 percent of the compound providing an amine or amine salt functional moiety.

3. The dispersant of Claim 2 wherein monomer (iv) is a hydroxyl-containing alkyl acrylate or alkyl methacrylate wherein the alkyl group contains from 2 to 20 carbon atoms.

4. The dispersant of Claim 2 wherein monomer (iv) is a glycidyl acrylate or glycidyl methacrylate which is reacted with an acid to open the epoxide ring and form the carbonyl group having the alpha-beta unsaturation to the carbonyl group and at least one hydroxyl group.

5. The dispersant of Claim 2 wherein monomer (iv) is an acrylic or methacrylic acid which is reacted with an epoxide to form the carbonyl group having the alpha-beta unsaturation to the carbonyl group and at least one hydroxyl group.

6. The dispersant of Claim 2 wherein monomer (iii) is the ethylenically unsaturated carboxylic acid.

7. The dispersant of Claim 2 wherein the alkyl methacrylate is a branched chain methacrylate.

8. The dispersant of Claim 7 wherein the alkyl methacrylate is isobutyl methacrylate.

9. The dispersant of Claim 7 wherein the hardening monomer is styrene or methyl methacrylate.

10. The dispersant of Claim 9 wherein the ethylenically un-saturated carboxylic acid is acrylic acid or methacrylic acid.

11. The dispersant of Claim 3 wherein the hydroxyl-containing alkyl acrylate or alkyl methacrylate contains from 2 to 6 carbon atoms in the alkyl group.

12. The dispersant of Claim 11 wherein the hydroxyl containing alkyl acrylate or alkyl methacrylate is hydroxyethyl acrylate.

13. The dispersant of Claim 2 wherein the component providing an amine or amine salt functional moiety is an-aliphatic or alicyclic amine compound which forms a salt with the carboxyl moiety of the interpolymer.

14. The dispersant of Claim 2 wherein the component providing an amine or amine salt functional moiety is an acrylic or methacrylic compound containing amino groups.

15. The dispersant of Claim 2 wherein the amine or amine salt functional moiety is provided by a nitrogen-containing ring opening compound

16. The dispersant of Claims 1 or 2 additionally consisting essentially of from about 1 percent to about 30 percent of a monomer selected from the group consisting of alkyl esters of acrylic acid wherein the alkyl group contains from 3 to 20 carbon atoms, alkyl esters of methacrylic acid wherein the alkyl group contains from 9 to 20 carbon atoms and mixtures thereof.

17. The dispersant of Claims 3, 4 or 5 being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 60 percent to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 20 percent to about 35 percent of the hardening monomer;
(iii) from about 1 percent to about 15 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 10 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted; and (v) from about 0.5 to about 3 percent of the compound providing an amine or amine salt functional moiety.

18. The dispersant of Claim 2 being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 60 percent to about 80 percent of isobutyl methacrylate;
(ii) from about 20 percent to about 35 percent of styrene or methyl methacrylate;
(iii) from about 1 percent to about 15 percent of acrylic acid or methacrylic acid;
(iv) from about 1 percent to about 10 percent of hydroxyethyl acrylate.

19. The dispersant of Claim 18 wherein the dispersant has a weight average molecular weight of from about 2,000 to about 6,000.

20. A pigment dispersion composition adapted for dispersing pigments in a film-forming resin containing coating composition wherein said pigment dispersion composition consists essentially of:
(a) from about 1 percent to about 50 percent of a dispersant, said dispersant being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 20 percent to about 85 percent of an alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 5 percent to about 60 percent of a hardening monomer selected from the group consisting of a styrene, methyl methacrylate, ethyl methacrylate and mixtures thereof;
(iii) from about 1 percent to about 25 percent of an ethylenically unsaturated carboxylic acid selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride;
(iv) from about 1 percent to about 25 percent of a monomer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or an epoxide; and (v) from about 0.1 percent to about 15 percent of a compound providing an amine or amine salt functional moiety; and wherein said dispersant has a weight average molecular weight, determined by gel permeation chromatography, using a polystyrene standard, of from about 1,000 to about 10,000;
(b) from about 10 percent to about 90 percent of a pigment; and (c) the balance a liquid carrier.

21. The composition of Claim 20 wherein the dispersant is the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 40 percent to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;

(ii) from about 15 percent to about 40 percent of the hardening monomer;
(iii) from about 1 percent to about 20 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 15 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted; and (v) from about 0.5 percent to about 3 percent of the compound providing an amine or amine salt functional moiety.

22. The composition of Claim 21 wherein monomer (iv) is a hydroxyl containing alkyl acrylate or alkyl methacrylate wherein the alkyl group contains from 2 to 20 carbon atoms.

23. The composition of Claim 21 wherein monomer (iv) is a glycidyl acrylate or glycidyl methacrylate which is reacted with an acid to open the epoxide ring and form the carbonyl group having the alpha-beta unsaturation to the carbonyl group and at least one hydroxyl group.

24. The composition of Claim 21 wherein monomer (iv) is an acrylic or methacrylic acid which is reacted with an epoxide to form the carbonyl group having the alpha-beta unsaturation to the carbonyl group and at least one hydroxyl group.

25. The composition of Claim 21 wherein monomer (iii) is the ethylenically unsaturated carboxylic acid.

26. The composition of Claim 21 wherein the alkyl methacrylate is a branched chain methacrylate.

27. The composition of Claim 26 wherein the alkyl methacrylate is isobutyl methacrylate.

28. The composition of Claim 26 wherein the hardening mono-mer is styrene or methyl methacrylate.

29. The composition of Claim 28 wherein the ethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid.

30. The composition of Claim 22 wherein the hydroxyl-containing alkyl acrylate or alkyl methacrylate contains from 2 to 6 carbon atoms in the alkyl group.

31. The composition of Claim 30 wherein the hydroxyl-containing alkyl acrylate or alkyl methacrylate is hydroxyethyl acrylate.

32. The composition of Claim 21 wherein the component providing an amine or amine salt functional moiety is an aliphatic or alicyclic amine compound which forms a salt with the carboxyl moiety of the interpolymer.

33. The composition of Claim 21 wherein the component providing an amine or amine salt functional moiety is an acrylic or methacrylic compound containing amino groups.

34. The composition of Claim 21 wherein the amine or amine salt functional moiety is provided by a nitrogen-containing ring opening compound.

35. The composition of Claims 20 or 21 wherein the dispersant additionally consists essentially of from about 1 percent to about 30 percent of a monomer selected from the group consisting of alkyl esters of acrylic acid wherein the alkyl group contains from 3 to 20 carbon atoms, alkyl esters of methacrylic acid wherein the alkyl group contains from 9 to 20 carbon atoms and mixtures thereof.

36. The composition of Claims 22, 23 or 24 wherein the dis-persant is the polymerization product of:
(i) from about 60 percent to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 20 percent to about 35 percent of the hardening monomer;
(iii) from about 1 percent to about 15 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 10 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted; and (v) from about 0.5 percent to about 3 percent of the compound providing an amine or amine salt functional moiety.

37. The composition of Claim 21 wherein the dispersant is the polymerization product of:

(i) from about 60 percent to about 80 percent of isobutyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 20 percent to about 35 percent of styrene or methyl methacrylate;
(iii) from about 1 percent to about 15 percent of acrylic or methacrylic acid;
(iv) from about 1 percent to about 10 percent of hydroxyethyl acrylate; and (v) from about 0.5 percent to about 3 percent of the compound providing an amine or amine salt functional moiety.

38. The composition of Claim 37 wherein the dispersant has a molecular weight of from about 2,000 to about 6,000.

39. The composition of Claim 20 consisting essentially of:
(a) from about 3 percent to about 30 percent of the dispersant;
(b) from about 15 percent to about 80 percent of the pigment; and (c) the balance a liquid carrier.

40. The composition of Claim 39 wherein the carrier is an organic solvent.

41. The composition of claim 20 wherein the pigment is ground into the dispersant.

42. A coating composition consisting essentially of:
(a) from about 25 percent to about 98 percent of a film-forming resin;

(claim 42 cont'd) (b) from about 1 percent to about 70 percent of a pigment;
(c) from about 1 percent to about 50 percent of a dis-persant capable of dispersing the pigment in the liquid carrier and film-forming resin, said dispersant being the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 20 percent to about 85 percent of an alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 5 percent to about 60 percent of a hardening monomer selected from the group consisting of a styrene, methyl methacrylate, ethyl methacrylate and mixtures thereof;
(iii) from about 1 percent to about 25 percent of an ethylenically unsaturated carboxylic acid selected from the group consisting of an acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and mixtures thereof or a monomer having a double bond alpha-beta to a carbonyl group and which provides carboxyl functionality when reacted with water, alcohol, amine or anhydride;
(iv) from about 1 percent to about 25 percent of a monomer having a double bond alpha-beta to a carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted with an acid or an epoxide;
and (v) from about 0.1 percent to about 15 percent of a compound providing an amine or amine salt functional moiety;

wherein said dispersant has a molecular weight determined by gel permeation chromatography, using a polystyrene standard, of from about 1,000 to about 10,000; and (d) the balance a liquid carrier.

43. The composition of Claim 42 wherein the dispersant addi-tionally consists essentially of from about 1 percent to about 30 percent of a monomer selected from the group consisting of alkyl esters of acrylic acid wherein the alkyl group contains from 3 to 20 carbon atoms, alkyl esters of methacrylic acid wherein the alkyl group contains from 9 to 20 carbon atoms and mixtures thereof.

44. The composition of Claim 42 wherein the alkyl methacrylate is a branched chain methacrylate, the hardening monomer is styrene or methyl methacrylate, the ethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid and the monomer having the carbonyl group and the alpha-beta unsaturation to the carbonyl group is a hydroxyl-containing alkyl acrylate or alkyl methacrylate wherein the alkyl group contains from 2 to 20 carbon atoms.

45. The composition of Claim 42 wherein the film-forming resin is an acrylic resin.

46. The composition of Claim 42 wherein the film-forming resin is an alkyd resin.

47. The composition of Claim 42 wherein the film-forming resin is a polyester resin.

48. The composition of Claim 42 wherein the film-forming resin is an epoxy resin.

49. The composition of Claim 42 wherein the film-forming resin is a cellulose derivative resin.

50. The composition of Claim 42 wherein the film-forming resin is a vinyl resin.

51. The composition of Claim 42 wherein the film-forming resin is a urethane resin.

52. The composition of Claim 42 wherein the film-forming resin is an aminoplast resin.

53. The composition of Claim 42 wherein the film-forming resin is a phenoplast resin.

54. The composition of Claim 42 wherein the film-forming resin is an amide resin.

55. The composition of Claim 42 wherein the dispersant is the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 40 percent to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;
(ii) from about 15 percent to about 40 percent of the hardening monomer;

(iii) from about 1 percent to about 20 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 15 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted; and (v) from about 0.5 percent to about 3 percent of the compound providing an amine or amine salt functional moiety.

56. The composition of Claim 55 wherein the dispersant is the polymerization product of a mixture of monomers consisting essentially of:
(i) from about 60 to about 80 percent of the alkyl methacrylate having from 3 to 8 carbon atoms in the alkyl group;

(ii) from about 20 percent to about 35 percent of the hardening monomer;
(iii) from about 1 percent to about 15 percent of the ethylenically unsaturated carboxylic acid or the monomer which provides the carboxyl functionality when further reacted;
(iv) from about 1 percent to about 10 percent of the monomer having a double bond alpha-beta to the carbonyl group and at least one hydroxyl group or a monomer which provides such groups when further reacted; and (v) from about 0.5 percent to about 3 percent of the component providing an amine or amine salt functional moiety; and wherein the polymerization product has a molecular weight of from about 2,000 to about 6,000.

57. The composition of Claim 55 or 56 wherein the alkyl methacrylate is a branched chain methacrylate, the hardening monomer is styrene or methyl methacrylate, the ethylenically unsaturated carboxylic acid is acrylic acid or methacrylic acid and the monomer having the carbonyl group and the alpha-beta unsaturation to the carbonyl group is a hydroxy-containing alkyl acrylate or alkyl methacrylate wherein the alkyl group contains from 2 to 20 carbon atoms.