CA2017505A1

CA2017505A1 - Dispersions for coatings without external crosslinking agents

Info

Publication number: CA2017505A1
Application number: CA 2017505
Authority: CA
Inventors: Suryya K. Das; James R. Bodwell
Original assignee: PPG Industries Inc
Current assignee: PPG Industries Inc
Priority date: 1990-04-03
Filing date: 1990-05-24
Publication date: 1991-10-03

Abstract

ABSTRACT

Disclosed is an anionic emulsifier-free, aqueous dispersion which does not require an external crosslinking agent to provide coatings having good water and organic solvent resistance. The aqueous dispersion comprises an amine-containing polymer in combination with an acid-functional polymeric dispersant which has been neutralized by a fugitive amine. The "amine" of the amine-containing polymer is fixed as a result of being present in the polymer so as not to be volatile from a film from the final polymer dispersion product and yet be capable of interaction with acid functionality from the acid-functional polymeric dispersant.
Also disclosed is a two stage method for preparing a preferred anionic emulsifier-free polymer dispersion product. The two stage method is characterized, in part, in that the mixture of polymerizable monomers for the first stage polymerization comprises an ethylenically unsaturated carboxylic acid or anhydride and at least one copolymerizable ethylenically unsaturated monomer different from the carboxylic acid or anhydride. The two stage method is also characterized, in part, in that the mixture of polymerizable monomers for the second stage polymerization comprises an ethylenically unsaturated monoamine and at least one ethylenically unsaturated monomer different from and copolymerizable with the ethylenically unsaturated monoamine.

Description

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8 BACK~OUND OF THE I~VENTION
The present invention relates to aqueous polymer dispersions ;~
10 and more particularly to aqueous polymer dispersions prepared by polymerizing ethylen~cally un~aturated monomers or mixtures of such 12 monomers in the presence of a polymeric dispersant. ~ :
U.S. Patent No. 4,151,143 discloses the preparation of 14 emul~iion coating compositions characterized as being surfactant-free produced by a two stage process. The first stage involves production 16 of a conventional carboxyl group-containing polymer from a mixture of monomers composed of about 3-15 percent of a polymerizable carboxylic 18 acid or anhydride and at least one other polymerizable monomer. The resulting carboxyl group-containing polymer of the first ~tage i8 then 20 water-dispersed (or solubilized) by neutralization with an organic - -amine or base. In the second stage, a blend of "partially 22 water-soluble and p-rtially water-insoluble" monomers, along with a free radical initiator, is added to the neutralized polymer of the 24 first stage, ant the resulting mixture is heated to effect polymerization and protuce the polymer emulsion product to which the ~; 26~patent~is directed.~ It i8~ further disclosed therein that the monomer mixture for the socond stage contains no polymerizable acid, but is - 28~composed of monomers such as methyl, ethyl, propyl, and butyl acrylates or methacryiates, beta-hydroxyethyl and beta-hydroxypropyl acrylate or 30 methacrylate, acrylamite and isobutoxymethyl acrylamide, and optionally acrylonitr~le and styrene. By eliminating the presence of external 32 surfactants from the resulting emulsion coating, the water and humidity resistaDce of hardened films produced therefrom is improved.

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h317 While such a two stage process as disclosed in U.S. Patent 2 No. 4,151,143 provides certain advantages, the resulting emulsion coatings, unless formulated and cured with an external crosslinking 4 agent such as an amino resin-type crosslinking agent, exemplifled by hexamethoxymethyl melamine, tend not to provide a desirable degree of 6 organic solvent reslstance.
One ob~ect o the present invention is to provide an anionic 8 emulsifier-free, aqueous dispersion which can provide hardened films having both good water (and humidity) resistance and good organic 10 solvent resistance without the need for utilizing external crosslinking agents. Other ob~ects of the invention will become apparent to the 12 reader infra.

14 ~UM~ OF T~ INVENTIQy The present invention provides an anionic emulsifier-free, 16 aqueous dispersion which does not require an external crosfilinking agent to provide films (coatings) having a desirable combination of 18 both good resistance to water and humidity as well as good resistance to organic solvents. An aqueous dispersion of the invention comprises 20 an amine-containing polymer in combination with an acid-functional polymeric dispersant (e.g., containing carboxyl, acid anhydride, 22 sulfonic acid or an acid group of a monophosphate) which has been neutralized by a volatile (fugitive) amine. The "amine" of the 24 am~ne-containing polymer can be considered as being a "fixed" or "bound" amine, that is fixed as a result of being chemically bound in 26 the polymer 80 as not to be volatile from a film from the final polymer dispersion product and yet be capable of interaction with acid -~
28 functionality from the acid-functional polymeric dispersant. ~ -Additionally,i typically the basicity of the "fugitive" amine for 30 neutralization is stronger than the basicity of the "fixed" amine for the amine-containing polymer 80 as to enhance stability of an aqueous 32 dispersion of the invention.
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~a 17~, The present invention also provides a two stage method for 2 preparing a preferred anionic emulsifier-free polymer dispersion product which does not require an external crosslinking agent to 4 provide films having the aforesaid combination of good water and organic solvent resistance. The two stage method is characterized, in 6 part, in that the mixture of polymer~zable monomers for the first stage polymerization comprises from 5.0 to 85 percent by weight of an 8 ethylenically unsaturated carboxylic acid or anhydride and from 15 to 95 percent by weight of at least one copolymerizable ethylenically 10 unsaturated monomer different from the carboxylic acid or anhydride.
The first stage polymerization results in the formation of an 12 acid-functional polymeric dispersant having a weight average molecular weight of from about 500 to about 100,000. The polymeric dispersant is 14 neutralized with a water-soluble, volatile amine (alternatively referred to herein as a "fugitive amine") to an extent required to make 16 the polymeric di6persant water-dispersible or water-soluble.
The two stage method of the present invention is also 18 characterized, in part, in that the mixture of polymerizable monomers for the second stage polymerization comprises from 8.0 to 50 percent by 20 weight of an ethylenically unsaturated monoamine, preferably having a limited water solubility, the monoamine being present in tbe second 22 mixture in an amount sufficient to provide a ratio of equivalents of amine groups from the monoamine to equivalents of acid (carboxyl) 24 groups from the polymeric dispersant in a range of from 0.15:1.0 to 1.0:1Ø The mixture of polymerizable monomers for the second stage 26 polymerization also comprises from 50 to 92 percent by weight of at least one ethylenically unsaturated monomer different from and 28 copolymerizable with the ethylenically unsaturated monoamine.
' Afber or during film formation on a substrate from a polymer 30 dispersion product of the invention? fugitive amine evaporates from the film; hence use of the word "fugitive". Also, after or during film 32 formation, as the fugitive amine evaporates, salt formation, believed to result from interaction of the acid and fixed amine functionalitles 34 of the two polymers, occurs making the resultant film from the polymer dispersion product surprisingly resistant to organic solvent such as 36 methylethyl ketone, acetone, etc.

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DET~IL~D D~SÇ~IPTIqN OF~GEi_L~ Iln~
2An anionic emulsifier-free, aqueous disper~ion of the invention comprises an amine-containing polymer in combination with an 4 acid functional polymeric dispersant neutralized by a (fugitive) volatile amine. The fixed amino groups from the amine-contalning 6 polymer and acid groups (e.g., carboxyl, acid anhydride, sulfonic acid or acid group of a monophosphate) from the acid-functional polymeric 8 dispersant are present in the aqueous dispersion product in relative amounts sufficient such that vaporization of the volatile amine from a 10 wet one mil thick film from the dispersion, devoid of any external crosslinking agent, drawn down on a paper substrate and subjected to a lZ predetermined temperature for a period of time, will result in salt formation between the fixed amino groups from the amine-containing 14 polymer and acid groups from the carboxyl-functional polymeric dispersant sufficient to provide a dry, organic solvent-resistant and 16 water-resistant, film.
Generally, the fixed amine functionality from the amine-18 containing polymer and the acid functionality from the acid-functional -polymeric dispersant are balanced such that a wet one mil thick film 20 from a polymer dispersion of the invention, devoid of any external -crosslinking agent, when drawn down on a printed (simulated wood grain) 22 paper substrate (23 gramlmeter2 printing paper) laminated to a rigid unterlying substrate such as particleboard and subjected to a ~-24 predetermined temperature for a period of time to dry and harden the ~
film will result in a dry film which exhibits an acetone resistance of ~ ;
26 at least one minute, preferably at least 1 1/2 minutes, and a water resistance of at least two minutes, preferably at least five minutes.
28 As used herein, acetone resistance of the dry film is determined by placing 2 to 3 drops of acetone directly on the dry film, 30 allowing the acetone to remain on the film for a predetermined period of time~ wiping the acetone away with a cloth, and observing the film 32 for breakthrough (failure) in the area tested. Failure occurs in this test by dissolution of the film such that the film is broken through 34 allowing the acetone to attack the underlying substrate. For example, ~-:

~17~5 in thi6 te6t~utilizing the printed paper, when breakthrough occurs, the 2 acetone deteriorates the ink of the underlying printed area such that the paper becomes discolored (e.g. lightens in the printed area).
4 As used herein, water resistance of the dry film ~s determined by placing 2 to 3 drops of water directly on the dry film, 6 covering with a watch glass, allowing the water to remain on the film for a predetermined period of time, wiping the water away with a cloth, 8 and observing the film for failure in the area tested. Failure occurs in this test by softening of the film and the underlying paper such 10 that film and paper can be removed by scratching with a fingernail.
As used herein, the term "anionic emulsifier-free" is to be 12 understood to apply to an aqueous dispersion of the invention containing from 0 to 2.0 percent by weight, preferably less than 1.0 14 percent by weight, of anionic emulsifier based on the combined weight of amine-containing polymer and acid-functional polymeric dispersant in 16 the aqueous dispersion.
Without intending to be bound thereby, it is believed that 18 the surprising organic solvent resistance of a dry film from a composition of the invention results from the interaction between the 20 fixed amino groups from the amine-containing polymer and acid groups from the Pcid-functional polymeric di~persant as in a ~alt or polysalt 22 formed from the respective polymers.
Generally, fixed amino groups from the amine-containing 24 polymer and acid groups from the acid-functional polymeric dispersant are present in an aqueous dispersion of the invention in relative 26 amounts sufficient to provide a ratio of equivalents of the fixed amino groups to equivalents of the acid groups in a range of from 0.15:1.0 to 28 1.0:1.0, preferably from 0.25:1.0 to 0.75:1Ø Generally, to enhance stability of an aqueous composition of the invention, the 30 amine-containing polymer of an aqueous dispersion of the invention is essentially acid-free, meaning that the composition of monomers 32 utilized to prepare the amine-containing polymer contains not more than 5 percent by weight, preferably not more than 2 percent by weight, and 34 most preferably 0 percent by weight, of acid-functional monomer.

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An aqueous dispersion product of the invention can be 2 prepared, for example, by emulsion polymerization or suspension polymerization. For example, an aqueous dispersion product of the 4 invention can be prepared by the following two stage method, which illustrate6 a preferred method for preparing a preferred aqueous 6 dispersion product of the in~entlon. Given the disclosure taken as a whole herein, other methods will become apparent. In the first stage, ~ -8 a first mixture of polymerizable monomers comprising by weight from 5.0 ~-to 85 percent, preferably from 20 to 65 percent, of an 10 alpha,beta-ethylenically unsaturated carboxylic acid or anhydride and ~
fro~ 15 to 95 percent, preferably from 35 to 80 percent, of at least ~-12 one copolymerizable alpha,beta-ethylenically unsaturated monomer different from said carboxylic acid or anhydride, is polymerized at a 14 temperature generally in the range of from 65C to 125C, preferably - ~
from 90C to lI0C, in the presence of a polymerization initiator, a -;
16 suitable solvent, and optionally a molecular weight regulator to form a polymeric dispersant (as yet unneutralized) having a weight average 18 molecular weight of from about 500 to about 100,000, preferably from about 1,500 to about 40,000 as determined by gel permeation 20 chromatography (GPC) using a polystyrene standard. The resulting polymeric dispersant is neutralized with a water-soluble, volatile 22 amine (i.e., the fugitive amine) to an extent required to make the polymeric disperaant water-dispersible or water-soluble, and a ~
24 dispersion or solution of the polymeric dispersant is formed in the ~ ~-aqueous medium. Examples of fugitive amines suitable for 26 neutralization of the polymeric dispersant include: ammonia (considered herein to be an amine), ethanolamine, diethanolamine, -28 N-methylethanolamine, N,N-dimethylethanolamine, methylamine, ethylamine, diethylamine, tri~ethylamine, triethylamine and morpholine.
In the second stage, a second mixture of polymerizable monomers comprising by weight from 8.0 to 50 percent, preferably from 32 10 to 30 percent, of an alpha,beta-ethylenically unsaturated monoamine, preferably having a limited water solubility, is combined with and 34 copolymerized with the dispersion or solution of the polymeric dispersant in water from the first stage. The monoamine is present in h (~ l 7 the second mixture in an amount gufficient to provide a ratio of 2 equivalent~ of amine groups from the monoamine to equivalents of carboxyl groups from the polymeric dispersant in a range of from 4 0.15:1.0 to 1.0:1.0, preferably in a range of from 0.25:1.0 to 0.75 to 1Ø The Gecond mixture of polymerizable monomers al60 comprises by 6 weight from 50 to 92 percent of at least one copolymerizable alpha,beta-ethylenically unsaturated monomer different from the 8 alpha,beta-ethylenically unsaturated monoamine. The relatlve amounts of the first and second mixtures of polymerizable monomers for 10 preparation of a dispersion of the invention are such that the amount of the second mixture of polymerizable monomers provides an amount by 12 weight of from about 40 to about 95 percent, of the total combined weight of the first and second mixtures of polymerizable monomers. The 14 second mixture of polymerizable monomers and a polymerization initiator is combined with the aqueous dispersion or solution produced in the 16 first stage discussed above. The combined mixture 80 formed is then heated to effect polymerization and produce a polymer dispersion 18 product of the invention.
As discussed above, the first mixture of polymerizable 20 monomers contains an alpha,beta-ethylenically unsaturated carboxylic acid or anhydride. The ethylenically unsaturated acid contains at 22 least one polymerizable double bond and at least one acid group, preferably one CH2=0< group and one carboxylic acid group, and 24 preferably contains from 3 to 12 carbon atoms. While acrylic acid and methacrylic acid are preferred, other suitable ethylenically 26 unsaturated carboxylic acid monomers may be used such as itaconic acid, ~-crotonic acid, maleic acid, and Cl to C8 alkyl half-esters of maleic 28 and fumaric acids, such as butyl hydrogen maleate and ethyl hydrogen fumarate, in~which one carboxyl group is esterified with an alcohol.
The first mixture of polymerizable monomers also contains at least one copolymerizable alpha,beta-ethylenically unsaturated monomer 32 different from the unsaturated carboxylic acid or anhydride. Examples of other ethylenically unsaturated monomers which can be used include 34 the alkyl acrylates, such as methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, 2-ethylhexyl acrylate and isobornyl ~ ;'"' '';' "" ' ' ' ' ' ' ' " ' ' ' : ' ~ . ' , .

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acrylate; the alkyl methacrylates, such as methyl methacrylate, butyl 2 methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate and isobornyl methacrylate; hydroxyalkyl acrylates and -~-4 methacrylates such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate;
6 N-alkoxymethyl acrylamides and methacrylamides such as N-butoxymethyl acrylamide, N-butoxymethyl methacrylamide, N-ethoxymethyl acrylamide 8 and N-ethoxymethyl methacrylamide; and unsaturated nitriles, such as acrylonitrile, methacrylonitrile and ethacrylonitrile. Other 10 ethylenically unsaturated monomers (vinyl monomers) which may be used in addition to the aforesaid monomers include: vinyl aromatic 12 hydrocarbons (optionally substituted, for example, by halo atoms) such as styrene, alpha-methyl styrene, alpha-chloromethyl styrene and vinyl 14 toluene; and vinyl aliphatic hydrocarbons (optionally substituted, for example, by halo atoms) such as vinyl acetate and vinyl chloride. The :~
16 selection of such other ethylenically unsaturated monomers for the first mixture of polymerizable monomers i8 not particularly limited 18 provided that such other monomers do not contain functionalities that would, in the amounts employed, interfere with production of the 20 carboxyl-functional product, for example, utilization of interfering amounts of unsaturated monomers, such as 1,2-epoxy functional 22 ethylenically unsaturated monomers, which would react with carboxyl functionality of the ethylenically unsaturated carboxylic acid or 24 anhydride to a deleterious degree under the reaction conditions for polymerization.
26 Organic solvents which may be utilized in the polymerization of the first mixture of polymerizable monomers include virtually any of 28 the organic solvents heretofore employed in preparing conventional --!acrylic or vlnyl addition polymers such as, for example, alcohols, 30 ketones, aromatic hydrocarbons or mixtures thereof. Illustrative of organic solvents of the above type which may be employed are alcohols ~--32 such as lower alkanols containing 2 to 4 carbon atoms including ethanol, propanol, isopropanol, and butanol, and simple glycols such as 34 ethylene glycol and propylene glycol; ether alcohols such as ethylene :~
glycol monoethyl ether, ethylene glycol monobutyl ether, propylene ,, , ~ , j; ' , !; ; . ` ' . ' ' ' ` ~ ' ~730~ -glycol monomethyl ether, and dipropylene glycol monoethyl ether;
2 ketones ~uch as methyl ethyl ketone, methyl N-butyl ketone, and methyl isobutyl ketone; esters such as butyl acetate; and aromatic 4 hydrocarbons such as xylene, toluene, and naphtha.
A vinyl polymerization initiator i8 employed in the 6 preparation of a resin of the invention. Examples of initiators include: perbenzoates such as tertiary-butyl perbenzoate; peroxides 8 such as benzoyl peroxide and cumene hydroperoxide; peracetates such as tertiary butyl peracetate; azo compounds such as alpha 10 alpha'-azobis(isobutyronitrile); percarbonates such as isopropyl percarbonate, peroxycarbonates 6uch as butyl isopropyl peroxy 12 carbonate, and similar compounds. The quantity of initiator employed can be varied considerably however, in most instances, it is deslrable 14 to utilize from about 0.1 to about 10 percent by weight based on the weight of ethylenically unsaturated monomers used. Where desired, 16 although not preferred, a molecular weight regulator such as a chain modifying agent or chain transfer agent can be added to the -18 polymerization mixture for control of the molecular weight of the resulting polymeric disper~ant. Examples of such agents include the 20 mercaptans, such as tertiary dodecyl mercaptan, dodecyl mercaptan, octyl mercaptan, and hexyl mercaptan.
22 Polymerization of the first mixture of polymerizable monomers to farm the polymeric dispersant (as yet unneutralized) is typically 24 conducted by free radical, organic solution polymerization techniques generally known in the art.
26 As discussed above, the second mixture of polymerizable monomers compriseg an alpha,beta-ethylenically unsaturated monoamine, 28 preferably having a limited water solubility. The alpha,beta-ethylenically unsaturated monoamine may be a primary, 30 secondary, or a tertiary amine. Examples of such unsaturated monoamines include essentially water insoluble monoamines such as 32 tertiary-butylaminoethyl methacrylate and meta-isopropenyl-alpha, alpha-dimethylbenzylamine, and partially water soluble monoamines such 34 as diethylaminoethyl methacrylate, the essentially insoluble monoamines , ~7 ~ ... . . , .. . ~ . . , I

,, ~" 10 being preferred, t-butylaminoethyl methacrylate being particularly 2 preferred. The more water 801uble monoamines such as dimethylaminoethyl methacrylate may also be employed where desired, for example, either 4 alone or in combination with an essentially water insoluble unsaturated monoamine such a~ t-butylaminoethyl methacrylate or with a partially 6 soluble monoamine ~uch as diethylaminoethyl methacrylate, although - ~
monoamines having such higher degree of water solubility typically are ~-8 not employed in preferred embodiments of the present invention. In the preferred embodiment, the ethylenically unsaturated monoamine i8 10 selected to promote transfer of the monoamine into the particulate phase during the second stage polymerization rather than remain in the 12 aqueous med~um. Unsaturated diamines or higher amino-functional unsaturated amines typically are not employed, and if so, should not be 14 employed in amounts 80 as to cause flocculation or gelation in the second stage polymerization.
16 As discussed above, the second mixture of polymerizable monomers also comprises at least one copolymerizable ethylenically 18 unsaturated monomer different from the ethylenically unsaturated monoamine. Examples of such copolymerizable monomers for the second ~-~
20 mixture which may be utilized include: alkyl acrylates, alkyl methacrylates, hydroxyalkyl acrylates and methacrylates, N-alkoxymethyl 22 acrylamides and methacrylamides, unsaturated nitriles, vinyl aromatic ~- -hydrocarbons (optionally substituted), and vinyl aliphatic hydrocarbons 24 (optionally substituted), examples of which copolymerizable monomers are set forth above in the description of other ethylenically 26 unsaturated monomers which may be utilized in the first mixture of ;~
polymerizable monomers. The selection of such other copolymerizable 23 monomers for the ~econd mixture of polymerizable monomers is not particularly limited. Of the examples of copolymerizable monomers set 30 forth above, the alkyl acrylates, alkyl methacrylates and vinyl ;~
aromatic hydrocarbons are preferred. In a particularly preferred 32 embodiment of the invention, the second mixture of polymerizable ;~
monomers additionally comprises by weight from 1 to 10 percent, 34 preferably from 1 to 2 percent, of a copolymerizable ethylenically unsaturated monomer having one 1,2-epoxy group (a copolymerizable ~3~7~

ethylenically un~aturated monoepoxide). Examples of such unsaturated 2 monoepoxides include: glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methallyl glycidyl ether and glycidyl esters of 4 polymerizable polycarboxylic acids such as maleic acid, fumaric acid, and crotonic acid. Preferred are the epoxy-functional acrylates such 6 as glycidyl acrylate, epoxy-functional methacrylates such as glycidyl methacrylate, or mixtures thereof, glycidyl methacrylate being 8 particularly preferred. It is believed that utilizat~on of a low level of ethylenically unsaturated monoepoxide promotes chemical bonding of 10 the polymeric surfactant to the other copolymerized monomers (during copolymerization~ and it helps to render more compatible the 12 acid-functional polymer and amine-containing polymer.
As discus~ed above, the second mixture of polymerizable 14 monomers and a polymerization initiator is combined with the aqueous dispersion or solution produced in the first stage discussed above.
16 The combined mixture 80 formed is then heated to effect polymerization and produce a polymer dispersion product of the invention.
18 Polymerization is usually conducted at a temperature below 100C, typically at temperatures between 20C and 85C. Polymerization 20 initiators which may be used include one or more peroxides or persulfates which are known to act as free radical initiators and which 22 are soluble in the aqueous medium. ~xamples include the persulfates such as ammonium, sodium and potassium persulfates. Also, oil-soluble 24 initiator may be employed either alone or in addition to the water-soluble initiator. Typical oil-soluble initiators include:
26 organic peroxides, such as benzoyl peroxide, tertiary-butyl peroxide and cumene hydroperoxide; perbenzoates such as tertiary-butyl 28 perbenzoate; peracetates such as tertiary butyl peracetate; azo initiators such as alpha alpha'-azobis(isobutyronitrile); percarbonates 30 sucb as isopropyl percarbonate; peroxycarbonates such as butyl isopropyl peroxy carbonate; and similar compounds. The quantity of 32 initiator employed can be varied considerably; however, in most instances, it is desirable to utilize from about 0.1 to about 10 34 percent, typically from about 0.50 to about 5.0 percent, by weight based on the weight of ethylenically unsaturated monomers used.

- 12 - :
hal730 The following examples illustrate the invention and should 2 not be construed as a limitation on the scope thereof. Unlefis specifically indicated otherwise, all percentage~ and amounts are 4 understood to be by weight. Wherever used herein "PBW" means part~ by weight .

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~D~ 7a~3 Examp~,el 2 This example illustrates the preparation of a di~persion of the lnvention.

Parts by weight Parts by weight 6 Ingredients (grams) (~olid~_ Initial C,,ha~g~
deionized water 217.5 12 ammonium persulfate 2.2 2.2 14 Pre-em~laiQn 16 deionized water 208.2 Acryllc disper~antl734.2 170.2 18 tertiary butylaminoethyl methacrylate 87.4 87.4 20 methyl methacrylate324.0 324.0 ethyl acrylate 74.0 74.0 22 glycidyl methacrylate8.0 8.0 (1) This polymeric acrylic dispersant was prepared from 70 percent 26 styrene, 29 percent acrylic acid and 1 percent ethyl acrylate on a weight basis.

A reaction vessel equipped with condenser, thermometer, addition funnels and nitrogen inlet and outlet tubes was charged with 32 the initial charge and heated to about 78C. Ten (10) percent of the pre emul~ion (about 150 ml) was added to the vessel and the mixture 34 held at 78C for about 20 minutes. The reaction exothermed and heating was discontinued until the temperature fell to about 78C.
36 Subsequently, the remaining pre emulsion was added over a 2 hour period. Thereafter? the reaction mixture was held at 78C for 'two 38 hours. The contents of the reactor vessel were cooled and filtered.

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~xiample 2 2 This example illustrates the preparation of a further dispersion of the invention.
4 Parts by weight Parts by weight Ingredi~ts (grams) (solids) 8 Initial Charg~
10 deionized water 217.5 ~`
ammonium persulfate 2.2 2.2 14 Pre-emul6ion delonized water 319.9 16 Acrylic dispersant2 586.2 170.2 ~-tertiary butylaminoethyl ; -18 methacrylate 46.8 46.8 methyl methacrylate 378.2 378.2 20 ethyl acrylate 88.7 88.7 glycidyl methacrylate 8.6 8.6 Addi~ion 1 28 percent ammonium solution 58.6 28 (2) This polymeric acrylic dispersant was prepared from 30 percent methyl methacrylate, 30 percent ethyl acrylate and 40 percent acrylic acid on 30 a weight basis. ~-A reactor vessel equipped as described in Example 1, above, 34 was charged with the initial charge and heated to about 78C. Ten - ~-percent of the pre-emulsion was added to the vessel and the mixture 36 held at about 78C for 20 minutes. Sub6equently, the remaining ~ pre-emulsion was added over 2 hours. Thereafter, the reaction mixture 38 was held at about 78C for 2 hours followed by Addition 1 whic4 was added over a 30 minute period. This reaction was scrapped because the 40 ammonium solution did not mix in.

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Example 3 2 Thi8 example illustrates the preparation of yet another dispersion of the invention.
4 Parts by weight Parts by weight In~redients (~rams) (sQlid~) 8 Initial Ch~g~
10 deionized water 217.5 ammonium persulfate 2.2 2.2 ~re-emul~ion deionized water 313.9 16 Acrylic dispersant of footnote 2 586.Z 170.2 ammonium hydroxide 58.6 18 tertiary butylaminoethyl methacrylate 87.4 87.4 20 methyl methacrylate 324.0 324.0 methyl acrylate 74.0 74.0 22 glycidyl methacrylate 8.0 8.0 24 A reactor vessel equipped as described in Example 1, above, was charged with the initial charge and heated to about 78C. In 26 preparing the pre-emulsion, the ammonium hydroxide solution was added to the dispersant before adding to the other ingredients of the 28 pre-emul6ion. Ten percent of the pre-emulsion was added to the vessel and the mixture held at about 78C for about 20 minutes. Subsequently, 30 the remaining pre-emulsion was added over a 2 hour period. Thereafter, the reaction mixture was held at about 78C for 2 hours. The reaction 32 mixture was cooled and filtered.

34 Example 4 This example illustrates yet another dispersion accor!ding to 36 the present invention.
38 Parts by weight Parts by weight IngFedi_nt~ ~gra~s) (solid9 ?

42 InitiaL Charge 44 deion~zed water 217.5 ammonium persulfate 2.2 2.2 ~3~73~
Pre-emul6ion deionized water 313.9 4 Acrylic dispersant of footnote 2 586.2 170.2 28% ammonium solution 58.6 6 tertiary butylaminoethyl methacrylate 46.8 46.8 8 methyl methacrylate 378.2 378.2 ethyl acrylate 88.7 88.7 10 glycidyl methacrylate 8.6 8.6 12 A reactor vessel equipped as described in Example 1, above, was charged with the initial charge and heated to 78C. Ten percent of 14 the pre-emulslon was added over a 5 minute period and held for 15 minutes at about 78C. The reaction exhibited a slight exotherm.
16 Subsequently, the remaining pre-emulsion was added over a 2 hour period. Thereafter, the reaction mixture was held at about 78C for 2 18 hours. The mixture was allowed to cool and filtered.
':
~xampl~_5 This example illustrates yet another dispersion according to ~
22 the present invention. -24 Parts by weight Parts by weight Ingrediell~ (gr~m~ (solids) 28 Initial Charge 30 deionized water 217.5 -~
ammonium persulfate 2.2 2.2 Pre-emulsion delonized water 313.9 36 Acrylic dispersant of footnote 2 506.2 170.2 28% ammonium solution 58.6 38 tertiary butylaminoethyl -methacrylate 23.4 23.4 40 methyl methacrylate 428.4 428.4 ethyl acrylate 96.0 96.0 42 glycidyl methacrylate 8.3 8.3 44 This example was prepared in the manner described above for the previous examples. -~017a~
Example 6 2 This example illustrateg yet another di~persion according to the present invention.

Parts by weight Parts by weight 6 Ingre~lents (~ram~) (solids) Initial ~ha~g~
deionized water 217.5 12 ammonium persulfate 2.2 2.2 14 Pre-~mul~iQn 16 deionized water 313.9 Acrylic dispersant of footnote 2 586.2 170.2 18 28% ammonium solution58.6 tertiary butyla~inoethyl 20 methacrylate 22.0 22.0 methyl methacrylate 428.4 428.4 22 methyl acrylate 96.0 96.0 glycidyl methacrylate 8.3 8.3 Th~s example was prepared in the manner described above for 26 the previous examples.

28 ExampLe_7 This example illustrates the preparation of and properties of 30 a coating from a coating composition utilizing a dispersion of the invention.
32 . -~
Parts by weight 34 Ingredien~$ (grams) 36 Dispersion of Example 5 298.00 , , ethylene glycol monobutyl ether 6.25 38 M-PYROL 1.88 Q 2-71193 3.76 40 SURFYNOL 104A4 3.76 28% ammonia water 3.50 44 (3) This is a polymethyl siloxane silicone fluid from Dow Corning.
46 (4) This is a non-ionic surfactant from Air Products.
-'. .'-':

~3i73~ -The resulting coating composition of the invention had a 2 solids content of 42.0 percent.
A first, thin layer of clear, wet film of coating composition 4 was applied by direct roll coat to the surface of a 23 gram/meter2 decorative paper imprinted with a wood pattern which paper was 6 laminated to 8 particleboard sub~tri~te. The resulting wet film wa6 dried by passing the coated laminate through a high velocity air oven.
8 The dwell time for the film in the oven was 11 seconds and the oven temperature was 400 degreea Fahrenheit (204C). A second, thin layer 10 of clear, wet film of coating composition was applied in the same -manner directly over the resulting dry film from the first layer of 12 coating composition. The second layer was dried in the same manner as the first layer.
14 The re~ulting clear, dried film had a total maximum dry film thickness of about 0.8 mils. The film cratered severely.

Example 8 -~

Parts by weight 20 Ingre~ie~ts (grams) 22 Dispersion of Ex5ample 1 100.00 --24 28 percent ammonia water 4 50 -~
SURFYNOL 4406 0.80 26 AEROSOL OT 757 1.00 TEGO GLIDE 1008 0.30 28 ethylene glycol monophenol ether 8.10 deionized water 20.00 32 (5) This defoamer is commercially available from TEGO Chemie. It is an oil in water emulsion of a hydrophobic polysiloxane polyether 34 copolymer.
36 (6) This is an ethoxylated tetramethyl decyndiol from Air Products.
38 (7) Sodium dioctyl sulfosuccinate from American Cyanamid.
40 (8) This mar resistance and flow additive from TEGO Chemie is a polysiloxane polyether copolymer.

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This composition was applied as has been deta~led above in 2 Example 7.
The resultant clear, dry fllm was te~ted for solvent 4 resistance and water resi~tance accordlng to the tests described herein. The film had an acetone resistance of 1 minute and a water 6 resistance in excess of 10 minutes.

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Claims

1. An anionic emulsifier-free, aqueous dispersion comprising an amine-containing polymer in combination with an acid-functional polymeric dispersant neutralized by a volatile amine wherein amino groups from said amine-containing polymer and acid groups from said acid-functional polymeric dispersant are present in relative amounts sufficient such that vaporization of said volatile amine from a wet 1.0 mil thick film from said dispersion, devoid of any external crosslinking agent, drawn down on a paper substrate and subjected to a predetermined temperature for a period of time, will result in salt formation between amino groups from said amine-containing polymer and acid groups from said acid-functional polymeric dispersant sufficient to provide a dry, organic solvent-resistant and water-resistant, film.

2. The aqueous dispersion of claim 1 wherein salt formation between amino groups from said amine-containing polymer and acid groups from said acid-functional polymeric dispersant provides said dry film which exhibits an acetone resistance of at least one minute and a water resistance of at least two minutes.

3. The aqueous dispersion of claim 1 wherein amino groups from said amine-containing polymer and acid groups from said acid-functional polymeric dispersant are present in relative amounts sufficient to provide a ratio of equivalents of said amino groups to equivalents of said acid groups in a range of from 0.15:1.0 to 1.0:1Ø

4. The anionic emulsifier-free, aqueous dispersion of claim 1 made by a two stage method comprising: in a first stage, (1) forming a first mixture of polymerizable monomers comprising by weight from 5.0 to 85 percent of an ethylenically unsaturated carboxylic acid or anhydride and from 15 to 95 percent of at least one copolymerizable ethylenically unsaturated monomer different from said carboxylic acid or anhydride, (2) polymerizing said mixture in the presence of a polymerization initiator, a suitable solvent, and optionally a molecular weight regulator to form a polymeric dispersant having a weight average molecular weight of from about 500 to about 100,000, (3) neutralizing said polymeric dispersant with a water-soluble, volatile amine to an extent required to make said polymeric dispersant water-dispersible or water-soluble, and (4) forming a dispersion or solution of said polymeric dispersant in water;
and in a second stage, (5) forming a second mixture of polymerizable monomers comprising by weight from 8.0 to 50 percent of an ethylenically unsaturated monoamine, said monoamine being present in said second mixture in an amount sufficient to provide a ratio of equivalents of amine groups from said monoamine to equivalents of carboxyl groups from said polymeric dispersant in a range of from 0.15:1.0 to 1.0:1.0, and from 50 to 92 percent of at least one copolymerizable ethylenically unsaturated monomer different from said monoamine, (6) combining said second mixture of polymerizable monomers and a polymerization initiator with said dispersion or solution produced in step (4), said second mixture of polymerizable monomers being present in an amount by weight to provide from about 40 to about 95 percent of the total weight of said first and second mixtures of polymerizable monomers, and (7) heating the combined mixture so formed to effect polymerization and produce said aqueous dispersion product.

5. The anionic emulsifier-free, aqueous dispersion of claim 9 wherein said second mixture of polymerizable monomers comprises by weight from 1 to 10 percent of a copolymerizable ethylenically unsaturated monomer having one 1,2-epoxy group.

6. The anionic emulsifier-free, aqueous dispersion of claim 9 wherein said second mixture of polymerizable monomers comprises by weight from 50 to 92 percent of one or more copolymerizable ethylenically unsaturated monomers selected from the group consisting of alkyl acrylates, alkyl methacrylates, vinyl aromatic hydrocarbons and mixtures thereof.

7. The anionic emulsifier-free, aqueous dispersion of claim 9 wherein said second mixture of polymerizable monomers comprises by weight from 1 to 10 percent of a copolymerizable ethylenically unsaturated monomer having one 1,2-epoxy group and from 40 to 91 percent of one or more copolymerizable ethylenically unsaturated monomers selected from the group consisting of alkyl acrylates, alkyl methacrylates, vinyl aromatic hydrocarbons and mixtures thereof.

8. The invention or inventions substnatially as herein described and with reference to any of the preceding claims.