SYNTHESIS OF AQUEOUS, ANIONIC, AMINO ACRYLATE POLYMERS

Background of the Invention

This invention relates to synthesis of amino acrylate polymers in water.

Acrylate polymers with amine functionality have various uses, particularly in coating compositions in which they may be crosslinked by means of polyisocyanate compositions. Since water based coatings are often preferred over organic solvent based coatings for the sake of environmental considerations, it is desirable to provide waterborne polymers that contain groups that are reactive with crosslinking agents such as polyisocyanates.

In U.S. Patent No. 5,225,505 there is disclosed amino acrylate polymers produced by emulsion polymerization in water. This patent teaches that it is necessary to include acrylic acid as one ofthe monomers for the polymerization. The polymeric products ofthe procedure disclosed in that patent have been found to be unsuitable for use in coating compositions. The deficiencies are demonstrated in a replicated example set forth herein.

In commonly owned, copending U.S. Patent Application Serial No. 08/357,488 filed December 16, 1994, there is disclosed and claimed two-component waterborne coating compositions based on cationic amino-acrylate dispersions and isocyanates that are relatively free from side reactions with water and which react to form polyureas. The cationic polymers are dispersed into water by neutralization with an acid, with the result that the coating compositions have pH below 7.0. These compositions are satisfactory for use on metals if applied over a previously applied primer coating. For use in direct contact with a metal substrate, however, coatings having pH below 7.0 have the drawback of promoting corrosion ofthe substrate. It would be desirable to have coatings ofthe type disclosed in the aforesaid patent application that have pH greater than 7.0, thereby rendering them useful for direct application onto metal substrates. Anionic amino acrylates would be useful for this purpose.

It was disclosed in U.S. Patent No. 5,075,370 that it is possible to produce aqueous, two-component polyurethane coating compositions by using neutralized, acid group-containing polyhydroxy polymers, i.e. polyhydroxypolyacrylates, as dispersing agents for polyisocyanates containing free isocyanate groups. The polyisocyanates containing free isocyanate groups are emulsified in the aqueous, anionic polymer solution or dispersion. The coating compositions according to that patent are said to have a pot life of several hours and cure by way of isocyanate/hydroxyl group reaction to form polyurethane linkages.

Summary of the Invention

The present invention is directed to aqueous, anionic amino polymers that are the polymerization products of olefinically unsaturated compounds, including compounds containing primary amine groups and or secondary amine groups. Preferably, the amino polymer is an amino acrylate.

The amino polymers ofthe present invention are synthesized in water in the presence of an emulsifier. Neutralization of amine groups with acid is not involved. Accordingly, the dispersed polymer product has pH greater than 7.0. Furthermore, the amino polymers ofthe present invention do not require acrylic acid to be included among the copolymerization monomers; preferably there is no deliberate addition of acid group containing monomers.

Important to the ability to synthesize the amino polymers ofthe present invention in water is the use of azo type initiators having carboxy functionality to initiate free radical polymerization ofthe monomers that constitute the amino polymers. The carboxy functionality is neutralized with a base to render the initiator soluble in water.

Following the procedures ofthe present invention, it has been found that a substantially cleaner polymerization is attainable than with prior art methods.

Detailed Description

The amino polymer is formed from olefinically unsaturated monomers containing primary and/or secondary amino groups. These amino groups serve as curing sites for reaction with the polyisocyanate to form urea linkages. Optionally, the amino polymers may also include hydroxyl groups, which upon curing with the isocyanate groups form urethane linkages. The amino group-containing polymers have a number average molecular weight (M _n ), as determined by gel permeation chromatography, of about 500 to 50,000, preferably about 1,000 to 10,000. The amine content ofthe amino polymer is preferably 0.05 to 2.70 milliequivalents per gram, most preferably 0.25 to 1.62 milliequivalents per gram. The amino polymer component ofthe coating compositions ofthe present invention are provided in an aqueous medium in amounts of 10 to 50 percent by weight resin solids, preferably 20 to 40 percent by weight, and has a pH value of 7.0 to 10 preferably 7.5 to 9.5. In principle, suitable amino comonomers are any olefinically unsaturated, polymerizable compounds which contain at least one primary or secondary amino group, e.g.: amino acrylates and amino methacrylates such as tert- butylaminoethyl methacrylate or meta-isopropenyl-α,α-dimethylbenzylamine. Amino groups can also be obtained by the reaction of acid polymers with aziridines such as ethylene imine, or by the reaction of epoxy and blocked ketimines, as well as other techniques known for adding amine functionality to polymers.

Monomers containing hydroxyl groups are not required in the present invention, but when used, may be included in the monomer mixture in such quantities that the hydroxyl group-containing monomers are used in quantities of about 0 to 30 percent by weight, preferably 0 to 10 percent by weight based on the total weight of monomers used to copolymerize the amino polymer.

Suitable monomers containing hydroxyl groups include, in particular, hydroxyalkyi esters of acrylic acid or methacrylic acid preferably containing 2 to 4 carbon atoms in the alkyl radical such as 2-hydroxyethyl acrylate or methacrylate, 2- or 3 -hydroxypropyl acrylate or methacrylate, the isomeric hydroxybutyl acrylates or methacrylates and mixtures of such monomers.

The third group of olefinically unsaturated monomers which may be used for the production ofthe amino polymers are olefinically unsaturated compounds which contain neither amino nor hydroxyl groups. These compounds include esters of acrylic acid or methacrylic acid containing from 1 to 18, preferably from 1 to 8, carbon atoms in the alcohol radical, such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-stearyl acrylate, and tertiary amine containing acrylates or methacrylates, and the methacrylates corresponding to these acrylates. Also included are styrene, alkyl substituted styrenes, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl stearate and mixtures of such monomers. Optionally, polyfunctional materials may be included, such as ethylene glycol dimethacrylate or allyl methacrylate. The monomers of this third group are used in quantities of 50 to 90 percent by weight, preferably about 40 to 80 percent by weight, based on the total weight ofthe monomers used.

The amino polymers are synthesized in water in the presence of an emulsifier. Details of such a polymerization process are well known to those of skill in the art. A novel feature ofthe polymerization is the selection of initiators. The polymerization reaction is free radically initiated when the monomer mixture is added together with an initiator mixture over a period of about 1 to 10 hours, preferably about 3 to 6 hours, at reaction temperature. Thereafter, more initiator may optionally be added to take the polymerization to a conversion of at least 99 percent.

Emulsifiers suitable for use in the polymerization include anionic, nonionic, and amphoteric (if non-ionic) emulsifiers. Many such emulsifiers are commercially available, several of which are disclosed in the examples herein.

The choice ofthe initiator compound used in the polymerization is important in the present invention. To attain the results of the present invention, azo type initiators which have carboxy groups are used. An initiator of this type is 4,4'- azobis(4-cyanovaleric acid), commercially available as "V-501" initiator from Wako Chemicals USA, Inc. The initiators are used in quantities of about 0.05 to 10 percent by weight, based on the total quantity of monomers. In general, the polymerization reaction takes place at temperatures in the range previously set forth, preferably at a

temperature of about 50 to 100 °C under atmospheric pressure. The exact polymerization temperature is determined by the initiator used.

The molecular weight ofthe polymers may be regulated by standard regulators such as n-dodecylmercaptan, diisopropyl xanthogene disulfide, di- (methylene-trimethylolpropane)-xanthogene disulfide and thioglycol. They may be added in quantities of up to about 10 percent by weight, based on the monomer mixture.

The coating compositions according to the invention thus obtained are suitable for virtually any applications where high performance is desired. They are particularly useful for coating of metal surfaces and various plastic surfaces.

The invention is further illustrated but is not intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified.

EXAMPLE 1

The following initial charge and feeds were used in the preparation of aqueous secondary amine functional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge

Deionized water 600.0 ABEX EP-120 ¹ 64.2

Fee l n-Butyl acrylate 300.8

Methyl methacrylate 179.2 Tert-butylaminoethyl methacrylate 160.0

Feed 2

V-501 ² initiator 16.0

Aqueous ammonia (29.7 %) 7.0 Deionized water 296.6

Ammonium salt of sulfated nonylphenoxypoly(ethyleneoxy) ethanol (30 % active), available from Rhone-Poulenc, USA.

² 4,4'-Azobis(4-cyanovaleric acid), available from Wako Chemicals USA, Inc.

The initial charge was heated to a temperature of 80°C with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 40 grams of Feed 1 were added to the reaction vessel and held about 5 minutes for regaining the temperature, followed by the addition of 40 grams of Feed 2 and holding the reaction mixture temperature at 80°C. for 30 minutes. Then the temperature was raised to 85°C, and the reaction mixture was held for 30 minutes at this temperature. The remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction mixture temperature at about 85°C. At the completion of the additions, the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 40.6 percent determined at 110°C. for one hour and a pH of 9.27.

EXAMPLE 2

The following initial charge and feeds were used in the preparation of aqueous secondary amine functional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge

Deionized water 300.0

ABEX EP-120 19.2

Feed 1 n-Butyl acrylate 96.0

Methyl methacrylate 160.0

Tert-butylaminoethyl methacrylate 64.0

Feed 2

V-501 8.0

Aqueous ammonia (29.7 %) 3.5

Deionized water 148.3

The initial charge was heated to a temperature of 85°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 25 grams of Feed 1 was added to the reaction vessel and held about 10 minutes for regaining the temperature, followed by the addition of 25 grams of Feed 2 and holding the reaction mixture temperature at 85°C. for 30 minutes. Then the remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction mixture temperature at about 85°C. At the completion ofthe additions, the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 40.2 percent determined at 110°C. for one hour and a pH of 8.8.

EXAMPLE 3 (COMPARATIVE)

For the purpose of comparison, a secondary amine functional polymer was prepared in the same manner as disclosed in Example 5 of U.S. Patent No. 5,225,505. In a reactor a mixture of 54 grams of methyl methacrylate, 50 grams of tert-butylaminoethyl methacrylate, 94 grams of n-butyl acrylate and 2 grams of acrylic acid was polymerized batchwise in an emulsion in 300 grams of deionized water in the presence of 0.7 grams of ammonium persulphate and 0.7 grams of sodium metabisulphite as initiators, and in the presence of 20 grams of AB EX- 120 (30 percent active) as surfactant. The polymerization was carried out at 72°C for about 3 hours, resulting in an unstable dispersion. An exotherm was observed after further addition of 0.7 grams of ammonium persulphate dissolved in 10 grams of deionized water and 0.7 grams of sodium metabisulphite dissolved in 10 grams of deionized water and raising the reaction temperature to 85°C. The reaction mixture was held about one hour at 85°C. The resultant dispersion was full of grit, and after filtration gave a dispersion having 31.4 percent solids determined at 110°C for one hour. The product was unsuitable for use in a coating composition.

The aqueous anionic amino polymers ofthe present invention may constitute film forming resins in coating compositions when formulated with curing agents such as polyisocyanates or polyepoxides. Aqueous, polyisocyanate-cured,

anionic coatings containing the amino polymers ofthe present invention are the subject matter of commonly owned U.S. Patent Application Serial No. titled "Aqueous, Anionic, Amino Acrylate Coating Compositions" filed on even date herewith by Suryya Das, Soner Kilic, Robert E. Jennings, and James A. Claar. To prepare the coating compositions, the polyisocyanate component is emulsified in the aqueous amino group-containing polymer component. The dissolved or dispersed polymer simultaneously serves as an emulsifier for the polyisocyanate added. Optionally, dispersion ofthe polyisocyanate component may be assisted by a separate surfactant. The polyisocyanate component may be any polyisocyanate containing aliphatically, cycloaliphatically, araliphatically and/or aromatically bound isocyanate groups which are liquid at room temperature. The polyisocyanate component may optionally be modified to be water dispersible or soluble. The polyisocyanate component is preferably a polyisocyanate or polyisocyanate mixture exclusively containing aliphatically and/or cycloaliphatically bound isocyanate groups and having an average NCO functionality of about 2.0 to 5.0.

Suitable polyisocyanates include those containing aromatically or (cyclo)aliphatically bound isocyanate groups, (cyclo)aliphatic polyisocyanates being particularly preferred. Particularly suitable are polyisocyanates based on hexamethylene diisocyanate, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cydohexane (IPDI) and/or bis-(isocyanatocyclohexyl)-methane, particularly those based on hexamethylene diisocyanate. Other suitable polyisocyanates based on these diisocyanates may include the biuret, urethane, uretdione and/or isocyanurate derivatives of these diisocyanates which, after their production, have been freed in the known manner, preferably by distillation, from excess starting diisocyanate to a residual content of less than 0.5 percent by weight. Aliphatic polyisocyanates for use in accordance with the invention include biuret polyisocyanates based on hexamethylene which are based on mixtures of N,N',N"-tris-(6- isocyanatohexyl)biuret with small quantities of its higher homologs. These polyisocyanates may be obtained by the processes according to U.S. Pat. Nos. 3,124,605; 3,358,010; 3,903,126; 3,903,127 or 3,976,622. Also preferred are the

cyclic trimers of hexamethylene diisocyanate corresponding to the criteria mentioned above which may be obtained in accordance with U.S. Pat. No. 4,324,879 and which are based on N,N'N"-tris-(6-isocyanatohexyl)-isocyanurate in admixture with small quantities of its higher homologs.

The following Examples A, B, and C are coating compositions formulated with the anionic amino polymers of Examples 1 and 2. The pH of each of the compositions was greater than 7.0.

EXAMPLE A

Ingredients Parts by Weight

Grind Paste

Deionized water 8.330 TAMOL 850 ³ 0.500 PGNP- 15 Surfactant ^' 0.574

TRITON GR7M 5 0.260 PLURONIC P-10: 0.056 DEE FO 97-3 ⁷ 0.121 BUSAN 11-M1 ⁸ 2.120 ZB-325 ⁹ 3.571

NYAD 1250 10 1.228 TI-PURE R-902-38 ' 3.380 BAYFERROX 3910 12 0.444 BAYFERROX Black 318M 13 0.712 MICROTALC MP-12-50 ^l4 8.288 BARIMITE XF 15 3.287 ATTAGEL 50 16 0.223 TEXANOL " 0.245 Deionized water 4.457

DSX-1514 1 ¹ 8 ⁰ thickener 0.243 Let-down,

19 n-Propanol 0.122 Amino acrylate ofExample 1 27.158

EXXATE 900 2 ^" 0 ^" 2.732 Isocyanate

Anionic isocyanate 21

3.346 EXXATE 900 0.549 Deionized water 28.054

EXAMPLE B

Ingredients Parts by Weight

Grind Paste

Deionized water 13.456

TAMOL 850 0.527

PGNP-15 SURFACTANT 0.502 Deionized water 4.77

TRITON GR-7M 0.126

PLURONIC P-103 0.110

DEE FO 97-3 0.140

MOLYWHITE 212 ²² 2.324 ZB-325 1.163

SICORIN RZ ²³ 0.079

MICROTALC MP- 12-50 13.764

BARIMITE XF 5.459

TI-PURE R902-38 2.389 BUFF TiO ₂ ²⁴ 1.183

RAVEN 410 ²⁵ 0.008

BAYFERROX MOM ²⁶ 0.008

BAYFERROX 3910 0.276

BAYFERROX BLACK 318M 0.440 ATTAGEL 50 0.117

TEXANOL 0.279

DSX-1514 thickener 0.063

Let-down n-Propanol 0.031 Sodium dichromate ²⁷ 0.210

Amino acrylate of Example 2 35.322

EXXATE 900 3.532

Deionized water 8.475

SANTICIZER 160 ²⁸ 1.048 Isocvanate

Emulsifier 0.766

Isophorone diisocyanate 1.073

Deionized water 6.500

EXAMPLE C

Ingredients Parts by Weight

Grind Paste

Deionized water 7.021

TAMOL 850 0.527

PGNP-15 Surfactant 0.669

TRITON GR-7M 0.421 DEE FO 97-3 0.118

RAVEN 410 0.156

TI-PURE R902-38 1.872

BUFF TT.O2 7.489

MICROTALC MP- 12-50 10.648 BARIMITE XF 4.212

SHIELDEX ³¹ 4.088

Deionized water 9.819

Sodium dichromate 0.234 Let-down Amino acrylate of Example 2 35.212

EXXATE 900 4.808

Deionized water 8.449 Isocyanate

DESMODUR N 3400 32 3.049 Emulsifier 33 0.829 SILQUEST Y-9669 34 0.379

TAMOL 850 - Aqueous pigment dispersant available from Union Carbide Chemicals & Plastic Company, Industrial Chemicals Div., Danbury, Connecticut.

PGNP-15 - Polyproxylated nonyl phenol, nonionic surfactant produced by PPG Industries, Pittsburgh, Pennsylvania.

TRITON GR-7M - Anionic surfactant available form Union Carbide Chemicals & Plastic Company, Industrial Chemicals Div., Danbury, Connecticut.

⁶ PLURONIC P-103 - Nonionic surfactant available from BASF Corporation, Chemicals Div., Parsippany, New Jersey.

7 (R)

DEE FO 97-3 - Defoamer available form Ultra Additives, Inc., Paterson, New Jersey.

BUS AN 11-M1 - Barium metaborate available from Buckman Laboratories, Inc., Memphis, Tennessee.

ZB-325 - Zinc borate available from Polymer Additives Group, Southiield,

Michigan.

NYAD 1250 - Wollastonite available from Nyco Minerals Inc., Willsboro, New York.

TI-PURE R902-38 - Titanium dioxide pigment available from E.I. du Pont de Nemours & Co., Wilmington, Delaware.

¹² BAYFERROX 3910 - Yellow iron oxide pigment available from Bayer

Corporation, Pittsburgh, Pennsylvania.

¹³ BAYFERROX Black 318M - Black iron oxide pigment available from

Bayer Corporation, Pittsburgh, Pennsylvania.

MICROTALC MP- 12-50 - Magnesium silicate hydrate available from Whittaker, Clark, & Daniel Inc., South Plainfield, New Jersey.

¹⁵ BARIMITE XF ^® - Barium sulfate available form Cyprus Industrial Mineral Co., Cartersville, Georgia.

¹⁶ ATTAGEL 50 - Attapulgite available from Engelhard Corporation, New

Jersey.

^π TEXANOL - Solvent available from Eastman Chemical Products, Inc.,

Kingsport, Tennessee.

¹⁸ DSX-1514 ^® - Thickener available from Henkel, Kankakee, Illinois.

n-Propanol - Solvent available from Eastman Chemical Products, Inc.,

Kingsport, Tennessee.

²⁰ EXXATE ^® 900 - Co alkyl acetate solvent available from Exxon Chemical Co., Houston, Texas.

21 Anionic isocyanate made by the following reaction. Isophorone diisocyanate (318.2 grams, 2.88 NCO equivalents), DESMODUR W (188.6 grams, 1.44 NCO equivalents), and propoxylated 1 ,4-butanediol sodium sulfonate (244.7 grams, 1.03 OH equivalents) were placed into a one liter, four-neck, round bottom flask. The flask was heated to 90°C and a nitrogen blanket was applied throughout the reaction.. The flask was kept at 90°C until the isocyanate equivalent weight reached 225. The propoxylated 1 ,4-butanediol sodium sulfonate was prepared in accordance with British Patent No. 1,447,612 by hydro-sulfonation ofthe product of the reaction of 1 ,4-butenediol (1 mole) with propylene oxide (6 moles).

²² MOL Y WHITE 212 - Corrosion protective pigment available from Sherwin Williams Chemicals, Coffeyville, Kansas

²³ SICORTN RZ - Corrosion protective pigment available from BASF Corp., 5 Rensselaer, New York.

²⁴ BUFF TiO2 - Hiding pigment available from Hitox Corporation of America, Corpus Christi, Texas.

l o ²⁵ RAVEN ^® 410 - Carbon black pigment available from Cities Service Co.,

Columbian Div., Akron, Ohio.

²⁶ BAYFERROX 140M - Red iron oxide pigment available from Bayer Corporation, Pittsburgh, Pennsylvania. 15

Sodium dichromate - Flash rust inhibitor available from Fisher Scientific Co., Chemical Mfg. Div., Fair Lawn, New Jersey.

²⁸ SANTICIZER 160 - Butyl benzyl phthalate available from Monsanto , St. 0 Louis, Missouri.

Emulsifier - A nonionic surfactant containing 62.3% T-l 890 (an IPDI isocyanurate from Huls America, Inc., Piscataway, NJ 08855), 28.8% CARBOWAX 750ME (a monofunctional polyether surfactant available from Union Carbide 25 Chemicals & Plastics Co., Inc., S. Charleston, WV 25303), 16.9% diethylamine (secondary amine available from Union Carbide, S. Charleston, WV) prepared in methyl ethyl ketone and PROGLYDE DMM (solvent, dipropylene glycol dimethoxyether, available from Dow Chemical U.S.A., Chemicals and Performance Products Dept., 100 Larkin Ctr., Midland, MI 48674).

30

Isophorone diisocyanate - Monomeric, aliphatic isocyanate available from Bayer Corporation, Pittsburgh, PA.

SHIELDEX - Corrosion protective pigment available from Grace, Davison 35 Chemical Div., Baltimore, MD.

DESMODUR N 3400 - A trimer isocyanate available from Bayer Corporation, Pittsburgh, Pennsylvania.

40 ³³ Emulsifier - A nonionic surfactant containing 75% T-l 890 (an IPDI isocyanurate available from Huls America, Inc., Piscataway, NJ 08855) and 25% CARBOWAX 750ME (a monofunctional polyether surfactant available from Union Carbide Chemicals & Plastic Co., Inc., Solvents & Coatings Materials Div., S. Charleston, WV 25303), prepared in methyl ethyl ketone and PROGLYDE DMM

45 (dipropyleneglycol dimethoxy ether, available from Dow Chemical Co., Midland, MI).

SILQUEST ^® Y-9669 - Amino-silane available from OSi Specialties, Inc., Sistersville, West Virginia.

The coating compositions of Examples A through C were prepared in the following manner. In a grinding vessel under high speed agitation with a Cowles blade, the pigments were sifted into the other components ofthe grind paste (except the thickener). After stirring for 5 minutes the Cowles blade was replaced with an Impeller blade, and zircoa beads were then added. This mix was stirred at high speed for one hour, after which the beads were separated from the grind paste. The thickener (DSX- 1514) was then added to the grind paste and stirred at high speed for five minutes, after which the grind paste was diluted with the let-down ingredients. The isocyanate portions ofthe Examples were prepared and added to the other ingredients as described below. In Example A, the anionic isocyanate was diluted with EXXATE 900 to 70% solids, further diluted to 35% solids with deionized water, and then immediately stirred with moderate agitation into the container holding the remainder ofthe ingredients.

In Example B, 75% isophorone diisocyanate was blended with 25% of the isocyanate emulsifier. This combination was stirred with moderate agitation into the container holding the remainder ofthe ingredients.

In Example C, the isocyanate emulsifier was blended with SILQUEST Y-9669 at 1 part isocyanate to 1 part amine by equivalents. After a 24 hour induction, 25% ofthe blend was mixed with DESMODUR N 3400 isocyanate. This isocyanate combination was stirred with moderate agitation into the container holding the remainder ofthe ingredients.

Each ofthe coating formulations of Examples A, B, and C was tested for performance by application onto a substrate prepared as follows. The substrate for each example was 32 gauge, unpolished, cold rolled steel (available from Advanced Coating Technologies, Inc., Hillsdale, Michigan, as code: APR10288) sanded with P180 grit sandpaper (Pl 80-216U, Production RN FRE-CUT, Paper A weight, open coat, available from 3M, St. Paul, MN). The substrate was washed with Acryli-Clean

or DX-330 (available from PPG Industries, Pittsburgh, PA as a wax and grease remover) and wiped with a lintless tissue (available from Scott Paper Company, Philadelphia, Pennsylvania, as Scott Precision Wipes).

After at least a 24 hour induction each ofthe compositions ofthe examples was applied by air-atomized spray at 45 psi. over the previously prepared substrates. Each coated substrate was air-dried under ambient conditions for 1 hour. Then each was dry-sanded with P400 grit sandpaper (P400-213Q, Imperial Wetordry production paper, "A" weight, available from 3M, St. Paul, Minnesota) immediately and, if necessary, at every succeeding hour interval. The time at which the example coating was observed to be sandable, i.e., when it did not foul the sandpaper, was taken to be the minimum required time after application until sandable.

Immediately after each spray application, the remaining portion of each example composition, approximately 85 to 100 grams, was sealed in a 1/2 pint container. Each sample container was stored at room temperature for two months, reopened, and observed for fluidity at one month intervals.

Evaluation ofthe adhesion ofthe coating of each example to the substrate was performed by applying masking tape (2 inch, "232 Masking Tape" available from 3M, St. Paul Minnesota) after a 1 hour cure and dry time and then peeling it off. Additional adhesion testing was performed in accordance with method set forth in ASTM D3359, Method B, whereby the example coating was scribed with a Gardner Cross Cut Tester, Model P-A-T, fitted with a PA-2056 blade, both available from Gardco, Pompano Beach, Florida. The scribed coatings were subjected to tape pulling using Permacel 99 tape after the example coatings were dried and cured for 96 hours, and again after an additional 96 hours during which they were exposed to 100 degrees F and 100% humidity.

The results of each of these performance tests are set forth in Table 1.

TABLE 1

EXAMPLE EXAMPLE EXAMPLE A B C

SANDING l hr. Pass Fail Pass

2 hr. N.A. Pass N.A.

3 hr. N.A. N.A. N.A.

ADHESION

1 hr. masking Pass Pass Pass

96 hr. Pass, 100% Pass, 100% Pass, 99%

96 hr. plus 96 hr. Pass, 100% Pass, 95% Fail, 90% humidity exposure

FLUIDITY

1 month Pass Pass Pass

2 month Pass Pass Pass

N.A., or "not applicable," indicated no further testing was needed.

A "fail" rating under SANDING indicated fouling ofthe sandpaper due to embedment of the coating into the sandpaper's grit.

A "fail" rating under ADHESION indicated a less than 95% adhesion ofthe example coating over the substrate.

A "fail" rating under FLUIDITY indicated an example coating with an unsprayable viscosity, even when diluted with water.

The following examples illustrate coating embodiments wherein the coating composition is supplied as two separate packages for the amino polymer and the polyisocyanate. Examples 4 and 5 relate to amino polymers employed in the coating formulations of Examples D and E.

EXAMPLE 4

The foUowing initial charge and feeds were used in the preparation of aqueous secondary amine functional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge Deionized water 600.0

ETHOMEEN C/25* 19.2

Feed l n-Butyl acrylate 300.8 Methyl methacrylate 179.2

Tert-butylaminoethyl methacrylate 160.0

Feed 2

V-501 initiator 16.0 Aqueous ammonia (29.7 %>) 7.0

Deionized water 296.6

* Polyoxyethylene(15)cocoamine, available from Akzo Chemie America.

The polymerization was conducted under the same procedure as described above in Example 1. The product was filtered to yield a dispersion with a resin content of 41.5 percent determined at 110°C. for one hour and a pH of 9.33.

EXAMPLE 5 The following initial charge and feeds were used in the preparation of aqueous secondary amine functional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge

Deionized water 300.0

ABEX EP-120 ^* 19.2

Feed l n-Butyl acrylate 96.0

Methyl methacrylate 160.0

Tert-butylaminoethyl methacrylate 64.0

eed 2

V-501 8.0

Aqueous ammonia (29.7 %) 3.5 Deionized water 148.3

Ammonium salt of sulfated nonylphenoxypoly(ethyleneoxy) ethanol (30 % active), available from Rhone-Poulenc, USA.

The initial charge was heated to a temperature of 85°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 25 grams of Feed 1 was added to the reaction vessel and held about 10 minutes for regaining the temperature, followed by the addition of 25 grams of Feed 2 and holding the reaction mixture temperature at 85°C. for 30 minutes. Then the remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3-hour period while maintaining the reaction mixture temperature at about 85°C. At the completion of addition the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 40.2 percent determined at 110°C. for one hour and a pH of 8.8.

EXAMPLE D

Ingredients Parts by Weight

Package 1

Deionized water 13.048

TAMOL 850 0.605 PGNP- 15 Surfactant 0.166

SOLSPERSE 27000 ³⁵ 0.451

TRITON GR-7M 0.309

DEE FO 97-3 0.077

NALZIN 2 ³⁶ 7.064 NY AD 1250 3.531

MICROTALC MP- 12-50 10.008

BARIMITE XF 3.959

TI-PURE R902-38 4.179

BAYFERROX 3910 0.550

BAYFERROX BLACK 318M 0.880

TEXANOL 0.165

DSX-1514 0.066

n-Propanol 0.033

Sodium dichromate 0.103

Amino acrylate of Example 4 29.665

EXXATE 900 4.121

Deionized water 16.600

Package 2 E Enmulsifier ³⁷ 1.105 DESMODUR N 3400 3.315

EXAMPLE E

Ingredients Parts by Weight

Package 1

Deionized water 6.003

TAMOL 850 0.450

PGNP- 15 Surfactant 0.572 TRITON GR-7M 0.360

DEE FO 97-3 0.100

SHIELDEX 3.362

MICROTALC MP- 12-50 9.104

BARIMITE XF 3.602 TI-PURE R902-38 1.601

BUFF TiO ₂ 6.403

RAVEN 410 0.133

Strontium chromate ³⁸ 0.300

Deionized water 8.028 DSX-1514 thickener 0.200

n-Propanol 0.100

Amino acrylate ofExample 5 30.105

EXXATE 900 5.002 Deionized water 21.094

Package 2 E Emmuullssiififieerr ³⁷ 0.870 DESMODUR N 3400 2.611

³⁵ SOLSPERSE ^® 27000 - Hyperdispersant available from ICI Surfactants, Wilmington, Delaware.

NALZI T 2 - Anticorrosive pigment available from Rheox, Inc., P.O. Box 700, Hightstown, NJ.

³⁷ Emulsifier - A nonionic surfactant containing 33.3% T-l 890 (an IPDI isocyanurate available from Huls America, Piscataway, NJ 08855.), 11.1% CARBOWAX ^® 750ME, 55.6% Solvactant ^® DMH-7 (a monofunctional polyether surfactant and a nonionic surfactant, respectively, both available from Union Carbide Chemicals and Plastics Co., Inc., Danbury, Connecticut.

Strontium chromate - Corrosion inhibitive pigment available from Cookson

Pigments.

The coating compositions of Examples A and B were prepared as two- package compositions with the amino acrylate, pigments, and additives in one package (Package 1 ) and the isocyanate and isocyanate emulsifier in a second package (Package 2). In an appropriate grinding vessel and under high speed agitation with a Cowles blade, Package 1 was prepared by mixing the pigments into a surfactant, defoamer, and water mix. After stirring for 5 minutes the Cowles blade was replaced with an Impeller blade, and zircoa beads were then added. This mix was stirred at high speed for one hour, after which the beads were separated from the grind paste. The thickener (DSX-1514) was added to the grind paste and stirred at high speed for five minutes. An appropriate amount of this grind paste was then added to the amino acrylate and water.

Each of the coating formulations of Examples D and E was tested for performance by application onto a substrate prepared in the same manner as described above in connection with Examples A, B, and C. Before spray application, Package 2 was added to Package 1 for each example, with moderate and constant agitation. Each ofthe compositions ofthe examples was applied by air-atomized spray at 45 psi. over the previously prepared substrates. Each coated substrate was air-dried under ambient conditions for 1 hour. Then each was dry-sanded with P400 grit sandpaper (P400-213Q, Imperial Wetordry production paper, "A" weight, available form 3M, St. Paul, Minnesota) immediately and, if necessary, at every succeeding hour interval. The time at which the example

coating was observed to be sandable, i.e., when it did not foul the sandpaper, was taken to be the minimum required time after application until sandable.

Each two-component coating composition example was additionally subjected to a test for gassing potential. Immediately after each spray application, the remaining portion of each blended composition, approximately 85 to 100 grams, was sealed in a 1/2 pint container. Each sample container was opened at 1 hour intervals and was evaluated for gas-pressure buildup by listening for an audible hissing of pressurized gas, an audible popping ofthe lid, or observing bubbling or foaming of the wet sample.

Evaluation of adhesion of each coating to the substrate was performed by the same technique described above in connection with Examples A, B, and C.

The results of each of these performance tests for Examples D and E are set forth in Table 2.

TABLE 2

EXAMPLE D EXAMPLE E

SANDING l hr Fail Pass

2 hr Pass N.A

3 hr N A N.A

ADHESION

1 hr masking Pass, 100% Pass, 100%

96 hr Pass. 100% Pass, 100%

96 hr plus 96 hr humidity exposure Pass, 100% Pass, 100%

GASSING l hr Pass Pass

2 hr Pass Pass

24 hr Pass Pass

N.A , or "not applicable," indicated no further testing was needed

A "fail" rating under SANDING indicated fouling ofthe sandpaper due to embedment of the coating into the sandpaper's grit

A "fail" rating under ADHESION indicated a less than 95% adhesion ofthe example coating over the substrate

A "fail" rating under GASSING indicated bubbling of the wet sample due to gas evolvement.

The following Examples 6 through 11 further illustrate embodiments of the aqueous polymerization ofthe present invention.

EXAMPLE 6

The following initial charge and feeds were used in the preparation of aqueous secondary amine f nctional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge Deionized water 600.0

ALIPAL CO-436 ¹ 33.2

Feed l n-Butyl acrylate 300.8 Methyl methacrylate 179.2

Tert-butylaminoethyl methacrylate 160.0

Feed 2

V-501 ² 16.0 Aqueous ammonia (29. 7 %) 7.0

Deionized water 296.6

Ammonium salt of ethoxylated nonyl phenol sulfate (58.0 % active), available from Rhone-Poulenc, USA.

4,4'-Azobis(4-cyanovaleric acid), available from Wako Chemicals USA,

Inc.

The initial charge was heated to a temperature of 80°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 40 Grams of Feed 1 was added to the reaction vessel and held about 5 minutes for regaining the temperature followed by the addition of 40 grams of Feed 2 and holding the reaction mixture temperature at 80°C. for 30 minutes. Then the temperature raised to 85°C. and the reaction mixture was held 30 minutes at this temperature. The remaining of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction mixture temperature at about 85°C. At the completion of addition the reaction mixture was held for 2 hours at 85°C. to complete the

polymerization. The product was filtered to yield a dispersion with a resin content of 41.6 percent determined at 110°C. for one hour and a pH of 9.31.

EXAMPLE 7 The following initial charge and feeds were used to prepare an aqueous secondary amine functional acrylic polymer using phosphate containing surfactant.

Ingredients Parts by Weight

Initial Charge

Deionized water 600.0

Surfactant solution 69.7

Feed 1 n-Butyl acrylate 300.8 Methyl methacrylate 179.2 Tert-butylaminoethyl methacrylate 160.0

Feed 2 V-501 16.0

Aqueous ammonia (29.7 %) 7.0 Deionized water 296.6

Prepared dissolving 176.7 grams of EMPHOS CS-141 (polyoxyalkylated alkylaryl phosphate ester, available from Witco Corporation) after neutralization with 24.8 grams of aqueous ammonia (29.7 %) in 444.2 grams of deionized water.

The initial charge was heated to a temperature of 85°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 40 Grams of Feed 1 was added to the reaction vessel and held about 5 minutes for regaining the temperature followed by the addition of 40 grams of Feed 2 and holding the reaction mixture temperature at 85°C. for 30 minutes. Then the remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction temperature at about 85°C. At the completion of addition the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 39.6 percent determined at 110°C. for one hour and a pH of 9.24.

EXAMPLE 8

The following initial charge and feeds were used in the preparation of aqueous acrylic polymer containing 50 percent tert-butylaminoethyl methacrylate via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge

Deionized water 226.5

ETHOMEEN C/25 14.4

Feed l n-Butyl acrylate 120.0

Methyl methacrylate 120.0

Tert-butylaminoethyl methacrylate 240.0

Feed 2 V-501 12.0

N,N-Dimethylethanol amine 7.8

Deionized water 200.0

The initial charge was heated to a temperature of 85°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 40 Grams of Feed 1 was added to the reaction vessel and held about 10 minutes for regaining the temperature followed by the addition of 40 grams of Feed 2 and holding the reaction mixture temperature at 85°C. for 30 minutes. Then the remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3-hour period while maintaining the reaction temperature at about 85°C. At the completion of addition the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 51.9 percent determined at 110°C. for one hour and a pH of 9.15.

EXAMPLE 9

The following initial charge and feeds were used in the preparation of aqueous hydroxyl and secondary amine functional acrylic polymer via emulsion polymerization technique.

Ingredients Parts by Weight

Initial Charge

Deionized water 151.5

ETHOMEEN C/25 14.4

Feed l n-Butyl acrylate 120.0

Methyl methacrylate 120.0

Tert-butylaminoethyl methacrylate 180.0

2-Hydroxyethyl methacrylate 60.0

Tert-dodecyl mercaptan 24.0

Feed 2

V-501 12.0

N,N-Dimethylethanol amine 7.8

Deionized water 125.0

The initial charge was heated to a temperature of 85°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. 40 Grams of Feed 1 was added to the reaction vessel and held about 10 minutes for regaining the temperature followed by the addition of 40 grams of Feed 2 and holding the reaction mixture temperature at 85°C. for 30 minutes. Then the remaining portions of Feed 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction temperature at about 85°C. At the completion of addition the reaction mixture was held for 2 hours at 85°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 62.5 percent determined at 110°C. for one hour and a pH of 8.84.

EXAMPLE 10

The following initial charge and feeds were used in the preparation of aqueous secondary amine functional acrylic polymer using mixed surfactants.

Ingredients Parts by Weight

Initial Charge

Deionized water 427.6

ETHOMEEN C/25 19.2

ABEX EP-120 32.0

Fee l n-Butyl acrylate 72.0

Methyl methacrylate 206.4

Tert-butylaminoethyl methacrylate 96.0

Styrene 105.6

Feed 2

V-501 12.0

N,N-Dimethylethanol amine 7.8

Deionized water 222.5

The initial charge was heated to a temperature of 90°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. The Feeds 1 and 2 were added to the reaction mixture simultaneously over a 3 -hour period while maintaining the reaction temperature at about 90°C. At the completion of addition the reaction mixture was held for 2 hours at 90°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 43.1 percent determined at 110°C. for one hour and a pH of 9.25.

EXAMPLE 11

The following initial charge and feeds were used in the preparation of aqueous secondary amine functional crosslinked acrylic polymer.

Ingredients Parts by Weight

Initial Charge

Deionized water 427.6

ABEX EP-120 19.2

Feed 1 n-Butyl acrylate 18.0

Methyl methacrylate 51.6

Tert-butylaminoethyl methacrylate 24.0

Styrene 26.4

Feed 2 n-Butyl acrylate 51.3

Methyl methacrylate 147.1

Tert-butylaminoethyl methacrylate 68.4

Styrene 75.2

Ethyleneglycoldimethacrylate 18.0

Feed 3

V-501 12.0

N,N-Dimethylethanol amine 7.8

Deionized water 222.5

ABEX EP-120 12.8

The initial charge was heated to a temperature of 90°C. with agitation in a reaction vessel suitable for aqueous emulsion polymerization. Feeding of Feed 1 and 3 was initiated at the same time. The Feed 1 was added over 45 minutes and Feed 3 was added to a 3-hour period while maintaining the reaction temperature at about 90°C. At the completion ofthe Feed 3, the Feed 2 addition was initiated and added over 2 hours and 15 minutes. At the completion ofthe Feed 2 and 3 the reaction mixture was held for 2 hours at 90°C. to complete the polymerization. The product was filtered to yield a dispersion with a resin content of 42.4 percent determined at 110°C. for one hour and a pH of9.0.

Although the invention has been described in detail for the purpose of illustrating the best mode ofthe invention, it is to be understood that such detail is solely for that purpose and that variations can be made by those skilled in the art without departing from the spirit and scope ofthe invention as defined by the claims.