MXPA98004917A - Compositions of coating, amylic acrilate, aqueous, anioni - Google Patents

Abstract

Aqueous coating compositions are described in a package or in two packages, having a pH above 7.0 which contain as binder a polyurea which is the product of a polyisocyanate and an anionic amine polymer synthesized in water from olefinic monomers unsaturated including monomers containing primary or secondary amine, the monomers being substantially free of acid groups. The polymerization of the amine polymer is carried out in the presence of an azo initiator dispersed in water by neutralization of the acid groups present in the initiator.

Description

COMPOSITIONS OF COATING, AMYLIC ACRYLIC, AQUEOUS, • ANIONIC BACKGROUND OF THE INVENTION This invention relates to aqueous coating compositions based on amine acrylate polymers. It is generally desirable to use waterborne coatings in place of organic solvent based coatings for reasons of environmental considerations. However, the use of water instead of organic solvents in coating compositions based on polyisocyanates containing free isocyanate groups has been hampered by the fact that the isocyanate groups react not only with the isocyanate-reactive groups, in the sought crosslinking reaction, but also with water. Therefore, in a composition including a polyisocyanate, isocyanate-reactive groups and water, an isocyanate / water reaction occurs with formation of urea and carbon monoxide. This reaction not only prevents the desired cross-linking of the isocyanate-reactive groups from being achieved, but also results in the formation of gas or foam in the composition due to the formation of carbon dioxide. Several attempts have been made in prior art to stabilize aqueous isocyanate compositions against undesired secondary reaction with water. U.S. Patent No. 5,225,505 discloses amine acrylate polymers produced by emulsion polymerization in water. This patent indicates that it is necessary to include acrylic acid as one of the monomers for the polymerization. The polymeric products of the process described in this patent have turned out to be unsuitable for use in coating compositions. The deficiencies are demonstrated in an example reproduced here. In U.S. Patent No. 5,075,370 it is noted that it is possible to produce two-component polyurethane aqueous coating compositions using neutralized acid-containing polyhydroxy polymers, ie, polyhydroxy polyacrylates, as dispersing agents for polyisocyanates containing free isocyanate groups. The polyisocyanates containing free isocyanate groups are emulsified in the aqueous solution or dispersion of the anionic polymer. From the coating compositions according to this patent it is said that they have a shelf life of several hours and that they are cured through the isocyanate / hydroxyl group reaction to form polyurethane bonds. In commonly owned US Patent Application Serial No. 08 / 357,488 filed December 16, 1994, water-based coating compositions having two components and based on dispersions of cationic amine acrylate and isocyanates are described and claimed. which are relatively free of secondary reactions with water and which react to form polyureas. The amine acrylate polymers are dispersed in water by neutralization with an acid, resulting in coating compositions having a pH below 7.0. These compositions are satisfactory for use on metals if they are applied over a previously applied primer coating. For use in direct contact with a metal substrate, however, coatings having a pH below 7.0 have the disadvantage of promoting substrate corrosion. It would be desirable to have coatings of the type described in the aforementioned patent application with a pH greater than 7.0, so that they would be useful in direct application to metal substrates.

SUMMARY OF THE INVENTION The present invention relates to aqueous coating compositions having a pH above 7.0 containing polyureas as the primary binder component resulting from the mixture of anionic, aqueous amine polymers, and polyisocyanates. Anionic amine polymers are the polymerization products of olefinically unsaturated compounds, which include compounds containing primary amine groups and / or secondary amine groups. Optionally, other isocyanate-reactive groups, such as hydroxyl groups, may also be present in the monomers from which the amine polymer is synthesized. Preferably, the amine polymer is an amine acrylate. The amine polymers of the present invention are polymerized in water in the presence of an emulsifier. There is no neutralization of amine groups with acid. According to this, the dispersed polymer product has a pH greater than 7.0. In addition, the aminic polymers of the present invention do not require including acrylic acid between the copolymerization monomers; preferably, there is no deliberate addition of monomers containing acid group. As a result, it has been found that a substantially cleaner polymerization can be achieved. The use of azo-type initiators having carboxy functionality to initiate the polymerization of free radicals of the monomers constituting the amino polymers is important for the ability to synthesize the aminic polymers of the present invention in water. The carboxy function of the initiator is neutralized with a base to make the initiator soluble in water. The polyisocyanate component contains polyisocyanate groups in amounts sufficient to provide an NCO / NH equivalent ratio of 0.5: 1 to 5: 1 in double package embodiments, and 0.5: 1 to 1: 1 in embodiments in a single container. If the amine polymer also includes hydroxyl groups, as is optionally allowed, these ratios refer to the NCO / (NH + OH) equivalents ratio. The polyisocyanate component is emulsified in the aqueous amine polymer component, optionally with the aid of a surfactant compound, thus initiating crosslinking through urea bonds. The composition can be supplied in two separate packages, in which case the amine polymer and isocyanate are combined only immediately before use. However, it has surprisingly been found that in some embodiments the coating can be supplied in a single package without overall gelation. Whether in the form of one or two containers, the compositions of the present invention are dried or cured, respectively, very quickly. The speed of fast drying or curing and the high pH make the use of the coating compositions very advantageous, for example as primers for direct application on metal.

DETAILED DESCRIPTION The amine polymers contained in the coatings of the present invention are synthesized by a new method described herein and which is the subject of the commonly owned US Patent Application Serial No. entitled "Synthesis of aqueous, anionic, acrylate polymers. amínico "registered on the same date as the present one by Suryya Das and Soner Kilic. Amino polymers are formed from olefinically unsaturated monomers containing primary and / or secondary amino groups. These amino groups serve as curing points for the reaction with polyisocyanate to form urea bonds. Optionally, the aminic polymers can also include hydroxyl groups which, when cured with the isocyanate groups, form urethane linkages. The amino group containing polymers have a number average molecular weight (Mn), as determined by gel permeation chromatography, of from about 500 to 50,000, preferably from about 1,000 to 10,000. The amine content of the amine polymer is preferably 0.05 to 2.70 milliequivalents per gram, more preferably 0.25 to 1.62 milliequivalents per gram. The amine polymer component of the coating compositions of the present invention is provided in an aqueous medium in an amount of 20 to 65 weight percent resin solids, preferably 35 to 50 weight percent, and has a value of pH of 7.0 to 10, preferably 7.5 to 9.5. In principle, suitable amine comonomers are any of the polymerizable olefinically unsaturated compounds containing at least one primary or secondary amino group, for example: amine acrylates and amine methacrylates such as tert-butylaminoethyl methacrylate or meta-isopropenyl-a, a- dimethylbenzylamine. Amino groups can also be obtained by reaction of acid polymers with azidirines such as ethylene imine, or by reaction of blocked and epoxy ketimines, as well as by other known techniques for adding amine function to polymers. Hydroxyl monomers are not required in the present invention, but when used, they may be included in the monomer mixture in amounts such that the monomers having hydroxyl group are used in amounts of about 0 to 30 weight percent, preferably 0 to 10 weight percent based on the total weight of monomers used to copolymerize the amine polymer. Suitable monomers containing hydroxyl groups include, in particular, hydroxyalkyl 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-hydroxyethyl acrylate or methacrylate. or 3-hydroxypropyl, the hydroxybutyl acrylates or methacrylates isomers and mixtures of these monomers. The third group of olefinically unsaturated monomers that can be used for the production of the amino polymers are olefinically unsaturated compounds which contain neither amino groups 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 acrylates or methacrylates containing tertiary amine and the methacrylates corresponding to these acrylates. Also included are styrene, alkyl-substituted styrenes, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl stearate and mixtures of these monomers. The monomers of this third group are used in amounts of 50 to 90 weight percent, preferably of about 40 to 80 weight percent, based on the total weight of the monomers used. Aminic polymers are produced in water in the presence of an emulsifier. The details of this polymerization process are well known to those skilled in the art. A novel feature of polymerization is the selection of primers. The polymerization reaction is initiated with free radicals when the monomer mixture is added together with the initiator mixture over a period of about 1 to 10 hours, preferably about 3 to 6 hours, at the reaction temperature. After this, additional initiator may optionally be added to bring the polymerization to a conversion of at least 99 percent. Suitable emulsifiers for use in the polymerization include anionic, nonionic and amphoteric emulsifiers (if they are not non-ionic). Many such emulsifiers are commercially available, and several of them are described in the examples given herein. The selection of the initiator compound used in the polymerization is important in the present invention. To achieve the results of the present invention, azo initiators having carboxyl groups are used. An initiator of this type is 4,4'-azobis (4-cyanovaleric acid), which is commercially available as the V-501 initiator "from Wako Chemicals USA, Inc. The initiators are used in amounts of about 0.05. at 10 weight percent, based on the total amount of monomers In general, the polymerization reaction takes place at a temperature in the range indicated above, preferably at a temperature of about 50 to 100 ° C under atmospheric pressure. Exact polymerization is determined by the initiator used.The molecular weight of the polymers can be regulated with standard regulators such as n-dodecyl mercaptan, diisopropyl xanthogen disulfide, di- (methylenetrimethylolpropane) -xanthogen disulfide and thioglycol. in amounts of up to about 10 weight percent, based on the monomer mixture The polyisocyanate component (b) can be any polyisocyanate containing isocyanate groups bound aliphatic, cycloaliphatic, arylaliphatic and / or aromatically, which is liquid at room temperature. The polyisocyanate component is preferably unmodified to be dispersible or water soluble, although it may be modified in a less preferable embodiment. The polyisocyanate component (b) is preferably a polyisocyanate or mixture of polyisocyanates exclusively containing aliphatic and / or cycloaliphatically bound isocyanate groups and having an NCO functionality of about 2.0 to 5.0. If necessary, the polyisocyanates can be used in admixture with small amounts of inert solvents to reduce the viscosity. However, the maximum amount in which this solvent is used is sufficient for the coating compositions to contain a maximum of 20 weight percent solvent, based on the amount of water and any possible solvent still present in the dispersions of the solvent. polymer. Suitable solvents for the polyisocyanates include aromatic hydrocarbons such as petrol solvent, acetates, or the solvents designated as suitable for the polymerization of component (a).

Suitable polyisocyanates include those containing aromatic or (cyclo) aliphatically bound isocyanate groups, with (cyclo) aliphatic polyisocyanates being particularly preferred. Particularly suitable are polyisocyanates based on 1,6-hexamethylene diisocyanate, l-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethyl cyclohexane (IPDI) and / or bis- (isocyanato-cyclohexyl) -methane, in particular those based on 1,6-hexamethylene diisocyanate. Other suitable polyisocyanates based on these diisocyanates can include derivatives of biuret, urethane, uretdione and / or isocyanurate of these diisocyanates which, after their production, have been released in the known manner, preferably by distillation, from the excess starting diisocyanate to a residual content of less than 0.5 weight percent. The aliphatic polyisocyanates for use according to the invention include hexamethylene-based biuret polyisocyanates based on mixtures of N, N ', N "-tris- (6-isocyanatohexyl) biuret with small amounts of their higher homologs. can be obtained by the processes described in US Patent Nos. 3,124,605; 3,358,010; 3,903,126; 3,903,127 or 3,976,622. Cyclic trimers of 1,6-hexamethylene diisocyanate are also preferred which correspond to the criteria mentioned above. they can be obtained according to U.S. Patent No. 4,324,879 and which are based on N, N'N "-tris (6-isocyanatohexyl) -isocyanurate in admixture with small amounts of their higher homologs. The aromatic polyisocyanates which can also be used according to the invention, but which are less preferred, are based on 2, 4-diisocyanatotoluene or commercial mixtures thereof with 2,6-diisocyanatotoluene or based on 4,4'-diisocyanatodiphenylmethane or mixtures of them with their isomers and / or higher homologs. Aromatic polyisocyanates of this type include urethane isocyanates obtained by reaction of excess amounts of 2,4-diisocyanate toluene with polyhydric alcohols such as trimethylolpropane and subsequent distillation of excess unreacted diisocyanate. Other aromatic polyisocyanates include the trimers of the aforementioned monomeric diisocyanates which have also been released from the excess of monomeric diisocyanates, preferably by distillation, after their production. To prepare ready-to-use coating compositions, the polyisocyanate component (b) is emulsified in an aqueous dispersion of polymer component (a) containing amino group. The dissolved or dispersed polymer simultaneously serves as an emulsifier for the added polyisocyanate. Optionally, the dispersing component (b) can be aided by a separate surfactant compound. The mixing can be carried out by simple stirring at room temperature. The amount of the polyisocyanate component is selected to provide an NCO: NH equivalent ratio. { or NCO equivalent ratio: (NH + OH) if the hydroxyl function is present} , based on the isocyanate groups of component (b) and the primary or secondary amino groups and hydroxyl groups of component (a), of less than 1: 1, preferably of at least 0.5: 1. The ratio depends on the particular isocyanate used. For the purposes of the present invention, a primary amino group is considered as an equivalent of two, and a secondary amino group is considered to be equivalent to one. Thus, NH in the above relations represents equivalents of amine hydrogen. The additives typically used in coating technology can be incorporated into the coating composition of the present invention. The additives include foam inhibitors, leveling enhancers, pigments, dispersion aids for pigments, etc., and are preferably introduced initially into the component (a). The coating compositions according to the injection thus obtained are suitable for virtually any type of application where high performance is desired. They are useful, in particular, for coating metal surfaces and various plastic surfaces. The invention is further illustrated, without intending to limit it, with the examples given below 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 an aqueous acrylic polymer with secondary amine function through an emulsion polymerization technique. Ing redientes Parts by weight Initial charge Deionized water 600.0 ABEX EP-1201 64.2 Feeding 1 n-Butyl acrylate 300.8 Methyl methacrylate 179.2 Tert-butylaminoethyl methacrylate 160.0 Feeding 2 V- 5012 16, 0 Aqueous ammonia (29.7%) 7.0 Deionized water 296.6 1 Ammonium salt of sulphonated nonylphenoxypoly (ethyleneoxy) ethanol (30% active), from Rhone Poulenc, USA. 2, 4 '-Azobis (4-cyanovaleric acid), from Wako Chemicals USA, Inc. The initial charge was heated to a temperature of 80 ° C, with stirring, in a reaction vessel for an aqueous emulsion polymerization, 40 grams of Feed 1 was added to the reaction vessel and kept about 5 minutes to recover the temperature , followed by the addition of 40 grams of Feed 2 and maintenance of the reaction mixture at a temperature of 80 ° C for 30 minutes. The temperature was then raised to 85 ° C, and the reaction mixture was maintained for minutes at this temperature. The remaining Feeding 1 and Feeding 2 portions were added to the reaction mixture simultaneously over a period of 3 hours while maintaining the temperature of the reaction mixture at about 85 ° C. Upon completion of the additions, the reaction mixture was maintained for 2 hours at 85 ° C to complete the polymerization. The product was filtered to obtain a dispersion with a resin content of 40.6% determined at 110 ° C for 1 hour and a pH of 9.27.

EXAMPLE 2 Ref .: 95-187-032 The initial charge and feeds given below were used in the preparation of an acrylic aqueous polymer of secondary amine function by an emulsion polymerization technique.

Ingredients Parts by weight Initial charge Deionized water 300.0 ABEX EP-1201 19.2 Feeding 1 n-Butyl acrylate 96.0 Methyl methacrylate 160.2 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 stirring in a suitable reaction vessel for aqueous emulsion polymerization. 25 grams of Feed 1 was added to the reaction vessel and kept for 10 minutes to recover the temperature, followed by the addition of 25 grams of Feed 2 and holding the reaction mixture at a temperature of 85 ° C for 30 minutes . The remaining Feeding 1 and Feeding 2 portions were then added to the reaction mixture simultaneously over a period of 3 hours while maintaining the temperature of the reaction mixture at about 85 ° C. Upon completion of the additions, the reaction mixture was maintained for 2 hours at 85 ° C, to complete the polymerization. The product was filtered to obtain a dispersion with a resin content of 40.2% determined at 110 ° C for one hour and at a pH of 8.8.

EXAMPLE 3 (Comparative) A secondary amine functional polymer was prepared for comparison purposes in the same manner as that described 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 in an emulsion in 300 grams of deionized water was batch-polymerized. in the presence of 0.7 grams of ammonium persulfate and 0.7 grams of sodium metabisulfite as initiators, and in the presence of 20 grams of ABEX EP-120 (active 30 percent) 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 persulfate dissolved in 10 grams of deionized water and 0.7 grams of sodium metabisulfite dissolved in 10 grams of deionized water and raising the reaction temperature to 85 ° C. The reaction mixture was maintained about 1 hour at 85 ° C. The resulting dispersion was filled with granules, and after filtration a dispersion having 31.4 percent solids determined was obtained. 110 ° C for one hour. The product was unsuitable for use in a coating composition due to its granule content. The following Examples A, B and C are coating compositions formulated with the anionic amine polymers of Examples 1 and 2. The pH of each composition was greater than 7.0.

EXAMPLE A Ingredients Parts by weight Crushed pasta ~ Deionized water 8,330 TAMOL 8503 0,500 Surfactant PGNP-154 0,574 TRITON GR7MS 0,260 PLURONIC P-1036 0,056 DEE FO 97-37 0,121 BUSAN 11-M18 2,120 ZB-3259 3,571 NYAD 125010 1,228 TI-PURE R-902-3811 3,380 BAYFERROX 391012 0,444 Black BAYFERROX 318M13 0,712 MICROTALC MP-12-5014 8,288 BARIMITE XF15 3,287 ATTAGEL 5016 0,223 TEXANOL17 0,245 Deionized water 4,457 Thickener DSX-151418 0,243 Dilution n-Propanol19 0,122 Amino acrylate of Example 1 27,158 EXXATE 90O20 2,732 Isocyanate Isocyanate anionic21 3,346 EXXATE 900 0.549 Deionized water 28,054 EXAMPLE B Ingredients Parts by weight Tritur paste CtA Deionized water 13,456 TAMOL 850 0,527 Surfactant PGNP-15 0,502 Deionized water 4,77 TRITON GR7M 0,126 PLURONIC P-103 0,110 DEE FO 97-3 0, 140 MOLYWHITE 21222 2,324 ZB-325 1,163 SICORIN RZ23 0,079 MICROTALC MP-2 -50 13,764 BARIMITE XF 5,459 TI-PURE R902-38 2,389 BUFF Ti02 4 1,183 RAVEN 41025 O, 008 BAYFERROX 14OM26 0,008 BAYFERROX 3910 0,276 BLACK BAYFERROX 318 M 0.440 ATTAGEL 50 0,117 TEXANOL 0,279 Thickener DSX-1514 0,063 Dilution n-Propanol 0,031 Dichromate Sodium27 0.210 Amino Acrylate from Example 2 35,322 EXXATE 900 3,532 Deionized water 8,475 SANTICIZER 16028 1,048 EMULSIONANT Isocyanate29 0.766 Isophorone diisocyanate30 1.073 Deionized water 6,500 EXAMPLE C Ingredients Parts by weight Crushed paste Deionized water 7,021 TAMOL 850 0,527 Surface active agent PGNP-15 0,669 TRITÓN GR-7M 0.421 DEE FO 97-3 0,118 RAVEN 410 0.156 TI-PURE R902-38 1,872 BUFF TI02 7,489 MICROTALC MP-12-50 10,648 BARIMITE XF 4,212 SHIELDEX31 4,088 Deionized water 9.819 Sodium dichromate 0.234 Dilution Amine acrylate of Example 2 35.212 EXXATE 900 4,808 Deionized water 8,449 Isocyanate DESMODUR N 340032 3, 049 EMULSIONING33 0, 829 SILQUEST Y- 966934 0, 379 3 Tamol 850 - Aqueous pigment dispersant from Union Carbide Chemicals & Plástic Company, Industrial Chemicals Div., 39 Old Ridgeburg Rd., Danbury, Connecticut. 4 PGNP-15- Nonyl phenol polypropoxylated, nonionic surfactant produced by PPG Industries, Pittsburg, Pennsylvania.

Triton GR-7M - Anionic Surfactant, from Union Carbide Chemicals & Plastic Company, Industrial Chemicals Div., Danbury, Connecticut. 6 Pluronic P-103 - Nonionic Surfactant, from BASF Corporation, Chemical Div., Parsipanny, New Jersey. 7 DEE FOR 97-3 - Defoamer from Ultra Additives, Inc., Paterson, New Jersey. 8 BUSAN 11-Ml - Barium Metaborate, from Buckman Laboratories, Inc., Memphis, Tennesee. 9 ZB-325 - Zinc Borate from Polymer Additives Group, Southfield, Michigan. 10 NYAD 1250 - Wollastonita, Nyco Minerals Inc. Willsboro, New York. 11 TI-PURER R 902-38 - Pigment of titanium dioxide, from E. I. du Pont de Nemours & Co., Wilmington, Delaware. 12 BAYFERROX 3910 - Yellow iron oxide pigment, from Bayer Corporation, Pittsburg, Pennsylvania. 13 Black BAYFERROX 318M - Black iron oxide pigment, from Bayer Corporation, Pittsburg, Pennsylvania. 14 MICROTALCR MP-12-50 - Magnesium Silicate Hydrate, by Whittaker, Clark & Daniel Inc., South Plainfield, New Jersey.

BARIMITE XFR - Barium sulphate, from Cyprus Industrial Mineral Co. , Cartersville, Georgia. 16 ATTAGEL 50 - Atapulgita, from Engelhard Corporation, New Jersey. 1 TEXANOL - Solvent, from Eastman Chemical Products, Inc., Kingsport, Tennessee. 18 DSX-1514R - Thickener, from Henkel, Kankakee, Illinois. 19 n-Propanol - Solvent, from Eastman Chemical Products, Inc., Kingsport, Tennessee. 20 EXXATER 900 - C9 alkyl acetate solvent, from Exxon Chemical Co. , Houston Texas. 21 Anionic isocyanate obtained by the following reaction: In a 3-neck round bottom flask of 1 liter capacity, isophorone diisocyanate (318.2 grams, 2.88 NCO equivalents), DESMODUR W (188.6 grams) was introduced. , 1.44 equivalents of NCO) and propoxylated sodium 1,4-butanediol sulfonate (244.7 grams, 1.03 equivalents of OH). The flask was heated to 90 ° C and a layer of nitrogen was applied throughout the reaction. The flask was maintained at 90 ° C until the isocyanate equivalent weight reached 225. Sodium 1,4-butanediol sodium propoxylate was prepared according to British Patent No. 1,447,612 by hydro-sulfonation of the reaction product of 1,4-butenediol (1 mol) with propylene oxide (6 mol). 22 MOLYWHITE 212 - Protective corrosion pigment from Shervin Williams Chemicals, Coffeyville, Kansas. 23 SICORIN RZ - Protective corrosion pigment, from BASF Corp. Rensselaer, New York. 24 BUFF Ti02 - Cover Pigment, from Hitox Corporation of America, Corpus Christi, Texas. 25 RAVENR 410 - Carbon black pigment, from Cities Service Co., Columbian Div., Akron, Ohio. 26 BAYFERROX 140 M - Red iron oxide pigment, from Bayer Corporation, Pittsbyrg, Pennsylvania. Sodium Dichromate - Sudden Rust Inhibitor, from Fisher Scientific Co., Chemical Mfg. Div. Fair Lawn, New Jersey. 28 SANTICIZER 160 - Butyl benzyl phthalate, from Monsanto, St. Louis, Missouri. 29 Emulsifier - A nonionic surfactant containing 62.3% T-1890 (an IPDI isocyanurate from Huís America, Inc. Piscataway, NJ 08855), 28.8% CARBOWAX 750ME (a monofunctional polyether surfactant from Union Carbide Chemicals & Plástic Co., Inc., S. Charleston, WV 25303), 16.9% diethylamine (secondary amine from Union Carbide, S. Charleston, WV) prepared in methyl ethyl ketone and PROGLYDE DMM (solvent, dipropylene glycol dimethoxyether, from Dow Chemical USA, Chemicals and Performance Products Dept., 100 Larkin Ctr., Midland, MI 48674). Isophorone Diisocyanate - Monomeric Aliphatic Isocyanate, from Bayer Corporation, Pittsburgh, PA. 31 SHIELDEX - Corrosion Protective Pigment, by Grace, Davison Chemical Div., Baltimore, MD 21203. 32 DESMODURR N 3400 - A Trimer Isocyanate, from Bayer Corporation, Pittsburgh, Pennsylvania. 33 Emulsifier - 'A non-ionic surfactant containing 75% of T-1890 (an isocyanurate from IPDI, of Huís America, Piscataway, NJ 08855) and 25% of CARBOWAXR 750ME (a monofunctional polyether surfactant, from Union Carbide Chemicals &Plastics Co., Inc., Solvents Coating Materials Div., S. Charleston, WV 25303), prepared in methyl ethyl ketone and PROGLYDE DMM (dipropylene glycol dimethoxyether, Dow Chemical Co., Midland, MI). 34 SILQUESTR Y-9669 - Amino-silane from OSi Specialties, Inc., Sistersville, West Virginia. The coating compositions of Examples A to C were prepared as follows: In a grinding vessel, under high speed stirring with Cowles blade, the pigments were sieved by introducing them into the other components of the grinding paste (except the thickener ).

After stirring for 5 minutes, the Cowles blade was replaced by a moving wheel blade, and then zircon beads were added. This mixture was stirred at high speed for one hour, after which the beads were separated from the crushed paste. The thickener (DSX-1514) was then added to the ground paste and stirred at high speed for five minutes, after which the ground paste was diluted with the dilution ingredients, the isocyanate portions of the 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, then diluted to 35% solids with deionized water, and then stirred immediately with moderate agitation in the container containing the rest of the ingredients In Example B, 75% isophorone diisocyanate was mixed with 25% isocyanate emulsifier.This combination was stirred with moderate agitation in the container where the rest of the ingredients were. In Example C, the isocyanate emulsifier was mixed with SILQUEST Y-9669 to 1 part isocyanate per 1 part amine in equivalents, after 24 hours of induction, 25% of the mixture was mixed with isocyanate DESMODUR N 3400. This isocyanate combination was stirred with moderate agitation in the vessel containing the rest of the ingredients. Each of the coating formulations of Examples A, B and C was tested for performance by application on a substrate prepared as follows. The substrate for each Example consisted of 32-gauge cold-rolled steel, unpolished (from Advanced Coating Technologies, Inc., Hillsdale, Michigan, code: APR10288) sanded with P180 abrasive paper (P180-216U, Production RN FRE- CUT, weight of Paper A, open layer, manufactured by 3M, St Paul, MN). The substrate was washed with Acryli-Clean or DX-330 (from PPG Industries, Pittsburg, PA, as a wax and grease remover) and rubbed with a cloth without fiber particles (from Scott Paper Company, Philadelphia, Pennsylvania, as Scott Precision Wipes). After at least 24 hours of induction, each of the compositions of the examples was applied by compressed air spray at 0.003163 Kg / mm2 gauge (45 psig) on the previously prepared substrates. Each coated substrate was air dried at ambient conditions for 1 hour. Each was then dry-sanded using P400 abrasive paper (P400-213Q, Imperial Wetordry Production paper, weight "A", 3M, St. Paul, Minnesota) immediately and, when necessary, at successive 1-hour intervals. . The time elapsed until it was observed that the coating of the example could be subjected to sanding, that is, when the abrasive paper was not clogged, was taken as the minimum time required from the application until it could be sanded. Immediately after each spray application, the portion of each composition of the remaining example, approximately 85 to 100 grams, was stored in a hermetically sealed container of 0.268 liters (1/2 pint). The sample containers were stored at room temperature for two months, reopened and observed for fluidity at 1-month intervals. The evaluation of the adhesion of the coating of each example to the substrate was carried out by applying an adhesive tape (2 inches - 5 cm - of "232 Masking Tape", manufactured by 3M, St. Paul Minnesota), then one hour of time of curing and drying, and then the tape came off. Additional adhesion tests were carried out following the method ASTM D3359, Method B, in which the example coating was scratched with a Gardner Cros Cut Tester test device, Model PAT, provided with a PA-2056 blade, both manufactured by Gardco, Pompano Beach, Florida. The scratched coatings were tape tracked using Permacel 99 tape after the example coatings had been dried and cured for 96 hours, and again after an additional 96 hours during which they were exposed to a temperature of 37.7. ° C (100 ° F) and 100% humidity.

The results of these behavior tests are given in Table 1. TABLE 1 N.A., or "not applicable," indicates that no further testing was necessary. An assessment as "failure" under the heading SANDING indicates clogging of the abrasive paper due to the introduction of the coating between the particles of the paper. An assessment as "failure" under the heading ADHERENCE indicates less than 95% adhesion of the coating of the example on the substrate. An assessment as "failure" under the heading FLUID indicates an example coating with a viscosity that does not allow spraying, even when diluted with water. The following examples illustrate embodiments of the invention where the coating composition is supplied in the form of two separate packages for the amine polymer and the polyisocyanate. Examples 4 and 5 relate to amine polymers employed in the coating formulations of Examples D and E.

EXAMPLE 4 The following initial charge and feeds were used in the preparation of aqueous acrylic polymer of secondary amine function by the emulsion polymerization technique.

Ingredients Parts by weight Initial charge Deionized water 600.0 ETHOMEEN C / 25 * 19.2 Feeding 1 n-Butyl acrylate 300.8 Methyl methacrylate 179.2 Tert-butylaminoethyl methacrylate 160.0 Feeding 2 Initiator V-501 16 , 0 Aqueous ammonia (29.7%) 7.0 Deionised water 296, 6 * Polyoxyethylene (15) cocoamine, from Akzo Chemie America The initial charge was heated to a temperature of 80 ° C by stirring in a suitable reaction vessel for polymerization in aqueous emulsion. 40 grams of Feed 1 was added to the reaction vessel and kept for about 5 minutes to recover the temperature, followed by the addition of 40 grams of Feed 2 and maintaining the temperature of the reaction mixture at 80 ° C for 30 minutes. The temperature was then raised to 85 ° C, and the reaction mixture was held 30 minutes at this temperature. The remaining Feeding 1 and Feeding 2 portions were added to the reaction mixture simultaneously over a period of 3 hours while maintaining the temperature of the reaction mixture at about 85 ° C. Upon completion of the addition, the reaction mixture was maintained at 85 ° C for 2 hours to complete the polymerization. The product was filtered to obtain a dispersion with a resin content of 41.5 percent determined at 110 ° C for one hour and at a pH of 9.33.

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

Ingredients Parts by weight Initial charge Deionized water 300.0 ABEX EP-120 19.2 Feeding 1 n-Butyl acrylate 96.0 Methyl methacrylate 160.0 Tert-butylaminoethyl methacrylate 64.0 Feeding 2 Initiator 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 stirring in a suitable reaction vessel for aqueous emulsion polymerization. 25 grams of Feeding 1 was added to the reaction vessel and held for approximately 10 minutes to recover the temperature followed by the addition of 25 grams of Feeding 2 and maintaining the temperature of the reaction mixture at 85 ° C for 30 minutes. The remaining Feeding 1 and Feeding 2 portions were then added to the reaction mixture simultaneously over a period of 3 hours while maintaining the temperature of the reaction mixture at about 85 ° C. Upon completion of the addition, maintained the reaction mixture for 2 hours at 85 ° C to complete the polymerization. The product was filtered to obtain a dispersion with a resin content of 40.2 percent determined at 110 ° C for one hour and at a pH of 8, 8.

EXAMPLE D Ingredients Parts by weight Env ase 1 Deionized water 13,048 TAMOL 850 0.605 Surface active agent PGNP-15 0.166 SOLSPERSE 2700035 0.451 TRITON GR-7M 0.309 DEE FO 97-3 0.077 NALZIN 236 7,064 NYAD 1250 3,531 MICROTALC MP-12-50 10,008 BARIMITE XF 3,959 TI-PURE R902-38 4,179 BAYFERROX 3910 0,550 BLACK BAYFERROX 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 EMULSIONANT37 1,105 DESMODUR N 3400 3,315 EXAMPLE E Ingredients Parts by weight Package 1 Deionized water 6,003 TAMOL 850 0,450 Surfactant PGNP-15 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 Ti02 6,403 RAVEN 410 0,133 Strontium Chromate 38 0,300 Deionized Water 8,028 Thickener DSX-1514 0,200 n-Propanol 0,100 Amino Acrylate from Example 5 30,105 EXXATE 900 5,002 Deionized Water 21,094 Package 2 Emulsifier 37 0,870 DESMODUR N 3400 2,611 SOLSPERSER 27000 - Hyperdispersant from ICI Surfactants, Wilmington, Delaware. 36 NALZINR 2 - Anti-corrosive pigment from Rheox, Inc. PO Box 700, Hightstown, NJ. 37 Emulsifier - A nonionic surfactant containing 33.3% of T-1890 (an isocyanurate from IPDI, of Huís America, Piscataway, NJ 08855), 11.1% of CARBOWAXR 750ME, 55.6% of Solvactant® DMH- 7 (a monofunctional polyether surfactant and a nonionic surfactant, respectively, both from Union Carbide Chemicals and Plastics Co., Inc., Danbury, Connecticut) 38 Strontium chromate - Pigment Pigments corrosion inhibitor pigment. Coating compositions of Examples A and B were prepared as compositions in two packages with the amine acrylate, pigments and additives in one of the containers (Pack 1) and the isocyanate and isocyanate emulsifier in a second pack (Pack 2). a suitable grinding vessel and under high speed agitation with a cowles blade, the container 1 was prepared by mixing the pigments in a mixture of surfactant, defoaming agent and water. He replaced Cowles with a mobile wheel pallet and zircon pearls were added. This mixture was stirred at high speed for 1 hour, after which the beads were separated from the grinding paste. The thickener (DSX-1514) was added to the ground paste and stirred at high speed for 5 minutes. An appropriate amount of this ground paste was then added to the amine acrylate and water. Each of the formulations of Examples D and E were tested for their performance on the application on a substrate prepared in the same manner as that described above in connection with Examples A, B and C. Prior to spray application , Pack 2 was added to Pack 1 for each example, with moderate and constant agitation. Each of the compositions of the examples was applied by spraying with compressed air at 0.003163 kg / mm2 gauge (45 psig) on the previously prepared substrates. The coated substrates were air dried at ambient conditions for 1 hour. Each of them was sanded using P400 abrasive paper (P400-213Q, Imperial Wetordry production paper, "A" weight, manufactured by 3M, St Paul, Minnesota) immediately and, when necessary, at successive one-hour intervals. The time that elapsed until the coating of the example showed being able to sand, that is, when the abrasive paper was not clogged, was taken as the minimum time required from the application until it could be sanded.

Each of the two component coating compositions was additionally subjected to a potential gas formation test. Immediately after each spray application, the portion of each remaining mixed composition, approximately 85 to 100 grams, was introduced into a 0.28 liter (1/2 pint) container that was sealed. The sample containers were opened at 1-hour intervals and evaluated for the formation of a gas pressure by observing an audible sizzle of the pressurized gas, audible tapping of the lid or observation of bubbling or foaming of the wet sample. The evaluation of the adhesion of each coating to the substrate was carried out 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 given in Table 2 TABLE 2 N.A. , or "not applicable" indicates that no further trials were needed. An assessment as "failure" under the heading SANDING indicates clogging of the abrasive paper due to the introduction of the coating on the granules of the abrasive paper. An assessment as "failure" under the heading of ADHERENCE indicates a adhesion of less than 95% of the coating of the example on the substrate. An assessment as "failure" under the heading of GAS FORMATION indicates bubbling of the wet sample due to gas evolution. Although the invention has been described in detail for illustrative purposes of the best mode of the invention, it is to be understood that this detail is solely for this purpose and that those skilled in the art can make variations without departing from the spirit and scope of the invention such as it is defined in the claims.

Claims (7)

1. CLAIMS 1. An aqueous coating composition having a pH above 7.0 which has a binder comprising polyureas formed by the combination of: (a) an anionic amine polymer synthesized in water from olefinically unsaturated compounds containing groups isocyanate reagents selected from the group consisting of primary amino groups, secondary amino groups, or combinations thereof, said olefinically unsaturated compounds being substantially free of acid groups, said polymerization being carried out in the presence of an azo initiator dispersed in water by neutralization of acid groups present in the initiator; and (b) a polyisocyanate.
2. 2. The coating composition according to claim 1 wherein the polyisocyanate is in combination with a nonionic surfactant.
3. 3. The coating composition according to claim 1 wherein the polyisocyanate and the amine polymer are provided in an NCO / NH equivalent ratio to each other from 0.5: 1 to 5: 1.
4. 4. The coating composition according to claim 1 wherein the ratio of NCO / NH equivalents is less than 1: 1.
5. 5. The coating composition according to claim 1 wherein components (a) and (b) are supplied in separate packages.
6. 6. The coating composition according to claim 1 wherein the components (a) and (b) are supplied mixed in a single container.
7. 7. The coating composition according to claim 6 wherein said polyisocyanate has an average functionality of not more than two isocyanate groups per molecule.