MXPA00008023A - Waterborne, ambient temperature curable film-forming compositions - Google Patents

Abstract

A homogeneous oil-in-water emulsion suitable for use as a curable film-forming composition is provided. The emulsion is a mixture of hydrophobic polyisocyanate cross-linking agent containing at least one tertiary isocyanate group and a surface active isocyanate reactive material. The surface active isocyanate reactive material comprises an active hydrogen-containing acrylic copolymer containing aromatic groups and having a glass transition temperature of at least about 0°C. A multi-component composite coating composition is also provided by the present invention. The compositions are curable at ambient temperatures and are suitable for use in automotive applications.

Description

COMPOSITIONS FOR I CUL GES CURABLE TO TEMPERATURE AMBIENTE, IN SUSPENSION IN WATER BACKGROUND OF THE INVENTION [0001] The present invention relates to waterborne pelvic-liquid compositions which are curable at ambient or higher temperatures, including polyisocyanate re-entrapping agents and acrylic copolymers containing active hydrogen having high transition temperatures vl-trea . U.S. Patent No. 5,466,745 issued to Fiori et al. Describes functional polyisocyanate crosslinking agents that can be emulsified in water with a surfactant reactive isocyanate material and use the emulsion to form a curable film composition. The emulsified materials are in the form of an oil-in-water emulsion which exhibits good stability and yet the polyisocyanate and the isocyanate reactive material are highly reactive when applied as a film. The patent recommends that these isocyanate reactive materials have a glass transition temperature (Tg) of less than about 0 ° C. It is considered that the low Tg materials are more mobile during the curing reaction giving the reactive isocyanate group, i.e., hydroxyl, more opportunity to locate an isocyanate group thereby facilitating the crosslinking reaction. The high Tg reactive isocyanate materials, on the other hand, are relatively immobile resulting in less opportunity to localize and react with the polyisocyanate. A drawback of using low Tg reagent isocyanate materials, however, is that the resulting cured films are inherently softer and less resistant to solvents than what is recommended for self-anointing applications. It would be desirable to provide an aqueous-based film-forming composition containing a polyisocyanate curing agent and a reactive isocyanate material which can be stably dispersed in water, reactive when applied as a film, and formed into a hard, solvent-resistant film.

COMPENDIUM OF THE INVENTION According to the present invention, an oil in water emulsion is provided which includes an aqueous medium in which an organic phase has been emulsified including a mixture of: (1) a polyisocyanate crosslinking agent containing an aromatic group which it is not water dispersible and contains at least two isocyanate reactive groups, of which at least one is a tertiary isocyanate group; and (2) a reactive surfactant isocyanate material. The surfactant reactive isocyanate material includes an acrylic copolymer containing active hydrogen having a glass transition temperature of at least about 0 ° C, prepared from a mixture of polymerizable ethylenically unsaturated monomers including from about 5 to about 80, preferably from about 10 to about 40 weight percent, based on the total weight of monomer solids used to prepare the copolymer, of an ethylenically unsaturated aromatic monomer. The emulsion is suitable for use as a petroleum composition (coating) and can be cured at ambient or elevated temperatures. The emulsions are stable and have unexpectedly good reactivity when applied as a re-coating. Although not intended to be bound by any theory, the use of an ethylenically unsaturated aromatic monomer that provides the highest Tg is considered to make the higher Tg acrylic polymer more compatible with the polyisocyanate containing an aromatic group, allowing the Reactive isocyanate groups are better aligned with the isocyanate groups, thereby facilitating the cure. The present invention also provides a multi-component composite coating composition. The coating composition includes a base coat deposited from a pigmented film composition and a clear topcoat applied over the base coat in which the clear coat, or clear coat, is deposited from the oil in water emulsion. previously described.

DETAILED DESCRIPTION Polyisocyanate crosslinking agents suitable for use in the emulsifiable composition of the present invention include any liquid or solid polyisocyanate containing an aromatic group containing at least two reactive (unblocked) isocyanate groups, of which at least one is a tertiary isocyanate group. By "aromatic" is meant aryl-bellyl and araliphatic isocyanates. Such polyisocyanate crosslinking agents should be in and by themselves substantially hydrophobic and non-dispersible in water. Mixtures of polyisocyanates are also suitable. When mixtures of polyisocyanates are used, at least one of the polyisocyanates contains a tertiary polyisocyanate group and an aromatic group. Examples of polyisocyanates include, but are not limited to, meta-a, a, a ', a'-tetramethyllylynediisocyanate, para-a, a, a', a'-tetramethyl-xylylenediisocyanate, as well as biurets and isocyanurates of diisocyanates, wherein at least one of the diisocyanates used to prepare the biuret or isocyanurate contains a tertiary isocyanate group. A preferred polyisocyanate includes a urethane adduct of a polyol with a diisocyanate containing at least one tertiary isocyanate group. Suitable polyols include, for example, ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, and the like. Also suitable are oligomeric and polymeric polyols. The surfactant reactive isocyanate material contains both (i) functionality capable of reacting with isocyanate groups, and (ii) hydrophilizing functionality capable of rendering the reactive surfactant isocyanate material water dispersible. The preferred surfactant reactive isocyanate material is an acrylic copolymer, the hydrophilizing groups and the reactive isocyanate functionality being incorporated into the polymer by selection of the appropriate monomer or following modification. Examples which may be mentioned are ethylenically unsaturated carboxy-functional monomers and ethylenically unsaturated hydroxy-functional monomers. Reactive isocyanate functionality, in the sense in which it is used herein, refers to functionality that is reactive with isocyanate groups under the cure conditions of the curable emulsions. Such reactive isocyanate functionality is generally known to those skilled in the coatings art and includes, very commonly, active hydrogen functionality such as hydroxyl and amino groups. The hydroxyl is typically used as the reactive isocyanate functionality in coatings and is preferred for use in the present invention. The hydrophilizing functionality is also generally known to those skilled in the art of coatings and includes, very commonly, anion generating, cation generating and nonionic hydrophilic functionality. By anion generator and cation generator is meant functionality such as carboxyl (anion generator) or amino (cation generator) which, when properly neutralized, is hydrophilic in nature. Non-ionic hydrophilic functionality is, in and of itself, hydrophilic in nature. The amount of hydrophilizing functionality present in the reactive isocyanate material, at least after partial neutralization of the anion-generating groups or cation generators (if present), should be sufficient to render the reactive isocyanate material water-dispersible. The acrylic copolymers containing active hydrogen have a glass transition temperature (Tg) greater than about 0 ° C. Tg is described in PRINCIPLES OF POLYMER CHEMISTRY, Flory, Cornell University Press, Ithaca, NY, 1953, pages 52-57. The Tg can be calculated as described by Fox in Bull. Amer. Physic. Society, 1, 3, page 123 (1956). The Tg can be measured experimentally using a penetrometer such as a Du Pont 940 Thermomedian Analyzer. The Tg of the polymers in the sense in which it is used in the pre-senté memory refers to the calculated values unless otherwise indicated. Suitable acrylic copolymers are copolymers of one or more polymerizable acrylic monomers such as acrylic functional acid monomers, amine functional acrylic monomers, hydroxyl functional acrylic monomers, and other polymerizable unsaturated monomers such as vinyl monomers. The copolymers can be prepared in organic solvent using conventional free radical polymerization techniques. The polymer should contain from about 5 to about 80, preferably from about 10 to about 40, weight percent, based on the total weight of monomer solids used to prepare the acrylic copolymer, of an ethylenically unsaturated polymerizable aromatic monomer; from about 5 to about 80, preferably from about 10 to 40 percent by weight, based on the total weight of monomer solids used to prepare the polymer, of an ethylenically unsaturated hydroxyl functional acrylic monomer; and from about 20 to about 95, preferably from about 30 to about 70 weight percent, based on the total weight of monomer solids used to prepare the acrylic copolymer, of at least one different ethylenically unsaturated monomer.

The ethylenically unsaturated aromatic monomer can be selected from monomers such as styrene and alpha-methyl styrene, which includes substituted styrene or substituted alpha-methyl styrene where the substitution is in the para position and is a linear or branched alkyl group having about 1 to about 20 carbon atoms, for example, vinyl toluene, 4-vinyl anesol, and 4-vinylbenzoic acid. Also the ethylenically unsaturated aromatic monomer may contain molten aryl rings. Examples include 9-vinylanthracene and 9-vinylcarbazole. It is also possible to use mixtures of monomers. By "monomer" is meant true monomer; that is, it is not intended to include dimers, such as dimeric alpha-methyl styrene, trimers, or oligomers.

The ethylenically unsaturated hydroxyl functional monomer can be selected from, inter alia, acrylate • hydroxyethyl, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and mixtures thereof, with preference being given to "hydroxyethyl methacrylate." The additional ethylenically unsaturated monomers used to prepare the acrylic copolymer include acrylic monomers containing an acid group such as acrylic acid and methacrylic acid, amine groups containing monomers such as dimethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate, and meta-isopropenyl-, a-dimethylbenzylamine; alkyl esters of acrylic acid or methacrylic acid such as having 1-10 carbon atoms in the alkyl group such as methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate and cyclohexyl methacrylate and other polymerizable ethylenically unsaturated monomers such as nitriles such as acrylonitrile and methacrylonitrile; halides of vinyl and vinylidene such as vinyl chloride and fluoride-of vinylidene and vinyl esters such as vinyl acetate. Preferred are the functional acid and amine monomers such as acrylic and methacrylic acid and dimethylaminoethyl methacrylate, tert-butylaminoethyl methacrylate; and meta-isopropenyl-a, a-dimethylbenzylamine, because, after neutralization of the acid or amine group, the copolymer becomes hydrophilic. The acidic or functional amine monomer is used in amounts of up to about 25% by weight, preferably from about 1.0 to about 10.0%, based on the total weight of monomer solids used to prepare the acrylic polymer. The alkyl esters of acrylic and methacrylic acid are used in amounts of up to about 89%, preferably from about 30 to about 80% by weight, based on the total weight of monomer solids used to prepare the acrylic copolymer. The other ethylenically unsaturated copolymerizable, when used, are used in amounts of up to about 80%, preferably from about 10 to about 40%, by weight based on the total weight of monomer solids used to prepare the acrylic copolymer. The acrylic copolymer typically has a number average molecular weight (M of from about 700 to about 50,000, preferably from about 1000 to about 12,000 determined by gel permeation chromatography using a polystyrene standard, an acid number, in the case of anion generating groups, from about 15 to about 150 mg KOH / g resin, preferably from about 20 to about 70 mg KOH / g resin, more preferably from about 20 to about 35 mg KOH / g resin; of active hydrogen groups from about 2.5% to about 6% by weight, preferably from about 3% to about 5% by weight, more preferably from about 3.5% to about 4.5% by weight, based on 100% solids When formulating coating compositions from the emulsifiable compositions of the present invention, preferably the polyisocyanate crosslinking agent and the surfactant reactive isocyanate material include the primary film-forming components of the coating. The components are preferably present in amounts such that the ratio of NCO: active hydrogen group is of the order of from about 0.5: 1 to about 2: 1, preferably from about 0.8: 1 to about 1.2: 1. . The emulsifiable compositions of the present invention, in particular when used as coating compositions, may also include additional ingredients such as, for example, neutralizing agents to render the surfactant reagent isocyanate material, curing catalysts, and amounts relatively dispersible in water. less than organic solvent. When an acidic group is present in the reactive isocyanate material, any base can be used as the neutralizing agent to produce an anionic surfactant material. A base capable of converting a carboxyl group to a carboxylate ion is normally used as the neutralizing agent, including organic and inorganic bases such as sodium hydroxide and potassium sodium and potassium carbonate, and amines such as ammonia, primary, secondary and secondary amines. tertiary Likewise, when an amine group is present in the acrylic copolymer, any acid can be used as the neutralizing agent to produce a cationic surfactant material. When used, the neutralizing agents may be present in the organic phase to be emulsified, the aqueous medium to which the organic phase is emulsified, or both. The total amount of neutralizing agent should be sufficient to emulsify the polyisocyanate, the acrylic copolymer and other optional ingredients and the aqueous phase as an oil-in-water emulsion. In addition to the polyisocyanate, the acrylic copolymer and water, the composition may contain optional ingredients, in particular curing catalyst and organic solvents.

The curing catalysts for isocyanates are known to those skilled in the art. Preferred are organometallic catalysts and, in particular, organotin compounds such as dibutyltin diacetate, dibutyltin dioxide, dibutyltin dilaurate and the like. The organic solvents are in general those present in the various components. For example, many coating components are not commercially available on the basis of 100% solids, but rather have a somewhat lower solids content in an appropriate solvent. Preferably, no other organic solvent is added to or added to the emulsifiable compositions (or emulsion) to achieve acceptable results. Other optional ingredients such as, for example, plasticizers, surfactants, thixotropic agents, anti-gassing agents, organic cosolvents, flow controllers, antioxidants, UV light absorbers and similar additives conventional in the art may be included in the composition. The oil-in-water emulsions of the present invention are produced by the steps of: (a) mixing the components that form the organic phase of the emulsion; the organic phase can be defined as more than 50% organic by weight; and then (b) bringing the mixture into contact with an aqueous medium in proportions and under conditions to obtain an oil-in-water emulsion. The emulsions can be prepared by various known techniques, but are preferably prepared by adding the aqueous medium, continuously or in portions, to the organic phase under mixing conditions until phase inversion occurs. The additional aqueous medium can then be added to adjust the emulsion to the desired solids content and viscosity. The aqueous medium can only include water, or it can include other components such as the neutralizing agent, as indicated above. The aqueous medium may additionally include one or more other auxiliaries and additives common in the art, as well as minor amounts of water miscible organic solvent to facilitate emulsification or to regulate viscosity. Preferably such additional ingredients will be added to the organic phase and the aqueous medium will include only water or water plus a neutralizing agent. The oil-in-water compositions prepared by the above process can be used as curable curable compositions (coatings). The film-forming compositions of the present invention can be cured at room temperature; that is, 20 to 25 ° C, or heating to approximately 93 ° C (200 ° F) as desired to effect curing. The film-forming composition of the present invention is normally used as a clear coating applied only to a substrate or on top of a colored base coat as part of a multi-component coating composition. Suitable base coatings include those known to those skilled in the art. Curable base coatings are preferred at ambient temperatures. Alternatively, the composition of the present invention may contain color pigments conventionally used in surface coatings and may be used as a basecoat or high gloss monocoat; that is, a pigmented coating of high gloss. By "high gloss" it is meant that the cured coating has a gloss at 20 ° and / or a DOI ("image sharpness") measurement of at least about 80 measured by standard techniques known to those skilled in the art. Such standard techniques include ASTM D523 for brightness measurement and ASTM E430 for DOI measurement. Color pigments conventionally used in surface coatings are suitable and include, for example, inorganic pigments such as titanium dioxide, iron oxides, chromium oxide, chromate. lead, and carbon black, and organic pigments such as phthalocyanine blue and phthalocyanine green. It is also possible to use mixtures of the aforementioned pigments. Suitable metallic pigments include in particular aluminum foil, copper bronze lamella and mica covered with metallic oxide, nickel flakes, tin flakes, and their mixtures. When present, the pigment is incorporated into the coating composition in amounts of about 1 to about 80 weight percent based on the total weight of coating solids. The metallic pigment is used in amounts of about 0.5 to about 25 percent by weight based on the total weight of coating solids. Film-forming compositions can be applied to various substrates to which they adhere including wood, metals, glass, and plastic. The compositions can be applied with conventional means including brush application, dipping, flow coating, spraying and the like, but are most frequently applied by spraying. The usual spray techniques and equipment for air spraying and electrostatic spraying and manual or automatic methods can be used. During the application of a basecoating composition to the substrate, a film of the basecoat is formed on the substrate. Typically, the thickness of the base coat will be from about 0.01 to about 5 mils (from about 0.254 to about 127 microns), preferably from about 0.1 to about 2 mils (from about 2.54 to about 50). , 8 microns) thick. After application of the basecoat to the substrate, a film is formed on the surface of the substrate by expelling the solvent, ie organic solvent and / or water, from the basecoat film during an air drying period, sufficient to guarantee that the clear coating can be applied to the basecoat without dissolving the basecoating composition. Suitable drying conditions will depend on the particular composition of the basecoat, and on the ambient humidity with some compositions in suspension in water, but in general a drying time of about 5 to 60 minutes will be adequate to ensure that the mixture is minimized. the two coatings. At the same time, the basecoat film is suitably wetted by the clear coating composition so that satisfactory adhesion between coatings is obtained. In addition, more than one base coat and multiple clear coatings can be applied to develop the optimum appearance. The coating applied above is generally applied between coatingsp. ; that is, it is exposed to ambient conditions for approximately 1 to 20 minutes. The clear top coat composition can be applied to the base coated substrate by any conventional coating technique such as brush application, spraying, dipping or flow, but spray applications are preferred because of excellent gloss. Any of the known spray techniques such as compressed air spraying, electrostatic spraying and manual or automatic methods can be employed. After application of the clear coating composition to the base coat, the coated substrate can be cured at room temperature. The coated substrate can also be heated as desired, often up to about 93 ° C (200 ° F). In the curing operation, the solvents are expelled and the film-coating materials of the clear coating and the base coat are crosslinked. The curing operation is usually carried out at a temperature of the order of from 20 to 25 ° C, or up to about 93 ° C. The thickness of the clear coating is generally from about 0.5 to about 5 mils (from about 12.7 to about 127 microns), preferably from about 1.2 to about 3 mils (about 30.5). at about 76.2 microns). The invention will be better described by reference to the following examples. EXAMPLES A to I Examples A to I illustrate the preparation of acrylic copolymers. Examples A to C and F are illustrative of copolymers used in the present invention, demonstrating the preparation of acrylic copolymers containing a variety of ethylenically unsaturated aromatic monomers at various levels. Examples D, E and G to I are comparative because they demonstrate the preparation of acrylic copolymers containing monomers or dimers having high T s, but not ethylenically unsaturated aromatic monomers. EXAMPLE A An acrylic copolymer (Tg = 25 ° C) containing 35 wt.% Styrene was prepared as follows: DOWANOL PM acetate was charged (276.60 parts, dipropylene glycol monomethyl ether acetate, obtainable from Dow Chemical Co. .) in a four-neck flask which was equipped with a thermocouple, a reflux condenser with a nitrogen inlet adapter and a stirrer, and heated to re-flow under a nitrogen gas cushion. The initiator di-tert-amyl peroxide (67.08 parts) and 103.62 parts of BUTYL CELLOSOLVE acetate (2-butoxyethyl acetic acid ester, which can be obtained from Union Carbide Chemicals and Plastics Co., was mixed (initiator mixture). ., Inc.). A total of 391.25 parts of styrene, 324.18 parts of butyl acrylate, 335.36 parts of hydroxyethyl methacrylate, and 67.07 parts of acrylic acid were also mixed (feed A). The initiator mixture was added dropwise to the reaction vessel over a period of about 3.5 hours while maintaining the reaction at reflux. Ten minutes after the start of the addition of initiator, feed A was added dropwise to the reaction vessel over a period of 3 hours. Upon completion of the addition of feed A, a rinse of 22.88 parts of DOWANOL PM acetate was added. Upon completion of the addition of initiator, a rinse of 11.9 parts of DOWANOL PM acetate was added, and the reaction mixture was refluxed for 1 hour. After the completion of the retention time, the reaction mixture was cooled. The final product had a solids content of about 73 percent, a measured acid value of 34.6, a hydroxyl group content of 2.9% and an average molecular weight number of about 4458 determined by gel permeation chromatography using a polystyrene standard. Example B An acrylic copolymer (= 2 ° C) containing 19% by weight of styrene, 45% by weight of butyl acrylate was prepared, % hydroxyethyl methacrylate, and 6% acrylic acid as in Example A. The final product had a solids content of about 73 percent, a measured acid value of 34.7, a hydroxyl group content of 2, 9% and a number average molecular weight of about 3845 determined by gel permeation chromatography using a polystyrene standard.

Example C An acrylic copolymer (Tg = 5 ° C) containing 19% by weight of styrene was prepared as follows: A mixture of DOWANOL PM acetate (259.3 parts) and BUTYL CELLOSOLVE acetate (259.3 parts) was charged in a suitable reactor, and heated to reflux under a nitrogen gas pad. The initiator di-tert-amyl peroxide (125.8 parts) and 194.3 parts of BUTYL CELLOSOLVE acetate were mixed (initiator mixture). A total of 398.2 parts of styrene, 869.8 parts of butyl acrylate, 733.5 parts of hydroxyethyl methacrylate, and 94.3 parts of acrylic acid were also mixed (feed A). The initiator mixture was added dropwise to the reaction vessel over a period of about 3.5 hours while maintaining the reaction at reflux, and feed A was added dropwise to the reaction vessel over a period of 3 hours . The pressure in the reaction vessel was allowed to rise to 32 pounds per square inch. At the completion of feed addition A, a rinse of 42.9 parts of DOWANOL PM acetate was added. At the completion of the addition of initiator, a rinse of 22.3 parts of DOWANOL PM acetate was added, and the reaction mixture was kept under reflux pressure for 1 hour.

After the completion of the retention time, the reaction mixture was cooled and the pressure was released. The final product had a solids content of about 69.9 percent, a measured acid value of 26.5, a content of the hydroxyl group of 3.2% and an average molecular weight number of about 2736 determined by permeation chromatography. of gel using a polystyrene standard. Examples D to I The copolymers of Examples D to I were prepared using the procedure of Example C, except that the styrene was replaced as shown in the following table: Examples 1 to 10 Examples 1 to 10 illustrate the preparation of oil-in-water emulsions used to prepare curable film compositions. Examples 1 to 4 and 7 are illustrative of compositions of the present invention, demonstrating the preparation of compositions containing a variety of aromatic acrylic functional copolymers at various levels. Examples 5, 6, and 8 to 10 are comparative because they demonstrate the preparation of compositions containing acrylic copolymers having high Tgs, but which are not functional aromatics, or, as in example 5, contain an acrylic copolymer prepared from of a dimer. The ingredients were mixed in the order indicated. All compositions were prepared by premixing the acrylic copolymer (s) with the neutralizing amine, surfactant, additives, catalyst, and solvent to form a stable "component 1". The polyisocyanates, which when mixed together would form a stable "component 2", were then mixed well with component 1. The deionized water (component 3) was then added and mixed, preferably manually, until phase inversion occurred. form an oil-in-water emulsion. Sufficient deionized water was added to obtain a spray composition.

Ultraviolet light stabilizer obtainable from Ciba-Geigy Corp. Spherically locked amino ether light stabilizer obtainable from Ciba Geigy Corporation. Nonionic Fluorosurfactant obtainable from 3M Corporation Trimethylolpropane adduct with meta-a, a, a ', a'-tetramethylxylylene diisocyanate, 74% solids in butyl acetate, 10.2 weight percent free isocyanate, which can be Get from CYTEC Industries, Stamford, CT. Hexamethylene diisocyanate trimer, which can be obtained from Rhone Poulenc Cranbury, NJ.

* Comparative Example 1 Surfactant obtainable from BYK Chemie, Wallingford, CT.

Two sets of test panels were prepared as follows: twenty steel panels (two for each example) measuring 10.16 cm x 30.48 cm (4 x 12 inches) that had previously been coated with a layer of electrode primer. deposited and a primer that can be obtained from PPG Industries, Inc., such as ED5000 and GPX05379, respectively, were sandblasted with wet sand with # 600 grain paper, washed with solvent and then treated with an epoxy primer sealer /amine. A black base coat suspended in water was also applied to a set of panels, which can be obtained from PPG Industries, Inc., as ENVIROBASE®. The drying times before the application of the compositions of the examples were variable and were at room temperature or at temperatures not higher than 65.6 ° C (150 ° F). The compositions of the examples were applied by spraying using conventional spray equipment, applying approximately 38.1-76.2 microns (1.5-3.0 thousandths of an inch) in two coatings with a superposed layer at room temperature at 10 minutes. approximate between coatings. In the first set of panels (without basecoat), the compositions of the examples were sprayed as clear re-coatings directly onto the primed panels for the purpose of determining the Tukon hardness of the cured film without the softer basecoat influencing the the hardness (eliminating a source of variability). All panels were allowed to cure in environmental conditions for a minimum of 24 hours (+/- 4 hours) before doing a gasoline impregnation test. All other tests were performed after leaving the powdered panels cured at ambient conditions for 7 days. Some tests were done with the color-plus-clear composite panels and some were made with the clear coating directly on the primed panels as indicated. The results are indicated in the following table. * 1 Tukon hardness is the Knoop hardness value measured using a Tukon Microhardness Tester model 300 from Wilson Instruments according to ASTM D1474-92. Higher numbers indicate greater hardness. The tests were performed on panels in which the clear coating was applied directly to the primed substrate. The tests were made after 7 days of curing at room temperature. 2 The solvent resistance of methylethyl ketone was verified according to ASTM D5402. The tests were performed on panels in which the clear coating was applied directly to the primed substrate. The tests were made after 7 days of curing at room temperature. * 3 The percentage of film retention was determined by measuring the thickness of the film before and after the MEK solvent rubs. The tests were performed on panels in which the clear coating was applied directly to the primed substrate. The tests were made after 7 days of curing at room temperature. The gasoline impregnation test was performed on panels that were coated with a base coat and a clear coat, after 24 hours of curing at room temperature to determine the film's resistance to gasoline. A strip of 2.54 cm x 10.16 cm (1 x 4 inches) of the panel is partially immersed in 93 octane gasoline for three minutes, removed and the gasoline allowed to evaporate for 1 1/2 minutes. With cheesecloth wrapped tightly around the index finger and applying light uniform pressure, three double rubs are made. Any alteration of the color, tarnishing or softening of the film constitutes a level of failure. The softness of the film and loss of brightness is classified separately, but recorded as a single result. The softness of the film is classified using the numerical scale of 5 to 1, where 5 does not indicate change and 1 indicates failure of the film. The loss of brightness is classified on a scale from A to C, where A does not indicate loss of brightness and C indicates substantial loss of brightness. The data in the table indicates that the compositions prepared according to the present invention (examples 1-4 and 7) show excellent cure response as evidenced by the hardness of the film and the resistance to solvent and gasoline. The compositions prepared with copolymcontaining high Tg monomother than the aromatic monomcomprised by the invention (examples 5, 6, and 8-10) do not cure as well.

Claims (21)

Claims

1. An oil in water emulsion including an aqueous medium in which an organic composition has been emulsified including a mixture of: (1) a hydrophobic aromatic group containing polyisocyanate crosslinking agent containing at least two isocyanate reactive groups, of which at minus one is a tertiary isocyanate group; and (2) a surfactant reactive isocyanate material; including an acrylic copolymer containing active hydrogen having a glass transition temperature of at least 0 ° C, and prepared from a mixture of polymerizable ethylenically unsaturated monomers containing from 5 to 80 weight percent, based on the total weight of monomer solids used to prepare the copolymer, of an ethylenically unsaturated aromatic monomer, wherein said emulsion can be cured at ambient temperatures.

2. The oil in water emulsion of claim 1, wherein the mixture of ethylenically unsaturated monomers contains from 5 to 80 weight percent, based on the total weight of monomer solids of an ethylenically unsaturated hydroxyl functional monomer.

3. The oil-in-water emulsion of claim 1, wherein the ethylenically unsaturated aromatic monomer is selected from the group consisting of styrene, alpha-methyl styrene, substituted styrene, substituted alpha-methyl styrene and ethylene-unsaturated monomers containing aryl rings. castings.

4. The oil-in-water emulsion of claim 2, wherein the ethylenically unsaturated hydroxyl functional monomer is a hydroxyalkyl acrylate or methacrylate.

5. The oil-in-water emulsion of claim 1, wherein the polyisocyanate crosslinking agent of component (1) includes a urethane adduct of a polyol with a diisocyanate containing at least one tertiary isocyanate group.

6. The oil in water emulsion of claim 5, wherein the polyol is trimethylolpropane.

7. The oil-in-water emulsion of claim 5, wherein the diisocyanate is meta-a, a, a1, 'tetramethylxylylene diisocyanate.

8. A curable film-forming composition derived from an oil in water emulsion including an aqueous medium in which an organic composition has been emulsified including, as the primary film-forming components, a mixture of: (1) a hydrophobic aromatic group containing cross-linking agent polyisocyanate containing at least two isocyanate reactive groups, of which at least one is a tertiary isocyanate group; and (2) a surfactant reactive isocyanate material; wherein the surfactant reactive isocyanate material includes an acrylic copolymer containing active hydrogen having a glass transition temperature of at least 0 ° C, and prepared from a mixture of polymerizable ethylenically unsaturated monomers containing from 5 to 80 weight percent, in based on the total weight of monomer solids used to prepare the copolymer, of an ethylenically unsaturated aromatic monomer, wherein said composition can be cured at ambient temperatures.

9. The composition of claim 8, wherein the mixture of ethylenically unsaturated monomers contains from 5 to 80 weight percent, based on the total weight of monomer solids used to prepare the copolymer, of an ethylenically unsaturated hydroxyl functional monomer.

10. The composition of claim 9, wherein the ethylenically unsaturated aromatic monomer is selected from the group consisting of styrene, styrene-substituted alpha-methyl styrene, substituted alpha-methyl styrene and ethylenically unsaturated monomers containing fused aryl rings.

11. The composition of claim 9, wherein the ethylenically unsaturated hydroxyl functional monomer is a hydroxyalkyl acrylate or methacrylate.

12. The composition of claim 8, wherein the polyisocyanate crosslinking agent of component (1) includes a urethane adduct of a polyol with a diisocyanate containing at least one tertiary isocyanate group.

13. The composition of claim 12, wherein the polyol is trimethylolpropane.

14. The composition of claim 12, wherein the diisocyanate is meta-a, a, a ', a' -tetramethylxylylene-nodiisocyanate.

15. A coating composition composed of multiple components including a base coat deposited from a pigmented film composition and a clear topcoat applied over the base coat in which the clear topcoat is deposited from a clear film-based derivative composition of an oil in water emulsion including an aqueous medium in which an organic composition has been emulsified including, as the primary film-forming components, a mixture of: 1) a hydrophobic aromatic group containing polyisocyanate crosslinking agent containing at least two isocyanate groups reagents, of which at least one is a tertiary isocyanate group; and (2) a surfactant reactive isocyanate material; wherein the surfactant reactive isocyanate material includes an acrylic copolymer containing active hydrogen having a glass transition temperature of at least 0 ° C, and pre-stopped from a mixture of polymerizable ethylenically unsaturated monomers containing from 5 to 80 weight percent , based on the total weight of solids of monomers used to prepare the copolymer, of an ethylenically unsaturated aromatic monomer, wherein said composition can be cured at ambient temperatures.

16. The multi-component composite coating composition of claim 15, wherein the mixture of polymerizable ethylenically unsaturated monomers contains from 5 to 80 weight percent, based on the total weight of monomer solids used to prepare the copolymer, of a hydroxyl monomer ethylenically unsaturated functional.

17. The composite composition of multiple components of claim 15, wherein the ethylenically unsaturated aromatic monomer is selected from the group consisting of styrene, styrene-substituted alpha-methyl styrene, substituted alpha-methyl styrene and ethylenically unsaturated monomers containing rings molten aryl.

18. The composite composition of multiple components of claim 16, wherein the ethylenically unsaturated hydroxyl functional monomer is a hydroxyalkyl acrylate or methacrylate.

19. The multi-component composite coating composition of claim 15, wherein the polyisocyanate crosslinking agent of component (1) includes a urethane adduct of a polyol with a diisocyanate containing at least one tertiary isocyanate group.

20. The multiple component composite coating composition of claim 19, wherein the polyol is trimethylolpropane.

21. The composite composition of multiple components of claim 19, wherein the diisocyanate is meta-a, a, a ', a'-tetramethylxylylene-no-diisocyanate.