MXPA98002598A - Undisturated hidroxi diester copolymers and their use in compositions of recubrimie - Google Patents

Abstract

A coating composition is described which includes (a) a copolymer including alternating units of (1) an unsaturated diester monomer in which at least one of the esterifying groups includes a hydroxyl group, (2) an alpha-olefin and (3) an unsaturated fluoromonomer, and (b) a curing agent reactive with the hydroxy group. The diester monomer is formed by first opening an anhydride with an alcohol to form a monoester, and then alkoxylating the remaining acid group in the monoester with an epoxy compound to form a second groupster having hydroxy functionality

Description

UNDISTURATED HYDROXY DIESTER COPOLYMERS AND THEIR USE IN COATING COMPOSITIONS BACKGROUND OF THE INVENTION This invention relates to polymers that find utility in coating compositions, more specifically, hydroxy functional polymers that can be cured to form durable coatings by reaction with crosslinking agents that are reactive with hydroxyl groups, such as polyisocyanates. , aminoplasts and anhydrides. EP-A-0 041 209 and 0 015 484 disclose a coating composition that includes (a) a copolymer of a vinyl monomer such as styrene and an unsaturated diester containing hydroxyl groups in the esterifying groups, diester obtained by reacting an anhydride of unsaturated dicarboxylic acid with an alcohol (polyol) and a monoepoxide compound, and (b) a curing agent such as a polyisocyanate, an amine resin or an anhydride. US 4,166,893 discloses a coating composition similar to EP-A-0 041 209 and 0 015 484 in which the unsaturated diester is copolymerized with an alkyl acrylate and a second monomer selected from styrene, vinyl, acrylic classes or methacrylates However, these references do not suggest the use of a third monomer, namely the alpha-olefin when preparing a copolymer in combination with the other two components as in the present invention. COMPENDIUM OF THE INVENTION The copolymer of the present invention includes the polymerization product of an alpha-olefin, a diester of an unsaturated anhydride in which at least one of the esterifying groups includes a hydroxyl group and an additional unsaturated fluoromonomer. The esterification of the anhydride is carried out in two stages. First, the anhydride is opened with an alcohol to form a monoester. In the second step, the monoester is oxyalkylated with an epoxy compound, preferably alkylene oxide, whereby a diester is formed, the second ester group containing a hydroxy group as a product of the reaction with the epoxide. The unsaturated diester is then copolymerized with the alpha-olefin and the unsaturated fluoromonomer to form a copolymer with alternating units of hydroxy functional diester. The regular position of hydroxyl groups along the copolymer appears to improve curing with curing agents reactive with hydroxyl groups, whereby cured coatings are produced which are characterized by good resistance to usual wear. DETAILED DESCRIPTION Unsaturated anhydrides are the preferred starting material for the present invention for their ability to form alternating copolymers with vinyls. Maleic anhydride is preferred due to its availability, but other substituted or unsubstituted anhydrides of dicarboxylic acids can be used. These include, for example, citraconic anhydride, 2,3-dimethyl maleic anhydride, chloromaleic anhydride, dichloro maleic anhydride, and itaconic anhydride. Any unsaturated anhydride having alkyl, aryl, or other substitution may serve the same purpose. Alternatively, a diester of maleic acid or other unsaturated dicarboxylic acid can be used as the starting material, whereby the diester is then transesterified to give a hydroxy functional ester group. Any alkyl, cycloalkyl, aryl or alkaryl alcohol can serve to open the anhydride ring in the first stage of the esterification. As the primary function of this alcohol is merely to open the anhydride, a wide selection of alcohols and phenols can be used. The use of simple alcohols, particularly methanol or ethanol, is preferred. You can also use ether alcohols. The oxyalkylation of the monoester to a diester is carried out by reaction with an epoxy compound, in particular an alkylene oxide such as ethylene oxide or propylene oxide. The use of propylene oxide is preferred because it forms a 2-hydroxy group in the ester group. You can also use materials that contain glycidyl groups to open the anhydride, such as alkyl or aryl glycidyl ethers (for example, butyl glycidyl ether, phenyl glycidyl ether). The unsaturated hydroxy-functional diester produced from the anhydride is copolymerized with alpha-olefins and an unsaturated fluoromonomer. Other copolymerizable monomers may optionally be used and are selected from the group consisting of vinyl aromatics or substituted vinyl aromatics, ring compounds, vinyl ethers, vinyl esters, vinyl acetals, and mixtures thereof. Acrylic and methacrylic compounds may also be included among the vinyl compounds usable in the copolymerization. Other electron-deficient monomers such as dialkyl maleate or dialkyl fumarates may be part of the comonomer component to be copolymerized with the hydroxy-unsaturated diester monomer. These may include dimethyl maleate, dibutyl maleate, dibutyl fumarate, dibenzyl fumarate, ethyl methyl maleate and the like. Alpha-olefins useful as comonomers include the lower alpha-olefins, ie, materials with a carbon chain length of less than 20, preferably carbon chain lengths of 2 to 12, most preferably 4 to 10. Carbon chain lengths less than 6 can be used, but they are not as convenient because they usually involve the use of a pressure reactor. Carbon chain lengths greater than 10 can be used, but are not preferred because they are not handled so easily during processing. Specific examples include ethylene, propylene, isobutene, diisobutylene, 1-hexene, 1-octene, and 1-decene, and mixtures thereof, the preferred materials being 1-hexene and 1-octene. Cycloaliphatic olefins are also suitable and include, for example, cyclobutene, cyclopentene, 1-methylcyclopropene, methylenecyclopentene, cyclohexene, cycloheptene, cyclooctene and mixtures thereof. Unsaturated fluoromonomers include p-fluoro-alphamethylstyrene, p-fluorostyrene, chlorotrifluoroethylene, heptafluoroisopropyl allyl ether, heptafluoroisopropyl methallyl ether and the like. Optional copolymerizable monomers include vinyl compounds selected from aromatic vinyl monomers, preferably styrene, including also substituted styrene compounds. Examples of alpha-substituted vinyl aromatic compounds include vinyl toluene, alpha-methylstyrene, p-isopropyl-alpha-methyl-styrene, p-isopropylstyrene, p-methoxy-alpha-methylstyrene, p-methoxystyrene, p-chloro-alpha- methylstyrene, p-clo-roestirene, p-dimethylamino-alpha-methylstyrene, p-dimethylaminostyrene, and the like. It is also possible to use beta-substituted styrene compounds, such as styrene, beta-methylstyrene, beta-chlorostyrene, beta-methoxy-methylstyrene, beta-methoxystyrene, beta-n-butoxystyrene, beta-isobutoxystyrene, beta-tert-butoxystyrene. , p-methoxy-beta-methylstyrene, p-methyl- (beta-methylstyrene), p-chloro-beta-methylstyrene, and the like. Another class of vinyl monomers that can be used are vinyl ethers, which may contain alkyl, aryl or cycloaliphatic groups with a carbon chain length of 1 to 20. Specific examples of vinyl ethers include alkyl vinyl ethers such as methyl , ethyl, isopropyl, 2-ethylhexyl, n-butyl, isobutyl, t-butyl, 2-chloroethyl, benzyl vinyl ethers, and mixtures thereof. Also suitable are aryl vinyl ethers which include methyl propenyl ether (both cis and trans isomers), phenyl vinyl ether, and mixtures thereof. In addition, 2-phenyl vinyl alkyl ethers or thioethers having a carbon chain length of not more than about 6, wherein the alkyl group can be straight or branched chain can be used. Suitable cycloaliphatic vinyl ethers include cyclopentyl and cyclohexyl vinyl ethers, and mixtures thereof. Additional examples of suitable vinyl ether monomers include divinyl ether, 1,2-dimethoxyethylene, p-dioxene, and conjugated dihydroanisole, and their mixtures. Information regarding the copolymerization of vinyl ethers can be found in J. Poly. Sci., Vol. 48, page 279 (1960) and in Maleic Anhydride by B. C. Trivedi and B. M. Culbertson (Plenum Press, New York and London; 1982). The unsaturated comonomer can also be selected from allyl compounds including allylbenzene, 2-allylphenol, alpha-allylnaphthalene, 3-allylcyclopentene and mixtures thereof. Functionalized allyl compounds bearing functional groups including hydroxyl, amino, cyano, carboxyl, silane, phosphonate, epoxy and ether radicals include alkenyl alcohol, methallyl alcohol, 2-phenylallyl alcohol, 2-methylene propanediol, 1,1-dimethylalilic alcohol , metali-sheet, n-allylacetamide, allyl acetate, trimethylsilylamine, and diethyl acetonyallyl phosponate, N-allylamidazole, 2-allyl pyrrole and mixtures thereof: when an ether group is present in the allyl compound, the ether group can be a alkylic, aryl or functionalized or non-functionalized cycloaliphatic species. Specific examples include glycidyl allyl ether, allyl ketone, metalylacetone, 2-allylcyclohexanone, 1-phenyl-4-pentene-1-one, diallyl ether, and mixtures thereof.

It should be understood that the comonomer component used to copolymerize with the unsaturated hydroxy-functional maleate ester may include mixtures of the alpha-olefin, the unsaturated fluoromonomer and two or more of any of the optional unsaturated monomers described above. The unsaturated comonomer component and the diester component described above react characteristically to produce an alternating copolymer rather than a disordered copolymer. In synthesizing the alternating copolymer, it is preferred to curb the formation of repeating units of the comonomer. In addition, it may be desirable to control the molecular weight of the alternating copolymer. Typically, this is achieved by "de-saturating" the reaction, i.e., adding an amount of initiator to the diester prepared above, then slowly and continuously adding additional initiator and the unsaturated comonomer component to the reaction vessel at a controlled rate such that it slows down the autopolimerization of the unsaturated monomer component. When this procedure is followed, it is believed that the reaction product is predominantly an alternating polymer represented by the structural formula (AxBy) m, where A represents a single unit that includes a diester, B represents a single unit that includes the unsaturated monomer component, x and y are equal to, and m is an integer greater than 1. In other words, the formation is slowed down of alternating copolymers where x or y, or where both x and y are integers greater than 1. It is theoretically possible that some portions along the polymer chain contain repeat units of unsaturated monomer; however, it is believed that these zones can be eliminated essentially by regulating the feed rates of the initiator and the unsaturated monomer component. Minor amounts of repeating units may not have a noticeable effect on the results, and therefore can be tolerated. After having added all the unsaturated monomer component, the reaction mixture is usually maintained at the reaction temperature for a period of time of the order of about 30 minutes to about 8 hours, preferably from about 60 minutes to about 90 minutes, to ensure that the reaction is over. The resulting copolymer solution generally has a solids content, determined at 110 ° C for 60 minutes, from about 40 percent to about 95 percent, preferably from about 60 percent to about 80 percent by weight.

The copolymer of the present invention generally has a number average molecular weight of from about 1,000 to about 100,000, preferably from about 1,000 to about 5,000, more preferably from about 1,500 to about 3,500 as measured by gel permeation chromatography using polystyrene as a standard. The copolymers of the present invention are useful as filigree binders for coating compositions when combined with a curing agent. Typical crosslinking compounds known to those skilled in the art as curing agents include isocyanates, aminoplastics such as melamine-formaldehydes and benzoguanamines, and anhydrides. The coating composition may be a composition of a package, in which case the curing agent is heat-activated, such as a blocked isocyanate or the aminoplastics. The present invention lends itself particularly to the use in compositions of two curing packs at room temperature, wherein the hydroxy functional copolymer is contained in a package and the curing agent, for example, a polyisocyanate, is contained in a separate package. Optionally, a third package including a viscosity reducer can be additionally employed. The separate packages are mixed immediately before applying the coating composition on a substrate. The ability to form a durable wear resistant coating that looks good at or only slightly above room temperature is especially useful for automotive refinishing applications. The coatings of the present invention may be clear or colored, and can serve as primers, base coatings, or top coatings. It has been found to be particularly useful as a clear topcoat applied over a colored basecoat. When the composition is used as a clear coating in a lighter colored composite coating, the pigmented base coat is first applied to the substrate. The basecoat is then allowed to "brighten", ie, it is allowed to stand at temperatures in the range of from room temperature to 80 ° C for about 10 seconds to 30 minutes, before applying a clear topcoat composition. Basecoat compositions are those known in the art as described, for example, in U.S. Patent No. 4,681,811. If the coating composition is to be a color coating, it may include a pigment component of a known type. The pigment component may contain inorganic, organic, metallic, metallic effect, filler and anticorrosive pigments, and mixtures thereof. Suitable inorganic pigments include titanium dioxide, iron oxide, lead chromate, green chromium, cadmium sulfide, lithopone pigment, and the like. Suitable organic pigments include carbon black; yellow, orange, red and brown monoazo, diazo and benzimidazolone; blue and green phthalocyanine; Anthraquinone pigments ranging from yellow to blue; yellow, red and violet quinacridone; red and brown perylene; indigoid reds, blues and violets; thioindigo violets; yellow, orange and red isoindolinone; quinoline yellows, and the like. Suitable metal and metallic effect pigments include aluminum, zinc, lead, bronze, copper, stainless steel and mica flake, and the like. Suitable filler pigments include magnesium silicate clays, smoked or precipitated silicas, barites, fixed white, china clay, and the like. Suitable anticorrosive pigments include lead oxide, zinc chromate, zinc phosphate, micaceous iron oxide, and the like. Mixtures containing any of the pigments described above are also suitable. Optionally, the coatings may also contain a diluent. The diluent serves to reduce the viscosity of the dispersion and to facilitate the wetting of the pigment. Typically, the diluent includes an organic solvent. Suitable organic solvents include ketones such as methyl isobutyl ketone, methyl ethyl ketone, diisobutyl ketone, and the like; esters such as butyl acetate, isobutyl acetate, pentyl propionate, and the like; alcohols such as methanol, ethanol, propanol, butanol, isobutanol, and the like; or glycol ethers such as the monoalkyl ethers of ethylene glycol, diethylene glycol, or propylene glycol, and the like. Although organic solvents are preferred diluents, suitable alternative diluents include unreactive oligomeric or polymeric materials with a viscosity in the range of from about 20 centipoise to about 1,000 centipoise measured with a viscosimeter.

Brookfield at about 22 ° C (72 ° F) and a vitreous transition temperature of less than about 35 ° C as measured by any of the common thermal analytical methods known to those skilled in the art. Specific examples include plasticizers such as tributyl phosphate, dibutyl maleate, butylbenzyl phthalate, dibutyl benzyl phthalate and their mixtures: and silane compounds such as vinyl trimethoxy silane, gammamethacryloxypropyl trimethoxy silane, and mixtures thereof.

Mixtures of organic solvents or mixtures of organic solvents can also be used with the unreactive oligomeric or polymeric diluents, provided that there is no phase separation when the diluents are mixed with the copolymer of the present invention. When present, the diluent is generally used at a level of from about 0.1 percent to about 500 percent, preferably from about 20 percent to about 400 percent. More preferably from about 50 percent to about 200 weight percent, based on percentages in the weight of solids (resin and pigment) present in the composition. Optionally, the coatings may contain an auxiliary polymer. The purpose of the auxiliary polymer is to modify the properties of the coating composition. For example, it is often desirable to increase the solids level of a pigment dispersion or a coating composition without causing a large increase in viscosity. Or it may be desirable to modify the wetting characteristics of the pigment of the vehicle used to prepare the pigment dispersion. Also, it is often desirable to modify some physical properties of the coating composition to which the pigment dispersion is then added, for example the appearance, gloss, moisture resistance, usual wear resistance or chemical resistance of the cured film. A variety of materials are suitable to be used as the auxiliary polymer. These include, but are not limited to, acrylic polymers, polystyrene polymers, acrylonitrile polymers, polyester polymers, epoxy polymers, polyamide polymers, butadiene polymers, polyalkylene polymers, polyalkylene glycol polymers, aminoplast resins, polyurethane polymers, polymers of polysilane, polysiloxane polymers, and the like. In addition, the auxiliary polymer may contain functional groups including, but not limited to, hydroxyl groups, carboxyl groups, amino groups, epoxy groups, phosphate groups, and the like. Mixtures of auxiliary polymers are also suitable. Methods for preparing such auxiliary polymers are known to those skilled in the art of polymer chemistry, and need not be described here. more details. When present, it is preferred that the auxiliary polymer be present at a level of from about 0.10 percent to about 100 percent, preferably from about 1 percent to about 50 percent, more preferably from about 2 percent to about 25 weight percent, based on percentages in the weight of solids of the primary film-forming polymer present in the composition. The coating compositions may contain other optional ingredients, for example, anti-settling additives, pigment wetting additives, gassing inhibitors, corrosion inhibitors, antifoam additives, surface tension modifiers, fungicides, rheology modifiers, waxes, metal passivators, UV light absorbers, antioxidants, UV light stabilizers, and the like. When present, these additives are generally used at a level of from 0.01 percent to 5 percent by weight, based on the percentages of the total solids weight in the composition, although the amounts may vary. according to the special application. The coating composition may contain other optional ingredients, such as inorganic or organic acids or bases and the like. When present, these materials are generally used at a level of from about 0.01 percent to about 50 percent, preferably from about 0.10 percent to about 5 percent by weight, based on percentages in the weight of the film-forming polymer used in the coating composition.

The coating compositions of the present invention can be applied to any of the various substrates to which they adhere, particularly metal or plastic. Optionally, the substrate may have been precoated with a primer coating composition. The compositions can be applied by conventional means, which include brush application, dipping, flow coating, spraying and the like, but preferably, they are applied by spraying. The usual spray techniques and equipment for air spraying can be used. The following examples illustrate various embodiments of the present invention for the purpose of describing the best mode of the invention, but it should be understood that the scope of the invention is not limited to these particular embodiments. Examples 1 and 2 show the copolymerization of the unsaturated hydroxy functional diesters of the present invention with a combination of olefins and fluoromonomeres. The resulting polymers have utility when coating applications that require high durability, such as for exterior architectural components. This type of coating can include curing agents of the melamine type and can be thermally cured. EXAMPLE 1 Polymerization of hydroxyalkyl, propylene, fluoromonomer maleates 419.6 grams of aromatic solvent were charged AROMATIC® 100 in a stirred stainless steel autoclave of 4 liters. The reactor was then pressurized with nitrogen and depressurized twice, leaving a nitrogen pressure of 0.36 kPa. The reactor was heated with stirring to 97 ° C, then adding 168 milliliters of a solution of 209.2 grams of t-aryl peroctoate initiator (LUPERSOL® 575) in 188.3 grams of AROMATIC 100 solvent in 2 hours. During the same two hours, 860 grams of chlorotrifluoroethylene and 694 grams of methyl hydroxypropyl maleate were added. Propylene (570 grams) was introduced in 3 hours, starting at the same time as the other monomers. After finishing the introduction of the initiator and the first two monomers, another 168 milliliters of the initiator solution was introduced for the next 3 hours. During monomer introductions, the pressure reached a maximum of 2840 kPa. The temperature was then maintained at 97 ° C for another half hour, at which time the pressure dropped to 1640 kPa. The product was then vacuum-extracted at 80 ° C for 4 hours to remove residual volatile monomers. The measured solids of the resulting light, slightly yellow solution were 77.7 percent (determined by heating about 1 gram of the liquid in a vacuum oven at 120 ° C). The viscosity was 24,000 centipoise at 25 ° C as measured with a Brookfield viscometer (spindle 4 at 12 rpm). The hydroxyl value of the polymer solution was 75 milligrams KOH per gram of solution. EXAMPLE 2 Polymerization of hydroxyalkyl, isobutylene, fluoromonomer maleates In a polymerization similar to that of Example 1, with introductions of chlorotrifluoroethylene monomer (30 mol%), methyl hydroxypropyl maleate (35 mol%), and isobutylene (35 mol percent) ), the final polymer had final solids of 69.6% and a viscosity of 3750 centipoise (Brookfield viscometer - spindle 4 at 60 rpm). The hydroxyl value was 113.8. The invention has been set forth in connection with specific embodiments in order to describe the best mode for carrying out the invention. However, it should be understood that recourse may be had to other variations and modifications known to those skilled in the art without departing from the scope of the invention defined by the following claims.

Claims (15)

1. CLAIMS 1. A coating composition that includes: (a) a copolymer that includes the polymerization product of (1) an alpha-olefin, (2) an unsaturated diester monomer in which at least one of the esterifying groups includes a hydroxyl group and (3) a monomer containing unsaturated fluorine; and (b) a curing agent reactive with the hydroxy group.
2. 2. The coating composition of claim 1, wherein the diester groups of the copolymer are the product of the esterification reaction of an unsaturated anhydride with an alcohol to form a monoester, followed. by oxyalkylation of the monoester with an epoxy compound whereby an ester with hydroxy functionality is formed.
3. 3. The coating composition of claim 2, wherein the anhydride is selected from the group consisting of maleic anhydride, citraconic anhydride, and its alkyl dialkyl, chloro, and dichloro substitutions, and mixtures thereof.
4. 4. The coating composition of claim 3, wherein the anhydride is selected from the group consisting of maleic anhydride, citraconic anhydride, and mixtures thereof.
5. The coating composition of claim 2, wherein the alcohol is selected from the group consisting of methanol, ethanol, ether alcohols, cyclohexyl alcohol and mixtures thereof.
6. 6. The coating composition of claim 2, wherein the epoxy compound is an alkylene oxide.
7. 7. The coating composition of claim 2, wherein the alkylene oxide is propylene oxide.
8. 8. The coating composition of claim 2, wherein the epoxy compound is a glycidyl ether.
9. 9. The coating composition of claim 1, wherein the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof.
10. 10. The coating composition of claim 9, wherein the alpha-olefin is a C2 to C12 alpha-olefin.
11. 11. The coating composition of claim 9, wherein the alpha-olefin is a C4 to C10 alpha-olefin.
12. 12. The coating composition of claim 1, wherein the curing agent reactive with the hydroxy group is selected from the group consisting of polyisocyanates, aminoplasts, and anhydrides.
13. 13. The coating composition of claim 5, wherein the unsaturated diester monomer is cyclohexyl hydroxypropyl maleate.
14. The coating composition of claim 9, wherein the alpha-olefin is selected from the group consisting of propylene and isobutylene.
15. 15. The coating composition of claim 1, wherein the unsaturated fluoromonomer is chlorotrifluoroethylene.