MX2008002935A - Coating compositions for adhesion to olefinic substrates - Google Patents

Abstract

An aqueous composition contains an olefinic polymer having an olefin portion that is substantially saturated and anionic functionality imparting water dispersibility. The olefinic polymer can be prepared by reacting a saturated or substantially saturated olefin polymer with a reactant that provides the water-dispersing functionality. The composition can be an adhesion promoter that provides excellent adhesion of subsequent coating layers to olefinic substrates like TPO or an additive in a different coating composition, which may be a curable coating composition, especially a primer composition, to provide excellent adhesion to olefinic substrates like TPO.

Description

COATING COMPOSITIONS FOR ADHESION TO OLEFINIC SUBSTRATES Field of the description This description refers to the compositions that are applied on plastic substrates, particularly thermoplastic polyolefin (TPO) substrates.

BACKGROUND OF THE DESCRIPTION It is often desirable, for decorative or functional purposes, to apply a coating on a plastic substrate. It has been difficult to find coating compositions for some substrates that provide the necessary adhesion at a reasonable price and with appropriate physical properties. It is well known that it is difficult to obtain good adhesion of the paints to olefinic substrates, including thermoplastic polyolefin (TPO) substrates and other modified polyolefin-based materials.

In general, plastic substrates can be coated with curable or thermosetting coating compositions, which cure below the temperatures at which the plastic substrate would deform. Thermosetting coating compositions are widely used in the coating art, particularly for high performance primers and the topcoat layers. The more transparent colored composite coatings have been particularly useful as finished finish coatings for which exceptional gloss, color intensity, image clarity or special metallic effects are desired.

It has been necessary to include one or more additional manufacturing steps to prepare an olefinic substrate for painting so that the coating layer can adhere to the olefinic substrate. According to a frequently used method, one of each layer of an adhesion promoter or tie layer is applied directly to the olefinic substrate. The desired coating or layers are then applied to the adhesion promoter. Such adhesion promoters usually include a chlorinated polyolefin as the main or only component of the vehicle. Another method that has been used to prepare an olefinic substrate for receiving a coating layer is the chemical modification of the substrate surface, for example by pre-flame or corona treatment.

Recently, coating compositions have included significant concentrations of adhesion promoting agents to achieve good adhesion to olefinic substrates. Published International Application WO 97/35937 discloses a composition containing 5-45% by weight resin solids of a substantially saturated polyhydroxylated polydiene polymer having terminal hydroxyl groups. International Publication Number WO 97/35937 and all references mentioned therein are incorporated herein by reference. International Publication 931 discloses that such polymers are the hydrogenated product of dihydroxypolibutadiene produced by anionic polymerization of conjugated hydrocarbon diene capped with two moles of ethylene oxide and terminated with two moles of methanol. (Ethylene oxide produces the oxygenated anion, and methanol provides the hydrogen cation to form the hydroxyl group.) The large amount of this adhesion promoting agent to be included can adversely affect the physical properties and the appearance of the coating. resulting. In addition, compositions containing significant concentrations of the adhesion promoting agent can be separated into phases because the different components are often not very compatible. Reference 937 requires a specific solvent pack which may be undesirable in many cases. The same problems are encountered with other adhesion promoters of the prior art, such as chlorinated polyolefins. It is also known that the inclusion of chlorinated polyolefins in some coating compositions, for example curable coating compositions including acid catalysts, can cause adverse interactions between the different components of the coating composition.

EP 0 982, 337 published March 1, 2000, describes a block copolymer based on olefins having a substantially saturated olefin block and at least one (poly) ester or (poly) ether block. The olefin-based block copolymer can be used in an adhesion promoter to provide excellent adhesion of other coating layers to olefinic substrates such as TPO. The olefin-based block copolymer can also be added, even at low concentrations, to other coating compositions, including curable coating compositions, to provide excellent adhesion to olefinic substrates. The adhesion promoter of EP 0 982 337 offers significant cost advantages over the adhesion promoters based on chlorinated polyolefins and provides adhesion to the most normal coating compositions at modest levels that add little cost.

It would be desirable to provide a lower cost adhesion promoter or adhesion additive with better performance under stringent test conditions. It would also be desirable to have an aqueous adhesion promoter to avoid the considerable organic emissions of previous adhesion promoters of this type.

SUMMARY OF THE DISCLOSURE The present disclosure discloses an aqueous composition containing an olefinic polymer having a substantially subsaturated olefinic portion and at least one ionizable group imparting water dispersibility to the polymer. The functionality that imparts dispersibility in water is ionized by dispersing the polymer. The olefin-based block copolymer can be prepared by reacting a saturated or substantially saturated olefin polymer with a reactant that provides water dispersion functionality to the polymer, wherein the olefin polymer has a functional group reactive with the reactant.

In certain embodiments, the olefin polymer of the aqueous composition is substantially free of hydroxyl groups or has no hydroxyl groups.

In some embodiments, the olefinic polymer has anionic groups.

In some embodiments, the olefin polymer disperses a chlorinated polyolefin resin in the aqueous composition.

The aqueous composition including the olefinic polymer can be used as an adhesion promoter which provides excellent adhesion of subsequent coating layers to olefinic substrates such as TPO. The aqueous composition containing the olefinic polymer can also be used as an additive, even at relatively low levels, in a curable coating composition, especially a primer coating composition, to provide good adhesion of the coating to olefinic substrates such as TPO. The adhesion promoter or coating composition of the invention can be applied directly to an unmodified plastic substrate, in other words to a plastic substrate that does not have pre-treatment to the flame or in corona in any other treatment to chemically modify the surface of the substrate and to which a prior adhesion promoter or coating has not been applied.

In some embodiments in which the aqueous composition containing the olefinic polymer is an additive in a curable coating composition, the olefinic polymer comprises the reactive functionality with the curable component of the coating composition.

Other areas of application will be apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Detailed description The following description is only exemplary and is not intended to limit the present description, application or uses.

The saturated or substantially unsaturated polyolefin (referred to herein as the "saturated polyolefin") that is used to prepare the olefin polymer of the invention preferably has a number average molecular weight of at least about 1000 and in certain embodiments at least about 1500. The saturated polyolefin preferably has a number average molecular weight of up to about 5000, and in certain embodiments up to about 3500.

The saturated polyolefin is reacted with a reactant to provide at least one ionizable functionality that imparts dispersibility in water. The at least one functionality that imparts dispersibility in water can be anionic or cationic. The ionizable groups may be acid groups including carboxylic acid groups, sulfonic acid groups, phosphonic acid groups and phosphoric acid groups; or amino groups, including quaternary amino groups. In general, it is desirable to have at least one functional group that imparts water solubility for each 1000 grams of polyolefin. The functional groups imparting solubility in water can be converted into an adult on the polyolefin by reacting the terminal groups such as the hydroxyl groups and the groups along the polymer backbone, such as residual unsaturated groups or pendant hydroxyl groups. For example, anhydrides such as trimellitic anhydride can react with the hydroxyl groups of the polyolefin. In another example, a hydroxyl group of the polyolefin can be reacted with a semi-cured diisocyanate (i.e., with one of its isocyanate groups that reacted) with a polyacid such as a copolymer of acrylic acid or methacrylic acid or a polyester resin with high functionality acid.

The saturated polyolefin may have one or more additional functionalities that favor dispersibility in water. Non-limiting examples of other functionalities that may also be incorporated to impart dispersibility in water include, without limitation, oxyethylene groups; oxyethylene-co-oxypropylene groups, activated terminal carbamate groups such as the beta- and gamma-carbamyloxy hydroxyalkyl groups; polyacrylamide groups.

In one embodiment, a carboxylic acid group is provided by the reaction of a hydroxyl group on the polyolefin saturated with a cyclic anhydride.

In another embodiment, a hydroxyl group on the saturated polyolefin can react with phosphorus peroxide to produce a phosphate acid. The nitric acid and sulfonic acid groups can likewise be incorporated.

In certain embodiments, the saturated polyolefin is functional hydroxyl. The saturated polyolefin can be converted into the adduct with a polyether block, polyester block or polyurethane block to provide compatibility with the coating layer which is applied over the adhesion promoter or in which the adhesion promoter is placed . In certain embodiments an acrylate block can be used, such as when a polyolefin with epoxide groups is reacted with, for example, an acid-free free radical initiator or when an isocyanate functional polyolefin is reacted with a hydroxyl functional free radical initiator. The initiator group is then used for polymerization by addition of the desired ethylenically unsaturated monomers. In addition, any of the controlled polymerization techniques can be used to incorporate one or two functional groups into a polyacrylate for further reaction with the polyolefin. The polyether polyester block can be added by reacting a saturated polyolefin having hydroxy functionality with a chain extender reagent that is reactive with the hydroxyl groups and polymerizes in a head-to-tail arrangement of the monomer units. The hydroxyl functional olefin forms a block A, while the chain extender reagent forms a block or B blocks. Chain extender reactants such as these include, without limitation, lactones, hydroxy carboxylic acids, oxirane-functional materials, such as alkylene oxides. , and combinations of these. Preferred chain extender reagents are lactones and alkylene oxides, and even more preferred are epsilon-caprolactone, ethylene oxide, propylene oxide and combinations thereof.

The hydroxyl functional olefin polymer can be produced by the hydrogenation of a polyhydroxylated polydiene polymer. Polyhydroxylated polydiene polymers can be produced by anionic polymerization of monomers such as isoprene or butadiene and by crowning the polymerization product with alkylene oxide and methanol, as described in U.S. Patent Nos. 5,486,570, 5,376,745, 4,039,593, and Reissue 27, 145, each of which is incorporated herein by refee. The polyhydroxylated polydiene polymer is considerably saturated by hydrogenation of the double bonds which is at least 90%, preferably at least 95% and even more preferably practically 100% complete to form the olefinic hydroxyl functional polymer. The hydroxyl equivalent weight of the olefin polymer saturated with hydroxyl functionality can be from about 500 to about 20,000.In a preferred embodiment, block A of the olefin-based block copolymer can be represented by the formula: wherein R can be hydrogen or alkyl having from 1 to about 4 carbon atoms, preferably hydrogen or alkyl of 1 to 2 carbon atoms; and wherein X and y represent the molar percentages of the monomer units indicated in the olefinic polymer, the sum of x and y being 100 molar%. In a preferred embodiment, R is hydrogen or ethyl, and x is preferably from about 60 mol% to about 95 mol%, more preferably from about 75% to about 90 mol%.

The olefinic hydroxyl functional polymer is preferably a hydroxyl functional hydrogenated copolymer of butadiene with ethylene, propylene, 1,2-butene and combinations thereof. The olefinic polymers may have a number average molecular weight of preferably from about 1000 to about 10,000, more preferably from 1000 bristle to about 5000, even more preferably from about 1000 to about 3500, and even more preferably from near from 1500 to about 3500. The olefinic polymer also preferably has at least one hydroxyl group on average per molecule. Preferably, the olefinic polymer has from about 0.7 to about 10 hydroxyl groups on average per molecule, more preferably from about 1.7 to about 2.2 hydroxyl groups on average per molecule and still more preferably about two hydroxyl groups on average per molecule. The olefinic hydroxyl functional polymer preferably has terminal hydroxyl groups and an equivalent hydroxyl weight from about 1000 to about 3000. Polydispersities of the molecular weight of less than about 1.2, particularly about 1.1 or less, are preferred for these materials.

The olefinic polymer is preferably a low molecular weight poly (ethylene / butylene) polymer having at least one hydroxyl group. In another preferred embodiment, the polyolefin polyol is a hydrogenated polybutadiene. During the formation of the hydrogenated polybutadiene polyol, part of the butadiene monomer can react head to tail and part can react by a 1,3 polymerization to produce a carbon-carbon skeleton having pendant ethylene groups from the 1,3-polymerization. The relative amounts of the head-to-tail and 1.3 polymerizations can vary widely, with an amount from about 5% to about 95% of the monomer reacting head to tail. Preferably, from 75% bristle to about 95% of the monomer reacts head to tail. Among the preferred hydrogenated polyolefin polyols are those available under the trademark POLYTAIL ™ from Mitsubishi Chemical Corporation, Specialty Chemicals Company, Tokyo, Japan including POLYTAIL ™ H.

While not wishing to be bound by any theory, it is considered that the mechanism that results in the adhesion of the coating to the substrate involves migration of the olefin-based block copolymer to the interface of the olefinic substrate or TPO and an interaction with the olefinic substrate. or TPO. It is considered that the migration and / or interaction is facilitated by the application of heat, such as the heat that is applied to cure the coating composition. The olefin-based block copolymers having narrower polydispersity (ie, closer to the ideal of one), in which the high molecular weight fractions are less than for the materials having similar numerical average molecular weights but wider polydispersity (greater), it is considered that they offer an advantage in better adherence to lower levels of incorporation or effective adhesion obtained in milder conditions (lower temperatures and / or shorter interaction times). The "Polydispersity", also known simply as "dispersity", is defined in the science of polymers as the ratio of the weighted average molecular weight to the numerical average molecular weight. Higher polydispersity numbers indicate a wider distribution of molecular weights, and in particular it means a larger fraction of higher molecular weight species. The olefin-based block copolymer of the invention thus preferably has a narrow polydispersity.

When the olefin polymer polymerizes anionically, it can have a very narrow polydispersity, such as in the order of only about 1.1. Ring-opening reactions of lactones and alkylene oxides or reactions of other materials that are added head-to-tail as hydroxycarboxylic acids tend to produce polymers that are more uniform and have narrow polydispersities. Modification of the olefinic polymer by a head-to-tail reaction such as the ring-opening reaction of a lactone or alkylene oxide compound usually results in a product having a polydispersity of about 1.1 or 1.15, thus practically preserving the Narrow polydispersity of the initial hydroxyl functional olefin material. The block copolymers of the invention preferably have polydispersities of about 1.2 or less, and more preferably have polydispersities of about 1.15 or less.

Again, while not wishing to be bound by the theory, modification of the olefin polymer by the (poly) ester or (poly) ether block or blocks offers significant advantages in providing adhesion of the coatings to the olefinic substrates due to the increased compatibility of the resulting block copolymer to the materials commonly used in these coatings. In addition, the imposition of the (poly) ester or (poly) ether block between the olefinic block and the functional group, such as the hydroxyl group, makes this functional group more accessible for the reaction during the curing of the coating compositions. These principles can be used to optimize the olefin-based block copolymer of the invention for use under specific conditions, or with, or in particular, coating compositions.

In a preferred embodiment, the hydroxyl functional olefin polymer is reacted with a lactone or a hydroxycarboxylic acid to form an olefin-based polymer having terminal blocks (poly) ester. Lactones that can be opened in the ring by an active hydrogen are well known in the art. Examples of the appropriate lactones can be, without limitation, e-caprolaton, β-caprolactone, β-butyrolactone, β-propiolactone, β-butyrolactone, α-methyl-y-butyrolactone, p-methyl-y-butyrolactone, α- valerolactone, d-valerolactone,? -decanolactone, d-decanolactone,? -nonaoicolactone,? -octanonaoic lactone and combinations thereof. In a preferred embodiment, the lactone is e-caprolactone. Lactones useful in the practice of the invention can also be characterized by the formula: wherein n is a positive integer from 1 to 7 and R is one or more H atoms, or substituted or unsubstituted alkyl groups of 1-7 carbon atoms.

The ring-opening reaction of the lactone is usually carried out at elevated temperature (for example 80-150 ° C). When the reactants are liquids, a solvent is not necessary. However, a solvent may be useful to promote good conditions for the reaction even when the reactants are liquid. Any solvent can be used any non-reactive solvent, including polar and non-polar organic solvents, can be used. Examples of the useful solvents may be, without limitation, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone and the like and combinations of these solvents. Preferably a catalyst is present. Useful catalysts may be, without limitation, protonated acids (e.g. octanoic acid, Almberlist® 15 (Rohm &Haas)), and tin catalysts (e.g., stannous octoate), otherwise, the reaction may be initiated by forming a sodium salt of the hydroxyl group on the molecules that react with the lactone ring.

A hydroxycarboxylic acid may also be used in place of a lactone or in combination with a lactone when the compound that reacts with the olefinic hydroxyl functional polymer provides ester blocks. Useful hydrocarboxylic acids can be, without limitation, dimethylhydroxypropionic acid, hydroxystearic acid, tartaric acid, lactic acid, 2-hydroxyethylbenzoic acid, N- (2-hydroxyethyl) ethylenediamine triacetic acid, and combinations thereof. The reaction can be carried out under common esterification conditions, for example at temperatures from room temperature to about 150 ° C, and with catalysts such as, for example, calcium octoate, metal hydroxides such as potassium hydroxide, metals of the group I or group II such as sodium or lithium, metal carbonates such as potassium carbonate or magnesium carbonate (which can be improved by use in combination with crowned esters), organometallic oxides and esters such as dibutyltin oxide, stannous octoate and octoate of calcium, metal alkoxides such as sodium methoxide and aluminum tripidoxide, protic acids such as sulfuric acid or Ph4SbI. The reaction can also be carried out at room temperature with a polymer supported catalyst such as Amberlyst-15® (available from Rohm &; Haas) as described by R. Anand in Synthetic Communications, 24 (19), 2743-47 (1994), the description of which is incorporated herein by reference.

While the polyester segments can likewise be produced with dihydroxy and dicarboxylic acid compounds, it is preferred to avoid these compounds because of the tendency of the reactions including these compounds to increase the polydispersity of the resulting block copolymer. If used, these compounds can be used in limited amounts and preferably be used only after the lactone or hydroxycarboxylic acid reactants have reacted completely.

The reaction with the lactone or the hydroxycaboxylic acid or the oxirane compounds adds at least one monomeric unit such as block B and preferably provides chain extension of the olefinic polymer. In particular, the (poly) ester and / or (poly) ether block appears to affect the polarity and effective reactivity of the terminal group functionality during the curing of the coating. The (poly) ester and / or (poly) ether block also makes the block copolymer based on olefins more compatible with the components of a common curable coating composition. The amount of extension depends on the moles of the alkylene oxide, lactone and / or hydroxycarboxylic acid available for the reaction. The relative amounts of the olefin polymer and the alkylene oxide, lactone and / or hydroxy acid can be varied to regulate the extent of chain extension. The reaction of the lactone ring, or the oxirane ring and / or hydroxycarboxylic acid with a hydroxyl group results in the formation of an ether or ester and a resulting new hydroxyl group which then reacts with another available monomer, thus providing chain extension desired. In the preferred embodiment of the present invention, the equivalents of oxirane, lactone and / or hydroxycarboxylic acid for each hydroxyl equivalent on the olefin polymer are from about 0.5 to about 25, more preferably from about 1 to about 10, in even more preferably from about 2 to about 6. In an especially preferred embodiment, about 2.5 equivalents of lactone reacts for each hydroxyl equivalent on the olefinic polymer.

In another embodiment of the invention, a polyolefin having terminal hydroxyl groups reacts with an oxirane-containing compound to produce terminal blocks (poly) ether. The oxirane-containing compound is preferably an alkylene oxide or cyclic ether, especially preferably a compound selected from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran and combinations thereof. The segments of the alkylene oxide polymer include, without limitation, the polymerization products of ethylene oxide, propylene oxide, 1,2-cyclohexene oxide, 1-butene oxide, 2-butene oxide, 1-oxide. hexene, tert-butylethylene oxide, phenylglycidyl ether, 1-decene oxide, isobutylene oxide, cyclopentene oxide, 1-pentene oxide and combinations thereof. The hydroxyl group of the olefin-based polymer functions as an initiator for the polymerization of base-catalyzed ethylene oxide. The polymerization can be carried out, for example, by charging the hydroxyl-terminated olefin polymer and a catalytic amount of caustic, such as potassium hydroxide, sodium methoxide or potassium tert-butoxide, and adding the alkylene oxide at a rate enough to keep the monomer available during the reaction. Two or more different alkylene oxide monomers can be randomly copolymerized by coincidental addition and block polymerized by sequential addition.

Tetrahydrofuran polymerizes under known conditions to form repeating units: - [CH2CH2CH2CH20] - Tetrahydrofuran is polymerized by a cationic ring-opening reaction using counterpoises such as SbF ~ 6, AsF ~ 6, PF ~ 6, SbCl "6, BF ~ 4, SF3S03 ~, FSO 3 and CIO 4. The initiation is by Formation of a tertiary oxonium ion The polytetrahydrofuran segment can be prepared as a "latent polymer" and terminated by reaction with the hydroxyl group of the olefinic polymer.

After the addition of the polyether or polyester blocks, the terminal hydroxyl group or groups can be converted into adults with the ionizable group, for example by reaction with cyclic anhydride, phosphorus pentoxide, a functional acid compound having an isocyanate group or a functional isocyanate compound having a blocked amino group which is regenerated after the reaction between the isocyanate group and the terminal hydroxyl group.

It is also highly desirable that the olefin-based block copolymer of the invention have functional groups that are reactive with one or more film-forming components of the adhesion promoter, or of the coating composition that is applied over the adhesion promoter. containing the olefin-based block copolymer, or the coating composition to which the olefin-based block copolymer is added. The film-forming components with which the olefin-based block copolymer can react or can be a film-forming polymer or a curing agent. Reactive functional groups on the olefin-based block copolymer can include, without limitation, hydroxyl carbamate, urea, carboxylic acid, and combinations thereof. After the addition of the ether or ester blocks, the block copolymer of the invention has one or more hydroxyl groups, which may be reactive with the film-forming polymer or curing agent. If desired, the hydroxyl groups can be converted to other functional groups, including carbamate, urea, carboxylic acid groups and combinations thereof. In general, this can be achieved by reaction with a polyester, polyether, polyurethane or acrylic polymer with the desired functionality. The carbamate groups according to the invention can be represented by the structure. wherein R is H or alkyl, preferably 1 to 4 carbon atoms. Preferably, R is H or methyl, and more preferably R is H. The urea groups according to the invention can be represented by the structure: wherein R 'and R "are each independently H or alkyl, or R' and R" together form a heterocyclic ring structure. Preferably, R 'and R "are each independently H or alkyl of 1 to 4 carbon atoms, or together they form an ethylene bridge, and more preferably, R' and R" are each independently H. a hydroxyl group can be converted to a carbamate group by reaction with a monoisocyanate (for example methyl isocyanate) to form a secondary carbamate group (ie, a carbamate of the above structure in which R is alkyl) or with cyanic acid (which can be formed in situ by thermal decomposition of urea) to form a primary carbamate group (ie, R in the above formula is H). This reaction preferably occurs in the presence of a catalyst as is known in the art. A hydroxyl group may also react with phosgene and then ammonia to form a primary carbamate group, or by reaction of the hydroxyl with phosgene and then a primary amine to form a compound having secondary carbamate groups. Finally, the carbamates can be prepared by a transesterification approach where the hydroxyl group reacts with a carbamate alkyl (eg, methyl carbamate, ethyl carbamate, butyl carbamate) to form a compound containing the primary carbamate group. This reaction is carried out at elevated temperatures, preferably in the presence of a catalyst, such as a metal organ catalyst (for example dibutyltin dilaurate). A hydroxyl group can conveniently be converted to a carboxylic acid by reaction with the anhydride of a dicarboxylic acid. It is possible and may be desirable to derive the block copolymer based on olefin, hydroxyl functional to have other functional groups than those mentioned, depending on the particular coating composition with which the olefin-based block copolymer will interact.

The olefin-based block copolymer can be dispersed in an aqueous composition containing water and, as an option, organic co-solvents. The ionizable group can be salted before or during dispersion in water. Bases such as ammonia, amines and metal hydroxides. Suitable salt materials for amino groups include acids such as lactic acid, acetic acid, organic sulfonic acids such as para-toluenesulfonic acid and phosphoric acids. It is advantageous in some cases to include in the block copolymer at least one polyethylene oxide segment. The aqueous dispersion can then be applied as an adhesion promoter or added to an aqueous coating composition as an aqueous dispersion of the block copolymer. Otherwise, the block copolymer can be mixed with the film-forming polymer and then dispersed in water together with the film-forming polymer.

If desired, the olefin-based block copolymer can be combined with a chlorinated polyolefin to prepare the adhesion promoter. Some examples of chlorinated polyolefins can be found in US Pat. Nos. 4, 683, 264; 5, 102, 944 and 5, 319, 032. Chlorinated polyolefins are known in the art and are commercially available from different companies including Nippon Paper, Tokyo, Japan, under the name Superchlon; Eastman, Chemical Company, Kingsport, TN under the designation CPO; and Toyo Kasei Kogyo Company, Ltd., Osaka, Japan under the name Hardlen.

Chlorinated polyolefins usually have a chlorine content of at least about 10%, preferably at least about 15% by weight and up to about 40%, preferably up to about 30% by weight. Chlorinated polyolefins having an chlorine content of up to about 24% by weight are preferred. Even more preferred are chlorine contents of up to about 20% by weight. It is also preferred that the chlorine content be from about 15% to about 18% by weight. The chlorinated polyolefin in general can have number average molecular weight from about 2000 to about 150,000, preferably from about 50,000 to about 90,000. Chlorinated olefins having number average molecular weights from about 65,000 to about 80,000 are particularly preferred.

Chlorinated polyolefins can be based on grafted or ungrafted polyolefins such as, without limitation, chlorinated polypropylene, chlorinated polybutylene, chlorinated polyethylene and mixtures thereof. The non-grafted olefinic polymer for chlorination can be homopolymers of alpha monoolefins with 2 to 8 carbon atoms, and the copolymers can be of ethylene and at least one monomer with ethylenic unsaturation such as alpha mono olefins having 3 to 10 carbon atoms, C 1 -C 12 -alkyl esters of unsaturated monocarboxylic acids with 3 to 20 carbon atoms, and unsaturated mono- or dicarboxylic acids with 3 to 20 carbon atoms, and vinyl esters of saturated carboxylic acids with 2 to 18 carbon atoms carbon.

The base resins of grafted copolymers are reaction products of an alpha olefin polymer and a grafting agent. The alpha olefin homopolymer of one or the copolymer of two alpha-olefin monomers with 2 to 8 carbon atoms may include: a) homopolymers such as polyethylene and polypropylene, b) copolymers such as ethylene / propylene copolymers, ethylene / l-butene copolymers, copolymers of ethylene / 4-methyl-1-pentene, copolymers of ethylene / 1-hexene, copolymers of ethylene / 1-butene / 1-octene, copolymers of ethylene / 1-decene, copolymers of ethylene / 4-ethyl-1- hexene and ethylene / 4-ethyl-1-octene copolymers. Chlorinated, grafted polypropylene can be prepared by chlorination in solution of a polypropylene homopolymer modified by graft or propylene / alpha olefin copolymer. Such graft polymerization is usually done in the presence of a free radical catalyst in a solvent that is inert to chlorination. Fluorobenzene, chlorofluorobenzene, carbon tetrachloride and chloroform and the like are useful solvents. Typically, these grafted polypropylenes are those base resins that have been grafted with an alpha, beta-unsaturated polycarboxylic acid or an acid anhydride of an alpha, beta-unsaturated anhydride to form a chlorinated polyolefin modified with acid and / or anhydride. Suitable graft-forming agents generally include maleic acid or anhydride and fumaric acid and the like.

The modified chlorinated polyolefins can include those modified with an acid or anhydride group. Examples of the unsaturated acids that can be used to prepare a modified chlorinated polyolefin include, without limitation, acrylic acid, methacrylic acid, maleic acid, cyclochronic acid, fumaric acid, the anhydrides thereof. The acid content of the chlorinated polyolefin is preferably from about 0.5% to about 6% by weight, more preferably from sow from 1% to about 3% by weight. Acidity values from about 50 to about 100 mg KOH / g may be preferred for the chlorinated polyolefin, particularly for aqueous compositions. Also, the chlorinated polyolefin polymer may be a chlorosulfonated olefin polymer or a mixture of chlorinated polyolefin polymer with the chlorosulfonated olefin polymer, wherein the chlorosulfonation may be effected by reaction of the grafted or ungrafted base resin with a chlorosulfonation agent.

The adhesion promoter compositions of the invention have a weight ratio of the olefin-based block copolymer to the chlorinated polyolefin which can be from about 1:99 to about 99: 1. The weight ratio of the olefin-based block copolymer to the chlorinated polyolefin is preferably from about 1: 3 to about 3: 1. During the preparation of an aqueous dispersion, the block copolymer based on olefin and the chlorinated polyolefin can be combined before the dispersion of the polymers in an aqueous medium. The ionizable groups of the olefin-based block copolymer can be salted before or after the combination of the copolymer with the chlorinated polyolefin.

Adhesion promoting compositions may also include other components such as, for example, and without limitation, crosslinking agents, pigments, customary fillers in coating additives and combinations thereof. Suitable cross-linking agents are reactive with the functionality in the olefin-based block copolymer, which may include ionizable groups (eg carboxylic acid or an amino group having a labile hydrogen) and / or reactive with a component of a coating applied on the adhesion promoter composition of the invention. Suitable pigments and fillers include, without limitation, conductive pigments, including conductive carbon black pigments and conductive titanium dioxide pigments; non-conductive titanium dioxide and carbon pigments, graph, magnesium silicate, ferric oxide, aluminum silicate, barium sulfate, aluminum phosphomolybdate, aluminum pigments and color pigments. Pigments and, optionally, fillers are usually included in a pigment to binder ratio from 0.1 to about 0.6, preferably from about 0.1 to about 0.25. Suitable additives may be, without limitation, agents for flow control or rheology control, tarnish or base agents, catalysts suitable for the reaction of the particular crosslinker, agents for flow control or rheology control, and combinations of these.

In a preferred embodiment, the adhesion promoter is a dispersion that includes only or mainly only the block copolymer based on olefin and as an option the chlorinated polyolefin as the vehicle components. In this embodiment, it is preferred to first apply the adhesion promoter directly to the plastic substrate and then apply a layer of a coating compositions including one or more components reactive with the olefin-based block copolymer or the optionally included chlorinated polyolefin, modified with functional groups such as acid or anhydride, of the adhesion promoter layer. The application of the "wet-on-wet" coating layers is well known in the art.

In an alternative embodiment, the adhesion promoter further includes at least one crosslinking agent reactive with the olefin-based block copolymer and / or the optional chlorinated polyolefin components. The curing agent has, on average, at least about 2 crosslinking functional groups. Suitable curing agents for functional active hydrogen olefin block copolymers include, without limitation, materials having methylol or methylalkoxy active groups, such as plastic amino crosslinking agents or phenol / formaldehyde adducts, curing agents having isocyanate groups, particularly blocked isocyanate curing agents; curing agents having epoxide groups and combinations thereof. Examples of the preferred curing agent compounds include melamine formaldehyde resins (including monomeric or polymeric melamine resin and partially or fully alkylated melamine resin), blocked or unblocked polyisocyanates (eg, toluene diisocyanate, MDI, isophorone diisocyanate, diisocyanate hexamethylene and isocyanurate trimers thereof, which may be blocked for example with alcohols or oximes), urea resins (for example methylol ureas such as urea formaldehyde resin, alkoxy ureas, such as butylated formaldehyde urea resin), polyanhydrides (for example anhydride) polysuccinic), polysiloxanes (for example trimethoxysiloxane) and combinations thereof. Unblocked polyisocyanate curing agents are usually formulated in two pack (2K) compositions, in which the curing agent and the film-forming polymer (in this case, at least one block copolymer) are mixed only briefly before of the application and because the mixture has a relatively short life time. The curing agent may be combinations of these, particularly combinations that include aminoplast crosslinking agents. Aminoplast resins such as melamine formaldehyde resins or urea formaldehyde resin are especially preferred. For this embodiment, of the adhesion promoter, the applied adhesion promoter can be "wet wet" coated with one or more coating compositions, and then all the layers cured together, or the adhesion promoter layer can be partially or completely cured before being coated with any additional coating layer. Curing the adhesion promoter layer before applying an additional coating layer may allow the subsequent coating layer to be applied electrostatically when the adhesion promoter is formulated with a conductive pigment such as conductive carbon black or carbon dioxide. conductive titanium, according to methods known in the art.

Secondly, the ionizable, olefin-based block copolymer can be added to a variety of coating compositions to produce coating compositions having excellent adhesion to plastic substrates, particularly olefinic substrates, including TPO. Compositions in which the combination of the olefin-based block copolymer can be used and include primers, single final finishes, base layers and clear coats. Preferably, the coating composition is aqueous, and the ionizable groups of the olefin-based block copolymer are ionized in dispersion in the coating composition. The coating composition can also be carried by solvents, in which case the ionizable group needs not to be salted. The coating composition can be a powder coating composition, including an aqueous powder slurry coating composition. The coating composition having the added block copolymer can then be applied directly to an uncoated and unmodified olefin-based substrate or other plastic to form a coating layer having excellent adhesion to the substrate.

The coating compositions of the invention preferably include at least about 0.001% by weight of the olefin-based block copolymer, based on the total weight of the non-volatile carrier. In a preferred embodiment, the block copolymer based on olefin is included in the coating compositions in an amount of at least about 3%, more preferably at least about 5% by weight of the total weight of the non-volatile carrier. The block copolymer based on olefin can be included in the non-volatile vehicle of the coating composition in amounts preferably up to about 20% by weight, more preferably up to about 10% by weight of the total weight of the non-volatile vehicle. It is understood that "vehicle" are the resinous and polymeric components of the coating composition, which include film-forming resins and polymers, crosslinkers, other reactive components such as olefin-based block copolymer and other reactive or non-reactive resinous components or polymeric as acrylic microgels.

The coating composition of the invention may contain a wide variety of film-forming resins. At least one crosslinkable resin is included. The resin can be self-crosslinking, but usually a coating composition includes one or more cross-linking agents reactive with the functional groups of the film-forming resin. The film-formed resins for the coating compositions usually have such functional groups as, for example, without limitation, hydroxyl, carboxyl, carbamate, urea, epoxide (oxirane), primary or secondary amine, amido, thiol, silane and others. and combinations of these. The film-forming resin can be any of those used in the coating compositions including, without limitation, acrylic polymers, vinyl polymers, polyurethanes, polyesters (including alkyd), polyethers, epoxies and combinations and copolymers grafted therefrom. Also included are polymers in which one kind of polymer is used as a monomer in the formation of another, such as a polyester-polyurethane, acrylic-polyurethane or a polyether-polyurethane in which a dihydroxy functional polyester, acrylic polymer or Polyether is used as a monomer in the urethane polymerization reaction. Preferred film-forming resins are acrylic polymers, and polyesters including alkyds. Multiple references describe film-forming polymers for curable coating compositions and thus these materials need not be described in greater detail herein.

Film-forming resins can be included in amounts from about 5 to about 99%, preferably from about 20 to about 80% of the total solid carrier of the coating composition. In the case of aqueous compositions, the film-forming resin is emulsified or dispersed in water.

When the coating composition includes a curing agent, or crosslinker, the crosslinker is preferably reactive with the olefin-based block copolymer and the polymer film-forming resin. The curing agent has, on average, at least about 2 crosslinking functional groups, and is preferably one of the crosslinking materials already described above. Plastic amino resins such as melamine formaldehyde resins or urea formaldehyde resins are especially preferred for the resin functional groups which are hydroxyl, carbamate and / or urea. The coating compositions of the invention can be formulated as unicomponent compositions (one pack or 1K) or two-pack (two packets or 2K), as is known in the art.

The adhesion promoter or coating composition that is used in the practice of the invention may include a catalyst to improve the curing reaction. For example, when the aminoplast compounds, especially the monomeric melamines, are used as a curing agent, a strong acid catalyst can be used to improve the curing reaction. These catalysts are well known in the art and include, without limitation, p-toluenesulfonic acid, dinonylnaphthalene disulfonic acid, dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate, butyl phosphate and hydroxyphosphate ester. Strong acid catalysts are often blocked, for example with an amine. Other catalysts that may be useful in the composition of the invention include Lewis acids, zinc salts and tin salts.

A solvent may optionally be included in the coating composition that is used in the practice of the present invention, and preferably at least one solvent is included. In general, the solvent can be any organic solvent and / or water. It is possible to use one or more of a wide variety of organic solvents. The solvent or organic solvents are selected according to the normal methods and with normal consideration. In a preferred embodiment of the invention, the coating composition is aqueous. The coating composition may contain a mixture of water with any of the common co-solvents that are employed in aqueous dispersions.

Additional agents known in the art, for example and without limitation, surfactants, fillers, pigments, stabilizers, wetting agents, rheology control agents (also known as flow control agents), dispersing agents, promoters of the adhesion, UV light absorbers, hindered amine light stabilizers, silicone additives and other surface active agents, et cetera, and combinations thereof may be incorporated in the adhesion promoter or coating composition containing the block copolymer olefin base.

The adhesion promoter and the coating compositions may be coated in an article by any of a number of well-known techniques. These include, without limitation, spray coatings, dip coating, roll coating, curtain coating and the like. Spray coating is preferred for automotive or other large parts.

The inventive combination of the chlorinated polyolefin and the olefin-based block copolymer can be added to a coating composition for final finishing in amounts that do not significantly change the gloss of the final finish. In one application, for example, the block copolymer based on olefins is used in a final finishing composition, in particular a clear coat composition that produces a high gloss cured coating, preferably having a 20 ° gloss (ASTM D523-89 ) or a DOI (ASTM E430-91) of at least 80 that would be appropriate for exterior automotive components.

In another application, the olefin-based block copolymer may be included in a final finishing composition or primer that produces a low gloss coating, such as for coating certain automotive accessory parts. Common low gloss coatings have a gloss of less than about 30 at a 60 ° angle. Low brightness can be achieved by including one or more matt agents. Low-gloss primer compositions are often used to coat automotive accessory parts, such as in a gray or black coating. The low gloss primer is preferably a weatherable composition because the low gloss primer may be the only coating that is applied to these accessory parts. In the case of a weatherable primer, the resins are formulated to be photoresist and the composition may include the normal light stabilizing additives, such as the hindered amine light stabilizers, UV light absorbers and antioxidants.

When the coating composition of the invention is used as a high gloss pigmented paint coating, the pigment can include any of the organic or inorganic compounds or colored materials, fillers, metal leaf or other inorganic materials such as mica or aluminum flakes , and other materials of the kind that the technique usually names as pigments. The pigments are normally used in the composition in an amount of 0.2% to 200%, based on the total weight of the solids of the binder components (ie, a pigment-to-binder ratio of 0.02 to 2). As mentioned above, the adhesion promoters preferably contain at least one conductive pigment such as conductive black carbon pigment, conductive titanium dioxide, conductive graphite, conductive silica based pigment, conductive mica-based pigment, conductive antimony pigment, aluminum pigment or combinations thereof, in an amount that makes the coating produced suitable for electrostatic applications of other coating layers.

Adhesion promoters and coating compositions can be applied at thicknesses that produce dry film or cured film thickness common in the art, such as from 0.01 to about 5.0 mils, (0.254 to about 127 mm). Common thicknesses for the adhesion promoter layers are from about 0.1 to about 0.5 mils (2.54 to about 12.7 mm), preferably from about 0.2 to about 0.3 mils (about 5.08 to about 7.62 mm). Common thicknesses for the primer layers are from about 0.5 to about 2.0 mils (about 12.7 to about 50.8 mm), preferably from about 0.7 to about 1.5 mils (about 17.78 to about 38.1 mm). Common thicknesses of the basecoat layers are from about 0.2 to about 2.0 mils (about 5.08 to about 50.8mm), preferably from about 0.5 to about 1.5 mils (about 12.7 to about 38.1mm). Common thicknesses for clearcoat layers or unicapped final finishes are from about 0.5 to about 3.0 mils (about 12.7 to about 76.2 mm), preferably from about 1.5 to about 2.5 mils (about 38.1 to near and 63.5 mm).

After application to the substrate, the adhesion promoters and coating compositions of the invention are heated to facilitate interaction with the substrate and thus develop the adhesion of the composition applied to the substrate. Preferably, the coated substrate is heated to at least about the softening temperature of the plastic substrate. Adhesion promoters and coating compositions are preferably thermally cured. The curing temperatures will vary depending on the particular blocking groups that are used in the cross-linking agents, however these generally range between 225 ° F and 270 ° F (106 ° C and 131 ° C). The profile of curing temperatures must be controlled to avoid warping or deformation of the TPO subtraction or other plastic substrate. The first compounds according to the present invention are preferably reactive even at relatively low curing temperatures. Thus, in a preferred embodiment, the curing temperature is preferably between 230 ° F and 270 ° F (109 ° C and 131 ° C), and more preferably at temperatures no greater than about 250 ° F (120 ° C). The curing time will vary depending on the specific components that are used and the physical parameters such as the thickness of the layers, however, the common curing times range from 15 to 60 minutes, and preferably 20-35 minutes. The most preferred curing conditions depend on the specific coating composition and the substrate, and can be discovered by direct testing.

The coating compositions of the invention are particularly suitable for coating olefinic substrates including, without limitation, TPO substrates, polyethylene substrates and polypropylene substrates. The coating compositions can also be used, however, to coat other thermoplastic or thermoset substrates including, without limitation, polycarbonate, polyurethane and flexible substrates such as EPDM rubber or thermoplastic elastomers. Such substrates can be formed by any of the processes known in the art, for example, without limitation, injection molding and reaction injection molding, compression molding, extrusion and thermoforming techniques.

The materials and processes of the invention can be used or formed into a wide variety of coated articles including, without limitation, appliance parts, exterior automotive parts and accessory parts, and interior automotive parts and accessory parts.

The invention is further described in the following examples. The examples are only demonstrative and in no way limit the scope of the invention as described and claimed. All parts are parts by weight unless otherwise indicated.

Example of the invention A solution of 100 parts by weight of hexamethylene diisocyanate in 100 parts by weight of methylamyl ketone is maintained under an inert atmosphere in a reactor. One part by weight of dibutyltin dilaurate is added to the reactor. Then, maintaining the reaction temperature below about 50 ° C, 53 parts by weight of glycerin carbonate is slowly added. Once the glycerin carbonate has been incorporated, 540 parts by weight of a polyolefin with hydroxyl equivalent weight of 1200 g / equivalent is added to crown the polyolefin with synthesized cyclic functionalized urethane carbonate prepolymer. Then, 150 parts by weight of methanol are added to the reactor with a stable stream of ammonia gas bubbled into the reactor contents to transform the cyclic carbonate groups into hydroxycarbamate groups. The excess ammonia and methanol are distilled off in vacuo. Finally, 92 parts by weight of trimellitic anhydride are added to the reactor and the content is allowed to complete the reaction of the hydroxyl groups. The product is a polyolefin with carbamate equivalent weight of about 1750 g / equivalent and acid equivalent weight of about 875 g / equivalent.

An aqueous composition is prepared by salting the acid groups with dimethylethanolamine and dispersing the salted product in deionized water. The aqueous dispersion has a pH of about 7.5 and a solids content of about 40% by weight.

The invention has been described in detail with reference to the preferred embodiments thereof. However, it should be understood that it is possible to make variations and modifications within the spirit and scope of the invention and of the following clauses.

Claims (11)

1. An aqueous composition comprising a polymer containing anionic groups, a polymer portion primarily substantially saturated hydrocarbon, and at least one other portion selected from the group consisting of (poly) ester blocks, (poly) alkylene oxide blocks, and combinations of these.

2. The aqueous composition according to claim 1, characterized in that the polymer is practically free of hydroxyl groups.

3. The aqueous composition according to claim 1, further comprises a member selected from the group consisting of surfactants and dispersants.

. The aqueous composition according to claim 3, comprising a surfactant consisting of a block copolymer of poly (ethylene oxide) -co- (propylene oxide).

5. The aqueous composition according to claim 1, characterized in that the other portion comprises a portion of poly (ethylene oxide).

6. The aqueous composition according to claim 5, characterized in that the hydrocarbon portion and the other portion are linked with an ester group.

7. The aqueous composition according to claim 5, characterized in that the poly (ethylene oxide) portion has a weight of at least about 4000 daltons.

8. The aqueous composition according to claim 1, characterized in that the other portion comprises a functionality selected from the group consisting of activated urea groups, activated carbamate groups, amide groups, radicals of polymerized, water-soluble addition monomers and combinations thereof.

9. The aqueous composition according to claim 8, further comprises a poly (ethylene oxide) portion.

10. The aqueous composition according to claim 1, comprising an anionic group.

11. The aqueous composition according to claim 1, comprising an anionic group and poly (ethylene oxide) moiety.