MX2008007749A - Methods for improving coating adhesion - Google Patents

Abstract

Methods for improving adhesion between a coating and a substrate using compositions comprising chlorinated polyolefin and a compound comprising ethylene vinyl acetate are disclosed.

Description

METHODS FOR IMPROVING THE ADHESION OF A COATING FIELD OF THE INVENTION The present invention relates to methods for improving adhesion between a coating and a substrate, comprising applying to the substrate a composition including a chlorinated polyolefin and a compound comprising ethylene vinyl acetate . BACKGROUND INFORMATION Many substrates have one or more coatings applied to them that generally have a decorative and / or protective function. Problems often arise associated with the adhesion of the coatings to the substrate, particularly in the case of certain substrates made of thermoplastic or thermosetting polymeric materials. Said coatings, once applied, may flake or crack or need to be removed from the substrate due to deterioration produced by time, chemical exposure, mechanical stress or similar factors. This happens especially with flexible substrates. Therefore, improved adhesion between substrates and coatings is desirable. SUMMARY OF THE INVENTION The present invention relates to methods for improving the adhesion between a coating and a substrate, comprising applying to the substrate, a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is an ethylene vinyl acetate foam ("EVA gum"). The present invention further relates to methods for improving adhesion between a substrate and a coating, comprising applying to the substrate a composition comprising: (a) a chlorinated polyolefin; Y (b) a compound comprising ethylene vinyl acetate, wherein the substrate is polyurethane and the composition does not include epoxy. The present invention further relates to methods for improving adhesion between a substrate and a coating, comprising applying to the substrate a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is fiberglass reinforced plastic. The present invention further relates to methods for improving adhesion between a substrate and a coating, comprising applying to the substrate a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is metallic. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to methods for improving the adhesion between a coating and a substrate, comprising applying to the substrate, a composition comprising a chlorinated polyolefin and a compound comprising ethylene vinyl acetate. Sometimes, this composition is referred to as "adhesion-promoting composition", "adhesion promoter" and its variants. The substrate can be EVA rubber, polyurethane, plastic reinforced with glass fiber and / or metal. In certain embodiments, such as when the substrate is polyurethane, the composition does not include epoxy, for example, epoxy resins. Any chlorinated polyolefin can be used in the present invention if it reaches the chlorine content required below. Suitable chlorinated polyolefins include polyethylene, polypropylene, an ethylene-propylene copolymer, polyisobutylene, polybutene and an ethylene vinyl acetate copolymer. The chlorinated polyolefin may have a content of chlorine between 10 and 65 weight percent, for example, between 18 and 30 weight percent, based on the total weight of the monomer. Commercially available chlorinated polyolefins include, for example, HARDLEN 15 LLB (chlorine content: 30% by weight), HARDLEN 14 LLB (chlorine content: 27% by weight), HARDLEN 14 ML (chlorine content: 26.5% by weight) and HARDLEN BS-40 (chlorine content: 40% by weight) (Toyo Kasei KK products), SUPERCHLON 832 (chlorine content: 27% by weight), SUPERCHLON 773 H (chlorine content: 32% by weight) weight) and SUPERCHLON L-206 (chlorine content: 32% by weight) (Nippon Seichi KK products) and CP 730-1, AP 550-1, CP-516-2, CP 153-2 (chlorine content: between 18 and 23% by weight) (Eastman products). The compositions of the present invention further comprise a compound comprising ethylene vinyl acetate ("EVA") having an EVA content (in weight percent) between 9 and 40, for example, between 25 and 32 weight percent. The phrase "a compound comprising EVA" and similar phrases refers to the EVA polymer itself or to polymers comprising an EVA monomer and one or more other reactive monomers. Such polymers include EVA and vinyl alcohol copolymers. When EVA is introduced with other monomers in polymer form, the amount used in the polymer is used to determine the percentage of EVA in the composition. The phrase "compound comprising EVA", in accordance with the present invention, specifically excludes a carboxyl-modified EVA resin and / or an EVA copolymer and a graft polymer of a carboxylic acid, such as, for example, an unsaturated dicarboxylic acid and EVA and / or an EVA copolymer. The composition may also include a solvent. Suitable solvents include water, organic solvent / s and / or mixtures thereof. Suitable solvents include glycols, ether glycol alcohols, alcohols, ketones, aromatics such as xylene and toluene, acetates, mineral spirits, naphies and / or mixtures thereof. "Acetates" include ether glycol acetates. In certain embodiments, the solvent is a non-aqueous solvent. The term "non-aqueous solvent" and similar terms mean that less than 50 percent of the solvent is water. For example, less than 10 percent or even less than 5 percent of the solvent can be water. It should be understood that mixtures of solvents, including or excluding water in an amount less than 50 percent, can constitute a "non-aqueous solvent". In certain embodiments of the invention, HPA free solvents are used. As used herein, the term "HPA free" refers to materials that are not on the list of HPAs (42 U.S.C. 7412). The compositions used in the present invention can be prepared, for example, by adding the chlorinated polyolefin and a compound comprising ethylene vinyl acetate to a solvent, for example, with stirring. The chlorinated polyolefin can generally comprise between 1 and 5 weight percent of the total composition, for example, between 3 and 4 percent. The EVA can, generally, comprise between 1 and 5 weight percent of the total composition, for example, between 3 and 4 weight percent. The chlorinated polyolefin and / or the compound comprising EVA can take the form of a solution, for example, comprised within a range between 0.1 and 25 weight percent of chlorinated polyolefin and / or compound comprising EVA. Any suitable solvent can be used in both the chlorinated polyolefin solutions and those of the compound comprising EVA, for example, any of those described above. It will be appreciated that the chlorinated polyolefin and the compound comprising EVA are mixed together in the composition and not polymerized. In certain embodiments, the compositions used in the present invention, specifically, exclude melamine resin. In other embodiments, they specifically exclude optical brighteners, chlorinated rubbers, isocyanate, for example, polyisocyanate and / or epoxy resins.

The compositions used in the present invention may further comprise a graft copolymer in which a chlorinated polyolefin and an acrylic polyol are grafted together. Suitable chlorinated polyolefins are those described above; The chlorinated polyolefin used in the copolymer can be the same or different from the other chlorinated polyolefin. Any acrylic polyol, for example, those described in US Pat. No. 6,316,119 in column 2, lines 51-61, can be used and prepared as described in said patent, incorporated herein by reference. The graft copolymer can be prepared according to any means known in the art, such as those described in U.S. Patent No. 5,955,545. The copolymer can comprise a chlorinated polyolefin and an acrylic polyol in a molar ratio of 1: 20, for example 1: 10. When used in the present compositions, the copolymer can generally comprise between 1 and 10 weight percent of the total composition, for example, between 1 and 5 weight percent. In certain embodiments, the adhesion promoter consists essentially of the chlorinated polyolefin and a compound comprising EVA and, optionally, a chlorinated polyolefin / acrylic polyol graft. The adhesion promoter compositions may also comprise one or more additives, for example, colorants, crosslinkers, extenders, UV absorbers, light stabilizers, plasticizers, surfactants, leveling agents, adhesion promoters, rheology modifiers, light stabilizers. of hindered amine and wetting agents. If used, these additives generally comprise up to 0.5 percent by weight of the total weight of the composition. The adhesion promoter composition of the present invention may also include a colorant. As used herein, the term "colorant" means any substance that imparts color and / or other opacity and / or other visual effect to the composition. The coloring any suitable form may be added to the coating, for example, discrete particles, dispersions, solutions and / or flakes. A single dye or a mixture of two or more dyes may be used in the coatings of the present invention. Exemplary colorants include pigments, dyes and inks, for example those used in the paint industry listed by the Dry Color Manufacturers Association (DCMA) (Association of Dry-Color Manufacturers), as well as special effects compositions. A colorant can include, for example, a finely divided solid powder which is insoluble but can be wetted under conditions of use. A colorant can be organic or inorganic and can agglomerate or not. The colorants can be incorporated into the coatings by the use of a ground vehicle, for example, a ground acrylic vehicle, whose use is familiar to the person skilled in the art.

Pigments and / or exemplary pigment compositions include, but are not limited to, crude pigment of carbazole dioxazine, azo, monoazo, disazo, naphthol AS, salt type (flakes), benzimidazolone, condensation, metal complex, isoindolinone, isoindoline and polycyclic phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indantrone, anthrapyrimidine, flavantrone, pyrantrone, anthratrone, dioxazine, triarylcarbonium, quinophthalone pigments, diketo red pyrrole red ("DPPBO red"), dioxide titanium, carbon black and mixtures thereof. The terms "pigments" and "colored fills" can be used interchangeably. Exemplary dyes include, but are not limited to, those having solvent and / or aqueous base such as, for example, green fíalo or blue fíalo, iron oxide, bismuth vanadate, anthraquinone, perylene, aluminum and quinacridone. Exemplary inks include, but are not limited to, pigments dispersed in water-based or water-miscible carriers such as, for example, AQUA-CHEM 896 marketed by Degusta Inc., CHARISMA COLORANTS and MAXITONER INDUSTRIAL COLORANTS marketed by Achúrate Dispersions division of Eastman Chemical, Inc. As noted above, the colorant may take the form of a dispersion including, but not limited to, a dispersion of nanoparticles. The nanoparticle dispersions may include one or more nanoparticle colorants and / or highly dispersed coloring particles that produce the visible color and / or opacity and / or desired visual effect. The nanoparticle dispersions may include dyes such as pigments or dyes having a particle size of less than 150 nm, for example, less than 70 nm or less than 30 nm. The nanoparticles can be produced by grinding organic or inorganic master pigments with a grinding medium having a particle size of less than 0.5 nm. The nanoparticle dispersions and methods for making them are detailed in U.S. Patent No. 6,875,800 B2, which is incorporated herein by reference. Nanoparticle dispersions can also be produced by crystallization, precipitation, gas phase condensation and chemical wear (ie, partial dissolution). In order to minimize re-agglomeration of the nanoparticles within the coating, a dispersion of resin coated nanoparticles can be used. As used herein, a "resin-coated nanoparticle dispersion" refers to a continuous phase in which discrete "composite microparticles" comprising a nanoparticle and a resin coating on the nanoparticle are dispersed. Exemplary dispersions of resin-coated nanoparticles and methods for making them are detailed in U.S. Patent Application No. 10 / 876,315 filed June 24, 2004, which is incorporated herein by reference and US Patent Application No. 10 / 876,031 filed on June 24, 2004, which is also incorporated herein by reference.

Exemplary special effects compositions that can be used in the coating of the present invention include pigments and / or compositions that produce one or more effects on the appearance of the coating, for example, reflectance, pearlescence, metallic reflections, phosphorescence, fluorescence, photochromism, photosensitivity, thermochromism, goniochromism and / or color changes. Other special effects compositions can provide other perceptible properties such as opacity or texture. In a non-limiting embodiment, the special effect compositions can produce a color change, so that the color of the coating changes when viewed from different angles. Exemplary color effect compositions are detailed in U.S. Patent No. 6,894,086 B2, incorporated herein by reference. The color effect compositions may include transparent coated mica and / or synthetic mica, coated silica, coated alumina, a transparent liquid crystal pigment, a liquid crystal coating and / or a composition in which the interference results from a differential of the refractive index within the material and not the differential of said index between the surface of the material and the air. In certain non-limiting embodiments of the compositions of the present invention, a photosensitive composition and / or photochromic composition that reversibly alters its color when exposed to one or more light sources may be used. The photochromic and / or photosensitive compositions can be activated by exposure to radiation of a specified wavelength. When the composition is excited, the molecular structure varies and said altered structure exhibits a new color that is different from the original color of the composition. When exposure to radiation is interrupted, the photochromic and / or photosensitive composition can return to a resting state in which the original color of the composition returns. In a non-limiting embodiment, the photochromic and / or photosensitive composition may be colorless in the non-excited state and exhibit color in I was excited. The complete color change can appear in a lapse between milliseconds and several minutes, for example, between 20 seconds to 60 seconds. Exemplary photochromic and / or photosensitive compositions include photochromic dyes. In a non-limiting embodiment, the photosensitive and / or photochromic composition can be associated with and / or at least partially bound by, for example, covalent bonding, to a polymer and / or polymeric materials of a polymerizable component. In contrast to some coating compositions in which the photosensitive composition can migrate out of the coating and crystallize within the substrate, the photosensitive and / or photochromic composition associated with and / or at least partially bound to a polymer and / or polymerizable component in accordance with a non-limiting embodiment of the present invention, it has minimal migration out of the coating. The photosensitive compositions and / or exemplary photochromic compositions and methods for preparing them are detailed in US Patent Application No. 10 / 892,919, filed July 16, 2004 and incorporated herein by reference. In general, a colorant may be present in the coating composition in an amount sufficient to impart the desired visual and / or color effect. If dye is used, it may comprise between 1 and 65 weight percent of the present compositions, for example, between 3 and 40 weight percent or, between 5 and 35 weight percent, the percentage being weight based on the total weight of the compositions. As mentioned above, the present invention relates to methods for improving adhesion between a substrate and a coating, which comprises applying to the substrate any of the adhesion promoter compositions described above. The coating may be any subsequent coating added for decorative, protective and / or functional purposes, such as those described below. It will be appreciated that the present invention relates to the improvement of adhesion between a substrate and a coating and not between two substrates, for example, two components of a footwear. The methods of the present invention are particularly effective in promoting adhesion on EVA rubber, polyurethane, fiberglass reinforced plastic and / or metal. It will be appreciated that many of these substrates are flexible. As used herein, "flexible substrate" and similar terms refer to substrates that can withstand mechanical stresses, such as bending or stretching and similar actions, without observing a significant irreversible change. In certain embodiments, flexible substrates are compressible substrates. "Compressible substrate" and similar terms refer to substrates capable of withstanding a compression deformation and recovering substantially the same shape once the compression deformation has ceased. The term "compression deformation" means a mechanical pressure that reduces the volume of a substrate at least temporarily in at least one direction. The "EVA rubber" may comprise open and / or closed cell foam. "Open cell foam" means that the foam comprises a plurality of interconnected air chambers; "Closed cell foam" means that the foam comprises discrete closed pores. The EVA rubber may include flat sheets or sheets or molded EVA rubber, for example, between soles for shoes. Different types of EVA rubber can have different types of surface porosity. The molded EVA rubber may comprise a dense surface or "skin" while the flat sheets or plates may exhibit a porous surface. The polyurethane substrates according to the present invention include thermoplastic urethane based on aromatic, aliphatic or hybrid polyesters (the hybrid examples are silicone polyether or urethane polyester and urethane silicone carbonate) or based on polyether, for example, DESMOPAN, TEXIN, PURSIL and CARBOSIL. "Fiberglass reinforced plastic" includes any plastic to which fiberglass was added and / or applied. "Plastic" means any thermoplastic or thermosetting synthetic non-conductive material, including olefins thermoplastics such as polyethylene and polypropylene, thermoplastic urethane, polycarbonate, sheet molding compound, injection molding compound, acrylonitrile-based materials, nylon and similar materials. The "metals" include all metals such as, for example, Mg, Al, Ti and the like. The substrates coated according to the present invention are not polyolefins or gum. All or part of the substrate can be coated using the adhesion promoting compositions, which can be applied by any means known in the art. Examples include but are not limited to, brush application, rubbing, spraying, dipping or fluid coating. The adhesion promoter can be used in any amount to obtain an improved adhesion between the substrate and any of the additional coating layers applied. According to the needs of the user and the particular substrate used, the substrate can be pre-treated before application of the compositions to promote adhesion. Said pre-treatment may include, for example, plasma treatment, flame treatment, abrasive sanding, UV irradiation and / or chemical cleaning with a solvent. After the application of the adhesion-promoting composition, it can be cured, for example, by evaporation at room temperature and then optional baking. The baking operation can be carried out, for example, at a temperature comprised within a range between 50 and 60 ° C, for 15 to 25 minutes. It is within the possibilities of the trained in the practice of art, the determination of the proper conditions of curing, particularly if the substrate on which the adhesion promoter is applied is taken into account. The thickness of the adhesion promoter dry film may be in the range of 0.01 to 1.0 mils (0.25 to 25 microns) and is generally 0.1 to 0.4 mils (2). 5 to 10 microns).

Typically, a primer and / or base coat composition different from the adhesion promoter composition may be subsequently applied on the adhesion promoter described herein. The primer and / or base coat may be pigmented or non-pigmented. Optionally, a clear coating composition can be applied on the base layer. The primer layer and / or the basecoat and / or clearcoat may be applied after baking the film of the adhesion promoter composition or it may be applied "wet on wet" before baking; that is, the adhesion promoter can be cured or not, before the application of the subsequent coating layers. Any primer, basecoat and / or clearcoat can be used depending on the needs of the user, the particular substrate and the particular use of the substrate. The adhesion of the subsequent coating layers (ie, primer, basecoat and / or clearcoat) will be increased when compared to a coated substrate without the adhesion promoter described herein. Thus, it should be understood that the adhesion promoter composition described herein, can be applied as a separate layer and not as an additive of another coating. As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, quantities and percentages may be read as if preceded by the word "approximately", even if this term does not expressly appear. . Any numerical range quoted here is intended to include all subranges involved. The plural includes the singular and vice versa. For example, while the description has been described in terms of "a" chlorinated polyolefin, "a" compound comprising ethylene vinyl acetate, "" an "acrylic polyol and" a "solvent, one or more of these ingredients may be used. Furthermore, as used herein, the term "polymer" refers to pre-polymers, oligomers, homopolymers and copolymers, the prefix "poly" refers to two or more.

EXAMPLES The following examples illustrate the invention and should not be considered, in any way, limiting thereof. Example 1 An adhesion promoter according to the present invention was prepared by mixing the following with a tongue-type blade for about five minutes. Table 1 * Sol vente: 50/50 methylcyclohexane / n-Ba ref. 05 041-91 'CPO 343-1 from Eastman, Pm 10,000-30,000 2ELVAX 150W from DuPont.

Between soles for ethylene-vinyl shoes were cleaned with a mixture of solvents (MIBK, ethyl acetate, DOWANOL, PMA in a molar ratio of 42:40:18). The solvents were allowed to air dry. The adhesion promoter was applied with a brush or wiped with a cloth, as indicated in Table 2. The promoter can also be applied by spraying. The coatings were subjected to forced drying for 10 minutes. A base layer and a transparent layer were applied. The base coat was 2K (VIVAFLEX) SPECTRACRON FLEX black-colored (casual black) with a transparent topcoat, both marketed by PPG Industries, Inc. The coatings were dried at room temperature for 10 minutes and cured for 20 minutes at 55 ° C. Adhesion was controlled in cross directions (cross-hatch adhesion) after 24 hours in accordance with ASTM D3359. As can be seen in Table 2 below, the solvent mixture alone did not produce adhesion. The adhesion promoters of the present invention gave good adhesion. Table 2 * Sol vente: 50/50 methylcyclohexane / n-BA ref. 05-041-94. ** ND: not performed Example 2 Adhesion promoters were prepared according to Example 1 using the following components: 3 CPO 343-1"ELVAX 150W * Parts per cent The samples of Table 3 were applied by spraying on EVA rubber, nylon reinforced with glass fiber and Mg-Al alloy. The samples were dried by forced drying for about 10 minutes. A 2K base coat of pigmented isocyanate / hydroxyl, as described in U.S. Patent Application No. 11 / 155,154, was applied by spraying; a transparent layer was applied over it and both layers were cured at around 52 ° C. Adhesion was controlled in cross directions (cross-hatch adhesion) after 24 hours in accordance with ASTM D3359. As can be seen in Table 4, excellent adhesion was observed for all substrates. Table 4 Although particular embodiments of the invention have been described for illustrative purposes it will be obvious to the skilled person that numerous variations may be made in the details thereof, without departing from the invention as defined in the appended claims.

Claims (15)

1. CLAIMS 1. A method for improving adhesion between a substrate and a coating, characterized in that it comprises applying to said substrate, a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is ethylene vinyl acetate foam.
2. 2. A method for improving adhesion between a substrate and a coating, characterized in that it comprises applying to the substrate a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is polyurethane and the composition does not include epoxy.
3. 3. A method for improving adhesion between a substrate and a coating, characterized in that it comprises applying to the substrate, a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is a glass fiber reinforced plastic.
4. 4. A method for improving adhesion between a substrate and a coating, characterized in that it comprises applying to the substrate, a composition comprising: (a) a chlorinated polyolefin; and (b) a compound comprising ethylene vinyl acetate, wherein the substrate is a metal.
5. 5. The method according to any of claims 1, 2, 3 or 4, characterized in that the composition further comprises a non-aqueous solvent.
6. 6. The method according to any of claims 1, 2, 3 or 4, characterized in that the composition is free of PAHs.
7. 7. The method according to any of claims 1, 2, 3 or 4, characterized in that the chlorinated polyolefin comprises chlorinated polypropylene. The method according to any of claims 1, 2, 3 or 4, characterized in that the chlorinated polyolefin has a chlorine content of between 18 and 30 weight percent. The method according to any of claims 1, 2, 3 or 4, characterized in that the compound comprising ethylene vinyl acetate comprises vinyl acetate EVA. The method according to any of claims 1, 2, 3 or 4, characterized in that the composition comprises an ethylene vinyl acetate content comprised between 25 and 40 weight percent. The method of claim 1, characterized in that the dry film thickness of the composition is 0.2 to 0.4 mils (5 to 10 microns). 12. The method of claim 2, characterized in that the plastic is nylon. The method of claim 3, characterized in that the polyurethane is thermoplastic urethane. The method of claim 1, characterized in that the composition further comprises a chlorinated polyolefin and an acrylic polyol. 15. The method according to any of claims 2, 3 or 4, characterized in that the composition further comprises a graft copolymer comprising a chlorinated polyolefin and an acrylic polyol.