MXPA99004956A

MXPA99004956A - Aqueous protective coating agent

Info

Publication number: MXPA99004956A
Application number: MXPA/A/1999/004956A
Authority: MX
Inventors: Frigge Eva
Original assignee: Herberts Gmbh 42285 Wuppertal De; Hoechst Ag 65929 Frankfurt De
Priority date: 1996-11-28
Filing date: 1999-05-27
Publication date: 2000-09-04

Abstract

The invention relates to an aqueous coating agent, which contains as binding agents in the form of aqueous polymer dispersions the following:A) 50 to 90 wt%of one or more thermoplastic copolymers of at least one C2-C4 olefin and of at least one vinyl ester of a C2-C11 monocarboxylic acid, wherein olefin(s) and vinyl ester are present in a weight ratio from 10:90 to 40:60 and together account for at least 80 wt%of the copolymer;B) 10 to 50 wt%of one or more thermoplastic (meth)acryl copolymer, which are free from comonomers with nitrile and amide groups and which consist of at least 50 wt%(meth)acrylic acid esters from C1-C18 alcohols, and C) 0 to 30 wt%of one or more copolymers different from A) and B), wherein each wt%relates to the resin solid body and complement each other to form 100 wt%.

Description

AQUEOUS WATER COATING PROTECTOR FIELD OF THE INVENTION This invention relates to an aqueous coating medium which is suitable for protecting high quality merchandise, particularly for protecting the lacquer surface of motor vehicles, especially new vehicles during assembly, transport and storage, for example. The dry coating medium for forming coatings which after use can be easily removed as a thin sheet type film. The present invention also relates to a method of applying the coating medium according to the invention.

BACKGROUND OF THE INVENTION Aqueous coating means are known for the purpose of protecting high quality merchandise. For example, new motor vehicles are coated with protective lacquers of this type during storage and transport. These protective lacquers can be easily removed from the object, for example by washing with suitable cleaning solutions, or they can be detached like a thin sheet that is generally discarded by incineration.

Temporary aqueous coating means are known in the form of thin sheets which can be peeled off after use. For example, they may be aqueous coating media based on copolymers containing comonomers such as (meth) acrylonitrile or (meth) acrylamide. After use, the coatings that are formed are detached like a thin sheet and burned, after which toxic gases are released. Other examples include aqueous coating media based on copolymers containing comonomers comprising groups that have been converted to anionic groups by amine neutralization. The amines volatilize when the coating layers dry. Aqueous protective lacquers are known from WO 90 08 165, which can be peeled off as a thin film type film after performing its protective function. Its area of application is the temporary protection of very different parts of buildings against various types of dirt that are typical of construction operations during construction work. These protective aqueous lacquers contain a polymer dispersion as a binder vehicle, which may comprise acrylate resins, polyvinyl alcohol, ethylene / vinyl acetate copolymers and vinyl copolymers and acrylic comonomers, which may each be present on their own or in a convenient mix.

DESCRIPTION OF THE INVENTION The object of the present invention is to provide aqueous coating means that can be removed as a thin sheet, for the protection of high quality merchandise, particularly for the conservation of motor vehicles. The coating medium must contain as few volatile organic substances as possible, and in particular it must meet the requirements of the motor vehicle industry, in particular it must protect the lacquer surface of new vehicles during assembly, transport and storage, against dirt and formation of water spots and regions recorded due to acid rain, for example. This object is achieved by the provision of an aqueous coating medium containing, as binder vehicles in the form of polymeric aqueous dispersions, A) 50 to 90% by weight of one or more thermoplastic copolymers of at least one C2 olefin -C4 and at least one vinyl ester of a C2-C1 1 monocarboxylic acid, wherein the olefin and the vinyl ester or the vinyl esters are present in a weight ratio of 10:90 to 40:60, and together make at least 80% by weight of the copolymer, B) 10 to 50% by weight of one or more thermoplastic (meth) acrylic copolymers that are free of comonomers containing nitrile and amide groups, and at least 50% by weight of which consists of (meth) acrylic acid esters of C1-C18 alcohols, and C) O at 30% by weight of one or more copolymers that are different from A) and B), wherein the percentages by weight are given with respect to the resin solids in each case and add up to 100% by weight. The component A) of the aqueous coating medium according to the invention is an aqueous polymer dispersion based on a thermoplastic copolymer of at least one C2-C4 olefin and at least one vinyl ester of a C2-C11 monocarboxylic acid, wherein the olefin and the vinyl ester or the vinyl esters are present in a ratio of 10:90 to 40:60, and together they make at least 80% by weight of the thermoplastic copolymer. Examples of C2-C4 olefins include ethene, propene, 1-butene, 2-butene and isobutene; Ethene is preferred. Examples of vinyl esters include vinyl acetate, vinyl propionate and vinyl versatate; vinyl acetate is particularly preferred. The versatatos that can be used are vinyl esters of versatic acids. Versatic acids are commercial names of the Shell company for strongly branched saturated monocarboxylic acids comprising alkyl side chains and tertiary carboxyl groups. These versatic acids are C-5 to C-11 alkanoic acids. The olefin and vinyl esters are present in the thermoplastic copolymer of component A) in a weight ratio of 10:90 to 40:60; the weight ratio of the olefin (s) to vinyl ester or vinyl esters is preferably between 15:85 and 30:70. The copolymer can contain 0 to 20% by weight of olefinically unsaturated monomers which are incorporated by polymerization and which are different from the C2-C4 olefins and the vinyl esters of a C2-C1 monocarboxylic acid. Comonomers which are They contain nitrile and amide groups. Also preferably excluded are water-soluble comonomers and comonomers containing groups which can be converted to ionic groups by neutralization, for example (meth) acrylic acid. If the copolymer of component A) contains acidic comonomers, these are present only in a small amount, for example corresponding to an acid number of the copolymer of component A) of less than 10, preferably less than 5 mg of KOH / g. Apart from their olefinically unsaturated double bond, the comonomers which are optionally contained in a quantitative proportion of up to 20% by weight, preferably do not comprise other functional groups such as epoxide groups, hydroxyl groups and alkoxysilane groups, for example. The comonomers which are avoided in particular in this respect are those which, due to their functionality or functionalities, can result alone or in combination with other comonomers, the internal entanglement of the copolymer of component A) or entanglement between the copolymer of component A ), the (meth) acrylic copolymer of component B) and / or the copolymer of component C). In this respect and hereafter, the term "(meth) acrylic" denotes methacrylic and acrylic. Examples of comonomers without additional functional groups other than their olefinically unsaturated double bond which are optionally contained in the copolymer of component A) include alkyl esters such as dialkyl esters of fumaric acid or dialkyl esters of maleic acid, comprising an alkyl of C1 -C6, for example, such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, tertbutyl or hexyl; aromatic vinyl compounds such as styrene or vinyltoluene; and particularly esters of (meth) acrylic acid of C1-C18 monoalcohols such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate, isopropyl, isobutyl (meth) acrylate, terbutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 3,5,5- (meth) acrylate trimethylhexyl, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate. The copolymers of the aqueous polymer dispersion A) are preferably synthesized exclusively from olefin or C2-C4 olefins and from vinyl ester or esters of a C2-C11 monocarboxylic acid. Ethene / vinyl acetate copolymers are particularly preferred. The glass transition temperature of the thermoplastic copolymer of component A), determined in accordance with DIN 53 765, is preferably between 0 and 30 ° C, preferably between 5 and 20 ° C. The aqueous polymer dispersion A) is preferably produced by emulsion polymerization. Examples of the ethylene / vinyl acetate emulsion copolymer which is particularly preferred as component A), include commercially available products (see Karsten, Lackrohstofftabellen, Curt R. Vincentz Verlag, Hanover, 1992, 9th Edition, Section 9.2.2, page 301). Component B) of the aqueous coating medium according to the invention is an aqueous polymer dispersion based on a (meth) acrylic thermoplastic copolymer containing no comonomers comprising nitrile and amide groups, and at least 50% by weight of the which consists of (meth) acrylic acid esters of C1-C18 alcohols. Examples of (meth) acrylic acid esters of C1-C18 alcohols include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylate, isopropyl, isobutyl (meth) acrylate, terbutyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 3,5,5- (meth) acrylate trimethylhexyl, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate. The thermoplastic (meth) acrylic copolymer of component B) may contain 0 to 50% by weight of olefinically unsaturated monomers which are incorporated by polymerization and which are different from the (meth) acrylic acid esters of C1-C18 alcohols, wherein comonomers comprising nitrile and amide groups are excluded. Also preferably excluded are water-soluble comonomers and comonomers containing groups which can be converted to ionic groups by neutralization, for example (meth) acrylic acid. If the (meth) acrylic copolymer of component B) contains acid comonomers, these are present only in a small amount, for example corresponding to an acid number of the (meth) acrylic copolymer of component B) of less than 10, preferably less than 5 mg KOH / g. Apart from their olefinically unsaturated double bond, the comonomers which are optionally contained in a quantitative proportion of up to 50% by weight, preferably do not comprise other functional groups such as epoxide groups, hydroxyl groups and alkoxysilane groups, for example. The comonomers which are avoided in particular in this respect are those which, due to their functionality or functionalities, can result alone or in combination with other comonomers, the internal entanglement of the (meth) acrylic copolymer of component B) or entanglement between the (meth) acrylic copolymer of component B), the copolymer (or copolymers) of the component (s) A) and / or C). Examples of comonomers without additional functional groups other than their olefinically unsaturated double bond that are optionally contained in the (meth) acrylic copolymer of component B) include alkyl esters such as dialkyl esters of fumaric acid or dialkyl esters of maleic acid, comprising a C 1 -C 6 alkyl, for example, such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, tertbutyl or hexyl; aromatic vinyl compounds such as styrene or vinyltoluene; or vinyl esters of a C 2 -C 1 monocarboxylic acid, such as vinyl acetate, vinyl propionate and versic acid vinyl ester. The (meth) acrylic copolymers of the aqueous pplimeric dispersion B) are preferably synthesized exclusively from esters of (meth) acrylic acid of C1-C18 alcohols. The glass transition temperature of the thermoplastic (meth) acrylic copolymer of component B), determined in accordance with DIN 53 765, is preferably between 0 and 30 ° C, preferably between 5 and 20 ° C. The (meth) acrylic polymeric aqueous dispersion B) is preferably produced by emulsion polymerization. Examples of the (meth) acrylic copolymer dispersion B) include commercially available products.

(See Karsten, Lackrohstofftabellen, Curt R. Vincentz Verlag, Hanover, 1992, 9th Edition, Section 13.6.1, page 363). The component C of the aqueous coating medium according to the invention comprises copolymer dispersions which are different from A) and B), wherein the selection of the monomer is subject to the same restrictions as for the copolymers of component A) and the copolymers methacrylics of component B), that is, monomers comprising nitrile and amide groups are preferably excluded. Also preferably excluded are water-soluble monomers and monomers containing groups which can be converted into ionic groups by neutralization, for example (meth) acrylic acid. If the copolymer of component C) contains acidic monomers, these are present only in a small amount, for example corresponding to an acid number of the copolymer of component C) of less than 10, preferably less than 5 mg of KOH / g. Furthermore, it is preferable not to contain monomers which, apart from their olefinically unsaturated double bond, comprise another functional group such as epoxide groups, hydroxyl groups and alkoxysilane groups, for example. The monomers that are avoided in particular in this respect are those which, due to their functionality or functionalities, can result either on their own or in combination with other comonomers, internal interlacing of the copolymer of component C) or crosslinking between the component copolymer C), the copolymer of component A) and / or the methacrylic copolymer of component B).

In a preferred embodiment, the thermoplastic copolymers of component A) and / or the copolymers of component C) are free of comonomers comprising nitrile and amide groups. Aqueous coating means are then obtained which have the additional advantage that the thin films obtained after use do not give off toxic gases or only a very small amount of toxic gases, by incineration. Components A), B) and C) are mixed in a resin solids ratio of 50 to 90 parts of A): 10 to 50 parts of B): 0 to 30 parts of C), where the parts add up to 100% Component C) is preferably omitted, and components A) and B) alone are mixed in a ratio of resin solids of 50 to 90 parts of A): 10 to 50 parts of B), preferably 55 to 85 parts of A ): 15 to 45 parts of B). A pH adjustment can be made, which may possibly be convenient but usually not necessary, of the mixtures of the components A), B) and optionally C), whose mixtures are generally slightly acidic, by means of organic bases or inorganic materials such as ammonia, alkali metal carbonates, alkali metal hydroxides, amines or amino alcohols, for example. In this regard, inorganic bases are preferred. In addition to the binder vehicle components A), B) and optionally C), the coating medium according to the invention can contain other customary paint additives in amounts which are customary for lacquers. Examples include light stabilizers, leveling agents, protective colloids, emulsifiers, plasticizers, antifoaming agents, biocides, partitioning agents and dyes, and also pigments in quantitative coverage and non-covering ratios, for example for marking purposes, and in particular the coating medium may contain rheology controlling agents or agents with a thickening effect. Examples of the latter which may be contained in the coating medium according to the invention in quantitative proportions of 0.1 to 5% by weight, preferably 0.5 to 3% by weight, with respect to the content of solid resin in the medium of coating according to the invention, include microdispersed hydrated silica, inorganic layered silicates, water-soluble cellulose ethers such as hydroxyethylcellulose, methylcellulose or carboxymethylcellulose, as well as synthetic polymers comprising ionic groups and / or groups with an associative effect, such as polyvinyl alcohol, polymethacrylic acid, polyvinylpyrrolidone and also polyurethane or ethoxylated polyacrylates which have been modified to render them hydrophobic. Preferably, the silicones are avoided in the aqueous coating medium according to the invention. The aqueous coating medium according to the invention has a relatively high solids content, for example 30 to 60% by weight, preferably 40 to 55% by weight, which is optionally adjusted by the addition of deionized water. It may also optionally contain a water-thinnable organic solvent which is added as a coalescence aid, for example, the content of which is less than 5% by weight, for example, preferably less than 2% by weight with respect to the solids of resin. The aqueous coating medium according to the invention preferably should not contain organic solvent. The aqueous coating medium according to the invention is applied as a temporary protective coating to high quality merchandise. The application of the coating medium produced in this way can be carried out in the usual way, by roller or brush application, for example.; it is preferably applied by spraying or pouring. The drying of the coatings produced from the coating medium can be carried out over a wide range of temperatures, between 20 and 80 ° C, for example. The coating medium according to the invention is suitable for coatings that adhere to a multitude of substrates such as wood, textile goods, plastics, glass, ceramics and to metals and metals lacquered in particular. Preferably, an adhesion-free, non-interlocked protective coating is obtained. The aqueous coating medium is preferably sprayed to give a dry coating thickness of 30 to 100 μm, preferably between 40 and 80 μm. A preferred embodiment is the application of the coating medium according to the invention in which it is applied by spraying or pouring, to give a dry coating thickness of 30 to 100 μm, preferably between 40 and 80 μm, to the coating of lacquer External baking of a multilayer lacquer coating of motor vehicle, and dried at temperature between 20 and 80 ° C to give an adhesion-free, non-interlaced, closed protective coating. A particular advantage of the aqueous coating medium according to the invention is that considerable dry coating thicknesses * can be obtained with it, even when applied by depositing them only once, particularly in only one spray step. After performing its function as a thin sheet type film, the coating can be detached from the protected object, without special measures, and subsequently can be stored or disposed by incineration, without the release of toxic gases and without constituting a threat to the environment. The coating layers produced from the aqueous coating medium according to the invention are characterized by a protective effect corresponding to the requirements. Reliably protect the lacquer surface of objects to be protected from the etching phenomenon due to environmental effects, for example due to acid rain, and in this way they are particularly suitable as temporary coatings for new vehicles.

EXAMPLE 1 19 parts of an aqueous copolymer dispersion of 50% by weight of acrylic acid esters with a glass transition temperature of 12 ° C (determined in accordance with DIN 53 765) were mixed with 3 parts of a commercially available partition agent. Then, it was mixed with vigorous stirring with 78 parts of an aqueous dispersion of ethene / vinyl acetate copolymer at 53% by weight with a glass transition temperature of 13 ° C (determined in accordance with DIN 53 765). The aqueous coating medium produced in this manner, which had a viscosity according to DIN 53211-4 of 32 seconds, was applied by means of spray to give a dry coating thickness of 50 μm, to a test panel which had been coated with a typical lacquer structure of automotive mass production (consisting of a sizing, a sizing finisher, a base lacquer and an external transparent lacquer coating). Drying for 10 minutes at 80 ° C (oven temperature) gave a closed protective coating of matte silk, which after cooling could be detached as a thin film type film from the clear lacquer surface without special measures. It was shown in a test that with 36% sulfuric acid at 65 ° C, the clear lacquer surface that was provided with the protective coating, was protected from a first visually perceptible damage effect for at least 30 minutes longer than the surface of the unprotected transparent lacquer.

EXAMPLE 2 parts of the coating medium of example 1 were placed in a container, and mixed, using a solvent, with a commercially available part of polyurethane associative thickener (Borchigel L 75 N, 54%). The batch was completed in portions with an additional 80 parts of the coating medium of Example 1. The viscosity according to DIN 53211-4 was 90 seconds.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. A method for producing temporary protective coatings by applying an aqueous coating medium to a substrate, characterized in that an aqueous coating medium is used which contains, as binder vehicles in the form of aqueous polymer dispersions, A) 50 to 90% by weight of one or more thermoplastic copolymers of at least one C2-C4 olefin and at least one vinyl ester of a C2-C11 monocarboxylic acid, wherein the olefin and the vinyl ester or the vinyl esters are present in a by weight from 10:90 to 40:60, and together they make at least 80% by weight of the copolymer, B) 10 to 50% by weight of one or more thermoplastic (meth) acrylic copolymers that are free of comonomers containing nitrile and amide groups, and at least 50% by weight of which consists of esters of (meth) acrylic acid of C 1 -C 18 alcohols, and C) 0 to 30% by weight of one or more copolymers which are different from A) and B), where the percentages by weight are given with respect to the resin solids in each case and add up to 100% by weight, and wherein an outer coat of baked lacquer of a lacquer coating of motor vehicle, serves as a substrate.

2. A method according to claim 1, characterized in that the thermoplastic copolymer of component A contains ethene as a C2-C4 olefin and / or vinyl acetate as a vinyl ester of a C2-C11 monocarboxylic acid.

3. A method according to claim 1 or 2, characterized in that the weight ratio between the olefin or the olefins and the vinyl ester or esters is between 15: 85 and 30: 70. 4.- A method according to any of the claims 1 to 3, characterized in that the comonomers containing nitrile and amide groups are excluded for the thermoplastic copolymer of component A) and / or for the copolymers of component C). 5. A method according to any of claims 1 to 4, characterized in that the thermoplastic copolymer of component A) is synthesized exclusively from olefin or C2-C4 olefins and vinyl ester or esters of a C2-C2 monocarboxylic acid C11 6. A method according to any of claims 1 to 5, characterized in that the thermoplastic copolymer of component A) and / or the thermoplastic (meth) acrylic copolymer of component B), have a glass transition temperature between 0 and 30 ° C. 7. A method according to any of claims 1 to 6, characterized in that the aqueous coating medium has a solids content of 30 to 60% by weight. 8. A method according to any of claims 1 to 7, characterized in that the aqueous coating medium contains one or more rheology control agents and / or agents with a thickening effect. 9. A method according to any of claims 1 to 8, characterized in that the aqueous coating medium is applied by spraying or pouring. 10. A method according to any of claims 1 to 9, characterized in that the aqueous coating medium is applied to give a dry coating thickness of 30 to 100 μm. 1. A method according to any of claims 1 to 10, characterized in that the aqueous coating medium is applied by spraying or pouring to an outer baked-on lacquer coating of a multilayer lacquer coating of motor vehicle for give a dry coating thickness of 30 to 100 μm, and dry at temperatures between 20 and 80 ° C to form a protective, adhesion-free, non-interlocked protective coating.