Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/50—Multilayers
  • B05D7/52—Two layers
  • B05D7/53—Base coat plus clear coat type
  • B05D7/532—Base coat plus clear coat type the two layers being cured or baked together, i.e. wet on wet
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2451/00—Type of carrier, type of coating (Multilayers)

Definitions

• the invention relates to a method for producing a multilayer protective and / or decorative coating on a substrate surface, in which.
• a pigmented aqueous coating composition which contains a water-dilutable emulsion polymer as film-forming material, is applied to the substrate surface as the base coating composition
• the invention also relates to water-thinnable coating compositions, water-thinnable emulsion polymers and a process for the preparation of water-thinnable ones
• Emulsion polymers are Emulsion polymers.
• the process in question can only be used to produce metallic effect coatings with a good metallic effect if the aqueous base coating compositions used are composed in such a way that they - especially with the aid of automatic painting systems - in relatively thin, fast-drying compositions Layers can be applied to the substrate and, after carrying out process steps (3) and (4), contain the metal pigment particles in parallel alignment with the substrate surface.
• the aqueous base coating compositions must be composed in such a way that the base layer of the stoved metallic effect coating adheres well to the substrate and the transparent cover layer adheres well to the base layer. Furthermore, the aqueous base coating compositions must be composed in such a way that the baked-on metallic effect coating shows no matting, delamination phenomena or even bubbles after exposure to a constant temperature in condensed water.
• aqueous base coating compositions exhibit high storage stability.
• DE-A-3 628 124 discloses aqueous base coating compositions which contain, as film-forming material, a mixture of a water-thinnable emulsion polymer and a water-thinnable polyurethane resin. These base coating compositions do not optimally meet the requirements set out above.
• the object on which the present invention is based is to provide aqueous base coating compositions which are suitable for the process in question and which optimally meet the requirements set out above.
• the reaction conditions being chosen so that the emulsion polymer obtained has a number-average Has molecular weight of 200,000 to 2,000,000 and where there s the ethylenically unsaturated monomer or monomer mixture used in the first stage and the type and amount of the ethylenically unsaturated monomer or monomer mixture used in the second stage are selected such that the emulsion polymer obtained has a hydroxyl number from 2 to 100 and the difference - ⁇ is 10 to 170 ° C.
• the water-thinnable emulsion polymers used according to the invention can be prepared by a two-stage emulsion polymerization in an aqueous medium in the known apparatus, for example in a stirred kettle with a heating and cooling device.
• the monomers can be added in such a way that a solution of all of the water, the emulsifier and part of the initiator is introduced and the monomer or monomer mixture and separately therefrom, but in parallel the rest of the initiator is slowly added at the polymerization temperature.
• the first stage it is preferred in the first stage to add the monomer or monomer mixture in the form of a pre-emulsion and in the second stage to add the monomer or monomer mixture in bulk, i.e. without adding water and emulsifier and adding the initiator separately, but in parallel. It is particularly preferred in the first stage to first produce a seed polymer from part (generally about 30% by weight of the total pre-emulsion to be used) of the pre-emulsion to be used in the first stage and then the rest of the one in the first Add the pre-emulsion to be used.
• the polymerization temperature is generally in the range from 20 to 100 ° C., preferably 40 to 90 ° C.
• the quantitative ratio between the monomers and the water can be selected so that the resulting dispersion has a solids content of 30 to 60% by weight, preferably 35 to 50% by weight.
• An anionic emulsifier is preferably used alone or in a mixture as the emulsifier.
• anionic emulsifiers are the alkali metal salts of sulfuric acid half-esters of alkylphenols or alcohols, furthermore the sulfuric acid half-esters of oxyethylated alkylphenols or oxyethylated alcohols, preferably the alkali metal salts of the sulfuric acid half-ester of a nonylphenol reacted with 4-5 mol ethylene oxide per mol, alkyl or Aryl sulfonate, sodium lauryl sulfate, sodium lauryl ethoxylate sulfate and secondary sodium alkane sulfonates, the carbon chain of which contains 8-20 carbon atoms.
• the amount of the anionic emulsifier is 0.1-5.0% by weight, based on the monomers, preferably 0.5-3.0% by weight.
• a nonionic emulsifier of the type of an ethoxylated alkylphenol or fatty alcohol for example an addition product of 1 mol of nonylphenol and 4-30 mol of ethylene oxide, can be used in a mixture with the anionic emulsifier.
• a peroxide compound is preferably used as the radical-forming initiator.
• the initiator is water-soluble or monomer-soluble.
• a water-soluble initiator is preferably used.
• Suitable initiators are the customary inorganic compounds, such as ammonium persulfate, potassium persulfate, ammonium or alkali metal peroxydiphosphate and organic peroxides, such as e.g. Benzoyl peroxide, organic peresters, such as perisopivalate, partly in combination with reducing agents, such as sodium disulfite, hydrazine, hydroxylamine and catalytic amounts of accelerators, such as iron, cobalt, cerium and vanadyl salts, preferably alkali metal or ammonium peroxydisulfates.
• reducing agents such as sodium disulfite, hydrazine, hydroxylamine
• accelerators such as iron, cobalt, cerium and vanadyl salts, preferably alkali metal or ammonium peroxydisulfates.
• the redox initiator systems disclosed in EP-A-107300 can also be used.
• the first stage 10 to 90, preferably 35 to 65 parts by weight of an ethylenically unsaturated monomer or a mixture of ethylenically unsaturated monomers are emulsion polymerized.
• T ⁇ glass transition temp. of homopoly
• T G1 glass transition temperature
• Examples of monomers which can be used in the first stage are: vinylaromatic hydrocarbons, such as styrene, *. -Alkylstyrene and vinyltoluene, esters of acrylic acid or methacrylic acid, in particular aliphatic and cycloaliphatic acrylates or methacrylates with up to 20 carbon atoms in the alcohol radical, such as methyl, ethyl, propyl, butyl, hexyl, ethylhexyl, stearyl , Lauryl and cyclohexyl acrylate or methacrylate, acrylic and / or methacrylic acid, acrylic and / or methacrylamide, N-methylolacrylamide and / or N-methylolmethacrylamide, hydroxyalkyl esters of acrylic acid, methacrylic acid or another * -, p-ethylenically unsaturated Carboxylic acid such as 2-hydroxyethyl acrylate, 2-hydroxyprop
• ethylenically unsaturated monomers or mixtures of ethylenically unsaturated monomers which are essentially free from hydroxyl and carboxyl groups preference is given to using ethylenically unsaturated monomers or mixtures of ethylenically unsaturated monomers which are essentially free from hydroxyl and carboxyl groups.
• substantially free is intended to mean that it is preferred to use monomers or monomer mixtures which are free from hydroxyl and carboxyl groups, but that the monomers or monomer mixtures used are also used in small amounts (for example as a result of Verun ⁇ cleanings) may contain hydroxyl and / or carboxyl groups.
• the content of hydroxyl and carboxyl groups should preferably be at most so high that a polymer produced from the monomer or monomer mixture used in the first stage has an OH number of at most 5 and an acid number of at most 3.
• components (a1) that can be used are: cyclohexyl acrylate, cyclohexyl methacrylate, alkyl acrylates and alkyl methacrylates with up to 20 carbon atoms in the alkyl radical, such as methyl, ethyl, propyl, butyl, hexyl, ethylhexyl , Stearyl and lauryl acrylate and methacrylate or mixtures of these monomers.
• component (a2) can be used, for example, vinylaromatic hydrocarbons such as styrene, ' ⁇ -alkylstyrene and vinyltoluene, acrylic and methacrylamide, and acrylic and metha crylnitril or mixtures of these monomers.
• vinylaromatic hydrocarbons such as styrene, ' ⁇ -alkylstyrene and vinyltoluene, acrylic and methacrylamide, and acrylic and metha crylnitril or mixtures of these monomers.
• the monomer or monomer mixture used in the first stage and the monomer or monomer mixture used in the second stage are selected in such a way that the emulsion polymer obtained has a hydroxyl number of 2 to 100, preferably has from 10 to 50 and the difference T Q1 - T Q2 is 10 to 170, preferably 80 to 150 ° C.
• Examples of monomers which can be used in the second stage are: vinylaromatic hydrocarbons, such as styrene,--alkylstyrene and vinyltoluene, Esters of acrylic acid or methacrylic acid, in particular aliphatic and cycloaliphatic acrylates or methacrylates with up to 20 carbon atoms in the alcohol radical, such as methyl, ethyl, propyl, butyl, hexyl, ethylhexyl, stearyl, lauryl and cyclohexyl acrylate or methacrylate, acrylic and / or methacrylic acid, acrylic and / or methacrylamide, N-methylolacrylamide and / or N-methylolmethacrylamide, hydroxyalkyl esters of acrylic acid, methacrylic acid or another ⁇ ,
• a mixture is preferably formed in the second stage
• (b2) 1 to 20, preferably 5 to 15% by weight of a monomer carrying at least one hydroxyl group which can be copolymerized with (bl), (b3) and (b4) or a mixture of such monomers
• (b3) 0 to 8, preferably 2 to 6% by weight of a monomer carrying at least one carboxyl or sulfonic acid group and copolymerizable with (bl), (b2) and (b4) or a mixture of such monomers and
• (b4) 0 to 25, preferably 2 to 15% by weight of a further monomer which can be copolymerized with (bl), (b2) and (b3) or a mixture of such monomers used, where. di.e sum of the parts by weight of (bl),
• component (bl) e.g. are used: cyclohexyl acrylate, cyclohexyl methacrylate, alkyl acrylates and alkyl methacrylates with up to 20 carbon atoms in the alkyl radical, such as e.g. Methyl, ethyl, propyl, butyl, hexyl,
• hydroxyalkyl esters of acrylic acid, methacrylic acid or another A, l-ethylenically unsaturated carboxylic acid e.g. are used: hydroxyalkyl esters of acrylic acid, methacrylic acid or another A, l-ethylenically unsaturated carboxylic acid. These esters can be derived from an alkylene glycol which is esterified with the acid, or they can be obtained by reacting the acid with an alkylene oxide.
• hydroxyalkyl esters examples include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate or 4-hydroxybutyl methacrylate.
• esters of other unsaturated acids e.g. Ethacrylic acid, crotonic acid and similar acids with up to about 6 carbon atoms per molecule can also be used.
• Acrylic acid and / or methacrylic acid and / or acrylamidomethylpropanesulfonic acid are preferably used as component (b3).
• component (b4) can be used: vinyl aromatic hydrocarbons, such as styrene, ⁇ . Alkyl styrene and vinyl toluene, acrylic and methacrylamide and acrylic and methacrylonitrile or mixtures of these monomers.
• the emulsion polymer used according to the invention should have a number average molar mass (determination: gel permeation chromatography using polystyrene as standard) of 200,000 to 2,000,000, preferably 300,000 to 1,500,000.
• base coating compositions also contain a water-dilutable polyurethane resin as the film-forming material.
• the base coating compositions according to the invention preferably contain water-thinnable, urea-containing polyurethane resins which have a number average molecular weight (determination: gel permeation chromatography using polystyrene as the standard) of 1000 to 60-0000, preferably 1500 to 50,000 and an acid number of 5 to 70, preferably 10 to 30 and can be prepared by reaction, preferably chain extension, of prepolymers containing isocyanate groups with polyamines and / or hydrazine.
• a number average molecular weight determination: gel permeation chromatography using polystyrene as the standard
• the prepolymer containing isocyanate groups can be prepared by reacting polyalcohols having a hydroxyl number from 10 to 1800, preferably 50 to 500, with excess polyisocyanates at temperatures up to 150 ° C., preferably 50 to 130 ° C., in organic solvents which are not containing iso- cyanates can react.
• the equivalence ratio of NCO to OH groups is between 1.5 and 1.0 to 1.0, preferably between 1.4 and 1.2 to 1.
• the polyols used to prepare the prepolymer can be of low molecular weight and / or high molecular weight and they can contain inert anionic groups.
• Low molecular weight polyols can be used to increase the hardness of the polyurethane. They have a molecular weight from 60 to about 400 and can contain aliphatic, alicyclic or aromatic groups. Amounts of up to 30% by weight of the total polyol constituents, preferably about 2 to 20% by weight, are used.
• 1,6-hexanediol trimethyl-olpropane, castor oil or hydrogenated castor oil, di-tri-ethyl-olpropane ether, pentaerythritol, 1,2-cyclohexanediol, 1,4-cyclo- 5 hexanedimethanol, bisphenol A, bisphenol F, neopentyl glycol, hydroxypivalic acid neopentyl glycol ester , hydroxyethylated or hydroxypropylated bisphenol A, hydrogenated bisphenol A and mixtures thereof.
• a high proportion of a predominantly linear polyol with a preferred hydroxyl number of 30 to 150 should be added.
• Up to 97% by weight of the total polyol can consist of saturated and unsaturated polyesters and / or polyethers with a molecular weight Mn of 400 to 5000.
• polyether diols such as poly (oxyethylene) glycols, poly (oxypropylene) glycols and / or poly (oxybutylene) glycols.
• the selected polyether diols should not introduce excessive amounts of ether groups, otherwise the polymers formed will swell in water.
• the preferred polyether diols are poly (oxyropropylene) glycols in the molar mass range Mn from 400 to 3000.
• Polyester diols are prepared by esterification of organic dicarboxylic acids or their anhydrides with organic diols or are derived from a hydroxycarboxylic acid or a lactone.
• polyols or polycarboxylic acids with a higher valency can be used to a small extent.
• the dicarboxylic acids and diols can be linear or branched aliphatic, cycloaliphatic or aromatic dicarboxylic acids or diols.
• the diols used to prepare the polyesters consist, for example, of alkylene glycols, such as ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and other diols, such as dimethylcyclohexane.
• alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and other diols, such as dimethylcyclohexane.
• the acid component of the polyester consists primarily of low molecular weight dicarboxylic acids or their anhydrides with 2 to 30, preferably 4 to 18, carbon atoms in the molecule.
• Suitable acids are, for example, o-phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, cyclo-hexane dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, glutaric acid, hexachloroheptane dicarboxylic acid, and tetrachlorophthalic acid, or tetrachlorophthalic acid.
• their anhydrides if they exist, can also be used.
• polyester polyols When forming polyester polyols, smaller ones can also be used Amounts of carboxylic acids with 3 or more carboxyl groups, for example trimellitic anhydride or the adduct of maleic anhydride with unsaturated fatty acids, are present.
• polyester diols are also used which are obtained by reacting a lactone with a diol. They are characterized by the presence of a terminal hydroxyl group and a recurring polyester component of the formula - (- CO- (CHR) -CH 2 -0 -) -.
• n is preferably 4 to 6 and the substituent R is hydrogen, an alkyl, cycloalkyl or alkoxy radical.
• No substituent contains more than 12 carbon atoms. The total number of carbon atoms in the substituent does not exceed 12 per lactone ring. Examples include hydroxycaproic acid, hydroxybutyric acid, hydroxydecanoic acid and / or hydroxystearic acid.
• the lactone used as a raw material can be represented by the following general formula
• n and R de have the meaning already given.
• Unsubstituted -caprolactone in which n has the value 4 and all R substituents are hydrogen, is preferred for the preparation of the polyester diols.
• the reaction with lactone is started by low molecular weight polyols, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, dimethylolcyclohexane.
• low molecular weight polyols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, dimethylolcyclohexane.
• other reaction components such as ethylenediamine, alkyldiacanolamines or also urea, can also be reacted with caprolactone.
• polylactam diols which are prepared by reacting, for example, £ -caprolactam with low molecular weight diols.
• Aliphatic, cycloaliphatic and / or aromatic poly are used as typical multifunctional isocyanates isocyanates with at least two isocyanate groups per molecule.
• the isomers or isomer mixtures of organic diisocyanates are preferred.
• Suitable aromatic diisocyanates are phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, naphthylene diisocyanate and diphenylmethane diisocyanate.
• (cyclo) aliphatic diisocyanates Due to their good resistance to ultraviolet light, (cyclo) aliphatic diisocyanates produce products with a low tendency to yellowing. Examples include isophore diisocyanate, cyclopentylene diisocyanate and the hydrogenation products of aromatic diisocyanates, such as cyclohexylene diisocyanate, methylcyclohexylene diisocyanate and dicyclohexyl methane diisocyanate.
• aliphatic diisocyanates examples include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, dimethylethylene diisocyanate, methyltrimethylene diisocyanate and trimethylhexane diisocyanate.
• Isophorone diisocyanate and dicyclohexyl methane diisocyanate are particularly preferred as diisocyanates.
• the polyisocyanate component used to form the prepolymer can also contain a proportion of higher quality polyisocyanates, provided that this does not cause gel formation.
• Products which have been found to be useful as triisocyanates are those which result from the trimerization or oligomerization of diisocyanates or from the reaction of diisocyanates with compounds containing polyfunctional OH or NH groups. These include, for example, the biuret of hexamethylene diisooyanate and water, the isocyanurate of hexamethylene diisocyanate or the adduct of isophorone diisocyanate with trimethylolpropane.
• the average functionality can optionally be reduced by adding monoisocyanates. Examples of such chain-terminating monoisocyanates are phenyl isocyanate, cyclohexyl isocyanate and stearyl isocyanate.
• Polyurethanes are generally not compatible with water lent, unless special components are incorporated in their synthesis and / or special production steps are carried out. So large an acid number is built in that the neutralized product can be dispersed stably in water.
• compounds which contain two H-active groups reacting with isocyanate groups and at least one group capable of forming anions. Suitable groups which react with isocyanate groups are, in particular, hydroxyl groups and primary and / or secondary amino groups. Groups which are capable of forming anions are carboxyl, sulfonic acid and / or phosphonic acid groups. Carboxylic acid or carboxylate groups are preferably used.
• the isocyanate groups of the diisocyanate preferably react with the other groups of the molecule that are reactive toward isocyanate groups.
• alkanoic acids with two substituents on the carbon bm are used.
• the substituent can be a hydroxyl group, an alkyl group or an alkylol group.
• These polyols have at least one, generally 1 to 3 carboxyl groups in the molecule. They have two to about 25, preferably 3 to 10, carbon atoms. Examples of such compounds are dihydroxypropionic acid, dihydroxysuccinic acid and dihydroxybenzoic acid.
• R hydrogen or an alkyl group having up to about 20 carbon atoms.
• Examples of such compounds are 2,2-dimethylol acetic acid, 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid and 2,2-dimethylol pentanoic acid.
• the preferred dihydroxyalkanoic acid is 2,2-dimethylolpropionic acid.
• Compounds containing amino groups are, for example, -diaminovaleric acid, 3,4-diaminobenzoic acid, 2,4-diaminotoluenesulfonic acid and 2,4-diamino-diphenyl ether sulfonic acid.
• the polyol containing carboxyl groups can be 3 to Make up 100% by weight, preferably 5 to 50% by weight, of the total polyol component in the NCO prepolymer.
• the amount of ionizable carboxyl groups available as a result of the carboxyl group neutralization in salt form is generally at least 0.4% by weight, preferably at least 0.7% by weight, based on the solid.
• the upper limit is about 6% by weight.
• the amount of dihydroxyalkanoic acids in the unneutralized prepolymer gives an acid number of at least 5, preferably at least 10.
• the upper limit of the acid number is 70, preferably 40, based on the solids.
• this dihydroxyalkanoic acid is advantageously at least partially neutralized with a tertiary amine in order to avoid a reaction with the isocyanates.
• the NCO prepolymers used according to the invention can be prepared by simultaneously reacting the polyol or polyol mixture with an excess of diisocyanate.
• the implementation can also be carried out step by step in the prescribed order.
• reaction temperature is up to 150 ° C., a temperature in the range from 50 to 130 ° C. being preferred.
• the implementation continues until practically all hydroxyl functions have been implemented.
• the NCO prepolymer contains at least about 0.5% by weight of isocyanate groups, preferably at least 1% by weight of NCO, based on the solid.
• the upper limit is approximately 15% by weight, preferably 10% by weight, particularly preferably 5% by weight.
• the reaction can optionally be carried out in the presence of a catalyst, such as organotin compounds and / or tertiary amines.
• a catalyst such as organotin compounds and / or tertiary amines.
• the addition of orga is necessary niche solvents that do not contain active hydrogen according to Zerewitinoff possible.
• Usable solvents are, for example, dimethylformamide, esters, ethers, such as diethylene glycol dimethyl ether, keto esters, ketones, such as methyl ethyl ketone and acetone, ketones substituted with methoxy groups, such as methoxy hexanone, glycol ether esters, chlorinated hydrocarbons, aliphatic and alicyclic hydrocarbon pyrrolidones, such as N-methylpyrrolidone, hydrogenated furans, aromatic hydrocarbons and mixtures thereof.
• the amount of solvent can vary within wide limits and should be sufficient to form a prepolymer solution with a suitable viscosity.
• water-insoluble solvents boil lower than water, they can be gently distilled off after the production of the urea-containing polyurethane dispersion by vacuum distillation or thin-film evaporation.
• Higher-boiling solvents should be water-soluble and remain in the aqueous polyurethane dispersion in order to facilitate the confluence of the polymer particles during film formation.
• Particularly preferred solvents are N-methylpyrrolidone, optionally in a mixture with ketones, such as methyl ethyl ketone.
• the anionic groups of the NCO prepolymer are at least partially neutralized with a tertiary amine.
• the resulting increase in dispersibility in water is sufficient for infinite dilutability. It is also sufficient to consistently disperse the neutralized polyurethane containing urea groups.
• Suitable tertiary amines are, for example, trimethylamine, triethylamine, dimethylethylamine, diethylmethylamine, N-methylmorpholine.
• the NCO prepolymer is diluted with water and then results in a finely divided dispersion. Shortly thereafter, the isocyanate groups still present are added Di- and / or polyamines with primary and / or secondary amino groups implemented as chain extenders.
• the competitive reaction between amine and water with the isocyanate has to be well coordinated (time, temperature, concentration) in order to obtain optimal properties and well monitored for reproducible production.
• Water-soluble compounds are preferred as chain extenders because they increase the dispersibility of the polymeric end product in water. Hydrazine and organic diamines are preferred because they generally build up the highest molar mass without gelling the resin. However, the prerequisite for this is that the ratio of the amino groups to the isocyanate groups is selected appropriately.
• the amount of the chain extender is determined by its functionality, by the NCO content of the prepolymer and by the duration of the reaction.
• the ratio of the active hydrogen atoms in the chain extender to the NCO groups in the prepolymer should generally be less than 2: 1 and preferably in the range from 1.0: 1 to 1.75: 1.
• the presence of excess active hydrogen, especially in the form of primary amino groups, can result in polymers with undesirably low molecular weights.
• Polyamines are essentially alkylene polyamines having 1 to 40 carbon atoms, preferably about 2 to 15 carbon atoms. They can carry substituents that have no hydrogen atoms that are reactive with isocyanate groups. Examples are polyamines with a linear or branched aliphatic, cycloaliphatic or aromatic structure and at least two primary amino groups.
• the diamines include ethylenediamine, propylenediamine, 1,4-butylenediamine, piperazine, 1,4-cyclohexyldimethylamine, hexamethylenediamine-1,6, trimethylhexamethylenediamine, methanediamine, isophorondiamine, 4,4'-diaminodicyclohexylmethane and aminoethylethanolamine.
• Preferred diamines are alkyl or cyclo alkyl diamines, such as propylenediamine and l-amino-3-amino-methyl-3,5,5-trimethylcyclohexane.
• the chain can be extended at least partially with a polyamine that has at least three amine groups with a reactive hydrogen.
• This type of polyamine can be used in such an amount that unreacted amine nitrogen atoms with 1 or 2 reactive hydrogen atoms are present after the polymer has been lengthened.
• Such polyamines are diethylenetriamine, - • - * triethylenetetramine, dipropylenetriamine and dibutylene.
• Preferred polyamines are the alkyl or cycloalkyl triamines, such as diethylene triamine.
• small amounts of monoamines such as ethylhexylamine, can also be added.
• the mixture of emulsion polymer and polyurethane resin contained in the preferred aqueous base coating compositions as film-forming material consists of 95 to 40% by weight of emulsion polymer and 5 to 60% by weight of polyurethane resin, the proportions in each case relating to the solids
• the aqueous base coating compositions according to the invention advantageously also contain other compatible water-thinnable synthetic resins, such as e.g. Aminoplast resins, polyesters and polyethers, which generally serve as grinding resins for the pigments.
• other compatible water-thinnable synthetic resins such as e.g. Aminoplast resins, polyesters and polyethers, which generally serve as grinding resins for the pigments.
• the aqueous base coating compositions according to the invention preferably contain 5 to 20, particularly preferably 10 to 16% by weight, based on the total solids content of the base coating compositions, of a water-thinnable aminoplast resin, preferably melamine resin and 5 to 20, preferably 8 to 15% by weight. %, of a water-thinnable polyether (eg polypropylene glycol with a number average molecular weight of 400 to 900).
• a water-thinnable aminoplast resin preferably melamine resin and 5 to 20, preferably 8 to 15% by weight.
• a water-thinnable polyether eg polypropylene glycol with a number average molecular weight of 400 to 900.
• the pigments used in the base coating compositions according to the invention can be coloring pigments on an inorganic basis, such as e.g. Contain titanium dioxide, iron oxide, carbon black etc., coloring pigments on an organic basis as well as common metal pigments (e.g. commercially available aluminum bronzes, stainless steel bronzes ...) and non-metallic effect pigments (e.g. pearlescent or interference pigments).
• the base coating compositions according to the invention preferably contain metal pigments and / or effect pigments.
• the pigmentation level is in the usual ranges.
• crosslinked polymeric microparticles as disclosed in EP-A-38 127 and / or conventional rheological inorganic or organic additives, can be added to the base coating compositions according to the invention.
• water-soluble cellulose ethers such as hydroxyethyl cellulose, methyl cellulose or carboxymethyl cellulose
• synthetic polymers with ionic and / or associative groups such as polyvinyl alcohol, poly (meth) acrylamide, poly (meth) acrylic acid, act as thickeners.
• the base coating compositions according to the invention generally have a solids content of about 15 to 50% by weight.
• the solids content varies with the purpose of the coating compositions.
• metallic paints for example, it is preferably 17 to 25% by weight.
• plain-colored lacquers it is higher, for example 30 to 45% by weight.
• the coating compositions according to the invention can additionally contain customary organic solvents. Their share is kept as low as possible. For example, it is below 15% by weight.
• the basecoat compositions of the invention are generally adjusted to a pH between 6.5 and 9.0.
• the pH can be adjusted with conventional amines, e.g. Ammonia, triethylamine, dimethylaminoethanol and N-methylmorpholine can be adjusted.
• the task explained at the outset is solved.
• the base coating compositions according to the invention high-quality coatings can be produced without overpainting with a transparent top coating composition.
• the coating compositions according to the invention can be applied to any substrates, such as metal, wood, plastic or paper. The invention is explained in more detail in the following examples.
• Emulsion polymer dispersion 1 Emulsion polymer dispersion 1
• An emulsion is prepared in the stirrable feed vessel from 720 g of deionized water, 24 g of emulsifier 1, 10.8 g of acrylamide, 864 g of methyl methacrylate and 216 g of n-butyl methacrylate. 30% by weight of this emulsion are added for presentation. Then 28% by weight of a solution of 3.1 g of ammonium peroxodisulfate (APS) in 188 g of deionized water are added within 5 minutes. An exothermic reaction occurs. The reaction temperature is kept between 82 and 88 ° C.
• Emulsion polymer dispersion 2 Emulsion polymer dispersion 2
• emulsifier 1 submitted and heated to 80 ° C.
• An emulsion is prepared in the stirrable feed vessel from 720 g deionized water, 24 g emulsifier 1, 10.8 g acrylamide, 518 g methyl methacrylate, 292 g n-butyl methacrylate and 205 g styrene.
• An emulsion is prepared in the stirrable feed vessel from 748.2 g of deionized water, 20.3 g of emulsifier 1, 9.0 g of acrylamide, 718.1 g of methyl methacrylate and 179.5 g of n-butyl methacrylate. 30% by weight of this emulsion are added to the sample. Then 10% by weight of a solution of 7.2 g of ammonium peroxodisulfate in 305 g of deionized water are added dropwise within 5 minutes. An exothermic reaction occurs. The reaction temperature is kept between 82 and 88 ° C.
• reaction mixture is kept at 82 ° C. for 1.5 hours. It is then cooled and the dispersion is spread over a fabric 30 given around the mesh. A finely divided dispersion having a non-volatile content of 45% by weight, a pH of 2.5, an acid number of 14 and an OH number of 20 is obtained.
• thermometer In a cylindrical glass double wall vessel with stirrer, reflux condenser, stirrable inlet vessel, dropping funnel and thermo
• emulsifier 1 10.8 g of acrylamide, 864 g of methyl methacrylate and 216 g of n-butyl methacrylate. 30% by weight of this emulsion are added for presentation. Then 3.6 wt .-% of a solution of 8.6 g ammonium peroxodisulfate in 183 g deionized water within 5 minutes
• reaction temperature is kept between 82 and 88 ° C. 15 minutes after the addition of the ammonium peroxysulphate solution has ended, the remaining 70% by weight of the emulsion is mixed with the remaining 96.4% by weight of the ammonium peroxodisulphate solution.
• Emulsion polymer dispersion 5 Emulsion polymer dispersion 5
• reaction mixture is kept at 82 ° C. for 1.5 hours. It is then cooled and the dispersion is passed over a 30 ⁇ m mesh. A finely divided dispersion with a non-volatile content of 45% by weight, a pH of 5.8, an acid number of 13 and an OH number of 20 is obtained.
• the mass obtained is added to 1840 g of cold deionized water with vigorous stirring. With intensive stirring, 86 g of a 15% hydrazine solution are added to the dispersion obtained within 20 minutes. The resulting, very finely divided dispersion has a solids content of 35% and an expiry time of 27 seconds in the DIN cup 4.
• Mixtures 1 and 2 are prepared at 800-1000 rpm for 30 minutes to produce the basecoats of the invention. mixed and then adjusted to a pH of 7.7 with a 5% strength aqueous dimethylethanolamine solution. The viscosity is then adjusted to an outflow time of 25 seconds in a DIN 4 beaker by adding deionized water.
• the base coating compositions BB1, BB2, BB3 and BB4 according to the invention are obtained.
• the base coating composition BB5 is obtained by incorporating 36.2 g of the emulsion polymer dispersion 1 into the mixture 2. BB5 does not contain a polyurethane resin dispersion.
• the base coating compositions thus obtained show excellent storage stability.
• the base coating compositions are sprayed onto phosphated steel sheets (Bonder 132) coated with a commercially available electrocoat and a commercially available filler, after a flash-off time of 10 minutes, with a commercially available clearcoat and baked at 140 ° C. for 20 minutes.
• the metallic effect coatings obtained in this way show a good metallic effect, good adhesion to the filler, good adhesion between the basecoat and topcoat, good gloss and good resistance in a condensed water constant climate according to DIN 50 017.
• BB1, BB2, BB3 and BB4 show a better metallic effect than BB5.
• a part of the lacquered metal sheets is coated again with the base coating compositions BB1, BB2, BB3, BB4 and BB5 and overcoated with a commercially available clear lacquer.
• the coatings obtained in this way are baked at 80 ° C. for 40 minutes.
• the coatings baked at 80 ° C adhere excellently to the coatings baked at 140 ° C.
• a base coating composition produced using the emulsion polymer dispersion 5 as described above shows inadequate storage stability.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paints Or Removers (AREA)
• Polymerisation Methods In General (AREA)
• Graft Or Block Polymers (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6368825

Family Applications (1)

Country Status (9)

Cited By (3)

Families Citing this family (21)

Citations (5)

• 1988
  • 1988-12-09 DE DE3841540A patent/DE3841540A1/de not_active Withdrawn
• 1989
  • 1989-11-27 DE DE9090900099T patent/DE58905068D1/de not_active Expired - Fee Related
  • 1989-11-27 AU AU46550/89A patent/AU630645B2/en not_active Ceased
  • 1989-11-27 ZA ZA899023A patent/ZA899023B/xx unknown
  • 1989-11-27 WO PCT/EP1989/001434 patent/WO1990006186A1/de active IP Right Grant
  • 1989-11-27 JP JP2500544A patent/JPH075860B2/ja not_active Expired - Fee Related
  • 1989-11-27 EP EP90900099A patent/EP0447428B1/de not_active Expired - Lifetime
  • 1989-11-27 ES ES90900099T patent/ES2060136T3/es not_active Expired - Lifetime
  • 1989-11-27 BR BR898907816A patent/BR8907816A/pt not_active IP Right Cessation
  • 1989-12-08 CA CA002004988A patent/CA2004988C/en not_active Expired - Fee Related

Patent Citations (5)

Also Published As

Similar Documents

Legal Events