CA2135412A1 - Coating agents for transparent coating-lacquer layers, and use thereof in methods of producing multilayer coatings - Google Patents
Coating agents for transparent coating-lacquer layers, and use thereof in methods of producing multilayer coatingsInfo
- Publication number
- CA2135412A1 CA2135412A1 CA002135412A CA2135412A CA2135412A1 CA 2135412 A1 CA2135412 A1 CA 2135412A1 CA 002135412 A CA002135412 A CA 002135412A CA 2135412 A CA2135412 A CA 2135412A CA 2135412 A1 CA2135412 A1 CA 2135412A1
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- Canada
- Prior art keywords
- meth
- esters
- acrylic acid
- hydroxy
- acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
- C09D133/04—Homopolymers or copolymers of esters
- C09D133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09D133/062—Copolymers with monomers not covered by C09D133/06
- C09D133/066—Copolymers with monomers not covered by C09D133/06 containing -OH groups
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/4009—Two or more macromolecular compounds not provided for in one single group of groups C08G18/42 - C08G18/64
- C08G18/4063—Mixtures of compounds of group C08G18/62 with other macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
- C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
- C08G18/625—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids
- C08G18/6254—Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G18/00—Polymeric products of isocyanates or isothiocyanates
- C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
- C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
- C08G18/40—High-molecular-weight compounds
- C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
- C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
- C08G18/625—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids
- C08G18/6258—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids the acid groups being esterified with polyhydroxy compounds or epoxy compounds during or after polymerization
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Wood Science & Technology (AREA)
- Paints Or Removers (AREA)
- Application Of Or Painting With Fluid Materials (AREA)
Abstract
Herberts Gesellschaft mit beschrankter Haftung A B S T R A C T
The description relates to coating agents and use thereof in production of transparent top layers of multi-layer coatings.
The coating agents contain binders based on hydroxy-functional(meth)acrylic copolymers, blocked polyisocyanates, aminoplastic resins and, optionally, hydroxy-functional polyester resins together with conventional additives and solvents, and are characterised in that the binders contain:
A) 25 - 90 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from a1) 10 - 30 wt.% styrene and/or one or more styrene derivatives a2) 20 - 40 wt.% of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, a3) 5 - 15 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, a4) 1 - 15 wt.% of (meth)acrylic acid, a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, B) 0 - 40 wt.%, of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from b1) 5 - 20 wt.% styrene and/or one or more styrene derivatives, b2) 5 - 20 wt.% caprolactone, b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, of one or more hydroxy-functional polyesters, D) 5 - 35 wt.% of one or more blocked polyisocyanates and E) 5 - 30 wt. % of one or more aminoplastic resins, the sum of components a1) to a5), b1 to b5) and A to E) being 100 in each case.
The description relates to coating agents and use thereof in production of transparent top layers of multi-layer coatings.
The coating agents contain binders based on hydroxy-functional(meth)acrylic copolymers, blocked polyisocyanates, aminoplastic resins and, optionally, hydroxy-functional polyester resins together with conventional additives and solvents, and are characterised in that the binders contain:
A) 25 - 90 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from a1) 10 - 30 wt.% styrene and/or one or more styrene derivatives a2) 20 - 40 wt.% of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, a3) 5 - 15 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, a4) 1 - 15 wt.% of (meth)acrylic acid, a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, B) 0 - 40 wt.%, of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from b1) 5 - 20 wt.% styrene and/or one or more styrene derivatives, b2) 5 - 20 wt.% caprolactone, b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, of one or more hydroxy-functional polyesters, D) 5 - 35 wt.% of one or more blocked polyisocyanates and E) 5 - 30 wt. % of one or more aminoplastic resins, the sum of components a1) to a5), b1 to b5) and A to E) being 100 in each case.
Description
r~ ~ ~ 3~f~
Coatin~ aaents for transparent coatinq-lac~uer layers and use thereof in methods of producinq multilaver coatin~s The invention relates to coating agents for transparent stoving multilayer coatings for lacquering of mass-produced cars and characterised by high acid rain resistance and a high content of solids for processing.
JP patent publication number 1(1989)-158079 describes coating agents based on caprolactone-modified polyacrylate resins, optionally also containing hydroxyalkyl(meth~acrylates, alkylated melamine resins and optionally blocked polyisocyanates. These coating agents can be used to produce -high-solid car lacquer coats, but the level of acid rain resistance required in industry is not reached. The lacquers tend to turn yellow and have low initial gloss.
GB-A-2 254 328 and JP patent publication 5 025 431 describe ~ ~
coating agents comprising hydroxy-functional polyacrylate ~.s~ ~ `
resins and polyester resins, alkylated melamine resins and hexamethoxy methyl melamine resins, blocked acid catalysts and blocked polyisocyanates, which admittedly have high resistance i~
to acid but have a low content of solids for processing. ~-Also, these lacquers are not resistant to yellowing and their initial gloss is unsatisfactory.
JP patent publication number 4(1992)-246483 differs from GB-A-2 254 328 in that the coating composition additionally contains a catalyst in the form of organotin compounds.
DE-A-42 04 518 describes non-aqueous transparent coating lacquers based on hydroxyl group-containing synthetic resins, - -aminoplastic resins and blocked polyisocyanates, the latter being blocked with dialkyl malonates or with oximes or blocking agents containing methylene groups. As before, the - '~1 3~3~:~.2 acid resistance of the resulting lacquer coats is not completely satisfactory. ;
The aim of the invention is to provide coating agents for multi-layer stoving coatings, the agents being suitable for lacquering of mass-produced cars and also having a high content of solids for processing and improved resistance to acid rain, which is shown analytically by high resistance to sulphuric acid. ~-~
It has been found that the requirement for coating agents resistant to sulphuric acid and also with a high solid content can be met by means of coating agents containing one or more hydroxy-functional (meth)acrylic copolymers in addition to blocked polyisocyanates, aminoplastic resins, conventional lacquer additives and solvents, and optionally one or more ~ -hydroxy-functional polyesters.
! . . ~
The invention therefore relates to the aforementioned coating ~ -agents, in which the binders contain~
A) 25 - 90 wt.~ of one or more hydroxy-functional I (meth)acrylic copolymers, obtainable from - ~ -¦ al) 10 - 30 wt.~ styrene and/or one or more styrene derivatives a2) 20 - 40 wt.~ of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, . . .
a3) 5 - 15 wt.~ of one or more hydroxyalkyl esters of (meth)acrylic acid, -. ;.' a4) 1 - 15 wt.~ of (meth)acrylic acid, ;'~
. ' . ;, 2 1 3 '~
a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, '.'~ :'', ) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from bl) 5 - 20 wt.~ styrene and/or one or more styrene ~;
derivatives, ., . .,, ~ , . .
b2) 5 - 20 wt.~ caprolactone, i~ -b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, -~
b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or more hydroxy-functional polyesters, D) 5 - 35 wt.~ of one or more blocked polyisocyanates and ;
E) 5 - 30 wt.% of one or more aminoplastic resins, the sum of components al) to a5), bl to b5) and A to E) being 100 in each case.
The (meth)acrylic copolymers in the coating agents according to the inventio~ can be manufactured by radical copolymerisation by conventional methods. The solution polymerisation method is preferred for synthesis of the (meth)acrylic copolymers (components A and B) used in the coating agents according to the invention. In this method the solvent is placed in the reaction vessel, heated to boiling~
..
., .~.
~ 1 3 S '~
point, and the mixture of monomers and initiators is added ~-continuously during a predetermined time.
The term "(meth)acrylic" used in the present description and claims is synonymous for "acrylic and/or methacrylic".
Polymerisation is brought about e.g. at temperatures between 80C and 160C, preferably 100C to 150C.
r-The polymerisation reaction can be started with known polymerisation initiators, e.g. per- or azo-compounds which thermally decompose into radicals in a first-order reaction.
The nature and amount of initiator are chosen so that a substantially constant supply of radicals is available at the polymerisation temperature during the intake phase. `-The following are examples of initiators preferably used for polymerisation: dialkyl peroxides such as di-tert.-butyl peroxide, di-cumyl peroxide; diacyl peroxides such as di-benzoyl peroxide, di-lauroyl peroxide; hydroperoxides such as cumene hydroperoxide, tert. butyl hydroperoxide; peresters such as tert. butyl perbenzoate, tert. butyl perpivalate, ~ ~
tert. butyl-per-3,5,5-trimethyl hexanoate, tert. butyl-per-2- ~ `;
ethyl hexanoate; peroxydicarbonates such as di-2-ethyl hexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate; perketals such as 1,1-bis-(tert. butylperoxy)-3,5,5-trimethyl -cyclohexane, 1,1-bis- (tert.butylperoxy)cyclohexanei ketone ~ -peroxides such as cyclohexanone peroxide or methyl isobutyl ketone peroxidei azo compounds such as 2,2~-azo-bis(2,4-dimethyl valeronitrile), 2,2'-azo-bis-(2-methyl butyronitrile), 1,1'-azo-bis-cyclohexane carbonitrile or azo-bis-isobu~yronitrile. `~
Preferably the polymerisation initiators, more particularly the peresters, are added in a proportion of 0.2 to 5 wt.~ of the weighed-in quantity of monomers.
-` 21 3 ~ ~ ~ 2 The organic solvents advantageously used in solution ~.
polymerisation are conventional lacquer solvents, such as can also be used later ln the coating agents according to the invention, e.g. glycol ethers such as ethylene glycol dimethyl ether; glycol ether esters such as ethyl glycol acetate, butyl glycol acetate, 3-methoxy-n-butyl acetate, butyl diglycol acetate, methoxypropyl acetate, esters such as butyl acetate, ---isobutyl acetate, amyl acetate; or ketones such as methyl `- -~
ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone or isophorone. Alcohols such as methanol, ethanol, propanol, butanol, aromatic hydrocarbons such as ~`
xylene, Solvesso 100 (registered trade mark for a mixture of aromatic hydrocarbons with a boiling range of 155 to 185C) ~ :
and aliphatic hydrocarbons can also be used, blended with the aforementioned solvents.
In order to adjust the molecular weight, particularly in the .
preferred solution polymerisation, use can be made of chain transfer agents such as mercaptans, thioglycolic acid esters, chlorinated hydrocarbons, cumene or dimeric alpha-methyl styrene. ~ .
The polymerisation conditions (reaction temperature, intake time of the monomer mixture, concentration of solvent) are adjusted so that the (meth)acrylic copolymers for the coating agents produced according to the invention have a weight ~ :~
average molecular weight (determined by gel permeation chromatography using polystyrene as a calibrating substance) of 2500 - 10000.
~ ' :
The hydroxyl group-containing (meth)acrylic copolymers in the :
coating agents produced according to the invention are preferably situated in a glass transition temperature range of -20C to +40C, calculated from the glass transition temperature of the homopolymers of the individual monomers as given in the literature (Fox equation, see e.g. Polymere Werkstoffe, Batzer, 1985, page 307). .
:' ~
. ' :~-1 3 ~ 2 The monomers for producing the hydroxy-functional(meth)acrylic copolymers (component A) and used as component a2) are e.g.
glycidyl and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids (e.g. the -~ ;
commercial products CARDURA E10 and VEOVA 10 produced by Shell AG). The other monomers for producing (meth)acrylic copolymers (components A and B) are e.g. styrene and/or styrene derivatives, such as vinyl toluene, p-methyl styrene or p-tert. butyl styrene, hydroxyalkyl esters of acrylic acid `~
or methacrylic acid such as beta-hydroxy-ethyl acrylate, beta-hydroxyethyl methacrylate, beta-hydroxypropyl acrylate, beta- ~ -hydroxypropyl methacrylate, butanediol-1,4- monoacrylate, butanediol-1,4-monomethacrylate, hexanediol-1,6-monoacrylate or hexanediol-1,6-monomethacrylate. Alternatively, at least partial use can be made of polyalkylene oxide -mono(meth)acrylates with 2 to 10 alkylene oxide units per molecule, or alkyl esters of acrylic acid or methacrylic acid; -methacrylates, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl methacrylate, tert. butyl acrylate, ~ ~
n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, ; ~ -isobutyl methacrylate, cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, 2-ethyl hexyl acrylate, 2-ethyl hexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, isobornyl acrylate or isobornyl methacrylate.
In order to provide the (meth)acrylic copolymers A) and B) with carboxyl groups, (meth)acrylic acid is incorporated by polymerisation, preferably in quantities such that the resulting acid number is 1 to 30 mg KOH/g. In order to introduce hydroxyl groups into the (meth)acrylic copolymers A) and B), hydroxyalkyl esters of (meth)acrylic acid (a3 to b3) are used preferably in quantities such that the resulting hydroxyl numbers are 40 to 200 mg KOH/g. ;~
The polyesters optionally used as component C) are polycondensation products of polyvalent polycarboxylic acids ~-2 1 3 ~ ~ 1 2 (e.g. dicarboxylic acids) or anhydrides thereof or polyhydric polyols, optionally also using monocarboxylic acids. These polymers are usually prepared with an excess of alcohol. The OH numbers are e.g. about 30 to 200, preferably 60 to 160 mg ~ - -KOH/g. The acid numbers are e.g. 1 to 50, preferably 5 to 30. --The weight average molecular weight is e.g. 500 to 4000, i~
preferably 1000 to 2000 g/mol. The following are examples of suitable polycarboxylic acids: o-phthalic acid (anhydride) isophthalic acid, terephthalic acid, tetrahydrophthalic acid (anhydride), 1,2-cyclohexane dicarboxylic acid (anhydride), 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, 4-methyl hexahydrophthalic acid (anhydride), endomethylene tetrahydrophthalic acid (anhydride), trimellitic acid (anhydride), succinic acid (anhydride), glutaric acid, adipic acid, azelaic acid, sebacic acid, butane tetracarboxylic acid or dimeric fatty acid.
The polyesters can also contain small proportions of condensed `~
maleic acid anhydride. Optionally the aforementioned polycarboxylic acids can be used together with natural or synthetic monocarboxylic acids such as benzoic acid, tert.
butyl benzoic acid, lauric acid, isononanoic acid or fatty acids from naturally-occurring oils.
The following are examples of suitable alcohol components for preparing the polyesters: diols such as ethylene glycol, ;~
diethylene glycol, triethylene glycol, polyethylene glycols, propanediols, polypropylene glycols, butanediols, hexanediols, neopentyl glycol, cyclohexane diol, cyclohexane dimethanol, trimethyl pentane diol, ethyl butyl propane diol, or polyvalent alcohols such as trimethylol ethane, trimethylol propane, di-trimethylol propane, glycerol, pentaerythritol, ;~
di-pentaerythritol or tris-hydroxyethyl isocyanurate. -The polyesters can contain a modification component in the form of glycidyl esters of alpha, alpha~-di-substituted -~
monocarboxylic acids and epsilon caprolactone.
:,'. ~...`-Component D) in the coating agents according to the invention comprises blocked aliphatic or cyclo-aliphatic polyisocyanates in conventional use in the lacquer sector, e.g. diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate or 1,3- dimethyl-cyclohexyl-1,3-diisocyanate. Other examples of aliphatic or cycloaliphatic polyisocyanates are biuret group- ~ -containing products of a reaction between 3 mols of hexamethylene diisocyanate and one mol of water, with an NCO ;
content of about 22%; isocyanurate group-containing poly-isocyanates prepared by trimerisation of 3 mols of diisocyanate, e.g. hexamethylene diisocyanate or isophorone diisocyanate trimers, or urethane group-containing poly-isocyanates, obtained by a reaction between 3 mols of diisocyanate and 1 mol of triol. Isophorone diisocyanate trimers are preferably used.
The blocking agents can be conventional CH acids, NH- or OH-functional compounds, which bring about cross-linking under the hardening conditions, e.g. CH-acid esters such as aceto-acetic alkyl esters, malonic acid dialkyl esters, epsilon caprolactam, alcohols such as tert. butanol or oximes such as methyl ethyl ketoxime. Malonic acid dialkyl esters and oximes are preferred. It may be advantageous simultaneously to use various masking agents, either inside a polyisocyanate molecule or in a mixture.
It has been found that the coating agents of the invention provide particularly light and essentially yellowing-free coatings, if blocked ~ h polyisocyanates are used as component û) which are prepared by reaction of `:~ ~ .
free isocyanates under water-free conditions with blocking agents containing ;~
acid hydrogen, in the presence of basic catalysts, wherPin one or more alkali hydroxides are used as .basic catalysts. The thus obtained blocked ~ `:-polyisocyanates.have a particularly low alkali content due to the use of :-:
:: .....
: ~;:
:
-" 21~ 112 g ~ ., . . ~ ~. .
basic catalysts. Said content is preferably less than 100 ppm, particularly preferably less than 80 ppm and less than 50 ppm, calculated ad the weight of the alkali metals and based on the weight of the blocked isocyanates. `
.,:: ~ ~;.
The above mentioned process can be applied to any isocyanates with free isocyanate functions. It is, e.g. possible to use the above mentioned polyisocyanates.
.:
Know blocking agents containing acid hydrogen may be used for the above mentioned preparation of the polyisocyanates, e.gO the blocking agents examplified above. Specific examples are dialkyl malonic esters and alkyl acetoacetic esters. The alkyl groups of the esters, which in the dialkyl malonic ester may be the same or different, have preferably 1 to 4 carbon atoms.
When preparing the polyisocyanates as explained above, the molar ratio of the blocking agents containing acid hydrogen to the NCO groups of the isocyanates, for example, ~ .
the ratio of the dialkyl malonic esters and/or alkyl acetoacetic esters to NCO groups may range, for example, from 0.5:1 to 1:1.5. In the case of an NCO excess, the free NCO groups may optionally be reacted with other reactants. ~ ~-The catalysts used for the above explained process are alkali hydroxides, for example, alkali metal hydroxides such as lithium, sodium and/or potassium hydroxide. The water-free alkali metal hydroxides are used in preference. Lithium hydroxide is used in particular preference. The catalysts are used in catalytic .
quantities, for example, in quantities o, 0.1 to 2~ by wt., ~ -~
preferably 0.3 to 1~ by wt., based on the weight or isocyanate and blocking agent.
", 2 ~ 3, '' 1 2 , ~
.
The catalysts are used in solid form, for exam?le, in the form of a powde~
The addition of the blocking agent to the isocyanat- is ~-ca-ried out under wate--free conditions, pref~rably wlth the careful e:cclusion of moisture. The ~_~ctlon may be ca-ried out, for example, under a dry i.e-. cas, such as nitrogen. -The reaction may take place without solvents or in the presence of organic solvents. Suitable solvents a-=, in particular, those that do not react with polyisocya~at-s.
Examples of such solvents are orcanic solvents, suc:~ as ali?hatic and aromatic hydrocarbor.s, for ecample, x~lene, mix.ures of aliphatic and/or aromatic hvc-oca-bons, es.e~s and ethers.
In the process described above it is possible, after the reaction has ended, to remove easily the catalyst that remains undissolved in the reaction medium. This may be carried out, for example, by filtering or centrifuging.
optionally, the reaction product may be diluted beforehand or afterwards with solvents. In this case, solvents that can react with free polyisocyanates may also be used.
Suitable solvents are organic solvents, particularly solvents customary in lacquers, such as aromatic hydrocarbons, for example, xylene, aliphatic hydrocarbons, for example, n-hexane or cyclohexane, mixtures of aliphatic and/or aromatic hydrocarbons, ketones such as, for example, acetone, methylisopropyl ketone, esters such as, for example, butyl acetate or ethyl acetate, ethers such as, for example, methoxypropanol or butoxypropanol. ~lcohols, such as, for example, isopropanol or hexanol, may, however, also be used.
. - . ....................................... .
. .: ~ . . .
2 ~ 3 ~ ~ 1 2 The coating agents used according to the invention contain cross-linking agents such as aminoplastic resins (component E). The aminoplastic resins used can be conventional cross~
linking agents in the lacquer sector. Suitable aminoplastic resins include e.g. alkylated condensates obtained by reaction `~
o~ amino triazines and amido triazines with aldehydes. They are manu~actured by known methods by condensing amino or amido-group containing compounds such as melamine, benzoguanamine, dicyanodiamide, urea or N,N-ethylene urea in the presence of alcohols such as methyl, ethyl, propyl, isobutyl, n-butyl or hexyl alcohol with aldehydes, ~'~ .::~ ' ' , ; ~., , ,:i .i ~: . -.,. ~ ii.~, .
' ';.~-' .',-' ., "
, ., . ~ ",, j, . ~ ., .
.," ~ .~,"
~ . -: :~ ..
,',' '"''.-.- -,.~
~ ..
.. , ~ -:: :
12 2~ ~5 ~2 particularly formaldehyde. The reactivity of these amine resins is determined by the degree of condensation, the ratio of the amine or amide component to the formaldehyde and the nature of the etherification alcohol used.
The coating agents containing the binders for use according to the invention can contain the aforementioned solvents together with conventional lacquer adjuvants such as levelling agents, e.g. based on (meth)acrylic homopolymers, silicone oils, plasticisers such as phosphoric acid, phthalic acid or citric -acid esters, substances for influencing the flow properties, such as pyrogenic silicone oxide, microgels, urea group- -containing products obtained by a reaction between primary ~f amines and polyisocyanates, hydrogenated castor oil, curing ;~
accelerators for reacting the hydroxyfunctional binders according to the invention (components A, B and C) with blocked isocyanates (component D) and aminoplastic resins (component E); phosphoric acid, phosphoric acid esters, dicarboxylic acid semiesters, citric acidi organic metal salts such as dibutyl tin dilaurate, zinc naphthenate, bismuth tricarboxylate, or tertiary amino group-containing compounds such as triethylamine and light-excluding agents.
The coating agents according to the invention are particularly `
suitable for producing a transparent top layer during the manufacture of stoving multi-layer coatings. The top layer can be applied by the wet-on-wet method, when both layers are hardened simultaneously. The invention therefore also relates to the method of producing multi-layer coatings or using the coating agents for manufacturing them. The solvent-containing coatings according to the invention can be applied in the form of a transparent top lacquer on layers of aqueous or solvent-containing base lacquers for hardenable multi-layer coatings. ;
The coating agents according to the invention are applied by ~ ~
known methods such as spraying, immiersion, rolling or doctor ~`
blade. The top-lacquer layer is applied to the substrate, ~
-~` 21~5`~2 -:
which is optionally already covered with other lacquer layers. ~ ;
The coating agents according to the invention can also be applied by spraying, using supercritical carbon dioxide as a ~ ~-solvent. The content of organic solvents can be greatly reduced. After an evaporation phase, the applied coating agent is cross-linked, preferably by heating. The stoving temperatures are usually between 110 and 160C, preferably between 120 and 150C. The thickness of the stoved film is about 15 - 50 ~m. The result is a cross-linked, hard, glossy lacquer coating. One preferred embodiment is use o~ the coating agent according to the invention as a clear lacquer coating on a base lacquer. Operation can be wet-on-wet, or alternatively the base lacquer is previously dried by heating.
This results in particularly good adhesion between the two layers.
Coating agents formulated as clear lacquers according to the invention can be applied e.g. over base lacquers, which can contain conventional coating-lacquer pigments, preferably decorative pigments such as metallic pigments. The binder bases of the base lacquer preferably comprises polyester, polyurethane or acrylate resins. These binders can optionally be cross-linked by cross-linking agents, e.g. melamine or isocyanate derivatives.
The coating agents according to the invention are particularly suitable for top lacquers or clear lacquers, preferably for use in the motor-vehicle sector but also in other areas. The use of the coating agent according to the invention for multi~
layer lacquering is particularly suitable for lacquering mass-produced motor vehicles, but uses are also possible for other purposes, such as domestic appliances or for the furniture industry.
The coating agents according to the invention are particularly suitable for manufacturing a transparent top layer of a ~ ;
~ ~ 3 ~
stoving multi-layer coating. They are particularly suitable for lacquering of mass-produced car bodies and parts thereof.
The coating agents according to the invention can be applied -wet-on-wet on conventional, i.e. solvent-containing or aqueous, lacquer layers, when both layers are simultaneously hardened at elevated temperature. For example, transparent top layers applied to the clear lacquers according to the invention can be applied by the wet-on-wet process on conventional or aqueous base lacquers. The two layers can then be hardened simultaneously. The hardening temperatures are e.g. of the order of 120 to 150C. The hardening times are e.g. of the order of 20 to 40 minutes.
Accordingly the invention also relates to manufacture of multi-layer coatings or use of the coating agents according to the invention for producing top lacquer layers, e.g. clear -~ -lacquer layers, for hardenable multi-layer coatings. ~ ;
The following examples illustrate the invention. A11 parts are by weight.
Manufacture of the (meth)acrylic copolymers : :
Example of manufacture AC-1 173 g of SOL~ESSO 150 (product sold by Shell AG) and 5 g of ~ 0 n-butanol were placed in a 2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and were heated to 152C with agitation, after switching on the reflux condenser. During -six hours, a mixture of 67 g acrylic acid, 160 g styrene, 150 g butyl acrylate, 65 g 2-hydroxyethyl acrylate, 220 g CARDURA E10 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 22 g tert. butyl. peroctoate were continuously added. Next, the batch was additionally polymerised at 150C
:: ~
. . ; ~ ''`~`
2l3~2 for 4 hours, cooled to 80C and diluted with 62 g Solvesso 100 and 62 g n-butanol. ~ .
Example of manufacture AC-2 163 g SOLVESSO 150 (product sold by Shell AG), 5 g n-butanol ~ ~ -and 70 g VEOVA 10 (product sold by Shell AG) were placed in a - -~
2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and were heated to 152C with agitation, using a reflux condenser. A mixture of 47 g acrylic acid, 160 g styrene, 125 g butyl methacrylate, 110 g 2-hydroxyethyl methacrylate, 150 g CARDURA E10 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 22 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 152C for 5 hours, cooled to 80C
and diluted with 72 g Solvesso 100 and 60 g n-butanol.
Example of ma~ufacture AC-3 232 g SOLVESSO 100 (product sold by Shell AG) was placed in a 2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and heated to 148C with agitation, after switching on the reflux condenser. A mixture of 14 g acrylic acid, 65 g styrene, 224 g butyl methacrylate, 141 g 2-hydroxypropyl methacrylate, 45 g 2-hydroxyethyl acrylate, 52 g lauryl acrylate, 89 g caprolactone, 4 g di-tert. butyl peroxide and 16 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 148C
for 5 hours, cooled to 80C and diluted with 46 g Solvesso 100 and 72 g n-butanol.
Example o~ ma~u~acture AC-4 185 g of SOLVESSO 100 (product sold by Shell AG) and 5 g butanol were placed in a 2-litre 3-necked ground-glass flask .. . :. .
16 213 ~ '1 12 equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and heated to 152C with agitation, after switching on the reflux condenser. A mixture of 67 g acrylic acid, 160 g styrene, 84 g butyl acrylate, 87 g 2-hydroxyethyl acrylate, 220 g CARDURA E10 (product sold by Shell AG), 16 SOLVESSO 100 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 16 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 148C for 5 hours, cooled to 80C
and diluted with 79 g SOLVESSO 100 and 65 g n-butanol. -~
~r ~ ~ ~
Example of manufacture PE~
170.3 g hexanediol-1,6 and 128.9 g trimethylol propane was placed and melted in a 2-litre 3-necked flask equipped with a thermometer, agitator and condenser. Next, 0.3 g of ~`
hypophosphorous acid, 37 g xylene, 228.2 g hexahydrophthalic acid anhydride and 278.6 g dimeric fatty acid was poured in with agitation, heating and under a stream of inert gas, and heated to 220C at the rate of 20C per hour. After an acid number of 22 had been reached, the mixture was cooled to 100C
and diluted with 156 g Solvesso 100 (product sold by Shell ~;
AG).
. ~:
Exam~le 1 Manufacture of a clear lacouer , ~, A single-component clear lacquer was manufactured by homogeneous mixing of 24.4 parts of the resin solution in Example AC-3 with 28 parts of the resin solution in Example AC-1, 10.75 parts Solvesso 100, 7.5 parts of a 70% butyl glycolic solution of the isocyanurate of isophorone diisocyanurate blocked with butanone oxime, 3 parts butanol, 16.6 parts of a commercial 58% solution of a highly reactive butanol-etherified melamine resin in butanol/xylene, 3.2 parts ~ ~
of butyl glycol acetate, 1.2 parts of a 1 : 1 mixture of ~;
' ' ' ~ ' ':
.,,, ~-.~ -17 ~ 2 commercial light-excluding agents based on benzotriazole and HALS, 1 part of silicone oil, 0.35 parts o~ dibutyl tin ~ :.
dilaurate and 4 parts of butyl diglycol. -~
Exam~le 2 Manufacture ~f a clear lacouer In the same manner as in Example 1, a single-component clear lacquer was produced from 31.6 parts of the resin solution in Example AC-1, 13.8 parts of the resin solution in Example PE-1, 20.2 parts of a commercial 70~ butanolic solution of a melamine resin co-etherified with methanol and butanol, 11.7 parts of a solution of the blocked polyisocyanate from clear- :~
lacquer example 1, 11.24 parts of Solvesso 100, 1.2 parts of the light-excluding agent mixture in clear-lacquer example 1, 0.8 parts butanol, 3.3 parts butyl glycol acetate, 1 part of `~
silicone oil, 0.76 parts of dibutyl tin dilaurate and 4.4 - -~
parts of butyl diglycol.
Example 3 Manufacture of a clear lacouer In the same manner as in Example 1, a single-component clear lacquer was produced from 46.2 parts of the resin solution in ;~
example AC-4, 13.5 parts Solvesso 100, 7.1 parts of a commercial 70~ butanolic solution of a melamine resin co- ~.;
etherified with methanol and butanol, 2'.4 parts of a 70 Solvesso 100 solution of an isocyanurate of isophorone diisocyanate blocked with malonic acid:diethyl ester, .
1.2 parts of the light-excluding agent mixture in clear-lacquer example 1, 0.84 parts of butanol, 3.5 parts of butyl glycol acetate, 1 part of silicone oil, 0.76 parts of dibutyl tin dilaurate and 4.5 parts of butyl diglycol.
` ` !
''; ~''' 18 2t3~2 Sheet-metal bodies previously coated with commercial cathodically depositable electrodeposition lacquers (KTL) conventionally used for lacquering mass-produced cars (KTL;
18 ~m) and commercial fillers (35 ~m) were lacquered with commercial water-dilutable metallic-based lacquer in a dry .
layer thickness of 15 ~m and pre-dried at 80C for 6 minutes.
Directly afterwards, the clear lacquer in clear-lacquer examples 1, 2 and 3 was applied by spraying wet-on-wet in a dry layer thickness of 35 ~m and stoved at 140C (the object temperature) for 20 minutes after 5 minutes' ventilation at room temperature.
Corresponding comparative experiments were made with prior-art lacquers. The results are given in the following Table. The tests were carried out in accordance with general industrial standards. The clear lacquers were tested for resistance to sulphuric acid by the drop test, using 10% and 38% H2SO4 ~- -respectively. The metal test sheets were placed on a heatable plate and heated to 65C. Care was taken that the sheets rested flat, to ensure optimum transmission of temperature. ~;~
At the end of the heating-up phase, i.e. at 65C, one drop per minute was applied to the clear-lacquer surface. The total time was 30 minutes. At the end of the test time, the lacquer was washed off with water. When necessary, a brush could additionally be used for cleaning.
In order to judge the resistance to sulphuric acid, the period of action, in minutes, is given at which the first visible ;~
change in the film (swelling) damage (dulling) or corrosion of base lacquer occurs.
, ., :, ''.'.'.'.
',. '~;",' .' '' ~ ~ 3 ~ l~ '1 2 : , . ~ .
Table Clear lacquers according to the invention~
ExamDle: 1 2 3 .'''~'~',',7 '' Yellowing: _ None_ Slight None _ " -Content of solids for ~rocessing (%) 47.1 51.2 48.1 20qloss 84 _ 88 88 Pendulum hardness~
(Number of vibrations) 75 77 84 ~-.
Sulphuric acid test 10% H2S04, 30'60C
Swelling 13 17 14 Dulling 21 22 30 Corrosion of base coat 24 30 ~30 Sulphuric acid test :~
, 0 0 ~ ~ 0 ~
~ O A2 C~ V4, ~ u ~, v Swelling 20 11 13 Dulling ,30 ~30 28 Corrosion of base coat 28 30 >30 ,~
Pencil hardness: HB HB HB
;" .~ ','`;~''' Clear lacquers used for comparison JP-A GB-A JP-A DE-A
. " ~
246483 2254328 158079 4204518 : ~;
Example 2 4 1 7 Yellowing: Sliaht Strong Stronq None Contents of.
solids for processinq (%) 32.4 41.5 58.1 50.8 20gloss 83 58 29 82 :. ~ ..: . :~.: .......
" ,, .. ;.-.-., .~
.. , ,: . . ~, : .. . ..: .
2 ~ 3 ;~
Pendulum hardness (number of vibrations) 84 85 38 82 ~ ~ ~
Sulphuric acid ~ ~-test 10~ H2SO4, 30'60C
Swelling 14 12 10 10 Dulling ~30 ,30 13 13 Corrosion of base coat 22 18 19 19 Sulphuric acid test ;~
39~ H2SO4, 30'60C
Swelling 9 2 2 5 Dulling ~30 11 11 11 Corrosion of base coat 25 15 15 13 -Pencil hardness HB F 2B HB _ ~ ' As the preceding Table shows, the coating agents according to the invention, as compared with JP-A-246 483, are characterised particularly by an improved solids content and improved resistance to acid at elevated temperatures. As compared with GB-A-2 254 328 the coating agents according to the invention likewise have an improved solids content, with improved gloss and improved resistance to acid. According to the invention, the gloss, pendulum hardness and resistance to acid are also improved compared with JP-A-158 079. By comparison with DE-A-42 04 518 the invention provides considerably improved resistance to acid. -"';';'` '~ ',.''''',.
:;~;' ,, '-.' . . ~,:
.. .. .~.. -2 1 3 ~
.~
Example of manufacture Pl~
,: ~
Reaction of isophorone diisocyanate-isocyanurate with diethyl malonate :.. - ~, ,~,:
376 (P = parts by weight) of isophorone diisocyanate-isocyanurate : ~
(obtainable from Huls under the trade name ~estanat IPDI T-1890) are -. .
dissolved in 350 P of Solvesso lO0 with heating to 80 C.
Subsequently, 4 P of water-free lithium hydroxide are added. Then 271 P of diethyl malonate are added dropwise in such a way that the reaction temperature does not exceed 90 C. The reaction mixture is kept at 90 C until an NCO
content of c0.5~ is reached. The undissolved lithium hydroxide is filtered by filtration ove- G 1 ~m filter.
. .. ~
Final values: solids (1 h/150 C): 60 /, visccsi-y ~ ~
(25 C): 2400 mPas, colour number (C-a-~-.e-): 2; l thium'~'''''i~,~,f content (atomic absorption spectroscopy): ~8 p_m ~ ~
~- :. ,-, :.
Example of manufacture Pl-2 Reaction of hexamethylene diisocyanate-isocyanurate wlth diethyl malonate -~
In the same way as e~cample 1), 351 ~ of ~e:camethylen~
diisocyanate-isocyanurate (obtainaDl- f-_~ R~.c-.--~^ulenc under the trade name Tolonat HDT/100) G-e _eac~ed wi.h ... ,.., ~ ~ .
' '~ ',~
- .. . ~...
... ~ .. ..;
,. ,. ~ . . :.
``````` '`.~
,": ~
1 3~ 2 ~2 :~
~ ~ ''~.','.`
295 P of diethyl malonate in 350 P of Solvesso 100 in the :
presence of .3 P of water-free lithium hydroxide. ~-~
Final values: solids (1 h/150 C): 60.3~; viscosity ; ~,' !~' (25 C): 680 mPas; colour number (Gardner): 1. '1'i~''"'''.,"~
Example of manufacture P1-3 Reaction of isophorone diisocyanate-isocyanurate with ethyl ~ a 10 acetoacetate In the same way as exam~le 1), alo P of Vestanat I~DI ;;~
T-1890 are reacted with 240 P of ethyl acetcacetat~ ir.
350 P of Solvesso 100 in the presence of ~.1 F of wate~
15 free lithium hydroxide. "~
Final values: solids (1 h/150 C): 61~; vis~~sitv (25 C): 1300 mDas; colcur numbe_ (G~rc-~
If the polyisocyanates of Example of manufacture Pl-1, Pl-2 and Pl-3 are used as component D), the obtained coatings are particularly .. `
free of yellowings. :
`~ ~
Coatin~ aaents for transparent coatinq-lac~uer layers and use thereof in methods of producinq multilaver coatin~s The invention relates to coating agents for transparent stoving multilayer coatings for lacquering of mass-produced cars and characterised by high acid rain resistance and a high content of solids for processing.
JP patent publication number 1(1989)-158079 describes coating agents based on caprolactone-modified polyacrylate resins, optionally also containing hydroxyalkyl(meth~acrylates, alkylated melamine resins and optionally blocked polyisocyanates. These coating agents can be used to produce -high-solid car lacquer coats, but the level of acid rain resistance required in industry is not reached. The lacquers tend to turn yellow and have low initial gloss.
GB-A-2 254 328 and JP patent publication 5 025 431 describe ~ ~
coating agents comprising hydroxy-functional polyacrylate ~.s~ ~ `
resins and polyester resins, alkylated melamine resins and hexamethoxy methyl melamine resins, blocked acid catalysts and blocked polyisocyanates, which admittedly have high resistance i~
to acid but have a low content of solids for processing. ~-Also, these lacquers are not resistant to yellowing and their initial gloss is unsatisfactory.
JP patent publication number 4(1992)-246483 differs from GB-A-2 254 328 in that the coating composition additionally contains a catalyst in the form of organotin compounds.
DE-A-42 04 518 describes non-aqueous transparent coating lacquers based on hydroxyl group-containing synthetic resins, - -aminoplastic resins and blocked polyisocyanates, the latter being blocked with dialkyl malonates or with oximes or blocking agents containing methylene groups. As before, the - '~1 3~3~:~.2 acid resistance of the resulting lacquer coats is not completely satisfactory. ;
The aim of the invention is to provide coating agents for multi-layer stoving coatings, the agents being suitable for lacquering of mass-produced cars and also having a high content of solids for processing and improved resistance to acid rain, which is shown analytically by high resistance to sulphuric acid. ~-~
It has been found that the requirement for coating agents resistant to sulphuric acid and also with a high solid content can be met by means of coating agents containing one or more hydroxy-functional (meth)acrylic copolymers in addition to blocked polyisocyanates, aminoplastic resins, conventional lacquer additives and solvents, and optionally one or more ~ -hydroxy-functional polyesters.
! . . ~
The invention therefore relates to the aforementioned coating ~ -agents, in which the binders contain~
A) 25 - 90 wt.~ of one or more hydroxy-functional I (meth)acrylic copolymers, obtainable from - ~ -¦ al) 10 - 30 wt.~ styrene and/or one or more styrene derivatives a2) 20 - 40 wt.~ of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, . . .
a3) 5 - 15 wt.~ of one or more hydroxyalkyl esters of (meth)acrylic acid, -. ;.' a4) 1 - 15 wt.~ of (meth)acrylic acid, ;'~
. ' . ;, 2 1 3 '~
a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, '.'~ :'', ) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from bl) 5 - 20 wt.~ styrene and/or one or more styrene ~;
derivatives, ., . .,, ~ , . .
b2) 5 - 20 wt.~ caprolactone, i~ -b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, -~
b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, preferably 10 to 30 wt.% of one or more hydroxy-functional polyesters, D) 5 - 35 wt.~ of one or more blocked polyisocyanates and ;
E) 5 - 30 wt.% of one or more aminoplastic resins, the sum of components al) to a5), bl to b5) and A to E) being 100 in each case.
The (meth)acrylic copolymers in the coating agents according to the inventio~ can be manufactured by radical copolymerisation by conventional methods. The solution polymerisation method is preferred for synthesis of the (meth)acrylic copolymers (components A and B) used in the coating agents according to the invention. In this method the solvent is placed in the reaction vessel, heated to boiling~
..
., .~.
~ 1 3 S '~
point, and the mixture of monomers and initiators is added ~-continuously during a predetermined time.
The term "(meth)acrylic" used in the present description and claims is synonymous for "acrylic and/or methacrylic".
Polymerisation is brought about e.g. at temperatures between 80C and 160C, preferably 100C to 150C.
r-The polymerisation reaction can be started with known polymerisation initiators, e.g. per- or azo-compounds which thermally decompose into radicals in a first-order reaction.
The nature and amount of initiator are chosen so that a substantially constant supply of radicals is available at the polymerisation temperature during the intake phase. `-The following are examples of initiators preferably used for polymerisation: dialkyl peroxides such as di-tert.-butyl peroxide, di-cumyl peroxide; diacyl peroxides such as di-benzoyl peroxide, di-lauroyl peroxide; hydroperoxides such as cumene hydroperoxide, tert. butyl hydroperoxide; peresters such as tert. butyl perbenzoate, tert. butyl perpivalate, ~ ~
tert. butyl-per-3,5,5-trimethyl hexanoate, tert. butyl-per-2- ~ `;
ethyl hexanoate; peroxydicarbonates such as di-2-ethyl hexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate; perketals such as 1,1-bis-(tert. butylperoxy)-3,5,5-trimethyl -cyclohexane, 1,1-bis- (tert.butylperoxy)cyclohexanei ketone ~ -peroxides such as cyclohexanone peroxide or methyl isobutyl ketone peroxidei azo compounds such as 2,2~-azo-bis(2,4-dimethyl valeronitrile), 2,2'-azo-bis-(2-methyl butyronitrile), 1,1'-azo-bis-cyclohexane carbonitrile or azo-bis-isobu~yronitrile. `~
Preferably the polymerisation initiators, more particularly the peresters, are added in a proportion of 0.2 to 5 wt.~ of the weighed-in quantity of monomers.
-` 21 3 ~ ~ ~ 2 The organic solvents advantageously used in solution ~.
polymerisation are conventional lacquer solvents, such as can also be used later ln the coating agents according to the invention, e.g. glycol ethers such as ethylene glycol dimethyl ether; glycol ether esters such as ethyl glycol acetate, butyl glycol acetate, 3-methoxy-n-butyl acetate, butyl diglycol acetate, methoxypropyl acetate, esters such as butyl acetate, ---isobutyl acetate, amyl acetate; or ketones such as methyl `- -~
ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone or isophorone. Alcohols such as methanol, ethanol, propanol, butanol, aromatic hydrocarbons such as ~`
xylene, Solvesso 100 (registered trade mark for a mixture of aromatic hydrocarbons with a boiling range of 155 to 185C) ~ :
and aliphatic hydrocarbons can also be used, blended with the aforementioned solvents.
In order to adjust the molecular weight, particularly in the .
preferred solution polymerisation, use can be made of chain transfer agents such as mercaptans, thioglycolic acid esters, chlorinated hydrocarbons, cumene or dimeric alpha-methyl styrene. ~ .
The polymerisation conditions (reaction temperature, intake time of the monomer mixture, concentration of solvent) are adjusted so that the (meth)acrylic copolymers for the coating agents produced according to the invention have a weight ~ :~
average molecular weight (determined by gel permeation chromatography using polystyrene as a calibrating substance) of 2500 - 10000.
~ ' :
The hydroxyl group-containing (meth)acrylic copolymers in the :
coating agents produced according to the invention are preferably situated in a glass transition temperature range of -20C to +40C, calculated from the glass transition temperature of the homopolymers of the individual monomers as given in the literature (Fox equation, see e.g. Polymere Werkstoffe, Batzer, 1985, page 307). .
:' ~
. ' :~-1 3 ~ 2 The monomers for producing the hydroxy-functional(meth)acrylic copolymers (component A) and used as component a2) are e.g.
glycidyl and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids (e.g. the -~ ;
commercial products CARDURA E10 and VEOVA 10 produced by Shell AG). The other monomers for producing (meth)acrylic copolymers (components A and B) are e.g. styrene and/or styrene derivatives, such as vinyl toluene, p-methyl styrene or p-tert. butyl styrene, hydroxyalkyl esters of acrylic acid `~
or methacrylic acid such as beta-hydroxy-ethyl acrylate, beta-hydroxyethyl methacrylate, beta-hydroxypropyl acrylate, beta- ~ -hydroxypropyl methacrylate, butanediol-1,4- monoacrylate, butanediol-1,4-monomethacrylate, hexanediol-1,6-monoacrylate or hexanediol-1,6-monomethacrylate. Alternatively, at least partial use can be made of polyalkylene oxide -mono(meth)acrylates with 2 to 10 alkylene oxide units per molecule, or alkyl esters of acrylic acid or methacrylic acid; -methacrylates, methyl methacrylate, ethyl acrylate, ethyl methacrylate, isopropyl methacrylate, tert. butyl acrylate, ~ ~
n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, ; ~ -isobutyl methacrylate, cyclohexyl methacrylate, trimethyl cyclohexyl methacrylate, 2-ethyl hexyl acrylate, 2-ethyl hexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, isobornyl acrylate or isobornyl methacrylate.
In order to provide the (meth)acrylic copolymers A) and B) with carboxyl groups, (meth)acrylic acid is incorporated by polymerisation, preferably in quantities such that the resulting acid number is 1 to 30 mg KOH/g. In order to introduce hydroxyl groups into the (meth)acrylic copolymers A) and B), hydroxyalkyl esters of (meth)acrylic acid (a3 to b3) are used preferably in quantities such that the resulting hydroxyl numbers are 40 to 200 mg KOH/g. ;~
The polyesters optionally used as component C) are polycondensation products of polyvalent polycarboxylic acids ~-2 1 3 ~ ~ 1 2 (e.g. dicarboxylic acids) or anhydrides thereof or polyhydric polyols, optionally also using monocarboxylic acids. These polymers are usually prepared with an excess of alcohol. The OH numbers are e.g. about 30 to 200, preferably 60 to 160 mg ~ - -KOH/g. The acid numbers are e.g. 1 to 50, preferably 5 to 30. --The weight average molecular weight is e.g. 500 to 4000, i~
preferably 1000 to 2000 g/mol. The following are examples of suitable polycarboxylic acids: o-phthalic acid (anhydride) isophthalic acid, terephthalic acid, tetrahydrophthalic acid (anhydride), 1,2-cyclohexane dicarboxylic acid (anhydride), 1,3-cyclohexane dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, 4-methyl hexahydrophthalic acid (anhydride), endomethylene tetrahydrophthalic acid (anhydride), trimellitic acid (anhydride), succinic acid (anhydride), glutaric acid, adipic acid, azelaic acid, sebacic acid, butane tetracarboxylic acid or dimeric fatty acid.
The polyesters can also contain small proportions of condensed `~
maleic acid anhydride. Optionally the aforementioned polycarboxylic acids can be used together with natural or synthetic monocarboxylic acids such as benzoic acid, tert.
butyl benzoic acid, lauric acid, isononanoic acid or fatty acids from naturally-occurring oils.
The following are examples of suitable alcohol components for preparing the polyesters: diols such as ethylene glycol, ;~
diethylene glycol, triethylene glycol, polyethylene glycols, propanediols, polypropylene glycols, butanediols, hexanediols, neopentyl glycol, cyclohexane diol, cyclohexane dimethanol, trimethyl pentane diol, ethyl butyl propane diol, or polyvalent alcohols such as trimethylol ethane, trimethylol propane, di-trimethylol propane, glycerol, pentaerythritol, ;~
di-pentaerythritol or tris-hydroxyethyl isocyanurate. -The polyesters can contain a modification component in the form of glycidyl esters of alpha, alpha~-di-substituted -~
monocarboxylic acids and epsilon caprolactone.
:,'. ~...`-Component D) in the coating agents according to the invention comprises blocked aliphatic or cyclo-aliphatic polyisocyanates in conventional use in the lacquer sector, e.g. diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate or 1,3- dimethyl-cyclohexyl-1,3-diisocyanate. Other examples of aliphatic or cycloaliphatic polyisocyanates are biuret group- ~ -containing products of a reaction between 3 mols of hexamethylene diisocyanate and one mol of water, with an NCO ;
content of about 22%; isocyanurate group-containing poly-isocyanates prepared by trimerisation of 3 mols of diisocyanate, e.g. hexamethylene diisocyanate or isophorone diisocyanate trimers, or urethane group-containing poly-isocyanates, obtained by a reaction between 3 mols of diisocyanate and 1 mol of triol. Isophorone diisocyanate trimers are preferably used.
The blocking agents can be conventional CH acids, NH- or OH-functional compounds, which bring about cross-linking under the hardening conditions, e.g. CH-acid esters such as aceto-acetic alkyl esters, malonic acid dialkyl esters, epsilon caprolactam, alcohols such as tert. butanol or oximes such as methyl ethyl ketoxime. Malonic acid dialkyl esters and oximes are preferred. It may be advantageous simultaneously to use various masking agents, either inside a polyisocyanate molecule or in a mixture.
It has been found that the coating agents of the invention provide particularly light and essentially yellowing-free coatings, if blocked ~ h polyisocyanates are used as component û) which are prepared by reaction of `:~ ~ .
free isocyanates under water-free conditions with blocking agents containing ;~
acid hydrogen, in the presence of basic catalysts, wherPin one or more alkali hydroxides are used as .basic catalysts. The thus obtained blocked ~ `:-polyisocyanates.have a particularly low alkali content due to the use of :-:
:: .....
: ~;:
:
-" 21~ 112 g ~ ., . . ~ ~. .
basic catalysts. Said content is preferably less than 100 ppm, particularly preferably less than 80 ppm and less than 50 ppm, calculated ad the weight of the alkali metals and based on the weight of the blocked isocyanates. `
.,:: ~ ~;.
The above mentioned process can be applied to any isocyanates with free isocyanate functions. It is, e.g. possible to use the above mentioned polyisocyanates.
.:
Know blocking agents containing acid hydrogen may be used for the above mentioned preparation of the polyisocyanates, e.gO the blocking agents examplified above. Specific examples are dialkyl malonic esters and alkyl acetoacetic esters. The alkyl groups of the esters, which in the dialkyl malonic ester may be the same or different, have preferably 1 to 4 carbon atoms.
When preparing the polyisocyanates as explained above, the molar ratio of the blocking agents containing acid hydrogen to the NCO groups of the isocyanates, for example, ~ .
the ratio of the dialkyl malonic esters and/or alkyl acetoacetic esters to NCO groups may range, for example, from 0.5:1 to 1:1.5. In the case of an NCO excess, the free NCO groups may optionally be reacted with other reactants. ~ ~-The catalysts used for the above explained process are alkali hydroxides, for example, alkali metal hydroxides such as lithium, sodium and/or potassium hydroxide. The water-free alkali metal hydroxides are used in preference. Lithium hydroxide is used in particular preference. The catalysts are used in catalytic .
quantities, for example, in quantities o, 0.1 to 2~ by wt., ~ -~
preferably 0.3 to 1~ by wt., based on the weight or isocyanate and blocking agent.
", 2 ~ 3, '' 1 2 , ~
.
The catalysts are used in solid form, for exam?le, in the form of a powde~
The addition of the blocking agent to the isocyanat- is ~-ca-ried out under wate--free conditions, pref~rably wlth the careful e:cclusion of moisture. The ~_~ctlon may be ca-ried out, for example, under a dry i.e-. cas, such as nitrogen. -The reaction may take place without solvents or in the presence of organic solvents. Suitable solvents a-=, in particular, those that do not react with polyisocya~at-s.
Examples of such solvents are orcanic solvents, suc:~ as ali?hatic and aromatic hydrocarbor.s, for ecample, x~lene, mix.ures of aliphatic and/or aromatic hvc-oca-bons, es.e~s and ethers.
In the process described above it is possible, after the reaction has ended, to remove easily the catalyst that remains undissolved in the reaction medium. This may be carried out, for example, by filtering or centrifuging.
optionally, the reaction product may be diluted beforehand or afterwards with solvents. In this case, solvents that can react with free polyisocyanates may also be used.
Suitable solvents are organic solvents, particularly solvents customary in lacquers, such as aromatic hydrocarbons, for example, xylene, aliphatic hydrocarbons, for example, n-hexane or cyclohexane, mixtures of aliphatic and/or aromatic hydrocarbons, ketones such as, for example, acetone, methylisopropyl ketone, esters such as, for example, butyl acetate or ethyl acetate, ethers such as, for example, methoxypropanol or butoxypropanol. ~lcohols, such as, for example, isopropanol or hexanol, may, however, also be used.
. - . ....................................... .
. .: ~ . . .
2 ~ 3 ~ ~ 1 2 The coating agents used according to the invention contain cross-linking agents such as aminoplastic resins (component E). The aminoplastic resins used can be conventional cross~
linking agents in the lacquer sector. Suitable aminoplastic resins include e.g. alkylated condensates obtained by reaction `~
o~ amino triazines and amido triazines with aldehydes. They are manu~actured by known methods by condensing amino or amido-group containing compounds such as melamine, benzoguanamine, dicyanodiamide, urea or N,N-ethylene urea in the presence of alcohols such as methyl, ethyl, propyl, isobutyl, n-butyl or hexyl alcohol with aldehydes, ~'~ .::~ ' ' , ; ~., , ,:i .i ~: . -.,. ~ ii.~, .
' ';.~-' .',-' ., "
, ., . ~ ",, j, . ~ ., .
.," ~ .~,"
~ . -: :~ ..
,',' '"''.-.- -,.~
~ ..
.. , ~ -:: :
12 2~ ~5 ~2 particularly formaldehyde. The reactivity of these amine resins is determined by the degree of condensation, the ratio of the amine or amide component to the formaldehyde and the nature of the etherification alcohol used.
The coating agents containing the binders for use according to the invention can contain the aforementioned solvents together with conventional lacquer adjuvants such as levelling agents, e.g. based on (meth)acrylic homopolymers, silicone oils, plasticisers such as phosphoric acid, phthalic acid or citric -acid esters, substances for influencing the flow properties, such as pyrogenic silicone oxide, microgels, urea group- -containing products obtained by a reaction between primary ~f amines and polyisocyanates, hydrogenated castor oil, curing ;~
accelerators for reacting the hydroxyfunctional binders according to the invention (components A, B and C) with blocked isocyanates (component D) and aminoplastic resins (component E); phosphoric acid, phosphoric acid esters, dicarboxylic acid semiesters, citric acidi organic metal salts such as dibutyl tin dilaurate, zinc naphthenate, bismuth tricarboxylate, or tertiary amino group-containing compounds such as triethylamine and light-excluding agents.
The coating agents according to the invention are particularly `
suitable for producing a transparent top layer during the manufacture of stoving multi-layer coatings. The top layer can be applied by the wet-on-wet method, when both layers are hardened simultaneously. The invention therefore also relates to the method of producing multi-layer coatings or using the coating agents for manufacturing them. The solvent-containing coatings according to the invention can be applied in the form of a transparent top lacquer on layers of aqueous or solvent-containing base lacquers for hardenable multi-layer coatings. ;
The coating agents according to the invention are applied by ~ ~
known methods such as spraying, immiersion, rolling or doctor ~`
blade. The top-lacquer layer is applied to the substrate, ~
-~` 21~5`~2 -:
which is optionally already covered with other lacquer layers. ~ ;
The coating agents according to the invention can also be applied by spraying, using supercritical carbon dioxide as a ~ ~-solvent. The content of organic solvents can be greatly reduced. After an evaporation phase, the applied coating agent is cross-linked, preferably by heating. The stoving temperatures are usually between 110 and 160C, preferably between 120 and 150C. The thickness of the stoved film is about 15 - 50 ~m. The result is a cross-linked, hard, glossy lacquer coating. One preferred embodiment is use o~ the coating agent according to the invention as a clear lacquer coating on a base lacquer. Operation can be wet-on-wet, or alternatively the base lacquer is previously dried by heating.
This results in particularly good adhesion between the two layers.
Coating agents formulated as clear lacquers according to the invention can be applied e.g. over base lacquers, which can contain conventional coating-lacquer pigments, preferably decorative pigments such as metallic pigments. The binder bases of the base lacquer preferably comprises polyester, polyurethane or acrylate resins. These binders can optionally be cross-linked by cross-linking agents, e.g. melamine or isocyanate derivatives.
The coating agents according to the invention are particularly suitable for top lacquers or clear lacquers, preferably for use in the motor-vehicle sector but also in other areas. The use of the coating agent according to the invention for multi~
layer lacquering is particularly suitable for lacquering mass-produced motor vehicles, but uses are also possible for other purposes, such as domestic appliances or for the furniture industry.
The coating agents according to the invention are particularly suitable for manufacturing a transparent top layer of a ~ ;
~ ~ 3 ~
stoving multi-layer coating. They are particularly suitable for lacquering of mass-produced car bodies and parts thereof.
The coating agents according to the invention can be applied -wet-on-wet on conventional, i.e. solvent-containing or aqueous, lacquer layers, when both layers are simultaneously hardened at elevated temperature. For example, transparent top layers applied to the clear lacquers according to the invention can be applied by the wet-on-wet process on conventional or aqueous base lacquers. The two layers can then be hardened simultaneously. The hardening temperatures are e.g. of the order of 120 to 150C. The hardening times are e.g. of the order of 20 to 40 minutes.
Accordingly the invention also relates to manufacture of multi-layer coatings or use of the coating agents according to the invention for producing top lacquer layers, e.g. clear -~ -lacquer layers, for hardenable multi-layer coatings. ~ ;
The following examples illustrate the invention. A11 parts are by weight.
Manufacture of the (meth)acrylic copolymers : :
Example of manufacture AC-1 173 g of SOL~ESSO 150 (product sold by Shell AG) and 5 g of ~ 0 n-butanol were placed in a 2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and were heated to 152C with agitation, after switching on the reflux condenser. During -six hours, a mixture of 67 g acrylic acid, 160 g styrene, 150 g butyl acrylate, 65 g 2-hydroxyethyl acrylate, 220 g CARDURA E10 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 22 g tert. butyl. peroctoate were continuously added. Next, the batch was additionally polymerised at 150C
:: ~
. . ; ~ ''`~`
2l3~2 for 4 hours, cooled to 80C and diluted with 62 g Solvesso 100 and 62 g n-butanol. ~ .
Example of manufacture AC-2 163 g SOLVESSO 150 (product sold by Shell AG), 5 g n-butanol ~ ~ -and 70 g VEOVA 10 (product sold by Shell AG) were placed in a - -~
2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and were heated to 152C with agitation, using a reflux condenser. A mixture of 47 g acrylic acid, 160 g styrene, 125 g butyl methacrylate, 110 g 2-hydroxyethyl methacrylate, 150 g CARDURA E10 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 22 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 152C for 5 hours, cooled to 80C
and diluted with 72 g Solvesso 100 and 60 g n-butanol.
Example of ma~ufacture AC-3 232 g SOLVESSO 100 (product sold by Shell AG) was placed in a 2-litre 3-necked ground-glass flask equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and heated to 148C with agitation, after switching on the reflux condenser. A mixture of 14 g acrylic acid, 65 g styrene, 224 g butyl methacrylate, 141 g 2-hydroxypropyl methacrylate, 45 g 2-hydroxyethyl acrylate, 52 g lauryl acrylate, 89 g caprolactone, 4 g di-tert. butyl peroxide and 16 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 148C
for 5 hours, cooled to 80C and diluted with 46 g Solvesso 100 and 72 g n-butanol.
Example o~ ma~u~acture AC-4 185 g of SOLVESSO 100 (product sold by Shell AG) and 5 g butanol were placed in a 2-litre 3-necked ground-glass flask .. . :. .
16 213 ~ '1 12 equipped with an agitator, contact thermometer, globe-shaped condenser and dropping funnel, and heated to 152C with agitation, after switching on the reflux condenser. A mixture of 67 g acrylic acid, 160 g styrene, 84 g butyl acrylate, 87 g 2-hydroxyethyl acrylate, 220 g CARDURA E10 (product sold by Shell AG), 16 SOLVESSO 100 (product sold by Shell AG), 16 g di-tert. butyl peroxide and 16 g tert. butyl peroctoate was continuously added during 5 hours. The batch was then additionally polymerised at 148C for 5 hours, cooled to 80C
and diluted with 79 g SOLVESSO 100 and 65 g n-butanol. -~
~r ~ ~ ~
Example of manufacture PE~
170.3 g hexanediol-1,6 and 128.9 g trimethylol propane was placed and melted in a 2-litre 3-necked flask equipped with a thermometer, agitator and condenser. Next, 0.3 g of ~`
hypophosphorous acid, 37 g xylene, 228.2 g hexahydrophthalic acid anhydride and 278.6 g dimeric fatty acid was poured in with agitation, heating and under a stream of inert gas, and heated to 220C at the rate of 20C per hour. After an acid number of 22 had been reached, the mixture was cooled to 100C
and diluted with 156 g Solvesso 100 (product sold by Shell ~;
AG).
. ~:
Exam~le 1 Manufacture of a clear lacouer , ~, A single-component clear lacquer was manufactured by homogeneous mixing of 24.4 parts of the resin solution in Example AC-3 with 28 parts of the resin solution in Example AC-1, 10.75 parts Solvesso 100, 7.5 parts of a 70% butyl glycolic solution of the isocyanurate of isophorone diisocyanurate blocked with butanone oxime, 3 parts butanol, 16.6 parts of a commercial 58% solution of a highly reactive butanol-etherified melamine resin in butanol/xylene, 3.2 parts ~ ~
of butyl glycol acetate, 1.2 parts of a 1 : 1 mixture of ~;
' ' ' ~ ' ':
.,,, ~-.~ -17 ~ 2 commercial light-excluding agents based on benzotriazole and HALS, 1 part of silicone oil, 0.35 parts o~ dibutyl tin ~ :.
dilaurate and 4 parts of butyl diglycol. -~
Exam~le 2 Manufacture ~f a clear lacouer In the same manner as in Example 1, a single-component clear lacquer was produced from 31.6 parts of the resin solution in Example AC-1, 13.8 parts of the resin solution in Example PE-1, 20.2 parts of a commercial 70~ butanolic solution of a melamine resin co-etherified with methanol and butanol, 11.7 parts of a solution of the blocked polyisocyanate from clear- :~
lacquer example 1, 11.24 parts of Solvesso 100, 1.2 parts of the light-excluding agent mixture in clear-lacquer example 1, 0.8 parts butanol, 3.3 parts butyl glycol acetate, 1 part of `~
silicone oil, 0.76 parts of dibutyl tin dilaurate and 4.4 - -~
parts of butyl diglycol.
Example 3 Manufacture of a clear lacouer In the same manner as in Example 1, a single-component clear lacquer was produced from 46.2 parts of the resin solution in ;~
example AC-4, 13.5 parts Solvesso 100, 7.1 parts of a commercial 70~ butanolic solution of a melamine resin co- ~.;
etherified with methanol and butanol, 2'.4 parts of a 70 Solvesso 100 solution of an isocyanurate of isophorone diisocyanate blocked with malonic acid:diethyl ester, .
1.2 parts of the light-excluding agent mixture in clear-lacquer example 1, 0.84 parts of butanol, 3.5 parts of butyl glycol acetate, 1 part of silicone oil, 0.76 parts of dibutyl tin dilaurate and 4.5 parts of butyl diglycol.
` ` !
''; ~''' 18 2t3~2 Sheet-metal bodies previously coated with commercial cathodically depositable electrodeposition lacquers (KTL) conventionally used for lacquering mass-produced cars (KTL;
18 ~m) and commercial fillers (35 ~m) were lacquered with commercial water-dilutable metallic-based lacquer in a dry .
layer thickness of 15 ~m and pre-dried at 80C for 6 minutes.
Directly afterwards, the clear lacquer in clear-lacquer examples 1, 2 and 3 was applied by spraying wet-on-wet in a dry layer thickness of 35 ~m and stoved at 140C (the object temperature) for 20 minutes after 5 minutes' ventilation at room temperature.
Corresponding comparative experiments were made with prior-art lacquers. The results are given in the following Table. The tests were carried out in accordance with general industrial standards. The clear lacquers were tested for resistance to sulphuric acid by the drop test, using 10% and 38% H2SO4 ~- -respectively. The metal test sheets were placed on a heatable plate and heated to 65C. Care was taken that the sheets rested flat, to ensure optimum transmission of temperature. ~;~
At the end of the heating-up phase, i.e. at 65C, one drop per minute was applied to the clear-lacquer surface. The total time was 30 minutes. At the end of the test time, the lacquer was washed off with water. When necessary, a brush could additionally be used for cleaning.
In order to judge the resistance to sulphuric acid, the period of action, in minutes, is given at which the first visible ;~
change in the film (swelling) damage (dulling) or corrosion of base lacquer occurs.
, ., :, ''.'.'.'.
',. '~;",' .' '' ~ ~ 3 ~ l~ '1 2 : , . ~ .
Table Clear lacquers according to the invention~
ExamDle: 1 2 3 .'''~'~',',7 '' Yellowing: _ None_ Slight None _ " -Content of solids for ~rocessing (%) 47.1 51.2 48.1 20qloss 84 _ 88 88 Pendulum hardness~
(Number of vibrations) 75 77 84 ~-.
Sulphuric acid test 10% H2S04, 30'60C
Swelling 13 17 14 Dulling 21 22 30 Corrosion of base coat 24 30 ~30 Sulphuric acid test :~
, 0 0 ~ ~ 0 ~
~ O A2 C~ V4, ~ u ~, v Swelling 20 11 13 Dulling ,30 ~30 28 Corrosion of base coat 28 30 >30 ,~
Pencil hardness: HB HB HB
;" .~ ','`;~''' Clear lacquers used for comparison JP-A GB-A JP-A DE-A
. " ~
246483 2254328 158079 4204518 : ~;
Example 2 4 1 7 Yellowing: Sliaht Strong Stronq None Contents of.
solids for processinq (%) 32.4 41.5 58.1 50.8 20gloss 83 58 29 82 :. ~ ..: . :~.: .......
" ,, .. ;.-.-., .~
.. , ,: . . ~, : .. . ..: .
2 ~ 3 ;~
Pendulum hardness (number of vibrations) 84 85 38 82 ~ ~ ~
Sulphuric acid ~ ~-test 10~ H2SO4, 30'60C
Swelling 14 12 10 10 Dulling ~30 ,30 13 13 Corrosion of base coat 22 18 19 19 Sulphuric acid test ;~
39~ H2SO4, 30'60C
Swelling 9 2 2 5 Dulling ~30 11 11 11 Corrosion of base coat 25 15 15 13 -Pencil hardness HB F 2B HB _ ~ ' As the preceding Table shows, the coating agents according to the invention, as compared with JP-A-246 483, are characterised particularly by an improved solids content and improved resistance to acid at elevated temperatures. As compared with GB-A-2 254 328 the coating agents according to the invention likewise have an improved solids content, with improved gloss and improved resistance to acid. According to the invention, the gloss, pendulum hardness and resistance to acid are also improved compared with JP-A-158 079. By comparison with DE-A-42 04 518 the invention provides considerably improved resistance to acid. -"';';'` '~ ',.''''',.
:;~;' ,, '-.' . . ~,:
.. .. .~.. -2 1 3 ~
.~
Example of manufacture Pl~
,: ~
Reaction of isophorone diisocyanate-isocyanurate with diethyl malonate :.. - ~, ,~,:
376 (P = parts by weight) of isophorone diisocyanate-isocyanurate : ~
(obtainable from Huls under the trade name ~estanat IPDI T-1890) are -. .
dissolved in 350 P of Solvesso lO0 with heating to 80 C.
Subsequently, 4 P of water-free lithium hydroxide are added. Then 271 P of diethyl malonate are added dropwise in such a way that the reaction temperature does not exceed 90 C. The reaction mixture is kept at 90 C until an NCO
content of c0.5~ is reached. The undissolved lithium hydroxide is filtered by filtration ove- G 1 ~m filter.
. .. ~
Final values: solids (1 h/150 C): 60 /, visccsi-y ~ ~
(25 C): 2400 mPas, colour number (C-a-~-.e-): 2; l thium'~'''''i~,~,f content (atomic absorption spectroscopy): ~8 p_m ~ ~
~- :. ,-, :.
Example of manufacture Pl-2 Reaction of hexamethylene diisocyanate-isocyanurate wlth diethyl malonate -~
In the same way as e~cample 1), 351 ~ of ~e:camethylen~
diisocyanate-isocyanurate (obtainaDl- f-_~ R~.c-.--~^ulenc under the trade name Tolonat HDT/100) G-e _eac~ed wi.h ... ,.., ~ ~ .
' '~ ',~
- .. . ~...
... ~ .. ..;
,. ,. ~ . . :.
``````` '`.~
,": ~
1 3~ 2 ~2 :~
~ ~ ''~.','.`
295 P of diethyl malonate in 350 P of Solvesso 100 in the :
presence of .3 P of water-free lithium hydroxide. ~-~
Final values: solids (1 h/150 C): 60.3~; viscosity ; ~,' !~' (25 C): 680 mPas; colour number (Gardner): 1. '1'i~''"'''.,"~
Example of manufacture P1-3 Reaction of isophorone diisocyanate-isocyanurate with ethyl ~ a 10 acetoacetate In the same way as exam~le 1), alo P of Vestanat I~DI ;;~
T-1890 are reacted with 240 P of ethyl acetcacetat~ ir.
350 P of Solvesso 100 in the presence of ~.1 F of wate~
15 free lithium hydroxide. "~
Final values: solids (1 h/150 C): 61~; vis~~sitv (25 C): 1300 mDas; colcur numbe_ (G~rc-~
If the polyisocyanates of Example of manufacture Pl-1, Pl-2 and Pl-3 are used as component D), the obtained coatings are particularly .. `
free of yellowings. :
`~ ~
Claims (11)
1. Coating agents for producing transparent top layers on multi-layer coatings and containing binders based on hydroxy-functional(meth)acrylic copolymers, blocked polyisocyanates, aminoplastic resins and, optionally, hydroxy-functional polyester resins together with conventional lacquer additives and solvents, characterised in that the binders contain:
A) 25 - 90 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from a1) 10 - 30 wt.% styrene and/or one or more styrene derivatives a2) 20 - 40 wt.% of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, a3) 5 - 15 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, a4) 1 - 15 wt.% of (meth)acrylic acid, a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, B) 0 - 40 wt.%, of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from b1) 5 - 20 wt.% styrene and/or one or more styrene derivatives, b2) 5 - 20 wt.% caprolactone, b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, of one or more hydroxy-functional polyesters, D) 5 - 35 wt.% of one or more blocked polyisocyanates and E) 5 - 30 wt.% of one or more aminoplastic resins, the sum of components a1) to a5), b1 to b5) and A to E) being 100 in each case.
A) 25 - 90 wt.% of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from a1) 10 - 30 wt.% styrene and/or one or more styrene derivatives a2) 20 - 40 wt.% of one or more glycidyl esters and/or vinyl esters of alpha, alpha'-dialkyl-substituted branched aliphatic monocarboxylic acids, a3) 5 - 15 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, a4) 1 - 15 wt.% of (meth)acrylic acid, a5) 15 - 35 wt.% of one or more (meth)acrylic acid esters, B) 0 - 40 wt.%, of one or more hydroxy-functional (meth)acrylic copolymers, obtainable from b1) 5 - 20 wt.% styrene and/or one or more styrene derivatives, b2) 5 - 20 wt.% caprolactone, b3) 10 - 30 wt.% of one or more hydroxyalkyl esters of (meth)acrylic acid, b4) 1 - 3 wt.% (meth)acrylic acid, b5) 30 - 50 wt.% of one or more (meth)acrylic acid esters, C) 0 - 40 wt.%, of one or more hydroxy-functional polyesters, D) 5 - 35 wt.% of one or more blocked polyisocyanates and E) 5 - 30 wt.% of one or more aminoplastic resins, the sum of components a1) to a5), b1 to b5) and A to E) being 100 in each case.
2. Coating agents according to claim 1, characterised in that components A) and B) comprise (meth)acrylic copolymers, each with a hydroxyl number of 40 - 200 mg KOH/g, an acid number of 1 - 30 mg KOH/g, a weight average molecular weight of 2500 to 10000 g/mol and a glass transition temperature of -20°C to +40°C.
3. Coating agents according to claim 1 or 2, characterised in that the component C) used comprises one or more polyesters with an acid number of 1 - 50 mg KOH/g, a hydroxyl number of 30 - 200 mg KOH/g and a weight average molecular weight of 500 - 4000 g/mol.
4. A coating agent according to any of claims 1 to 3, characterised in that it is formulated without pigments or with transparent pigments serving as clear lacquer.
5. Coating agents according to any of claims 1 to 4 characerised in that the blocked polyisocyanates of component D) were prepared by reaction of polyisocyanates having free NCO groups under water-free conditions with blocking agents containing acid hydrogen in the presence of basic catalysts, wherein one or more alkali hydroxides are used as basic catalysts.
6. Coating agents according to claim 5, wherein lithium hydroxide is used as alkali hydroxide.
7. Coating agent according to claim 4 or 5, wherein dialkyl malonic esters and/or alkyl acetoacetic esters are reacted as blocking agents.
8. A method of producing multi-layer coatings by applying a base lacquer layer on to a substrate, optionally already covered with one or more coating layers, and covering the resulting base lacquer layer, after drying or wet-on-wet, with a top lacquer layer of a transparent coating agent according to any of claims 1 to 7.
9. A method according to claim 8, characterised in that it is for the purpose of producing multi-layer lacquer coats on motor-vehicle bodies or parts thereof.
10. Use of the coating agents according to any of claims 1 to 7, for producing transparent top layers of multi-layer coatings, more particularly in the motor-vehicle sector.
11. Objects provided with multi-layer coatings containing a top lacquer coating comprising a coating agent according to any of claims 1 to 7.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4338703.9 | 1993-11-12 | ||
| DE19934338703 DE4338703C1 (en) | 1993-11-12 | 1993-11-12 | Transparent, non-yellowing, top:coat compsn., esp. for painting cars |
| DE4405042A DE4405042A1 (en) | 1994-02-17 | 1994-02-17 | Process for the preparation of blocked isocyanates, the blocked isocyanates obtained and their use |
| DEP4405042.9 | 1994-02-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2135412A1 true CA2135412A1 (en) | 1995-05-13 |
Family
ID=25931177
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002135412A Abandoned CA2135412A1 (en) | 1993-11-12 | 1994-11-09 | Coating agents for transparent coating-lacquer layers, and use thereof in methods of producing multilayer coatings |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0653468A3 (en) |
| JP (1) | JPH07188603A (en) |
| KR (1) | KR950014248A (en) |
| CA (1) | CA2135412A1 (en) |
Families Citing this family (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100486798B1 (en) * | 1995-05-02 | 2005-12-21 | 이.아이,듀우판드네모아앤드캄파니 | Scratch-Resistant Coating Composition |
| DE19525375A1 (en) * | 1995-07-12 | 1997-01-16 | Herberts Gmbh | Coating agents, their use and process for the production of multilayer coatings |
| DE19529124C1 (en) * | 1995-08-08 | 1996-11-21 | Herberts Gmbh | Acid-resistant coating material, pref. clear top-coat for cars |
| JPH09125000A (en) * | 1995-11-01 | 1997-05-13 | Asahi Chem Ind Co Ltd | Topcoat coating and top coating method |
| JPH09168764A (en) * | 1995-12-19 | 1997-06-30 | Nof Corp | Method for forming paint film and coated article |
| US5977256A (en) * | 1996-04-29 | 1999-11-02 | E.I. Du Pont De Nemours And Company | Scratch-resistant coating composition |
| DE19704020A1 (en) * | 1997-02-04 | 1998-08-06 | Herberts Gmbh | Copolymers containing hydroxyl groups and process for their preparation |
| DE19725742C2 (en) | 1997-06-18 | 1999-11-04 | Herberts & Co Gmbh | Use of urea compounds and formaldehyde-providing substances in clear lacquer coatings |
| US6458885B1 (en) * | 1998-05-29 | 2002-10-01 | Ppg Industries Ohio, Inc. | Fast drying clear coat composition |
| DE19846971A1 (en) * | 1998-10-12 | 2000-04-20 | Basf Coatings Ag | Polyurethane composition, useful as a clear topcoat or lacquer for polymers, contains specified amount of a UV absorber |
| EP1163306A1 (en) * | 1999-03-17 | 2001-12-19 | E.I. Du Pont De Nemours And Company | High solids clear coating composition |
| AT409967B (en) | 2000-10-17 | 2002-12-27 | Solutia Austria Gmbh | TWO-COMPONENT SYSTEMS BASED ON WATER-SOLUBLE POLYESTERS AND CAPPED ISOCYANATES FOR THE FORMULATION OF WATER-THINNABLE BURNING LACQUERS |
| US6979713B2 (en) * | 2002-11-25 | 2005-12-27 | 3M Innovative Properties Company | Curable compositions and abrasive articles therefrom |
| CA2461835A1 (en) * | 2003-03-28 | 2004-09-28 | Kansai Paint Co., Ltd. | Paint film forming method |
| CA2521343C (en) * | 2003-04-24 | 2009-04-14 | Kansai Paint Co., Ltd. | Thermosetting liquid coating composition for aluminum wheel and method of coating aluminum wheel |
| DE102005036584A1 (en) * | 2005-08-01 | 2007-02-15 | Basf Ag | Mixed etherified melamine-formaldehyde resins |
| US8143341B2 (en) | 2006-03-29 | 2012-03-27 | Ppg Industries Ohio, Inc | Aqueous coating compositions |
| US20070244258A1 (en) * | 2006-03-29 | 2007-10-18 | Shanti Swarup | Clear coating compositions with improved scratch resistance |
| US8124688B2 (en) | 2006-03-30 | 2012-02-28 | Akzo Novel Coatings International B.V. | Coating composition comprising a reactive diluent of malonate |
| US20090053420A1 (en) * | 2007-08-20 | 2009-02-26 | Basf Corporation | Thermosetting coating compositions with multiple cure mechanisms |
| KR20100118839A (en) | 2009-04-29 | 2010-11-08 | 삼성전자주식회사 | Semiconductor memory device |
| CN105658747B (en) * | 2013-09-09 | 2017-09-29 | 关西涂料株式会社 | Coating composition and coated article |
| WO2015037280A1 (en) * | 2013-09-10 | 2015-03-19 | 関西ペイント株式会社 | Coating material composition and coated article |
| JP6869753B2 (en) * | 2016-03-09 | 2021-05-12 | 関西ペイント株式会社 | High solid content paint composition |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1418372A (en) * | 1973-05-09 | 1975-12-17 | Shell Int Research | Bulk copolymerization process |
| DE3918669A1 (en) * | 1989-06-08 | 1990-12-20 | Basf Lacke & Farben | CARBOXYL GROUPS AND GGF. COPOLYMERS CONTAINING TERTIARY AMINO GROUPS, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE IN COATING MEASURES |
| DE4204518A1 (en) * | 1992-02-15 | 1993-08-19 | Basf Lacke & Farben | METHOD FOR PRODUCING A TWO-LAYER PAINTING AND NON-AQUEOUS VARNISHES SUITABLE FOR THIS METHOD |
| DE4223183C1 (en) * | 1992-07-15 | 1993-07-15 | Herberts Gmbh, 5600 Wuppertal, De | Emulsifier-free thermo-curable coating as aq. emulsion - comprises self-emulsifying ester-based copolymers, polyester oligomers, water-(in)soluble amine resin crosslinking agents and capped poly:isocyanate(s) |
-
1994
- 1994-11-08 EP EP94117557A patent/EP0653468A3/en not_active Withdrawn
- 1994-11-09 CA CA002135412A patent/CA2135412A1/en not_active Abandoned
- 1994-11-10 KR KR1019940029425A patent/KR950014248A/en not_active Application Discontinuation
- 1994-11-11 JP JP6277428A patent/JPH07188603A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| KR950014248A (en) | 1995-06-15 |
| EP0653468A3 (en) | 1995-12-13 |
| JPH07188603A (en) | 1995-07-25 |
| EP0653468A2 (en) | 1995-05-17 |
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