NZ243485A

NZ243485A - Copolymer solutions based on the reaction product of unsaturated carboxylic acids, glycidyl esters, other unsaturated monomers and polysiloxanes; two component coating compositions

Info

Publication number: NZ243485A
Application number: NZ243485A
Authority: NZ
Inventors: Santos Antonio Manuel Dos
Original assignee: Synthopol Chemie Dr Koch
Priority date: 1991-07-20
Filing date: 1992-07-09
Publication date: 1994-06-27
Also published as: EP0528169A3; AU651901B2; ATE185354T1; DE59209754D1; ES2139581T3; DE4124167A1; CA2074104A1; AU1968492A; EP0528169B1; ZA925121B; EP0528169A2

Abstract

The invention relates to copolymer solutions of copolymers of the abovementioned type, which, after the copolymerisation, has an unusually high solids content (about 80 % by weight) and can be converted, with polyisocyanates into two-component coatings having a high solids content and good processing viscosity. Copolymers contain a cocondensed methoxy-functional polysiloxane. The copolymers can be converted with amino resins into binders for stoving coatings (baking coatings or paints) which, as improved varnishes for automotive finishes, give paint films which have excellent abrasion resistance in automatic car washes.

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £43485 243485 Priority D"J; .omo fJo^. texua'lv^ c^?Sr*ftv)«?9;. CpSys^/qs, <-9'HP,i.S~?lQai Cw:ii^!6lo i»pr;,;i{ic; lion filvc.1: Cl?cs; C<?SlrS7l]»',. SO,IO... 2 7 JUN 1994 *• I * a&i 1 Class Cont: ^ 0 '*/; Cfi^jc?05"/oHr;. <^5 I Patents Form No. 5 ~ Patents Act 1953 COMPLETE SPECIFICATION COPOLYMER SOLUTIONS BASED ON ADDITION PRODUCTS OF a,&-UNSATURATED CARBOXYLIC ACID WITH GLYCIDYL ESTERS AND COPOLYMERISABLE a,B-UNSATURATED MONOMERS We, SYNTHOPOL CHEMIE DR. RER. POL. KOCH GmbH & CO. KG, a company organised and existing under the laws of the Federal Republic of Germany, of Alter Postweg 35, D-2150 Buxtehude, Federal Republic of Germany, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: (to be followed by la) 1 24 3 A 8 5 The invention relates to copolymer solutions 5 based on addition products of a,0-unsaturated carboxylic acid with glycidyl esters and copolymerisable a-unsaturated monomers with and without hydroxyl groups. It also relates to the preparation of such hydroxyl-containing copolymers and to the use thereof in 10 clear or pigmented coatings. Hydroxyl-containing copolymers based on (meth)-acrylates and reaction products of acrylic acid and glycidyl esters of a-alkylalkanemonocarboxylic acids and/or a,a-dialkylalkanemonocarboxylic acids which can be 15 processed together with organic polyisocyanates to form coatings are known. DE-B-1 668 510 describes copolymers of addition products of a,0-ethylenically unsaturated carboxylic acids with glycidyl esters and copolymerisable a,£-unsaturated monomers with and without hydroxyl 20 groups. DE-C-2 603 259 discloses two-component coatings containing specific binders. These binders are copolymers based on styrene, methyl methacrylate, acrylic acid and glycidyl esters of a-alkylalkanemonocarboxylic acids and/or a,a-dialkylalkanemonocarboxylic acids obtained by 25 heating with simultaneous esterification and polymerisation in inert solvents in the presence of polymerisation initiators with or without chain terminators. The solids contents of prior art copolymer solutions on termination of the simultaneous esterifica-30 tion and copolymerisation is not more than 55% by weight or, according to page 4 of DE-A-3 740 774 (component A), about 65% by weight, although the objective of the latter reference was a particularly high solids content. The object of the invention is 35 1. To provide copolymer solutions which have a significantly higher solids content, 2. To provide processes for preparing the novel copolymer solutions, I I - 2 - 24 3 48 5 The binders obtainable from the novel copolymer solutions shall when used with difunctional and/or higher polyisocyanates have an increased solids content for the same viscosity. This means that the two-component coatings prepared from the copolymer solutions or the binder of the invention can be applied quickly, for example by omitting one or more spraying operations. Furthermore, because of the higher solids content of the ready-prepared two-component coatings less organic solvent shall be emitted into the environment. The copolymer solutions or binders, when combined with aliphatic polyisocyanates, shall produce air-and oven-drying high-solids two-component finishes of high mechanical, chemical, weathering and ultraviolet radiation resistance. The provision of copolymer solutions or binders or clear or pigmented coatings with an increased solids content that lead to coatings of high gloss, good build, good flow, less environmental pollution and improved processing reliability. The copolymer solutions or binders shall be proces-sible into two-component coatings highly suitable for use not only as automotive original equipment coatings but also as automotive refinish coatings. The binders mentioned earlier under point 3 shall result in improved clear coatings for automotive topcoating by producing paint films with excellent abrasion resistance in car washes. The novel polymer solutions shall also be combinable with amino resins to form binders which are processed to form baking finishes with or without pigments. It shall also be possible to add polyisocyanates to the copolymer-amino resin combination. Again, the foregoing binders are suitable for improved clear baking finishes for automotive topcoating which provide paint films with excellent abrasion resistance in car washes. - 3 - 24 3 4 85 It has been found that this object is achieved by providing a copolymer solution which contains a hydroxyl-containing copolymer based on addition products of a,£-unsaturated carboxylic acid with glycidyl esters and copolymerisable a ,£-unsaturated monomers with and without hydroxyl groups, said copolymer being characterised in that it consists essentially of a hydroxyl-containing copolymer obtainable from a) 10 to 30% by weight of glycidyl esters of a-alkyl alkanemonocarboxylic acids and/or a, a-dialkylalkane-monocarboxylic acids, b) 5 to 12% by weight of methacrylic acid, c) 10 to 27% by weight of hydroxyalkyl methacrylate having 1 to 6 carbon atoms in the hydroxylalkyl radical, d) 10 to 38% by weight of styrene, e) 1 to 5% by weight of polypropylene glycol mono- methacrylate having an average molecular weight of 350 to 387, f) 3 to 20% by weight of alkyl methacrylate having 1 to 8 carbon atoms in the alkyl radical, g) 9 to 20% by weight of solvent-free, reactive, methoxy-functional polysiloxane, the percentages of components a, b, c, d, e, f and g always adding up to 100% by weight. An advantageous embodiment of the copolymer is obtainable from: a) 17 to 25% by weight of glycidyl esters of a-alkyl alkanemonocarboxylic acids and/or a, a-dialkylalkane-monocarboxylic acids, b) 7 to 12% by weight of methacrylic acid, c) 15 to 26% by weight of 2-hydroxyethyl methacrylate, d) 17 to 28% by weight of styrene, 243485 - 4 - e) 1 to 3% by weight of polypropylene glycol mono- methacrylate having an average molecular weight of 350 to 387, f) 5 to 15% by weight of methyl methacrylate, g) 12 to 17% by weight of solvent-free, reactive, methoxy-functional polysiloxane, the percentages of components a, b, c, d, e, f and g always adding up to 100% by weight. A preferred embodiment of the copolymer is obtainable from: a) 18 to 24% by weight of glycidyl esters of a-alkylalkanemonocarboxylic acids and/or a, a-dialkylalkane-monocarboxylic acids, b) 6 to 12% by weight of methacrylic acid, c) 17 to 22% by weight of 2-hydroxyethyl methacrylate, d) 20 to 28% by weight of styrene, e) 1 to 3% by weight of polypropylene glycol mono-methacrylate having an average molecular weight of 350 to 387, f) 8 to 12% by weight of methyl methacrylate, g) 12 to 17% by weight of solvent-free, reactive, methoxy-functional polysiloxane, the percentages of components a, b, c, d, e, f and g always adding up to 100% by weight. Another preferred embodiment of the copolymer solution is obtainable from: a) 8 to 22% by weight of glycidyl esters of a-alkyl alkanemonocarboxylic acids and/or a, a-dialkylalkane-monocarboxylie acids, b) 7 to 10% by weight of methacrylic acid, c) 19 to 22% by weight of 2-hydroxyethyl methacrylate, d) 20 to 28% by weight of styrene, e) 1 to 3% by weight of polypropylene glycol mono- methacrylate having an average 24 34 8 5 - 5 - molecular weight of 350 to 387, f) 9 to 11% by weight of methyl methacrylate, g) 13 to 17% by weight of solvent-free, reactive, methoxy-functional polysiloxane, 5 the percentages of components a, b, c, d, e, f and g always adding up to 100% by weight. The most preferred embodiment of the above-mentioned copolymer solutions is characterised in that, 10 after its preparation, it consists of A) 15.0-25.0% by weight, preferably 15 to 20% by weight, of customary inert paint solvents, preferably with boiling points of 150 to 200°C, and 15 B) 75.0-85.0% by weight, preferably 85 to 80% by weight, of hydroxyl-containing copolymers. It has been found that such a copolymer solution, when used with difunctional and/or higher polyisocyanates 20 produces, compared with the prior art, an increased solids content for the same viscosity or a reduced viscosity for the same solids content. What is more, it has coating advantages, such as improved gloss, build, flow, processing reliability as well as the high solids con-25 tent, and also better environmental properties. The copolymer solution of the invention is prepared by solution polymerisation. This involves an addition reaction between components a and b with a simultaneous condensation with component g by elimination 30 of methanol, which is removed in the reflux of the boiling reaction mixture. This process comprises introducing the solvents and the glycidyl esters of a-alkyl-alkanemonocarboxylic acids and/or a,a-dialkylalkane-monocarboxylic acids into the reaction vessel as initial 35 charge, heating to the boil, and continuously adding the mixture or mixtures of monomers, optionally carboxy-epoxy catalysts and initiator continuously over about 12-20 hours. On completion of the metered addition the I - 6 - 24 3 4 8 5 polymerisation temperature is maintained for a further 2 to 5 hours - with or without the addition of further polymerisation initiator - until conversion is virtually complete. The polymerisation is carried out at tempera-5 tures between 140 and 195°C, preferably at 160 to 190*0, the reaction being initiated at about 180 to 190°C. The temperature decreases in the course of the simultaneous copolymerisation, addition and condensation. In a preferred embodiment, illustrated by the 10 Examples, a mixture of inert solvents is introduced as initial charge and heated to the boil under reflux, the inert solvents having been selected in such a way that the reflux temperature is about 188°C. Following initiation of the copolymerisation and towards the end of the 15 metered addition time, the boiling temperature of the copolymer solution decreases to about 170°C to about 140°C. The metered addition is then followed by holding the temperature at 170°C to about 140°C until conversion is virtually complete and the desired solids content 20 (about 80% in the Examples) has been obtained. The polymerisation reaction is initiated with known polymerisation initiators. Suitable initiators are for example peroxides which decompose thermally into free radicals by a 1st order reaction. Initiator type and 25 amount are chosen in such a way that a very constant supply of free radicals is present at the polymerisation temperature during the metered addition phase. Preferred initiators for the polymerisation are: dialkyl peroxides, such as di-tert-butyl peroxide, 30 dicumyl peroxide; hydroperoxides, such as cumene hydroperoxide, tert-butyl hydroperoxide; peresters, such as tert-butyl perbenzoate, tert-butyl per-3,5,5-trimethyl-hexanoate, tert-butyl per-2-ethylhexanoate. The polymerisation initiators, in particular 35 tert-butyl per-2-ethylhexanoate, are preferably added in an amount of 2 to 6% by weight, based on the weight of monomer used. 24 3 4 - 7 - The molecular weight may be regulated using chain transfer agents. Examples are mercaptans, thioglycolic esters and chlorohydrocarbons, preference being given to dodecylmercaptan. 5 Suitable solvents for the solution polymerisation are customary inert paint solvents alone, preferably mixed, with boiling points of 150°C to 200°C, preferably 154°C to 200°C. The preferred organic solvents are those which later are also used in the ready-prepared coatings. 10 Examples of such solvents are: glycol ethers, such as ethylene glycol dimethyl ether; glycol ether esters, such as ethylglycol acetate, butylglycol acetate, 3-methoxy-n-butyl acetate, butyldiglycol acetate, methoxypropyl acetate; ethoxypropyl acetate, esters, such as butyl .15 acetate, isobutyl acetate, amyl acetate; and ketones, such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, aromatic hydrocarbons, such as xylene. Shellsol A (registered trade mark for aromatic hydrocarbon mixtures) and ali-20 phatic hydrocarbons can likewise be used cut with the abovementioned solvents. Preference is given to using a mixture of butyl glycol acetate, Shellsol A and ethoxypropyl acetate in a weight ratio of 1:2:2. Component a) for preparing the hydroxy1-25 containing copolymer solutions of the invention comprises glycidyl esters of a-alkylalkanemonocarboxylic acids and/or a,a-dialkylalkanemonocarboxylic acids. The glycidyl esters preferably have the empirical formula C13H2<,03 individually or together. 30 Since the glycidyl radical in the glycidyl ester of such a-alkylalkanemonocarboxylic acids and/or a,a-di-alkylalkanemonocarboxylic acids has the empirical formula C3H30, the a-alkylalkanemonocarboxylic acids and a,a-di-alkylalkanemonocarboxylic acids are isomer mixtures of 35 those monocarboxylic acids which contain a C10 chain. These acids are preferably very highly substituted at the a-disposed carbon atom and fully saturated; examples thereof are described in Deutsche Farbenzeitschrift, - 8 - 24348 No. 10/volume 16, page 435. Suitable hydroxyalkyl methacrylates having 1 to 6 carbon atoms in the hydroxyalkyl radical are hydroxy-methyl methacrylate/ 2-hydroxyethyl methacrylate/ 5 2-hydroxypropyl methacrylate, 4-butanediol monometh-acrylate, 5-pentanediol monomethacrylate, cyclohexanediol monomethacrylate and 4-dihydroxymethylcyclohexane monomethacrylate, alone or mixed, preference being given to using 2-hydroxyethyl methacrylate. 10 The solvent-free/ reactive, methoxy-functional polysiloxane component g with a narrow molecular weight distribution/ a low average molecular weight and a very low proportion of volatiles is Silicone Intermediate SY 231 from Wacker-Chemie GmbH, 8000 Munich 22. 15 Suitable carboxy-epoxy catalysts based on an alkali metal compound are all sodium, lithium, potassium, rubidium and caesium compounds - alone or mixed - which are soluble in the reaction mixture of methacrylic acid, monoglycidyl compound and vinyl compounds or at least 20 dissolve therein in the course of the metered addition and/or in the course of the reaction batch being maintained at the reaction temperature for the purpose of esterification by addition with simultaneous copolymerisation, although the alkali metal compound used 25 should be free of constituents which may have an unfavourable effect in the course of the copolymerisation of the addition product, which is an ester. It is possible to use for example the carbonates, bicarbonates, formates, iodides, bromides, fluorides and 30 hydroxides of the aforementioned alkali metals. On a factory scale it is best to use lithium hydroxide and potassium hydroxide, alone or mixed. Of these, potassium hydroxide is particularly advantageous on a factory scale on account of its low cost and excellent catalytic 35 properties. The alkali metal compound or hydroxide or mixture is advantageously dissolved in the methacrylic acid to be esterified. However, it is also possible first to convert the alkali metal compound, e.g.- alkali metal 24 3485 - 9 - hydroxide, carbonate or bicarbonate, and the methacrylic acid into the alkali metal salt thereof and then to dissolve the alkali metal salt of methacrylic acid as catalyst in the reaction mixture, if necessary by heating 5 in the course of the addition reaction. It is in general sufficient to add from about 0.001% by weight to about 0.5% by weight of alkali metal compound of the aforementioned kind, based on the weight of the ester-forming components, for the addition reac-10 tion. However, preference is given to an addition of about 0.001% by weight to about 0.3% by weight of alkali metal compound. The most preferred addition range extends from about 0.005% by weight to 0.1% by weight of an alkali 15 metal compound, in which case the alkali metal compounds used are very particularly advantageously potassium and lithium compounds. Special studies have shown that, if an alkali metal carboxy-epoxy catalyst, preferably an alkali metal 20 hydroxide, carbonate or bicarbonate, is used in preparing the copolymer solution, the coating compositions obtainable therefrom with polyisocyanates have special, unforeseeable properties. For instance, such two-component coating compositions have a longer pot life and 25 the coatings produced therefrom have a better ageing resistance as regards the loss in elasticity. The copolymer solutions according to the invention can be processed into clear or pigmented coating compositions. For this they are admixed in solvents with 30 a customary coatings polyisocyanate in the presence or absence of customary coatings additives and auxiliaries. Preferably, 60.0 to 80.0% by weight of the hydroxyl-containing copolymer B is admixed with 20 to 40% by weight of a difunctional and/or higher polyisocyanate as 35 component C; the percentages of components B and C always add up to 100%, The polyisocyanates C usable for crosslinking the copolymer B according to the invention are typical - 10 - 243485 coatings polyisocyanates. The proportion of polyisocyanate crosslinker is chosen in such a way that from 0.5 to 1.5 isocyanate groups are added per hydroxyl group of the hinder mixture. Excess isocyanate groups can react with moisture and contribute to the crosslinking. It is possible to use aliphatic, cycloaliphatic and aromatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexyl-methane, toluylene 2,4-diisocyanate, o-, m- and p-xylylene diisocyanate, 4,4'-diisocyanatodiphenyl-methane; blocked polyisocyanates, such as polyisocyanates blocked with acidic CH, NH or OH compounds; and also, for example, polyisocyanates with biuret, allophanate, urethane or isocyanurate groups. Examples of such polyisocyanates are a biuret formed from 3 mol of hexamethylene diisocyanate with 1 mol of water and having an NCO content of about 22% (corresponding to the commercial product Desmodur N BAYER AG, registered trade mark); a polyisocyanate with isocyanate groups, prepared by trimerisation of 3 mol of hexamethylene diisocyanate and having an NCO content of about 21.5% (corresponding to the commercial product Desmodur N 3390 BAYER AG, registered trade mark) or polyisocyanates with urethane groups, which are reaction products of 3 mol of toluylene diisocyanate and 1 mol of trimethylolpropane and have an NCO content of about 17.5% (corresponding to the commercial product Desmodur L BAYER AG, registered trade mark). Preference is given to using Desmodur N and Desmodur N 3390, BAYER AG, registered trade mark. As mentioned earlier, coating compositions prepared from components B and C can be transparent or pigmented. Transparent coating compositions find use for example as clear coatings in a two-layer coating composed of a pigment-containing basecoat and a transparent topcoat, applied wet-on-wet and subsequently cured either in air or in baking stoves. These clear coating 24 34 8 - 11 - compositions may, in addition to customary solvents for controlling the spray viscosity, also contain customary flow control agents and light stabilisers but also other customary coatings additives. 5 The aforementioned transparent or pigmented coat ing compositions may contain as further hardeners from 1 to 10% by weight of reactive amino resins customary for coatings. To prepare pigmented coating compositions, the 10 individual constituents are mixed with one another and conventionally homogenised or ground. A possible procedure is for example first to mix some of the copolymer solution with the pigments to be included and customary coatings auxiliaries and solvents and then to subject the 15 mixture to milling. The mill base is then completed with the remaining copolymer solution. The coating compositions obtained from the hydroxyl-containing copolymer solution according to the 20 invention have the considerable advantage of a high solids content coupled with a relatively low viscosity. Their flow-out properties are excellent and they lead to paint films of excellent gloss and outstanding build. The paint films obtained are very rapidly assemblyproof and 25 abhesive to adhesive tape, permitting for example multiple coating. The coating compositions obtainable from the copolymer solutions according to the invention are thus particularly suitable for use in the automotive industry for coating motor car bodies, but also suitable 30 in the refinishing sector for the rapid repair of, for example, accident damage. The copolymer solutions of the invention can be combined with amino resins to form binders which are suitable for baking finishes. Suitable amino resins are 35 the known reaction products of aldehydes, in particular formaldehyde, with substances carrying a plurality of amino or amido groups, for example melamine, urea, N,N'-ethyleneurea, dicyandiamide or benzoguanamine, - 12 - o 4 3 4 8 obtained by etherification with alcohols, in particular with n-butanol or isobutanol, in particular melamine-formaldehyde condensates, for example a melamine-formaldehyde condensate which has been etherified with 5 isobutanol in an average molar ratio of 1 melamine-6-formaldehyde to 3 mol of isobutanol. For instance, a baking clearcoat finish can consist of50to60% by weight of customary coatings solvents, of25to44% by weight of copolymers of the invention, 19 to 4 % by weight of an amino 10 resin, as well as customary baking finish additives. Embodiments of the invention will now be more particularly described by way of example. Preparation of copolymer solution A 4-1 three-necked flask equipped with a stirrer, 15 a contact thermometer, a spherical condenser with a reflux trap for methanol and any other elimination products, and 2 dropping funnels is charged with constituent I in accordance with the quantitative data given below in the table and the contents are heated with 20 stirring and under switched-on reflux cooling to about 180 to 190°C. Constituent II (monomer mixture and KOH as carboxy-epoxy catalyst and optionally a chain transfer agent) and constituent III (solvent-initiator mixture) are metered in continuously from dropping funnels 1 and 25 2 in the course of 16 hours. The temperature decreases from 188°C towards the end of the addition time to about 160 to about 165°C. On completion of the metered addition a temperature of about 160 to 167°C is maintained for 3 hours, during which if necessary further polymerisation 30 initiator is added after one hour, so that conversion is virtually complete. - 13 - 943485 Table (weights in grams) 10 15 20 25 30 35 Copolymer 1 Copolymer 2 Copolymer 3 Constituent I Butvlalvcol acetate 100 100 100 EthoxvDroDvl acetate 160 160 160 Mixture of aromatic hydrocarbons (Shellsol A, regis tered trade mark) 200 200 200 Glycidyl ester (Cardura E 10, regis tered trade mark) 400 400 400 II Methacrvlic acid 182 182 182 2-Hydroxyethyl methacrvlate 420 478 536 Stvrene 478 360 247 Polypropylene glycol monomethacrvlate* 20 20 21 Methvl methacrvlate 200 160 114 Potassium hvdroxide 0.1 0.1 0.1 Silicone Intermediate SV 231 300 400 500 III EthoxvoroDvl acetate 40 40 40 tert-Butyl Der-2-ethvlhexanoate 80 80 80 Parameters: Solids content (%): 80 80 80 Viscosity*' DIN 4 cup after dilution with butyl acetate to 60% bv weiaht solids 60-90 sec. 81-86 sec. 70-100 sec. Acid number*5 (based on resin sol ids): 16.4-19.3 18.9-20 20.6 OH number*' (based on resin solids): 125-170 156 150 Average molecular weight from 350 to 387 40 *5 Range of variation obtained in numerous repeats of the reaction. - 14 - 24 3 4 8 5 First studies have shown that the copolymer solution can be prepared under the stated conditions even in the absence of carboxy-epoxy catalysts. Preparation of clear coating from copolymer solution 1 5 In a clean, dry vessel 800 g of butyl acetate, 850 g of xylene, 1050 g of a mixture of aromatic hydrocarbons (Shellsol A trade mark), 150 g of light stabiliser (trade name Tinuvin® 1130), 100 g of light stabiliser (trade name Tinuvin® 292), 50 g of 5% strength 10 dibutyltin dilaurate solution in xylene as accelerator and 200 g of flow-control agent (trade name Byk® 300 10% strength in xylene) are thoroughly mixed. Then 6800 g of copolymer solution 1 (previously adjusted from 80% by weight solids to 75% by weight solids with butyl acetate) 15 are added and thoroughly mixed in. Then 3000 g of the coatings polyisocyanate Desmodur® N 3390, 80% solution in 1:1 xylene/butyl acetate, are added to the batch and thoroughly mixed in, and the viscosity of the mixture is immediately determined in a DIN 4 cup. The batch is 20 diluted with 1:1 Shellsol® A/butyl acetate to a spray application viscosity corresponding to an efflux time of 21 seconds. The solids content of the aforementioned clear coating is 54.8% by weight. This represents a distinct 25 improvement over the prior art solids content of only 50.2% by weight. Further tests of the clear coating have shown that it has improved performance characteristics. Applied to test panels and, after flash-off, heated at 80°C for 45 minutes, it produced a pendulum hardness of 30 120 seconds and heated at 130°C for 30 minutes after flash-off it produced a pendulum hardness of 157 seconds. The measurement was carried out after standing for one hour for the purpose of cooling. Preparation of a white coating from copolymer solution 1: 35 In a clean, dry vessel 550 g of Shellsol® A, 665 g of butyl acetate 98/100, 200 g of antisettling agent consisting of Bentone® 38.10% strength in xylene and 4% Anti-Terra® U, 50 g of dibutyltin dilaurate 1% strength by 24 34 8 5 - 15 - weight in xylene, 2500 g of copolymer solution 1 (diluted as indicated earlier to a solids content of 75% by weight) and 375 g of wetting agent (trade name Byk® 160 30% strength) are thoroughly mixed, and 2900 g of the 5 white pigment titanium dioxide 2160 are gradually added with stirring and the mixture is then bead milled for 30 minutes with a bead ratio of 1:1. The batch are then admixed with 1500 g of copolymer solution 1, previously adjusted to 75% by weight solids, 200 g of flow control 10 agent (Byk® 344 10% strength by weight in xylene), 300 g of deaerating agent (Byketol® OK) and 760 g of n-butyl acetate and thoroughly mixed. To this batch are added 1800 g of dilution Bd 1316 as solvent followed with thorough stirring by 1800 g of the coatings polyiso-15 cyanate Desmodur®N 3390 90% strength. The solids content of the aforementioned white coating is 63% by weight. This fact reveals that the coatings which contain the copolymer solution according to the invention can be applied within a shorter period (e.g. omission of spray-20 ing operations) and that the paint film produced nonetheless has satisfactory performance characteristics and, by virtue of the spraying being shortened, less organic solvent is emitted into the environment. The aforementioned dilution Bd 1316 is obtained by mixing 2500 g of 25 ethoxypropyl acetate, 2500 g of n-butyl acetate, 500 g of butoxyl (= 3-methoxy-l-butyl acetate), 2500 g of xylene and 2000 g of Shellsol® A. The pot life of the aforementioned white coating, measured as the DIN 4 cup efflux time, was: 30 measured immediately following preparation 21 seconds after 2 hours 27 " after 4 hours 39 " after 6 hours 58 " 35 after 8 hours 120 " Steel panels coated with commercial primer were overcoated after one day with the aforementioned white coating and cured at 80°C for 60 minutes. "The properties Zk 3 4 - 16 - were measured after 24 hours: 24 /m 44 pm 93% prxmer coating gloss 60° 5 Konig pendulum hardness Buchholz hardness 10 Erichsen indentation adhesion (cross hatch test) Gt 0 108 87 measured to DIN 67530 and ISO 2813 measured to DIN 53157 or ISO 1522 measured to DIN 53153 or ISO 2815 7.5 mm measured to DIN 53156 or ISO 1520 measured to DIN 53151 or ISO 2409 resistance 15 test 5' xylene pass 5' four-star petrol unleaded pass Resistance tests with xylene and unleaded four-star petrol 20 A cotton wool swab soaked with xylene or unleaded four-star petrol was placed on the baked film of the white coating in the covered state and left for 5 minutes. After the cotton wool swab had been removed and the test liquid wiped away, the dry tested film was 25 assessed. For a film to pass, as in the present case, it must not show any changes. Evaluation of aforementioned test results: Despite the high solids content of the in-test coating, the measured values show that the gloss, the 30 Konig pendulum hardness, the Buchholz hardness, the Erichsen indentation, the cross hatch and the petrol resistance tests all produced values which correspond to those of very good commercial products, which, however, have the disadvantage that the coatings have only a lower 35 solids content. Any person skilled in the art knows that as the solids content of a coating increases it is very difficult to achieve the required high guality features at all, so that the test results demonstrate surprising - 17 - 24 3 4 8 5 properties. Preparation of a clear coating from copolymer solution 2 In a clean, dry vessel 800 g of n-butyl acetate, 850 g of xylene, 1050 g of a mixture of aromatic hydro-5 carbons (Shellsol A trade mark), 150 g of light stabiliser (trade name Tinuvin® 1130), 100 g of light stabiliser (trade name Tinuvin® 292), 50 g of a 5% strength dibutyltin dilaurate solution in xylene as accelerator and 200 g of flow control agent (trade name 10 Byk® 300 10% strength in xylene) are thoroughly mixed. Then 6800 g of copolymer solution 2 (previously adjusted from 80% by weight solids to 75% by weight solids with butyl acetate) are added and thoroughly mixed in. Then 3000 g of coatings polyisocyanate/Desmodur® N 3390 dis-15 solved in 80% strength in 1:1 xylene/butyl acetate are added to the batch and thoroughly mixed in and the viscosity is determined at once in a DIN 4 cup. By diluting with a 1:1 Shellsol® A/butyl acetate mixture the batch is adjusted to a spray application viscosity 20 corresponding to an efflux time of 21 seconds. The solids content of the aforementioned clear coating is 54.7% by weight. This represents a distinct improvement over the prior art solids content of only 50.2% by weight. Further tests on the clear coating have 25 shown that it has improved performance characteristics. Preparation of a white coating from copolymer solution 2: In a clean, dry vessel 550 g of Shellsol® A, 665 g of n-butyl acetate, 200 g of an antisettling agent comprising Bentone® 38 10% strength in xylene and 4% of 30 Anti Terra® U, 50 g of dibutyltin dilaurate 1% strength by weight in xylene, 2500 g of copolymer solution 2 (diluted to a solids content of 75% by weight as indicated above) and 375 g of a wetting agent (trade name Byk® 160 30% strength) are thoroughly mixed, and 2900 g of the white 35 pigment titanium dioxide 2160 are gradually added with stirring, and the mixture is introduced into a bead mill and bead milled for 30 minutes with a bead ratio of 1:1. The batch is then admixed with 1500 g ~ of copolymer - 18 - 24 3 485 solution 2 (adjusted to 75% solids), 200 g of a flow control agent (Byk® 344 10% strength by weight in xylene), 300 g of a deaerating agent (Byketol* OK) and 760 g of butyl acetate and thoroughly mixed. To this batch are 5 added 1800 g of dilution Bd 1316 as solvent followed with thorough stirring by 1800 g of coating polyisocyanate Desmodur® N 3390 90% strength. The solids content of the aforementioned white coating is 63.5% by weight. This fact shows that coatings which contain the copolymer 10 solution of the invention can be applied within a shorter time (for example through omission of spraying operations) and that the paint film produced nonetheless has satisfactory performance characteristics and less organic solvent is emitted into the environment by virtue of the 15 shortening of the spraying operation. The pot life of the aforementioned white coating, measured as efflux time from the DIN 4 cup, was: measured immediately following preparation 21 seconds 20 after 2 hours 33 " after 4 hours 54 " after 6 hours 120 " Steel panels coated with commercial primer were - overcoated after one day with the aforementioned white 25 coating and cured at 80°C for 60 minutes. The properties were measured after 24 hours: primer 22-26 pm coating 44-51 fim gloss 60° 93% measured to DIN 67530 30 or ISO 2813 Konig pendulum hardness 114^ measured to DIN 53157 or ISO 1522 Buchholz hardness 87 measured to DIN 53153 or ISO 2815 35 Erichsen indentation 6.8 mm measured to DIN 53156 or ISO 1520 adhesion (cross hatch test) Gt 0 measured to DIN 53151 or ISO 2409 - 19 - 243485 resistance test 5' xylene pass 5' four-star petrol unleaded pass 5 The aforementioned test results likewise show the surprising properties of the films compared from the white coating based on copolymer solution 2, as demonstrated earlier at length with the films of white coating based on copolymer solution 1. 10 Preparation of an amino resin clear coating from copolymer solution 1: In a clean, dry vessel 400 g of aromatic hydrocarbons (Shellsol A trade mark), 35 g of light stabiliser (trade name Tinuvin® 1130), 35 g of light stabiliser 15 (trade name Tinuvin® R 292) and 200 g of a flow control agent (trade name Byk® 300 10% strength in xylene) are thoroughly mixed. Then 5600 g of copolymer solution 1 (previously adjusted from 80% by weight solids to 75% by weight solids with butyl acetate) are added and thorough-20 ly mixed in. Then 373 g of melamine resin BE 683 are added to the batch and thoroughly mixed in and the viscosity is determined at once in a DIN 4 cup. By diluting with a mixture of 30 g of xylene, 20 g of n-butanol and 35 g of Solvesso® 150 and 5 g of ethoxy-25 propyl acetate the batch is adjusted to a spray application viscosity corresponding to an efflux time of 21 seconds. The solids content of the aforementioned clear coating is 43.6% by weight. This represents a distinct 30 improvement over the prior art solids content of only 40% by weight. Further tests on the clear coating have shown that it has improved performance characteristics. Applied to test panels and, after drying, baked at 130°C for 30 minutes, the clear coating resulted in a pendulum 35 hardness of 128 seconds. Preparation of an amino resin clear coating from copolymer solution 1: - 20 - 243485 In a clean, dry vessel 400 g of aromatic hydrocarbons (Shellsol A trade mark), 35 g of light stabiliser (trade name Tinuvin® 1130), 35 g of light stabiliser (trade name Tinuvin® R 292) and 200 g of a flow control 5 agent (trade name Byk® 300 10% strength in xylene) are thoroughly mixed. Then 6530 g of copolymer solution 1 (previously adjusted from 80% by weight solids to 75% by weight solids with butyl acetate) are added and thoroughly mixed in. Then 280 g of melamine resin BE 683 are 10 added to the batch and thoroughly mixed in and the viscosity is determined at once in a DIN 4 cup. By diluting with a mixture of 30 g of xylene, 20 g of n-butanol and 35 g of Solvesso® 150 and 5 g of ethoxy-propyl acetate the batch is adjusted to the spray 15 viscosity corresponding to an efflux time of 21 seconds. The solids content of the aforementioned clear coating is 43.5% by weight. This represents a distinct improvement over the prior art solids content of only 40% by weight. Further tests on the clear coating have shown 20 that it has improved performance characteristics. Applied to test panels and, after drying, baked at 130°C for 30 minutes, the clear coating resulted in a pendulum hardness of 12 seconds. The description, the examples, the coatings and 25 the experimentally determined data all show that the above-stated objects of the invention are indeed achieved. The preparation of the copolymer solutions and of the coatings involved the use of commercial products 30 which will now be more particularly described: Shellsol® A starts to boil at 166°C and has an aromatics content of 98% by volume. Tinuvin® 1130 is a liquid UV absorber based on a hydroxyphenylbenzotriazole derivative. It is the reaction 35 product of the following 2 components and has an average molecular weight of M^, > 600: - 21 - 24 3 4 8 5 HO r ^ N- N ch2chzcooch; HO (CH^CH^O)^ n = 6.7 Methyl 3-[3-(2H-benzo-tri azol-2-yl)-5-tert-butyl-4-hydroxyphenyl]propionate Polyethylene glycol 300 TINUVIN 1130 10 15 20 25 30 Tinuvin® 292 is a liquid light stabiliser, developed for the light stabilisation of industrial coatings. Tinuvin® 292 is a member of the class of the sterically hindered amines (HALS). It has the advantage of not being sensitive to acid-catalysed systems which are used as automotive refinishes with low baking temperatures. BYK®-300 is an additive for increasing the scratch and mar resistance and it is based on a 50% strength solution of a specific, coating-compatible polysiloxane copolymer. It is manufactured by Byk-Chemie GmbH in D-4230 Wesel. BYK®-344 is an additive for increasing the scratch and mar resistance, and it is a 50% strength solution of a specific, modified, coating-compatible siloxane copolymer. Density at 20°C (DIN 51757) Refractive index (DIN 53491) Nonvolatiles (ASTM D1644B) Solvent Flashpoint (DIN/ISO 3679) Appearance 0.93-0.95 g/cm3 1.463-1.468 48-50% 4:1 xylene/isobutanol 23°C clear or slightly cloudy liquid Manufacturer: BYK-Chemie GmbH BYKETOL*-OK is a flow control additive based on a mixture of high boiling aromatics, ketones and esters. Density at 20°C (DIN 51757) 0.86-0.87 g/cm3 Refractive index (DIN 53491) 1.468-1.474 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> - 22 - 243485 Flashpoint (DIN/ISO 3679) Appearance 42°C clear or slightly cloudy liquid Manufacturer: BYK-Chemie GmbH Silicone Intermediate SY 231 is a solvent-free, reactive, methoxy-functional polysiloxane having a narrow molecular weight distribution, a low average molecular weight and a very low volatiles content. Silicone Intermediate SY 231 is a clear, slightly yellowish liquid having an alkoxy equivalent of 222, a total silicone content (all methoxy groups replaced by Si-O-Si bonds) of 89% by weight, a viscosity at 25°C of 100-150 mm2/s, a density at 25°C of 1.14 g/ml, a refractive index at 25°C of 1.500-1.505, and a volatiles content (5 g/1 h/150°C) of 2% by weight. Manufacturer: Wacker-Chemie GmbH, 8000 Munich 22. BE 683 A is an n-butylated melamine resin having a relatively high solids content of 75% ± 2, dissolved in n-butanol. Its acid number (mg of KOH/g) is 0.1 max. The viscosity (poise at 25°C) is between 30 and 60. The white spirit tolerance (ml/5 g) is between 28 and 60. Its viscosity allows transport in tank vessels. It has a wide compatibility range, a high reactivity and good flow properties. Manufacturer: BIP Chemicals Ltd. Popes Lane Oldbury, Warley West Midlands B69 4PD 243^ 5 23 WHAT WE CLAIM IS:-

1. Copolymer solution containing inert organic solvents and copolymers comprising: A) 15.0-50.0.% by weight of inert organic solvents customary in the paints industry, B) 50.0-85.0% by weight of hydroxyl-containing copolymers obtained by simultaneous addition, condensation and polymerisation in inert organic solvents (which solvents are the same as or different to those in Part A) or mixtures 15 thereof with a boiling range between 160°C and 200°C by heating under reflux in the presence of polymerisation initiators, optional chain transfer agents, and optionally carboxy-epoxy catalysts, of a) 10 to 30% by weight of glycidyl esters of a-alkyl-20 alkanemonocarboxylic acids and/or a,a-dialkylalkane-monocarboxylic acids, b) 5 to 12% by weight of methacrylic acid, c) 10 to 27% by weight of hydroxyalkyl methacrylate 25 having 1 to 6 carbon atoms in the hydroxylalkyl radical, d) 10 to 38% by weight of styrene, e) 1 to 5% by weight of polypropylene glycol mono methacrylate having an average 30 molecular weight of 350 to 387, f) 3 to 20% by weight of alkyl methacrylate having 1 to 8 carbon atoms in the alkyl radical, and g) 9 to 20% by weight of solvent-free, reactive, 35 methoxy-functional polysiloxane, the percentages of components a, b, c, d, e, f and g always adding up to 100% b^" weight. ' "27 Apr:"°4 10 - 24 - 245485

2. Copolymer solution according to Claim 1, charac terised in that component B comprises a copolymer prepared from mixtures consisting of a) 17 to 25% by weight of glycidyl esters of a-alkylalkanemonocarboxylic acids and/or a,a-dialkylalkane-monocarboxylic acids, b) 7 to 12% by weight of methacrylic acid, c) 15 to 26% by weight of 2-hydroxyethyl methacrylate, d) 17 to 28% by weight of styrene, e) 1 to 3% by weight of polypropylene glycol mono methacrylate having an average molecular weight of 350 to 387, *>■ 5 to 15% by weight of methyl methacrylate, and g) 12 to 17% by weight of solvent-free, reactive, 15 methoxy-functional polysiloxane, the percentages of components a, b, c, d, e, f and g always adding up to 100% by weight. 20

3. Copolymer solution according to Claim 1, characterised in that component B comprises a copolymer prepared from a mixture consisting of: a) 18 to 24% by weight of glycidyl esters of a-alkyl alkanemonocarboxylic acids 25 and/or a,a-dialkylalkane- monocarboxylic acids, b) 6 to 12% by weight of methacrylic acid, c) 17 to 22% by weight of hydroxyalkyl methacrylate having 1 to 6 carbon atoms in 30 the hydroxyalkyl radical, d) 20 to 28% by weight of styrene, e) 1 to 3% by weight of polypropylene glycol mono methacrylate having an average molecular weight of 350 to 387, 35 f) 8 to 12% by weight of methyl methacrylate, and g) 12 to 27% by weight of solvent-free, reactive, methoxy-functional polysiloxane, the percentages of components a, . i t ; V ^ 23 NOVf993 : 'V.V _ . W /. 10 - 25 - 2*3485 b, c, d, e, £ and g always adding up to 100% by weight.

4. Copolymer solution according to Claim 1, characterised in that component B comprises a copolymer prepared from mixtures consisting of: a) 8 to 22% by weight of glycidyl esters of a-alkyl- alkanemonocarboxylic acids and/or a,a-dialkylalkane-monocarboxylic acids. b) 7 to 10% by weight of methacrylic acid, c) 19 to 22% by weight of 2-hydroxyethyl methacrylate, d) 20 to 28% by weight of styrene, e). 1 to 3% by weight of polypropylene glycol mono methacrylate having an average molecular weight of 350 to 387, f) 9 to 11% by weight of methyl methacrylate, and g) 13 to 17% by weight of solvent-free, reactive, 15 methoxy-functional polysiloxane, the percentages of components a, 20 b, c, d, e, f and g always adding up to 100% by weight.

5. Copolymer solution according to any one of Claims 1 to 4, characterised in that, after its preparation, it consists of A) 15.0-25.% by weight, of customary inert organic paint solvents and B) 75.0-85.0% by weight of hydroxyl-containing copolymers.

6. A copolymer solution according to claim 5 wherein the amount of said customary inert organic paint solvents is in the range 15 to 20% by weight. 30

7 . Copolymer solution according to any one of Claims 1 to 6 , characterised in that as carboxy-epoxy catalyst there is present 0.001% by weight to 0.5% by weight of at least one alkali metal compound, based on the weight of the ester-forming components. 35

8. Two-component coatings containing as binder a copolymer solution according to any one of Claims 1 to 7 and as hardener a difunctional or higher polyisocyanate. ; \ t'i / x . *- 0 ■>-. s x - 23 NOV 1993 ; ft ,v' "... _ 17 JAN 1994 - !2"4 J 4 8 5 ..

9. Two-component coatings according to claim 8 containing 60 to 80% by weight of copolymer solution as binder and 20 to 40% by weight of di- and/or higher polyisocyanate as hardener.

10 Two-component coatings according to Claim 3 or 9 containing 1 to 10% by weight of reactive amino resins as additional hardeners.

11 . Baking finishes containing as .binder a copolymer solution according to any one of Claims 1 to 7 and as hardener at least one reactive amino resin.

12. Baking finishes according to claim 11 containing 60 to 90% by weight of copolymer solution as binder and 10 to 40% by weight of reactive amino resin. 1? .

Process for preparing the hydroxyl-containing copolymer solutions according to any one of Claims 1 to 7 , characterised by heating a mixture consisting of component A and the monomers of component B, the boiling point of component A being such that, after the reaction has ended, the copolymers are present in component A with the desired solids content, as initial charge into which the necessary monomers a, b, c, d, e, f and component g, polymerisation initiators, optional chain transfer agents, and optionally carboxy-epoxy catalysts are gradually introduced at the polymerisation temperature at the rate of the polymerisation and the simultaneous addition and condensation and on completion of the metered addition,if necessary, maintained at the polymerisation temperature until the reaction has ended.

14 . Process according to Claim 13 characterised in that component A has a boiling range between 180°C and 200°C and is kept as initial charge at the reflux temperature and the metered addition is effected at a uniform rate over 12 to 20 hours and on completion of the metered addition the batch is maintained at the reflux temperature until the copolymerisation has ended, although the reflux temperature may drop to about 140°C.

15. Process according to either of Claims 13 and-14, characterised in that component A is used in an amount of !* 17 .IANl994m., 27 15 to 25% by weight.

16. A process according to claim 15 characterised in that component A is used in an amount of 15 to 20% by weight.

17. Process according to any one of claims 13 and 16, characterised in that as carboxy-epoxy catalyst there is used 0.001% by weight to 0.5% by weight of at least one alkali metal compound, based on the weight of the ester-forming components.

18. A copolymer solution as claimed in claim 1 and substantially as hereinbefore described with reference to any one of the foregoing Examples. SYNTH0P0L CHEMIE DR. RER. POL KOCH GmbH & CO. KG by their authorised agents P.L. BERRY & ASSOCIATES </div>