DE2110054B2 - Adhesive coating compounds for metals based on acrylate - Google Patents

Description

The invention relates to coating compositions for metals which consist of mixtures of an externally crosslinkable acrylic polymer and a crosslinking acrylic polymer. The coating compositions are ^{baked on metals at temperatures above 120 °} C. to form highly elastic and, at the same time, hard, weather-resistant coatings

From the German Auslegeschrift 1 244 410 it is known to crosslinkable polymers with the aid of alkoxymethyl isocyanates produce by inter alia polymerization products with a molecular weight over 600, which contain Zerewitinoff-active hydrogen atoms in the molecule, with alkoxymethyl isocyanates to react. In this way

ίο can include crosslinkable lacquer coating agents can be obtained. The products according to the method of this document have admittedly compared to others known coating agents have significant advantages, but films made therefrom are more optimal in terms of Weather resistance with simultaneous high elasticity and hardness not yet satisfactory.

It is further from British patent specification 1159859 known to mix coating compositions for paints from several components by using at least one

ao hydroxyl-containing polyacrylate, at least one N-alkoxymethyl urethane and optionally at least a melamine formaldehyde and / or urea formaldehyde resin used. Here, N-alkoxymethyl urethanes are converted into reaction products Polyalcohols with Cj-Cuj-alkoxymethyl isocyanates Understood. As polyalcohols, low molecular weight polyalcohols, such as. B. glycerine, in addition, polyethers, polyesters and also polyurethanes are described.

These combinations have inadequate weather resistance, especially in the case of metal effect coatings leaves a lot to be desired. Metal effect coatings are particularly common in automobiles exposed to strong weather conditions.

The object of the present invention is therefore to provide coating compositions for metals, in particular for metal strip coatings and metallic paints, the cured films of which have good weather resistance have a good surface hardness with high elasticity at the same time.

The object is achieved by using mixtures of an externally crosslinkable as coating compositions Acrylic polymer and a crosslinking acrylic polymer are used. A sharing elasticizing or crosslinking components, for example from the substance class of Polyalcohols, polyethers, polyesters, polyurethanes, polyacetals, urea, phenol or melamine-formaldehyde resins is no longer required.

The invention thus provides firmly adhering coating compositions for metals based on acrylate, consisting from a mixture of

A. 10 to 90 parts by weight of an externally crosslinkable copolymer with an average molecular weight 5000 to 20,000, which has been prepared by interpolymerization of

a) 10 to 90 percent by weight of at least one ester of acrylic and / or methacrylic acid with 1 to 20 carbon atoms in the alcohol component with

b) 0 to 50 percent by weight of at least one hydroxyl-containing, olefinically unsaturated, copolymerizable monomers,

c) 0 to 40 percent by weight of at least one unsaturated carboxylic acid,

d) 0 to 40 percent by weight of acrylic and / or methacrylic acid amide or at least one N-substituted

3 4

tuierten derivative of acrylic and / or methacrylic 2-hydroxypropyl methacrylate, butanediol-l, 4-mo-

saareamids, noacrylate or their mixtures,

e) 0 to 50 percent by weight of at least one mono- b) 95 to 20 percent by weight, preferably 80 to

mers from the group styrene, α-methylstyrene, 60 percent by weight methacrylate, ethyl acrylate

Acrylonitrile, vinyl acetate, vinyl propionate, vinyl 5 or 2-ethylhexyl acrylate or butyl acrylate or

alkyl ethers with 1 to 8 carbon atoms in their mixtures and

Alkyl radical, methacrylonitrile, allyl acetate, vinyl c) 0 to 5 percent by weight, preferably 0 to 3 Ge

chloride or vinylidene chloride, where the sum is weight percent acrylic acid, methacrylic acid,
the percentage is 100 and the only one

Combination of a) and e) is excluded, and io where the sum of the percentages is 100 and

the polymer with 0.1 to 50 percent by weight,

B. 10 to 90 parts by weight of a crosslinking with A, preferably 5 to 30 percent by weight methoxymethyl

and at room temperature soft to rubber isocyanate, based on the copolymer, reacted

elastic copolymer based on acrylate has been with.

an average molecular weight of 1000 to 5000, which 15 are specifically among the monomers in the

has been made from groups a) to e) are named for component A,

to understand:

a) 5 to 80 percent by weight of at least one Hy-monomer of group a): Aliphatic or cyclodroxyl-containing monomers, aliphatic esters of acrylic or methacrylic acid with

b) 20 to 95 percent by weight of at least one 20 1 to 20, preferably 1 to 8 carbon atoms in Esters of acrylic or methacrylic acid with 1 bis the alcohol component. Examples are 20 carbon atoms in the alcohol component, methyl acrylate, ethyl acrylate, n- or isopropyl acrylate,

c) 0 to 5 percent by weight of at least one free butyl acrylate, isooctyl acrylate, dodecyl acrylate, octaft, / 8-unsaturated Carboxylic acid with 3 to 5 C-atom decyl acrylate, cyclohexyl acrylate and the corresponding 25 the methacrylic acid ester.

d) 0 to 50 percent by weight of at least one non-monomer of group b) are hydroxyl groups functional monomers and containing, copolymerizable monomers, such as hy-

e) 0 to 15 percent by weight of at least one counter-hydroxyalkyl ester of the acrylic, methacrylic, maleic, if necessary N-mono-alkylated acrylic or meth, fumaric or itaconic acid with 2 to 8 carbon acrylic acid amides, where the sum of the percent atoms in the alkyl radical, preferably with 2 to 4 carbon contents 100 and the copolymer B atoms in the alkyl radical. For example: with 0.1 to 50 percent by weight, based on the hydroxyethyl acrylate, hydroxypropyl acrylate, Hy-total mass, an alkoxymethyl isocyanate um- droxybutyl acrylate and the corresponding methet has been. acrylic acid esters.

35 Group b) also includes allyl or vinyl

Particularly favorable results are obtained, ethereal polyhydric alcohols containing 2 to 12 carbons the mixture of components A and B atoms of matter. The following alcohols are exemplary as defined above from the following: glycol, glycerine, trimethylolpropane, Monomers are built up: erythritol, pentaerythritol, etc.

40 The allyl or vinyl ethers still have at least

Component A: Copolymer of a free hydroxyl group, such as trimethylolpropane

a) 10 to 90 percent by weight, preferably 10 to monoallyl ether or glycerol monovinyl ether.

50 percent by weight methyl acrylate, ethyl acrylate, the hydroxyalkyl esters are preferably the

Butyl acrylate, 2-ethylhexyl acrylate or methyl acrylic and methacrylic acid with 2 to 4 carbon

methacrylate or mixtures thereof, 45 atoms used in the alkyl radical.

b) 0 to 50 percent by weight, preferably 5 to Under monomers of group c) % , / S-mono-30 percent by weight of 2-hydroxyethyl acrylate, 2-hydroxy-olefinically unsaturated carboxylic acids with 3 to 5 hydroxyethyl methacrylate, 2-hydroxypropyl methylene atoms are understood . The following may be mentioned by name: acrylate, 2-hydroxypropyl acrylate, butanediol acrylic acid, methacrylic acid, crotonic acid, maleic 1,4-monoacrylate or mixtures thereof, 5 ° acid, fumaric acid or itaconic acid, are preferred

c) 0 to 40 percent by weight, preferably 0 to acrylic and methacrylic acid.

15 percent by weight of (meth) acrylic acid or its monomers of group d) are acrylic or

Mixtures, methacrylic acid amides or N-substituted derivatives,

d) 0 to 40 percent by weight, preferably 0 to such as N-alkyl acrylamides or methacrylamides with 1 to 15 percent by weight (meth) acrylic acid amide or 55 8 carbon atoms in the alkyl radical, N-methylol or their mixtures, N-methylol ethers of acrylic and methacrylic acid

e) 0 to 50 percent by weight, preferably 20 to amide, Mannich bases of acrylic and methacrylic acid-50 Percent by weight of styrene or α-methylstyrene amides or diacetone acrylamide or diacetone meth- or their mixtures, acrylamide. Derivatives of acrylic or methacrylic acid

60 amids are used if they are

where the sum of the percentages is 100 and polymerization does not cause crosslinking,

the sole combination of a) and e) preferably acrylic and methacrylic acid

is closed. amide used.

Group e) monomers are styrene, a-methyl-

Component B: mixed polymer of 65 styrene, acrylonitrile, vinyl acetate, vinyl propionate, vinyl

a) 5 to 80 percent by weight, preferably 20 to alkyl ethers with 1 to 8 carbon atoms in the alkyl radical,

40 percent by weight of 2-hydroxyethyl methacrylate, methacrylic acid nitrile, allyl acetate, vinyl chloride or

2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, vinylidene chloride.

S. 6th

Preference is given to styrene and α-methylstyrene. The choice of mixing temperature depends on this

used. whether it is mixed in substance or in solution. Here

The copolymerization of the monomers of the compo- must be observed that temperatures of about;

NenteA is carried out according to known, customary processes from 110 to over 130 ° C only for a short time

the emulsion, dispersion, solution or sub- 5 may, since with prolonged thermal stress Ver

Punch polymerization, as can occur, for example, in German wetting.

see patent application P 19 65 740.0, in which 90 to 10 parts by weight of the soft «

lying application or in methods of the organic elastic components B with 10 to 90 weight

see Chemie, Houben-Weyl, 4th edition, share the brittle and hard component A ge

1961, vol. 14/1. io mixes.

Monomers for the Production of the Copolymer The coating compositions according to the invention consist

(Component B): from two components, from a soft, elastic

The monomers of group a) are exemplified and consist of a hard and brittle component

Understood wisely: Hydroxymethylnorbornene, Dihy- The elasticity of a resin is due to its mobility

droxymeth>; uorbornene, phenylallyl alcohol, hydroxy- 15 of the molecular chains. Have brittle resins

alkyl esters of acrylic or methacrylic acid, such as acrylic- little mobile chains, which are usually through secondary

acid or methacrylic acid hydroxyethyl ester, - / S-hydrolence forces and crystalline areas in their movement

Droxypropylester, - / Wiydroxyburylester, whereby the hy- lichJceit are hindered. The soft elasticises

hydroxyl group on a primary or secondary carbon component with a molecular weight of 1000 to 500C

substance atom can be bound; Hydroxyalkyl esters of the 20 with their flexible molecular chains carry N-alkoxy

Fumaric or maleic acid, such as fumaric acid-uihydroxymethyl urethane groups and reacts when stoving

ethyl ester, fumaric acid monohydroxyethyl ester, gangway with the NH or OH groups of the brittle and

marsic acid-hydroxyethyl-ethyl ester. Trimethylolpropane hard component with a molecular weight of 5000 to

monoallyl ether, glycol monovinyl ether. 20 000. After the burn-in process, there is a network

The monomers of group b) include accessories whose meshes consist of two different types

for example: acrylic acid or methacrylic acid methyl segments is built up from relatively short-chain

esters, ethyl esters, cyclohexyesters, branched and non-elasticizing segments and from longer-chain,

branched esters of propanol, butanol, octanol. brittle parts. The one after the burn-in process

The monomers of group c) include highly crosslinked coatings with this

For example: Λ, / 9-unsaturated carboxylic acids with 3 to 30 segment-like structure surprisingly show

5 carbon atoms, such as acrylic acid or methacrylic acid, a high surface hardness with at the same time excellent

Maleic acid, fumaric acid, itaconic acid. excellent elasticity. It is also possible to do the hard,

Examples of monomers of group d) include brittle component A first in the alkoxymethyl

named: Λ-methyl styrene, vinyl toluene, acrylonitrile, vinyl urethane to be treated with an alkoxymethyl isocyanate

acetate, methacrylonitrile, -chloroacrylonitrile, vinylidene 35 lead to then with the free OH resp.

Chloride. NH groups of a soft elasticizing composite

Monomers of group e) include: allowing acrylent B to react during the stoving process,

amide or methacrylamide, N-methylacrylamide, N-Me- The segment-like structure also remains

keep ethyl methacrylamide, N-ethyl acrylamide, N-ethyl meth-. But this path does not have the same meaning

acrylamide. 40 like the one according to the invention, since it is technically simpler

The copolymerization of the monomers of the composite is to be realized, the soft elasticizing component B is carried out according to known, customary processes to convert component B into the alkoxymethyl urethane, emulsion, dispersion, solution or excellent application-specific bulk polymerization, such as, for example, in the shafts of the coating compositions according to the invention, the German patent application P 20 05 691.1, in which the cured films are determined beforehand lying registration or in methods of the organic neither achieved if the component A alone as see chemistry, Houben-Weyl, 4th edition, binder is used, nor component B 1961, vol. 14/1. for yourself. Neither can these properties

As alkoxymethyl isocyanates, C ₁ -C ₁₈ -Alk- are found on films of a binder which

oxymethyl isocyanates of any kind, especially methoxy 50 through simultaneous copolymerization of all mono-

methyl isocyanate, ethoxymethyl isocyanate, isopropoxymers, which are found in component A and component B

methylibocyanate, butoxymethyl isocyanate, hexoxyme are obtained. These facts that made up

ethyl isocyanate, in consideration, preferably methoxymides, can be seen from the comparative experiments of this application

ethyl isocyanate. are extraordinarily surprising.

The reaction of component E with the alkoxy 55 Otherwise, it is also possible to use the

methyl isocyanates is carried out according to known, customary coating compositions in that

Process in substance or solution, for example first one of the components, either A

measured the German Auslegeschrift 1 244 410. The reac or B, as usual, and then the monomer

tion with the alkoxymethyl isocyanates can also be done before mixing the other resin B or A in the presence

the mixed polymerization or it can 60 of the initially charged and fully polymerized resin A

the monomers or B containing OH and NH groups polymerized, with the help of the usual

reacted with the isocyanates, with the remaining mono radical formers, such as peroxides, peresters or azo

mers are mixed and then copolymerized. ties. This particular embodiment possesses

Mixing the elasticizing reactive components has the advantage that subsequent mixing of the

Component B with the brittle component A can be superfluous in some components. The compo-

Solution or in substance in a stirred tank, mixed in this way, an even better one

Screw, an internal mixer or in a kneader compatibility, which is achieved by a partial graft poly-

take place at temperatures of about 20 to about 130 ° C. merization may have been caused. After

Reaction with an alkoxymethyl urethane and after The segment-like structure of elastic and brittle segments is retained after the baking process.

The soft, elasticizing acrylic resins B of this application cannot at room temperatures be pulverized. The hard, brittle component A can be pulverized at room temperature.

The special properties of acrylic resins, such as softness, brittleness or elasticity, are made possible by the average molecular weight, which is determined osmometrically, and by the monomer composition certainly. The molecular weight is determined in a manner known per se with the help of regulating additives, such as mercaptans, via the polymerization temperature and via the stationary concentration of the Initiator radicals adjusted to the desired size, d. H. 5000 to 20,000 for the brittle component A. and 1000 to 5000 for the elastic component B. As already described, the components A and B are mixed in substance or in solution by customary methods. Is mixed in solution, the usual paint solvents, such as aliphatic hydrocarbons, aromatic hydrocarbons, Alcohols, esters, ketones, ethers can be used. For example, as solvents or diluents called:

Aromatic hydrocarbons such as toluene, xylene, chlorobenzene; Carboxylic acid esters, such as ethyl acetate, butyl acetate, Glycol monomethyl ether acetate and glycol monoethyl ether acetate; Ketones, such as methyl ethyl ketone, Methyl isobutyl ketone, cyclohexanone; Alcohols such as ethanol, butanol, ethylene glycol, butylene glycol, ethylene glycol monobutyl ether, -monomethyl ether, -monoethyl ether. Mixtures of the aforementioned can also be used Solvents are used.

The solid binders - for example in powder form - can in turn be removed from the solutions by evaporation in a screw and subsequent grinding roughly according to the method of the German Patent application P 20 05 691.1 can be obtained. For the production of powders from the solutions of the binding agents Precipitation processes can also be used. However, the solutions can be used directly as a coating agent can be used.

The coating compositions according to the invention can contain conventional auxiliaries in the solid or dissolved state, how pigments, fillers, soluble organic dyes, catalysts, leveling agents are added, namely soluble organic dyes. Catalysts and leveling agents (such as cellulose acetobutyrate) in Quantities from 1 to 50 percent by weight, based on solid binder.

Pigments and fillers can be used in amounts of 5 to 20 parts by weight, based on 100 parts by weight of solid coating composition.

The following pigments come into question, for example: White and colored pigments, such as titanium dioxide, chromium oxides, Iron oxides, zinc oxides, mixed oxides of cobalt, nickel and manganese; Selenides and Sulphides of Zinc and cadmiums such as zinc sulfide, cadmium sulfide, cadmium sulfide selenides; Chromates such as zinc, lead or strontium chromate, chrome yellow, Prussian blue, Brunswick Green, lithopone, organic pigments such as phthalocyanine pigments or insoluble azo dyes. The following fillers may be mentioned: precipitated or thermally obtained silicas, silicates, talc, mica, Quartz powder, barium sulfate, calcium sulfate, aluminum oxide, glass powder.

The pigments can be mixed with the fillers.

To achieve an anti-corrosive and decorative effect, the paints can contain Contains aluminum bronze and zinc dust. Such “metal effect paints” have an extraordinarily good one Weather resistance. The coating compositions are therefore preferably used for metal effect finishes.

ίο Those produced with the coating compositions according to the invention Coating agents are used in powdered or dissolved form, in the case of Solution the solvents already mentioned are used.

The coating agents can be used in a wide variety of known techniques of spraying, dipping, spraying and painting methods, such as electrostatic ones, can be applied to the object to be coated Spray process, fluidized bed sintering process, flame spray process, etc.

The stoving temperatures can be 120 to 35O ° C, preferably 130 to 300 ° C. The burn-in time depends on the type of composition of the coating compounds and is usually between 30 seconds and 60 minutes.

If the coating compositions according to the invention are mixed with urea or melamine-formaldehyde resins in amounts of 5 to 40 percent by weight and with 0.5 to 6 percent by weight of an acidic catalyst, always based on a 100% solid mixture, no improvement in the technical properties of the paint is achieved after baking However, surprisingly, the baking temperatures to temperatures can be below 90 ⁰ C, preferably 60 to 8O ⁰ C, lower. A prerequisite for this is that component B reacted with alkoxymethyl isocyanate

(1) is a primary hydroxyl group-containing monomer.

The same reduction in the stoving temperature can be achieved if in the inventive Coating compositions the component A a) an N-methylol compound or an N-methylol alkyl ether des (Meth) acrylamide is component B a) from one or more monomers with primary hydroxyl groups and 0.5 to 6 percent by weight of an acidic catalyst, based on solid polymer mixture, can be added.

The coating compositions produced with the coating compositions according to the invention have a wide range of uses. Because of their strength, elasticity with simultaneous high surface hardness and their good quality Chemical and weather resistance, they are suitable as equipment paints, can interior paints, as automotive paints, Wire enamels and as luminous paints. They are preferably used for the production of chemical-resistant products Protective coatings and for metal strip coating and for the heating of metal effect paints the wet-on-wet process. Sheets coated with the coating compositions according to the invention can deformed and folded.

Although objects made of metals, for example steel, cast steel, copper, brass, bronze, gunmetal, aluminum and its alloys are preferably coated or coated, the means can also serve to coat or cover objects made of glass, ceramics, porcelain and plastics.
The parts and products given in the examples

409538/331

percentages relate to weight, unless otherwise stated.

Manufacture of the hard component A.

Binder A 1

In a mixing vessel equipped with helical stirrer, a mixture of 375 g of styrene, 165 g ethylhexyl acrylate, 150 g methacrylic acid, under nitrogen, 2-hydroxypropyl, 165 g acrylamide, 30 g of tert-dodecyl mercaptan, 100 g of xylene, 100 g of methyl glycol acetate and submitted to 130 ⁰ C brought. Within one hour, the mixture is stirred under cooling, 10.5 g of tert-butyl perpivalate than 75 "" solution in white spirit _(Κρ 7β0. To 15O ⁰ C) The internal temperature to rise to 14O ⁰ C Subsequently, in one hour. 7. g di-tert-butyl peroxide was added dropwise. After another hour, the volatile constituents in vacuo be distilled off at 160 ⁰ C and poured the coating melt onto a metal sheet. After cooling, results in a hard, easily pulverizable resin having a molecular weight of 7000. the resin can be in Xylene can be dissolved to 50 " _o.

Binder A 2

In a stirred tank to 1000 g of ethylglycol acetate and presents dropwise thereto at 130 ⁰ C over 5 hours a mixture of 400 g of styrene, 300 g butyl acrylate, 100 g methyl methacrylate and 200 g methacrylic acid-2-hydroxypropyl. 1 g of methacrylic acid and 15 g of tert-butyl peroctoate are added. The mixture is then left for a further 5 hours at 130 ^° C. and the volatile constituents are distilled off at 250 ^° C. and 2 mm Hg on a thin-film evaporator. The hot melt solidifies to form a brittle resin with an average molecular weight of 5900 and an OH number of 76.

Binder A 3

A mixture is prepared from 600 g of butyl glycol, 60 g of acrylamide, 30 g of acrylic acid, 60 g of 1,4-butanediol, 180 g of methyl acrylate and 360 g of ethyl acrylate. 300 ml of the mixture are ^{brought to 100 °} C. in a flask and the polymerization is started under nitrogen with a few drops of tert-butyl peroctoate. The remainder of the mixture is then added over the course of 6 hours, together with 12 g of tert-butyl peroctoate, and the mixture is stirred for a further 5 hours. After evaporation of a sample, a resin which is hard at room temperature and has an average molecular weight of 9000 is obtained. This lacquer is particularly suitable in combination with component B 2 for metal strip lacquering.

Production of the elasticizing component B Binder B 1

In a stirred vessel, 300 g of butane-l, 4-monoacrylate, 700 g of 2-ethylhexyl acrylate and 200 g of tert-dodecyl mercaptan and heated to 150 ⁰ C. Within one hour, the mixture is stirred 7 g tert-butyl perpivalate as 75% solution in butyl phthalate, and can thereby increase the temperature to 170 ⁰ C. 7 g of di-tert-butyl peroxide are then stirred in over the course of a further hour. By applying a vacuum is freed from the volatile constituents at 180 ⁰ C and cooled while stirring with a Wendeirührer to 6O ⁰ C. 120 g of methoxymethyl isocyanate are then stirred in and, after 2 hours, the mixture is cooled to room temperature. The viscous resin is then taken up in xylene or butyl acetate. The osmometrically determined molecular weight is 3300, measured in acetone.
5

Binder B 2

700 g of xylene are placed in a stirred pot under nitrogen and for this purpose within 3 hours

ίο a mixture of 300 g of butanediol monoacrylate, 700 g of ethyl acrylate, 15 g of tert-dodecyl mercaptan and 15 g of tert-butyl peroctoate was added dropwise under reflux. The mixture is then stirred for a further 5 hours, cooled to 45 ° C., 0.5 g of tin dioctoate is added and 175 g of methoxymethyl isocyanate are stirred in. After 12 hours and 45 ^° C., 300 g of n-butanol are added and the mixture is cooled. After careful evaporation, a rubber-elastic film with an average molecular weight of 3600, measured in acetone, remains.

20 binder B 3

Preparation as for B 1, but instead of 1,4-butanediol monoacrylate, 300 g of 2-hydroxyethyl methacrylate are used used. A reactive resin with a molecular weight which is syrupy at room temperature also results 3500.

Preparation of the paint mixture by polymerizing the monomers of the hard component A in the presence the polymerized soft component B

Binder C

1000 g of component B 1 (see above), but not yet reacted with methoxymethyl isocyanate, are dissolved in a mixture of 500 g of styrene, 300 g of butyl acrylate and 200 g of 2-hydroxypropyl methacrylate. The mixture is brought to 130 ^° C. and 7 g of tert-butyl perpivalate as a 75% solution is stirred into white spirit over the course of one hour. The temperature rose to 160 ⁰ C. Subsequently, there was 7 g of di-tert-butyl peroxide and removes the volatile components after a further hour in a vacuum at 170 ⁰ C. The still hot coating melt is in a reaction screw at 120 ° C and 4 Minutes residence time with 6 percent by weight, based on the resin mixture, reacted methoxymethyl isocyanate. The melt modified in this way is allowed to solidify. After dissolving in xylene, the resin can be used for metal effect coatings (molecular weight of the binder C approx. 6600).

55

example 1

To produce a stoving enamel suitable for continuous metal strip painting, mix: 100 parts of the solution of the binder A 3 ii butyl glycol (as described under Binder A 3 with 30 parts of the solution in binder B 2 - as stated under binder B 2 - and pigmented by rubbing with a funnel mill with 100 / j titanium dioxide rutile type (based on the solid: of the mixture). The white lacquer is applied to degreased iron sheets with a hand coater and burned without venting. The properties of the cured paint films are shown in the following table reproduced:

11 90 see 80 60 see Stoving conditions .... 26O ⁰ C HB 300 ° C 20 µ 1 20 µ Layer thickness t Impact deepening to Gard 80 ner (inch / pound) 1 HB Pencil hardness DIN 46 453 .. 9.8 1 Cross-cut DIN 53 151 .. (Sheet metal crack) T-bend test exam after Journal of Paint Techno Well IVa logy, 40 (1968), p. 58 A .. Well 9.5 Erichsen recess DIN 53156 Surface hardness / scratch Well strength Well shine

on the solid). Part of the mixture is then pigmented with a 50% xylene paste commercially available very fine aluminum bronze, adds paint additives (flow control agent, plasticizer), diluted with isopropanol to spray viscosity (DIN-4-Becher-14 see). Then you spray on smooth degreased Iron sheets and airs off briefly.

Then the unpigmented clearcoat, which is also spray viscosity, is applied with a second spray gun is diluted, sprayed on and baked for 30 minutes at 120 ° C. You get a very bright one uniform metallic effect. The sheets are practically unchanged after 1 year of storage in a maritime climate.

Comparative example 1 versus example 2

The paint films have good resistance to toluene and have excellent resistance to weathering in the Florida climate.

Example 2

The one described as binder A1 containing hydroxyl groups Lacquer resin is dissolved in xylene and mixed with the component described as binder B 2 mixed so that the ratio of the two substances is 10: 3 and the resulting solution is 50% is. 1000 parts of this solution are pigmented with 250 parts of titanium dioxide of the rutile type in a funnel mill, diluted with xylene to spray viscosity and sprayed the paint with a compressed air spray gun Body panels that have been treated with a commercially available epoxy primer and burns afterwards briefly ventilate. The properties of the top coat are shown in the following table:

Stoving conditions 30 min., 120 ° C

Layer thickness of the top coat .... 45 μ
Gardner impact deepening

(inch / pound) 20

Pencil hardness DIN 46 453 3 H.

Erichsen recess DIN 53 156 5.9

Mandrel bending test ASTM D-522-41 1.0 cm cracks gloss according to Gardner ASTM

D-523-536 97

Resistance to solvents
5 minutes - xylene lightly labeled at room temperature

then 20 minutes of storage

unchanged in the air

Resistance in the Sun-shine Weatherometer XW after 700 hours, no chalking, good
Gloss retention

Example 3

For producing a metal effect coating, the "in the two-layer system wet to be applied in wet" to use the cited in Example 2 of acrylate mixture, adding to the solution another 15% hexamethoxy methyl amine, and 1% p-toluenesulfonic acid (relative This example demonstrates that films of a copolymer of the overall composition according to Example 2 do not have the same favorable properties in terms of surface hardness, gloss and elasticity as films of the mixture of Example 1.
165 g of acrylic acid amide, 150 g of 2-hydroxypropyl methacrylate, 165 g of ethylhexyl acrylic ester, 375 g of styrene (monomers of component A 1), 77 g of 1,4-butanediol are then placed in a 3-1 glass flask with a helical stirrer and 180 g of ethyl acrylate (monomers of component B 2) and 20 g of tert-dodecyl mercaptan. The mixture is heated the contents under nitrogen to 120 ⁰ C, and polymerized by dropwise addition of 10 g of tert-butyl perpivalate dissolved in dichloroethane 20 g within 3 hours. The temperature rises to 160 ⁰ C.

4 g of di-tert-butyl peroxide are then added dropwise and, after a further hour, the mixture is cooled to 110 ^° C. 46.5 g of methoxymethyl isocyanate are stirred in and, after a further 5 minutes, it is diluted with butyl glycol to a solids content of 50%. The cooled paint is rubbed with 50 parts by weight of titanium dioxide, based on 100 parts by weight of solid product, and sprayed onto body panels as in Example 2. The properties of the top coat are shown in the following table:

Stoving conditions 30 min., 120 ° C

Layer thickness 45 μ

Impact depression inch / pound 6

Erichsen recess DIN 53 156 3.0

Mandrel bending test 2.0 cm cracks

Pencil hardness H

The shine is veiled.

Comparative example 2

In comparison with Example 1, in which two binding medium A 3 and B 2 were combined, you will binder A 3 and B 2 Example 1 getrenni tested in accordance with.

Both binders are, as indicated in Example 1, abraded with 100% rutile titanium dioxide and baked. The properties of the paint films are given in the table below. It can be seen from this that both binders alone do not achieve the valuable properties of their mixture by far.

Binder B 2

Binder A 3

Stoving conditions

Layer thickness

Pencil hardness DIN 46 453

Stroke deepening according to G ard η er
(inch / pound)

T-bend test

Erichsen recess DIN 53 156

Cross-cut DIN 53 15Ί (May 1955)

Scratch-resistant wedge / surface

shine

Resistance of the films to toluene

90 sec, 260 ^° C

20 µ

<6B

60 sec, 300 ⁰ C

20 µ

<6B

because of the stickiness of the surface and the insufficient hardness of the film no measurements are carried out.

good i good

Toluene completely removes the paint film from the metal sheet.

90 sec, 260 ^° C
20 µ
2 B

9.0
1

small amount
Well

60 see, 300 ° C
20 µ
2 B

8.8
1

small amount
Well

Films initially swell in toluene
very strong, stand out and
dissolve themselves.

Example 4

The following Examples 4 to 12 demonstrate that the coating compositions according to the invention, if they are mixed with melamine-formaldehyde resins and an acidic catalyst, can be stoved at temperatures ^{as low as 80 °} C. to form solvent-resistant and scratch-resistant coatings.

A prerequisite, however, is that the copolymer mixture of copolymerized units is primary Contains hydroxyl-containing monomers, the primary hydroxyl groups with a Alkoxymethyl isocyanate have been implemented in whole or in part. In the examples below, such component used an acrylic resin containing methylmethyl urethane groups, which consists of polymerized units of a 1,4-butanediol monoacrylate or a p-hydroxyethyl methacrylic acid ester and subsequent reaction with methoxymethyl isocyanate has been obtained.

17 kg of xylene, 6 kg of butanediol-l ^ monoacrylate, 14 kg of ethyl acrylate and 300 g of acrylic acid are placed in a 40-liter kettle under nitrogen. The mixture is heated to reflux temperature and 300 g of tert-butyl peroctoate are added dropwise over the course of 3 hours. 100 g of di-tert-butyl peroxide are then added and the mixture is refluxed for 8 hours. It is cooled to 50 ⁰ C, add 10 g of tin dioctoate, and stir 95 mole percent, based on butane-l, 4-monoacrylate, one of methoxymethyl isocyanate. After about 30 minutes, 3 kg of methanol are stirred in and the mixture is cooled to room temperature.

The solution, adjusted to 50% solids, is mixed in a weight ratio of 3:10 with a 50% solution of a commercially available, externally crosslinking acrylic resin, consisting of 25 percent by weight styrene, 4-5 percent by weight ethyl acrylate, 10 percent by weight ethylhexyl acrylate, 10 percent by weight methacrylic acid-hydroxypropyl ester, 10 percent by weight Acrylamide is mixed in a xylene-butanol mixture 2: 1 (weight ratio) from £ and mixed with 15%, based on solid acrylic resin, hexamethoxymethylmelamine and 3 percent by weight tartaric acid. Now equal parts, based on the solid content of titanium dioxide, of the rutile type are mixed in on a roller. The paint is diluted to the spray viscosity with xylene (flow time: 45 seconds, DIN 4 cup) and sprayed onto primed body panels (thickness of the primer: 30 μ). The coatings are baked after a short flash-off, namely 30 minutes at 80 ^c C. The films have the following properties:

Baking 30 min., 8O ⁰ C

Layer thickness of the top coat ... 50 μ
Stroke deepening according to G ard η er

(inch / pound) 18

Mandrel bending test according to

ASTM D-522-41 not cracked

Pencil hardness 3H

Cross-cut test DIN 53 151 1
Surface hardness (fingernail test) no

last of the

Paint surface gloss according to G a r d η e r

ASTM D 523-536 97

Erichsen recess DIN 53 156 7 mm

Solvent resistance

6 minutes - xylene lightly labeled at room temperature

then 2 hours of regeneration in the air unchanged.

B e i s ρ i e 1 e 5 to 12

For the production of acrylic resins with methylmethylol urethane groups of primary alcohols (soft component B; Examples 5 to 7), the monomers and solvents are used together with the in the controller indicated below is heated to reflux temperature under nitrogen. Within 3 hours are added dropwise 20 g of tert-butyl peroctoate and stirred until the solids content of 50% is reached. Existing moisture is removed by brief distillation. Then at 60 ° C 95 mol percent, based on methacrylic acid iS-hydroxyethyl ester, stirred in methoxymethyl isocyanate and 0.6 g of tin dioctoate. After 30 minutes it sets 50 g of isopropanol are added to the mixture.

Xylene

Ethyl acrylate

Methyl acrylate

Butyl acrylate

Methacrylic acid

/ J-hydroxyethyl ester
tert-dodecyl mercaptan

Example 5 (g)

1000

420 280

300

Example 6 (g)

1000 700

300 10

Example 7 (g)

1000 350

350

300 10

To produce the externally crosslinking acrylic component (hard component A), the solvents Monomers and regulators of Examples 8 to

Xylene

Styrene

Isopropanol

Acrylamide

Methacrylic acid / 9-hydroxypropyl ester

Ethyl acrylate

Methacrylate

Butyl acrylate

Ethylhexyl acrylate ...

tert-dodecyl mercaptan

1 9 Examples 11 8th 600 10 600 600 400 600 400 400 375 400 375 250 165 375 165 165 150 165 150 150 310 150 145 - 295 200 - 140 - 110 165 - 20th - 20th 20th 20th

12th

600 400 250 165

150

135

200 100

20th

mixed and heated ^{to 80 ° C.} The mixture is filtered while it is still hot. About 200 ml of this mixture are placed in a 3 liter flask under nitrogen.

While refluxing, the remainder of the mixture is pumped in warm (about 40 to 60 ° C.) over the course of 5 hours and at the same time 15 g of tert-butyl peroctoate are added dropwise. Then bringing the internal temperature to 100 ⁰ C, adding 5 g of tert-butyl peroctoate and stirred at 100 ⁰ C for 5 hours. The paint solution is clarified using a pressure filter.

For producing a firable at 80 ⁰ C coating the solutions of Examples 5 to 7

ίο each with solutions from Examples 8 to 12 as above mixed that to 3 parts by weight of solid from Examples 5 to 7 10 parts by weight of solid from the examples 8 to 12 are omitted. Based on the solids of the mixture, 15% each are hexamethoxymethylmelamine and 3% tartaric acid added and, as described in Example 4, pigmented and primed Body panels applied.

The binders of Examples 5 to 7 can be used after mixing with 15 percent by weight hexamethoxymethylmelamine and 3% tartaric acid according to Bake conditions of Example 4 at 80 ° C within 30 minutes to form solvent-resistant coatings, however, the films have insufficient surface hardness (pencil hardness worse than HB).

as the binders of Examples 8 to 12 give, after addition of 15 weight percent and 3 weight percent Hexameihoxymethylmelamin tartaric acid within 30 minutes at 8O ⁰ C films that are not solvent resistant. After 6 minutes of placing a cotton ball soaked in xylene, they become detached from the body panel.

The following table shows the lacquer technical data of films of mixtures according to the invention (Examples 5 to 12) listed after the addition of

Hexamethoxymethylmelamine and tartaric acid were stoved at 80 ^° C. for 30 minutes.

7 and Binder mixture from the examples I 5 and 12 I.

6 and 9

Stoving condition

Layer thickness of the top coat

Impact deepening according to G a r d η e r (inch / pound)

Mandrel bending test according to

ASTM-D-522-41

Pencil hardness

Cross-cut test DIN 53 151 ..

Surface hardness (fingernail test)

Gloss according to G a r d η e r

ASTM D 523-536

Erichsen recess DIN 53 156

Solvent resistance
6 minutes - xylene at room temperature

then 2 hours of regeneration in the air

30 min., 8O ⁰ C for about 50 μ

16

not cracked H

30 min., 80 ^° C
about 50 μ

18th

not torn

30 min., 80 ^° C
about 50 μ

16

not torn
H

no damage to the paint surface

96 93

6.6mm 6.5mm 6.4mm

slightly marked unchanged slightly marked
unchanged

slightly marked
unchanged

Claims (1)

Claim: Firmly adhesive coating compounds for metals based on acrylate, consisting of a mixture of A. 10 to 90 parts by weight of an externally crosslinkable Intermediate molecular weight interpolymer from 5,000 to 20,000 which has been prepared by interpolymerization of a) 10 to 90 percent by weight of at least one ester of acrylic and / or methacrylic acid with 1 to 20 carbon atoms in the alcohol component b) 0 to 50 percent by weight of at least one hydroxyl-containing, olefinically unsaturated, copolymerizable monomers, c) 0 to 40 percent by weight of at least one unsaturated carboxylic acid, d) 0 to 40 percent by weight of acrylic and / or methacrylic acid amide or at least one N-substituted derivative of acrylic and / or methacrylic acid amide, e) 0 to 50 percent by weight of at least one monomer from the group styrene, * -methylstyrene, Acrylonitrile, vinyl acetate, vinyl propionate, vinyl alkyl ethers with 1 to 8 carbon atoms in the alkyl radical, methacrylonitrile, allyl acetate, vinyl chloride or vinylidene chloride, the sum of the percentages being 100 and the sole combination of a) and e) is excluded, and B. 10 to 90 parts by weight of a crosslinking with A and soft to rubbery at room temperature Copolymer based on acrylate with an average molecular weight of 1000 to 5000, which has been made from a) 5 to 80 percent by weight of at least one monomer containing hydroxyl groups, b) 20 to 95 percent by weight of at least one ester of acrylic or methacrylic acid with 1 to 20 carbon atoms in the alcohol component, c) 0 to 5 percent by weight of at least one free α, / 9-unsaturated carboxylic acid with 3 to 5 carbon atoms, d) 0 to 50 percent by weight of at least one non-functional monomer and e) 0 to 15 percent by weight of at least one optionally N-monoalkylated acrylic or Methacrylic acid amide, the sum of the percentages being 100, and the copolymer B with 0.1 to 50 percent by weight, based on the total mass, of an alkoxymethyl isocyanate has been implemented.