DE2403755A1 - RHEOLOGICALLY MODIFIED, COPOLYMER LATEX AND AMINOPLAST CONTAINING, AQUATIC COATING COMPOUND FOR DECORATING METALS - Google Patents

Description

RECHTSANWÄLTE 2 4 O 3 7 O ü

DR. JUR. DIi ¹ L-CHEM-WALTER AT

Alfred HOtP ^ Mr *. Jan 25, 19-4

DR. JUR. DlPL-CiIM. H.-J. WOLFP DR. JUR. HANS ChH. ECiL

FRANKFURTAM MAIN-HIGH?

A0ELONSTRASS £ 58

Our Mr. 19 084 Pr / br

Rohm and Haas Company Philadelphia, Pa., V.St.A.

Rheologically modified, copolymer latex and aminoplast containing, aqueous coating compositions for decorating metals

The invention relates to thermosetting coating compositions for decorating metals from aqueous media on the surfaces to be coated are applied. "Decorating metals" means covering a metal sheet with a suitable coating compound, after which the sheet metal is subjected to various mechanical deformation processes subject. Examples of common objects made of decorated metal are beer cans, beverage cans, Vegetable cans, jars with screw caps and aerosol containers. The covers for such items must endure a variety of fabrication treatments without jumping or peeling off. The fabrication vessels range from very mild treatments

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(e.g. the manufacture of can bodies) to extreme strict (e.g. the manufacture of aerosol caps). The coatings can also be applied to previously molded objects apply, such as thorn-shaped two-part can bodies, Toothpaste tubes, etc.

In a typical process for making a finished decorated metal article, a pigmented one is used white base coating material rolled onto a metallic substrate and the coated substrate is baked, a decorative print is then applied over this white base and while the paint is still wet, a clear topcoat is rolled over the paint to protect it. The coated metal sheet is then fired to develop the final hardness. The finished coated metal sheets can then be stacked and for different lengths of time before further processing into the end product be stored. It is essential that the coatings are good Have hot stack resistance in order to avoid that the metal sheets stick to one another, as this will spoil of the coatings. The coated sheets are finally processed into various forms. The requirements of further processing depend on the End use of the material, e.g. whether it will be made into cans, lids, screw caps, etc. Except that the coatings different manufacturing processes that took place on Metal, many end uses require machining or sterilization operations, which are carried out at high temperatures. In such cases the coating has good overheating properties own.

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In order to achieve maximum hot stack properties for coatings, it is desirable to use a thermosetting coating composition to use, which has a high degree of networking after the maps. However, the hardened ones coatings also have sufficient flexibility to to allow their further processing. When the coated metal is subject to strict manufacturing conditions a soft thermosetting resin should be used. However, should the plated metal be relative are subjected to mild manufacturing conditions, a hard thermosetting resin can be used Xierden.

Up until now, decorating metals included the application of primers, the specific protection against corrosion Pigments in non-aqueous vehicles based on a drying oil such as linseed oil, a quick drying one Paint base with natural resins, a mixture of natural and synthetic resins or one with a urea, melamine or phenol-formaldehyde resin modified alkyd resin contained. Such coatings were usually supplied in high boiling solvents to ensure good flow and "Ensure the films run. The solvents are often flammable and of such a nature that during harmful vapors are generated during the coating process. To counter fire and health hazards, For example, protective measures are usually applied by providing recovery systems for the solvent. It is also the focus of recent interest in air pollution control aimed at reducing or eliminating the release of organic solvents into the atmosphere.

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There has long been a need for thermosetting coatings, which can be applied from aqueous media to air pollution, fire hazards and others Problems associated with the use of coating compounds based on organic solvents, to avoid. However, known aqueous systems such as those disclosed in US Pat. Nos. 2,760,886, 2,918,391 and 3,033,811 have been found are described for the coating of metals in the manner according to the invention, i.e. by direct rolling, not as completely satisfactory as they tend to dry out on the roller and cause difficulties cause or blister when the wet products are placed directly in the oven, or because of brittleness subsequently cannot be subjected to severe deformation conditions, or difficult to achieve because of their softness are handled. The main difficulty with systems based on water is rheological To achieve properties that are suitable for rolling these systems directly. Therefore a mass is required which has such flow and leveling properties, that, when applied directly by a roller coater, it is uniform and smooth Forms surface that does not contain streaking. The inadequacy of aqueous emulsions from the standpoint flow is well known in the metal coating industry, see Paint and Varnish Production, February 1964, pp. 28-33- The flow and course of pigmented basecoats is most critical because the pigmentation makes the flow noticeable in aqueous systems reduced.

In the patent application P 22 11 I69.9 are thermosetting Coating compositions are described that apply directly to metals

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can be rolled on and give films a good appearance, which can then be deformed and which after firing give clear or pigmented coatings that have excellent resistance to water and solvents, adhere excellently to a variety of substrates and have a high gloss. The coating compositions described in this patent application are advantageously used / alsenauftragr.aschinen in conjunction with direct-V, wherein V / alzen a low major .inetsrhärte comprise, for example, ο tv / a However, because v verifiable 2 rubber rollers do not possess good Abnutsungoeigenschaften 12 / , it is desirable to provide a thermosetting resin coating composition which can be applied by a direct roller application machine, wherein the rollers have a high Dururnecerhurt, 2. E. about 20 to 50, without impairing the flow and leveling properties,

With the aid of the invention, such a coating mass is obtained made available.

The coating compositions according to the invention are alkaline An aqueous mixture with a binder, which essentially consists of:

A. a latex of a water-soluble addition copolymer made from (1) 28 to 70% of an aromatic monovinyl monomer, (2) 18 to 63 % of at least one ester of acrylic or methacrylic acid, (3) at least one olefinically unsaturated monomer with at least 1 amide or 1 Hydroxyl group and (4) one olefinic

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unsaturated monomer having a carboxyl group, wherein "the amount of (3) is from 1.5 to 3-0 % when the monomer contains an aromatic group, and from 1.5 to 15% when the honor contains a hydroxyl group, and" the amount of (4) is from 0.5 to 5 % based on the total weight of the monomer, the Tg of the polymer is below 45 ° and

B. a water-soluble condensation product of urea oaer triasin with formaldehyde or its water-soluble Methanol or ethanol ether,

wherein the weight ratio of A is to B based on solids, of 35:65 to 65 · "35 _3, the minimum filrahildungstemperatur not higher than about 25 ° C, the mass is a solid content of the composition between 40 and 80 wt -.%; and with the mass of 1 to 5 percent by weight, based on the weight of A and B, of a soluble rheological modifier with an average molecular weight (number average) of about 400 to about 100,000, which is a polyethylene glycol or a polyethylene oxide.

Preferably, B is the reaction product of a urea-formaldehyde adduct with methanol, wherein the molar ratio of urea to formaldehyde to methanol between 1 / 1.75 to 3 / 2-3, 5 is located, or a melamine-formaldehyde adduct with methanol to give the molar ratio of melamine to formaldehyde to methanol is between 1 / 7-10 / 12-17, or mixtures thereof.

In the copolymer A, (1) is preferably styrene or vinyl toluene, (2) at least one ester of acrylic acid and an alkanol with about 2 to 12 carbon atoms or an ester of

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Methacrylic acid and an alkanol with about 6 to about 14 carbon atoms, (3) at least one methacrylamide, acrylamide, Hydroxyethyl acrylate or methacrylate or hydroxypropyl acrylate or methacrylate and (4) acrylic acid, methacrylic acid or itaconic acid.

If the coated metal is to be subjected to severe fabrication treatments, such as the manufacture of aerosol caps or bottle caps, then the copolymer should be a soft copolymer. In this case the weight ratio of aromatic monovinyl / acrylic acid ester / amine-containing or hydroxyl-containing monomer or both / unsaturated acid is in the range from 28-52 / 40-68 / 1.5-5 / 0.5-2, preferably 35-50 / 45-60 / 1.5-3 / 0.5-2, the total amount being 100. The Tg of the soft copolymer should be below 0 ⁰ C, and preferably below -15 ° C. The urea-formaldehyde adduct is usually used for severe post-coating manufacturing conditions, while the melamine-formaldehyde adducts can be used for less severe applications or in cases where there is no deformation or mild deformation of the coated products.

For best results, the coating should contain a volatile base, a tertiary amine being preferred, and should have a minimum film-forming temperature not higher than about 15 ° C.

When the coated sheet metal is to be subjected to mild fabrication treatments, such as deformation to can bodies, or if it oozed after manufacture can be either a soft or a hard one

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Copolymer can be used. Any of the aminoplasts, or a combination thereof, can be used for the less severe Manufacturing operations or for prefabricated items.

The most preferred copolymer is a copolymer of Styrene, butyl acrylate, at least one of the two, namely Hydroxyätliylmethaerylat or methacrylamide, and methacrylic acid.

One of the monomers used to make the addition copolymer used in substantial amount is an emollient or softening monomer that by the following formula can be represented:

R 0

I W
H ₂ C = CC-OR-

wherein R is hydrogen or an alkyl radical having 1 to k carbon atoms and R is the straight-chain or branched radical of a primary or secondary alkanol, alkoxyalkanol or alkylthioalkanol, the alkanol containing 2 to about 14 carbon atoms and its chain length depending on R; Examples are ethyl, methylpropyl, η-butyl, 2-ethylhexyl, heptyl, hexyl, oetyl, propyl, 2-methylbutyl, 1-methylbutyl, butoxybutyl, 2-methylpentyl, methoxymethyl -, sthoxyethyl, cyclohexyl, n-hexyl, isobutyl, ethylthioethyl, methylthioethyl, ethylthiopropyl, n-octyl, 6-methylnonyl, decyl, dodeeyl and the like. When R is an alkyl radical and R.

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also represents an alkyl radical, R should be about contain up to about 14 carbon atoms and if R is V / hydrogen 1

and R is an alkyl radical, R 2 should be to Contains about 12 carbon atoms, making it a soft monomer is present.

Important properties of the copolymer are its toughness and suppleness as well as its influence on the minimum film formation temperature (MPT) of the coating composition. The glass transition temperature (Tg) of the copolymer depends on the choice of monomers and their proportions and their influence on the glass transition temperature. The glass transition temperature is a common criterion for polymer hardness and is described by Flory in Principles of Polymer Chemistry, pp. 56 and 57 (1953), Cornell University Press. Although it is preferred to actually measure the glass transition temperature, it can also be calculated as described by Pox in Bull. Am. Physics Soc. I ₉ 3, p. 123 (1956) is described. Examples of the glass transition temperature of homopolymers that enable such calculations are summarized below:

Homopolymer of Tg

n-octyl acrylate -80 ° C

n-decyl methacrylate -60 C

2-ethylhexyl acrylate -7O ⁰ C

Octyl methacrylate -20 ⁰ C

n-tetradecyl methacrylate - 9 C

Methyl acrylate 9 ° C

n-tetradecyl acrylate 20 ° C

Methyl methacrylate 105 ° Q

Acrylic acid 106 ° C

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These or other monomers are mixed to give the desired glass transition temperature of the copolymer. It is well known that for a given number of carbon atoms in the alcohol content, the degree and type of Branching significantly increases the glass transition temperature. The straight-chain products give the lower glass transition temperature,

The coating compositions of the invention also have a critical maximum film formation temperature. The film formation temperature is determined according to the method described in Resin Review, Vol. 16, No. 2 (1966). This will influenced not only by the glass transition temperature of the addition copolymer, but also by the one used Plasticizers or confluent agents and their amounts. In the case of MFT values that are noticeably above this maximum, difficulties arise in achieving a uniform The coating on and during and after the deformation of the metal is no longer coherent.

The other essential monomers besides the pliability-imparting monomer are the toughening or toughening monomers hard monomers including the aromatic monovinyl monomers, the unsaturated acid monomers and the monomers with functional hydroxyl and / or amide groups. The hardness or softness of the acid monomers and of the other functional monomers is not critical because of the small amounts used. Styrene and vinyl toluene are examples of the monovinyl aromatic monomers.

The unsaturated carboxylic acid can be a simple monocarboxylic acid or a half-ester or a half-amide a ct, ß-unsaturated dicarboxylic acid and dersn

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Salts with a volatile base, such as ammonia; or with a volatile water-soluble amine, such as dimethylamine, dimethylethanolamine, triethylamine, triethanolamine, morpholine, N-methylmorpholine, picoline and the like. Examples of copolymerizable ethylenically unsaturated monocarboxylic or polycarboxylic acids are sorbic acid, Vinylfurancarboxylic acid, α-chlorosorbic acid, p-vinylbenzoic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, aconitic acid, atropic acid, crotonic acid and itaconic acid and mixtures thereof, with itaconic acid and the α, ß-unsaturated monocarboxylic acids, in particular methacrylic acid and acrylic acid, being preferred . Other copolymerizable acid monomers are the alkyl half esters or partial esters of unsaturated polycarboxylic acids, such as itaconic acid, maleic acid and fumaric acid, and the partial amides of these acids. Preferred are the lower alkyl esters Halbester (C. to Cg), such as acid methyl itaconate, butyl itaconate acid, acid methyl fumarate, acid fumarate, methyl maleate and acid butyl maleate _sa ures. According to the invention, these partial esters and partial amides belong to the α, ß-unsaturated monocarboxylic acids.

In addition to the acids, there is also a monomer with an amide group, such as acrylamide, methacrylamide or their methylol or methoxymefchylene derivatives or a honey with a Hydroxyl group, such as hydroxyethyl or hydroxypropyl acrylate or methacrylate, are present. The hydroxyl groups and monomers containing the amide groups can be used individually or together.

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Other ethylenically unsaturated copolymerizable monomers can optionally be used together with the above emollient monomers and toughening monomers Monomers can be used provided that they do not detract from the desired properties of the copolymer (e.g. increase the total glass transition temperature in an impermissible manner). This can be done through the general formula are shown:

RO
H ₂ C = CC-OR ²

where R has the preceding meaning. R is preferably

is
an alkyl radical andA the methyl radical or an alkyl radical with about 3 to about 20 carbon atoms when R is hydrogen, and an alkyl radical with 1 to about 5 carbon atoms or an alkyl radical with about 15 to about 20 carbon atoms when R is the methyl radical. From the above it can be seen that in the case of alkyl acrylates and alkyl methacrylates, the glass transition temperature first falls with increasing chain lengths of the alkyl group and then increases again; that is, it is known that both hard and soft monomers occur in each group of monomers. Examples of these hard monomers and other hard monomers are: methyl acrylate, vinyl acetate, tetradecyl acrylate, pentadecyl acrylate, methyl methacrylate, ethyl methacrylate, t-butyl acrylate, butyl methacrylate and pentadecyl methacrylate.

The coating compositions described here can be used as clear coatings or, as explained below, pigmented with a large number of pigments .

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The preferred emulsion copolymer having a molecular weight of about 70,000 to 2,000,000, and preferably about 250,000 to 1,000,000, is made by emulsion copolymerizing the various monomers in the appropriate proportions. Methods of conventional emulsion polymerization are described in US-PSS 2 75 ¹ * 280, and 2,795,564. Thus, the monomers can be emulsified with an anionic, a cationic or a nonionic dispersant, which is usually used in an amount of about 0.05 to 10 %, based on the weight of the total monomers. The acidic monomer and many of the other functional or polar monomers can be soluble in water so that the dispersant serves to emulsify the other monomer (s). A free radical initiator for the polymerization such as ammonium or potassium persulfate can be used alone or together with an accelerator such as potassium metabisulfite or sodium thiosulfate. Organic peroxides such as benzoyl peroxide and t-butyl hydroperoxide are also useful as initiators. The initiator and accelerator, usually referred to as a catalyst, can be used in amounts of 0.1 to 10 %, each based on the weight of the monomers to be copolymerized. The amount can be adjusted as indicated above to control the intrinsic viscosity of the polymer. Conventionally, the temperature can be from room temperature to 60 G or more.

Dispersants suitable for emulsion polymerization are anionic dispersants, such as the sodium salts of higher fatty alcohol sulfates, for example lauryl alcohol, and higher fatty acid salts, such as oleates or stearates

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of morpholine, 2-pyrrolidone, triethanolamine or mixed ethanolamines, also nonionic dispersants, such as "alkylphenols modified with ethylene oxide, of which the t-octylphenol modified with 20 to 40 ethylene oxide units is a representative example, higher fatty alcohols modified with ethylene oxide, such as with 20 to 50 ethylene oxide units of modified lauryl alcohol, similarly modified long chain mercaptans, fatty acids, amines and the like. Mixtures of nonionic and anionic dispersants are also useful. The preferred composition is made with a nonionic emulsifier, or such an emulsifier is added after the polymerization.

The amount of emulsifier (s) required will vary primarily with the concentration of monomers to be handled and to a lesser extent depends on the emulsifier, monomers and proportions of monomers selected. In general, the amount of emulsifying agent is between 2 and 12 wt. of the monomer mixture, preferably 4 b _ ^. s 7 wt. If the dispersion is to contain a relatively low concentration of interpolymer, a little more than the minimum amount of emulsifier given by the above rule may prove to be desirable. In such a case, the concentration of emulsifier in the aqueous solution can advantageously be at least 1 % of this solution and up to about 7% by weight of the aqueous solution.

As an addition polymerization catalyst, 1 or several peroxides can be used, which act as radical-forming catalysts and in aqueous solutions of the emulsifier are soluble. Are very zv / eckraäig the persulfates, including the arrinoniuni-, ilatriun-

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and Kaliuirjpersulfate or hydrogen peroxide or the Perborates or percarbonates. Organic peroxides can also be used, either alone or together with inorganic peroxides. Typical organic peroxides are benzoyl peroxide, tertiary butyl hydroperoxide, cumene · ^ peroxide, tetralin peroxide, acetyl peroxide, caproyl peroxide, tert-butyl perbenzoate, tert-butyl diperphthalate, methyl ethyl ketone peroxide etc. The preferred organic peroxides are, at least in part, in that of the emulsifying agent containing aqueous medium soluble. The choice of inorganic or organic peroxides depends in part on the particular combination of the monomers to be interpolymerized / some of which are better in one type react than to another.

The amount of peroxide catalyst required is roughly proportional to the concentration of the monomer mixture. Usually it is 0.01 to 3 percent based on the weight of the monomer mixture. The preferred range is from 0.05 to 0.5 % ₃ with the range from 0.1 to 0.25 % usually being best. The optimal amount of catalyst will be determined in part by the nature of the particular monomers selected, including their impurities which accompany particular monomers.

Another suitable class of free radical forming compounds are the azo catalysts. E.g. can be used Azodixsobutyronitril, Azodiisobutyramid, Azobis- (a, ötdimethylvaleronitril), Azobis- (a-methylbutyronitrile), dimethyl-, diethyl- or dibutylazobis- (methylvaleriate). These and other similar azo compounds serve as initiators which generate free radicals. They contain a

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-N = N- group linked to aliphatic carbon atoms, at least one of which is a tertiary carbon atom. Usually O ₅ Ol to 2 % _} based on the weight of the monomer (s) are sufficient-

To effect interpolymerization at a temperature among those at which coagulation might occur it may be desirable to add the catalyst activate. This can best be achieved by using what is known as a redox system, by alongside a reducing agent is present in the peroxide catalyst. Many examples of such systems are known. Reducing agents, such as soluble sulfites, including hydrosulfite, sulfoxalate, thiosulfate, sulfite and Bisulfites can be used. Examples are sodium hydrosulfite, sodium metabi, .sulf it, potassium sulfite, Zinc formaldehyde sulfoxalate and calcium bisulfite. Tertiary amines can also be used. the Redox systems can be activated by the presence of a small amount of a polyvalent metal ion. For this purpose, ferrous ions are usually and effectively used, of which a few ppm are sufficient are.

The amount of reducing agent required will vary somewhat with the peroxide initiator selected, the reduction activating agent (s) and, if used, the metal promoter, also with the emulsifier selected and the particular monomer used. The required amount of reducing agent for practically all systems is within the limits of 0.5 to 6 % ₃ based on the weight of the honey mixture. The preferred amount of sulfite or equivalent is in the range of 0.2 to 1 %.

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The copolymerization is best carried out below about 80 ° C. A preferred range is 15 to 70 ° C, although slightly lower and slightly higher temperatures are also permissible. When most of the monomers have been converted into the interpolymers, also temperatures above 8O ⁰ C can be used. Indeed, after most of the monomers are interpolymerized, the resulting dispersion can be heated to boiling without breaking the dispersion. During interpolymerization, the temperature can be controlled in part by the rate at which the monomers are added and interpolymerized and / or by cooling.

The polymerization can be carried out batchwise by emulsifying all of the monomer feed and polymerized. However, it is usually advantageous to start the polymerization with some of the monomers and add further monomer or further monomers as the polymerization progresses. An advantage the gradual addition of the monomers is optimal in achieving a high content of pesticides Control and maximum uniformity of the product. Another catalyst or other components of the redox system can also be added as the polymerization proceeds.

The water-soluble, heat-convertible condensation products of urea or triazine (e.g. melamine) with formaldehyde and / or their derivatives, which by reaction Achieved with ethanol or methanol can be made by one of the schemes below:

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(1) Control of the reaction conditions so that the degree of polymerization is kept very low, even in the monomeric Condition, and

(2) Introduction of hydrophilic groups into the molecules of the polymeric condensate. They can thus be prepared by careful control of the reaction conditions, as described in Schildknecht "Polymer Processes", Vol. X, pp. 295 ff (Interscience Press, 1956). The preparation of another class of compounds useful in the present invention, such as N, N ¹ -bis (methoxymethyl) urea, is described in Bull. Chem. Soc. Japan, Vol. 11, No. 3 (1936). In a preferred embodiment of the invention, a mixture of a urea-formaldehyde adduct with methanol and a melamine-formaldehyde adduct with methanol is used for the coating compositions.

The coating compositions according to the invention preferably contain a substance which is referred to as a "confluent" or "cosolvent". These substances promote the fusing of the film during air drying prior to firing and promote the flow of the coating during the firing cycle. However, because they are volatile, they do not form part of the final coating. They are characterized by having low water solubility, being good solvents for the uncured polymer mixture, being less volatile than water so that they remain in the film after the water has evaporated, are sufficiently volatile to be removed from the film will not be sensitive to hydrolysis in alkaline media before the end of the firing cycle, neither at ambient nor at elevated temperatures. They also serve to reduce the surface tension of the aqueous system, thereby wetting the

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Meta11substrats is facilitated. Typical examples are isophorone {3 _a 5 _a 5 "-trimethylcyclohexen-2-one-1), 2-ethylhexanol, diaeetone alcohol, dimethylformamide, alkyl ethers of ethylene glycol and propylene glycol, propanol, butanol and tributyl phosphate. The confluent is preferably in the coating compositions The water-soluble condensation product of urea or triazine with formaldehyde is usually given as a solution with 80 % solids in isopropanol or an equal volume, together with isopropanol and butanol, which are cosolvents Thus, the coating composition will normally contain a confluent even without the addition of additional cosolvent Any confluent having the properties noted above as being useful in latex paints is useful in the present invention.

The heology modifiers which can be used according to the invention are substances that are known in the art. Polyethylene & oils are sold commercially under the name Carbowax. Their manufacture is carried out by Fordyce in J.Am. Chem. Soc, Vol. 61, pp. 1905, 1910 (1939). Preferably a polyethylene glycol having a molecular weight of about 400 to 20,000 is used. Polyethylene oxide is a polyether obtained by polymerizing ethylene oxide. Such substances are under under the commercial name Polyox. For example, you can follow procedures like them U.S. Patents 3,365,404, 3,167,519, 3,251,784, and 3 444 102 are described. The polyethylene oxides have an average molecular weight that does not exceed about 100,000. It may be necessary

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to use conventional methods to depolymerize products obtained under these patents in order to to obtain this molecular weight or lower. Such depolymerized products are commercially available available. The rheology modifier can be added to the coating system at any stage of manufacture, that is, it can be added to the thermosetting resin emulsion during or after its preparation, but it can also the mass at the time of mixing with the condensation product of urea or triazine with formaldehyde can be added.

Both the Polyox and the Carbowax products are essential polyoxyethylene polymers with linear chains and hydroxyl end groups. There can be different end groups present, including ester groups, ether groups, epoxy groups or other groups and whenever im Polyethylene glycols in question are the functionally equivalent linear polyethers with End groups other than hydroxyl groups included. Such end groups that do not have hydroxyl groups should not have more than about 2 carbon atoms. For products that have the molecular weights according to the invention the nature of the end groups in the linear chain has essentially no effect on the rheology imparting properties of the polymer. Under Carbowax type of polyethylene glycols one understands the one who is prepared by starting with water or ethylene glycol and ethylene oxide and in the presence of one polymerized alkaline catalyst. Among polyox polyethylene glycols one understands those which are produced by polymerizing polyethylene oxide under Use of different catalysts in the absence of water or a starter such as a glycol. the the latter can have a molecular weight of several million.

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have and have a relatively broad molecular weight distribution compared to the low molecular weight polyethylene glycols, that were made with a starter. The water-soluble polyethylene oxide materials that suitable for the invention can be made by depolymerization of the products j which have a molecular weight of several Have millions are produced. As stated above, the polyethylene glycols with a "starter, generally very narrow molecular weight distributions. These facts show that the molecular weight distribution of the polyether is not particularly critical and when a molecular weight is given is, it means the average molecular weight (number average).

The exact mechanism by which the polyethylene glycols and polyethylene oxides act as modifiers of the theological The properties of the coating compositions are not known. Work in the quantities in which they are used sideicht as a thickener for the masses, but rather actually reduce the viscosity of the masses. It is believed that these compounds with the urea or Triasin-formaldehyde condensation product form a complex, which causes the normal rapid increase in viscosity, that with a relatively small increase in solids in the coating compositions in the absence of the rheology modifier takes place, is reduced. While the coating composition without the rheology modifier. very fast can solidify, causing streaking in the final coating, the coating compositions flow, which the Contain rheology modifiers before solidifying to form a smooth coating. According to the invention

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a synergistic effect between the urea or ■ Triazine-formaldehyde condensation product and the rheology " modifier obtained while achieving improved flow properties. That means the improvement of the flow properties is much greater than the additive effect of the condensation product and the rheology modifier each can be attributed to itself.

Since it is desirable for the mixture of the acrylic dispersion and the aminoplast to become stable during prolonged storage and since aminoplasts are reactive under acidic conditions, the mixture must be made alkaline will. A volatile base, such as ammonia, or a tertiary amine, as it is associated with the salts the acidic monomers discussed is used to make the system alkaline as tertiary amines are not react with the formaldehyde of the aminoplast. The tertiary amines also act as corrosion inhibitors, though the coating compositions according to the invention are used for coating metals. The tertiary amine must be sufficient volatile in that it is driven out of the coating during curing. However, it must not be so be volatile that it suddenly evaporates from the coating j when the coating composition is applied by spraying. Particularly preferred because of its balanced properties, accessibility and economy becomes triethylamine. The pH of the mixture should be kept in the range of 9 to 11 to be good Ensure storage stability. It is clear, however, that the initial pH control alone is not enough a corresponding stability and retention

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to ensure the properties, as with ammonia on Samples neutralized to the desired pH range are not sufficiently stable after prolonged storage, although Satisfactory coatings are obtained if the masses neutralized with ammonia shortly after Manufacture to be used. However, if the tertiary amine is the predominant nitrogen base, small Amounts of ammonia can be used with no adverse effects. The amounts of amine vary depending on the one used special composition, but are in the range of 1 to 5 parts by weight per 100 parts by weight of the coating composition (Solid basis). A preferred embodiment used 2 parts by weight per 100 parts by weight of the coating composition (solids basis). "-

When using pigments, the addition of a dispersant is advisable essential. Although a variety of dispersants pigments work satisfactorily dispersing, the effect of the dispersing agent on the properties of the finished coating must be considered will. Many dispersants are present in the finished coating in unchanged form and have an adverse effect thus the resistance of the transfer to water in a serious way. Other dispersants affect the stability of the system into which they are incorporated.

According to a preferred embodiment, v / earths are used as dispersants the ammonium and lower amine salts of polymeric carboxylic acids are used. So are the ammonium and lower ones Amine salts of polyacrylic and polymethacrylic acids and similar salts obtained by copolymerization of methyl vinyl ether polymeric acid obtained with maleic anhydride suitable,

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- 2k -

A particularly preferred embodiment uses the ammonium salt of hemiamide or the diammonium salt of a diisobutylene maleic anhydride copolymer having a number average molecular weight of about 2,000 to about 4,000. The amount of dispersant used varies depending on the amount and nature of the pigments used and the The amount and nature of the mass used as a binding agent. In general, however, from about 0.3 to about 3.5 parts by weight (pesticide basis) per 100 parts by weight of pigment is found to be effective in dispersing the pigment.

It appears that the dispersants of the type described above work well with those used for the firing cycle Temperatures decompose and ammonia or lower amines become free, which then evaporate. It is also believed that the carboxylic acid esters either with the amide group of the copolymer or react with the aminoplast or both and become insoluble. Independent of . occurring reaction mechanism is evidenced by the fact that this particular class of dispersants, if it is applied in the manner described, the excellent resistance to water and the other extremely desirable properties of the coatings are not adversely affected by such catalysis entry. It has been shown that even clear coatings containing a small amount of these dispersants have a better resistance to water and solvents than the same masses without a dispersant, with both samples cured under exactly the same conditions. The amount of dispersant used in clear coatings will vary depending on the application Amount of aminoplast used. About 0.1 to about 1.0 part by weight of dispersant per 100 parts by weight (solid

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basis) of the coating compound cause the desired catalysis.

The coating compositions according to the invention can be used as clear coatings are used, i.e. as non-pigmented clear top coatings or as pigmented coatings. If pigments are used, the ratio of pigments to the solids of the coating can be wide The range will vary, depending on the pigment used and the specific application. So the ratio can Pigment, to fast substances of the coating from 1:20 to 20: 1 be. The clear coats are especially valuable as top coats that are used to seal underlying to protect decorative coatings without impairing the decorative effect. Da.die transparent coatings according to the invention good clarity, high gloss, excellent resistance to solvents and water and have high adhesion to a variety of surfaces, they are ideally suited as top coats.

Although the coating compositions according to the invention are particularly suitable for decorating metal, they can on A large number of substrates can be applied, the only restriction being that the substrate complies with the firing cycle able to withstand, which is essential for the manufacture of the coatings. Metals are special suitable regardless of whether they have a primer coat or not. So are iron, steel, chrome-plated Steel, tin-plated steel, aluminum, copper, bronze or brass in sheet metal or rolled up with a Thickness of 1.27 to 5.08 mm excellent substrates for the coating compositions according to the invention. Ceramic surfaces and in some cases "wood surfaces" are also suitable as substrates

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Reverse roll coating is the thickness from 0.00127 to 0.127 mn, preferably from 0.0051 to 0.038 mm without curing.

A large number can be used for the coating compositions according to the invention used by pigments. However, these pigments must be stable and may be used under alkaline conditions, i.e., pH from about 9 to about 11, do not react. Typical suitable pigments are titanium dioxide, Iron oxide, calcium carbonate, barytes, and numerous types of clays.

The coating compositions according to the invention are particularly suitable for application using a direct roller applicator, but can also be applied using other means, such as a reverse roller applicator or a spray gun. A single roller applicator normally applies the coating to the substrate while the applicator roller rotates in a basin with the coating mass. The coatings are then baked about 1/2 to 10 minutes at a temperature of about 121-177 ⁰ C. Firing or curing will volatilize all of the volatiles in the coating including residual water, traces of monomers, co-solvents and the tertiary amine. It is particularly important that the tertiary amine is volatilized because it inhibits the hardening of the aminoplast. The firing process causes the ammonium or amine salts of the polymeric carboxylic acids to decompose, apparently leaving behind the acidic form of the copolymer, which can then react with the other components and become insoluble.

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The aminoplast is crosslinked during the firing process and makes the whole coating insoluble.

Applied to alodine aluminum (Q Panel 612, MIL-C-5441, 0.63 Hun thick), dried, with a dry coating thickness of 0.025 ¹ J mm and after a 60 second firing time at 260 ° C., a soft resin coating according to the invention holds the following conventional ones Test conditions from: 1-T bending test, 2-T bending test, 9.3 cm ν kg direct _{impact impact test and 25 3} 5 cm.kg reverse impact strength test.

The following examples serve to further illustrate the invention.

example 1

An emulsion copolymer latex made of styrene / isobutyl acrylate / hydroxyethyl methacrylate / methacrylic acid in the weight ratios of 38.5 / 50/10 / 1.5 (50% by weight total solids in water) was with a water-soluble melamine-formaldehyde adduct, which by reaction with methanol had been modified in a molar ratio of melamine / formaldehyde / methan-ol of 1 * 7: 12 (80% total solids in a volume mixture of equal amounts of isopropanol and butanol) and 1.3 %, based on the weight of the total solids, of a polyethylene glycol having a molecular weight of about 20,000 (Carbowax 20M) blended. The weight ratio of copolymer to adduct in the blend was 60: 4. The pH of the mass was adjusted to 9.5 by adding triethylarain. The resulting mass had a viscosity of 150 to 300 cP, a total solids content of 55 wt .- * and a density of 1.06 g / cm. The weight ratio

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from water to alcohol in the system was 88: '12. the Mass was applied to 40.8 kg of tin-plated steel as a clear topcoat for can bodies at one speed of 46 m / min, with a urethane roller with a durometer hardness of 20 rolled on directly. The flowing and dissolving the crowd was very good. The coated panels were baked at 163 ° C for 10 minutes, one evenly smooth, hard coating with good scratch resistance received.

Example 2

A Emulsionscopolymerlatex of styrene / butyl acrylate / methacrylamide / methacrylic acid in a weight ratio of 42/54 / 2.5 / 1.5 (50 wt -.% Of the total solids in water) was mixed with a water-soluble urea-formaldehyde adduct by reaction with methanol had been modified and its molar ratio urea / formaldehyde / methanol 1: 2.5: 3 (80 wt .-% solids mixed in isopropanoDb-ef ^ j. The weight ratio of copolymer to aduct was 60: 4. 80 parts by weight of this mass were mixed with 20 parts by weight of a melamine-formaldehyde adduct, which had been modified by reaction with methanol and the molar ratio of melamine / formaldehyde / methanol 1: 7. was 12, and 1.3 wt -% of a polyethylene glycol with a Molecular weight of about 20,000 (Carbowax 20M) was added. The pH of the mass was adjusted to 9.7 by adding triethylamine. The mass had a total solids content of 60% by weight and a viscosity of 50 cP. It was a ball mill grist made in 225 parts by weight of this mass, 225 parts by weight of a DuPont Rutile R-96O pigment, 10 parts by weight of solvent

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Water / butyl cellosolve in a ratio of 1: 1) and ball milled small amounts of a pigment dispersant, wetting agent and antifoam agent. The mixture was ball milled for 16 hours and the pigmented coating was removed using a '' Direct roller application machine with urethane rollers of a high durometer hardness (20 durometers) on 40.8 g tin-plated Steel as a white base for can bodies is applied at a speed of 46 m / min. the The flow and leveling properties of the coating composition were very good. The coated panels were baked at 163 ° G for 10 minutes. It became evenly white, smooth coatings received.

Examples 3 and 4

The procedure was as in Example 2, but replaced Carbowax 20 M with an equivalent amount of Carbowax 400 (Example 3) and Carbowax 600 (Example 4). The masses showed good flow and leveling properties when applied directly a metal substrate were rolled on.

When each of Examples 1 to 4 above was repeated, but omitting the Carbowax, the Compounds do not have acceptable flow and leveling properties.

example 5

Repeating the procedure of Example 2, but replacing the PoIyäthylenglykol this example by a polyethylene oxide (3 wt -.% Y based on the solids) with an average srnolekulargewicht of around 100 000 (polyoxy ViSRM-IO) The mass had improved flow and leveling compared to that obtained when the polyethylene oxide was omitted.

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Example 6

A mixture of an emulsion copolymer latex and a urea-formaldehyde adduct was prepared as described in Example 2 and mixed with 2 wt. a liquid mixture of triethylamine and 2.5 wt. Carbowax 20 sts staggered. The mass had a total solids content of 60 % and a pH of 9.0.

The following components, given in parts by weight, were grind in a ball mill:

45 parts of DuPont Rutile R-960 pigment, 45 parts of the mixture described above, 10 parts of solvent (water / butyl cellosolve in a ratio of 1: 1), 0.75 % pigment dispersant, 0.5 % wetting agent, 0.5 % antifoam. The mixture was ball milled for 48 hours. This resulted in a solids content of about 54 %.

To produce a clear coat, the mixture of urea-formaldehyde adduct and latex was simply diluted to 45% total solids with the same solvent _; and 1 wt. a wetting agent was incorporated into the mass. In this and the following examples, the masses were directly rolled on (Union Tool No. 5) at a speed of 46 m / min, with hard rollers made of neoprene rubber or polyurethane, with a dry film thickness of 0.0051 to 0.0102 mm in both cases that formed dry coatings.

The pigmented coating was applied to 40.8 kg zinnplatierten steel and to 0.62 mm thick anodized aluminum panel, the panels were baked at 163 ⁰ C for 10 minutes, a Naßdruckfarbe was applied

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and the clear topcoat applied immediately over the wet ink and baked at 163 ° C for 10 minutes. The flow and leveling properties of both the clear and pigmented coatings were acceptable.

Example 7

Example 6 was repeated, but using a latex which had been prepared by emulsion polymerization of styrene / butyl acrylate / hydroxyethyl methacrylate / methacrylic acid in a ratio of 43/54 / 1.5 / I ₃₅ . The flow and leveling properties were good.

Example 8

The procedure of Example 6 was followed, but a latex polymer was used that by emulsion polymerization of styrene / butyl acrylate / methacrylic acid in a ratio of 44.5 / 54 / 1.5 had been made. This is what it is is a polymer not in accordance with the invention.

The coatings of Examples 6, 7 and S were tested for the following properties: gloss, hot stacking properties _Jy to determine whether the cured coatings stick to each other or to bare metal and for processing by deformation, to very dust caps for bottles with a firing program to which a 10 minute The plates were fired again at 204 ° C and fired for 30 minutes at 204 ° C. The caps made from the panels were then subjected to 10-minute dry heating at 204 ° C. Another batch of caps made from the panels was subjected to steam heating for one hour

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subjected to a pressure of 2.08 kg / cm at a temperature of 121 ° C. The gloss of the white base coats of Examples 6, 7 and 8 is comparable at an angle of 60 ° in a gloss determination device. At an angle of 20 ° the gloss of Examples 7 and 8 is slightly better than that of Example 6. The hot stack test showed that Example 6 was slightly better than Example 7, while Example 8 was significantly worse than the products of the other examples. After the clear coat was applied over the baked pigmented coating and baked at 163 ° C for 10 minutes, the results of the hot stack test indicated that the product of Example 6 was significantly better than the other two and that Example 7 was better than Example 8, which was unacceptable. After the plate of Example 8 was baked at 204 ° C. for 30 minutes and baked again, the caps made therefrom appeared dull. The properties with regard to the formation of cracks in the lid, defects in the knurling and defects in the body, the base, the notches and elevations in the cap were generally comparable. Caps which had been made from the plates of Examples 6 and 7 fired for 30 minutes at 2O4 ° C. and then subjected to the above-described dry heat test showed traces of cracking in the notched or lip areas. The product of Example 8 failed again in the steaming process, while the products of each of Examples 6 and 7 were satisfactory after treatment, had some bubbles in some cases or their coating was slightly wrinkled when the plate was baked again for 30 minutes. The caps of Example 8 were dull, rusted and had water spots after treatment. The rest of the test results were comparable in terms of processing test , dry heat test and treatment test. .

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In each of the preceding examples, the hardened one had Coating a thickness of about 0.0076 ram to 0.0127 now.

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Claims (12)

Patent claims: 1. Pigmented or non-pigmented thermosetting Compound for coating metals by direct rolling from an alkaline aqueous mixture with a binder, which essentially consists of: A '. a latex of a water-insoluble addition copolymer of (1) 28 to 70% of an aromatic monovinyl manomer, (2) 18 to 68 % of at least one ester of acrylic or methacrylic acid, (3) at least one olefinically unsaturated monomer with at least one amide or one hydroxyl group and (4) an olefinically unsaturated monomer having a carboxyl group, the amount of (3) being from 1.5 to 10 % when the monomer contains an amide group and from 1.5 to 15 % when the monomer contains a hydroxyl group, and the amount of (4) is from 0.5 to 5 % based on the total weight of the monomer, the Tg of the polymer is below 45 and the Gesi
(3) and (4) is 100 and is below 45 and the total amount of (1), (2), B. a water-soluble condensation product of urea or triazine with formaldehyde or its water-soluble methanol or ethanol ether, where the weight ratio of A: B on a particulate basis is from 35:65 to 65:35, the minimum film formation temperature the mass does not exceed about 25 ° C, 409834/1083 the solids content of the mass between 40 and 80 wt. and the mass is from 1 to 5% by weight, based on the solids weight of the mass, of a water-soluble Theological modifier in the form of polyethylene glycol contains. 2. Hasse according to claim 1, characterized in that B a urea-formaldehyde reaction product or a. Melamine-formaldehyde reaction product or its Geraisch. 3. Mass according to claim 1, characterized in that B the reaction product of a urea-formaldehyde adduct with methanol, the molar ratio of urea to formaldehyde to methanol being in the range between 1 / 1.75-3 / 2-3.5, or a melamine-formaldehyde: Adduct with methanol, the molar ratio of melamine to formaldehyde to methanol in the range of 1 / 7-10 / 12-17, or their mixture. H. mass according to claim 3 » characterized in that (1) styrene or vinyl toluene, (2) an ester of at least one acrylic acid and a alkenol having from about 2 to 12 carbon atoms or an ester of methacrylic acid and an alkanol containing about 6 to I ¹ I C-atoms, (3) at least one of the compounds methacrylamide, acrylic r amide, hydroxyethyl acrylate or ethacrylate, or hydroxypropyl acrylate or methacrylate and ( 4) is acrylic acid, methacrylic acid, or itaconic acid. 5 ·. Composition according to Claim 4, characterized in that (1) styrene, (2) butyl acrylate, (3) at least one of the Compounds hydroxyethyl methacrylate and methacrylamide 409834/1083 and (4) methacrylic acid, the corresponding relative amounts by weight of (l), (2), (3) and (4) are in the range up to 28-52 / 40-68 / 1.5-5 / 0.5-2, the total amount being 100 and the composition containing a volatile tertiary amine. 6. Composition according to claim 5 _9, characterized in that the rheology modifier is a polyethylene glycol with a molecular weight of about ¹ 100 to 100,000. 7. Mass according to claim 5, characterized in that they 10 to 20 wt. Jt, based on pesticides in the Contains mass, a liquid organic confluent for the uncured polymer mixture. 8. Mass according to claim 5, characterized in that it contains a pigment, the relative weight of pigment to A + B from 5:95 to 6O: 4o, the Total amount is 100. 9. Composition according to claim 5, characterized in that the proportions of monomers 1/2/3/4 are 35-50 / 45-60 / 1.5-3 / 0.5-2. 10. A method for decorating a substrate, characterized in that the mass of claim 1 rolled directly onto the substrate in an amount providing a final cured layer of 0.00127 to 0.127 mm Thickness results and the coating heated until it is thermoset. 409834/1083 11. The method according to claim 10, characterized in that a metal sheet is used as the substrate and is mechanically deformed after the coating has cured. 12. Process for coating and decorating a metal sheet, characterized in that the sheet is coated with the mass of claim 5 in an amount which has a hardened final layer of 0.00127. to 0.127 now Thickness results, the coating is heated until it is thermoset and the sheet is mechanically deformed. For: Rohm and Haas Company Philadelphia, Pa., V.St.A. Dr.H.J.Wolff Attorney at Law 409834/1083