DE2701490A1 - THERMAL CURABLE ACRYLIC COPOLYMER - Google Patents

Description

PATENT LAWYERS

M AQQ Dr.-Ing. Wolff

/ AU I * »3 above Bartels

Dipl.-Chem. Dr. Brandes Dr.-Ing. Held Dipl.-Phys. Wolff

8 Munich 22, Thierschstrasse

Tel. (089) 293297

n__ χι- IJC 910 Telex 0523325 (patwod)

Reg. ΝΓ. Mb ZIB telegram address:

~~ wolffpatent, munich

Postal check account Stuttgart 7211

(BLZ 60010070)

Deutsche Bank AG, 14/28630

(BLZ 60070070)

Office hours: 8 a.m. to 12 p.m., 1 p.m. to 4.30 p.m.

except saturdays

11. January 1977 25/2

MITSUBISHI RAYON CO., LTD., 8, Kyobashi 2-chome, Chuo-ku, Tokyo, Japan

Thermosetting acrylic copolymer

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Thermosetting acrylic copolymer

The invention relates to new thermosetting acrylic copolymers, a process for their production and the use of the same as powdery paints or coatings.

It is known, for example, from Japanese Patent Application 32 425/1973, that thermosetting acrylic copolymers with N-alkoxyalkylamide residues as functional, thermosetting residues can be used as powder paints and coatings. the known acrylic copolymers also contain an unsaturated carboxylic acid comonomer having 3 to 5 carbon atoms and one relatively high acidity. The comonomer serves as a catalyst for a crosslinking reaction of the functional groups mentioned of the acrylic copolymer when the copolymer is exposed to heat. When thermosetting a paint is carried out with an acrylic copolymer of the specified type the formation of a coating film by melting and fixing the powdery paint on the substrate and the Cross-linking reaction of the functional groups of the acrylic copolymer together. However, the crosslinking reaction of the functional groups of the acrylic copolymer tends to occur has ended before the powdery particles have melted and film formation has ended. In other words, this means that Cross-links occur as long as powdery particles are still present. Due to the premature emergence of cross-links it is therefore difficult to produce films which have a smooth surface. It has also been shown that the uneven surface of a film applied to a substrate often has very small bubbles. Finally, point with the known copolymers produced films often do not have a sufficiently high resistance to the action of water, corrosions and alkali.

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There has therefore been no lack of attempts to develop a new powdery paint which is free from the disadvantages outlined is.

The object of the invention was therefore to develop a thermally curable paint that can be used as a powdery paint Acrylic copolymers that provide smooth film surfaces. The invention also provided a process for producing suitable ones Acrylic copolymers that can be used as thermosetting copolymers.

In particular, there should be provided a thermosetting acrylic copolymer that can be used as a powder paint and provides films that have a high solvent and Have corrosion resistance.

The invention relates to a thermosetting Acrylcopoly- mer constructed to:

(t) 3 to 30 parts by weight of at least one recurring unit of following formula (I):

(I) Γ ^ ₂ - \ ~

CONHCH ₂ OR ₂

in which R _{1 is} a hydrogen atom or a methyl radical and R _{2 is} an alkyl radical with 1 to 8 carbon atoms or a cycloalkyl radical with 6 to 8 carbon atoms;

(2) 1 to 50% by weight of at least one recurring unit of at least one of the following formulas (II) and (III):

^(II) ir CH ₂ -C ^ h and

COOR ₃ -OOCr ₄ COOH

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COOH (III) -f CH ₂ -C

(CH ₂ ) _n5

in which mean:

R _{1 is} a hydrogen atom or a methyl radical, R, an alkylene radical with 2 to 6 carbon atoms,

Usually an aliphatic, optionally carboxyl radical, radical with 2 to 12 carbon atoms or an aromatic, optionally having a carboxyl radical, radical with 6 to 12 carbon atoms,

Rr is an aliphatic, optionally a hydroxyl group

having, radical with 1 to 18 carbon atoms or an aromatic rule, optionally having a hydroxyl group, Remainder with 6 to 12 carbon atoms and

η * 1 or 2 and

(3) 20 to 96 parts by weight of at least one recurring unit of following formula (IV):

R _lb

- £ CH ₂ -C J X

in which:

Rj. A hydrogen atom or a methyl radical and X is an ester, nitrile or amide radical or a radical of

Formula R ₆ COO-, in which R _{ft represents} an alkyl radical with 1 to 18 carbon atoms, a glycidyl ester, glycidyl ether or an aromatic radical with 6 to 18 carbon atoms or a halogen atom, and which is further characterized

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the polymer has a molecular weight of 4,000 to 30,000 and is in a solid state at normal temperature.

The invention further provides a process for the preparation of a thermosetting acrylic copolymer, which thereby is characterized in that at a pH of 7 or below in Polymerizes in the presence of a catalyst:

(1) 3 to 30% by weight of at least one comonomer of the following formula (I ¹ ):

(I ·) R ₁

CH ₂ -C-CONHCH ₂ OR ₂

in which:

R _{1 is} a hydrogen atom or a methyl radical and R- is an alkyl radical with 1 to 8 carbon atoms or a cycloalkyl radical with 6 to 8 carbon atoms,

(2) 1 to 50 parts by weight of at least one comonomer at least one of the following formulas (II ¹ ) and (III ¹ ):

(II ¹ ) R _la and

CH ₂ -C-COOR ₃ OOCR ₄ COOh

(III ¹ ) COOH

CH ₂ = C

(CH ₇ ),

where mean:

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R _{1 is} a hydrogen atom or a methyl radical, R is an alkylene radical with 2 to 6 carbon atoms,

R. an aliphatic, optionally a carboxyl radical having 2 to 12 carbon atoms or an aromatic, optionally a carboxyl radical with 6 to 12 carbon atoms,

R _{5 is} an aliphatic radical, optionally having a hydroxyl group and having 1 to 18 carbon atoms, or an aromatic radical, optionally having a hydroxyl group, having 6 to 18 carbon atoms and

η = 1 or 2 and
(3) 20 to 96% by weight of at least one comonomer of the formula (IV)

^R 1b
(IV) CH ₂ = CX

where mean:

R-. a hydrogen atom or a methyl radical and

X is an ester, nitrile or amide radical or a radical of the formula R ₆ COO-, in which R _{6 stands} for an alkyl radical with 1 to C atoms or a glycidyl ester radical or a glycidyl ether radical or an aromatic radical with 6 to 18 C atoms or a halogen atom,

until a copolymer having a molecular weight of 4,000 to 30,000 and a solid state at normal temperature is present.

The invention further provides the use of the copolymers described as pulverulent paints.

Acrylic copolymers according to the invention can be prepared, for example, by copolymerizing at least one comonomer of the formula (I ¹ ):

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(I ') R ₁

CH ₂ = C-CONHCH ₂ OR ₂

at least one comonomer of at least one of the following formulas (II ¹ ) and (III ¹ ):

^R 1a CH ₂ = C-COOR ₃ OOCr ₄ COOH and

(III ¹ )

and at least one comonomer of the formula (IV):

< ^IV '> ^R 1b

CH ₂ = CX

where the radicals R ^, R _la , R _lb > R ₂ * ^R 3 » ^R 4» ^R 5 » ^{n uni} * ^{x have} already given meanings.

The radicals of the formula (I) in the acrylic copolymers according to the invention are accordingly derived from comonomers of the formula (I ¹ ).

The comonomer of the formula (I ¹ ) can consist of an acrylamide compound or a methacrylamide compound in which the alkoxy radical OR2 consists, for example, of a methoxy, ethoxy, n-propoxy, n-butoxy, n-octoxy or n-cyclohexoxy radical consists.

Acrylic copolymers which have at least one comonomer of the formula (I ¹ ) in an amount of 3 to 30% by weight, preferably 5 to 20% by weight, have excellent thermosetting properties and melt flow properties when the Copolymers are subjected to a baking or sintering process. If the comonomers or comonomers of the formula (I ¹ ) are used in amounts of less than 3 wt.

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copolymers have poor heat-curable properties. When such comonomers other hand, in amounts of more than 30 wt -.% Is used, so have the low melt flow acrylic copolymers produced on when baking or sintering process. These low melt flow properties are the cause of poor film-forming properties of the acrylic copolymers.

It has proven to be particularly advantageous if R ₂ in formula (I ') is an alkyl radical having 3 to 8 carbon atoms. Such copolymers have particularly advantageous balanced melt flow properties and crosslinking properties during the baking or sintering process.

The radicals of the formulas (II) and (III) in the acrylic copolymers according to the invention are derived from comonomers of the formulas (II ¹ ) and (III ¹ ).

The comonomers of the formula (II ¹ ) can consist, for example, of divalent and trivalent carboxylic acid monoesters of hydroxyalkyl acrylates and hydroxyalkyl methacrylates. The hydroxyalkyl methacrylates contain a hydroxyalkyl group which can consist, for example, of a hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl or hydroxyhexyl group. Hydroxyalkyl radicals having 2 to 6 carbon atoms have proven to be particularly advantageous in the case of the comonomers of the formula (II ¹ ), since this type of comonomers has a particularly advantageous acidity. The divalent and trivalent carboxylic acids can be selected from, for example, divalent and trivalent aliphatic and aromatic

Carboxylic acids exist, for example succinic acid, o-, m-

12 3 4 and p- phthalic acids, Δ -, Δ -, Δ - and Δ -tetrahydrophthalic acids, Hexahydrophthalic acid, naphthalenedicarboxylic acids, trimellitic acid and anhydrides of the aforementioned acids.

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The comonomers of the formula (IIP) can consist, for example, of monoalkyl esters of itaconic acid and of α-methylenepitaric acid.

eg ₁ In the case of the comonomers of the formula (III '), the substituent Rr, / consist of a methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, dodecyl, stearyl or benzyl radical or a radical of one of the following formulas: C ₄ H ₉ -O-CH (OH) -CH ₂ -, HO-CH ₂ CH ₂ -, HO- (CH ₂ ) 3-,

HO-CH ₉ -CH (OH) -CH ₉ -, ^ "Vo-CH (OH) CH ₉ - and C ₁ H ₇ COOCH ₉ -CH (OH) Ch ₉ -.

It has proven to be particularly advantageous if the compound of the formula (II ¹ ) has at least 9 carbon atoms and if the compound of the formula (III ¹ ) has at least 6 carbon atoms, preferably 8 carbon atoms.

The compounds of the formulas (II ¹ ) and (III '} have p.-r-.v * advantageous acidity.

Compared to these compounds, the usual saturated carboxylic acids with 5 carbon atoms or less, for example oleic acid, methacrylic acid, crotonic acid, itaconic acid and α-methylene-glutaric acid, have a relatively high acidity. Accordingly, if these customary unsaturated carboxylic acids are used instead of the special compounds of the formulas (II ¹ ) and (III ¹ ), the acrylic copolymers produced with the N-alkoxyalkylamide group as the crosslinking group have a tendency to terminate the crosslinking reaction before the formation of the coating film from the copolymer Melt is completed as part of the baking or sintering process. As a result, this type of acrylic copolymer does not provide a uniform coating film with a smooth surface. Furthermore, the formation of fine bubbles in the film or coating layer produced cannot be avoided when acrylic copolymers of the type described are used. This leads to coatings and films with poor gloss.

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While the compounds of the formulas (II ¹ ) and (III ¹ ) have a lower acidity than the usual unsaturated carboxylic acids having 5 carbon atoms or less, the radicals of the formulas (II) and (III) in the acrylic copolymers of the invention have sufficiently high acidity to act as a catalyst for a moderately progressive crosslinking reaction of the N-alkoxyalkylamide radicals in the acrylic copolymers can. Accordingly, if a powdery paint with an acrylic copolymer according to the invention is applied to a substrate and then subjected to a baking or sintering process, coatings or films are produced which have no bubbles and have a smooth surface with a pleasing appearance. In addition, the cross-linking reaction can be ended completely during the baking or sintering process. As a result, the coatings or films produced have advantageous chemical and physical properties.

The repeating units of the formulas (II ¹ ) and (III ¹ ) are present in the acrylic copolymers according to the invention in a concentration of 1 to 50 tons by weight, preferably 1 to 30 tons by weight. If the concentration of these residues is less than 1% by weight, the acrylic copolymers produced only have poor heat-curable properties. A content of more than 50% by weight of recurring units of the specified formulas (II ¹ ) and (III ^f ) leads to excessive heat-curable properties of the acrylic copolymers. These excessively high curing properties result in too low melt flow properties of the acrylic copolymers when subjected to the baking or sintering process. Such low melt flow properties also lead to poor chemical properties, for example poor resistance of the resulting coatings or films to the action of water and alkali.

The repeating units of the formula (IV) in the acrylic copolymers of the invention are derived from the comonomers of the formula (IV ¹ ).

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The compounds of the formula (IV) are, for example, acrylates and methacrylates, each with an alkyl or Hydroxyalkyl radical with 1 to 18 carbon atoms; Cyclohexyl acrylates and Cyclohexyl methacrylate; Benzyl acrylates and benzyl methacrylates; Phenyl acrylates and phenyl methacrylates; Vinyl acetate; Vinyl propionate; Acrylamide; Methacrylamide; N-alkyl acrylamides and N-alkyl methacrylamides; Dialkyl acrylamides and dialkyl methacrylamides; N-alkylaminoalkyl acrylates and N-alkylaminomethacrylates; Glycidyl acrylates and glycidyl methacrylate; Methyl glycidyl acrylate and methyl glycidyl methacrylate; Styryl; Vinyl toluene; t-butyl styrene; Vinyl ester the propionic acid and vinyl ester of versatic acid (Versatic acid).

The remainder of the formula (IV) is an essential component of an acrylic copolymer according to the invention for control and monitoring the blocking or blocking properties of the acrylic copolymers, the impact resistance and the resilience against soiling, the effects of chemicals and weathering properties and finally the flexibility and processability of the films and coatings produced.

The content of radicals of the formula (IV) to I part by weight, preferably 20 to 96 at 40 to 96 weight - are \.. In individual cases, the type of the copolymer used or the types of the copolymers of the formula (IV) used can be selected in accordance with the desired properties of the acrylic copolymer to be produced and in accordance with the other types of copolymers to be used.

Acrylic copolymers with 10% by weight have proven to be particularly advantageous or more of at least one comonomer of the formula (IV) in which these comonomers from the aforementioned acrylates and Methacrylates exist because such films and coatings produced have a particularly advantageous resistance to weathering.

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The copolymers according to the invention preferably have a molecular weight of 5,000 to 20,000.

An acrylic copolymer bit less than a molecular weight 4000 designed the production of a film or coating with sufficiently high physical and chemical properties for the practical use difficult. In addition, a powder paint kit of such type of acrylic copolymer is difficult to obtain especially because of the strong tendency to induce the undesirable blocking phenomenon mentioned. On the other hand, from an acrylic copolymer having a molecular weight of more than 30,000, it is difficult to form a coating film having a smooth surface and no entrapped bubbles especially because of the low melt flow properties.

The acrylic copolymers of the invention can be prepared according to the usual ones known methods of solution copolymerization, suspension copolymerization, bulk copolymerization and emulsion copolymerization. As particularly advantageous for In the preparation of the copolymers, suspension copolymerization has proven to be used as copolymers in this copolymerization method of a particularly uniform quality can be obtained, and also because this method of copolymerization can be produced without generating by-products and wastes which can lead to pollution problems. Leave the obtained acrylic copolymers moreover, easily convert into powdery paints.

In preparing acrylic copolymers of the invention by the suspension copolymerization method, the comonomer of formula (I ¹ ). both or one of the comonomers of the formulas (II *) and (III ¹ ) and the comonomer of the formula (IV) are mixed with one another in the stated amounts with a catalyst and optionally a chain transfer agent, whereupon the mixture is subjected to a suspension copolymerization in an aqueous medium with is subjected to a dispersant, whereupon the obtained acrylic copolymer with

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the desired molecular weight and chemical Structure is separated from the aqueous polymerization medium.

The comonomer of the formula (I ¹ ) preferably has a comparatively high degree of hydrophobic properties. This type of comonomers of the formula (I ¹ ) can be copolymerized with high efficiency by the suspension copolymerization process. From this point of view, comonomers of the formula (I ¹ ) with the substituent R ₂ having 3 to 8 carbon atoms have proven to be particularly advantageous.

The acidic comonomers of the formulas (II ¹ ) and (III ') have at least 6 carbon atoms and consequently a suitable degree of hydrophobic properties. Accordingly, the acidic comonomers of the formulas (II ¹ ) and (III ¹ ) can be copolymerized with a high degree of effectiveness to form copolymers according to the invention. For the production of high quality acrylic copolymers using comonomers of the formula (III ¹ ) in high yields by suspension copolymerization, it has proven to be particularly advantageous if the substituent R ^{1 of} the formula (III 1) has at least 3 carbon atoms.

For the production of particularly advantageous acrylic copolymers, it has proven to be particularly advantageous if the sum of the comonomers of the formulas (I ¹ ), (II ¹ ) and (IV *) with a methyl radical as substituents R ₁ , R ^ _a and R .. ^ is at least 10t, based on the total weight of all comonomers of the formulas (I ¹ ), (II ¹ ) and (IV). In this case, the sum of the repeating units of the formulas (I), (II) and (IV) with a methyl radical as substituents R., R. and R., in the case of the copolymers according to the invention, is at least 10 t, based on the total weight of all recurring units of formulas (I), (II) and (IV). Acrylic copolymers of this type lead to powdered paints with a very low blocking property, high resistance to chemicals, dirt and weathering, and excellent processability.

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The polymerization initiator, i.e. the one for carrying out the A catalyst suitable for the process can consist of one of the customary known free-radical polymerization initiators with a comparatively high degree of hydrophobic properties, for example lauroyl peroxide, benzoyl peroxide, azo-bis-isobutyronitrile and azo-bis-valeronitrile.

Suitable chain transfer agents for carrying out the process are in particular the customary known chain transfer agents with a comparatively high degree of hydrophobic Properties such as lauryl mercaptan, octyl mercaptan and thiophenol.

It has proven advantageous to carry out the suspension copolymerization in an aqueous medium at a pH of 7 or less. At such pH values, the comonomers of the formulas (I ¹ ), (II ¹ ), (III ¹ ) and (IV), in particular the comonomers of the formulas (II ¹ ) and (III ¹ ), can be copolymerized with particularly high effectiveness. The aqueous medium for the suspension copolymerization advantageously contains a water-soluble polymeric substance as a dispersant. This water-soluble polymeric substance is said to be effective as a dispersant at pH 7 or below. Such suitable dispersants are, for example, polyvinyl alcohol, partially saponified polyvinyl acetate, carboxymethyl cellulose, starch, gelatin and gum tragacanth. The aqueous medium for the suspension copolymerization can also contain, for example, calcium carbonate, barium sulfate, calcium sulfate, magnesium carbonate, lime, bentonite, diatomaceous earth, sodium sulfate, calcium chloride and sodium chloride as dispersants. In order to keep the pH of the aqueous medium for suspension copolymerization at 7 or below, the aqueous medium may contain an organic or inorganic acid such as boric acid, phosphoric acid, sulfuric acid, hydrochloric acid, acetic acid, formic acid or fatty acids in such Amounts at which the acids do not reduce the activity of the comonomers present in the copolymerization.

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The suspension copolymerization is carried out advantageously at temperatures from 50 to 100 ⁰ C. The acrylic copolymer is obtained in the form of particles or small spheres. In this form, the acrylic copolymers can be separated from the copolymerization mixture by customary known methods, for example by filtering off, salting out and / or centrifuging off. The separated acrylic copolymers can then by customary methods known drying at temperatures of for example 150 ⁰ C or below dried.

An acrylic copolymer made by the process of the invention can easily be converted into a powdery paint and by customary known application methods for powdery paints Apply paints or coatings to a substrate. The powdery paint or the powdery coating composition with the acrylic copolymer can be in aqueous media disperse.

A suitable aqueous medium can contain, for example, a water-soluble solvent, for example one or more Alcohols, glycols, monoacetyl glycols and / or glycol acetate alkoxides or a dispersant consisting of one soluble in water polymeric substance which does not reduce the film-forming properties of the acrylic copolymers, for example an acrylic polymer having carboxylic acid residues and an acid value of 30 or above. The aqueous medium can further optionally be a water-soluble amine or a water-soluble amine compound or Contain ammonia. The powdery paint or coating agent dispersed in the aqueous medium has excellent properties Coating properties.

A powder paint of the present invention has excellent balanced melt flow properties and crosslinking properties Properties on. Accordingly, coatings and topcoat films can be produced with the coating compositions according to the invention which a pleasing appearance, a smooth surface and high resistance to the effects of water and chemicals

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and impact and which further do not have fine air bubbles contain.

In order to further improve the quality of the film or coating produced, the powdery paint also consist of a mixture of the acrylic copolymer and other components, for example an epoxy compound. Beneficial Mixtures are, for example, those made up to 60 to 97% by weight consist of one or more of the acrylic copolymers described and 3 to 40% by weight of an epoxy compound, for example having an epoxy equivalent of 50 to 2000, preferably an epoxy compound which is in the solid state at normal temperature. If the concentration of epoxy compound is increased to over 40% by weight, then the smoothness of the coating or the coating produced may be reduced The film is adversely affected and its chemical and physical properties are reduced.

Advantageously, the epoxy compounds can consist of bis-phenol-A-type epoxy resins, more advantageously Way from condensation products of bis-phenol-A and epichlorohydrin or methylepichlorohydrin; Polyglycidyl esters or polymethylglycidyl esters of polycarboxylic acids, for example terephthalic acid, isophthalic acid, adipic acid and trimellitic acid and triglycidyl isocanurate; Vinyl cyclohexane oxide; Dicyclopentadiene dioxide; and homo- and copo ^ mers of glycidyl acrylates and glycidyl methacrylates and methylglycidyl acrylates and methylglycidyl methacrylates.

The acrylic copolymers described can be used for the production of clear, transparent films and coatings or for the production of colored or pigmented films or coatings. In the latter case, inorganic or organic pigments can be added to the polymers, for example Titanium dioxide, iron oxides, carbon black, phthalocyanine blue and / or phthalocyanine green. Furthermore, the powdery paints according to the invention can optionally melt flow regulators or

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Compounds are added which improve the configuration of the coating surface.

The powdery paint according to the invention can be passed through Prepare spray-drying processes in which, for example, a mixture of an acrylic copolymer and an epoxy compound is dissolved in a solvent, for example a or more alcohols or aromatic solvents, and then the solution is sprayed in the form of fine particles, with evaporation of the solvent and drying of the polymer particles.

A powder paint according to the invention can also be produced, for example, by a method in which, for example, a mixture of an acyl copolymer and an epoxy compound is emulsified in a solvent in a medium which cannot dissolve the mixture, whereupon the emulsified particles of the solution are dried will. It is also possible, for example, to melt a mixture of the type described and knead it uniformly, to cool the kneaded mixture and then to pulverize it. The most advantageous method consists in the fact that it melts and kneads the mixture at a temperature of 50 to 150 ⁰ C, allowed to cool, the kneaded mixture and finely pulverized.

A powdery paint or coating composition with one or more acrylic copolymers according to the invention can be in the form a finely divided powder to be coated by customary known electrostatic powder coating processes or by fluidized coating processes or fluidized coating methods Apply surfaces. Furthermore, however, it is also possible to disperse the powdery paint in an aqueous medium and in the form of a dispersion on the paint to be coated To apply object, for example by an electrostatic powder coating method, by a spray coating method, by a curtain coating method, by a Roll coating method and the like. In an advantageous manner

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become the films or layers applied to the surfaces Baked for 5 to 60 minutes at a temperature of 150 to 250 ° C. A film or coating obtained in this way is one excellent appearance and a smooth surface.

The powdery paint with one or more acrylic copolymers of the type described can be used for coating apply metallic objects, for example made of steel, to objects made of glass, ceramic materials and the like.

The following examples are intended to illustrate the invention in more detail, Example 1

A mixture of 25 parts by weight of methyl methacrylate, 55 parts by weight n-butyl methacrylate, 15 parts by weight of n-butoxymethyl methacrylamide, 5 parts by weight of Z-hydroxyethyl methacrylate monosuccinate of the following Formula:

CH ₃ CH ₂ = C-COOCH ₂ CH ₂ OOCCh ₂ CH ₂ COOH

2 parts by weight of n-octyl mercaptan and 2 parts by weight of lauroyl peroxide were prepared in a kettle, whereupon the air in the kettle was displaced by nitrogen gas. The mixture was then mixed in a mixture of 300 parts by weight of water, 1 part by weight of a partially saponified polyvinyl acetate and 5 parts by weight of sodium sulfate in the kettle. The resulting mixture was then subjected to suspension polymerization in the maintained nitrogen atmosphere at a temperature of 80 ⁰ C. The polymerization time was 4 hours. The obtained acrylic copolymer was separated from the aqueous polymerization medium. The acrylic copolymer had a molecular weight of about 11,000 and an acid number of about 11. The acid number of 11 was the same as the theoretical acid number calculated from the acid values of the comonomers used for the polymerization. The aqueous polymerization medium was analyzed by gas chromatography in order to determine the amounts of comonomers which remained in the aqueous medium.

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ben. As a result, the amount of comonomers remaining in the aqueous medium was very small. From this fact it emerged that the majority of the comonomers present in the polymerization mixture at the beginning of the polymerization process copolymerized to produce the acrylic copolymer.

The acrylic copolymer became fine with a common pulverizer pulverized so that the particles of the acrylic copolymer passed through a sieve with a mesh size of 0.074 mm (200 mesh Tyler standard sieve) could happen.

The fine particles of the acrylic copolymer were then by means of a electrostatic coating device so on the polished The surface of a steel plate of 0.8 mm was applied to form a film having a thickness of 40 y. This film was then baked at a temperature of 200 ° C. for 30 minutes. It was found, that the film produced thereby adhered firmly to the steel plate. In addition, the film was excellent in durability to solvents and showed excellent processability. The film produced also showed a pleasing one Appearance and had a smooth surface that did not contain bubbles.

In a further experiment, 15 parts by weight of an epoxy resin (Epicort 1004, manufactured by Shell Chemical Company) were mixed with 100 parts by weight of the acrylic copolymer to produce a paint mixture. The mixture was then uniformly kneaded in an extruder at a temperature of up to 90 ⁰ C. The mixture was then pulverized using a conventional pulverizer so that the particles of the mixture could pass a sieve with a mesh size of 0.074 mm upset. The film produced was 30 minutes baked at a temperature of 200 ^{° C. for a long time.} The film obtained had a thickness of

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45μ and showed a smooth, shiny surface. The film or the coating was furthermore highly transparent and hard and had an Erichsen value of 5 mm or more. This means that the film produced had excellent mechanical properties.

Example 2

The procedure described in Example 1 was repeated, with the exception, however, that this time 5 parts by weight of monobutyl itaconate used instead of Z-hydroxyethyl methacrylate monosuccinate became. The resulting acrylic copolymer had a molecular weight of about 10,000 and an acid value of about 14. It was in solid state. The acid value given corresponded approximately to the theoretically calculated acid value, which was derived from the acid values of comonomers used was calculated. This in turn shows that almost the entire amount of comonomers with formation of the Acrylic copolymers was topolymerized.

100 parts by weight of the acrylic copolymer prepared in the manner described were mixed with 15 parts by weight of that described in Example 1 Epoxy compound and 57 parts by weight of titanium dioxide mixed. This mixture was then melted in an extruder and kneaded and then finely pulverized so that the particles pass a sieve with a mesh size of 0.074 mm could.

The powder paint obtained was then applied to the surface of a polished steel plate 0.8 mm thick using an electrostatic coating machine. The applied film was baked at a temperature of 200 ^° C. for 30 minutes. The film obtained in this way had a thickness of about 50 µm, was excellent in processing and had a smooth surface. The film formed on the steel plate had a pleasing appearance.

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Example 3 (comparative example)

A mixture of 25 parts by weight of methyl methacrylate, 55 parts by weight of n-butyl methacrylate, 15 parts by weight N-butoxymethyl methacrylamide, 5 parts by weight of itaconic acid, 2 parts by weight of n-octyl mercaptan and 2 parts by weight of lauroyl peroxide were prepared, whereupon the kettle was filled with nitrogen gas. the The mixture was then subjected to suspension copolymerization according to the procedure described in Example 1. The received Acrylic copolymer was then separated from the aqueous copolymerization medium, washed with water and dried. The acid value of the acrylic copolymer was less than 5. As a result, it was found that the acrylic copolymer contained practically no itaconic acid and that most of the itaconic acid used was contained in the aqueous copolymerization medium remained.

The acrylic copolymer was made in a common pulverizer finely pulverized so that the particles could pass a sieve with a mesh size of 0.074 mm. The particles were then applied to the polished surface of a steel plate 0.8 mm thick by means of an electrostatic coating device as also used in the case of Example 1. The applied film was then baked at a temperature of 200 ° C. for 30 minutes. It was found that the film obtained exhibited comparatively poor adhesion to the steel plate, only poor resistance to solvents showed poor soil resistance, and finally exhibited considerably inferior breaking resistance.

Example 4 (comparative example)

A mixture of 25 parts by weight of methyl methacrylate, 55 parts by weight of n-butyl methacrylate, 15 parts by weight of n-butoxymethyl methacrylate, 5 parts by weight of itaconic acid, 0.3 part by weight of azo-bis-isobutyronitrile and 2 parts by weight . parts of n-octylmercaptan was subjected at a temperature of 70 to 80 ⁰ C a bulk polymerization process. The polymerization time was 4 hours.

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«J?

The acrylic copolymer obtained had a molecular weight of approximately 15000 and was in a solid state. The acrylic copolymer became fine using a conventional pulverizer pulverized so that the particles could pass through a mesh sieve with a mesh size of 0.074 mm.

The particles were then on the surface of a polished steel plate a thickness of 0.8 mm using an electrostatic coating device, as also used in Example 1, applied, after which the particles were baked at a temperature of 200 ° C for 30 minutes. The applied film showed a rough surface, poor adhesion properties on the Plate, a comparatively poor workability and a high degree of hardness.

100 parts by weight of the acrylic copolymer described were mixed with 15 parts by weight of the Kpoxyverbindungen described in Befiel 1 mixed, whereupon the mixture was melted and kneaded at a temperature of 100 C. The kneaded mixture was then Allowed to cool and pulverized in such a way that the particles could pass through a sieve with a mesh size of 0.074 mm.

The powder paint thus prepared was then applied to the surface of a polished steel plate and subjected to a baking process as described in Example 1. The obtained film had a suitable degree of hardness and was firmly bound to the plate. However, the film showed a rough surface and an unpleasant appearance.

Example 5 (comparative example)

A mixture of 35 parts by weight of methyl methacrylate, 48 parts by weight N-butyl methacrylate, 12 parts by weight of N-methoxymethyl methacrylamide, 5 parts by weight of methacrylic acid, 2 parts by weight of lauroyl peroxide and 1.5 parts by weight of 2-mercaptoethanol became a solution from 1 part by weight of partially saponified polyvinyl acetate, 5 parts by weight Sodium sulfate and 0.5 part by weight of boric acid in 400 wt.

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Parts of water given. In this way, a mixture of a suspension was prepared which hei a temperature of 8O ⁰ C copolymerization was subjected to 4 hours.

After the completion of the copolymerization, the obtained acrylic copolymer became separated from the copolymerization medium and dried. The dried acrylic copolymer was analyzed for its nitrogen content. It was found that the amount of N-methoxymethyl methacrylamide, which had been polymerized into the acrylic copolymer, was only about 5 (H of the total amount by weight used.

The acrylic copolymer was then converted into a powdery mass and placed on the polished surface of a steel plate as described in Example 1. It was found that this paint with regard to its properties, the paints according to the invention was far inferior.

Example 6 (comparative example)

A mixture of 35 parts by weight of methyl methacrylate, 48 parts by weight of n-butyl methacrylate, 12 parts by weight of N-methoxymethyl methacrylamide, 5 parts by weight of methacrylic acid, 0.3 part by weight of azo-bis-isobutyronitrile and 1, 5 parts by weight of 2-mercaptoethanol was subjected to a copolymerization in the mass at a temperature of 70 to 8O ⁰ C. The copolymerization time was 4 hours. The obtained acrylic copolymer was obtained in a solid state and had a molecular weight of about 8,000.

100 parts by weight of the solid acrylic copolymer was mixed with 15 parts by weight the epoxy compound described in Example 1 and 57 parts by weight Titanium dioxide mixed. The mixture was melted and kneaded by means of an extruder, and then made into a powdery one Transferred mass according to the method described in Example 1. The powder paint obtained was then used for coating the surface of a polished steel plate with a thickness of 0.8 ram is used. The coating was carried out by means of an electro-

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static coating device. The film applied to the steel plate was then baked at 20 ° C. for 30 minutes. The film thus obtained had suitable hardness and high adhesive strength to the plate. Her film, however, had comparatively poor workability. In those cases where the thickness of the film produced was over 50%, numerous vesicles occurred in the film, and the surface of the film was rough as a whole. As a result, had di t coating produced an unsightly appearance.

Example 7

The procedure described in Example 5 was repeated with the exception, however, that this time 5 parts by weight of 2-hydroxyethyl methacrylate monophthalate of the following formula:

CH ₂ = C-COOCH ₂ Ch ₂ -OOC '^ COOH

were used in place of methacrylic acid. The film applied to a polished steel plate was ^{baked at 200 °} C. for 30 minutes. The film obtained had an advantageous hardness, a high adhesive strength on the substrate and a high resistance to breakage. Even when the thickness of the film was over 50μ, the surface of the film was found to be smooth and glossy. The coating obtained had a pleasing appearance.

Example 8

A mixture of 37 parts by weight of methyl methacrylate, 46 parts by weight of tridecyl methacrylate, 10 parts by weight of n-butoxymethyl methacrylamide, 7 parts by weight of 2-hydroxyethyl methacrylate monosuccinate, 1 part by weight of azo-bis-dimethylvaleronitrile and 2 parts by weight n-Octyl mercaptan is produced, whereupon the air from the boiler was displaced by nitrogen gas. The mixture then became a solution of 1 part by weight of a partially saponified polyvinyl acetate and 6 parts by weight of sodium sulfate in 300 parts by weight of water.

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The mixture obtained was then kept at a temperature of 70.degree copolymerized in the suspension. IHe copolymerization time was 4 hours. The obtained acrylic copolymer was separated from the aqueous copolymerization medium and dried. as As a result of a nitrogen analysis and an analysis for determining the acid value, it was found that the total amount of N-butoxymethyl methacrylamide and the comonomers having a carboxylic acid group reacted to the acrylic copolymer by the copolymerization had been. The acrylic copolymer had a molecular weight of about 12,000 and was in a solid state.

100 parts by weight of the acrylic copolymer described were with 10 parts by weight of the epoxy compound also used in Example 1 and 55 parts by weight of titanium dioxide mixed. The mixture was at melted and kneaded at a temperature not exceeding 100 ° C. The resulting mixture was then put in a conventional pulverizer pulverized in such a way that the particles of the mixture pass through a sieve with a mesh size of 0.083 mm (180 mesh the Tyler standard sieve series).

The prepared paint was then used to coat the surface of a polished steel plate 0.8 mm thick, again using an electrostatic coating device. The applied mass was then baked ^{at a temperature of 200 ° C. for 30 minutes.} The film produced in this way had a very pleasing appearance, exhibited a smooth surface, strong adhesion to the plate and excellent processing properties. Incidentally, the film was excellent in corrosion resistance.

Example 9

30 parts by weight of the powder paint with the acrylic copolymer and the epoxy compound, prepared as described in Example 1, were added to 70 parts by weight of water adjusted to a pH of 11 by ß-dimethylaminoethanol had been suspended. The suspension produced was 24 hours

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treated for a long time in a ball mill to uniformly pulverize the paint and disperse it in water. A uniform aqueous dispersion of the powder paint was obtained. The aqueous dispersion was then applied to the surface of a polished steel plate by spraying it with a spray gun. The sprayed-on material was then dried and ^{baked at a temperature of 200 °} C. for 30 minutes. In this way, a holding film with a smooth surface was obtained.

Example 10

Following the procedure described in Example 1, an acrylic copolymer was obtained starting from a mixture of 15 parts by weight of hydroxyethyl methacrylate monosuccinate, 22 parts by weight of methyl methacrylate, 60 parts by weight of n-butyl methacrylate, 10 parts by weight of n-butoxymethylacrylamide, 2.0 parts by weight of azo-bis-isobutyronitrile and 2 parts by weight of n-octyl mercaptan.

20 parts by weight of the acrylic copolymer were mixed with 78 parts by weight of water containing 2 parts by weight of dimethylaminoethanol. The mixture was then placed on a shaker and shaken for 1 week. In this way it became a water-soluble one Copotyn mass obtained. 25 parts by weight of this water-soluble The mass was mixed with 50 parts by weight of the same powdery paint containing the acrylic copolymer and the epoxy compound, as described in Example 1 and mixed with 25 parts by weight of water.

The mixture thus prepared was then placed in a ball mill and milled therein for 24 hours. In this way, an aqueous paint was obtained in which the powder paint was uniformly dispersed. The aqueous paint was applied to the surface of a polished steel plate by means of a spray gun and dried. AnxKkixKfiiick The sprayed-on material was then

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rial baked for 30 minutes at a temperature of 22O ⁰ C. In this way, a film having a smooth surface and a pencil hardness of 2H and an Erichsen value of 6 mm was obtained.

Example 11

Following the procedure described in Example 1, a solid Acrylic copolymer with a molecular weight of 9,000 by suspension polymerization of 45 parts by weight of methyl methacrylate, 25 parts by weight of tridecyl methacrylate, 5 parts by weight of n-butoxymethyl methacrylamide and 0.25 part by weight of 2-hydroxyethyl monophthalate in the presence of 3.0 parts by weight of n-octyl mercaptan and 2.0 parts by weight of lauroyl peroxide.

To produce a powdery paint, 100 wt. Parts of the acrylic copolymer prepared in the manner described with 20 parts by weight of an epoxy compound (Epicort 1002, manufacturer Shell Chemical Company), 60 parts by weight of titanium dioxide and 2 parts by weight of tridecyl methacrylate copolymer mixed, whereupon the mixture was melted and kneaded in an extruder.

The mixture produced in this way was then pulverized in a conventional pulverizer in such a way that the particles of the mixture obtained could pass through a sieve with a mesh size of 0.074 mm. The powder paint obtained was then applied to the surface of a polished steel plate of a thickness of 0.8 mm by means of an electrostatic coating device, whereupon the applied particles were baked ^{at a temperature of 200 ° C. for 30 minutes.} The film produced in this way had a thickness of 40μ, a gloss value of 85 or more, and was excellent in processing. Otherwise, the film produced had a pleasing appearance.

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Example 12

A solid acrylic copolymer with a molecular weight of 11,000 starting from 45 parts by weight of styrene, 40 parts by weight of tridecyl methacrylate, 10 parts by weight of N-butoxymethyl methacrylamide and 5 parts by weight of 2-hydroxyethyl methacrylate monosuccinate was obtained by bulk polymerization produced by 2.0 parts by weight of azobisisobutyronitrile and 2.5 parts by weight of n-octyl mercaptan at a temperature of 70 to 90 ⁰ C. The polymerization time was 8 hours.

100 parts by weight of the acrylic copolymer prepared in the manner described were mixed with 10 parts by weight of the epoxy compound described in Example 1 and with 55 parts by weight of titanium dioxide. The mixture was then melted and kneaded in an extruder. The mixture was then converted into a powdery paint in the manner described in Example 1. With this, the surface of a polished steel plate of a thickness of 0.8 mm by means of an electrostatic coater, were baked for 30 minutes after which the coated particles at a temperature of 22O ⁰ C. In this way, a film having a thickness of 45 µm with a pencil hardness of 2H and excellent workability was formed on the steel plate. The film produced also had a pleasing appearance.

J 709830/0835

Claims (1)

270H90 PATENT CLAIMS 1. Thermosetting acrylic copolymer built up to: (1) 3 to 30 parts by weight of at least one recurring unit of the following formula (I): (I) -ecH ₂ - c - * - CONHCH ₇ OR ₉ in which R 1 denotes a hydrogen atom or a methyl radical and R ₂ denotes an alkyl radical having 1 to 8 carbon atoms or a cycloalkyl radical having 6 to 8 carbon atoms; (2) 1 to 50% by weight of at least one repeating unit at least one of the following formulas (II) and (III): (II) ~ f " ^CH 2 ~ ^C ~~} ^and COOR ₇ -OOCR.COOH 3 4 COOH (III) -e CH ₂ -C ^ - WtW'y) LUUKr ^ nw
in which mean: R .. a hydrogen atom or a methyl radical, Rj an alkylene radical with 2 to 6 carbon atoms, R ^ an aliphatic, optionally having a carboxyl radical, radical with 2 to 12 carbon atoms or an aromatic radical with 6 to 12 carbon atoms, optionally containing a carboxyl radical, 709830/0885 originally inspected 270H90 R _{5 is} an aliphatic radical with 1 to 18 carbon atoms, optionally containing a hydroxyl group, or an aromatic radical, optionally containing a hydroxyl group, with 6 to 12 carbon atoms and η = 1 or 2 and (3) 20 to 96 parts by weight of at least one recurring unit of the following formula (IV): (IV) i ^1b -t CH ₉ -C -f- in which: R ₁ , a hydrogen atom or a methyl radical and X is an ester, nitrile or amido radical or a radical of the formula RgCOO-, in which R is an alkyl radical with 1 up to 18 carbon atoms, a glycidyl ester, glycidyl ether or aromatic radical with 6 to 18 carbon atoms or a Represents halogen atom, with the proviso that the polymer has a molecular weight of 4,000 to 30,000 and is in the solid state at ordinary temperature. 2. Acrylic copolymer according to claim 1, characterized in that the sum of the repeating units of the formulas (I), (II) and (IV) with a methyl radical as substituents R «, R- and R ... is at least 101 based on the total weight of all repeating units of formulas (I), (II) and (IV) in the acrylic copolymer. 3. Acrylic copolymer according to claim 1, characterized in that the substituents R ₂ in formula (I) consist of alkyl radicals having 3 to 8 carbon atoms. 709830/0885 270H90 4. Acrylic copolymer according to claim 1, characterized in that the substituents Rr in the formula (III) from aliphatic Residues with 3 to 18 carbon atoms and optionally a hydroxyl group or from aromatic residues with 6 to 18 carbon atoms, optionally with a hydroxyl group. 5. Acrylic copolymer according to claim 1, characterized in that the substituents R ₂ in the formula (I) consist of alkyl radicals having 3 to 8 carbon atoms and the substituents R ₅ in the formula (III) consist of aliphatic radicals having 3 to 18 carbon atoms and optionally a hydroxyl group or aromatic radicals with 6 to 18 carbon atoms and optionally a hydroxyl group. ' 6 / Process for the production of a thermosetting acrylic copolymer according to Claims 1 to 5, characterized in that that in the presence of a catalyst: (1) 3 to 30% by weight of at least one comonomer of the formula (Y) (I ·) CH ₂ = C-CONHCH ₂ OR ₂ where Rj represents a hydrogen atom or a methyl radical and Rj ^e ^ ^{n is an} alkyl radical with 1 to 8 carbon atoms or a cycloalkyl radical with 6 to 8 carbon atoms, (2) 1 to 50 wt -% of at least one comonomer at least one of the following formulas (II ¹⁾ and (III ^1).: (II ¹ ) CH ₂ -C-COOR ₃ OOCr ₄ COOH and (III ¹ ) CH ₂ = C COOH (CH ^ COOR ₅ 709830/0885 270U90 where mean: R _{1 represents} a hydrogen atom or a methyl radical, R 1 is an alkylene radical with 2 to 6 carbon atoms, R _{4 is} an aliphatic radical with 2 to 12 carbon atoms and optionally a carboxyl radical or an aromatic radical with 6 to 12 carbon atoms and optionally a carboxyl radical and R _{5 represents} an aliphatic radical with 1 to 18 carbon atoms and optionally a hydroxyl group or an aromatic radical with 6 to 18 carbon atoms and optionally a hydroxyl group and η is a number of 1 or 2 and (3) 20 to 96% by weight of at least one comonomer of the following Formula (IV): (IV) CH ₂ -CX wherein R .. is a hydrogen atom or a methyl radical and X is an ester, nitrile or amido radical or a radical of the formula R ₆ COO- wherein R ₆ is an alkyl radical having 1 to 18 carbon atoms, a Glycidylesterrest, a Glycidylätherrest or an aromatic radical with 6 to 18 carbon atoms or a halogen atom, to a copolymer having a molecular weight of 4,000 to 30,000, which is in the solid state at normal temperature, copolymerized. 709830/0885 270H90 7. The method according to claim 6, characterized in that the catalyst used is a hydrophobic radical polymerization initiator. 8. The method according to claim 6, characterized in that the comonomers of the formulas (I ¹ ), (H ') and (IV ¹ ) are selected in such a way that the sum of these comonomers with a methyl radical as substituents Rj, R. and R. , at least 10%, based on the total weight of all comonomers of the formulas (I ¹ ), (II ¹ ) and (IV). 9. The method according to claim 6, characterized in that monomers of the formula (I ¹ ) are selected in which R _{2 is} an alkyl radical having 3 to 8 carbon atoms. 10. The method according to claim 6, characterized in that monomers of the formula (IIΓ) are used in which the substituent R ₅ consists of an aliphatic radical having 3 to 18 carbon atoms or an aromatic radical. 11. The method according to claim 6, characterized in that one ^{selects monomers of the formula (I f} ) in which the substituent R- is an alkyl radical with 3 to 8 carbon atoms and that one further Selects monomers of the formula (III ¹ ) in which the substituent R ₅ consists of an aliphatic radical with 3 to 18 carbon atoms or an aromatic radical. 12. The method according to claim 6, characterized in that one adding a conventional molecular weight regulator to the polymerization mixture for the purpose of controlling the molecular weight. 13. The method according to claim 6, characterized in that the copolymerization is in the form of a suspension polymerization carried out in an aqueous medium at pH 7 or below. 709830/0885 270U90 14. The method according to claim 13, characterized in that there is used an aqueous medium which is soluble in water polymeric substance or an inorganic compound. 15. Use of a thermosetting acrylic copolymer according to Claims 1 to 5 as a powder coating. 16. Use of an acrylic copolymer according to claim 15 in a mixture with 3 to 40% by weight of an epoxy compound having an epoxy equivalent of 50 to 2000. 17. Use of an acrylic copolymer according to claims 1 to 5 in the form of a suspension in an aqueous medium. 18. Use of a thermosetting acrylic copolymer according to claims 1 to 5 as a powdery paint by melting and kneading the acrylic copolymer with an epoxy compound at a temperature of 150C or below, cooling the kneaded mass and pulverizing the cooled mass. 709830/0885