DE3129230C2 - Process for coating substrates - Google Patents

Abstract

The invention relates to a coating composition which contains the following components: a) a film-forming component of I) a polyepoxide with a 1,2-epoxy functionality of greater than 1.0 and a molecular weight of less than 6000 and II) an amine-containing vinyl copolymer, the Weight ratio of I) to II) is 1:19 to 19: 1, and b) as a catalyst a soluble salt of group II A of the periodic table, the weight ratio of catalyst to film-forming component being 0.1 to 5 parts of catalyst per 100 parts film-forming component lies.

Description

The invention relates to a method of coating of substrates with a coating compound, the film-forming components, catalysts and organic Contains solvent.

Newly manufactured automobiles typically have paints that consist of several layers. The paints give automobiles an aesthetic appearance and protect them at the same time. The ones used today Car paints have a long life, but are occasionally repainted for a variety of reasons of an automobile. Thereby the laceration of the automobile often made in facilities that are not equipped for the use of high curing temperatures and otherwise do not correspond to the facilities of the automobile manufacturers.

There is therefore a desire for a method of repainting automobiles in which the Coating compound at low curing temperatures dries quickly and the paint has the desired properties, such as durability, good appearance and good Liability, confers. In addition, the process should result in an automotive paint that is resistant to organic Solvent, gasoline, moisture and peeling.

The object of the invention is therefore to provide a method for coating substrates / ur, with which one obtains lacquer coatings with the described inherent sounds. According to the invention this The object is achieved by a method for coating substrates with a coating compound which forms the! Contains components, catalysts and organic solvent. This procedure is characterized by that one produces a coating composition by

(a) the film-forming component

(I) a polyepoxide with a 1,2-epoxy functional unit of greater than 1.0 and a molecular weight of less than 6000 and

(II) is an amine-containing vinyl compound, where the weight ratio of (I) to (II) is 1:19 to 19: 1, and

(b) the catalyst is a soluble salt of a metal from Group II A of the Perlode System of the Elements, the weight ratio of catalyst to film-forming component being 0.1 to 5 parts Catalyst is based on 100 parts of film-forming component.

All information about parts, percentages and proportions, which are made when describing the invention are weight specifications, unless expressly stated something else is found.

In a preferred embodiment of the invention, the polyepoxy resins are polyglycidyl ethers of saturated Polyphenols. Polyglycidyl ethers of polyhydric alcohols and polyglycidyl ethers of compounds with a nitrogenous ring. The addition copolymers are preferably derived from an unsaturated carboxylic acid and other mlschpolymerlsicrbaren ethylenically unsaturated monomers from, where 5 to 100'Ί, the pending carboxyl groups with an alkyleneimine are imidlert. Another group of vinyl blend polynes is obtained by reacting a polyamine with aliphatic amine groups and at least an ether group with a polycarboxyl-containing material.

The polyepoxy resin used in the invention has a 1,2-epoxy functionality higher than 1.0 and a Molecular weights less than 6,000. Preferred polyepoxides have molecular weights less than 4,000. One A suitable class of polyepoxides is formed by the polyglycidyl ethers of polyhydric alcohols. Examples of suitable polyhydric alcohols are ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanedlol, 1,2,6-hexanetrlol and glycerin.

Another class of suitable polyepoxides are polyglycidyl ethers of unsaturated polyphenols. These Products are commercially available and can be by reacting a suitable bisphenol with a

Epihalohydrin and subsequent dehydrohalogenation produce. Examples of bisphenol compounds are bis-4 (4-hydroxyphenyl) methane. d. H. Bisphenol F. 1.1 -Bis (4-hydroxyphenyl ethane. 2,2-bis (4-hydroxy-

Phcnyl (propane, ie bisphenol A. and l, l-bis (4-hydroxyphenyl) butane. The 2,2-bis (hydroxyphenyl) propane is preferred. Examples of suitable epilohydrins are epochlorohydrin and epibromohydrin. Suitable catalysts for use in the reaction of the diphenyl compound with the epihalohydrin are tertiary amines, quaternary ammonium hydroxides, quaternary ammonium halides, alkali halides and hydrazines having one tertiary nitrogen atom. In aligemeinen the Dlphenylverblndung with the epihalohydrin at elevated temperatures, for example at 60 is converted to 200 ⁰ C. is for splitting off the hydrogen halide in Usually a strong alkali is used, such as anhydrous sodium hydroxide or a concentrated sodium hydroxide solution.

Other suitable polycapoxy resins are the polyglycidyl ethers of compounds with a nitrogenous ring. These resins are also commercially available, and you can see them by implementing N-heicrocycÜ- Make connections and a Hpihalohydrln. Suitable N-hydrocyclic compounds are 2,4-imidazolledindione (Hydantoin), 5-methyl-2,4-imldazolidinedione. 5.5-I) methyl-2.4-imidazolledione, 5-methyl- : ithyl-2,4-imida / i) lldindlon, 5-ethyl-5-aniyl-2,4-imida / .o-Hdindione, 5-isopropyl-2,4-imidazolledione and 5,5-peniamcylcn-2.4-imida / olidinedione. As lipihalohydrin are also in this case in particular epichlorohydrin and Kpibromhydrln suitable. These polyepoxides and their production are described in US Pat. No. 3,365,471, 3,391,097. 34 50 711. 35 03 979 and in GB-PS 11 72 916 described in more detail.

A preferred class of amine-containing vinyl additive polymers is derived from an ethylenically unsaturated carboxylic acid and at least one other thus from polymerizable and ethylenically unsaturated monomers. Examples of unsaturated Carboxylic acids are acrylic acid and methacrylic acid. Examples of polymerizable ethylenically unsaturated Monomers are alkyl acrylates, such as methyl acrylate, ethyl acrylate, Propyl acrylate, butyl acrylate and isobutyl acrylate; Alkyl methacrylates, such as methyl methacrylate, ethyl methacrylate, Propyl methacrylate, butyl methacrylate and isobutyl methacrylate; and styrenes such as styrene, alpha-methyl styrene and dihalogenated styrenes.

In the invention, preferably aminhaltlge Vlnylmlschpolymere be used which have been prepared from 5 to 30 wt .-% of an ethylenically unsaturated carboxylic acid and 70 to 95 parts by weight ¹ A ₁ at least one ethylenically unsaturated mono- mlschpolymerlslerbaren ^ kidney from the group of alkyl acrylates, Alkyl methacrylates, styrene or mixtures thereof, 5 to 100 mol% of the carboxyl groups of the copolymers having been imidated with an alkylene film. These copolymers particularly preferably contain 10 to 25% by weight of the ethylenically unsaturated carboxylic acid and 75 to 90% by weight of the polymerizable ethylenically unsaturated monomer.

The mixture of monomers is usually polymerized in solution and in the presence of a suitable catalyst. The reaction is usually carried out under controlled elevated temperatures and with stirring. The solution polymerization can be modified in the usual way, for example by adding the mixture of monomers in stages, during the polymerization, by adding the catalyst in portions, by polymerization under a mixed atmosphere and by carrying out the polymerization in a continuous or discontinuous manner.

As a rule, the reaction mixture becomes an organic one Solvent added in order to achieve better handling. It can be of various types Solvents can be used, such as alcohols such as propanol, butanol and other low alcohols Alcohols, ketones such as methyl ethyl ketone, aromatic hydrocarbons such as xylene and toluene and esters such as Butyl acetate. Mixtures of solvents can also be used.

The copolymers containing caiboxyl groups are imidized by reaction with an alkylene film. wherein the alkyleneimine is used in an amount sufficient to contain 5 to 100 mole percent of the carboxyl groups to imidize. Prefers the imidization in the area from 50 to 95 moles * ,. The specified areas of imidization are essential to achieve rapid curing of the coating composition at low temperature. A high level of imidization, for example 200 MoIh, gives a composition with less hardening and also inferior physical properties.

Examples lih suitable alkylene imines: ethylene imine. I.2-Propyhnimine, 1,3-Propylcnimine, 1.1-Dimethylethylcnimine. Phenylethylamine. Tolylethylenelmin. Ben- / ylethyleneimine. 1,2-Diphenylüthylenimin, Hydroxyäthyl- ; it hy Ic η im in. Aminoethylethylminimine. 2-methyl-propylene! min. p-Chlorophenylethylnimine. Methoxyethylethyleneimine. N-Ethylethyleneinin and N-Butylethyleneinin. the preferred alkyleneimines are ethyleneimine and 1,2-propyleneimine.

Another preferred class of amine-containing vinyl addition polymeric polymers is obtained by reaction of a polyamine with aliphatic amine groups and at least one ether group with a polycarhoxyl-containing Material. Such copolymers are characterized in more detail in I) E-OS 30 43 355.7. The backbone The polycarboxyl-containing materials can be made from poly-acrylic compounds. Polyesters or polyamides are made.

The acrylic polymers already mentioned can be used as the backbone. It can also be saturated Polyester resins with pendant carboxyl groups form the backbone of the polycarboxyl compounds. The saturated polyesters are derived from saturated polycarboxylic acids. preferably dicarboxylic acids, and Mixtures of polyhydric alcohols that have an average functionality greater than 2. In the sense of the Invention are aromatic polycarboxylic acids that are only unsaturated in the aromatic ring, saturated acids, because their double bonds do not react under addition. Examples of such acids are phthalic acid. Isophthalic acid, Adipic acid, azelaic acid. Sebacic acid and its anhydrides, as far as they exist. Typical Polyhydric alcohols are ethylene glycol, propylene glycol. Diethylene glycol, dipropylene glycol. Butylene glycol. Glycerine, trimethylolpropane, pentaerythritol and sorbitol.

Other suitable polycarboxyl-containing materials are Polyamide resins. The polyamide resins are obtained in the usual way by condensing a diamond with a Dicarboxylic acid. They contain recurring amld groups of the formula -CONH- In the polymer chain. Examples of suitable diamines are ethylenedlamine. Diethy-

Lentriamln and Hexamethylenediamine- It can use the same dicarboxylic acids as for the production of polyester resins be used, taking adipic acid, sebacic acid. Succinic acid, glutaric acid and azelaic acid are preferred. The equivalent ratio of diamine to dicarboxylic acid varies in the case of the polyamide resins between 1.5: 1 to 1: 2.

The carboxyl content of preferred polycarboxyl-containing materials ranges from 0.5 to 12 Milliequivalents of carboxyl per gram The preferred carboxy content is 1 to 10 milliequivalents of carboxyl per gram.

The ungelled amidification products according to the invention are obtained by reacting the carboxyl-containing Material with a polyamine that contains aliphatic amine groups and at least one ether group. One class of polyamides has the formula

H ₂ N- (C _n R ₀ H _2n -, O) _x -R'- NH ₂

in which π is 2 to 6, σ is 0 to 2, RH, CH, or C ₂ H ₅ , λ is 1 to 60 and R 'is an alkylene radical with 2 to 6 carbon

Atoms of matter 1st. Prefers Hey .v in the range from 1 to 40. Examples of suitable polyamines have the following formulas:

H ₂ NC ₂ H ₄ OC ₂ H ₄ -NH ₂

H ₂ H- (C ₂ H ₄ O) ₁₆ -C ₂ H ₄ -Nh ₂

H ₂ N- (C ₂ H ₄ O) ₂₅ -C ₂ H ₄ -NH ₂

H ₂ N- [CH (CHj) CH ₂ O], - CH ₂ CH (CH,) - NH ₂ H ₁ N- [CH (CHj) CH ₂ O] ₆ -CH ₂ CH (CHj) -NH ₅ H ₂ N- [CH (CH,) CH ₂ O], ₃ -CH ₂ CH (CHj) -NH _:

H ₂ N- (C ₄ H ₈ O) ₁ C ₄ H ₈ -NH ₂

H ₂ N- (CH ₆ O) J-CH ₂ C (CHj) ₂ CH ₂ O-CH ₆ -NH ₂ H ₂ N-CH ₆ OC ₄ H ₈ O-CjH ₆ -NH ₂

Another class of polyamines has the formula: [H ₂ N- (C _n R ₃ H _2n - "O) Jy - Z

where η is 2 to 4, α is 0 to 2. R is R, CH, or C ₂ H, λ is 1 to 60, y is 2 or 3, and Z is alkyl, aryl, or alkylaryl. Preferably, v varies between 1 to 40, and the alkyl or alkylaryi radical contains from about J to 20 carbon atoms. A specific example of such a polyamine is:

H ₂ N- [CH (CH ₃ ) CH ₂ OL-CH ₂

H ₂ N- [CH (CH ₃ ) CH ₂ O] _1. -CH ₂ -CCH 2 CHj, χ + y + ζ = 5.3

H ₂ N- [CH (CH ₃ ) CH ₂ O] - CH ₂

Other suitable polyamines result from the ring opening of a polyepoxide with an ether group with ammonia. Such ungelled reaction products will be referred to here as epoxy resins defunctionalized with ammonia. A suitable class of poly epoxies is made up of the polyglycidyl ethers of the polyphenols. like bisphenol A. Such polyepoxides are obtained by etherification of a polyphenol with epichlorohydrin in the presence of alkali. The phenolic compound can be 1,1 -Bls (4-hydroxyphenyl) ethane, 1.1 -Bis (4-hydroxy-

phenyl! isobutane, 2,2-bis (4-hydroxy-tert-butylphenyD-propane, bis (2-hydroxynaphthyl) methane, 1,5-hydroxynaphthalln and l, l-Bls (4-hydroxy-3-allylphenyI) ethane Another class of polyepoxides can be produced in a similar manner from polyphenol resins.Suitable polyglycldyl ethers are also derived from polyhydric alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanedlol , 1,2,6-Hexantrlol, Glycerin and 2,2-Bls (4-hydroxycyclohexyDpropane. The above-mentioned polyepoxides are reacted with ammonia in the invention. This reaction takes place with a simple ring opening, whereby the product obtained is a polyepoxy resin with a terminal The ammonia used can be aqueous or anhydrous. It is advantageous that essentially all 1,2-epoxy groups of the polyepoxy resin react with ammonia. A molar excess of ammonia over the epoxy groups is therefore used, wherein the molar excess can be 10: 1 or even higher and the unreacted ammonia is removed afterwards. The reaction of ammonia with the Polyepoxldharzes preferably at temperatures of 30 to 10O ⁰ C. The reaction time varies depending on the temperature, but is generally from 2 to 5 hours. The above conditions are desirable in order to prevent further reaction of the primary amine produced with epoxy groups to form highly polymeric or gelled products.

The equivalent ratio of the carboxyl groups and the polyamines is essential to obtain an unsealed product. As a rule, the equivalent ratio of the polyamine to the carboxyl-containing polymer is in the range from 3: 1 to 1: 4, preferably from 1.5: 1 to 1: 1.5. The reaction temperatures and the reaction time can vary widely. Preferably, but operating at a temperature between 25 and 250 ⁰ C, in particular 85 ° to 195 ° C and a reaction time of 0.1 to 48 hours, preferably 0.5 to 8 hours.

The product obtained is an unlabeled amldlertes Polymer that is shelf-stable for long tent spaces. The undellated amidation product contains primary Amine groups, secondary amine groups, or a mixture thereof, and carboxyl groups. The amidation product has an acid number of at least 5, preferably 10 to 500, in particular 15 to 300 and a Amine equivalent of 100 to 5000, preferably 200 to 2000. These products can contain at least 1 at 50.degree Year.

The coating compositions according to the invention contain polyepoxy resins characterized above and an amine-containing vinyl additive polymer. The coating compound contains an organic solvent, and the film former usually consists essentially of the polyepoxy resin and the addition copolymer in a ratio of 1: 19 to 19: 1, preferably 1: 5 to 5: 1.

The content of organic solvent in the coating compositions can be up to 90 "" and is preferred by Hegt at 60 to 80 «,,. Suitable solvents are alkanes, toluene, xylene, naphtha, light gasoline, alkylene glycol monoalky! Ethers, such as ethyl glycol monobutyl ether, ÄthylenglycolmonoilthyÜithcr, Propyleneglycolmonomethyläther and Propyleneglycolmonobutyläther: also Dialkylene glycol monoalkyl ethers, such as ethylene and propylene glycol monobutyl ethers, lower alcohols such as ethanol, isopropanol and butanol, esters such as butyl acetate, Ethyl acetate, ethylene glycol monoethyl ether acetate and mixtures thereof.

The soluble salt of a Group II A metal is In of the coating composition in an amount of 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight per 100 Most of the film-forming component is present. Although higher amounts of catalyst can be used, this usually does not result in any greater catalytic effectiveness. In addition, some properties can be obtained from the coating compositions Films are adversely affected by higher catalyst contents, such as, for example, the durability of the films against moisture. Examples of suitable catalysts are magnesium nitrate, calcium nitrate, Strontium Nitrate, Barium Nitrate, Magnesium Chloride, Calcium Chloride, Strontium Fluorld and Barium Chloride. Magnesium nitrate and calcium nitrate or mixtures thereof are preferred, with magnesium nitrate being particularly preferred Is. In addition, it can generally be stated that the nitrate or halide catalysts of the metals of group II A are particularly suitable to with the film-forming components according to the invention to form low-temperature curable coating compositions.

The coating compositions used in the process according to the invention can, in addition to those already mentioned Components nor additives, such as pigments, dyes, fillers, antioxidants, control agents flow behavior, surfactants and thickeners.

The method according to the invention is preferably used for painting car bodies, but it can also for covering other substrates such as wood. Cement or plastics, serve. The over / u ;: -masses are applied to the substrates in conventional catfish, such as by brushing, rolling, dipping and flowing.

The applied coating masses can be cured within about 36 hours at air temperatures. If desired, the curing time can be shortened by using higher temperatures.

The invention is further illustrated in the following examples explained in more detail.

example 1

The following coating compositions are formulated in order to achieve the advantages of the process according to the invention to demonstrate the coating compositions used in terms of curing time.

continuation

Components (%)

Components (%)

Diglycidyl ether of
2,2-bis (4-hydroxycyclohexyl) propane (1)

Addition Mixing Dolvmeres (2)

8.3 8.3 8.3 8.3 8.3 8.3

15.5 15.5 15.5 15.5 15.5 15.5

> Pigment

(Aluminum flakes)
Ethylene glycol monoethyl ether

ίο naphtha
toluene
Xylene
Magnesium nitrate

Calcium nitrate
Magnesium chloride
Calcium chloride
Magnesium bromide

1.0 1.0 1.0 1.0 1.0

15.2 15.2 15.2 15.2 15.2 15.2

40.0 40.0 40.0 40.0 40.0 40.2

9.0 9.0 9.0 9.0 9.0 9.0

10.8 10.8 10.8 10.8 10.8 10.8 0.2 -

0.2 -

0.2 -

- 0.2 -

- 0.2 -

(1) Commercial product

(2) Copolymer of 53.3% butyl methacrylate, 26.7% styrene and 20.0% methacrylic acid. 95 mol% of the carboxyl groups are imidized with propyleneimine. The mixed polymer has an acid number of 29 and an amine equivalent weight of 515.

The coating compositions are applied to metal sheets in an amount that they dry films with a Form thickness from 45.7 to 53.3 microns. It is checked. Inside which tent non-sticky and non-sticky tape Surfaces are created. An adhesive tape-free surface is understood to mean a surface on which a applied and removed adhesive tape leaves no traces. In addition, the pencil hardness, the durability tested against gasoline and Tuluol after different hardening tents. The gasoline resistance will measured. By putting the coated sheet in gasoline 3 Is immersed for minutes and then the coating is visually determined for cloudiness and softening according to a scale of 1 to 4 is rated, with rating 1 corresponding to high durability. The results of these investigations are summarized below.

43
Coating compound A. B. C. D. E. F. tack-free (min.) 50 40 40 40 40 45 50 tape-free (h) 24 24 24 24 24 48 Pencil hardness (24 h) hardening 2 B TD TD 2 B 3B 4B (168 h) hardening H H H H H F. Gasoline resistance 1 1 1 1 3 3 (48 h) curing (168 h) hardening 1 1 1 1 1 1 Toluene double 30th 30th 35 30th 20th 15th friction ⁵⁰ (168 h) cure

As these results show, they harden in the process coating compositions used according to the invention, d. H. Coating compositions A-E, faster to a tack-free one Condition than the comparative experiment, with the other properties of the films from the invention Coating compounds are comparable or better.

Claims (6)

Patent claims: 1. Process for coating substrates with a coating compound containing the film-forming components, Contains catalysts and organic solvents, characterized in that a coating compound is used manufactures by (a) a film-masking component that (I) a polyepoxide with 1,2-epoxy functionality of greater than 1.0 and a molecular weight of less than 6000 and (II) an amine-containing vinyl copolymer in a weight ratio of (1) to (II) from 1:19 to 19: 1 is, and as a catalyst (b) mixing a soluble salt of a Group II A metal of the Perlodic System of the Elements, wherein the weight ratio of catalyst to film-binding Component at 0.1 to 5 parts of catalyst per 100 parts of film-forming component lies, a substrate is coated with the mixture obtained and the coating is cured. 2. The method according to claim 1, characterized in that the amine-containing vinyl melt polymer has been made from 5 to 30 wt .- '\, one ethylenic unsaturated carboxylic acid and 70 to 95% by weight of at least one polymerizable älhylenlsch unsaturated monomers from the group of alkyl acrylates, alkyl methacrylates, styrene or Mixtures thereof, where 5 to 100 MoK of the carboxyl groups of the copolymer with an alkylene imine Have been implicated. 3. The method according to claim 2, characterized in that the copolymers 10 to 25 wt -% of älhylenisch contains unsaturated carboxylic acid and 75 to 90 wt .- <\, the mischpolymerislerbaren ethylenically unsaturated monomers.. 4. The method according to claim 1, characterized in that the amine-containing vinyl melt polymer an ungelled reaction product of a polyamine with aliphatic amine groups and at least one ether group with a polycarboxylic halogen material Is. 5. The method according to any one of claims 1, 2 or 4, characterized in that the catalyst Magneslumnltrat. Calcium nitrate or a mixture thereof, 6. The method according to claim 5, characterized in that the catalyst is Magneslumnltrat.