JP2536855B2 - Reactive rackers for producing coatings, basecoats, basecoats and spray-stoppers, and methods for obtaining coatings, basecoats, basecoats and spray-stops - Google Patents

Description

TECHNICAL FIELD The present invention relates to (A) a hydroxyl group-containing copolymer, (B) an epoxy resin, (C) a polyisocyanate as a curing agent, (D) an inert organic solvent, and Optionally (E) a reactive lacquer for the production of coatings, basecoats, basecoats and spray bases, obtained by mixing the reactive lacquer with other customary additives, And coatings, base coats, base coats and spray coats, lacquers based on hydroxyl group-containing compounds, polyisocyanates, solvents and optionally customary additives on the support and at room temperature or up to 80 ° C. It relates to a method obtained by curing at elevated temperature.

BACKGROUND OF THE INVENTION As is well known, automotive reactive lacquers and automotive repair reactive lacquers based on acrylics and polyisocyanates are known, for example, from West German Patent 285809.
No. 6, 2858097 and 2858105, in terms of good gloss life and in rare gasoline, detergent stability and surface curing of coated lacquers. It has extremely favorable properties.

However, there is a need for improvement in the primer applied when applying automotive repair lacquers to steel sheet substrates. Conventional basecoats are based on fast-drying polyesters, but the coatings obtained thereby have poor corrosion resistance. Moreover, the adhesion between polyester base and reactive lacquer finishes needs to be improved.

Means for carrying out the invention: The object of the invention is to provide such a reactive lacquer of the aforesaid type, which has the following properties, and thus produces a positive astonishing effect in a number of directions.

1. The coating agent, in the form of a primer, shows a pronounced adhesion to steel, aluminum and zinc and also an improved adhesion to the applied coating lacquer.

2. Coatings of the type described above are strong-stopping basecoats and spray-stoppers, which may be chromate-free and have fast-drying and polishing potential after application.

3. Coating agents of the type mentioned above give a corrosion-resistant primer with good corrosion resistance after application, in which case the adhesion of the metal to the substrate is not impaired by the action of water.

4. Coating agents of the type described above give dry films after a relatively short time.

5. The coating applied in the form of a primer achieves a dryness of 3 with a dry layer thickness of about 50μ after a drying time of 25 minutes at 25 ° C.

6. Coatings applied in the form of a primer show no bubble formation or rust after a drying time of 5 days at 25 ° C and subsequently in a salt spray test according to ASTM 117-64 after 240 hours of loading. . Even when the basecoat is mechanically exposed with a knife, no small bubbles or rust are visible.

7. In the case of coatings applied in the form of a primer, on steel sheets, aluminum sheets and zinc sheets at constant climatic conditions at 40 ° C. and 100% relative air humidity in a condensed water test according to DIN 50017, No bubble formation is present after a test time of 25 days (600 hour load).

8. The binder mixture results in an air-dried basecoat in combination with a polyisocyanate, which basecoat compensates the customary basecoat in the case of automotive lacquer application and after subsequent drying. Compensate for applying conventional lacquer eye-stops. This means that the novel basecoating agent obtained with the binder according to the invention is applied on the metal surface in the spraying process and has hitherto been applied twice with the basecoating (dry) and the lacquer basement agent. It means that what you have done becomes useless.

9. Another advantage is that the same polyisocyanates can be used for basecoats and subsequently applied two-component reactive lacquers based on acrylic resin-polyisocyanates, which makes them outstanding. Adhesion and corrosion resistance are achieved.

10. The basecoating agent according to 8. above can be polished already after 30 minutes.

11. The binder mixture, in combination with polyisocyanate, has a layer thickness of up to 200 μ, as a coating layer filling agent at 60 ° C. 3
It exists dry in 0 minutes and thus a rapid work progress is achieved in the lacquering plant.

12. The binder mixture is storage stable despite the presence of carboxyl groups in the copolymer resin and epoxy groups in the epoxy resin. This means that only a negligible increase in viscosity occurs on storage of the binder mixture.

The component (A) present as a copolymer is a vinyl compound polymerization initiator (either alone or in a mixture) by a method known per se.
Is obtained by polymerizing in an inert organic solvent in the presence of.

In one preferred embodiment for obtaining the copolymer, an inert organic solvent having a boiling range of about 120 ° C. to about 180 ° C. is heated to boiling under an inert protective gas to produce a vinyl compound monomer. The mixture is copolymerized in the presence of at least one polymerization initiator, preferably two polymerization initiators, in the course of 2 to 8 hours, preferably 4 to 6 hours, with gradual addition of the mixture, the water of reaction being , Is continuously removed from the boiling reaction batch by azeotropic distillation, returning the anhydrous distillate. After the vinyl monomer has been added, the vinyl monomer is polymerized and further polymerized for a long period of time until it is present.
3.5 to 5 hours are required.

As polymerization initiators, for example, the following can be used alone or in a mixture: diacyl peroxide,
Ketone peroxide, alkyl hydroperoxide, alkyl perester such as benzoyl peroxide,
Hydroxyheptyl peroxide, 1-hydroxycyclohexyl peroxide, tert-butyl perbenzoate, tert-butyl peroxide octoate, di-tert-butyl peroxide and all peroxides with a half-life within the temperature range of 50 ° C to 150 ° C.

The preferred embodiments include the following peroxide combinations: dibenzoyl peroxide-cumol hydroperoxide; dibenzoyl peroxide-di-tert-butyl peroxide; tert-butyl peroctoate-cumol hydroperoxide; Tributyl peroctoate-di-tertiary butyl peroxide; Tertiary butyl perbenzoate-cumol hydroperoxide and tertiary butyl perbenzoate-di-tertiary butyl peroxide.

As component (B), an epoxy resin based on the reaction product of epichlorohydrin and bisphenol A having an epoxy number of about 400 to about 600 is used.

The binder mixture is a solution of component (A) and component (B).
Solution in an inert organic solvent, sometimes 80 ° C to 90 ° C.
Obtained by mixing while heating to ° C.

Polyisocyanates are used to cure the binder mixture. Examples are: 3,5,5-trimethyl-1-cyanate-3-isocyanatomethylcyclohexane, di (2-isocyanatoethyl) bicyclo- (2,2,1) hept-5-ene-2 , 3-dicarboxylate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, 4,4 'diphenylmethane diisocyanate, dianisidine diisocyanate, toluidine diisocyanate, hexamethylene diisocyanate, dicyclohexyl-4,4'- Methane diisocyanate, cyclohexane-1,4-diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diisocyanate diphenyl ether, 2,4,6-toluene isocyanate, triphenylmethane-4,4 ', 4 " -Triisocyanate, ethylene diisocyanate, propylene diisocyanate , Tetramethylene diisocyanate, hexamethylene diisocyanate, 1,3-dimethylbenzol diisocyanate, 1,4-dimethylcyclohexane diisocyanate, 1-methylcyclohexane-2,4-diisocyanate, 4,4'-methylene-bis (cyclohexyl diisocyanate) Phenylene diisocyanate,
Naphthylene diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, lysine diisocyanate, triphenylmethane triisocyanate, trimethylbenzol-2,4,6-triisocyanate, 1-methylbenzol-2,4,6 -Triisocyanates and diphenyl-2,4,4'-triisocyanates; polyisocyanates containing low molecular weight diols or triols (e.g. ethylene glycol, propylene glycol, 1,3-butylene glycol, neopentyl glycol, 2,2,4- Diisocyanates or triisocyanates obtained by reaction with trimethyl-1,3-pentadiol, hexanediol, trimethylolpropane or trimethylolethane); Cyanurate obtained by reacting with.

Particularly important polyisocyanates are triisocyanates containing biuret groups, obtained by reacting from 3 mol of diisocyanate and 1 mol of water,
For example hexamethylene diisocyanate or 4,4'-
It is a biuret of methylene-bis (cyclohexyl isocyanate) or 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate. Also,
Also suitable are polyisocyanates obtained by ring closure of heterocycles from 3 mol of diisocyanates, for example hexamethylene diisocyanate.

Further, instead of polyisocyanate, a compound which separates polyisocyanate can be used, and further, a polyhydric alcohol such as ethylene glycol, propylene glycol, hexanediol, trimethylolpropane or trimethylolethane, and an isocyanate group of polyisocyanate can be used. It is possible to use reaction products containing, for example, the reaction product of 1 mol of trimethylolpropane and 3 mol of toluylene-diisocyanate, and further to use, for example, terephthalic acid as described in West German Patent 951168. Isomerized or polymerized isocyanates can be used.

If desired, curing of the binder mixture with polyisocyanate as a curing agent can be facilitated by adding a curing catalyst. Suitable curing catalysts for this purpose are stannous acylates or stannous alkoxides which may be substituted by hydroxyl, halogen, keto or other groups which do not adversely influence the curing reaction. . Stannous acylates that can be used as the curing catalyst component include divalent tin salts of monocarboxylic acids and dicarboxylic acids having 1 to 54 carbon atoms; the carboxylic acids include saturated acids such as acetic acid. , 2-ethylhexanoic acid, ethylphthalic acid and unsaturated acids such as oleic acid, linoleic acid, oleostearic acid,
It can be ricinoleic acid or the like. For clarity,
Suitable stannous acylates include stannous acetate, stannous propionate, stannous acid, stannous butyrate, stannous tartrate, stannous valerate, stannous octoate, stannous stearate. Examples thereof include stannous tin, stannous oleate, and dibutyltin dilaurate. The stannous alkoxides that can be used as curing catalysts include the divalent tin salts of saturated or unsaturated straight or branched chain alcohols having 1 to 18 carbon atoms. Examples of suitable stannous alkoxides for this purpose are stannous methoxide, stannous isopropoxide, stannous butoxide, stannous t-butoxide,
Stannous-2-ethyl-hexoxide, stannous tridecanoxide, stannous heptadecanoxide, stannous phenoxide and o-stannous cresoxide, m-stannous cresoxide and p-stannous cresoxide.

Coatings containing a binder mixture of components (A), (B) and a polyisocyanate as curing agent are known for formulations containing the various required components in the required amounts of the reaction components. Obtained by mixing thoroughly after control and used.

The total amount of isocyanate groups in the coating is sufficient to allow the isocyanate groups to react with the reactive hydrogen atoms present at the beginning of curing or formed during the course of the curing reaction. There must be.

0.5-1.10 equivalents per reactive hydrogen atom, especially 0.8-
1.05 equivalents of isocyanate are used.

The concentration of stannous salt in the coating agent is from 0.1 to 10% by weight, based on the weight of the binder mixture and the polyisocyanate, especially
It can be between 0.5 and 2% by weight.

In producing the copolymer (A), an inert organic solvent is used alone or in a mixture, and the inert organic solvent can be adjusted to a desired boiling range of about 120 ° C to about 180 ° C. Moreover, it is suitable for holding the copolymer (A) in a solution, and in the case of producing a binder mixture, a solution without turbidity can be obtained by adding the epoxy compound as the component (B). Examples for this are aromatic solvents as well as esters having a boiling point of 120 ° C to about 180 ° C.

If the reactive lacquer coatings are prepared by mixing the binding mixture with polyisocyanates and the usual constituents customary for the production of basecoats, basecoats and spray bases, the lacquer industry is likewise used. In conventional organic solvents are used together, the boiling point of which is essentially low in order to achieve rapid drying by evaporating the solvent in the curing reactive lacquer coating. Can be made.

In addition, the nitrocellulose solutions customary in the lacquer industry in inert organic solvents belong to the constituents customary for the production of basecoats, basecoats and spray bases.

Examples: Next, the present invention will be described in detail with reference to Examples.

Production of Copolymer 1 mC₉140 ° C. to 160 ° C., containing 80% aromatic compounds
Aromatic solvent mixture with boiling point of 940g (Shell Sol (Sh
ellsol ) A) together with 450 g of ethyl glycol acetate, a stirrer,
Thermometer, reflux condenser with water separator and inert gas
Heat to 160 ° C. in a reaction vessel equipped with an inlet tube.

Methyl methacrylate 610 g Hydroxyethyl methacrylate 997 g Styrol 990 g Acrylic acid 43 g n-Butyl acrylate 70 g and diben dispersed or dissolved in water at 75%
Mix a mixture of 70 g of zoyl peroxide for 7 hours.
Add in. The distillation temperature is 15 during the feeding of the monomer mixture.
Reduced to 0 ° C. Then, after 5 hours of further polymerization,
A solids content of 70% by weight in the agent mixture is obtained. Viscosity
In order to measure, the copolymer solution was mixed with a commercially available volume ratio of 2: 1.
Aromatic solvent Shellson ) A (Shell company
(Shell) in the company newsletter (Shellsol
) A) and 60% by weight with ethyl glycol acetate
To dilute. The viscosity is 1500-1800 mPa.s at 20 ° C.
The acid value of the copolymer as a solid resin takes a value of 11 to 13,
The hydroxyl number of the solid resin is 120.

Reference Example 1: Preparation of Binder Mixture 1 2500 g of Copolymer 1 at 90 [deg.] C., reaction formation from epichlorohydrin and bisphenol A having an epoxy value of 450-530 and 70% dissolved in xylol. Object-based epoxy resin 23
Hold with 20g at 90 ° C for 1-2 hours. The following characteristic values are obtained for the binder mixture solution: 72% by weight solids content, binder mixture-solid resin acid number 7, binder mixture-solid resin hydroxy number 200-230.
The viscosity of the binder mixture 1 is 13000 to 15000 mPa.s at 20 ° C.

The viscosity measurements described above very clearly show that upon storage at 50 ° C. only a slight increase in viscosity occurs after 20 days. This means that the binder mixture is storage stable and produces a negligible increase in viscosity when stored at external temperatures despite the presence of carboxyl groups in the copolymer resin and epoxy groups in the epoxy resin. To do.

Production of Copolymer 2 The copolymer is produced by the same method as that described above when producing the copolymer 1. The numbers listed in Table II below are for weight percent. Unlike the solvent mixture used to produce Copolymer 1, when Copolymer 2 is produced, work is done as described in Table III.

The above tests show that the binder mixture is just storage-stable in the absence or presence of catalyst, even at elevated temperatures. This means that during normal storage of the binder mixture, only a negligible increase in viscosity occurs at external temperature.

All entries in Table V above mean weight percent.

Use example 1 illustrates the preparation of a parent lacquer as a basecoat. The parent lacquer is mixed with a polyisocyanate-based curing agent solution, adjusted to the processing viscosity required for the coating technique used in inert organic solvents, and applied as a base-coating agent on metal surfaces. It

A special test of the basecoat or the basecoat-coating obtained according to Use Example 1 revealed that the object of the invention was realized in such a way that it could be easily implemented in practice.

Claims (3)

(57) [Claims] 1. Conventionally used in (A) hydroxyl group-containing copolymer, (B) epoxy resin, (C) polyisocyanate as a curing agent, (D) inert organic solvent and optionally (E) reactive lacquer. In a reactive lacquer for the production of coatings, basecoats, basecoats and spray bases, obtained by mixing with other additives of the binder components (A) and (B) (A) styrene 29.00 to 31.00% by weight, b) acrylic acid 1.00 to 2.00% by weight, c) hydroxyethyl methacrylate 32.00 to 14.00% by weight, d) methyl methacrylate 20.00 to 18.00% by weight, and e) based on 21.00 to 18.00% by weight of n-butyl acrylate, in which case components a), b), c), d) and e).
Are present such that these components are limited to 100% by weight, and the copolymers consisting of these components have acid numbers
Bisphenol A having 50 to 52% by weight of such a copolymer having 11 to 13 and a hydroxyl number of 120, and (B) an epoxy number of 400 to 600
And an epoxy resin based on epichlorohydrin, wherein the components (A) and (B) are present in a proportion of 100% by weight of these components, in which case they consist of (A) and (B). The binder has a solids content of 72 to 73% by weight, has a viscosity of 13000 to 15000 mPa.s at 20 ° C., a binder-solid resin acid value of 6 to 8 and a binder-solids content. Reactive lacquer for producing coatings, basecoats, basecoats and spray bases, characterized in that the hydroxyl number of the resin is from 200 to 230. 2. Reactive lacquer according to claim 1, together with up to 10% by weight of nitrocellulose used as a conventional additive. 3. A coating, a base coat, a base coat and a spray coat,
(A) and (B) hydroxyl group-containing compound, (C)
In a method obtainable by coating a lacquer based on polyisocyanate, (D) solvent and optionally (E) conventional additives on a support and curing at room temperature or elevated temperature up to 80 ° C. ) A hydroxyl group-containing copolymer, (B) an epoxy resin, (C) a polyisocyanate as a curing agent, (D) an inert organic solvent and optionally (E) a reactive lacquer with other conventional additives. (A) styrene 29.00 to 31.00% by weight, b) acrylic acid 1.00 to 2.00% by weight, c) as a solid resin in which the binder components (A) and (B) have been calculated. Hydroxyethyl methacrylate 32.00 to 14.00% by weight, d) methyl methacrylate 20.00 to 18.00% by weight and e) n-butyl acrylate 21.00 to 18.00% by weight. In this case component a), b), c), d) and e)
Are present such that these components are limited to 100% by weight, and the copolymers consisting of these components have acid numbers
50 to 52% by weight of such a copolymer having 11 to 13 and a hydroxyl number of 120 and (B) an epoxy resin based on bisphenol A and epichlorohydrin having an epoxy number of about 400 to 600, in which case the components ( A) and (B) are present with these components limited to 100% by weight, the binder consisting of (A) and (B) having a solids content of 72-73% by weight, 13,000 Using a reactive lacquer having a viscosity at 20 ° C. of ˜15000 mPa.s, a binder-solid resin acid number of 6-8 and a binder-solid resin hydroxyl number of 200-230 A method for obtaining a coating, a base coat, a base coat and a spray coat, which is characterized in that