JPS596269A - Stabilization of baking finish paint - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates to a method for stabilizing baked finishes, and more particularly to the use of light stabilizers in baked finishes, particularly automotive baked finishes.

Prior art automotive finishes are generally solutions or dispersions of organic polymers or polymer precursors in organic solvents. Most are baked finishes, which require the application of heat, generally 100° C. or higher, to cure the finish within an acceptable time after being applied to the brimer-coated metal surface. The effect of this heating is to accelerate the chemical reaction between the polymer precursors in the thermosetting system or to cause melting of the thermoplastic polymer particles.

Many automotive finishes are metallic finishes, which include flakes of metal, usually aluminum, to provide a reflective optical effect.

Such finishes are often two-layer finishes, in which a clear top coat is applied to a base coat containing pigment and metallurgy. These two-layer metallic finishes are exposed to almost twice as much radiation as normal because the polymer in the top coat is not protected by light-absorbing pigments and reflects light from the underlying metal layer. Therefore, UV stabilizers are particularly required in the top coat.

SUMMARY OF THE INVENTION It has now been discovered that certain alkyl-substituted 2,4-dihydroxybenzophenones have particularly good stabilizing properties in baked finishes.

Accordingly, the present invention provides a method for stabilizing a baked finish, which method comprises incorporating into the finish, prior to baking, an effective member of a compound of formula I below. Become.

1, in which R represents C5-12 alkyl and R1 represents hydrogen or 11-8 alkyl, preferably a branched alkyl group, such as innorogyl, sec- or tert-butyl, isoamyl or One branched chain isomer, e.g.
It is a mixture of various dodecyl isomers. More preferably R is sec-butyl.

R4 is preferably oxyhydrogen or methyl or ethyl at the 2' position, most preferably hydrogen.

The most preferred compound of formula I id: 2,4-dihydroxy-47-t-butylbenzophenone.

The compounds of formula 1 are known or can be prepared analogously to known compounds from known starting materials.

The baked finish is preferably an automotive finish, more preferably a zero metallic finish, especially a two-layer metallic finish.

Compounds of formula ■ are used in a wide range of liquid finishing coatings, such as melamine-formaldehyde resins and oil chamber polyester resins,
A crosslinking agent was added. ]? The pre-acrylate resins are suitable for use as UV stabilizers in those based on combinations with saturated polyesters or on pre-acrylate resins copolymerized with self-crosslinked polyacrylates or styrene.

Other examples are two-component topcoats based on aliphatic or aromatic diisocyanates and hydroxy-containing polyacrylates, esters or polyether resins. Thermoplastic polyacrylate resins are also useful, the latter as well as crosslinked polyacrylate resins combined with butanol-etherified melamine formaldehyde resins and hydroxy-containing polyacrylate resins cured with aliphatic diisocyanates. , is particularly effective for metallic finish paints.

The compounds of formula I may be used alone or in combination with other additives, especially other UV stabilizers. Examples include 2-(2'-hydroxyphenyl)benztriazoles, 2-hydroxybenzophenones, 2 + 2 + 6 + 6-titraargylpibasins, terrichylates, cinnamates, benzoates or substituted benzoates. , and oxalic acid anilides. Particular preference is given to using compounds of formula I together with 2.2.6.6-titramethylpiveridine.

The addition of the compound of formula I to the baked finish may be carried out at any stage of the manufacture of the finish, in solid form or in a suitable solvent such as xylene or toluene, e.g. It may be carried out in the form of a solution 71 with a concentration of .

The addition of a compound of formula I of between 0.02 and 5 weights, preferably between 2 and 2 weights, clearly improves the sunlight and climate stability of organic pigments in baked 41 paints and Reduces the tendency to form hairline cracks due to exposure and provides improved gloss retention.

Stabilization of two-layer metallic finishes is achieved by adding compounds of formula I to the base coat or clear top coat, or both. Preferably, the addition is made to the top coat only, providing excellent long-term stability against outdoor exposure and loss of gloss due to kneading. These compounds are pale
It can be used in metallic finish paints of any hue, including star colors.

The present invention also provides a stoving finish comprising a compound of formula I, either in liquid form before application or in cured form after application to a substrate. The finish is preferably a clear top coat of a baked +12 layer metallic automotive finish.

EXAMPLES The following examples serve to further illustrate the invention. In the examples, parts are given in parts by weight and temperatures are given in degrees Celsius.

Example 1 A two-layer metallic paint having the composition shown in F was prepared.

a) "15.0 parts of coating commercially available polyacrylate resin, DIN 53
Add the specified crosslinking agent to 1, 86 (Vlacryl 5C
344 + VIanova + Vlenna + supplied as a 50% solution in xylene/butanol 4:1)2
．． 61 parts of commercially available butanol-etherified melamine resin;
Moderate reactivity, prepared by condensation of 1 mol of melamine and 3-6 mol of formaldehyde 11, DIN 53187
needling with 3-6 mol of butanol (MTA
prenol MF800 + Ca5ella, supplied as a 72% solution in isobutanol) 077 parts butanol 0.26 parts colloidal silicic acid 6.70 parts xylene 51.75 parts 20% cellulose acetate butyrate with the following weight composition: Solution: 20% cellulose acetate butyrate (contains acetyl)
t 13.6%, butyryl content 3 B, 7 t, hydroxyl content 1.25%, viscosity of 20% solution in acetone = 2
00 cp10 Tibutanol 35% Xylene 35% Butyl acetate 3.85 parts non-exfoliated aluminum yeast, DIN5
13.54 parts butyl acetate 5.15 parts ethyl acetate glycol 0.37 parts Byketol OK (mixture of high-boiling aromatics, ketones and Nisdels, boiling point 16) )~185℃
, Myk-Mallnkrodt) 0.3 parts of copper phthalocyanine blue (C,1, Picment Blue 15
:1) b) ) 80.00 parts of Tubucoat d? Polyacrylate resin (same as in base coat) 13.90 parts melamine resin (same as in base coat) 4
．． 10 parts n-butanol 200 parts Byketol OK (same as in the basecoat) C) Apply the basecoat to the Glamor-coated metal plate by application spray, without UV stabilizers, in a layer approximately 251 trn thick. I got it. After drying of the base coat, coat the metal plate with 1) top coat (25 μm) of b) above without UV stabilizer or 1
1) 1 part (i.e. 1% by weight) of 2,4-dihydroxy-
The dog coat of b) above containing 4-tert-butylbenzophenone was sprayed and baked at 140° for 30 minutes.

Exposure tests (1 year in Florida, 5° south tilt) showed excellent results for metal plates coated with topcoat 1i).

F1]2 Example 1 Apply the basecoat a) and apply 2.4% of the weight over this.
The transparent topcoat of Example 1b) containing -dihydroxy/-4'-tert-butylbenzophenone was applied by spraying. The top coat thickness was 20-30 μm. The obtained finish coating is exposed to ultraviolet light equipment (UVC0N, At1
artificially irradiated in AS). . Excellent results were obtained.

Example 3 The finish obtained according to Example 2 was baked at 140° for 3 hours. UV absorption measurements from 290 to 380 nm showed that under these conditions 2,4
It was found that there was no loss of -dihydroxy-4'-t-butylbenzophenone.

patent applicant Zand Akchen Kesel Shaft patent application agent Patent attorney Akira Yoi Patent attorney Kazuyuki Nishidate Patent Attorney Yoshi 1) Keio Patent attorney Akira Yamaguchi

Claims (1)

[Scope of Claims] 1. A method for stabilizing a paint, which comprises adding an effective number of compounds represented by the following formula I into the finishing paint before the firing. 1 In the above formula, R represents C alkyl, and R1 represents 3-12 hydrogen or C1-8 alkyl. 2. The method according to item 1, wherein R is a branched alkyl group in the compound of formula I. 3. The method according to claim 2, wherein R is t-butyl. 4. The method according to any one of claims 1 to 3, wherein R1 is hydrogen or methyl or ethyl at the 2'-position f'&. 5. The method according to claim 4, wherein R1 is hydrogen. 6. The compound of formula 1 is 2,4-dihydroxy-4'-t-
The method according to claim 5, which is butylbenzophenone. 7. Claims law in which the baked finish paint is a metallic finish paint. 8. The method according to any one of Items 1 to 7 of Section 1 of Patent M, wherein the baked finish paint is a transparent top coat of a two-layer metallic finish paint. 9. When the effective amount of the compound of formula I is 0.02 to 5 ■j, M
9. The method according to any one of claims 1 to 8. 10 Baking may be carried out by incorporating into the finish paint an effective amount of a mixture of a compound of formula I as defined in claim 1 and a 2,2,6,6-tetramethyl bizelidine compound. A method for stabilizing baked finish paints. 11. Compounds of formula I according to claim 1 0.
02-5% by weight of a liquid baking finish applied to a substrate. 12. Compounds of formula I according to claim 1 0.
Baked finish paint baked on base material, including 02-5 layered joints.