US2078291A - Composite novelty finish - Google Patents

Description

Patented Apr. 27, 1937 UNITED STATES COMPOSITE NOVELTY FINISH Carl B. Smedley, Bay Village, Ohio, asslgnor to The Glidden Company, Cleveland, Ohio, a corporation of Ohio No Drawing. Application February 14, 1934, Serial No. 711,272

Claims.

This invention relates to novelty finishes, and particularly to composite finishes. comprising a baking undercoater and a decorative partial top coat of the type known variously as spatter, veil- 5 ing, spider-web, hammered-effect, etc.

Thebuilding up of such finishes is well known in the art. The practice is to prepare a base material, using any available material-lacquer enamel, oil varnish enamel and alkyd or phenolaldehyde resin enamels, either air drying or baking the film to resist the action of the solvents in the top coat. The top coat is then sprayed; the precise type will depend on the efiect desired, but all of these materials will spray out of a gun in strings or chunks, instead of a smooth spray; they hit the surface relatively dry, and stay in place nicely, to give the various effects.

Finishes prepared in this manner are essentially base coats, with partial top coats thereon, held by the mutual adhesion between the top-coat and the base coat. They are, of course, rough, owing to the fact that the top coat lies on top of the base surface, and covers only part of the surface.

This gives rise to two distinct disadvantages of 25 these composite finishes-a tendency to pick up dirt, owing to the roughness of the surface, and a tendency for the top-coat to separate from the undercoater. This latter tendency may become very pronounced, as the very materials which give 0 the desired string to the finishes reduce their adhesion.

Of course, where a lacquer top coat is used over a lacquer undercoater, the bond is a trifle better than where a relatively insoluble undercoater is used; the adhesion, however, still leaves something to be desired, because little of the lacquer solvent in the top coat strikes the work, the stringy material being reasonably dry.

I have found that both these objections may be 40 overcome, using the same materials as heretofore, by applying the top-coat to the partially dried unolercoater, and drying the two materials together. I have further found that it is necessary to bake the two materials together in order to get the best 45 effects.

The unclercoater may be any of a large variety of the common enamels. Lacquer enamels however, generally set up too rapidly to give the desired effect of coalescence of thetwo coats; many 50 paint enamels take too long to set up to make their use practical in production shops. The undercoater should be allowed to lose part of its solvent; it should be set to the stage where it is still tacky to the fingers, allowing a finger print to register easily, but should not be so wet that the print flows out readily. The top coat is then sprayed as desired. In this manner, the top coat forces itself into the undercoater, embedding itself to such an extent that adhesion is assured, and roughness is reduced; but the condition of the undercoat is such that it will not flow over and entirely hide the strings and blotches of top-coat.

With air-drying undercoaters other than nitrocellulose lacquer, the proper dry point is difllcult to determine; and, what is more important, the long time required for the air drying materials to lose all flowing tendencies generally results in substantial submersion of the strings of the top coat. Nitrocellulose lacquers may be formulated to stay open long enough to meet the desired conditions; but solvents for the purpose are expensive and the wet lacquer tends to dull the edges of the top coat, by dissolving it. In addition lacquer ordinarily gives a relatively poor priming film on metal; and costs generally prohibit a two-coat undercoater on this sort of finish. a result of these difiiculties, I prefer to use a baking undercoater.

I find that alkyd resin enamels are particularly easy to control as to the proper setting time, due to the common use of fast coal tar solvents in formulation; varnish-type enamels should be preferably formulated with relatively fast evaporating naphthas. A typical ready-to-spray alkyd base coat may be made as follows:

50% solution of a 37% linseed oil 63% glycerol phthalate resin in toluol and Chrome green paste lpd.

(These two pastes consist of 8# of pigment per gallon of above resin ground on stone mill.)

A satisfactory oil base material may be made as follows:

Ultramarine blue in grinding varnish- 1 pds. Titanium dioxide in grinding varnish (semi-paste) pt. 15 gallon ester gum-wood oil varnish- (45% solvent-mixture of solvent naphtha and mineral spirits) 4 pts. Ester gum solution (65% in mineral spirits) 1 pt. Naphtha (low boiling) V2 pt.

Xylol 5% pt.

This reduces about 4 parts enamel to 1 of naphtha for spraying or dipping.

While these formulas are representative of materials successfully used as undercoaters, others have been used'to give good results; the essential feature is the fairly rapid set-up to the stage where the top coat will adhere well without sinking away. Both of the above products will set up in from 2-5 minutes, to take the top coat. Other similar products may easily be formulated.

The top coats vary, depending on the effect desired, being alike only in the fact that they spray in strings or blotches, and do not flow. The chosen type is sprayed; when the decoration is complete, the top coat is embedded in the partially wet undercoat; the system is then baked, the bake time and temperature varying with the undercoat. The undercoats given in the examples both bake hard in 60 minutes at 200 F., or 45 minutes at 225 F. In general, baking temperatures may vary from F., to 300 F.; the higher temperatures should be avoided where the decorative coat contains nitrocellulose.

As examples of top coats, I may prepare a lacquer as follows:

Ounces Base solution (made by dissolving 1 pound of Goodyear Pliolite rubber resin in 24 ounces of toluol) 32 Butyl acetate 4 Toluol 4 Alkyd resin-titanium oxide paste (as above) 1 Alkyd resin-chrome green paste (as above)- 4 This material sprays full body, gives very fine strings with practically no blotches.

A full body spraying lacquer which gives coarser strings with a fair number of small blotches may be made as follows:

A rubber solution is made by dissolving 4 ounces of crepe rubber in 1 gallon of toluol. A nitrocellulose base solution is made from Ounces 1000 R S nitrocellulose (wet with 30% alcohol) 20 Ethyl acetate 62 Butyl acetate 31 Denatured alcohol 62 Benzol 94 A clear lacquer is then prepared as follows:

Ounces Rubber solution ,10 Nitrocellulose solution 17 Mixed solvent (as above) 13 The lacquer is pigmented as desired with regular lacquer pigment bases, ground on a stone mill with castor oil and ester gum solution. A typical color would be made as follows:

Ounces Clear lacquer 48 Titanium dioxide paste 4 Prussian blue paste 2 By increasing the amount of solid content in the lacquer in relation to the rubber, the strings become heavier, and the blotches larger. With 7 parts of a bronzing lacquer (containing 9% of 4 second nitrocellulose (dry) 9% of ester gum and 3% of castor oil) to 1 part of the rubber solution, the strings disappear, and a blotchy effect is obtained. When pigmented with metallic powders, and used over a metallic base, the efiect of hammered metal may be obtained.

Stringy and blotchy effects can be obtained not only with rubber and rubber resins, but with other high molecular Weight resins. The vinyl resins, with proper solvents, make stringy coatings which are known to the art; and styrol resins can be used in similar fashion.

I do not limit myself in the top coats used, except that they are of this high molecular weight type, which spray dry, and have relatively little flow after striking the panel. The base coats are also possible of variation, my invention being directed to the combination of the two coats so as to get good adhesion, and a relatively smooth film as compared with those of the prior art, without getting complete submergence of the decorative top-coat in the undercoat.

Having described my invention, I claim:

1. An article coated with a decorative finish comprising a base coat, and a top coat comprising strings and/or blotches of a coating, of the class consisting of rubber and synthetic high molecular weight resins, imbedded in said base coat but not entirely covered thereby.

2. The article of claim 1, in which the base coat comprises alkyd resin.

3. The method of preparing a composite finish which comprises coating a surface with a base coat, allowing it to set, spraying thereon a coating, of the class consisting of rubber and synthetic high molecular weight resins which forces strings and/or blotches of material into the base coat, and drying the composite coating.

4. The method of preparing a composite finish which comprises coating a surface with a base coat, allowing it to set to a point where impressions are easily made, but are not flowed out, spraying thereon a coating, of the class consisting of rubber and synthetic high molecular weight resins which forces strings and/or blotches of material into the base coat, and drying the composite coating.

5. The method of preparing a composite finish which comprises coating a surface with a base coat, allowing it to set to a point where impressions are easily made, but are not flowed out, spraying thereon a coating containing rubber which forces strings and/or blotches of material into the base coat, and drying the composite coating.

CARL R. SMEDLEY.