US1999413A - Method of decorating surfaces - Google Patents

Description

April 30, 1935. c. B. HEMMING ET AL 1,999,413

METHOD OF DECORATING SURFACES Filed Aug. 12, 1951 METAL PIGMENTED GROUND COAT DECALCOMANIA DECORATIO CLEAK TOP COAT CLEAR TOP COAT PIGMENTED GROUND COAT DECALCOMANIA DECORATION I METAL BUT Z I NVEN TORS Charles B. Hemming far! Cfifman BY A TTOR Y.

Patented Apr. 30, 1935 -UNITED STATES I 1,999,413 METHOD OF DECORATING SURFACES Charles B. Hemming, Parlin, and Earle 0. Pitman, Princeton, N. 1., assignors to E. I. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware Application August 12, 1931, Serial No. 556,000

'7 Claims.

This invention relates to a method of decorating surfaces, and more particularly to a method employing the use of decalcomanias and to the product obtained thereby.

The present invention involves the use of the common type ofdecalcomania, in which a sheet of paper or similar material is first coated with a water soluble size, usually a gum, and then the decalcomania is lithographed on the coated surface with the back side of the decalcomania up. This type of decalcomania is'usually applied by coating the back side of the decalcomania with a water insoluble size, usually of the varnish type, and then applying the whole to the surface to be decorated when the coating has reached a tacky state. The decalcomania is then rolled under pressure and the surface subsequently washed with water to remove the paper backing and water soluble size. As a final step, the surface is coated with a clear top coat composition to protect the decalcomania.

A modification of this type of decalcomania is the so-called "duplex decalcomania, in which the decalcomania is lithographed on to thin, translucent paper in place of the usual thick white paper. As the combination is rather fragile, the whole is mounted on thicker paper by means of a very light coat of a gummy adhesive. This type of decalcomania is used in the same manner as the first type, except that after the decalcomania is applied to the surface to be decorated the thick sheet of 'paper is stripped off without washing, the second thin sheet being removed by washing as in the ordinary decalcomania. This type of decalcomania is advantageous due to the fact that the thick sheet may be waterproof, obviously impossible in the ordinary decalcomania, and also the thin sheet may be readily removed by washing, .thus reducing the danger of damaging the design layers of delicate decalcomanias.

There are other types of decalcomanias employing the same basic principles, among which may be mentioned the recently developed thin photo film decalcomania.

All of these decalcomanias are far from satisfactory, the basic difllculty usually being due to the fact that the design layer of thedecalcomania itself is not anchored securely to the surface to be coated and, as a result, the detail of the design layer is likely to be blurred while being applied, and lifting and poor wearing qual-' ities frequently are characteristic of surfaces decorated injthis manner.

An object} of the present invention is to provide a method whereby the decalcomania is firmly anchored to the surface to be decorated so that the above difficulties are avoided. Other advantages will be apparent from the description Hi-fiash naphtha The above objects are accomplished according to the present invention by first applying to the surface to be decorated a ground coat adapted to 'harden on application of heat, then allowing this ground coat to dry until it reaches a tacky state, then applying the decalcomania, using pressure and a somewhat elevated temperature. Preferably, the decalcomania is applied by means of a hydraulic press. After application of the decalcomania the surface is washed to remove the paper or similar backing of the decalcomania and the water soluble size, and the coated surface is then baked until hard. Subsequently, a clear top coat is applied to the decorated surface and this is preferably also a composition adapted to harden upon the application of heat. If this type of clear top coat is employed, the surface is again baked to harden the top coat.

One embodiment of the invention is illustrated in the accompanying drawing in which Fig. 1 shows a sectional view and Fig. 2 an elevation, with parts broken away for clarity, of a metal sheet decorated as described in the example below.

The following example is given to illustrate a preferred method of carrying out the present invention:

Example 1.A pigmented ground coat was applied by roller coating, directly to a clean metal surface which had been scuffed, and air dried for approximately 1 hour, at the end of which time the coat was slightly tacky. The composition of this ground coat was as follows:

. Per cent Titanium oxide 34.0 Modified polyhydrlc alcohol-polybasic acid type res n I Petroleum solventnaphtha Heavy petroleum naphtha Mineral spi Modified p lyhydric alcohol-polybasic acid type resin.

Per cent Phthalic anhydride 46.30

Glycerol 21.24

Linseed oil acids 30.97

Gly l 1.49

After the specified drying period the decalcomania was applied by laying it on the slightly tacky ground coat, placing the whole on a hydraulic press and applying a pressure of 900 pounds per square inch.

of the invention given hereinafter. the plates of the press 50' Per cent Polyhydric alcohol-p'olybasic acid type resin (described above) 30.0 Blown rapeseed oil 1.0 Hi-fiash naphtha 64.4 5% cobalt linoleate solution in turpentine- 4.4 Oil of cloves 0.2

The above example gives a very specific method of carrying out the present invention and may be modified greatly. It has been found that the following represent approximately the operative limits of the process:-

Decalcomania, anchoring pressure 40# to 900# per sq. in. Decalcomania anchoring temperature C. to C. Decalcomania anchoring time .05 to 5.0 minutes Ground coat and final baking temperature 60 C. to 150 C. Ground coat and final 1 baking times 8 hours to 20 minutes It will be understood, however, that the invention can be carried out, and may be carried out, outside of these limits under special, circumstances. As will be apparent to those skilled in the art, the baking period will vary inversely with nespect to the baking temperatures given above.

It is preferred to apply the ground coat and the clear top coat by roller coating, although same may be applied by dipping, brushing, spraying, or other methods used in the art.

The method of decorating is obviously not only applicable to metal, but to many other surfaces, such as wallboard, linoleum, and similar compositions of matter.

The type of ground coat composition used'in this method is of great importance and must be such that it gives a film that will harden upon application of heat. By this is meant that the ground coat composition must be such that the application of heat will cause oxidation, polymerization, condensation or similar change to give both a hard and inert film, as contrasted with compositions that merely dry through evaporation of solvents, such as nitrocellulose lacquers. Synthetic resin compositions are particularly suitable for the ground coat composition, for example, polyhydric alcohol-polybasic acid glyptal type resin compositions and compositions employing phenol-formaldehyde resins, urea-formaldehyde resins, and the like. The oil type varnishes are also suitable for this purpose, although not as preferable where a metallic surface is to be decorated, as usually a primer coat must first be applied to the metal to secure adequate adhesion of the oil varnish. With the synthetic resin compositions excellent adhesion is obtained without the use of a primer coat. As

will be apparent to those skilled in the art, the

particular formula to be used can be widely varied. Various diluents, softeners, solvents, and pigments, and combinations thereof may be em ployed, the main consideration being that a composition of the hardening type disclosed is used.

The following formula is given to illustrate a typical 011 type varnish suitable for use as the ground coat according to the present invention. The particular formula is well adapted for a ground coat where a walnut grain effect is desired on a surface:

The pigments for this formula consist of Ferrite yellow dark orange Lithopone Chrome yellow medium Whit n Cosmic black Red oxide In the manufacture of this finish, the pigments are ground in the varnish base. The other ingredients specified above are added in the final mixing cycle.

The composition can be widely varied, as will be understood by those skilled in the art. The varnish may comprise a combination of China-wood oil and linseed oil, with or without resins, and with a wide variety of solvents, diluents, drlers, and pigments. v

Regardless of whether a synthetic resin type ground coat or an oil varnish ground coat is used, the ground coat is allowed to dry until substantially all of the volatile solvents therein have evaporated before applying the decalcomania. In either type of ground coat a tacky film will be left after the volatile solvents have evaporated.

The composition of the clear top coat may be varied even more widely than the ground coat. Any composition that will give a clear film of setisfactory durability may be employed, although it is preferred to use a synthetic resin composition that will harden on heating so that by a final bake a product of great durability is obtained. However, cellulose derivative coating compositions and other coating compositions which dry simply through evaporation of the solvent constituent may be employed. Since the ground coat will have already been baked and thereby hardened prior to application of the clear top coat and become substantially insoluble in coating composition solvents, any known solvent mixture may be used in the top coat without danger of lifting or other harmful effects that would result if the ground coat were subject to attack by the solvents in the clear coat. If desired, the clear top coat may be omitted, although it is preferred to have a protective coat over the decalcomariia.

It is believed that the greatly improved anchorage of the design layer of the decalcomania according to the present invention is due to the use of a ground coat composition adapted to harden on application of heat, and the application of the decalcomania with heat and pressure to the coated surface. The decalcomania is forced down into the ground coat, which affords a good-anchorage while the backing of the decalcomania is removed by washing and the subsequent baking and hardening of the ground coat effects a lasting anchorage of unexpected strength.

The particular construction of the decalcomania forms no part of the present invention,

except that it is necessary to have the decalco- -mania manufactured with its front side in contact with the sheet of paper, or other backing used. The term decalcomania is used throughout to include only this-type of decalcomania. The term design layer employed in the claims is used to define the decorative layer which, together with the paper backing and sizing, forms the decalcomania. Where a duplex decalcomania of this type is used, obviously the thick sheet of paper backing must be stripped off dry before the washing step.

The decalcomania can be applied to the tacky ground coat in a varietyof ways, such as by roller, hydraulic press, etc., as long as some pressure is applied in forcing it down. It is preferred to place the article to be decorated between the plates of a hydraulic press and then to apply the decalcomania with heat and pressure within the limits above specified. By this means-delicate decalcomanias can be applied without the slightest blur or imperfection.

The method of the present invention may be successfully utilized in the manufacture of metal furniture, automobile dashboards and moldings, in tin decorating, in the production of wall tile involving decalcomania transfers, linoleum desk tops, et cetera.

An important advantage of the present method over methods heretofore known for applying decalcomanias, is the greatly improved anchorage of the decalcomania to the surface to be decorated. Lifting, which heretofore had generally been encountered in surfaces decorated with decalcomanias is entirely eliminated. Furthermore, decalcomanias applied according to the present invention are so firmly anchored that they are able to withstand severe forming operations upon the decorated surface without peeling or cracking at the points under stress. This latter characteristic is'of great advantage in manufacturing dash boards and other metal articles which must be subjected to a forming operation.

The present method is extremely simple and easily carried out in commercial production. Surfaces such as clean scuffed auto body steel, or

ed surface until taclw, applying a decaicomania upon application of heat", as used in the ap- 5 pended claims, is meant a composition that will harden and become substantially inert upon application of heat, to various coating composition solvents.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. Method of decorating a surface comprising applying a ground coat composition thereto adapted to harden upon application of heat, drying the coated surfaceuntil tacky, applying a decalcomania to the coated surface at a temperature of IO- C. and, pressure of 40-900 pounds per square inch,'washing the surface to remove the backing and sizing of the decalcomania, baking the coated surface until hard, and applying over the coated surface a clear top coat.

2. Method of decorating a surface comprising applying a polyhydric alcohol-polybasic acid resin ground coat composition thereto adapted to harden upon application of heat, drying the coated surface until tacky, applying a decalcomania to the coated surface with pressure, washing the surface to remove the backing and sizing of the decalcomania, and baking the coated surface until hard.

3. Method of decorating a surface comprising applying a polyhydric alcohol-polybasic acid resin ground coat composition thereto adapted to harden upon application of heat, drying the coatto the coated surface with heat and pressure, washing the surface to remove the backing and sizing of the decalcomania, baking the coated surface until hard, and applying over the coated surface a clear top coat.

4. Method of decorating a surface comprising applying a polyhydric alcohol-polybasic acid resin ground coat composition thereto adapted to harden upon application of heat, drying the coated surface until tacky, applying a decalcomania to the coated surface with heat and pressure, washing the surface to remove the backing and sizing of the decalcomania, baking the coated surface until hard, applying over the coated surface a polyhydric alcohol-polybasic acid resin clear top coat adapted to'harden-upon application of heat, and again baking the coated surface to harden the top coat.

5. Method of decorating a surface comprising applying a polyhydric alcohol-polybasic acid resin ground coat composition thereto. adapted to harden upon application of heat, drying the coated surface until tacky, applying a decalc'omania to the coated surface at a temperature of 70-150 C. and with a pressure of 40-900 pounds per square inch, washing the surface to remove the backing and sizing of the decalcomania, baking the coated surface until hard, app yi over the coated surface a polyhydric alcohol-polybasic acid resin clear top coat adapted to harden upon application of heat, and again baking the coated surface to harden the top coat.

6. An article comprisingabasehavingahard 75 baked ground coat comprising a polyhydric alcohydric alcohol-polybasic acid resin, a design layer hol-poiybasic acid resin, a design layer over said over said ground coat, and a hard, baked, clear ground coat, and a hard, baked, clear top coat top coat comprising a polyhydric alcohol-polycomprising a polyhydric alcohol-polybasic acid basic acid resin applied over said design layer. 5 resin applied over said design layer. 6

'7. An article comprising a sheet; of metal hav- C RLES B. HEMMING. ing a hard baked ground coat comprising a poly- EARLE C. PITMAN.

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