US1994697A - Process of preparing polished top surfaces on wood - Google Patents

Description

Patented Mar. 19, 1935 PROCESS OF PREPARING POLISHED TOP SURFACES ON WOOD' 7 Arthur Eichengriin, Charlottenbnrg, Germany, assignor to Ceianese Corporation of-Amerlea, a corporation of Delaware 7 No Drawing. Application October 19, 1931, Serial No. 580,848. In Germany October 20, 1930 16 Claims.

This invention relates to the imparting of polished surfaces to wood and like material, and relates more particularly to the use of thin foils of plastic material as coatings for such surfaces.

6 An object of my invention is to impart beauticellulose acetate.

ful polished. surfaces onto wood or analogous material in a cheap and expeditious manner. Other objects of this invention will appear from the following detailed description.

It is well known that the polishing of smooth wooden surfaces requires a very considerable expenditure. of manual labor and therefore polished wood is very expensive, even if there is used for this purpose the recently developed method of spraying of lacquer on wood. Furthermore, wood which is coated with a spraying lacquer containing a cellulose derivative must be polished by hand or mechanical devices in order to obtain a high gloss.

For this reason many attempts have already been made to provide wooden surfaces with a smooth and glossy surface by laminating onto the same thin sheets of a plastic materiahas for example plastics containing cellulose nitrate or These. laminations were carried out in the same manner as the application of thin veneer to wood surfaces, namely by causing the sticking with, the aid of a suitable glue or an adhesive solution or adhesive paste, which for example contained resins, cellulose esters and such solvents as were capable of softening the layers of the plastic material and therebycausing adhesion of the same. v

However the prior methods have found but slight commercial application, on account of the fact that the more or less thick sheets of celluloid or analogous plastic materials separated in time from the wood under-surface, especially at the sectional planes or edges and also blow-holes formed easily in the flat surfaces through insumcient adhesion, due to the difference between the behavior of the plastic material as against the wood towards atmospheric moisture, temperature and mechanical requirements.

I have now made the surprising discovery that these drawbacks can be completelyv avoided, if the adhesion between the plastic foil and the wooden surface is obtained, not with theJaid of an intermediate layer, but through the simultane ous application of heat and pressure. To be sure this process can be carried out only with foils of rather little thickness, which makes it possible to press the foils as deepas possible into the pores of the wood, so that they become anchored-therein,a result that is not possible with thick sheets, for example suchas those having a thickness of 0.5 mm. or over, since the latter do not yield sufficiently, and upon the cooling of the wood surface separate in whole or in part. This is not the case if there are used thin foils of plastic-material, as for example such as are made from. cellulose derivatives alone or preferably in admixture with a plasticizer or softening agent, or such other layer-forming material which become plastic when warmed, such as foils havin a thickness of only 0.07 or 0.1 to 0.2 mm. and preferably a thickness of only 0.02 to 0.05 mm. Such very thin foils can be united very easily by heat and pressure to the wood surfaces and ad-. here to the same for a long time without being affected by moisture and temperature conditions. This adhesion is so firm that the foils can be used in place of 'lacquering or rather polishing, especially if the pressure is applied by means of glossy or highly polished surfaces of glass, stone, metal, etc., whereby simultaneously with the fixing of the foil upon the wood, there is produced a high polish that far surpasses the usual han'd polishing.

The pressure may be applied by means of polished metal plates, which are preferably heated to a temperature of 80 to 125 C., or by means of metallic or stone rollsor by means of thin metal sheets made of steel, aluminum, brass, etc. which are pressed against the foils by mechanical devices, which metal sheets or foils may be em ployed as an intermediate layer between the foil and the press plate or press roll which may bemade of raw unpolished metal, or the pressure may be applied by means of smooth non-adhering surfaces made of other materials. a

The ease with which the thin foils can be forced into the pores of the wood at temperatures below that at which they melt and atwhicli they do not even in a measure become plastic, provided the pressure is sufficient, is surprising, since at lower pressures even with higher temperatures, adhesion cannot be attained. The pressed foils, since they are pressed into the very pores'of the wood,

present in general the structure of the latter.

However if a suitable filler or a primer coating preparation containing resins, drying oils, albuminous materials and the like is first applied to the wood, whereby the surface of the wood is rendered smoother, there are obtained completely v smooth, highly polished surfaces. Naturally it is possible to obtain a matt or other ornamental surface. instead of a. polished surface, if the foil is pressed against plates or rolls providedwith e veneers of fine wood.

a polished surface.

This new process is particularly remarkable, since it was not heretofore possible to stick foils on wood with the aid of an adhesive or cement, since either the foils became so greatly soaked with the adhesive that the upper surface presented no polished characteristics, or the adhesive power of the adhesive was lost to such an extentv upon complete drying, that the foils peeled ofi again, or these methods produced useless results because the adhesive'could be seen through the transparent foils and spots developed.

Contrary to this, the present process can not only be carried out without defects, but produces This process, for this reason, is particularly suitable for the preparation of fine veneers from cheap varieties of wood and for the increasing of. the beauty of laminated wood, which are particularly suitable for this manufacture, since they themselves are prepared by the pressing together of individual veneers. For this purpose colorless or only slightly colored foils are. preferably employed. Since it is merely necessary to employ a foil of plastic material for the preparation of a high polish on the outer layer of the laminated wood, and if necessary on both of the outer layers of the laminated wood, a highly polished laininated wood can be prepared, if desired, in a single operation from individual veneers, adhesive lay-.

ers and foils.

The foils employed may be transparent, either colorless or colored, or they may be opaque, that is mixed with filling material and pigments or black. In case no large surfaces are to be polished, but rather preformed objects of wood, frames, furniture parts or other articles of use, the above process can be carried out with the aid of hollow bodies or molds having polished interiors.

It is also possible to apply to the wood surfaces the layers of plastic material, not in the form of isolated foils, but the foils may be produced on suitable bases, for instance upon polished tin plates, and these, while still on the plates, may be pressed with heat and pressure upon the wood surface, whereupon after cooling the thin metal plates can be separated frbm the foil coating which now sticks firmly to the wood.

In other mode of carrying out this invention, the thin foils may be produced upon. the wood surface itself, for example by spraying a solution of cellulose acetate orother derivative of cellulose and a softening agent or plasticizer in an organic solvent,- drying the layer (which in this state can be detached from the wood) and pressing the same against heated polished metal plates or.metal rolls under pressure. Also other methods of application of 'the foils may be used for this purpose. 3

. 1,994,697 corresponding etched or like surface, instead of in the simuitaneous application of heat and high pressure, whereby the. temperature is preferably so chosen that the layers are converted into a plastic condition, but are not brought to the softening or to the melting point, in order to avoid its absorption into the. wood.

The use of thin 1011s presents a considerable difi'erence over the use of film-like or sheet-like layers of normal thickness, since the thicker sheets do not adhere to smooth planed wood even when they are pressed on such wood by the above described process. whilst thin foils cannot be separated, when applied by this process, even from planed wood.

invention may be made of any suitable thermoplastic material, and may contain derivatives of cellulose such as cellulose acetate, cellulose formate, ethyl cellulose, benzyl cellulose, or other plastic materials, such as polyvinyl resins and the like.

In order further to illustrate. my invention, but

The thin foils employed in accordance with my without being limited thereto, the following specific example is given.

Example A foil, prepared from 10 parts by weight of cellulose acetate and 2 parts by weight of triphenyl phosphate, which becomes soft at. about C. and melts at C. is loosely placedupon a sheet of birch wood. A polished brass sheet is placed on top and pressure of 40 atmospheres is applied in a hydraulic press, which is heated to a temperature of 80f C. After about 15 minutes, the press is cooled by water, and after removal of the pressure,the sheet is removed. The brass plate can easily be removed from the foil, which by this time is firmly united to the wood and which forms on the wood a polished coating, which brings out the structure of the woodiin an extraordinarily beautiful manner.

Special colored eifects can be imparted to the wood or analogous material, such as paste board, leather board, fibre board, etc., either by coloring the same, or by the application thereto of grainings, colored figures, prints, mottled ornamentations of all kinds, pressed plants, stencil cut-outs before the foil is pressed thereon.

In this manner such a colored ground may be provided with a glass-like protective coating,- 9. result which was heretofore extraordinarily difficult to obtain, since similar results could be obtained only with the aid of lacquers or adhesives containing solvents which in most cases dissolved the dyestuffs iniwhole or in part. For this reason the preparation of ordinary shellac polishes on surfaces of wood or paste board having colored figures was possible only in few cases, since most of the colors would bleed owing to the action of the solvent of the polishing coat.

p Since thin foils, especially those made of cellulose esters, can be easily united by heat and pressl'ire, it is possible to place several thin foils on top of each other, whereby not only can a polishing coat of desired thickness be produced but also coatings of various hardness.

For instance a foil consisting of pure cellulose acetate without plasticizer, which can be caused to adhere only under very high pressure, can t be united to a surface of wood or fibre board. by first pressing onto the surface a soft and therefore easily adhering foil, which consists of cellulose acetate and plasticizer'or camphor substitutes, or resins, artificial resins, oils, etc., and thenuniting thereon the hard foil with the use of low temperatures and low pressures. Or else two or more foils can be loosely placed upon each other and pressed in one operation, whereby vatemperatures and high pressures.

rious foils, not only having different degrees of hardness, but also if desired having different. ,colors, color effects, designs, and figures can be employed. These various foils can also be made of, diiferent materials such-as cellulose nitrate,

cellulose acetate, cellulose ethers,-' vinyl'resins and the like, provided that they unite together on application of heat and pressure.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention. 1

Having described my invention what I'claim and desire to secure by Letters Patent is: 1. Process of imparting polished surfaces to wood, which comprises applying directly to the wood surfaces preformed thin foils of a thermoplastic material having a; thickness of'0.02 to 0.2 mm. and pressing by means of a polished surface at elevated temperatures and high pressures.

2. Process of imparting polished surfaces towood, which comprises applying directly to the wood'surfaces preformed thin foils of a thermoplastic material containing cellulose acetate and having a thickness of 0.02 to 0.2 mm. and pressing by meansof a polished surface at ele-- vated temperatures and high pressures.

3. Process of imparting decorative surfaces to wood or like material which comprises applying to said material a plurality of preformed thermoplastic foils of different constitution, and

pressing at elevated temperatures andhigh pres sures. v 4. Process of imparting decorative surfaces to wood or like material which comprises applying to said material a plurality of preformed ther-' moplastic foils of different chemical-constitution, and pressing at elevated temperatures and high pressures.

5. Process of imparting decorative surfaces to Wood or like material which comprises applying to said material a plurality of preformed thermoplastic foils of differentchemical constitution, at least one of said foils containinga derivative of cellulose, and pressing at elevated temperatures and high pressures.

6. Process of imparting decorative surfaces to wood -or like material which comprises applying to said material a'plurality of preformed thermoplastic foils of different degrees of hardness, and pressing with a polished surface at elevate '7. Process of imparting decorative surfaces to wood or like material which comprises applying to said material a plurality of'preformed thermoplastic foils containing different proportions 3 of plasticizer, and pressing with a polished surface at elevated temperatures and high pressures.

8. A laminar product presenting a highly polished surface comprising a base of wood and a.

layer of preformed thermoplastic foil having a thickness of 0.02 to 0.2 mm. adhering directly to the surface of said wood.

9. A laminar product presenting. a highly polished surface comprising a base of wood and a' ished surface comprising'a baseof wood-like material, a layer of thermoplastic foil adhering directly to the surface of said wood-like material and a thermoplastic foil of different chemical constitution superposed on the first layer of foil.

12; A laminar product presenting a highly pol-.

material, a layer of thermoplastic foil adhering directly to the surface of said wood-like material and a thermoplastic foil, of difierent-chemical constitution superposed on .-the first layer offoil, at leastone of said foils containing a derivative of cellulose. U

13. A laminar productpresenting a highly polished surface comprising a base of wood-like .material, a layer of thermoplastic foil adhering directly to the surface of .said wood-like material and a thermoplastic foil having a different degree of hardness superposed on the first layer of foil.

14. A laminar product presenting a highly polished surface comprising a base of wood-like ma.- terial,.a layer of .thermoplasticfoil adhering directly to the surface of said woodelike material ,ished surface comprising a base of wood-like' and a. thermoplastic foil containing a. different proportion of plasticizer superposed on thefirst layer of foil. 4

15. Process of imparting polished surfaces to wood, which comprises applying directly. to the wood surfaces preformed thin foils of a thermoplastic material and pressing by means of a polished surface at elevated temperatures and high pressures.

16. A process for producing decorative coatings or surfaces, which comprises applying'to the surface to be coated a dry solid film of a thermoplastic cellulose derivative and pressing said film onto said surface inthe absence of a solvent by means of a polished plateat elevated tempera.- tures and high pressures.

.ARTHUR EICHENGR'UN.