US1875054A - Composite material and process of making the same - Google Patents

Description

Patented Aug. 30, 1932 PATENT OFFICE EMIL C. LOETSCHEB, F DUBUQUE, IOWA.

Np Drawing. Application filed Apr-i117,

hardness, smoothness and finish obtainable in hardwoods only by painstaking and tedious hand labor.

Inasmuch as the process is applicable. for the. production of various articles in which fibrous or cellulosematerials are substituted for natural woods, the following description will be confined to the method of making a door panel as illustrative of the general procedure followed.

The base material for the panel or other piece to be made, may be any one'of a number of prepared fibre or pulp boards used for insulation and'wall construction, and consisting of a mass offibres compressed into a solid sheet and having the characteristic fibrous surface texture. Having prepared a piece of the base material of proper size and thickness for a panel, the first step in its treatment s to spray on or otherwise apply to the surface. a solution of a phenol-condensation product. such as Bakelite and alcohol, although certain natural gums may be used in place of Bakelite. such as shellac, kauri or Congo gum. Bakelite is preferred as it produces a superior finish but is more costly, and therefore a cheaper substitute will often suffice, or in some cases. the Bakelite is replaced in part by one of the cheaper natural gums,- the proportion of Bakelite, however, deter- .mining the quality of the ultimate surface finish.

After the treament with the Bakelite solution and while the surfaces to be finished are still partially wet and in tacky condition, a coating of pulverized or finely dividedfibrous or cellulose substance. such as wood flour or ground eornstalk pulp, is sifted over the surfaces to form a coating of substantial thickness. This dry coating is then pressed into the varnish-like surface by means of roll- COMPOSITE MATERIAL AND PROCESS OF MAKING THE SAME 1929. Serial No. 355,992.

ers passed over the surface, or by passing the coated panel between power driven rollers, whereupon it is then subjected to a drying process in a suitable dry room or enclosure whereby the solvent remaining in the Bakelite solution is driven off, leaving the'surface coating practically dry.

As a practical and satisfactory variation in the process, any suitable fibrous material 1n sheet or woven form, such as heavy paper, cardboard, or cloth, may be used in place of the pulverized substances before-mentioned. In this case, I prefer to use a thin solution of Congo gum spirit varnish dis solved in a suitable solvent, with or without the addition of varying percentages of Bakelite varnish as the primary coating for the panel surfaces. I find that Congo gum is Very satisfactory as an adhesive. in addition to having a high melting point, and combines readily with Bakelite, the latter being advantageous due to its hardening qualities.

In some respects the use of paper and the like is advantageous, in that it provides a veneer over the base material and as such materially increases the strength.

Continuing with the next step in the process. the dried panel is now subjected to a combined heat and pressure treatment, a press of the hydraulic type. being preferably used for this purpose. Moreover, especially prepared platens or plates are provided, the same being hollow and provided with corn nections for the circulation of steam and cooling water theretlnmigh for heating and cooling the platens. Depending on the degree of compactness desired in the finished panel, the pressure exerted may varyfrom 100 to 1000 pounds per square inch. it being evident that the greater the pressure the greater will be the strength of the panel. The pre sure is applied for a period of from five to ten minutes, during which time the platens are heated, whereupon they are allowed to cool, down to the normal temperature or be artificially cooled in the manner already suggested. 5y reason of the application of heat. the resinous substance or Bakelite, or a mixture of the two as the case may be, become hardened or set, and with the accompanying pressure and cooling, a hard and smooth surface finish is produced, showing none of the characteristic fibrous texture of the raw base material.

Upon removing the panel from the press, it is ready for the final surface finish. I or ordinary surface decrn'ation, paint, enamel,

lacquer orvarnish may be applied to the panel in the same manner as they would'be applied to a wood panel, although fewer coats are required due to the smooth and uniform character of the surface. If desired. the surface may be grained in imitation of natural wood by any suitable graining or grain reproducing process, and a final protective coat of varnish applied. or if a more finished surface is desired. severalcoats ofnatural resin varnish or lacquer may be applied in the usual manner and rubbed down, as in the case of natural wood finishes.

v However. to produce what may be regarded as a fine finish, the panel n'iaytbe. further theated as follmvs:.-\ssuming that the panel has been removed from the press after the combined heat and pressure treatment. a

fairly heavy solution of Bakelite varnish is applied overthesurface, and the panel again placed in the drying room for the purpose of expelling the solvent in the Bakelite varnish solution. At first, the drying is allowed to continue slowly at a relatively low temperature, whichis graduallv increased to from 240 to280 R, at which temperatures the In this manner, the Bakelite coating is subjected to a temperature of say 250 F. to

, 275 F. for a period sufficient to cure the Bakelite. Ordinarily, one-half hour atthe temperature stated is adequate, although the nary acids and solvents, or exposure to temperatures as high as 400 F. a I

As will be seen from the foregoing, the process may be carried only to the pointof producing finishes suitable for ordinary interior work, or may continue to the point of providing an exceedingly: hard and lasting surface. having all of. the lustre and beauty obtainable in natural woods, but of greater desirability and at a greatly reduced cost, both as to the raw materials and the labor involved.

Havingsct forth a preferred embodiment of my invention, I claim as new and novel:

1. A process for producing-a composite material consisting of coating a sheet of base material composed of a partially compressed 1 mass of cellulosic fiber pulp with a resinous varnish and. drying the same to provide ..a tacky surface, applyinga thin layer of pulverized fibrous material over'said surface, subjecting said basesheet to heat and pressure,

applying a solution of a phenol-condensate product over'the surface of the treated sheet and again subjecting the same to heat sufiipient to render said product hard and infusible.

2. A process for producing a co mp osite.

material consisting of coating a sheet, of fibrous material derived from corn-stalk or wood pulp with a resinous varnish, applying a thin layer of fibrous material over said f coated surface. sub ectmg said base sheet to p, 1

heat and pressure treatment, applying a phenol-condensate product over the surface of the treated sheet and again subjecting the same to heat sufficient to rendersaid product hard and infu sible.

EMIL. C. LO ETSCHER.

time may be shortened by increasing the temperature.

During the heating processin the press, the Bakelite first becomes fusible and spreads over the surface of the panel in a smooth, even film, and later becomes infusible. WVhen this condition is reached. the platens are then cooled by water, and the panel removedfrom the press.

This final-treatment with Bakelite varnish produces an exceptionally high grade finish and one capable of withstanding hard wear and usage, and injury by contact with ordi- Signed at Dubuque this 12 day of Aprihg. I