US1892658A - Treating wood - Google Patents

Description

Patented Dec. 27, 1932 UNITED STATES PATENT OFFICE PETER J. WIEZEVICH, OF ELIZABETH, NEW JERSEY, ASSIGNOB TO STANDARD OIL DEVELOPMENT COMPANY, A CORPORATION OF DELAWARE TREATING WOOD 1T0 Drawing.

This invention relates to an improvement in the treatment of wood, compressed fiber boards and the like, with mineral waxes whereby resistance of the products to the ac- 5 tion of water is greatly improved.

The impregnation of wood with high melting waxes is now common practice and the various features of this treatment have been described in the patent and other literature.

Wood preferably after being thoroughly dried is immersed in a bath of molten high melting wax such as Montan wax with or without the application of pressure and a product of markedly superior properties such as ease of polishing, resistance to warping, cracking, decay and the like, is secured. Montan wax, which is especially suitable for this treatment, is a mineral wax which is usually imported and is produced by extraction of lignite and pyropissite with suitable solvents. Other waxes such as carnauba and candelilla, hardened Montan wax' such as Romalin wax, or high melting parafiin waxes from petroleum, may be used in place of the Montan wax. The wax may be used in admixture with suitable solvents and penetrating oils such as cylinder oil, heavy naphtha and the like, an especially desirable composition being a heavy paraflin distillate from certain wax-containing petroleum crudes. This distillate contains both wax and oil in suitable proportions for wood impregnation. The wood may also be impregnated, either prior to or in conjunction with the wax or wax and oiltreatment, with fireproofing agents such as sodium biborate, paradichlorbenzine, and the like, and with toxic agents or preservatives such as creosote, beta naphthol, sodium floride, zinc chloride, aluminum sulfate, arsenic compounds, borax and the like; These various agents may also be added to the wood prior to the wax treatment.

While the wax impregnated woods possess highly desirable properties they nevertheless generally possess the disadvantage that white blotches appear on the surface of the wood wherever it has been allowed to come in contact with water for an appreciable length of time. For example, woods im- Application filed December 21, 1931. Serial No. 582,500.

pregnated with Montan or'high meltin petroleum waxes are very desirable for 00ring because they do not warp and are easily maintained in a highly polished. condition. However, white blotches appear on suchflooring wherever water is spilt on it and these blotches can be removed only by very vigorous polishing.

A method of rendering wax impregnated wood resistant to the action of water has been disclosed in co-pending application No. 57 0,974, filed October 24, 1931, by Charles W. Mudge. In this process the wood is contacted with a diluted aqueous solution of an acidic treating agent with or without the application of pressure prior to the wax impregnation treatment. With such processes involving a pretreatment with an aqueous solution it is generally preferable to dry the wood very thoroughly before subjecting it to 7 the wax impregnation treatment. An object of the present invention is to render the wax impregnated wood resistant to the bleaching action of water, by a treatment in which the wetting of the wood with water or aqueous solution is not required. The wood may be subjected to the wax impregnation step either concurrently with or subsequent to this improved treating step.

I have now found that treating the wood with an acid gas such as chlorine, bromine, hydrogen'chloride, sulfur dioxide, or other acidic gases renders the wood after wax impregnation resistant to the action of water so that no spotting or bleaching occurs even when the wood is contacted with water for I. long period of time or when water is spilled upon and allowed to evaporate from the surface of the wood under atmospheric conditions.

My invention will be understood from the following example which is illustrative of one method of operation:

Slabs of Southern yellow pine after thorough drying and planing are exposed for a 95 short period \of time, approximately one minute, to gaseous chlorine at ordinary atmospheric temperature and pressure. The wood is then impregnated in the ordinary manner with a high melting wax or a mixture of such wax in oil, with or without the application of pressure. The wood after this treatment takes a high polish readily and shows no tendency towards spotting or bleaching when contacted with water. The above treatment with gaseous chlorine may be conducted if desired directly on the freshly cut green wood or at any stage in the drying proxess. 'ith highly reactive gases such as chlorine, bromine. or the like. care must be taken not to expose the wood for too long a time. as otherwise discoloration or charring of the wood may result. I-lowever, a slight excess of the reagent produces a tinish that in some instances may be desirable. For example, the wood maybe given an ebony finish by treatment with chlorine gas. The grain of the wood may also be. emphasized by careful treatment.

The acidic gas may be used in a highly concentrated or substantially pure form. as described above. or it may be diluted with various inert gases such as nitrogen. methane, air and the like. The preferred time for treatment will depend to some extent upon the nature of the wood. and upon the treating temperature, pressure. coneentratimi and type of acidic gas used. and will be somewhat longer if a diluent gas is used. The use of elevated temperatures during the contacting of wood with acidic gas is not generally necessary but may be used if desired and the time of treatment may be materially decreased thereby. Mixtures of the acidic gas and a diluent are especially preferred when it desired to conduct this step under pressure so that the wood may be thoroughly impregnated with the acidi agent. Such pressure treatment is especially advantageous when this treating step is conducted before the wood is cut and planed to shape for the wax impregnation step, since the treating gas then penetrates into the interior of the wood and subsequent operations such as cutting, planing, etc. do not necessitate further pretreatment.

It is preferable to dry the wood thoroughly, cut and plane it to the desired dimensions and then treat it with an acidic gas prior to the wax impregnation step. Under some conditions theacid gas treatment and the wax impregnation may becomhined. For example, in wax impregnation of wood it is customary to subject the wood in sealed drums to pressure with air and then to force the liquid wax-containing mixture. heated to a temperature insufiicient to char the wood. into the drum until the wood is completely immersed. The unabsorbed liquid is then withdrawn. and the pressure is released ,preferably after cooling the wood at least below the melting point of the wax used, or of the treating mixture. In this treatment a small amount of acidic gas, say 1 to 5% may be added to the air used and the wood is thereby thoroughly impregnated with the treating agent and on completing the wax impregnation treatment shows the same desirable characteristics. such as resistance to the bleaching action of water, as already described. (are should also be taken in conducting this operation that the acidic gas is not permitted to react with the wood to too great an extent since such a treatment may cause a marked deterioration in both the. strength and color of the finished product.

My invention is not to be limited to any theory of the operation of my process nor to any illustrative examples. but only by the following claims in which I wish to claim all novelty insofar as the prior art permits.

I claim:

1. An improvement in the process of impregnating wood, fiber board and the like with compositions in which Montan or a similar high melting wax is a major ingredient which comprises subjecting the wood to a pretreating step comprising contact with an acidic gas.

2. An improvement in the process for impregnati'ng wood, fiber board and the like with a high melting wax which comprises subjecting the wood to a pretreatment comprising contacting the wood with an acidic gas.

Process according to claim 2 in which the acidic gas is hydrogen chloride.

4. Process according to claim 2 in which the acidic gas is chlorine.

Process according to claim 2 in which the acidic gas is diluted with an inert gas.

6. Process according to claim 2 in which the pretreatment is conducted with a gaseous mixture of an acidic compound and an inert gas at superatmospheric pressure.

7. An improved process for impregnating wood with high melting wax compris ing subjecting the wood to contact with a mixture of hydrogen chloride and air at an elevated pressure. immersing the wood while under such pressure in a bath comprising a molten high melting wax at a temperature insuflicicnt to char the Wood, withdrawing the unabsorbed molten wax, cooling the wood and subsequently releasing the pressure.

PETER J. WIEZEVICH.