US2000689A - Wood staining - Google Patents

Description

Patented May 7, 1935 STATES PATENT OFFICE Charles J. Pedersen,

. ware No Drawing.

7 Claims.

This invention relates to the staining of fibrous materials and more particularly to the production of stains by the catalytic oxidation of organic compounds on said fibrous materials.

Heretofore wood has been stained by one or two general methods. By the first method the wood to be stained was treated with dye solutions to allow it to absorb the dyes. The great objection to the use of this method has been the poor penetration attained.

By the other method the staining has been accomplished by the oxidation of aromatic organic compounds on the wood fibres, the oxidation being brought about by the use of chemical oxidizing agents in the presence 01 mineral acids. The disadvantages of this last named method were the resultant tendering oi the wood and the effiorescence of the resultant compounds'on the surface of the wood.

This invention has for an object the production of a stain with great penetrating power and insolubility. A further object is the staining of fibrous materials without use of chemical oxidizing agents and mineral acids. Still further objects are the production of a material adapted for rapid staining of wood, the production of a very fast stain, a very deep stain, a stain which is unaccompanied by tendering of the fiber, a stain which is unaccompanied by emorescence and in general an advancement of the art. Other objects will appear hereinafter.

These objects are accomplished by this invention by which certain substituted amines or diamines are catalytically oxidized on or in the material to be stained. The invention will be readily understood from a consideration of the following examples in which the parts are given by weight.

Example I There wasdissolved in '15 ml. of the monoethyl-ether of ethylene glycol 1 gm. of cupric chloride, and to the solution was added 25 ml. of toluene. Fifteen (15) gms. of m-toluylene diamine was dissolved in the resultant mixture. A piece of wood was heated to the temperature of 150 F. and then dipped into the solution while still warm. The wood was allowed to soak for 30 minutes after which it was withdrawn wiped, dried and finished. In the examples carried out it has been found that cooling the. wood in the solution greatly aids the penetration of the stain.

Example II In this example all figures are based upon the original weight of the alcohol. To a 1% solution Carneys Point, N. J., assignors to E. I. du Pont Wilmington, DeL, a corporation of Delade Nemours & Com- Application December 23, 1930, Serial No. 504,426

(Cl. 91-68) A Example III A sample of wood was first soaked in a 15% solution of m-toluylene di-amine in alcohol. Thereafter the surface liquid was wiped off and the wood dipped into a 1% solution of cupric chloride in alcohol. Oxidation started imme diately at the surface and althoughthe color developed below the surface of the wood somewhat slowly due to therate of diffusion of the air to the interior of the wood, the visible portions of the wood were stained even when scraped to the depth of the penetration of the m-toluvlene diamine.

Other organic compounds than the m-toluylene di-amine of the above examples may be used satisfactorily. In general other aromatic di-amines, for example, m-phenylene-di-amine, p-phenylene-di-amine, and m-naphthylene-di-amine, are suitable. There may also be used aromatic amines which are characterized by containing activating or positive groups, for example, the hydroxyl, the alkoxy and amino groups in the ring and containing no n'e'gative groups or substituents, such as, the carboxyl, the sulphonic and nitrile groups in the ring. As examples of suitable compounds of this class there may be mentioned p-amino-phenol and p-amino-anisole. As examples of aromatic amines which are unsatisfactory because of negative groups in the ring may be mentioned sulfanillc acid, anthranilic acid and -chloro-m-toluidine-p-sulphonlc acid.

The term negative substituent as used in this application has its usual meaning, namely, that it tends to increase the negative character or decrease the positive character of the molecule of which it is a part. The unsubstituted aromatic amines, for example, aniline and the toluidines have not been found oxidizable under the conditions described.

It is sometimes desirable to add a wetting agent to the staining composition in order to obtain better penetration as for example sulfonated castor 011, one of the alkylated naphthalene sulfonic acids sold under the trade name of Nekal or tri- 'ly in order to meet particular conditions.

ethanolamine oleate or other ethanolamine soap. Catalysts other than the cupric chloride of the examples are suitable. In general any soluble cupric salt, for example, cupric acetate may be used. The soluble salts of vanadium are suitable.

The invention is not limited to those solvents mentioned in the above examples, for example, benzene and acetone, give satisfactory results. In general any organic solvent which may be classified as miscible or immiscible with water is suitable. Water itself may be used in cases where it is not harmful to the success of the process. The disadvantages of using water are that it causes swelling of the wood and therefore requires considerable time for the wood to regain its normal dimensions in order that it may be further processed. Another objection to the use of water is present in the case where the wood to be stained contains glued joints. The water loosens the joints.

' Inthe case where the material to be stained is not swelled by water its use as a solvent is quite satisfactory especially with the more soluble compounds such as m-phenylene di-amine and the like.

-' All of the solvents covered by the above description may be generally divided into two' classes known as polar, that is, one in which ionization takes place and non-polar, that is, one in which ionization is not appreciable, solvents.v Where polar solvents are used the basicity of the amine or di-amine substance may cause precipitation of the catalyst and it is therefore necessary to add "to the solution a material which will causeretenthe invention is broadly applicable to fibrous ma 'terials. Mention may be made of asbestos, wool, paper, paper pulp and fur. v

The method of application may be varied wide- For instance in the process of Example HI the order of application of the materials may be reversed. In other instances better and more rapid penetration may be secured by applying the stain producing compound under pressure. The penetration can be varied to the desired degree by the time of soaking. The method of drying may be modified as required by specific situations. same generality applies to the concentration of the solutions used in the process and the temperature for the drying.

This invention has numerous advantages as will be obvious from a consideration of the specification. Because organic solvents are used wood articles comprising joints held together by water soluble glue may be stained satisfactorily. Furthermore, use of solvents of this character because of their high volatility results in quick drying of the material (30 minutes penetration of these compositions being equivalent to several hours penetration of the compositions heretofore known) and consequently permits rapid processing. *Rapid processing is ,further aided by the fact that these solvents do not swell the wood being treated (as does water) and therefore the time required to allow an article to regain its normal size is eliminated. 'Because no The mineral acids are used in this invention tendering of the fibers of the materials stained is avoided. Because of the absence of chemical oxidizing agents in the process efilorescence, on the stained article is not present. Another great advantage of the invention is that the stains produced are extremely fast and are not extracted by any ordinary method. Still another advantage is present in the fact that the grain of the wood stained according to this invention is not obscured.

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. The process of staining Wood which comprises treating the wood with a composition of matter comprising an organic solvent selected from the group consisting of alcohol, the monoethyl ether of ethylene glycol, benzene, acetone and toluene, a member selected from the group consisting of m-toluylene-diamine, m-phenylenediamine, p-phenylene-diamine, m-naphthylenediamine, p-amino-phenol, and p-amino-anisole, and cupric chloride, and thereafter exposing the treated material to the action of air.

2. The process of staining wood which comprises treating the wood with a solution of cupric chloride in alcohol and aqua ammonia to which has been added m-toluylene-diamine, and thereafter exposing the treated material to the action 'of air.

3. The process of staining wood which comprises treating the wood with a solution of mtoluylene-diamine in alcohol, subsequently treating the wood with a. solution of cupric chloride in alcohol, and thereafter exposing the wood to the action of air. v

4. A composition of matter comprising an organic solvent selected from the group consisting of alcohol, the mono-ethyl-ether of ethylene glycol, benzene, acetone and toluene, a member selected from the groups consisting of m-toluylenediamine; m-phenylene-diamine, p-phenylenedlamine, m-naphthylene-diamine, p-amine-phenol, and p-amino-anisole, and cupric chloride, the ingredients being in proportions which, on exposure to air, impart a stain to wood impregnated therewith.

5. A-composition of matter'comprising a solution of cupric chloride in alcohol and aqua ammonia to which has been added m-toluylene-di- 'an aromatic mono-amine having a positive group substituted thereon and an aromatic diamine having a positive group substituted thereon in a solvent inert to the fibrous material, in another operation impregnating the fibrous material with an oxidation catalyst in a solvent inert to the fibrous material, and exposing the treated material to the action of a gas containing free oxygen.

CHARLES J. PEDERSEN.