US2855369A - Stain and method of application - Google Patents

Description

STAKN AND METHOD OF APPLICATION Russel ll). Hamilton, Detroit, Mich., assignor to Chadeloid Corporation, Dayton, Ohio, a corporation of Delaware No Drawing. Application December 2, 1955 Serial No. 550,783

1 Claim. (Cl. 252-3013) This invention relates to a new and novel wood stain and to a method of producing the same, and is related to copending application Ser. No. 251,999, filed October 18, 1951, now abandoned.

It is an object of this invention to provide a stain of excellent coloration properties containing a monovalent metal salt of a carboxy alkyl cellulose and a dye which functions to enhance the brilliancy of the stain and improve its staining power.

It is a further object to provide a method of incorporating monovalent metal salt of a carboxy alkyl cellulose into a Wood stain together with brightening agents.

It is a further object of the invention to provide a process of staining and a stain that will improve the appearance of the stained wood, particularly in sunlight.

It is a further object to be able to bring out the configuration of the grain of the wood, to give greater depth to the appearance of the stained wood so that it will have a rich, full bodied and sparkling quality and to further be able to utilize lower grade woods by improving their staining quality and appearance and the definition of their grain. In lower grade woods it is found that the grains are not as distinct and there is greater monotony as compared with the finer woods in which the grain stands out and, therefore, presents a handsome appearance when stained and finished.

It is also an object to place this brightening agent so that it would combine with the other dyes either when it had been put upon the wood and the wood was coated with these dyes to stain it 01 the brightening agent is put into the dye combination of the stain so that there is only one application. In either event the result has been a marked improvement both in the initial appearance of the wood and in the subsequent life of the wood after finishing.

Heretofore in the art, the problem has been two-fold in connection with wood stains: first, the aging of the wood finish in sunlight causing it to darken and the wood grain to lose its definition, depth, etc. This eliminated the natural contrast between the grain and the rest of the wood and depreciated the appearance of the wood, giving it a uniform dull, dark color. It has also been a problem in finishing Wood not to over-finish it in that the multiple number of treatments such as filling, staining, sealing, lacquering, rubbing and polishing, while they built up at the beginning the life of the wood a handsome appearance, yet as the Wood aged these multiple coatings also aged and became dull, in turn dulling the finishes of the wood.

Derivatives of cellulose of low and medium viscosity such as the monovalent metal salts of carboxy alkyl cellulose, for example, sodium carboxy methyl cellulose, have relatively good solubility in water but are substantially insoluble in the organic solvents. Accordingly, these materials have not been considered to be useful in conjunction with wood stains where the presence of water is generally undesirable as this solvent leads to raising of the grain of the Wood. Further, a difficulty encountered with a stain containing carboxy alkyl cellulose has States Patent 2,855,369 Patented Oct. 7, 1958 been the relatively deep, dull color of the stain produced. The present invention overcomes this difliculty and provides a Wood staining composition having improved coloring characteristics.

It has been found that the monovalent metal salt of a carboxy alkyl cellulose may be effectively employed in producing stains if the cellulose derivative is reacted in solution with an inorganic compound capable of yielding a colored ion, the reaction between the inorganic compound and the carboxy alkyl cellulose effecting a colored precipitate. This precipitate is substantially water-insoluble and soluble in most organic solvents only with the greatest difficulty. However, it has been found that if the precipitated material is treated with tetrahydrofurfuryl alcohol containing less than about 1.0% of a strong alkali that solution forms an effective wood staining composition. The solution may be thinned as required with methanol, toluol, or xylol, which are compatible with the precipitate and the resultant material may then be employed as a stain for wood. The effectiveness of the resultant staining solution is enhanced when applied on woods since the carboxy alkyl cellulose salt has a tendency to inhibit grain raising.

The optical brightening agents are usually water white and transparent and therefore have not interfered with the Water-soluble aniline dyes or oil-soluble dyes used to stain the wood and they do not discolor the filler. When used they give the effect with the minimum of finishing operations of a highly finished piece of wood.

The optical brighteners which have been found useful are the coumarin derivatives, such as beta-methylumbelliferone; the stilbene derivatives and other brighteners that are colorless dyes, fluorescent, direct dyestuffs with an atfinity for cellulose. This gives to wood and wood stains an increased surface reflectance and a more brilliant surface than an untreated surface. Hydroxy coumarin; 1-naphthylamine-4-sulfonic acid, Na 2-naphthylamine-6, 8-disulfonate; dibenzoylaminostilbene sulfonic acid derivative; naphthalene; benzimidazole, such as 2-styrylbenzimidazole or l-(m-acetamido-Z-benzimidazole)-2-(pacetamidophenyl) ethylene; triazine condensation products; 2,2-ethylenebis (l-benzylbenzimidazole). For cellulose materials, the following have been found to be useful: o-ethoXy-benzoyl derivatives of 4-,4-diamino-stilbene- 2,2-disulfonic acid, and o-ethoxy-benzoyl derivatives of 4,4-diaminostilbene-2,2-disulfonic acid, the disodium sulfonate of 4,4'-di (o-ethoxy-benzoyl-amino) stilbene 2,2-'-disulfonic acid being especially useful.

I prefer beta-methyl-umbelliferone which is a hydroxymethyl coumarin that is compatible with the organic solvents used. Styrylbenzimidazole is also useful as well as 4-methyl-7-diethylamino coumarin.

In some instances the standard beta-methyl-umbelliferones were precipitated in stain solutions. In such an event, when placed in their proper solvent, they can be used to treat the wood before staining. They are not used in the stain, filler or finishing coats.

The following are typical examples which we have used for successful brightening of Wood and wood stains. We have found that the treatment of the Wood first in a suitable solvent emphasizes the grain of the wood. However, the addition to any coat, if soluble in that particular phase, enhances the reflectance and luminescence of the wood in those cases where enhancement of the grain effect is not as important. When used in the top coat with the stains there is a more pronounced elimination of the tendency of the woods to yellow and dull under their coatings. Woods as heretofore treated with wood stains, as they age, tend to yellow and darken into browns and reds and in the case of blond woods to dull. We have found the top coating with the optical brighten ers introduces a blue cast which is not apparent to the eye but negatives this ageing, yellowing and browning effect.

The invention will be more fully understood by reference to the following specific examples, the parts being by weight unless otherwise stated:

Example 1 Two parts by weight of low viscosity sodium carboxy methyl cellulose were dissolved in 100 parts by weight of water with rapid agitation and at room temperature (approximately 70 F.). Care was exercised to avoid lumping of the solute.

A saturated solution of ferric sulfate in water was then prepared by adding an excess of the salt to the water and thoroughly agitating. A suitable solution may be made using 100 grams water per 25 grams of ferric sulfate. The ferric sulfate dissolved very slowly but forms a fairly concentrated solution in a short time, which period varies with the degree of agitation and the fineness of the salt. The solution of ferric sulfate was then separated by filtration from the undissolved excess of the salt.

The resultant water solution of the carboxy methyl cellulose was then added to 40 parts of the saturated ferric sulfate solution slowly and with constant agitation. A voluminous brown precipitate appeared which settled out slowly. This precipitate was then carefully washed with water and dried. The precipitate has a dark brown and resinous appearance.

Example II A wood staining composition is prepared as follows:

To 100 parts of the dried brown precipitate of Example I there is added 100 parts of tetrahydrofurfuryl alcohol containing about 0.5% by weight of sodium hydroxide. The precipitate dissolves slowly in the alcoholalkali solvent, agitation being employed to assist in dissolving the precipitate, forming a brown colored staining solution.

To each 100 parts by weight of the resultant brown colored solution there is added 50 parts by weight of methanol andv 0.1 part by weight of beta-methyl-umbelliferone (7-hydro'xy-4-methyl coumarin).

The stain thus formed may be applied to a wood surface in the manner known to the art, giving the wood a vivid uniform brown coloration.

Example III A wood staining solution is prepared as described in Example II, except that in place of methanol a 50-50 by volume mixture of methanol and toluol is used as the solvent thinner and to which'is introduced 0.2 part by weight of styrylbenzimidazole as the brightening agent.

Example IV In this example a staining solution prepared as in Example II is thinned with toluol or xylol alone employing in this instance approximately 40 parts by weight solvent thinner to which is added 0.15 part by weight of 4-methyl-7-diethylamino coumarin, and 100 parts by weight of the brown colored staining solution to provide a suitable wood staining solution.

The use of toluol or xylol as a solvent thinner is generally preferred for staining close grain hard woods.

Example V A wood staining solution is prepared as described in Example II, wherein in place of beta-methyl-umbelliferone there. is substituted the disodium salt of 4,4'-di (o-butoxybenzoylamino) stilbene-2,2-disulfonic acid.

It may be noted that other ferric salts having a greater water solubility may replace ferric sulfate in the above composition.

These water soluble stains so produced are compatible with the optical brightener dyes as aforementioned and which are introduced thereto in effective amounts to produce a blue cast as heretofore pointed out. These dyes are substantially water white and are solvent in the same solvents as these stains formed from carboxy methyl cellulose.

In each case the initial stain solution has added to it the optical brighteners, e. g. styrylbenzimidazole, betamethyl-umbelliferone, amino-naphthalimid, hydroxymethyl coumarin and stilbene, particularly the derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid, such as the alkali metal salt of 4,4'-di (ortho or para aminobenzoylamino) stilbene 2,2-disulfonic acid.

Example VI Three grams of sodium carboxy methyl cellulose are first dissolved in 100 grams of water as set forth in Example I.

Approximately 20 grams of anhydrous copper sulfate may then be dissolved in water to form a substantially saturated solution of the salt. Copper dissolves more readily than the ferric salt and accordingly agitation may be eliminated if desired but is generally preferable to speed formation of the solution. Filtration is not required.

The carboxy methyl cellulose solution may then be added slowly to the salt solution and a blue precipitate begins to form almost immediately. This precipitate is then washed with water and dried.

To 100 parts by weight of the dried blue precipitate of Example II is then added parts of tetrahydrofurfuryl alcohol containing approximately 1% of sodium hydroxide by weight. The resultant blue solution is then thinned with methanol as set forth in Example II into which has beenintroduced 0.1 part by weight of betamethyl-umbelliferonc.

Example VII A solution containing approximately 2 grams of sodium carboxy methyl cellulose is prepared as set forth in Example I.

A green solution, containing 15 grams of anhydrous chromic chloride and a very small amount (0.5 gram) of chromous chloride, as reducing agent, is introduced into grams of water. The presence of the chromous salt assists the solution of the chromic chloride to such extent that agitation is not required.

The chromic chloride solution is then combined with the solution of the salt of the cellulose derivative as set forth in Example I to obtain a greenish precipitate which is filtered out and washed with water and dried.

Approximately grams of tetrahydrofurfuryl alcohol containing 0.8% by Weight of sodium hydroxide are then combined with the precipitate (100 parts) to form a green stain'which is thinned as described in Example II, in thisinstance to each 100 parts by weight of the resultant green solution there is added 50 parts by weight of methanol and 0.1 part by Weight of the sodium salt of 4,4 di (o amino benzoylamine)stilbene 2,2 disulfonic acid.

The above examples are set forth by Way of illustration only since inorganic salts which have a fair solubility in water and which in solution yield an ion of a desired color may be reacted with the sodium carboxy methyl cellulose to form a complex salt and are considered to be within the inventive concept.

It should also be noted that the concentration of alkali used with the tetrahydrofurfuryl alcohol should be kept low as an amount greater than about 1% may tend to drive the reaction product of the cellulose derivative and the inorganic salt in the reverse direction.

It will be understood that the brighteners mentioned hereinbefore can be used singularly or in combination with each other.

It will be understood that while there have been given herein certain specific examples of the practice of this invention, it is not intended thereby to have this invention limited to or circumscribed by the specific details of materials, proportions, or conditions herein specified, in view of the fact that this invention may be modified according to individual preference or conditions without necessarily departing from the spirit of this disclosure and the scope of the appended claim.

What is claimed is:

A wood staining composition consisting of the reaction product of chromic chloride and sodium carboxymethyl cellulose dissolved in alkaline tetrahydrofurfuryl alcohol containing 0.8% of sodium hydroxide, and sodium salt of 4,4-di(o-amino-benzoylamine)stilbene-2,2-disulfonic acid.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,703 Ackerman Sept. 1, 1953 2,341,009 Axelrad Feb. 8, 1944 10 2,654,713 Fleck Oct. 6, 1953 2,691,596 Nack et a1. Oct. 12, 1954