US1945537A - Artificial fabric - Google Patents

Description

PATENT OFFIE ARTIFICIAL FABRIC George L. Schwartz, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application May 31, 1930, Serial No. 458,899. Renewed January 19, 1933 6 Claims. (CI. 9221) This invention relates to a new type of artificial fabric, more specifically a fabric manufactured from a fibrous cellulosic base preferably prepared by a certain mode of chemical treatment, and by the impregnation of starch in said base material.

The incorporation of starch in paper has been known in the prior art, such processes consisting generally in either passing the finished paper web through a suitable solution of starch or size or similar material, or by mixing the size with the fibrous cellulose before depositing the web. I have found, on studying these methods of preparation, that the product so produced is not profoundly affected by the incorporation of starch in respect to the resistance against tear and similar properties possessed by the paper, although in certain respects the paper is improved by the incorporation of starch. I have found that when incorporating a solution of starch in, for example, kraft paper, there is a certain degree of improvement in the resistance against tearing, as more fully hereinafter set forth. However, the preparation of a fabric having quite pronounced resistance against tear and abrasion, together with other desired qualities, has not been achieved by the aforesaid methods.

It is an object of this invention to manufacture an artificial fabric from a fibrous cellulosic base by the absorption therein, in a suitable manner, of starch or analogous substances, to produce a'fabric having the characteristics of flexibility, resistance to tearing and abrasion, good aging qualities, and improved paper-break qualities as compared with similar fabrics heretofore produced.

These objects are accomplished by the production of an article according to the preferred process hereinafter recited, although it will, of course, be understood that it is not intended to limit the invention to the process described:

By way of one illustration of the invention we begin with a certain type of fibrous cellulose pulp, which maybe described as an artificially crinkled fibrous cellulosic material produced by the treatment of fibrous cellulose with alkali in certain concentrations, as more particularly recited in McCormick & Schwartz application Ser. No. 283,445, filed June 6, 1928, of which Patent 1,857,100 is a continuation in part. A brief description of this process for treating the fibrous cellulose is as follows;

Wood or other suitable fibrous cellulosic pulp is prepared in any suitable manner and is then treated with caustic alkali, for example, sodium, potassium, or lithium hydroxide, in aqueous solution at a concentration of from 8% to 35 at room'temperature for a short period of time insufficient to cause gelatinization of the cellulose fibers. This time treatment is generally a matter of only several seconds to thirty minutes, the preferred practice being todisperse the pulp with the caustic without cutting action at high pulp consistencies (low ratio of liquor to pulp), such as is disclosed in the examples of the men tioned application and patent, in order to minimize the effect of time action of the strong caustic on the pulp. The caustic solution, when the pulp is completely wet therewith, is diluted with water to stop the reaction. On removal from the alkaline solution the fibers are thoroughly washed with water and are then found to be in the altered condition, exhibiting the appearance of having a crinkle as compared with the original condition.

This so-called fibrous cellulose 01' fibrous cellulosic material is then made up in the form of a wet pulpin a suitable receptacle, as, for example, in our present practice we take a tub and place therein a fibrous cellulose pulp in the proportion of 130 grams of pulp (on a dry basis) and 57 kilos of water. To this pulp, so diluted, are added 40 to 90 grams of cornstarch in the form of a 2 aqueous solution. The starch solution is then mixed with the pulp by suitable. agitation. It is thereafter deposited in the regular manner to form a sheet of fibrous cellulosic fabric. Standard apparatus in the paper-manufacturing industry may be used for this operation. The water will, of course, drain off from the deposited cellulose fibers, but we have found that the starch is adsorbed by them. After the sheet is formed, it is dried and calendered and is then ready for any subsequent treatment for use to which such an article is adapted.

I have found that glucose, dextrine, casein, and similar gelatinous and colloidal materials may be incorporated with the starch, for example, in equal proportions by weight to produce advantageous results. For example, when glucose is added in equal part by weight to the above set forth proportion of starch, there will be produced a fabric having a much increased resistance against tear as compared with a fabric having only starch incorporated'therein. The proportions of glucose, etc., may be varied to a considerable extent while still retaining this marked advantage.

The addition of glucose, dextrine, casein, etc., may be made at the same time that the starch ;is added into the tub or mixing device and thoroughly mixed with the cellulose. The mode of addition of the ingredient used to supplement the action of the starch is not, however, of particular importance as long as it is simply necessary that the added ingredient be combined with the starch when the sheet is formed. 1

Theproperties of the resulting fabric are very marked. As measured upon the Elmendorf tester, the resistance against tearing ranges as high as 1200 and even higher, as compared with the value of 180 for the sheet made from crinkled fibers not impregnated with starch. The marked effect of starch "with and without glucose, dextrine, etc., is therefore quite evident, and it should be furthermore emphasized in this connection that glucose, dextrine, casein, etc., in and for themselves have no such advantageous effect upon the fabric, as we have found that when they are added without the presence of starch they will not produce a fabric resistant against tear beyond the inherent resistance of the fabric itself. The high value of 1200 on the Elmendorf tester should also be compared with the value of 460. for ordinary kraft paper and against the value of approximately 635 for such kraft paper impregnated with starch, as in the herein-described process. It will therefore be seen that the use of this particular type of alkali-treated paper with starch produces a very unexpected result, with marked advantages in many'arts and uses. By way of further illustration of the range of resistance against tear, it may be stated that when the aforesaid crinkled or alkali-treated cellulose has been prepared originally from a kraft paper, the

basis of a paper weight of .87 lbs.- per area of 36 inches by 40 inches, as this represents a standard type of article.

Among the other properties of the articles herein produced are flexibility, the property of showing a relatively small paper-break when bent or sharply flexed, the strong resistance against tear and resistance to abrasion, and good aging qualities. used in the book-binding art it has been found that it cuts easily like leather without leaving a paper-making steps.

frayed edge. The pliability is also better than ordinary kraft paper of similar strength. It will be evident that, where sheets are made of starchimpregnated paper having-other specific paper weights, the resistance against tear and other physical constants will be proportionately altered.

The articles here introduced are useful for book-binding, base materials for linoleum, base for wall coverings, auto top materials, auto interior coverings, furniture coverings, window shades, materials entering into the construction of shoes, and analogous uses wherein fabrics find employment.

It should also be pointed out that this particular fabric is not laminated but consists of a single deposited sheet impregnated with starch, etc. It has been found, however, that a laminated sheet may be made by gluing together sheets as herein described or by putting on a multiple deposit in Furthermore, instead of laminating, the sheet may be made thicker than herein described so as to constitute a single deposited article equalling in its thickness a multiple deposited or a laminated sheet and thereby securing advantages in flexibility and structural strength not possessed by laminated sheets of equal dimensions. advantage of this invention.

I have found that the kind'of starch used does not appreciably affect the quality of the product.

Furthermore, in the article- The latter is a particular In addition to corn starch, I, have found gloss or laundry starch, wheat starch and tapioca starch, to be effective.

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 I do not limit myself to the specific embodiments thereof except as de fined in the appended claims.

Iclaim:

1. An article of manufacture comprising a sheet of artificially crinkled, fibrous cellulosic material having starch absorbed therein said article being flexible, exhibiting very little paper-break and having strong resistance to tear, said artificially crinkled cellulosic material being substantially identical with that obtained by dispersing paper pulp with 8% to 35% sodium hydroxide solution at room temperature and promptly washing out the caustic.

2. An article of manufacture comprising a sheet of artificially crinkled fibrous cellulosic material having starch and glucose absorbed therein, said article being flexible, exhibiting very little paperbreak, and having a strong resistance against tear, said artificially crinkled cellulosic material being substantially identical with that obtained by dispersing paper pulp with 8% to 35% sodium hydroxide solution at room temperature and promptly washing out the caustic.

3. An article of manufacture comprising a sheet of artificially crinkled fibrous cellulosic material having starch and another colloidal material absorbed therein, said article being flexible, ex-

hibiting very little paper-break, and having a strong resistance against'tear, said artificially crinkled cellulosic material being substantially identical with that obtained by dispersing paper pulp with 8% to 35% sodium hydroxide solution at room temperature and promptly washing out the caustic.

4.. The process of manufacturingan artificial fabric comprising preparing a pulp of artificially crinkled cellulose in the proportion of about 130 grams pulp (drybasis) to 57 kilos water, adding thereto a dilute aqueous starch solution in the proportion of 40 to 90 grams dry starch, mixing the starch solution with pulp, depositing the pulp to form a sheet having the starch largely adsorbed therein, and drying, said pulp being substantially identical with the pulp obtained by treatingwood pulp with. 8% to 35% sodium hydroxide solution at room temperature for a time not longer than 30 minutes. i

5. The process of manufacturing an artificial fabric which comprises dispersing wood pulp at high pulp consistencies with caustic alkali having a concentration of between 8% and 35% for a time not longer than 30 minutes, mixing an aqueous starch solution with a pulp of the treated