US2008432A - Manufacture of vulcanized fiber - Google Patents

Description

Patented July 16, 1935 2,008,432 MANUFACTURE OF VULCANIZED FIBER John K. Anthony, Cleveland Heights, Ohio, assignor to Horace B. Fay, Cleveland, Ohio No Drawing. Application August 29, 1931,

- Serial No. 560,248

5 Claims.

Hydrated cellulose sheets, such as prepared by subjecting cellulose or paper to the action of zinc chloride or like agent, forming the so-called vulcanized fiber, is subject to the serious disadvantage of warping and cockling, such as to quite materially change its shape and contour, and rendering it impossible of application in certain usages where its other properties would be desirable. -I have found that this distortion-tendency is associated with the fibrous structure which is perpetuated in the sheet, customary methods of manufacture being careful to merely slightly gelatinize the fibrous structure without destroying the fibrous condition in which the unit fibers lay at angles to each'other. Such fibrous structureis hygroscopic and has a variable rate of expansion and contraction, this being particular- 1y effective longitudinally of the individual fibers, and where these are opposed, corresponding angular stresses are set up. The resultant distortion is more serious the thinner the sheet. In accordance with the present invention however, it now becomes possible to make sheet material in which the excessive unit cross-stresses are eliminated, and with corresponding effect in uniformity of contour and plane in the sheet material.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description setting forth -in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the invention may be employed.

Cellulose fibrous material, desirably the purer the better, is prepared by beating in a paper- .mill type of beating engine.. Where operating for example with cotton rags as material, such stock may be beaten to smoothness, after having been preliminarily cooked if desired with a soda,

solution. If desired, the stock may be bleached conveniently, .while undergoing the beating treatment. The material from-the beating engine is sheeted out on a paper machine, cylindertype or Fourdrinier, and is formed to desired thickness, and is dried. The sheet material is then treated in a bath of concentrated zinc chloride solution, for instance a solution of about 70 B. Instead however, of drawing the web through on its own strength by reason of the perpetuation of the fibrous structure as heretofore customary, I maintain the cellulose in the bath long enough to substantially obliterate or amorphize the fibrous structure. This will involve an exposure of for instance 4-8 minutes or more, depending upon the thickness of the stock, and temperature, as well as the concentration of the bath, etc. The stock may be supported by a suitable 5 surface or conveyor, so as to avoid tearing in its then weakened condition. Surplus solution is removed by squeegee rolls' or the like, and the stock is set, and is washed t'oremove residual zinc chloride, the washing being continued until the chemical is substantially completely removed.

-' The cellulose material is then dried and finished.

In the conversion treatment of the cellulose, other agents may, of course, be employed, instead of zinc chloride, this being a convenient and efficient material. For instance, the other halogen salts of zinc are applicable in some instances, and sulphuric acid may likewise be employed. In all cases, in contradistinction to practice heretofore, the treatment, it will be noticed, is carried out such as to extinguish the predominant fibrous structure characteristic and provide a mass in which individual embedded units of dissimilar angle cannot set up individual crossstresses. To this extent, the precise nature of the cellulose converting agent or gelatinizing substance, is not directly material, and in some instances I may employ successive treatments of diverse agents,the latter of which finally extinguishes the fibrous structure to the extent desired. For instance, the cellulose sheet material may be first treated with zinc chloride solution or sulphuric acid, or the like, and after washing with such treating chemical, may then further be treated with a cellulose gelatinizer such as a cupro-ammonium solution, sufliciently to eliminate the fibrous structure to the extent desired.

It is thus seen that other modes generally of 40 applying the principle of the invention may be employed,provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point tinctly claim as my invention:-

1. A method of making vulcanized fiber, which comprises subjecting fibrous cellulose to a hydrating treatment, and eliminating internal mechanical cockling stresses by amorphizing stressoccasioning fibrous structure without destroying the gross contour, and setting the mass.

2. A method of making vulcanized fiber, hich comprises subjecting fibrous cellulose sheet material to a hydrating treatment, eliminating mout and dis- 45 ternal mechanical cockling stresses by substantially completely amorphizing the fibrous structure without destroying the gross contour, and setting the mass.

3. A method of making vulcanized fiber, which comprises subjecting fibrous cellulose sheet material to the action of a concentrated zinc chloride solution, supporting the sheet material while eliminating internal mechanical cockling strains by substantially completely amorphizing stressoccasioning fibrous structure, without destroying the gross contour, setting the amorphized mass, and eliminating the residual zinc chloride.

4. Vulcanized fiber having internal mechanical cockling strains allayed by amorphizatlon of fibrous structure without destroying the gross contour. I

5. Vulcanized fiber sheet having internal mechanical cockling strains allayed by substantially complete amorphization of individual fibers without destroyingthe gross contour JOHN K. ANTHONY.