US1429427A - Parchment paper or vulcanized fiber and process for making same - Google Patents

Description

Patented Sept. 19, 1922.

UNITED STATES PATENT, OFFICE.

BERNARD HERSTEIN, OF BROOKLYN, NEW YORK.

rancnmanr PAPER on 'VULCANIZED FIBER ANDPROCESS nonmaxme SAME.

.No Drawing. Reflled for abandoned application Serial No. 183,728, filed July 31, 1917. This application filed April 6, 1920.

To all whom it may concern:

Be it known that I, BERNARD HERSTE-IN, a citizen of the United States, residing at Brooklyn, in the county of Kings, city and State of New York, have invented an Improved Parchment Paper or Vulcanized Fiber and Process for Making. Same, of which the following is a specification.

Parchment paper or vulcanized fiber as now known in the arts is made by treating paper either with sulphuric acid of appropriate strength or with a solution of zinc chloride. It has also been proposed to treat paper with nitric acid but inasmuch as in this treatment the cellulose molecule disintegrates rapidly, it has never been commerically possible to make fibre of any thickness because the acid cannot be removed.

quickly enough to prevent degradation of the paper. Even where alkalis have been applied to these nitric acid treated papers to neutralize the acid, this neutralization was the only effect produced and the alkali has no such action or result as it has in the process devised by'me as hereinafter described.

I have found that by careful manipulation paper may be treated with an acid mixture containing approximately the proportionsof 63% sulphuric acid, 10% nitric acid and 27% water at a low temperature in such a manner that while the individual cellulose particles will plasticize and flow together yet the original form and sha e of the paper will be retained dimensiona ly and after the acid has been removed therefrom by washing with water will yield a new and peculiar kind of so called parchment paper with technical and commercial advantages not possessed by parchment paper or vulcanized fiber made by any other method. Of'these advantages the most characteristic is its faculty of reverting again readily to aplastic condition when in contact with even diluted solutions of caustic alkali such as caustic soda.

Chemically this new parchment paper, if for the purpose of illustration' a term well known in the arts may be applied to a new .product, is characterized by the fact that it contains a small percentage of nitro en as part of its elementary composition. y pro: ductis in reality a cellulose derivative of very low nitration, and tothe presence of just that small percentage of nitrogen are due the specific qualities claimed for it, while owing to its very low state of nitrawater.

.into a derivative thereof Serial N0. 371,710.

tion it is utterly harmless both in use and manufacture.

In proceeding according to my invention 1' first pass the paper in sheets or rolls through an acid mixture containing about 63% by weight of sulphuric acid about 10% of nitric acid the remaining 27% being This mixture I obtain most conveniently by mixing 85 parts of commercial sulphuric acid of 1.66 specific gravit with 15 parts of commercial nitric acid of about 1.42 specific gravity. The acid mixture is kept at a low temperature preferably not higher than 20 C. The paper remains in contact with the acid for a short interval until it loses in part or wholly its opacity and the individual cellulose particles coalesce to a more or less transparent sheet which is then atonce washed repeatedly with water to remove all acid from it and thereby becomes again opaque. The paper during this process has retained its original dimensions but the chemical reaction which has taken place has changed the cellulose 0 containing apercentage of nitrogen materially lower even than tl1e 6.77% required for the theoretical mononitro cellulose. ormer investigations have shown that the derivative obtained by my process did not contain more than 45% of nitrogen and often considerably less.

In the quantitative composition of the acid mixture used as given above, I have stated what I conceive to be the most advantageous ratio of components, although the propertion may be varied within certain limits. The absolutely essentialpart of my invention consists in treating the paper in such a manner with a mixture 'of acids nameldethat the individual cellulose tinize more or less comp tely and be transformed into a low derivative of cellulose, while the paper as a whole will retain its ]particles will gela-' original .form and dimensions and, after being freed of acidity by washing with water, will regelatinize when in contact with cold solutions of caustic alkali such as caustic soda. This being the main object, the particular ratio between the uantities of sulphuric acid, nitric acid an water may be left to the selection of the "manufacturer.

The product obtained by treating paper according to the process described above can, after drying, be used directly for various technical purposes or it may, while yet Wet, be passed through a cold solution of caustic soda or similar alkali the strength of which is adjusted according to the moisture contents of the paper. It will thereby again regelatinize and become plastic in which form many layers can be cemented together to any desired thickness, and from which the alkali is readily removed by washing with Water. 1

What I claim is: a I

1. The process of making an improved parchment paper or vulcanized fiber which consists in treating paper with a mixture containing approximately 63% of sulphuric acid, 10% of nitric acid and 27% of water at a low temperature for a short time and as soon as the individual cellulose particles have become gelatinized, withdrawing the paper from the acid mixture, then removing the acid contained in the paper all before the original dimensions of the paper are destroyed and then gelatinizing the paper by treatment with an alkali solution and bringing together layers of the material so treated to cause them to unite.

2. The process of making an improved parchment paper or vulcanized fiber which consists in treating pa er with a mixture containing approximate y 63% of sulphuric acid, 10% of nitric acid and 27% of water at a low temperature for a short time and as soon as the individual cellulose particles have become gelatinized, withdrawing the paper from the acid mixture, then Washing out the acid from the paper all before the original dimensions of the paper are destroyed and then regelatinizing by means of a cold solution of caustic alkali and bringing together layers of the material so treated to cause them to unite.

3. The process of making an improved containing approximately 63% of sulphuric acid, 10% of nitric acid and 27% of water at a low temperature for a short time and as soon as the individual cellulose particles have become gelantinized, withdrawing the paper from the acid mixture, then removing the acid contained in the paper all before the original dimensions of the paper are destroyed, then gelatinizing the paper by treatment with an alkali solution, bringing a number of layers together to the required thickness and causing them to cohere by reason of their regelatinized condition and then washing out the alkali.

4;. The process of making an improved parchment paper or vulcanized fibre which consists in subjecting the paper to atreatment comprising two distinct stages of operation upon the paper While in layer form, one for weakl nitrating the fibre and another for rege atinizing the fibre, and then bringing several layers of the so treated paper into adhering contact.

5. A new article of manufacture being an improved parchment or vulcanized paper consisting of layers of papers the cellulose particles of which are nitrated so as to contain not in excess of 4c%% of nitrogen and cemented together by an alkali induced gelatinization of said weakly nitrated celluloseof the paper layers.

' 6. A new article of manufacture being an improved parchment or vulcanized paper consisting of one or more layers of paper, the cellulose particles of which have been nitrated so as to contain not in excess of 43 of nitrogen, said paper layers being adapted to be cemented together by an alkali induced gelatinization of said weakly nitrated cellulose of the paper layers.

lln testimony whereof I have hereunto set BERNARD HERSTEIN.

. my hand.