US1885352A - Process of treating wood pulp for nitration - Google Patents

Description

Patented Nov. 1, 1932 UNITED STATES ARTHUR HOUGH, or PASSAIC, JOHN ROY eera ;(as-maximums W LLIAM CLELAND LEONHARD, or rassnro, nnyv EnsEY rnocnss or TREATING woonrunrfron iv rnarron No Drawing.

Our invention relates to improvements in the manufacture of nitrated cellulose obtained from the nitration of wood pulp having a tion. The strength of the acid may be varied within considerable limits,'say up to but herein we cover the use of sulfuric acid 7 of below the concentration used for producing parchmentization, in order that if desirable the acid-treated material, if in the form of pulp, may subsequently be formed into av sheet by any of the conventional methods or otherwise.

To carry out the invention the wood pulp as such or cellulose as such, in a suitably comminuted condition is subjected to the action of dilute sulfuric acid which may be about 10% H SO and then washed substantially free of acid, and dried to the required extent. The material may then be nitrated in the form of substantially segregated fibres or may be converted into a sheet (most advantageously before the drying step) and subsequently comminuted to an extent most. adapted to the selected method of nitrating. The whole treatment is best eflected at about ordinary room temperature, since it is well known that at elevated temperatures the cellulose would be partly dextrinized, or converted into a somewhat gum-like material. I

For eflecting the nitration, if it is desired to produce nitrocellulose of about 11% nitrogen content, we may employ an acid mixture of say 60% sulphuric acid, 21% nitric acid and 19% water, (these acids being figured on the basis of 100% purity). This temperature of the mixed acids during nitration should be at about C. This produces a nitrated cellulose which is particularly suitable for Application filed January 29,'193o;s=iia1 ira-424,440;' I

us'ein making nitrocellulose plastics ofhigh solubility:

An important difference between nitratedv waterleaf made from alpha pulp, previously treated with sulphuric acid asldescribefd, and that made from the untreated .waterle'af, is the color. of the two-products. If. nitrated waterleafr(previously treated with the acid) bedried and dissolved in-any suitable solvent such as ether-alcohol or acetone and then a.

film made from it, say, by pouring the fluid on a glass plate-and allowing the solvent to evaporate, the-.resulting film is clear andalmost water white.

If however, nitrated waterleaf made from this pulp, not previously treated with acid,

be dissolved in the solvent as in the other case, and a film prepared from it, then the resulting film will be yellowish, at any rate it will be distinctly diiferent,and can readily be distinguished from the other.

'We claim V 1. The process of making a nitrated prodnot which comprises subjecting wood pulp to the action of sulfuric acid of a strength below that which produces dextrination or parchmentization of the cellulosic material, washing the product substantially free of acid, drying, and thereafter nitrating same.

2. A nitrated product resulting from the treatment of disaggregated wood pulp with sulfuric acid, such acid of a strength below that required for parchmentization or dex trination, and subsequently nitrating.

3. In the nitration of alpha wood pulp, the herein described preliminary treatment of said material, by soaking the same in a sulfuric acid of a concentration too low toe'fiect parchmentization of the said material, then washing out the acid, whereby said material is rendered especially suitable for nitration and nitrating the product.

' 4. In the nitration of wood pulp consisting 5. In the nitration of Wood pulp consisting largely of cellulose, the herein described preliminary treatment of said pulp which comprises soaking the pulp in comminuted condition in sulphuric acid of about to about, 391%, Washing out, the acid. and sheeting the. treated pulp and nitratingr the same.

6 In the nitration of Wood pulp consisting largely of cellulose, the hereinv described pre-' liminary treatment of said pulp which comprises soaking the pulp; in comininuted con; dition in sulfuric acid "of about 10%, Washing out the acid and shefifiing; the; treated pulp and nitrating the same.

'Z. The process oimakinga; nitratedi prod-l uct which comprises subjecting Woodjpulpito thev action of sulfuric acid of about 5% to about 30% strength, washing the productsubstantially free of acidg drying, and; there-v aften nitrating same.

8'; A nitratecl' product resulting from the treatment of disaggregated WOOdi pulp with sulfuric acid:,such: acid of about 5%xto about strength, and subsequently nitrating.

ARTHUR; HOUGH.

JOHN RQLYJ DUFFOZRDL WILLIAM CLELANSD; LEONHARD;