US2298994A - Manufacture of papermaking fiber - Google Patents

Description

Oct. 13, 1942. s. D. wELLs MANUFAC'RE OF PAPER-MAKING FIBER Filed June 25, 1941 lNvENToR D. Weds ATTORNEYS.

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Patented Oct. 13, 1942 MANUFACTUBE 0F PAPERMAKING FIBER smiley D. weils, combined Locks, wie, assigner to The Institute of Paper Ghemistry, a corporation of Wisconsin Application June 25, 1941, Serial No. 399,615

` 2Claims. Myv invention relates to. .improvements in the manufacture of an improvedpaper-making ber from bast ber which is a constituent of various plants, for example flax, hemp, ramie, and nettle,

which plants may be included under the general designation ofy bast ber straw.

In the manufacture of. cigarette paper, banknote, currency and similar papers, it is recognized that ber such as linen. hemp, ramie etc., consisting of bast bers, impart essential properties which cannot be obtained from ber derived from seed such as cotton or ber derived from lignocellulose such as the various types of wood pulp. The supply of ragsmade from puried bast bers is decidedly limited and itis usually necessary to use certain proportions of bers, not of bast origin, in order to supply the demand for paper of the type mentioned with the amounts of linen. hemp and other rags that are available.

In time `of war, when communication with countries that produce and use linen is cut on'. the situation is acute. At the same time that this condition occurs quantities of ax straw, more than sulcient to supply all of the requirements of bast ber in paper manufacture, are destroyed annually in Minnesota and North I Dakota as a waste product from the production of ax seed. Eilorts to mechanically separate the bast bers from the remainder of the stem so as to produce a ber free from shive have not been successful, although countless thousands of dollars have been devoted to the problem during the past fty years.

According to prior practice in the manufacture of paper-making materials. it was supposed that any pulverizing treatment of a raw material would so shorten the ber that it would be unsuitable for the manufacture of ne papers. n

eighths of the' straw. is shattered into small pieces which can be readily separated from the ber by proper treatment and equipment.

After the bast berhas been separated from the shive part of the straw, it is preferably subjected to a cooking operation of the .usual character, for example a conventional lime boil, and the usual washing and bleaching steps characteristic of the paper-making procedure in the manufacture lof bank-note, currency and cigarette papers.

- Example In the drawing, the gure represents in diagrammatic form an apparatus which I have successfully used in producing bast ber by my improved process.

In extracting bast ber from ax straw, the straw, if desired, may be cut to convenient lengths by means of a. rag cutter or other suitable device. Although this, in certain instances,

, may not be necessary with certain types of straw,

the contrary, I have discovered that the most economical and most effective way of detaching bast ber from the shive of the straw is by subjecting the material to a percusslve treatment which almost approaches a pulverizing operation. I nd that such treatment, it is true, does be subjected to considerable pressure or percusf sion before they are severed, while at the same I have found it of some advantage in preparing the raw material for subsequent steps in the process.

The percusslve treatment to which the straw is then subjected is effected preferably in a rod mill such as is used for pulverizing ores. A rod mill sixteen feet in length, seven feet in diameter and lled about half full with rods averaging two inches in diameter, is eective for the purpose, when operated at a speed of about twelve and one-half revolutions per minute.

Such rod mills as I have seen employed have all been designed for operating upon wet material. Of course, it is understood that, in practicing my process, it is advantageous to have the straw as dry as possible so that it will be quite brittle and shatter freely into small particles when subjected to the percusslve treatment.

The raw straw is fed into one end of the rod mill, preferably by means of some force feeding arrangement such as a cylinder and piston or a screw feed of conventional type such as is used for feeding coal toa stoker or chair in a threshing machine. The delivery end or discharge end of the rod mill is formed by allowing an open space of about three-fourths of an inch in width between the outer revolving shell of the rod mill and the inner cone or center portion oi.' the same.

'I'he shattered or comminuted material discharged from the delivery end of the rod mill is conducted to a gravity type shaker screen of 'about 40 mesh which removes the smaller partitime the shive, which comprises about sevenclei of broken up shive. these Smaller Particles 4usually representing more than one-half of the as is employed in the manufacture of upholstery felt from cotton linters. 'Ihe picking and garnetting or carding operation towhich the material is subjected in this machine serves to card out the liber from the woody shive parts. These shive parts which are rejected by the garnetting machine are returned to the inlet end of the rod mill for further treatment. In this way, practically al1 of the bast rlber is recovered.

The bast fiber which results from the final carding operation contains an insignicant percentage of shive. This is shown by the fact that the waste shive separated in this way contains about 25.6% of pentosan; whereas, the bast ber which is the ilnal product from the carding operation contains only approximately 2.8% of pentosan.

I claim:

1. The method of making an improved papermaking ilber4 which consists in subjecting dry iiax straw to a percussive treatment so as to shatter the woody parts and thereby detach most of the bast nbers from the shive parts, and subsequently subjecting the material to a carding operation so as to separate the bast iiber from the shive parts, and mechanically separating'the larger particles or the shive from the smallerl particles of the shive. and then repeating the percussive and carding treatments in the case of the larger particles of shive so as to salvage the bast fibers not effectively detached from the shive parts during the rst percussive treatment.

2. The method of making an improved papermaking fiber ywhich consists in subjecting dry ilax straw to a percussive treatment so as to shatter the woody parts and thereby detach most of the bast nbers from the shive parts, then mechanically separating the smaller particles of the shive from the fiber and the larger particles of Athe shive, then subjecting the material to a carding operation so as to separate the bast ilber from the larger particles of the shive, and then repeating the percussive and carding treatments in the case of the said larger particles of shive so as to salvage the bast ilbers not eflectively detached from the shive parts during the first percussive treatment.

SIDNEY D. WELLS.

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