US1279328A - Manufacture and production of cellulose compounds. - Google Patents

Description

weiijrjnn HAMIS GLOVER, or BRAINTREE, AND LEONARD PHILIPYWILSON, or:

COVENTRY, ENGLAND, AssIeNoRs; BY MESNE- ASSIGNMENTS, TO THE VISCOSE COMPANY, OF MARCUS HOOK, PENN SYLVANIA.

SYLVANIA, A CORPORATION-QF PENN- UFACTUREAND PRODUCTION OF CELLULOSECOMPOUNDS.

No Drawing.

To all whom it may concern:

Be it known that we, WALTER HAMIS GLOVER, a subject of the King of Great Britain, residing at The Avenue, Braintree, in the county of Essex, England, and LEONARD PHILIP WILSON, a subject of the King of Great Britain, residing at Rosemont, Holyhead Road, Coventry, in the county of Warwick, England, have invented new and useful Improvements in the Manufacture'and Production of Cellulose Gompounds, of which the following is a specification. y

In the manufacture of viscose, or solutions of sodium cellulose xanthate, alkali cellulose is first made by steeping cellulose in a solution of caustic soda of about 1.2 specific gravity. The surplus soda solution is then removed and the mass of alkali cellulose is disintegrated and, as a rule, packed in boxes, to mature or mercerize. The period .of maturing, or mercerizing, and the temperature at which it takes place (generally between 15 and 25 centigrade) determine the viscosity of the viscose and must be varied with the different qualities of cellulose used.

It has hitherto been supposed that the I changes which take place are due to a slow direct action of t-he'alk-ali upon the cellulose, that air has a prejudicial effect upon the reaction, and that a lowrtemperature is requisite for storage and for obtaining satisfactory results, and the methods hitherto adopted in manufacture have been based upon these sifppositions. See, for example, Margosches in Die Viscose, Leipzig,'1906, pages 41 and 42. i

Alkali-cellulose has been packed in tightly closed vessels, containing preferably not more than 100 kilos, in order to prevent the entrance of air and any spontaneous heat- .ing due to the exothermic nature of the reaction. The maturing process has generally occupied several days.

It has now been found that oxidation is an action essential to the changes which take place during theprocess of maturing, and that while, for instance, the required eifect is not produced if cellulose (for example wood-pulp) be completely immresed in the caustic sodasolution for several days- (a period which would be sufficient if, after a short immersion, the alkali cellulose were 'Application filed January 22, 1915. Serial No.- 3,$30.

Specification of Letters Patent. -Pa,tentad. Sept. 1'3, 1918c I exposed to the action of-air in a more, or

less, combined space) on the other hand, treatment with caustic Soda solution for a comparatively short time, say for about from four, tofive, hours, is suflicient to complete the desired action if oxygen, or other suitable oxidizing agent be supplied, and this invention consists in'sup plying an oxidizing agent which may be effected in any suitable way; for example, we may use a soluble peroxid, such as sodium peroxid, or hydrogen peroxid, or a mixture of such peroxide, or a hypochlorite, or a current of oxygen, or inert gas, or gases, mixed with oxygen, or air may .be used.

The following are examples of how this invention, having for its basis the treatment of alkali-cellulose with oxygen, or other suitable oxidizing agent, may be performed, but it is not limited to these examples.

Ewa/mple 1.

2 kilos of sodium peroxid are dissolved in 200 kilos of 17% per cent. solution of caustic soda and 5 kilos of wood-pulp, in sheet form, are immersed in the liquid at a temperature of about 18 centigrade, for from four, to five, hours. The product is then removed and pressed until it weighs about 15 kilos,

usually adopted in the manufacture of viscose, is placed in a vessel, which is rotated and, by means of a water-jacket, kept at a temperature of 410 Centigrade. After a short time, when the contents have acquired the same, or about the same, temperature as that of the vessel, a steady current of air is blown through the contents for four hours. Cold water is then run through the jacket to cool the contents, and, when they have been reduced to a temperature suitable for xanthation, carbon bisulfid may be added and the conversion into viscose completed.

As stated, we do not limit ourselves to the particular ways described in these examples, for effecting the oxidation of alkali cellulose according to this invention as it may be effected in other ways. For example, we

"may blow oxygen, or air, or a mixture of oxygen with air,

we do not claim the or with inert gas, or gases, through the solution in which the-cellulose is immersed, or through the heated alkalicellulose, or we may expose large surfaces of the alkali-cellulose freely to the atmosphere in a room heated above centigrade, but limited exposure of alkali-cellulose to the action of atmospheric air at temperatures of 30 Centigrade and under, such as occurs in the maturing of alkali-cellulose in the usual manner.

When using oxidizing agents other than those hereinbefore named regard must be had to the question of the possibility of secondary changes, or the formation of sec ondary products, which, by reason of their color, insolubihty, tendency to promote fur ther changes, orotherwise, might, for the purpose in view, be objectionable. For example, if a solution of potassium permanganate (whichis a suitable oxidizing agent in certain cases) beused, the insoluble brown hydroxid of manganese is formed and therefore potassium permanganate should not be used in cases where such hydroxid would p be objectionable.

By means of this invention-the time required to mature alkali-cellulose can be greatly reduced, for example to a few hours,

1 while the process is brought more under control, and kinds of cellulose which were previously considered as unsuitable can be successfully used.

Although we have described'this invention more particularly with reference to'the manufacture of viscose solutions, it. is not limitedthereto but includes the oxidation of alkali-cellulose as hereinbefore explained whetherin the manufacture of viscose, or not.

IBy'varying the time,

p or the temperature, of treatment, or the quantity of oxidizing agent employed, products of different 'degrees of oxidation, and viscose solutions of various degrees of viscosity, and other qualities, can be obtained. The invention is emi- I I nently useful in the manufacture of artificial silk, but it is to be understood that the products can be used for any purpose for which they are applicable.

It is to be understood that in the present specification and claims the term alkalicellulose is used inits technical sense and should not be confused with the well known soda-pulp. The basis of the invention is the discovery that cellulose when chemically combined with caustic soda in the form of what is known technically cellulose by acting upon pounds,

as alkali-cellu- A tar/awe lose is particularly sensitive to oxidation and that a useful product can be so obtained. A typical alkali-cellulose is prepared by steeping cellulose in a solution of 17.5 per cent. caustic soda and pressing to about three times its original weight; so that it p (15) percent. caustic contains about fifteen v soda and twenty-eight (28) per cent. cellulose. It is decomposed by the action of water into caustic Soda solution and cellulose.

If a weak solution of about five (5) per.

cent. caustic soda be used to soak the cellulose and it is well pressed to remove surplus moisture, the cellulose doesnot combine appreciably with the alkaliiand the product is found to containvonly from. 2 to 3 per cent. caustic soda. f

Alkali-cellulose is quite distinct from soda-pulp which contains no .alkali and which has had the soda washed out after being boiled in it. To such a product as soda-pulp the invention and the subjoinecl, 7

claims do not relate.

What We claim is a 1. In the manufacture of cellulose compounds, subjecting'alkali-cellulose to oxidationby positively supplying thereto an oxidizing agent.

2. In the manufacture of cellulose compounds, subjecting alkali-cellulose to oxidation by positively supplying oxygen thereto.

3. In the manufacture of cellulose compounds, efiecting' the oxidation of alkalicellulose by posltively passing oxygen'in adtion of suiiicient strength to form alka li cellulose and an oxidizing agent.

7. The manufacture of viscose which consists in treating alkali-cellulose with an oxidizing agent and converting the product into cellulose xanthate.

. r In testimony whereof we have signed our treating wood-pulp. withcaustic 'soda' solu- Y names to this specification in the presence subscribing witnesses. WALTER HAMIS GLOVER. I LEONARD PHILIP WILSON. Witnesses: 1

ERNEST HARKER, STELLA BENSON.

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