US1781668A - Fibrous sheet material and process of making same - Google Patents

Description

Patented Nov. 11, 1930 UNITED STA res PATENT OFFICE JAMES C. PEABODY, BOSTON, AND ALFRED BROWN, OF EVERETT, MASSACHUSETTS; E. LOUISE PEABODY, EXECUTBIX OF SAID JAMES C. PEABODY, DECEASED, ASSIGN- ORS, BY DIRECT AND MESNE ASSIGNMENTS, TO FRANK B. HOPEWELL, OF NEWTON,

MASSACHUSETTS, AS TRUSTEE FIBROUS SHEET MATERIAL AND PROCESS OI! MAKING SAME No Drawing. I Application filed July 23,

This invention relates to the art of making fibrous sheet material of a paper-like nature and to the-resulting product.

" The object of the invention is to produce by treating natural vegetable cellulose fibres, such as those of hemp, ramie, cotton andwood, a paper-like sheet material suitable for a large variety of purposes where strength is required such as material for innersoles and reinforcements for shoes, such as a base for artificial leather and which is capable of being molded into a wide variety of forms and which, after it has once been dried, will not disintegrate when immersed in water.

The object of the inventiori is further to produce such a material'which shall be and remain flexible and soft.

The object of the invention is further and more particularly to produce rapidly and economically a paper-like material from wood pulp fibre having the foregoing characteristics.

These and other objects and features of the invention will a pearmore fully from 2 the accompanying. escription and will be particularly pointed out in the claims.

The important feature of this invention resides in the chemical treatment of natural cellulose vegetable fibres to bring them into a swollen gelatinous state insoluble in water or dilute caustic soda. Such treated fibres are then used, preferably mixed with untreated fibres, in the manufacture of paper or sheet material by processes of a type usually employed in the manufacture of ordinary paper.

The natural vegetable cellulose fibres may be obtained from a variety of materials such as hemp, ramie, cotton and wood pulp. But the invention is particularly useful in connection with wood pulp and that fibre is em ployed in disclosing the preferred form of 1929. Serial No. 380,456.

pressed to about three times the weight of I the' original cellulose fibre. The soda cellulose thus formed is allowed to age for about three days. The soda cellulose is then treated for about four or five hours with carbon disulphide in amount about equal to half the weight of the original cellulose fibre to form what is .known as cellulose xanthate. Cellulose Xanthate is completely soluble in water or dilute caustic soda from which it may be regenerated in the form of rayons, films, etc.

The present invention depends upon the discovery that by properly correlating (1) the proportion of the alkali such as caustic soda, (2) the proportion of carbon disulphide, (3) the time of treatment with carbon disulphide, and (4) the temperature at which the reaction is carried on, an incomplete conversion of the fibres into cellulose xanthate. may be effected so as to leave the fibres in a swollen gelatinous state, and characterized by being insoluble in water or dilute caustic soda; Either or all of these factors may be varied within limits to produce the desired results. The reduction in the proportions of the alkali and of the carbon disulphide in the solution below those commonly employed in the viscose process, the reduction'in the length of time of the treatment particularly with carbon disulphide, and decrease in the temperature at which the reaction is carried on all tend to produce the desired result of incomplete conversion of the fibres into cellulose xanthate. Consequently, by varying one, any or all of these factors in accordance with this principle, a correlation thereof. may be effected to secuie the desired result.

For example, the following process has .been found satisfactory. A given weight of dry wood pulp fibre is treated for one hour with a 10% solution of caustic soda at room temperature or substantially 60 F. to 90 F. The stock is then whizzed in a centrifuge or pressed in a hydraulic press to reduce it to about three times the weight of .the original fibre. Carbon disulphide, equal in weight to about one-quarter of the weight of the original fibre, is then added to the stock in amplei a suitable container and the mixture agitated for several minutes and then allowed to stand for about one hour. This is found to effect an incomplete conversion of the fibres into cellulose xanthate and to leave the fibres in a swollen gelatinous state and insoluble in water or dilute caustic soda. It Will be observed that, in this correlation of the various factors, the time of the reaction and the proportions of the alkali and of the carbon disulphide have been materially reduced below those referred to as employed in the ordinary viscose process, while the temperature of the reaction is retained at normal room temperature.

Again it has been found that the proportions of the alkali in the solution, as, for ex- 17 of caustic soda and carbon disulp iide equal to one-half the weight of the-fibre may be retained as in the viscose process and the desired results secured by substantial reduction in the length of time of the treatment as from the five hours commonly employed to one-half hour at room temperature. Again if the proportion of carbon disulphide be materially reduced, this will besuflicient, the other factors remaining substantially the same as in the viscose process. Again it has been found that the time of the reaction may be increased if the proportion of carbon disulphide employed has been materially reduced. For example, if one-fourth of the weight of carbon'disulphide employed in the viscose process be used, the length of time of the reaction may be slightly increased.

The various factors may therefore be varied so long as they are all brought into such a correlation as to effect an incomplete co nversion of the fibres into cellulose xanthate and leave the fibres in a swollen gelatinous state and insoluble in water or dilute caustic soda, characteristics which are readily ascertainable by inspection and the simple test as to insolubility.

The fibres resulting from the foregoing treatment in accordance with the principle of this invention may then be employed for the manufacture of paper according to the usual processes, as, for example, by first being mixed with water in a beater 0r rod mill to form the stock and, second, by reducing this stock to sheet form as through the operation of a Fourdrinier machine.

It will be found that the time required toproduce the stock in the beater or rod mill is very much less than when the stock is made from untreated fibres and, further, it will be found that the stock produced from the treated fibre of this invention is much more free than untreated fibre, that is, the water drains faster from the treated fibre when it is run over the Fourdrinier machine.

But the best results are secured and at less expense by mixing the treated fibre of this invention with untreated fibre in the beater or rod mill to form the stock and preferably in about equal proportions. But in either event, it will be found that a much less time is required to produce the stock with the treated fibre in a heater or rod mill.

The sheet material or paper has marked advantages and characteristics. It is of great strength and toughness and this strength may be considerably increased by prolonging the beating action in the formation of the stock in the beater or rod mill.

The material does not disintegrate, after it has once been dried, when immersed or soaked in water and even then retains considerable strength.

The material is suitable for many purposes, includin inner soles and reinforcements for shoes, aliase to receive the various coatings employed in the manufacture of artificial leather, and those purposes to which a wide variety of woven and fibrous sheet materials have heretofore been employed. The material is readily moldable before it is dried or when moistened into various shapes and forms.

While caustic soda is preferably employed, it will be understood that, with suitable variations familiar to those skilled in the art, caustic potash may be employed.

The material, either during the process of the mixing of the stock or its formation in sheet form or afterward, may be treated with various substances to produce particular desired results. One desired result which may thus be produced is to make the sheet material more flexible by the addition of glycerin or a similar substance. For this purpose glycerin may be either added in the beater in the mixing of the stock or the finished sheet material may be soaked in a glycerin solution. The main characteristic of glycerin which secures the desired result is that it is hygroscopic and acts to retain sufficient moisture in the paper to render it soft and flexible, although glycerin itself has some softening effect. Any suitable hygroscopic softening agent may therefore be employed in lieu ofglycerin for this purpose. A 5% solution of glycerin is found desirable when the paper is soaked therein.

From the foregoing disclosure of the prin ciples of this invention and specific applications of these principles, one may readily treat natural vegetable cellulose fibres to bring them to a swollen gelatinous state insoluble in water or dilute caustic soda and make therefrom, either alone or mixed with untreated fibre; a sheet or paper-like material having the desired characteristics.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. The process of treating natural vegetable cellulose fibres which consists in treating the fibres with caustic soda and carbon disulphide and water after the manner of cellulose xanthate, as to effect only an incom- K the viscose process, but with the Proportions of said reagents to the water so reduced, beyond those normally employed at the prevailing temperature to convert the fibres into caustic soda.

3. The process which consists in treating natural vegetable cellulose fibres with caustic soda, carbon disulphide and water to produce an incompleted cellulose xanthate condition and to leave the fibres swollen and gelatinous and insoluble in water or dilute caustic soda.

4. The process of treating natural vegetable cellulose fibres which consists in incompletely converting the fibres into cellulose xanthate to render the fibres swollen, gelatinous and insoluble in water or dilute caustic soda. K

5. The rocess of making a fibrous sheet material f i'om wood pulp which consists in treating a quantity of substantially dry wood pulp with a 10% solution of caustic soda for one hour at a temperature of from to 90 F., in mechanically removing the liquid in the stock so produced to reduce the stock to a weight about three times that of the original quantity of wood pulp, in adding to the stock carbon disul hide of a weight of about one-fourth that o? the original quantity of wood pulp, inagitating the stock for several minutes, in allowing the stock to stand for about an hour, in mixing the stock with an equal quantity of ordinary Wood pulp stock, and in beating the mixture thoroughly and forming into sheet form by methods usually employed in paper making.

6. The process of making fibrous sheet material which consists in treating wood pulp according to the process defined in claim 1, in then mixing the stock with ordinary wood pulp stock, and in beating the mixture thoroughly and forming the same into sheet material by methods usually employed in paper' making.

'7. The process of making fibrous sheet material which consists in treating wood pulp terial by methods usually employed in paper making.

8. The process of making fibrous sheet material which consists in incompletely con-- verting natural vegetable cellulose fibres into cellulose xanthate to render the fibres swollen, gelatinous and insoluble inivat'er or dilute caustic soda, in mixing therewith untreated natural vegetable cellulose fibres in water to form a stock, in beating the stock thoroughly and forming into sheet form by methods usually employed in paper making.

9. The process of making fibrous sheet material which consists in treating wood pulp according to the process defined in claim 1, in then mixing the stock with ordinary wood pulp stock, in beating the mixture thoroughly and forming the same into sheet material by methods usually employed in paper making,

and in soaking the sheet material in a solution of a suitable hygroscopic softening agent to render the material soft and flexible.

10. The process of making fibrous sheet material which consists in treating wood pulp according to the process defined in claim 1, in then mixing the stock with ordinary wood pulp stock, in beating the mixture thoroughly and forming the same into sheet material by methods usually employed in paper making, and in soaking the sheet material in a 5% solution of glycerin to render the material soft and fiexibl'e.

. 11. The process of making fibrous sheet material which consists in incompletely convex-ting natural vegetable cellulose fibres into cellulose xanthate to render the fibres swoling the same into sheet material by methods usually employed in paper manufacture.

13. The process of making fibrous sheet material which consists in incompletely converting natural vegetable cellulose fibres into cellulose xanthate to render the fibres swollen. gelatinous and insoluble in water or dilute caustic soda, in forming the same into a stock, in beating the stock thoroughly and forming into sheet form by methods usually employed in paper making.

14. A swollen, gelatinous vegetable fibre incompletely converted into cellulose xanthate and insoluble in water or dilute caustic soda.

15. A sheet of fibrous material composed of natural vegetable fibres mixed with swollen, gelatinous vegetable fibres incompletely converted into cel ulose xanthate and insoluble in water or dilute caustic soda.

16. A sheet of paper-like material com posed of natural wood fibres and wood fibres previously treated to present'a swollen, elatinous condition insoluble in water or di ute caustic soda.

17. A sheet of fibrous material comprising swollen, gelatinous vegetable fibres incompletely converted into cellulose xanthate and insoluble in Water or dilute caustic soda.

18. A sheet of fibrous material composed of natural vegetable fibres mixed with swollen, gelatinous vegetable fibres incompletely converted into cellulose xanthate and insolu ble in water or dilute caustic soda and containing glycerin to render the sheet soft and flexible.

19. A sheet of pa er-like material composed of natural woo fibres and wood fibres previously treated to present a swollen, gelatinous condition insoluble in water or dilute n caustic soda and containin glycerin to render the sheet soft and flexi le.

20. A sheet of fibrous material comprising swollen, gelatinous vegetable fibres incompletely converted into cellulose xanthate and an insoluble in water or dilute caustic soda and containing glycerin to render the sheet soft and flexible.

In testimony whereof, we have signed our names to this specification. .i- JAMES C. PEABODY.

ALFRED BROWN.