US1693573A - Cellulose peoduct and method ixjepsoduootgr such product - Google Patents

Description

Nov, 27, 1928.

W. W. CARTER CELLULOSE PRODUCT AND METHOD FOR PRODUCING SUCH PRODUCT Filed Dec. 27, 1922 lnvewior: V @Zviwm wearifer M maawvm flij 8 Patented Nov. 27, 1928.

UNITED S ATS? WILLIAM w. CARTER, or nnnnnmvr,trassacsosnrrs, ASSIGNOR, or ouE-nALn'ro HENRY r; NELSON, or Bos'roit, "MASSACHUSETTS.

cnLLULosE 'rnonnorann METHOD non rsonnorns soon PRODUCT.

llpplication filed December 27, 1922. ScrialYNo. 609,297. I

This invention pertains to improvements in products of and methods for treating fibrous stock and an apparatus for use in connection with such products and methods. More particularly, though not exclusively, the invention relates to steps in the manufactire of waterproof paper rendered tough by a binder including fibres toughened by the tliiocarbonv ate or Xanthatereaction.

In the drawings, which show a preferred J form of one embodiment of an apparatus in which my preferred method may be carried out: y V

Figurel shows a side elevation of a crate adapted to contain the fibrous stock during chemical reaction various elements Fig. 2 is a section on the 1, showing the crate with sheets of paper stock enclosed therein and ready for immersion in the treating bath; and

Fig. 3 is ajsecti-onof the crate and contents on the line 3+3 of Fig. 2 after treatment in and physical admixture of the chemical bath and illustrating the limitation of the swelling of the contained fibre.

stock.

Waterproof from paper stock and gum, such, for instance, as resin size. It is among the purposes of the present invention greatly to increase the strength of such waterproof papers. It is way fortified against the absorption of water,

a mere coating of sizeon the outside of fibres so treated ise'xceedingly susceptible to the action of Water because, if there is the slightest break in the waterproof coating of the p fibre, the water will penetrate, cause the fibre to swell, break the waterproof gum coating and lose all protection.

It has previously been practised to treat paper stock successively with alkaline gum emulsions and cellulose Xanthate to provide a binder stock which is later mixed in the beater line .22 of Fig.

papers are ordinarily made with thema-in body-of paperfstock and the gum emulsions. lVhile the product provided eater .oFr c a", g I

by this method is to soine extent waterproof and very tough, it is not entirely waterproof because the stock forming the binder. and which has been subjected to the Xantliate reaction is very absorbent, in, fact, being more absorbent than the original unsized fibre. V 1

I have found that very satisfactory results are obtained by providing a binder of, fibres which are permeated with'awaterproof size and also more orless Xan'thated." The-size V cannotbe satisfactorily introduced after thev i-zanthate reaction, and Iliave, therefore, in

the present application described a method in whichthe introduction of the sizeis abcomplished at the same time asthe elfecting ofxanthate reaction is'eifected or, in any case, prior tocompleti'on of the Xanthate reaction. Thus, where V the, initial portion of the xanthate reaction comprises dipping the binder stockin an alkaline such as sodium hydroxide, I prefer to combine with the sodium hydroxide,of say 15% solution, a gumemulsion of any of the well-known paper sizes:

Thus, the gum is carried to the interior of the fibre before the exterior thereof is Xanthated and thereby rendered a colloid which willarepe l or inhibit difi usion of the colloid gum.

The subsequent completion of the Kant-hate reaction with carbon disulphide does not affect the'gum wit-hin the fibre and it is not until the binder stoclnmix-ed .witl the paper stock and shccted, is dried or fed between the calencomes a waterpro'olhig agent. a

I have found that while Xanthated 'fibres darsor pressesthat the gumis fused fandbe- I may be rendered exceedingly,tough by completing the xanthate reaction, andwhile they, may be rendered exceedingly absorbent by the Xanthate reaction, the Xantliatedfibre when in such condition as to be adherent is ordinarily readily dissolved in water and therefore to. an exceedingly large extent.

Washed away and lost in the paper machine.

Thesolubility of the Xantha ted fibre is to y a large extent dependent on the amount of absorption during treatment w th sodium hydroxide. as the initial step in the. Xanthate method The more sodium hydroxide that,

isabsorbed and combined during this opera tion, the greater isthe absorptive property of the stock if later subjected to-water. It

has been heretofore attempted to, limit the.

amount of sodium hydroxide in the fibres by pressing the fibres after they have been immersed in the sodium hydroxide or equivalent treating agent. It has also been attempted tolimit this absorption by only supplying to the fibre the desired amount of the sodium hydroxide. The first of the above-described prior methods, while satisfactory for artificial silks, has proved unsatisfactory for paper-making processes because the entire structure of each fibre is effected. by the sodium hydroxide and the whole fibre is therefore soluble in water when the Xantl'r te reaction is completed. The second of the above-dose ibec methods is unsatisfactory because it is a Jhysical impossibility, regardless of the extent of kneading, measuration o mixing effected, to distribute evenly the fi among the mass of fibre stock. Those portions of the fibre stock which first receive the liquid become saturated, while the remainder are instnnciently treated even as to their surface,

I I have found that where 1 limit the action of the chemical on the fibrous stock by confining the stock so as to limit the swelling thereof during the chemical reaction of the sodium hydroxide, that the surface of each of the fibres is to the desired extent acted upon by the sodium hydroxide and therefore conditionedto complete the Xanthatea reaction when immersed "in the carbon disulphide. On the other hand, the interior of each fibre has not been enabled to swell to any considerable eXtentand for this reason has not permitted entrance therein of the treating fluid and is'not in condition fully or even partially in some instances to be affected by the reaction when immersed in the carbon disulphide. While some of the treating fluid reaches the centre of a fibre, theallraline content of the .fiuid reaching the centre 1s so reduced, by

combination with the exterior portions of the fibre through which it has passed, as to minimize any reaction such fluid is, however, such as to maintain the gum emulsion. The paper stock may, if desired, be confined in a container adapted to limit swelling in one dimension only, as by exerting pressure on the tp and bottom only, the crate or container being without sides. I prefer, however, to limit swelling in all directions. Where each fibre provides in its interior anon-Xant-hated or partially Xanthated core, the chemical bond of the xanthated surface of the fibre for the core is sogreat as to overcome the tendency, which would otherwise exist, for the Xanthated portions of the fibre to be dissolved in the water.

In practising the specific ei'i'ibodii'nent of my invention selected for illustrative purposes, I take ordinary paper stock, which may be in sheet or board form, and place any desired number of sheets or boards in a crate.

Referring to; Fig. 1, the crate, formed of perforated metal, is provided with a removable top '7 and a hinged front 8, the ends, bott m and back preferably fixed and the ends provided with trunnions 9 to be engaged by suitable tongs on a crane or hoist. In loading, about four inches of the sheets or boards are first placed on the bottom, a separator 11 then. introduced, another four inches of stock above this and so on until the crate is filled, when the side 8 is swung up and the top 7 is screwed down by suitable damn ng devices. The sep. ..ors 11 are 'cfcrably corrugated and perto in the funcion of permitting the liquid readily and ily to flow to the inner portion of the lhe fibre stocl: in sheet or board form is loosely pressed that capillary action of the liquid causes entrance thereof to the cente of the four inch layers of sheetsor boards very quickly. When the pulp sheets and separators are all in position and the crate closed.

but one-having electrical insuiatmg propertie I may utilize an emulsion of artificial gums or resins suitable for dielectrics. For purposes of this appiication, however, all products of sheet, molded or other form containing cellulose fibres may be considered a paper. 7

The sizes when in the emulsion are very finely divided particles having little if any adhesive properties. They are, however, so small as to permeate within the structure of the individual fibres of the stock.

The crate of paper stock may be left in the bath of sodium hydroxide-solution until it has swelled sutficientiy completely to fill and to exert some pressure on the crate. This expansion may preferably be such to provide ninety cubic inches of swelled celi the sheet; then be removed, its top and bot-tom released and its contents permitted to age until the reaction is complete. The reaction will be complete in about twelve hours under nor,- mal conditions, and may continue for a longer period so long as the stoc c. es not dry out and so long as carbon dio'; e of the air dt not combine with the sodium and prevent proper reaction therewith of the carbon di K sulphide. \Vhen using is connilete the reaction may be co" i ng the stock in carbon disulphide for sut -cie-nt pe riod, usually three or four hours. The stock may be somewhat broken up or shredded beeters.

twice its own welght of water is added to the prior toits treatment with carbon disulphide. After completion of the Xenthate reaction,

water is added to make it water paste which will just flow out of the containers into the To provide this, approximately stock. Thispaste isthoroughly mixed and goes to the heaters where it is mixed with the remaining untreated paper stock and-with the ordinary sizing. The operation from this point on may be identical with that ordinaily used in 'manufacturing paper products.

-lVl1ere the emulsion of the gum does not break in the beater, but has to be broken by chemicals, it IS important that'the chemicals used to break the emulsion should besuch as do not affect the xenthate. Thus, the use of tion, which is best claims.

2i preferred way of practising my improved method, it will be understood that major changes in the apparatus and even changes in the method described may be made Without departing from the scope of my invendefined in the following I claim 1. The method of producing a sized xan-.

thated fibre which comprises permeating the fibre with the size prior to Xanthation and then Xanthet-ing the fibre.

2. The method'of producing a, sized Xantheted fibre which comprisesimmersing the fibre in almth of sodiumhydroxide which is it carrier for a sizeemulsion, and subsequently completlng xztnthatlon by carbon dlsulphide.

As a new article of. manufacture, a- .bmder for paper stock comprislng. cellulose fibres eXterio-rly Xanthztted but interiorly not Xanthated and permeated with a waterproofing size.

In testimony whereof, I have signed my name to this specification.

WILLIAM W. CARTER.

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