US1710752A - Wood-pulp material - Google Patents

Description

Patented Apr. 30, 1929.

UNITED STATE-S v 1,710,752 PATENT OFFICE.

JOSEPH H. WALLACE, OF BROOKLYN, NEW YORK, ASSIGNOR T0 PINE WASTE PROD- i UCTS, INCL, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

WOOD-PULP MATERIAL.

No Drawing. Application filed July 29,

This invention relates to the materials used for the manufacture of paper pulp, and has for its object to provide an efficient and at the same time a relatively cheap material for paper pulp which can be produced by inexpensive methods and in practically unlimited quantities.

The manufacture of paper pulp from wood by chemical processes involves what may be called a fractional or selective attack upon the wood components; theobject being to produce a disintegration or solution of certain relatively less resistant components while leaving unattacked or unacted on certain relatively resistant components or cellulose. The yield andquality of product depend largely upon the care withwhich the operation is performed; upon the observance of conditions which have been empirically established by long practice. The greater the exactitude with which these conditions can be observed, the better the results; but, for various reasons, the ordinary practice is not standardized to the degree which is desirable. It is an object of the present invention to promote accuracy and uniformity of operation by the rovision of a raw material, all parts of w ich are of. the same characteristics; thereby facilitating the operation. With such raw material all parts thereof will be uniformly digested with solutions of exact and standard composition, in the same length of time.

Wood is a variable material; and particularly as regards moisture content and the content and character of eXtractives?,-- non-fibrous components. These variables much influence the operation in pul making. In the alkaline processes, with the production of raw materials ,for which the present invention is chiefly, though not exclusively, concerned, variations in the amount and character of the moisture in. the wood and of the acid extractives therein make much difference in the activity of an alkali solution of given strength on diffgrent chips or on different parts of the same c ip.

In the soda and sulfate processes, chipped wood in fragments long enough to give the desired length of fiber, is heated in a'digester under pressure with an alkaline liquid to give a disintegration and solution of the non-cellulose portion of the Woody fiber, or lignin, and a removal of the various-ex- 1925. Serial No. 46,878.

with southern pine, the amount of acid res-- ins present in some of the chips, or in some parts of them, is so great as to rendertreatment of such wood by the ordinary alkaline processes very difiicult. With any resinous wood the amount of resin varies from log.

to log; and in the same log, or chip, from point to point. Variations in moisture conent accompany variations in 'resin content. Resinous and gummy woods, and resinous and gummy partsof wood, absorb less moisture than non-resinous or less resinous, or non-gummy or less gummy parts.

In all alkaline processes, after the comple tion of the digestion, or the pulp making operation proper, the black liquor is withdrawn, evaporated, charred and burnt in order to recover the alkali for reuse; and much of the economy of operation depends u on the efliciency of the alkali-recovery. he process is, therefore, an integral one; conditions affecting alkali recovery must be considered as well'as, and in connection with, conditions affecting the digestion only. In the digestion resin is desirable as its presence facilitates the action; and in the black liquor it is still more desirable as adding fuel value to the residues, thereby aiding materially in the final combustion prior to recovering alkali. It is not, however, in either case necessary or desirable that it be-an acid resin.

According to this invention, when applied to southern pine, for example, coniferous wood of any kind is chipped into pieces of the size wanted for paper pulp mill work, say from to inch in length, by to 1 inches in width and to inch in thickness and these are submitted to a brief treatment with a suitable solvent; such as is usually employed for extraction purposes, the treatment being merely long enough to effect an even distribution of the residual resin.

In this treatment of the chips a number of important advantages are secured' The chips are opened up to the penetration of the digestor liquors and made uniform in this Way. In an unextracted chip, of southern pine some cells are full of resinous matter and aqueous liquids penetrate only slow- 1y while other cells are more pervious. In

the treatment with a solvent all the cells are made. readily permeableqand the cells originally non-resinous now contain resin while those originally full of it, are partially emptied; or, in other words, the resinous matter becomes equally distributed throughout the chip; and also from chip to chip of the charge. The whole charge in the extractor is made, more or less, uniform. IVith this equalizing of resin content comes an equalization of moisture. The chips are readily brought to a standard moisture content (usually about 20 per cent) by exposure to a damp atmosphere; or by a slight drying in the event that after extraction steam has been used to remove residual solvent, as is usually the case. The chips tend to retain this standard moisture content without much variance by exposure to the atmosphere. The treatment, further, leaves the chips somewhat porous and compressible, rendering it easy to bale them under pressure; and in bales the standard moisture content is of course still more easily preserved.

In distributing the resin content, the acid content of the wood is also distributed; that is, the amount of soda which will be nontralized in the digestor is made standard.

In a specific embodiment of my invention, southern pine in any form (light wood, stumps, saw mill waste, etc.) is cut into pulp .makers chips and given a brief treatment with a solvent. Any one of many known solvents may be used. After the treatment,

residual solvent is removed as by steaming in the usual way. Steaming at this stage probably contributes materially to the described equalization of residual resinous matter. The steamed chips are then given a slight drying to bring the moisture to a standard amount, usually about 20 per cent, and are then baled.

By means of my invention it will be seen that the pulp manufacturer is for the first time in the history of the art supplied with a standardized material suitable for the manufacture of high grade pulp-and one which can be relied upon to produce uniform and satisfactory results. Because of the uniform distribution of the resin content in the chips, the chemicals used in cooking will act upon all of the chips and in all parts of each chip to the same degree. i

With such a treatment as is above described the chips are not injured or stained materially by the metal of the apparatus, nor is either the wood or resinous material injured by long heating.

After the chips have been subjected to the aforesaid treatment they may be digested and disintegrated with an alkali solution such for example as a hot solution of caustic soda or of a combination of caustic soda with sodium carbonate, sulphide, or sulphate. The cellulose is thus made into paper pulp, and the-resins, oleoresins and terpenes go into the spent alkaline solution. This invention includes the recovery of such matters from the spent alkaline solution, but not the specific way of doing it. One method of recovering the resinous and gummy matters from the spent alkaline solution is disclosed in Patent No. l.511,461, issued to Frank E. Greenwood October 14, 1924. Two other methods which are suitable for this purpose are disclosed in copending applications, Serial Nos. 405,921 and 405,923,-filed August 25, 1920, by said Greenwood which have matured as Patents Nos. 1,560,420 and 1,593,656 issued Novemher 3, 1925 and July 28, 1926 respectively.

In an application, Serial No. 405,964, on which Patent No. 1,560,447 was issued November 3, 1925, I have described a process for making pulp chips of resinous coniferous wood, by treating the chips with a solvent until some of the extractives are removed. In another application Serial No. 405,965, on which Patent No. 1,560,446 was issued November 3, 1925, I have covered pulp mill chips made by the aforesaid process of Serial No. 405,964, and in a third application Serial No. 405,963 onwhich Patent No. 1,560,448 was issued November 3, 1925, Ihave claimed the combination of treating chips of coniferous wood with a solvent to remove part of the extractives, pulping the chips in an alkaline solution, and recovering the residue of the resinous matter from the spent alkaline solution. The three aforesaid applications were filed August 25, 1920 and were copending herewith. In application Serial No. 405,965, I pointed out that in the first treatment the texture of the wood was rendered porous, that the resinous matter was distributed through the individual chips and 1 throughout the mass of the chips, and that the moisture content was thereby standardized. It is obvious that these features are of great value even if none of the resinous matter is removed from the chips as a whole. It is to protect this feature of my invention that this present application is filed.

What I claim is:

1. As a new material, pulp mill chips of coniferous wood containing a substantial proportion of the entire resinous content of said wood and having said resinous content distributed to render the texture of said chips substantially uniform.

2. As a new material, pulp mill chips of coniferous wood containing a substantial proportion of the entire resinous content of said wood and having said resinous content distributed to render the texture of said chips substantially uniform, and having a uniform moisture content.

3. As a new material, pulp mill chips of coniferous wood containing a substantial proportion of the entire resinous content of said wood and having said resinous content distributed to render the texture of said chips substantially uniform, and having a uniform moisture content and baled to preserve the moisture content.

4. The process of producing material for pulp mills which consists of reducing resinous coniferous wood to pulp mill size chips, dissolving the resinous and gummy matters in said chips and producing an open porous texture in the wood to thereb distribute with greater uniformity throug out the individual chips and throughout the mass of the chips said resinous and gummy matters, by treating said chips with a solvent without removing a substantial proportion of the resinous and gummy matter in the mass treated.

5. The herein described process which consists of reducing resinous coniferous wood to pulp mill size chips, treating said chips with a solvent to distribute their resinous and'gummy contents without removing a substantial proportion of the resinous and gummy matter in the mass treated, disintegrating the chips with heated alkaline solution to form pulp, and recovering the resinous and gummy matters from the spent' alkali solution. 7

In witness whereof, I have hereunto set my hand this 22nd day of July, 1925.

JOSEPH H. WALLACE;