US1792351A

US1792351A - Process of producing paper stock

Info

Publication number: US1792351A
Application number: US34738A
Authority: US
Inventors: Harry P Bassett
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-06-03
Filing date: 1925-06-03
Publication date: 1931-02-10
Anticipated expiration: 1948-02-10

Description

Patented Feb. 10, 1931 PATENT OFFICE HARRY 1. BASSETT, OF CYNTHIANA, KENTUCKY PROCESS OF PRODUGHTG PAPER STOCK No Drawing. Application filed June 3,

.This invention relates to the production of paper stock and is, in part, a continuation of my copending application, processes of producing paper stock, filed July 25, 1921, Serial An object of the present invention is the production of paper stock which is hydrolyzed to such an extent that suflicient vegetable mucilage or hydrated cellulose will be formed to properly cement the fibre together without resorting to prolonged or extensive beating. i

In the manufacture of paper stock from cotton linters, or other fibrous material, it

has heretofore been necessary to properly condition the fibres for hydrolysis. The physical construction of cotton fibres varies to such an extent that any attempt to hydrolyze them by processes heretofore used without preliminary beating will result in the complete hydrolyzation of the more tender fibres before the more resistant ones have been'afiected. It has heretofore been necessary to resort to prolonged and extensive beating prior to hydrolyzing in order to break 'up the more resistant fibres.

In the present invention, I have found that the fibres may be properly prepared by a slight beating operation while the fibres are in a weak acid condition and I attain this result by treating the fibres with a weak acid solution or a solution of an acid salt during the beating operation. In the combined beat ing and acid treatment, I preferably employ 3 a mineral acid such as sulfuric acid or a mineral acid salt of approximately .05 per cent strength to l per cent strength by weight 7 at a selected temperature above 20 C., and not materially in excess of 100 C. and then 40 treat the material with a solution of an alkali.

The alkali treatment may be preceded by the' 1925. Serial No. 84,738.

preferably a weak solution of sodium hydroxide of less than 2 per cent strength, a soda pulp is-formed. When this material is formed, it is subsequently submitted to a combined acid and beating treatment with a solution of an acid or an acid salt, such as sulfuric acid of approximately .05 per cent to 1 per cent strength at a selected temperature above 20 0., but not materially in excess of 100 0., an acid pulp is formed, the cellue lose molecules of the fibre being hydrolized.

I have found that when the fibres are submitted to a slight beating operation when in an acid condition, as by treating with the acid in the manner set forth, during the beat- 5 ing operation a product is obtained which will completely pass through the screen. On the other hand, if the same percentage of acid and alkali is employed and the fibres merely submitted to a slight beating operation when 7 in an alkali condition, the resulting product will not pass through the screen. The product obtained by submitting the fibres to a slight beating operation when in acid-condition, may be employed either alone or in admixture with sulfite pulp or similar pulp in the manufacture of paper.

In a typical embodiment of the process wherein the preliminary acid and beating treatment is employed, cotton linters or other 30 cellulose fibre is placed in a heater and treated during the beating operation, with a weak solution of an acid, preferably a mineral acid, such as sulfuric acid, or an acid salt of approximately from .05 per cent. strength to 5 1 per cent. strength by weight at a selected temperature above 20 (3., and not materially in excess of 100 (3., from one-half to four hours. As stated, it is essential that the material be in an acid condition when submitted to the-beating operation and I preferablyem loy a combined acid and beating treatment m which the acid solution is added to the material in a beater. The material is then washed to remove the acid and treated with a solution of an alkali, preferably a solution of sodium hydroxid of less than 2 per cent. strength to form soluble organic salts. It is then washed to remove the soluble organic salts. I have found that if this soda pulp is then treated with an acid or an acid salt, preferably sulfuric acid, or sodium acid sulfate of from .05 to 1 per cent. strength at a temperature of from 20 to 100 C., an acid pulp is formed in which the fibres have been sufficiently hydrolyzed to produce suificient vegetable mucilage to cement them together.

In this acid treatment, the cellulose molecules are hydrolyzed and a vegetable mucilage is formed. The material may be employed in the manufacture of paper either along or in admixture with paper stock formed by the usual sulfite process, or other paper stock of like character.

The process may be performed by first treating the cellulose fibres with a weak solution of an alkali, preferably a weak solution of sodium hydroxide of less than 2 per cent. strength and then performing the combined acid and beating treatment above described.

Where a soda pulp is desired, the subsequent acid step is elminated, and the fibres submitted to the first acid treatment and the alkali treatment.

The character of the material obtained may, in either case, be determined by testing the viscosity of solutions formed by dissolving a small quantity of this cellulose or cellulose compound formed therefrom in a suitable solvent such as cupra-ammonia, or the like. In either case, the character of the resulting material may be controlled by variation of the acid strength, the temperature, or time of treatment. By employing variations in acid strength, temperature and time of treatment, materials may be obtained capable of forming cellulose containing solutions of a desired viscosity. If, for example, acid of .05 per cent. strength is used, the resulting material will be capable of forming a cellulose containing solution which will have a higher viscosity than if acid of higher 'strength within the range of from approximately .05 per cent. to 1 per cent. is used. Similarly, in the treatment of fibre with weak acid of a predetermined strength, the viscosity of a solution formed from the resulting material will be higher if the hydrolysis is carried out at 20 C., than if carried out at a higher temperature within the range of from 20 C. to 100 C. With the acid strength and the temperature remaining constant, a material capable of forming solutions of higher viscosity will be obtained by shortening the time of treatment.

After the material has been treated with sodium hydroxid or other alkali, either with or without the preliminary combined acid and beating treatment, materials capable of forming cellulose containing solutions of a relatively high degree of viscosity can be obtained by the use of an acid solution of a strength near the lower range of acid strengths set forth at a temperature somewhat below 80 C. I can obtain materials capable of forming solutions of a fairly high viscosity by conducting the hydrolysis at a temperature as low as 20 C., and I have obtained the bestresults in producing solutions of high viscosity by the use of acid of about .05 per cent. acid strength at a temperature of about 80 C. In producing materials capable of forming solutions of medium viscosity, the soda pulp is hydrolyzed at a temperature of about 90 (3., using acid of a desired strength approximately from .05 to 1 per cent. of acid but as I prefer to hydrolyze at about 80 C. where a solution of low viscosity is not required, I prefer, in the treatment of materials for use in forming solutions of medium or relatively low viscosity to employ an acid of from approximately .25 per cent. to 1 per cent. strength at a temperature of about 80 C.

In producing solutions of low viscosity, I use acid of about 1 per cent. strength at a temperature of about 100 C.

From my experiments, it appears that the character of the'material to be obtained may be regulated by an acid treatment subsequent to the alkali treatment with or without a preliminary combined acid and beating treatment, or may be regulated by a preliminary acid treatment with or without subsequent acid treatment. Of the factors affecting the character of the material produced, the temperature at which the hydrolysis is conducted is more important, and a considerable range of difference in the character of the material and the viscosity of solutions formed therefrom is obtainable by merely varying the temperature at which the acid treatment is carried out, but to obtain the widest range of difierence in the character of material, and the viscosity of solutions formed therefrom, it will be understood that the temperature within the limits set forth, the time of treatment, and the strength of the acid within the limits set forth must be varied in accordance with the invention, the viscosity being correspondingly increased as weaker acid within the range of from .05 to 1 per cent. strength is used, as a lower temperature within the range of from 20 C. to 100 C. is employed, and as the time of treatment is shortened.

The degree of strength of the solution of alkali employed does not appear to affect the viscosity of the cellulose containing solution. I prefer, however, to employ a solution of from 1 to 2.5 per cent. strength of a basic compound of an alkali or alkaline earth metal, preferably sodium hydroxid. It will, of course, be understood that the subsequent acid treatment will be continued until the gummy constituents of the cellulose fibre are completely hydrolyzed as can readily be determined by theexamination of a test sample and that in the treatment of fibre of a uniform grade, a duration of treatment found by examination tobe satisfactory will be followed. Similarly, the alkali treatment will be continued until the hydrolyzed gums are wholly converted into soluble bodies and the washing operations con tinued until the soluble bodies are removed.

If the purified fibre is to be bleached, I may employ any of the well known bleaching treatments, but I prefer to employ a solution of calcium hypochlorite of about .5 per cent. strength.

While I have described in detail the preferred practice of my process, it is to be understood that the details of procedure, and proportions of ingredients may be widely varied, and that known chemical equivalents v may be employed in place of the materials mentioned without departing from the spirit of the invention or the scope of the subjoined c aims.

I claim:

1. The process of making paper stock which comprises submitting cotton linters or like fibrous material to a combined slight beating and acid treatment with a weak acid solution containing a selected per cent. of acid between .05 and 1 per cent. strength at a temperature between 20 and 100 C. to effect partial hydrolysis of the material, and treating the material with a weak alkali solution after the combined acid and beating treatment.

2. The process of making paper stock which comprises submitting cotton linters or like fibrous material to a combined slight beating and acid treatment with a weak acid solution containing a selected per cent. of acid between .05 and 1 per cent. strength at a temperature of substantially C. to efiect partial hydrolysis of the material and treating the material with a weak alkali solution after the acid treatment.

3. The process of making paper stock which comprises submitting cotton linters or like fibrous material to a combined slight heating and acid treatment with a weak acid solution containing a selected percentage of acid of less than 1 per cent. strength at a temperacomprises submitting cotton linters or like fibrous material to a combined slight beating and acid treatment with a weak acid solution to efi'ect partial hydrolysis of the material, washing, treating the resulting material with a weak alkali solution, washing, and treating the material with an acid solution containing a selected quantity of acid of less than 1 per cent. strength at a temperature between 20 and C.

6. The process of makingpaper stockwhich comprises treating cotton linters or like fibrous material with a weak alkali solution, and submitting the material to a combined slight beating and acid treatment with a weak acid solution containing a selected per cent. of acid between .05 and 1 per cent. strength at a temperature between 20 and 100 C., after the alkali treatment.

7. The process of making paper stock which comprises treating cotton linters or like fibrous material with a weak alkali solution, and submitting the material to a combined slight beating and acid treatment with a weak acid solution containing a selected per cent. of acid between .05 and 1 per cent. strength at a temperature of substantially 80 C., after the alkali treatment.

8. The process of making paper stock which comprises treating cotton linters or like fibrous material with a weak alkali solution,

and submitting the material to a combined slight beating and acid treatment with a weak acid solution containing a selected per cent. of acid of less than 1 per cent. strength at a temperature between 20 and 100 (1, after the alkali treatment.

In testimony wherof, I afiix my signature.

HARRY P. BASSETT.

ture between 20 and 100 C. to efiect partial hydrolysis of the material, and treating the resulting material with a weak alkali solutionafter the acid treatment.

4. The process of making paper stock which comprises submitting cotton linters or like fibrous material to a combined slight beating and acid treatment with a Weak acid solution to effect partial hydrolysis of the material, washing, treating the material with a weak alkali solution, washing, and treating the material with a weak acid solution containing a selected per cent. of acid between .05 and 1 per cent. strength at a temperature of substantially 80 C.

5. The process of making paper stock which