US1697907A - Cellulosic material and product obtained therefrom - Google Patents

Description

P atente'cl Jan. '8, 11929.

HENRY DREYFUS, OF LONDON, ANDCLIFFORD IVAN BY, ENGLAND, ASSIGNORS-TO OELANESE CORPORATION OF AMERICA, A GORPORA- 'TION OI DELAWARE.

OELL'ULOSIC MATERIALAND PRODUCT OBTAINED THEBEFBJOM.

No Drawing. Application filed January 19, 1927,

This invention relates to the treatment of cellulosic materials for the purpose of rendering them more reactive for esterification and especially acetylation and also to the production of cellulose acetates or other cellulose esters from said treated materials.

We have now discovered that cellulosic I materials can be rendered more easily esterifiable by treatment with small quantities.

of formic acid.

Theuse of small proportions of formic acid is especially valuab e in that it is not necessary to subject the cellulosic material to an after treatment for the removal of the formic acid, such as is necessary in the case where larger proportions of formic acid are used. ,As will be readily understood, in the case where the cellulosic materials are acetylated directly after pretreatment with formic acid, the formic acid in the cellulosic material is destroyed by the acetylating medium used in the subsequent acetylation,

. the acetic anhydride being simultaneously converted into acetic acid. This by-reaction would occasion a considerable wasta e'of acetic anhgdride where large quantitles of formic aci are present, but the loss of acetic 'anhydride is relatively small when only small quantities'of formic acid are present.

By the use of small quantities of formic acid in the pretreatment it becomes possible therefore to proceed directly to the esterification of the cellulosic material, without any intermediate treatment for the removal of formic acid b' evaporation, or by washing with water ollowed by a drying operatlon, or by other methods.

Good results are obtained by the use of 10 to 20 parts by weight of formic acid to each 100. parts by weight of cellulosic materials, though'the proportions of formic acid used may be greater or less than those indicated. In using very small proportions of formic acid care-must be taken to ensure that the cellulosic materials are evenly moistened with the formic acid, while the use of formic acid in proportions exceeding 20 or at most I 30% of the cellulosic material onlyfleads to an increase in the wastage of acetic ,anhy dride without any material advantage in other directions. I The formic acid may be employed in a concentrated form or diluted with water Serial No. 162,218, and in Great Britain October 8, 1928.

nanny, or sronnon, NEAR nnnor other diluent. For instance, 100% formic I acid, or aqueous solutionsfcontaining. 50- 100% preferably 70-90% be used, or mixtures 'of formic acid and acetic acid many desired proportion may also be employed.

As cellulosic materials, we employ cotton, cellulose (in either the mercerized or the nonmercerized form) or wood pulp, the latter having been preferabl first submitted to an alkali treatment $110 as indicated in the British specification No. 249,17 3 and corresponding U. S. application S. No, 747,054,

formic acid, may

or other cellulosic materials or their converslon products. The cellulosic material used may contain the usual amount ofmoisture for example, 4% to 6% or 8%, or maybe freed from moisture by drying.

In practising the. invention, the formic acid is distributed evenly over the cellulosic material, for instance, by spraying, the cellulosic material being turned or moved from time to time if necessary to ensure uniformimpregnation with the formic acid. The cellulosic material is then allowed to stand until a product capable of rapid esterification is obtained.

The time occupied varies with the nature of the cellulosic material, the concentration of the formic acid, the temperature at which the cellulosic material is maintained, and

the degree of reactivity required in the product. The treatment proceeds quite satisfactorily at ordinary temperatures but may if desired be accelerated by the use of increased temperatures. p

In the subse uent esterificatipn due allowance should e made for the destruction of theesterifying agent by the formic acid present and any .;water introduced therewith, particularly when workingby processes in which minimum quantities of the esterifymg medium are used. Thus in acetylation processes, the amount of acetic anhydride is increased by an amount suflicient to convert the water formed by decompositionof the formic acid, together with any water mixed therewith, to acetic acid.

The products may-be acetylated with ease and rapidity by any of the usual processes employed for this purpose, provided that the proportion of acetic anhydride is increased in the manner previouslyindicated, the prortion of acetic acid added being preferably.

iminished by an amount corresponding wi that formed from theexcess of acetic anhydride employed.

The treatment may be. efiected in the manner described in the following example, it being understood however, that this example is not to be regarded as limiting the inventioninanyrespect.

- Example 1-. 100 parts of cellulose dried or conta' g for instance 5-6% of moisture, are spraye with about 15 parts of 7 585% formic acid. The cellulose is allowed to stand'until the desired degree of reactivity has been reached, for instance for 8-12 hours, and is afte" wards added to an acetylating bath.

I Example 2.

100 parts of cellulose, dried or containing 56% of moisture, are moistened with about 20 parts of a mixture containing -40% of formic acid'and -70% of acetic acid.-

After the desired degree of reactivity has developed, the celluluose is acetylated.

The acetylation suitable process, and especially by the processes described in British specifications Nos. 14,101 of 1915,

101,555, corresponding U. S. Patents Nos.

1,278,885, 1,280,974 and 1,280,975, British- 207,562 and corresponding S. application S. No. 633,016 filed 18 April, 1923, but in the case of cellulose that has been pretreated in accordance with the gpecification No.

foregoing example we use about 50 additional parts b weight of acetic anhydride to compensate or the wastage which takes place as the result of the formic acid in the cellulose.

Thus, to aoetylate 100 parts of pretreated cellulose, we ma use 900to 1000 parts by weight of glacia acetic acid, 10 to 15 parts by weight of parts by weight of acetic anhydride.

What we claim and desire to secure by Letters Patent is 1. A rocess for treating cellulosic'material w ich comprises treating said cellulosic material with a small proportion of formic acid, thereby producing a cellulose which is highly reactive for esterification.

2. A rocess terial w 'ch comprises treating said cellulosic material with a small proportion of an aqueous solution of formic acid, thereby producing a cellulose which is highly reactive for esterification. I

8. Apfocess for treating cellulosic material w "ch comprises treating said cellulosic material with a small proportion of formic acid of at least 50% concentration, thereby ly reactive for esterification.

.a mixture containin may be performed by any presence of the sulphuric acid and 250 to 300 for treating cellulosic maproducing a cellulose which is high- 4. A rocess for treating cellulosic material which comprises treating said cellulosic material with a small proportion of formic acid of at least concentration,

thereby producing a cellulose which is highly reactive for esterification.

5. A rocess for treating cellulosic material w 'ch comprises treating said'cellulosic material with a small proportion of formic and acetic acids, thereby producing a cellulose which is highly reactive for esterification.

6. A process terialwhich comprises treating said cellulosic material with a small pro ortion of an aqueous mixture containing ormic and acetic acids, thereby producing a cellulose which is highly reactive for esterification.

7. A process for treating cellulosic material which comprises treating said cellulosic material with a small proportion of for treating cellulosic ma- 0 an aqueous mixture containing at least 50% v of formic and acetic acids, thereby producing a cellulose which is highly reactive for esterification.

8. A process for treating cellulosic material which comprises treating said cellulosic material with a small proportion of an acqueous mixture containing at least 70% of formic and acetic acids, thereby producing a cellulose which is highly reactive for esterification. I

9. A process for treating cellulosic material which comprises treating said cellulosic material with a proportionnot exceeding 30%, calculated on the weight of the cellulosic material, of an'a'cqueous solution of formic acid, thereby producing a cellulose which is highly reactive for esterification.

10. A process for treating cellulosic material which comprises treating said cellulosic material with a proportion not exceed-' ing 30%, calculated on the weight of the co ulosic material, of an aqueous solution offormic acid, thereby producing a cellu-- lose which is highly reactive for esterification.

11. A process for treating cellulosic'material which comprises treating said cellulosic material with a proportion not exceedin 30%, calculated on the weight of the I ce ul osic material, of a mixture containing formic and acetic acids, thereby producing a cellulose which is highly reactive for esterification'.

and subjecting the resulting cellulose to the actionof an medium.

13. A process for treating cellulosic material which comprises. treating; said cellu- ,12. A process for treating cellulosic malosic material with a small proportion of an aqueous mixture containing formic acid, thereby producing a cellulose which is highly reactive for esterification, and subjecting the resulting cellulose to the action of an esterifying medium.

14. A process for treating cellulosic material which comprises treating said cellulosic material with a small proportion of a mixture containing formic and acetic acids, thereby producing a cellulose which is highly reactive for estcrification, and subjecting the resulting cellulose vto the action of an esterifying medium.

15. A process for treating cellulosic material which comprises treating said cellulosic material With a small proportion of formic acid, thereby .producing a cellulose which is highly reactive for. esterification, and subjecting the resulting cellulose to the action of an esterifying medium for the production of carboxylic acid esters.

16. A process for treating cellulosic material which comprises treating said cellulosic material with a small proportion of formic'acid, thereby producing a cellulose which is highly reactive for acetylation, and

subjecting the resulting cellulose to the action of an acetylating medium.

17. A process for treating cellulosic material which comprises treating said cellulosic material with a proportion not exceeding calculated on theweight of the cellulosic material, of an activating agent comprising formic acid, thereby producing a cellulose which is highly reactive for acetylation, and subjecting the resulting cellulose to the action of an acetylating me dium. I

18. A process for treating cellulosic material which comprises treating said cellulosic material With a proportion not exceeding 30%, calculated on the weight of the cellulosic material, of-an activating agent comprising formic and acetic acids, therebyproducing a cellulose which is highly reactive for acetylation and. subjecting the resulting cellulose to tlie action of an acetylating medium.

In testimony whereof we have hereunto subscribed our names.

-HENRY DREYFUS.

CLIFFORD IVAN HANEY.