US2047278A

US2047278A - Process for the fibrous esterification of cellulose

Info

Publication number: US2047278A
Application number: US671901A
Authority: US
Inventors: Carl J Malm; Charles L Fletcher
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1933-05-19
Filing date: 1933-05-19
Publication date: 1936-07-14
Anticipated expiration: 1953-07-14

Description

Patented July 14, 1936 umrso OFFICE;

PROCESS FOR THE 'FIBROUS "E STERI'FI-- GATION OF CELLULOSE CalrleJ.'Malm; Rochester, N.-Y., and Charles-Lt Fletcher, Kingspor-t; Tenn., c assignors to ,East-l. man {Kodak Company, Rochester, N.Y.; alcor-V poratioh. ,of New York Nd:Di'awi1ig-. Application May=:19; 1933;\-

SerialNo. 671,901

9 Claims, (0]. 2602-101),

Theipresentinvention relatesto:a fibrous =proc-r ess of "esteriiyingl'cellulose-:1n which a; liquid sat-1 uratedr hydrocarborriis eemployedrr as: the? nonsolvent andt chlorinated:hydro'carbon.:isremployed aresuitablein:fibrouszesterificationrprocesses 'arer knowm under various :names :"suchas 1igroin,ii;pe-:= troleumr:ether;1Stoddard 'zsolvent, kerosene: gasoe 1ine,naphtha-, etc. 7 Stoddard 'solventuisaa commonly :knownzfaliphatic hydrocarbon? which? is 116- scribed'intfiBureaumf Standards 'BiiIIetin CS *3L28 (1929 )1: In .the=fibrous processes wherezsthese sat uratedarhsrdrocarbbns are! employed'sasethe none-.-

solventszc: in: the r esterifi'cation-w of cellulose the-e amounts :necessaryaofassure insolubility of the 1 resulting :esteriin'the festerification *b'athare mu'chf less thanizisrthe casez'withthe non-solventsswhich are'vordinarilyf employed. However these nonsolventsssuffer the disadvantage that their mixtures with 'the lower fatty acids and anhydrides are heterogeneous especially in those cases where 4 hydro-carbons havingsta -hig'h#boiling range are I employedi 1 O'ne object of 'our inventibn is to provide a proc-= ess for the fibrous esterificat-iozr =ofcellulose in which a saturated hydrocarbon may be empldyed as the non-solvent zand"yetithe bath is homoi geneousand from which the-non=solvent and homogenizing'diduid may-be easily removed after -1 the completion of 'theestrificationr Another ob' ject of our inventibn is to "p- IOV-idanfiBlOHS proc= h ess-for the esterification' of cellulose irr'whichthe: recovery of the individual ingredients is facilitated.

The broad idea of =employing a homogeniz'er I in conjunction with a saturated-hydrocarbon in v the fibrous-esterification oi cellulose isthe inven- "tion of Minsk, Kenyon and Gray andis disclosed and claimed in their" application" Serial No. 671,9003'fi1ed of even date. We'have found that if certain chlorinated hydrocarbons are employed a-fib'rousesterification bath' in which a satu o ratedhydrocarbon isthe non-solvent, the sepa= ration and recovery of thejingredients offth'e spent esterifi'cation" bath" is" greatly facilitated. We have foundthat the halogenated hydrocarbons are especially suitable' as homogenizers: in fibrous esterificationprocesses; as they may re-' plaoeether fatty. vacidxordinarily employed in diam,- esterification mixture andrtheyoformganeazeo- J tropic1constants:boilingamixture with::-water. We have found that by ourlinyention; manyrrofithe diflicult and. often unsatisfactory methods of recovering the ingredients of a spent fibrous esterification bath are eliminatedzwhich have :been heretoforerthoughtinecessary-xor atrleast prefer-:- able in sucht'recoveryn Inna fibrous:esterification process .inxwhich'a 10 :1

saturated hydrocarbonaisremployed-v as the nonsolvent, a surprisingly smalh amountiofx that hy-: drocarbon is necessary to :render theesterification bath nonesolvent I of ithelcellulose ester: formed,

in'fact, thenon solvencyof this-liquid is sorpro- 15 nounced: that'it *extendswven to the constituents of: 'the esterification bath; By the: present invention: the effectiveness of the saturated hydrocarbon te -induce non-solvency of the cellulose ester" by-theesterificatiom bath-"may be utilized and an even esterification of the cellulose may be assureds p The-halogfenated hydrocarbons when employed as homogenizers also present'other advantages in additiontcthose -pointed outabove. Many of themare inflammability reducing agents which feature-is--very"valuab1e:in case of the more vola-, tile: hydrocarbons :such as gasoline: or the like; For "instance: a mixture of ""parts of trichlorethylene and EOparts'of Stoddard solvent is total- 1y non-inflammable. Even in ,the case of a halogenated hydrocarbon such asethylene chloride which will burn; that material-has a-.comparativelylhighcfiash point soithat the-dangerzof ignition is much less:comparedowithsome of the othershomogenizers which? might be employed. The halogenated hydrocarbons are excellent 501- vents-.forthe ingredients of the esterification bath and 'in. the case: ofesome of these hydrocarbons suclrasethylene vchloride the amount required for homogenizing: is less than that required when using some otherhomogenizing liquid. We have found that ethylene chloride; propylene chlorideand'trichlorethylene are the most satisfactory in our "invention however "other chlorinated hydrocarbons such -asmethylene ch1oride, -carbon tetrachloride, chloroform or other halogenated hydrocarbons "may; be employed with marked success. The bromide,- iodijde-- and fluoride compounds which correspond to the chlorinated; hydrocarbons-would also be suitable for-homogenizing esteri-fication baths which wouldotherwise be heterogeneous.

Our process comprises the esterification of. cel-. lulose izra bath comprisinga fatty acid anhyformed, by centrifuging. The cellulose ester now contains less than an equal weight of liquid which consists of the non-solvent, the chlorinated hydrocarbon, a small quantity of fatty acid and the catalyst. The ester is then placed in a vessel adapted for steam distillation and water andv a sufficient quantity of sodium carbonate to neutralize the catalyst is added. The chlorinated hydrocarbon and the non-solvent may be removed by steam distillation. The quantity of fatty acid remaining is negligible and may be economically discarded. The ester is washed with water to remove the fatty acid and sodium' salt and may then be dried.

The following examples illustrate processes which embody our invention:

Example I 30 lbs. of cotton linters were added to a mixture of 90 lbs of Stoddard solvent, 90 lbs. of acetic anhydride, 120 lbs. of ethylene chloride and 810 c. c. of a catalyst consisting of 3 parts by volume of phosphoric acid and 1 part by volume of sulfuric acid all at a temperature of F. The mixture was stirred occasionally and the temperature in the jacket of the reaction vessel was raised uniformly to a temperature of 120 F. over a period of 4 hours. The mass was maintained at that temperature until a washed and dried sample taken therefrom showed solubility in a mixture of parts of chloroform and 15 parts of ethyl alcohol by volume. This usually requires 10-15 hours.

The fibers were then separated from the main portion of the reaction liquid by centrifuging. The remainder of the reaction liquid was removed from the fibers by adding water containing sufiicient sodium carbonate to neutralize the catalyst, steam distilling out the ethylene chloride and Stoddard solvent and washing out the remaining acid with water. The product which was a cellulose triacetate was dried in the usual manner. 7

Example II 30 parts of cotton linters were added to a solution consisting of lbs. of Stoddard solvent, lbs. of propylene chloride, 60 lbs. of 85% acetic anhydride, 45 lbs. of 94% propionic anhydride and 200 c. c. of sulfuric acid as the catalyst, all at a temperature of 70 F. The temperature in the jacket of the reaction vessel was raised uniformly to 120 F. over a period of 4 hours andthe temperature was maintained at this point until the product was soluble in a mixture of 90 parts of ethylene chloride and 10 parts of methyl alcohol by volume. The product, cellulose acetate propionate was processed as in the preceding example to remove the reaction liquid therefrom.

Although the present invention will be ordinarily applicable to fibrous processes in which the petroleum distillates are employed as the nonsolvent, it is obviously applicable to the use of any non-solvent which renders the esterification bath heterogeneous thus necessitating the presence of a homogenizer to assure an even esterification. In these processes the fatty acid ordinarily employed may be entirely replaced by the halogenated hydrocarbon in accordance with our invention however if desired this substitution of halogenated hydrocarbon for fatty acid may be only parrtial and the process would still fall within the scope of our invention.

It is to be understood that our invention is directed broadly to the preparation of organic acid esters of cellulose although as the simple and mixed esters of cellulose containing acetyl, propionyl and butyryl groups are more common at the present time, our invention is more particularly directed to the preparation of cellulose esters containing one or more of those lower fatty acid groups.

We claim as our invention:

1. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and a halogenated hydrocarbon, in sufficient amount to assure compatibility of the ingredients'of the bath, which bath will not dissolve the ester formed therein.

2. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of'40-210" C. as the non-solvent and a chlorinated hydrocarbon, in sufficient amount to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

3. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210" C. as the non-solvent and a chlorinated olefine, in sufficient amount to assure compati- 5 bility of the ingrediets of the bath, which bath will not dissolve the ester formed therein.

.4. A process or preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210" C. as the non-solvent and an alkylene chloride, in sufficient amount to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

5. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and ethylene chloride, in suflicient amount toassure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

6. Aprocess for the preparation of cellulose acetate propionate in fibrous form which comprises reacting upon the cellulose with a bath which contributes acetyl and propionyl groups to the cellulose and containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and an alkylene chloride, in sufficient amount to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

'7. A process for the preparation of cellulose acetate propionate in fibrous form which com- 75 prises reacting upon the cellulose with a bath which contributes acetyl and propionyl groups to the cellulose and. containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and ethylene chloride, in suflicient amount to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

8. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterifying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and propylene chloride in suflicient amount to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

9. A process for preparing an organic acid ester of cellulose in fibrous form which comprises reacting upon the cellulose with an esterii'ying bath containing a liquid petroleum distillate which is essentially within a boiling range of 40-210 C. as the non-solvent and trichlorethylene in sufficient amounts to assure compatibility of the ingredients of the bath, which bath will not dissolve the ester formed therein.

CARL J. MAIM. CHARLES L. FLETCHER.