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Publication numberUS3038814 A
Publication typeGrant
Publication dateJun 12, 1962
Filing dateJun 9, 1959
Priority dateJun 9, 1959
Publication numberUS 3038814 A, US 3038814A, US-A-3038814, US3038814 A, US3038814A
InventorsCipriani Cipriano
Original AssigneeCelanese Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cellulose ester solutions
US 3038814 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Unite poration of Delaware N Drawing. Filed June 9, 1959, Ser. No. 819,006 16 Claims. (Cl. 106-178) This invention relates to improved cellulose ester solutions.

Fibers and films of a cellulose ester are conventionally formed from a solution of the cellulose ester in an appropriate solvent. Various solvents are used for this purpose depending on the chemical nature of the cellulose ester. For example, there are two main types of cellulose acetate in commercial production, the secondary acetate which has an acetyl value below about 55% by weight as acetic acid, and the primary acetate or so-called triacetate which has an acetyl value above about 59%. In forming fibers and films, the secondary acetate is commonly dissolved in acetone and the triacetate in a mixture of methylene chloride and an alcohol such as methanol. While solutions prepared with these solvents are satisfactory in most respects, it maybe preferred in some instances to obtain solutions of cellulose acetate or other cellulose esters in solvents having somewhat different properties. More specifically, if it is desired to build a plant without extensive ventilating equipment, a solvent having reduced volatility and inllamrnability would be beneficial. In the case of cellulose triacetate, it may be desired to avoid the equipment necessary for the recovery of two separate solvent components. Furthermore, if wet spinning is employed, it may be advantageous to employ a solvent such that the extruded solution does not coagulate too rapidly thus allowing ample time for the filaments to be stretched and oriented. Finally it is often desired to form fibres and films from mixtures of cellulose esters and high polymeric materials of substantially different chemical structure, so that there is considerable need for solvents which are capable of dissolving both types of material.

It is an object of this invention to provide solutions of cellulose esters in relatively non-volatile solvents having reduced inflammability. It is a further object to provide solutions of cellulose esters in solvents which may be more easily recovered. It is a still further object to provide solutions of cellulose esters which coagulate less readily when wet spun so that the resulting filaments may be more easily stretched and oriented. It is a still further object of this invention to provide solutions of cellulose esters and other high polymeric materials which may be extruded into fibers and films. Further objects will become apparent from the following description of the invention.

In accordance with one aspect of the invention, the cellulose ester is dissolved in a solvent comprising a straight chain, aliphatic carboxylic acid'or an ester of such an acid, said acid or ester containing at least'one halide, sulfide or ethylenically unsaturated radical, or a halogensubstituted straight chain, aliphatic carboxylic acid nitrile.

- It has been found that these solvents are" capable of forming clear, gel-free solutions of desirable concentration and viscosity which are capable of being formed into useful One group of contemplated solvents are the halogensubstituted straight chain, aliphatic carboxylic acid, e.g.

halogen-substituted fatty acids such as dichloroacetic acid, trifiuoroacteic acid, and beta-chloropropionic acid (as a saturated solution in water.) The acid preferably has up to four carbon atoms. Also contemplated are alkyl esters of these acids, e.g. methyl chloroacetate, ethyl chlo- 3,038,8l4 Patented June 12, 1962 roacetate, methyl beta-chloropropionate and methyl alpha-chloropropionate.

Another group of compounds useful as solvents for cellulose esters are the halo-lower alkyl esters of straight chain, aliphatic carboxylic acids, e.g. of fatty acids, such as 2-chloroethyl acetate, chlorornethyl acetate, fluoromethyl acetate and 2-fluoroethyl acetate.

A further group of contemplated solvents are halogensubstituted straight chain, aliphatic carboxylic acid nitriles, e.g. nitriles of halogen-substituted fatty acids such a beta-chloropropionitrile and chloroacetonitrile.

A still further group of compounds suitable as solvents for cellulose esters are straight chain, aliphatic carboxylic acids containing a sulfide radical, e.g. mercapto-substituted fatty acids such as thioglycolic acid.

Also contemplated as solvents are ethylenically unsaturated, straight chain, aliphatic carboxylic acids. A preferred group of compounds are monoethylenically unsaturated acids, e.g. alkenyl carboxylic acids such as acrylic acid, and alpha-crotonic acid (in water solution). The unsaturated acid preferably has up to four carbon atoms.

The compounds useful as solvents are preferably liquid at room temperature, e.g. 22 (3., especially when used as the sole solvent. While solutions of cellulose acetate, especially the triacetate, are particularly suitable, other cellulose esters may also be dissolved in the solvents of this invention, e.g. cellulose carboxylic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate and mixed esters such as cellulose acetate-propionate and cellulose acetate-butyrate.

The cellulose ester may be dissolved in some of the solvents, e.g. halogen-substituted fatty acids, with another high polymeric material, e.g. high molecular weight linear polyesters of polycarboxylic acids and polyhydric alcohols such as polyethylene terephthalate, and high molecular weight linear polycarbonamides such as polyhexarnethylene adipamide, to form solutions which may be used to form fibers and films of the mixed polymeric material. If a polymeric component other than a cellulose ester is used it may be present in an amount, for example, of 1 to 80 percent by weight of the total polymeric material, depending on the specific nature of the other polymeric material.

Solutions of a cellulose ester and if desired another polymeric component may be formed having a wide range of concentration and viscosity, e.g. 1 to percent by weight of total polymeric material based on the Weight of the composition and a Brookfield viscosity at 22 C. of 300 to 7000 poises. If desired, the solvent of this invention may be mixed with other compounds to form a solvent mixture, the nature of the compounds depending on which solvent under the invention is being used. For example, beta-chloropropionic acid may be used as an aqueous solution.

The solution is formed into shaped articles such as fibers and films by subjecting it in a form having a crosssection with at least one thin dimension to a medium whereby the polymeric material is separated from most of the solvent and thus coagulated or precipitated. This may be done by contacting the solution with an atmosphere whereby the solvent is evaporated, e.g. as in casting or dry spinning, or by extruding the solution, as in wet spinning, into a liquid medium which is an nonsolvent for the polymeric material i.e. a coagulant or precipitant, such as liquids having a large proportion of water or methanol.

The invention is further illustrated by the following examples:

Example I Cellulose triacetate having an acetyl value of 61.5%

by weight and an intrinsic viscosity of 2.0 was dissolved at room temperature by stirring in dichloroacetic acid to yield a solution of 10% by weight of cellulose triacetate. The solution was clear, transparent, gel-free and had a Brookfield viscosity at 22 C. of 1040 poises. Satisfactory films could be cast from this solution.

Example 11 The same cellulose triacetate as in Example I was dissolved in methyl chloroacetate at room temperature to yield solutions of 13%, 15% and 20% by weight of cellulose triacetate. The Brookfield viscosities of the solutions at 22 C. were 1200 poises for the 13% solution, 3050 poises for the 15% solution, and 7000 poises for the 20% solution. The solutions were gel-free and transparent and could be cast into films which were also perfectly transparent and flexible and showed considerable toughness and resistance to bending. In addition, monofilaments could be extruded from a 0.1 mm. hole spinnerette into water which coagulated slowly even at 90 C.

Example III The cellulose triacetate of Example I was dissolved at room temperature in ethyl chloroacetate to yield a solution of 10% by weight of triacetate. Its Brookfield viscosity at 22 C. was 480 poises and it could be cast into satisfactory films.

Example IV The cellulose triacetate of Example I was dissolved at room temperature in 2-chl0roethyl acetate to yield a solution having 10% by weight of triacetate. Its Brookfield viscosity at 22 C. was 480 poises and it could be cast into satisfactory films.

Example V The cellulose triacetate of Example I was dissolved at room temperature in beta-chloropropionitrile to yield a solution of 10% by weight of triacetate. Its Brookfield viscosity at 22 C. was 300 poises and it could be cast into satisfactory film.

Example VI The cellulose triacetate of Example I was dissolved at room temperature in thioglycolic acid to yield a solution of 10% by weight of triacetate. Its Brookfield viscosity at 22 C. was 1080 poises and it could be cast into satisfactory film.

Example VII The cellulose triacetate of Example I was dissolved in trifluoroacetic acid at room temperature to yield a solution of 10% by weight of triacetate, having a Brookfield viscosity to 22 C. of 700 poises. The solution was clear and gel-free and could be cast into satisfactory film.

Example VIII The cellulose triacetate of Example I was dissolved at room temperature in acrylic acid to yield a solution of 10% by weight of triacetate having a Brookfield viscosity at 22 C. of 1000 poises. The solution was clear and could be cast into satisfactory films.

Example IX A mixture of 50% by weight of the cellulose triacetate of Example I and 50% by weight of polyethylene terephthalate was dissolved in dichloroacetic acid at room temperature to yield a solution of 10% by weight of total polymeric material having a Brookfield viscosity at 22 C. of 1700 poises. Film obtained by the coagulation of the dope in hot water dried with no shrinkage and was flexible.

Example X A mixture of 0% by weight of the cellulose triacetate of Example I and 50% by Weight of polyhexamethylene adipamide was dissolved in dichloroacetic acid to give a 4 solution of 10% by weight of total polymeric material having a Brookfield viscosity at 22 C. of 1700 poises. Satisfactory films of the mixed polymeric material could be obtained by coagulating the dope in hot water.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my invention what I desire to secure by Letters Patent is:

l. A solution of a cellulose carboxylic acid ester in a solvent consisting essentially of a compound selected from the group consisting of straight chain, lower aliphatic carboxylic acids and esters of said acids, said acids and esters containing at least one member of the group consisting of halide, sulfide, and ethylenically unsaturated radicals, and halogen-substituted lower carboxylic acid nitriles.

2. A solution of a cellulose acetate in a solvent consisting essentially of a compound selected from the group consisting of straight chain, lower aliphatic carboxylic acids and esters of said acids, said acids and esters containing at least one member of the group consisting of halide, sulfide, and ethylenically unsaturated radicals, and halogen-substituted lower carboxylic acid nitriles.

3. A solution of a cellulose acetate in a solvent consisting essentially of a halogen-substituted, straight chain, lower fatty acid.

4. A solution of a cellulose acetate in a solvent consisting essentially of an alkyl ester of halogen-substituted, straight chain, lower fatty acid.

5. A solution of a cellulose acetate in a solvent consisting essentially of a haloalkyl ester of a straight chain, lower fatty acid.

6. A solution of a cellulose acetate in a solvent consisting essentially of a halogen-substituted, straight chain, lower fatty acid nitrile.

7. A solution of a cellulose acetate in a solvent consisting essentially of a mercapto-substituted, straight chain, lower fatty acid.

8. A solution of a cellulose acetate in a solvent consisting essentially of a straight chain, aliphatic alkenyl carboxylic acid containing up to four carbon atoms.

9. A solution of cellulose acetate according to claim 3 containing a high molecular weight linear polyester of a polyhydric alcohol and a polycarboxylie acid, said polyester being present in an amount of 1 to percent by weight of the weight of the total polymeric material.

10. A solution of cellulose acetate according to claim 3 containing a high molecular weight linear polycarbonamide present in an amount of 1 to 80 percent by weight of the weight of the total polymeric material.

11. A method of forming fibers and films of a cellulose acetate which comprises dissolving said cellulose acetate in a solvent consisting essentially of a compound from the group consisting of a straight chain, lower aliphatic carboxylic acids and esters of said acids, said acids and esters containing at least one member of the group consisting of halide, sulfide and ethylenically unsaturated radicals, and halogen-substituted lower carboxylic acid nitriles, and separating most of said solvent from said solution in a form having a cross-section with at least one thin dimension.

12. A method according to claim 11 wherein the solvent consists essentially of a halogen-substituted, straight chain, lower fatty acid, and the solution further contains a high molecular weight linear polyester of a polyhydric alcohol and a polycarboxylic acid.

13. A method according to claim 11 wherein the solvent consists essentially of a halogen-substituted, straight chain, lower fatty acid, and the solution further contains a high molecular weight linear polycarbonamide.

14. A method of forming fibers of a cellulose acetate which comprises dissolving said cellulose acetate in a solvent consisting essentially of a compound from the group consisting of a straight chain, lower aliphatic carboxylic acids and esters of said acids, said acids and esters containing at least one member of the group consisting of halide, sulfide and ethylenically unsaturated radicals, and halogen-substituted, lower carboxylic acid nitriles, and extruding the resulting solution in the shape of filaments into a liquid medium which is a non-solvent for said cellulose acetate.

15. A solution of cellulose triacetate having an acetyl value above 59% by weight calculated as combined acetic acid in a solvent consisting essentially of a compound selected from the group consisting of straight chain, lower aliphatic carboxylic acids and esters of said acids, said acids and esters containing at least one member of the group consisting of halide, sulfide, and ethylenically unsaturated radicals, and halogen-substituted, [lower carboxylic acid nitriles.

16. A solution according to claim 3 wherein said acid is beta-chloropropionic acid and said acid is mixed with water.

References Cited in the file of this patent UNITED STATES PATENTS 2,336,310 Spence et a1. Dec. 7, 1943 2,346,350 Berl et a1. Apr. 11, 1944 2,350,300 Bogin May 30, 1944 2,362,182 Baker Nov. 7, 1944 2,542,402 Easton Feb. 20, 1951 2,607,703 Resch et a1. Aug. 19, 1952 2,812,267 Garner et a1. Nov. 5, 1957 2,902,383 Beste Sept. 1, 1959 OTHER REFERENCES Ott et a1.: High Polymers, vol. V, part II (1954), pages 794 and 795.

Ott et al.: High Polymers, Vol V, part III (1955), pages 1454-1456.

Brice et al.: Chem. and Eng. News, vol. 3 (1953), pages 20 510-513 (TP 1 I 418).

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2336310 *Jan 7, 1941Dec 7, 1943Eastman Kodak CoMethod of preparing flexible cellulose triacetate materials
US2346350 *Apr 2, 1941Apr 11, 1944Ernst BerlHighly substituted acetone-soluble cellulose acetate
US2350300 *Apr 24, 1943May 30, 1944Commercial Solvents CorpCellulose triacetate composition
US2362182 *Dec 20, 1941Nov 7, 1944Bell Telephone Labor IncManufacture of cellulose acetate solutions
US2542402 *Nov 7, 1946Feb 20, 1951Gen Aniline & Film CorpSolutions of cellulose triacetate
US2607703 *Nov 23, 1949Aug 19, 1952Eastman Kodak CoPreparation of acetic acid solutions of cellulose acetate
US2812267 *Mar 31, 1954Nov 5, 1957Shell DevResinous compositions plasticized with esters of sulfur-containing alcohols
US2902383 *Sep 25, 1957Sep 1, 1959Du PontCellulose triacetate composition
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3673084 *Jul 14, 1969Jun 27, 1972Aerojet General CoReverse osmosis and process and composition for manufacturing cellulose acetate membranes wherein the swelling agent is a di-or tri-basic aliphatic acid
US4536240 *Feb 22, 1983Aug 20, 1985Advanced Semiconductor Products, Inc.Dispensing polymer/solvent mixture onto rotational support, and ap
Classifications
U.S. Classification106/170.26, 106/170.37, 106/170.27, 524/37, 106/311, 252/364, 106/18.2, 106/18.23, 106/18, 524/41
International ClassificationD01F2/28
Cooperative ClassificationD01F2/28
European ClassificationD01F2/28