US3003984A

US3003984A - Solution of polypyrrolidone in a mixture of 1,1,1-trichloro-3-nitro-2-propanol and water and process of making same

Info

Publication number: US3003984A
Application number: US816067A
Authority: US
Inventors: William B Black
Original assignee: Chemstrand Corp
Current assignee: Solutia Inc
Priority date: 1959-05-27
Filing date: 1959-05-27
Publication date: 1961-10-10
Anticipated expiration: 1978-10-10

Description

l st.

A u. i Ii 1 United States Patent Ofifice 3,003,984 Patented Oct. 10, 1961 3 003 84 SOLUTION OF POLYlYliROLIDONE IN A MIX- TURE OF 1,1,1-TRICHLORO-3-NITRO-2-PROPA- gIOL AND WATER AND PROCESS OF MAKHIG William B. Black, Decatur, Ala, assignor to The Chemstrand Corporation, Decatur, Ala., a corporation of Delaware No Drawing. Filed May 27, 1959, Ser. No. 816,067

14 Claims. (Cl. 260-492) which make it desirable for utilization in the manufacture of end products, such as ribbons, films, fibers, filaments, rods, bristles, lacquers, coatings, shaped articles and the like. Polypyrrolidone can be converted into shaped articles in many ways. For example, it may be cast into films or forced through multi-hole spinnerets to form fibers or filaments. Regardless of the end use to which the polypyrrolidone is to be put, it is generally more convenient and efficient to employ the polymer in a solution. This is well illustrated in the textile industry where polypyrrolidone is employed in the formation of fibers and filaments, which are manufactured by several methods of spinning, such as melt spinning, dry spinning and wet spinning.

In the melt spinning method, the polymer is heated to a high temperature until it becomes molten, and is thereafter forced through sand packs and the like, and thence through a spinnert from whence it is extruded in filamentary form. This method has, however, many disadvantages, although it is widely used in the industry at the present time in the production of synthetic fibers and filaments. The high temperatures used in molt spinning require the exercise of extreme care in order to prevent the decomposition of the polymer. Furthermore, the high temperatures also affect the chemical and physical characteristics of the polymer and thereby result in a product of inferior quality. In addition to these disadvantages, it is extremely ditficult to add to the molten polymer at such high temperatures compounds such as dyes, antistatic agents, plasticizers and the like.

In the dry-spinning method of fiber formation, the polymer is dissolved in a suitable solvent and subsequently extruded from spinnerets into a heated atmosphere in order to evaporate the polymer.

In order to form filaments by the wet spinning method, the polymer is dissolved in a suitable solvent and extruded from a spinneret into a coagulating bath capable of leachthe solvent from the fibers. Normally, this method may be carried out at temperatures much lower than either the melt spinning or dry spinning methods. If it is desired to use additives, such as dyes, anti-static agents, fireretarding agents, plasticizers and the like, in the polymeric solution, they may be incorporated therein without the danger of decomposition or seriously affecting the properties of the end product where the wet spinning method of filament formation is employed. It is much easier to introduce such additives into a solution than to introduce them into a molten composition. Then again, solutions are much easier to handle during processing, and in many cases may be stored for long periods of time Without a change of physical and chemical properties. It is much easier to cast a film from a solution than to cast it from a molten composition. It is readily apparent, therefore, that solutions of polypyrrolidone possess many distinct advantages over molten compositions in the manufacture of end products.

invention to provide solutions of polypyrrolidone. It is a further object of the invention to provide solutions of polypyrrolidone which may be converted into shaped articles, such as ribbons, films, filaments, rods, fibers, bristles, and the like. It is still another object of the invention to provide a process for the preparation of polypyrrolidone solutions. Other objects and advantages of the instant invention will be readily apparent from the description thereof which follows hereafter.

In general, the objects of the present invention are accomplished by dissolving polypyrrolidone in 1,1,l-trichloro-3-nitro-2-propanol or 1,1,l-trichloro-3-nitro-2-propanol containing a minor amount of water.

When employing water in conjunction with 1,1,1-trichloro-3-nitro-2-propanol in the practice of the present invention, the water may be utilized in a range of about 0.5 to 10 percent, based on the total weight of the solvent or in any amount suflicient to make a saturated solution. The water is advantageous in that it permits the preparation of solutions at room temperature since the 1,1,l-trichloro-3-nitro-2-propanol which is a solid at room temperature readily liquifies when mixed with minor amounts of water, since the addition of water thereto lowers the melting point of l,l,1-trichloro-3-nitro-2-propanol. Water is further advantageous in that it regulates the viscosity of the polymer solution, thereby permitting the preparation of relatively low viscosity solutions which are extremely easy to handle when they are to be used for specific end uses such as, for example, the preparation of films or coatings.

It will be readily apparent to those skilled in the art that polypyrrolidone can be dissolved in the solvents of the present invention in widely varying concentrations. The concentration of any particular polymer in any particular solvent depends upon the nature of the polymer, the solvent employed and the temperature, which in turn effect the viscosity of the solution. Normally, when the solution is to be employed in the manufacture of fibers and filaments, as much as 30 percent of the polymer, based on the total weight of the solution, may be dissolved in the solvents of this invention. While it is preferred to employ 10 to 25 percent of the polymer, based on the total Weight of the solution, when the solution is to be used in the preparation of fibers and filaments, it is to be understood that as little as 5 percent or less and more than 30 percent of polypyrrolidone may be dissolved in the solvents of this invention when the solution is to be used for other purposes, such as coating or a lacquer and the like, or when lower or higher molecular Weight polypyrrolidones are dissolved inthe solvents.

The solvents of this invention readily dissolve polypyrrolidone within a wide range of temperature depending on the nature of the polymer, the concentration thereof in the solvent and the nature of the solvent itself. Although temperatures within a range of 25 C. to C. are preferred as a practical matter in bringing about solution, temperatures as low as the freezing point of the solvent and as high as the boiling point of the polymer/ solvent mixture may be employed to bring about solution. Heating of the polymer/ solvent mixture is preferably accomplished on a water, glycerine or oil bath. However, other means may be employed. If desired, agitation or stirring of the mixture may be employed during heating while a solution is being formed at low temperatures, although it is to be understood that it is not always necessary or critical.

If it is desired to produce shaped articles from the polypyrrolidone compositions of the present invention which have a modified appearance and modified properties, various agents to accomplish these effects may be added to the polymer solution prior to fabrication of the articles without having any ill effects thereon. Such agents may be plasticizers, pigments, dyes, antistatic agents, fire-retarding agents, and the like.

Polypyrrolidone soluble in the solvents of this invention may be prepared by various processes. Generally, however, polymeric pyrrolidone is prepared by polymerizing 2-pyrrolidone in the presence of a catalyst or a catalyst and activator at a temperature in a range of 70 C. to 100 C. However, since the polymerization reaction proceeds well in a range of 20 C. to 70 C., these temperatures are preferred in carrying out a polymerization procedure.

In the preparation of polypyrrolidone, a large number of known catalysts are available to catalyze the polymerization. Among such catalysts, there may be named the alkali metals, namely, sodium, potassium and lithium, as well as the hydrides, hydroxides, oxides and sflts of the alkali metals, that is, such salts as sodium, lithium and potassium pyrrolidone. Organic metallic compounds, preferably those which are strongly basic, may be used as catalysts, too. Examples of such compounds are lithium, potassium and sodium alkyls and aryls of the alkali metals, such as sodium phenyl. Another suitable catalysts is sodium amide. The alkali hydrides, however, are the preferred catalysts since a distinct advantage is obtained by their use. Sodium hydride, for example, does not react in the polymerization mixture to form water, which, as is well known, has a deleterious effect on pyrrolidone polymerization. Where water-forming catalysts, such as sodium hydroxide, are employed as a catalyst, all water of reaction must be removed from the reaction mixture by vacuum distillation or other means in order for polymerization to proceed at a reasonable rate. Generally, the catalysts may be employed in a range of 0.002 to 0.25 chemical equivalent based upon one mole of monomeric pyrrolidone in carrying out a polymerization reaction.

Although polypyrrolidone having acceptable properties can be prepared by using a catalyst alone, it is preferable to employ an activator in conjunction with any of the catalysts mentioned above, since the polymer prepared in the presence of both a catalyst and activator has greatly improved properties over polypyrrolidone prepared in the presence of a catalyst alone. Among the compounds which may be employed as activators, there may be named the acyl compounds, such as acetyl pyrrolidone, acetyl morpholone, and the like; lactones, such as gamma butyrolactone, and the like; alkyl esters of monoand dicarboxylic acids, such as ethyl acetate, ethyl oxalate, and the like; the esters of polyhydric alcohols, such as ethylene glycol diacetate and the like; and nitrogen dioxide and organic nitrites having the general formula:

wherein R is selected from the group consisting of alkyl groups containing 1 to carbon atoms, haloalkyl groups containing 2 to 10 carbon atoms, nitroalkyl groups containing 2 to 10 carbon atoms, aralkyl groups containing 7 to 10 carbon atoms, and alkoxyalkyl groups containing 3 to 12 carbon atoms. Among the nitrites falling into the general formula set out above, there are methyl nitrite, ethyl nitrite, n-propyl nitrite, iso-propyl nitrite, n-butyl nitrite, iso-butyl nitrite, amyl nitrite, iso-amyl nitrite, hexyl nitrite, heptyl nitrite, octyl nitrite, nonyl nitrite, decyl nitrite, and their isomeric forms, and the like; haloalkyl nitrites, such as 2,2,2-trichloroethyl nitrite; the dihaloalkyl nitrites, such as 2,2-dichloroethyl nitrite, 2,2-dichloropropyl nitrite, 2,2-dichlorobutyl nitrite, 2,2-dichloroamyl nitrite, 2,2-dichlorohexyl nitrite, 2,2-dichloroheptyl nitrite, 2,2-dichlorooctyl nitrite, 2,2-dichloronoyl nitrite, 2,2-dichlorodecyl nitrite, and the like monochloroalkyl nitrites, their isomeric forms, and the like; nitroalkyl nitrites, such as Z-nitroethyl nitrite, 2-nitropropyl nitrite, Z-nitrobutyl nitrite, 2-nitroamyl nitrite, 2-nitrohexyl nitrite, 2-nitroheptyl nitrite, 2-nitroocty1 nitrite, 2- nitromonyl nitrite, Z-nitrodecyl nitrite, and their isomeric forms, and the like; aralkyl nitrites, such as benzyl nitrite, Z-methyl'oenezyl nitrite, 3-methylbenzyl nitrite, 4-methylbenzyl nitrite, 2-ethylbenzyl nitrite, 3-ethylbenzyl nitrite, 4-ethylbenzyl nitrite, Z-propylbenzyl nitrite, 3-propylbenzyl ntirite, 4-propylbenzyl nitrite, 2-methyl-3-ethylbenzyl nitrite, 2-methyl-4-ethylbenzyl nitrite, 2-methyl-5-ethylbenzyl nitrite, 2-methyl-6-ethylbenzyl nitrite, 3-methyl-4- ethylbenzyl nitrite, 3-rnethyl-5-ethylbenzyl nitrite, 3-methyl-6-ethylbenzyl nitrite, 4-methyl-2-ethylbenzyl nitrite, 4- methyl-3-ethylbenzyl nitrite, 2,3-dimethylbenzyl nitrite, 2,4-dimethylbenzyl nitrite, 2,5-dimethylbenzyl nitrite, 2,6- dimethylbenzyl nitrite, 3,4-dimethylbenzyl nitrite, 3,5- dimethylbenzyl nitrite, and the like; and alkoxyalkyl nitrites, such as Z-methoxyethyl nitrite, 2-ethoxyethyl nitrite, Z-propoxyethyl nitrite, 2-butoxyethyl nitrite, 2-pentoxyethyl nitrite, Z-hexoxyethyl nitrite, Z-heptoxyethyl nitrite, 2-octoxyethyl nitrite, Z-nonoxyethyl nitrite, Z-decoxyethyl nitrite, and their isomeric forms and the like.

Another excellent polymerization activator is carbon disulfide. Silicon halides and organic silicon halides having the general formula:

wherein R is a saturated or unsaturated aliphatic or aromatic hydrocarbon radical containing 1 to 10 carbon atoms, a saturated or unsaturated aliphatic or aromatic halogenated hydrocarbon radical containing 1 to 18 carbon atoms, and X is a halogen, z is an integer from 1 to 4 inclusive, and y is equal to 4-z, wherein R may be similar or dissimilar radicals, may also be employed to activate polymerization of Z-pyrrolidone. Among the silicon halides and organic silicon halides there may be named tetrachlorosilane, alpha, beta-dichloroethyltrichlorosilane, bis (chloromethyl) methylchlorosilane, butyltrichlorosilane, chloromethylmethyldichlorosilane, dichloromethyldimethylchlorosilane, diethyldichlorosilane, dimethyldichlorosilane, diphenyldichlorosilane, ethyltrichlorosilane, methyltrichlorosilane, phenyltrichlorosilane, propyltrichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, the iodoand bromoforms of the above compounds, and many others. The trihalides of phosphorous, aluminum, bismuth and antimony, the tetrahalides of titanium, tin, zirconium and lead, and the pentahalides of antimony and phosphorous are also useful as activators in the polymerization of 2-pyrrolidone. Such compounds include aluminum trichloride, aluminum tribromide, aluminum triiodide, stannic tetrachloride, stannic tetrabromide, lead tetrachloride, zirconium tetrachloride, bismuth trichloride, bismuth tribromide, antimony trichloride, antimony tribromide, antimony triiodide, antimony pentaehloride, antimony pentaiodide, antimony pentafluoride, and the like. The phosphorous halides include phosphorous tribromide, phosphorous pentabromide, phosphorous trichloride, phosphorous pentaehloride, phosphorous trifluoride, phosphorous pentafluoride, phosphorous triiodide, and the like. Generally, in the preparation of polypyrrolidone wherein both a catalyst and activator are employed to bring about polymerization, the activator is utilized in a range of 0.0001 to 0.075 chemical equivalent of activator, based upon one mole of 2- pyrrolidone.

The polypyrrolidone soluble in the solvents of the invention is prepared by simple polymerization methods. It can be prepared readily by well-known solution, emulsion, suspension or bulk polymerization procedures. The solution and emulsion polymerizations may be either batch, semi-continuous or continuous methods. When solution polymerization is employed, the monomer is dissolved in a solvent such as 1,4-dioxane, the desired catalyst or activator, or both, added to the solution, and

the polymerization carried out under the proper conditions. Well-known solution polymerization apparatus is suitable for preparing the polypyrrolidone described herein. Where either emulsion or suspension polymeri zation techniques are employed to prepare the polymer, the monomer containing the catalyst is dispersed in a non-solvent, such as petroleum ether, and an emulsifying agent, then added to the dispersion. Subsequently, the desired activator is injected into the mixture and the dispersion is polymerized until the reaction is complete. At this time, suitable coagulant is added to the polymerization mixture in order to precipitate the polymer. A suitable emulsifying agent is sodium lauryl sulfate, and the suitable coagulant is phosphoric acid.

Polypyrrolidone prepared in accordance with the procedures set forth hereinabove has a melting point of about 260 C. and a specific viscosity of from about 0.3 to 4.5 or more. It is thus particularly adapted for the manufacture of shaped articles such as filaments, fibers, films, nods, bristles, and the like. Lower molecular weight polymers prepared in the same manner are suitable for the preparation of coatings or lacquers.

The following examples are intended to illustrate the new compositions of this invention more fully but are not intended to limit the scope of the invention, for it is possible to efiect many modifications therein. In the examples, all parts and percents are by weight unless otherwise indicated.

Example I To 100 grams of essential anhydrous 2-pyrrolidone, there was added under a nitrogen atmosphere 1.0 gram of sodium hydride catalyst. When the evolution of hydrogen gas was completed, this mixture was stoppered to protect it against the atmosphere and permitted to stand at about 35 C. for 15 hours. The polymer was recovered by breaking up the resultant cake, grinding it with water in a Waring Blendor. The polymer was then filtered, washed with acetone and air-dried to constant weight. There was obtained a yield of 30.7 grams of polymer, approximately 30.7 percent of the theoretical yield. The polymer had a specific viscosity of 0.882 (determined on 0.5 percent solutions of the polymer in 90 percent formic acid at 25 C.).

1.5 grams of the polypyrrolidone so prepared were mixed with 3.5 grams of a solvent containing 1,1,1-trichloro-3-nitro-2-propanol and percent water, based on the total weight of the solvent. The mixture was stirred with heating to 145 C. where the polymer readily dissolved to give an extremely viscous, translucent solution containing 30 percent polymer. 'On cooling, the polymer precipitated out of the solution at 135 C. The solution so formed was suitable for the formation of fibers or filaments by the wet or dry methods of spinning or forming a coating.

Example II 0.5 gram of the polypyrrolidone prepared in accordance with the procedure of Example I and 9.5 grams of the solvent of Example I were mixed together and heated with stirring to 36 C. to give a clear viscous solution which was completely stable at room temperature (25 C.). The solution was suitable for casting films and making coatings.

Example III 0.5 gram of the polypyrrolidone used in Example I and 4.5 grams of a mixed solvent containing 1,1,1-trichloro-3-nitro-2-propanol and 1 percent water, based on the total weight of the solvent, were mixed together and heated with stirring to 45 C. to give a clear, viscous solution containing 10 percent polymer. The solution was completely stable at room temperature (25 C.) and suitable for the spinning of fibers and filaments by either the wet or dry spinning methods.

Example IV To a 150 gram sample of essentially anhydrous 2- pyrrolidone, there was added under a nitrogen atmosphere sodium hydride catalyst in a ratio of 1:100 parts catalyst to monomer. When the evolution of hydrogen gas was completed, this mixture was stoppered to protect it against the atmosphere and permitted to stand at about 25 C. for 5 days. The polymer was recovered by breaking up the cake, grinding it in a Wiley mill, and washing the powder, first with water, then with acetone, in a Waring Blendor. The polymer was subsequently air-dried to constant weight and had a specific viscosity of 0.489 (determined on 0.5 percent solutions of the polymer in 90 percent formic acid at 25 C.).

0.5 gram of the polypyrrolidone so prepared was mixed with 2.0 grams of l,1,1-trichloro-3-nitro-2-propanol. The mixture was stirred with heating to 80 C. where the polymer readily dissolved to give a clear, very viscous solution of 20 percent polymer. The solution was stable at room temperature (25 C.) overnight and was suitable for the spinning of fibers and filaments by either the wet or dry spinning methods.

Example V To a 50 gram sample of essentially anhydrous 2-pyrrolidone, there was added under a nitrogen atmosphere 0.5 gram of sodium hydride catalyst. When the evolution of hydrogen gas was completed, there was added 0.448 gram of carbon disulfide activator. The reaction mixture was stirred vigorously and stoppered to protect it against the atmosphere. It was permitted'to stand at about'25 C. for four hours. The resultant polymer cake was then ground up with water in a Waring Blendor and the polymer filtered. The filter cake was washed with acetone and subsequently air-dried to constant weight. The polymer had a specific viscosity of 0.471 (determined on 0.5 percent solutions of the polymer in percent formic acid at 25 C.).

0.5 gram of the polypyrrolidone so prepared was added to 2.0 grams of a mixed solvent containing 1,1,1-trichloro- 3-nitro-2-propanol saturated with water (approximately 10 percent water, based on the total weight of the solvent). The mixture was stirred with heating to 79 C. where the polymer readily dissolved to give a clear, slightly viscous solution containing 20 percent polymer. Onpcooling to room temperature (25 C.), the solution remained stable. The solution so formed was suitable for the spinning of films and fibers by either the wet spinning or dry spinning methods.

This solution was much less viscous than that in the foregoing example where no water was present, although the polymers had approximately the same specific viscosity.

Polypyrrolidone prepared with other catalysts and activators and having varying molecular weights and viscosity values gave like results when dissolved in the new solvents of this invention.

The new compositions of this invention present many advantages. For example, solutions of polypyrrolidone may be easily prepared on existing equipment without detailed and elaborate procedures. The l,l,l-trichloro-3- nitro-2-propanol which is employed as a solvent herein is readily available and reasonably inexpensive. When water is used with the 1,1,l-trichloro-3-nitro-2-propanol in a mixed solvent, numerous other advantages are attained. For example, solutions containing a higher concentration of polymer can be prepared where water is employed in the mixed solvent. Furthermore, use of water reduces the viscosity of a given concentration of polymer in any particular solvent mixture. In addition, use of water results in a less expensive solvent. Another important advantage in using a mixture of water and 1,1,1-trichloro-3-nitro-2-propanol to dissolve polypyrrolidones such as those described hereinabove is that the water permits the preparation of solutions at temperatures lower than the melting point of 1,1,1-trichloro-3-nitro-2- propanol which is 42 C. Numerous other advantages of the compositions of this invention will be readily apparent to those skilled in the art.

It will be understood to those skilled in the art that many apparently widely difierent embodiments of this invention can be made without departing from the spirit and scope thereof. Accordingly, it is to be understood that this invention is not to be limited to the specific embodiments thereof except as defined in the appended claims.

I claim:

1. A new composition of matter comprising polypyrrolidone and a solvent selected from the group consisting of 1,1,1-trichloro-3-nitro-2-propanol and mixtures of 1,1, 1-trichloro3-nitro-2-propanol with from 0.5 percent up to a saturating amount of water, based on the total weight of the solvent.

2. A new composition of matter as defined in claim 1 wherein the solvent is 1,l,1-trichloro-3-nitro-2-propanol.

3. A new composition of matter as defined in claim 1 wherein the solution contains 1,1,1-trichloro-3-nitro-2- propanol and water.

4. A new composition of matter comprising 5 to 30 percent, based on the total weight of the composition, of polypyrrolidone and a solvent selected from the group consisting of 1,1,1-trichloro-3-nitro-2-propanol and mixtures of 1,1,1-trichloro-3-nitro-2-propanol with from 0.5 percent up to a saturating amount of water, based on the total weight of the solvent.

5. A new fiber-forming composition of matter comprising to 25 percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of at least 0.3, and a solvent selected from the group consisting of 1,1,1-trichloro-3-nitro-2-propanol and mixtures of 1,1,l-t1ichloro-3-nitro2-propanol with from 0.5 percent up to a saturating amount of water, based on the total weight of the solvent.

6. A new composition of matter comprising 5 percent, based on the total weight of the composition, of polypyrrolidone and a mixture of 1,1,1-trichloro-3-nitro-2- propanol and 10 percent water, based on the total weight of the solvent.

7. A new fiber-forming composition of matter comprising percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of 0.471 and a solvent containing 1,1,1-trichloro-3-nitro-2- propanol and 10.0 percent water, based on the total weight of the solvent.

8. A process for preparing a new composition of matter comprising mixing polypyrrolidone and a solvent selected from the group consisting of 1,1,1-trichloro-3- nitro-2-propanol and mixtures of 1,1,l-trichloro-3-nitro-2- propanol with from 0.5 percent up to a saturating amount of Water, based on the total weight of the solvent, and

dissolving the mixture at a temperature in a range of the freezing point of the solvent and the boiling point of the mixture to form a homogeneous solution.

9. The process as defined in claim 8 wherein the solvent is 1,1,1-trichloro-3-nitro-2-propanol.

10. The process as defined in claim 8 wherein the solution contains 1,1,1-trichloro-3-nitro-2-propanol and water.

11. A process for preparing a new composition of matter comprising mixing 5 to 30 percent, based on the total weight of the composition, of polypyrrolidone and a solvent selected from the group consisting of 1,1,1-trichloro-3-nitro-2-propanol and mixtures of 1,1,1-trichloro- 3-nitro-2-propanol with from 0.5 percent up to a saturating amount of water, based on the total weight of the solvent, and heating the mixture to a temperature in a range of 25 C. to the boiling point of the mixture to form a homogeneous solution.

12. A process for preparing a new fiber-forming composition of matter comprising mixing 10 to 25 percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of at least 0.3, and a solvent selected from the group consisting of 1,1,1- trichloro-3-nitro-2-propanol and mixtures of 1,l,1-trichloro-3-nitro-2-propanol with from 0.5 percent up to a saturating amount of water, based on the total weight of the solvent, and heating the mixture to a temperature in a range of 25 C. to the boiling point of the mixture to form a homogeneous solution.

13. A process for preparing a new fiber-forming composition of matter comprising mixing 20 percent, based on the total weight of the composition, of polypyrrolidone, having a specific viscosity of 0.489, and 1,1,1-trichloro- 3-nitro-2-propanol, and heating the mixture to a temperature of C. to form a homogeneous solution.

14. A process for preparing a new fiber-forming composition of matter comprising mixing 20 percent, based on the total weight of the solution, of polypyrrolidone, having a specific viscosity of 0.471, and a solvent containing percent l,l,1-trich1oro-3-nitro-2-propanol and 10 percent water, based on the total weight of the solvent, and heating the mixture to a temperature of 79 C. to form a homogeneous solution.

References Cited in the file of this patent UNITED STATES PATENTS 2,377,985 Watkins June 12, 1945 2,732,359 De Witt Jan. 24, 1956 2,861,969 De Witt Nov. 25, 1958 FOREIGN PATENTS 205,015 Australia Nov. 11, 1954 218,129 Australia Jan. 16, 1958

Claims

1. A NEW COMPOSITION OF MATTER COMPRISING POLYPYRROLIDONE AND A SOLVENT SELECTED FROM THE GROUP CONSISTING OF 1,1,1-TRICHLORO-3-NITRO-2-PROPANOL AND MIXTURES OF 1,1, 1-TRICHLORO-3-NITRO-2-PROPANOL WITH FROM 0.5 PERCENT UP TO A SATURATING AMOUNT OF WATER, BASED ON THE TOTAL WEIGHT OF THE SOLVENT.