JP2003268624A - Spinning dope and wet spinning method using the dope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spinning dope having decreased viscosity to improve the material handling of an acetone solution of an acrylic polymer derived from acrylonitrile, vinyl chloride and a vinyl monomer containing sulfonic acid group, and provide a wet-spinning method using the spinning dope having decreased viscosity. <P>SOLUTION: An acetone solution of the acrylic polymer obtained from the acrylonitrile, vinyl chloride and the vinyl monomer containing sulfonic acid group is incorporated with a sulfonic acid compound different from that of the acrylic polymer to obtain the spinning dope. The wet spinning is carried out by using the dope. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to reducing the viscosity of a spinning dope prepared by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and a vinyl monomer having a sulfonic acid group as a main component in acetone. How to make
The present invention also relates to a spinning dope and a wet spinning method using the same.

[0002]

2. Description of the Related Art A spinning stock solution prepared by dissolving an acrylic copolymer obtained by copolymerizing acrylonitrile, vinyl chloride and a vinyl monomer containing a sulfonic acid group as a main component in acetone is dissolved in dimethylformamide or dimethylsulfoxide. It is recognized that the structural viscosity is stronger than that of the spinning dope. After understanding this characteristic, conventionally, wet spinning is carried out by adjusting the viscosity by setting a stock solution concentration suitable for existing spinning equipment, that is, a stock solution concentration that does not hinder material handling. On the other hand, in such wet spinning, it is generally known that the higher the polymer concentration in the spinning dope, the more dense the coagulation structure during spinning and the more favorable the values of various physical properties. Therefore, in wet spinning, it is preferable that the concentration of the polymer in the spinning dope is as high as possible so long as it does not hinder material handling.

By the way, the conventional acrylic fiber obtained by spinning the acrylic copolymer is not sufficiently satisfactory in dyeability, and there has been a demand for improvement in dyeability for some time. As a countermeasure, attempts have been made to increase the copolymerization ratio of the sulfonic acid group-containing vinyl monomer serving as the dyeing seat. However, when the copolymerization ratio of such a sulfonic acid group-containing vinyl monomer is increased, the viscosity of the spinning stock solution in which the copolymer is dissolved in acetone becomes high, so the polymer concentration of the spinning stock solution is unavoidably reduced to perform spinning. There is a need.
As a result, the liquid content of the gel-like fiber in the spinning step becomes high and the structure of the gel-like fiber after coagulation becomes rough, resulting in brittleness of the fiber strength, causing troubles in production, and for practical production. Has a limit in the copolymerization ratio of the sulfonic acid group-containing vinyl monomer.

Therefore, the prior art was investigated from the viewpoint of reducing the viscosity of the spinning dope. Regarding the spinning technology, as shown in, for example, JP-A-7-41597 and JP-A-8-157596, spinning during melt spinning was performed. Although many studies have been made on the technique for reducing the viscosity of the undiluted solution, the technique for wet spinning, particularly, the method for reducing the viscosity of the undiluted solution in spinning when spinning the acetone solution of the acrylic copolymer has not been examined, and the technique has not been established.
The current situation is that it is not generally known.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to improve a material handling by acrylonitrile,
It is intended to provide a method for reducing the viscosity of a spinning dope prepared by dissolving an acrylic copolymer obtained from vinyl chloride and a vinyl monomer having a sulfonic acid group in acetone, and the spinning dope.

[0006]

Means for Solving the Problems The present inventor has hitherto paid attention to the phenomenon that the viscosity of an acetone solution of an acrylic copolymer increases in order to increase the copolymerization ratio of a vinyl monomer containing a sulfonic acid group. As a result of the investigation, it was found that the involvement of the sulfonic acid group is large in relation to the structural viscosity, and further, by the presence of the sulfonic acid group not bound to the copolymer, it was found that the viscosity of the spinning dope can be reduced,
The present invention has been completed.

That is, according to the present invention, an acrylic copolymer obtained by polymerizing acrylonitrile, vinyl chloride and a vinyl monomer having a sulfonic acid group as a main component, and a sulfonic acid compound which is not copolymerized with these monomers, It relates to a spinning stock solution dissolved in acetone.

In a preferred embodiment thereof, the above-mentioned spinning stock solution in which the composition ratio of the sulfonic acid group-containing vinyl monomer in the acrylic copolymer is 1 to 3% by weight, or the sulfonic acid compound is toluenesulfonic acid. The present invention relates to the spinning dope.

The present invention also relates to a wet spinning method for an acrylic copolymer, characterized by wet spinning the above spinning dope.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic copolymer of the present invention is obtained by copolymerizing a mixture of acrylonitrile, vinyl chloride and a monomer containing a vinyl monomer having a sulfonic acid group as a main component. . Acrylonitrile is usually 30 to 55% by weight, preferably 40 to 53% by weight, more preferably 45 to 52% by weight, and vinyl chloride is usually 44 to 69 in the acrylic copolymer. %, Preferably 46 to 59% by weight, more preferably 47 to 54% by weight, and the sulfonic acid group-containing vinyl monomer is usually 1 to 3% by weight, preferably 1.2.
~ 2.7 wt%, more preferably 1.5-2.5 wt%
Is. Further, the acrylic copolymer of the present invention may have a composition in which one or more vinyl monomers are further copolymerized, and other copolymers and other copolymers soluble in the solvent of the copolymer may be used. It may be a mixed composition with the coalescence. When the copolymerization amount of acrylonitrile is less than 30% by weight, the wool-like texture that is characteristic of acrylic fibers cannot be obtained when formed into fibers, and when it exceeds 55%, the solubility of the polymer in acetone which is a solvent is high. Is required, a special device of high temperature and high pressure is required, and it is not suitable as a spinning stock solution because it is difficult to handle.

The sulfonic acid group-containing vinyl monomer in the present invention is not particularly limited as long as it is a sulfonic acid group-containing vinyl monomer copolymerizable with acrylonitrile and vinyl chloride, but is not limited to methallyl sulfonic acid and allyl sulfone. Acid, isoprene sulfonic acid, styrene sulfonic acid, 2-
Representative examples thereof include acrylamido-2-methylpropanesulfonic acid, sulfophenylmethallyl ether, and their sodium, potassium, and ammonium salts. When the copolymerization ratio of these sulfonic acid group-containing vinyl monomers is less than 1%, a so-called normal dyeing agent may be used in combination with a cationic dye during dark color dyeing, or a long dyeing time may be required. In dyeing, the dissatisfaction which is inferior to that of commercial acrylic fibers remains, and when it exceeds 3%, the coagulability during spinning is insufficient, and as a result, there are many troubles in fiber production and it tends to be difficult to form fibers.

Other than the above, one or more copolymerizable vinyl monomers include lower alkyl esters of acrylic acid and methacrylic acid, N- or N, N-alkyl-substituted aminoalkyl esters and glycidyl esters, acrylamide and methacrylamide. Those N or N, N-alkyl-substituted products, carboxyl group-containing vinyl monomers represented by acrylic acid, methacrylic acid, itaconic acid and the like, and anionic vinyl monomers such as sodium, potassium or ammonium salts thereof, Cationic vinyl monomers such as quaternized aminoalkyl esters of acrylic acid and methacrylic acid, or vinyl group-containing lower alkyl ethers, vinyl group-containing lower carboxylic acid esters represented by vinyl acetate, vinyl bromide, blue Vinylidene bromide, vinylidene bromide and chloride Vinylidene and the like, but not limited to monomers.

In the present invention, the viscosity of the spinning dope can be reduced by adding a sulfonic acid compound that does not copolymerize with the above monomer to the spinning dope prepared by dissolving the acrylic copolymer in acetone. The sulfonic acid compound to be added may be any one as long as it has solubility in acetone, and examples thereof include aliphatic sulfonic acids, aromatic sulfonic acids and salts thereof, and toluene sulfonic acid is particularly preferable among aromatic compounds. Among the toluenesulfonic acids, p-toluenesulfonic acid is more preferable because it can be used more frequently than it is commercially available. The proportion of the sulfonic acid compound added to the spinning dope is 0.1 to 10 times mol, preferably 0.3 to 5 times mol, of the sulfonic acid group-containing vinyl monomer constituting the acrylic copolymer. ,
More preferably, it is 0.5 to 3 times mol. If it is less than 0.1 times by mole, the effect of viscosity reduction is small, and if it exceeds 10 times by mole, the viscosity reducing effect can be expected, but as a result of the progress of coloring of the polymer solution, the whiteness of the obtained fiber is lowered, It is not preferable because it is unsuitable for fiber applications requiring whiteness or light color dyeing. The sulfonic acid compound may be added directly or as a solution of water or acetone to a monomer mixture as a raw material before polymerization, or may be mixed and added to a copolymer after polymerization, or may be added to an acetone solution of the copolymer. The spinning stock solution of the present invention can be obtained by adding it.

For the present wet spinning, the spinning dope of the present invention is preferably adjusted to a value of 20 to 500 dPa · sec as measured by a rotational viscometer (B type viscometer) at 40 ° C. If the viscosity of the spinning dope is less than 20 dPa · sec, the spinning nozzle in the coagulation bath may not be properly set up, and the coagulated structure may become rough, resulting in poor continuity of the coagulated polymer and a decrease in the strength of the gel fiber. Becomes brittle, while 50
If it exceeds 0 dPa · sec, it will be difficult to remove the gas entrained during stirring and dissolution, and if the reduced pressure removal method is performed, acetone will also evaporate and it will be necessary to devise the concentration control, and the filtration pressure of the spinning dope will increase. It is not preferable because it may cause trouble. The spinning dope of the present invention prepared as a spinning dope is spun into fibers by an aqueous wet spinning method using a known acetone solvent. At this time, the acetone concentration of the coagulation bath is generally 0 to 50% by weight, and the temperature of 5 to 40 ° C is generally applicable.

In the present invention, the reason why the viscosity of the spinning dope is reduced by containing the sulfonic acid compound in the spinning dope is not clear, but it is considered that the following phenomenon is involved. In the acetone solution of the acrylic copolymer, the copolymerization ratio of the sulfonic acid group-containing vinyl monomer is 1
When it is more than 10% by weight, the viscosity tends to increase and 1.2% by weight
When it becomes the above, it becomes remarkable, and when it becomes 1.5% by weight or more, it becomes extremely remarkable. This means that the sulfonic acid group present in the copolymer molecule acts as an extremely weak pseudo-crosslink or an intermolecular interaction with another adjacent copolymer molecule due to a physical action such as van der Waals force. It is considered that the viscosity is increased as a result of an increase in apparent molecular weight and obstacles in the flow of molecules. The sulfonic acid group participates in the Cl contained in the copolymer.
A H atom bonded to the α-position carbon to which a group or a CN group is bonded, a sulfonic acid group directly adjacent thereto, or an indirect sulfonic acid group mediated by a solvent, acetone, can be considered. It is considered that the presence of the sulfonic acid group which is not bonded to the copolymer alleviates the action between the molecules of the copolymer, and as a result, the viscosity may be reduced.

Up to now, examples of utilizing a sulfonic acid compound in an acrylic polymer include JP-B-47-892, JP-A-51-147619 and JP-A-8-134715. The present invention relates to a technique of adding a sulfonic acid compound at the time of solution polymerization in a dimethylformamide solution for the purpose of preventing coloration of the combined solution and obtaining fibers having good whiteness. The technique of reducing the viscosity of the solution by adding a sulfonic acid compound was first discovered in the present invention.

[0017]

EXAMPLES The present invention will be further described below based on Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, all the percentages of chemical compositions used are% by weight. Further, the draw ratio in the fiber manufacturing process is a value obtained by rounding off the second decimal place, and the relaxation rate is expressed as a percentage with respect to the fiber length before the relaxation treatment. Prior to the description of the examples, sample adjustment and evaluation methods were carried out by the following methods.

(Undiluted solution viscosity): Single cylinder type rotational viscometer
It was measured using a Bismetron type VSA (Shibaura System Co., Ltd.).

Example 1 An acrylic copolymer composed of 50% acrylonitrile, 48.5% vinyl chloride, and 1.5% sodium styrenesulfonate was preliminarily mixed with sodium styrenesulfonate having the above copolymer composition. 1.
A 6-fold molar p-toluenesulfonic acid was added and mixed to dissolve in acetone to obtain a spinning dope. The copolymer concentration of the adjusted spinning dope was 27%, and the viscosity at 40 ° C was 450.
It showed dPa · sec. This spinning solution was passed through a spinning nozzle (pore diameter 0.20 mm, number of pores 200) at 25 ° C. and concentration 3
It was spun into a coagulation bath consisting of 5% acetone water. Then 25
The mixture was introduced into a bath composed of 70% acetone water at 0 ° C., stretched twice and further passed through a bath composed of 30% acetone water. Then, pass through a washing bath consisting of 40 ° C warm water and further draw 1.6 times in a hot water bath at 80 ° C.
It was dried at 0 ° C. Then, after stretching 2.3 times at the same temperature, a relaxation treatment of 12% was performed at 150 ° C. to obtain a fiber.
In the process from spinning stock solution preparation to spinning to finish the final fiber, various problems such as liquid sending ability of spinning stock solution, spouting of spinning nozzle, tow breakage in each bath including coagulation bath, winding around rollers, etc. There was no occurrence and the process was stable.

(Example 2) In the acetone solution of the same acrylic copolymer as in Example 1, instead of 1.6 times mol of p-toluenesulfonic acid of sodium styrenesulfonate which is the copolymer composition, , 0.3 times mol of dioctyl sulfosuccinate (sodium salt) was added,
The spinning dope was adjusted to a concentration of 27% as in Example 1. The viscosity of this spinning dope at 40 ° C. was 430 dPa · sec. This spinning dope was spun in the same manner as in Example 1 to obtain fibers. As a result, as in Example 1, the process was extremely stable.

Comparative Example 1 The acrylic copolymer used in Example 1 was dissolved in acetone to which p-toluenesulfonic acid was not added, and the concentration was adjusted to 27% in the same manner as in Example 1 for spinning. The stock solution was prepared, but the viscosity at 40 ° C. of this stock solution for spinning was more than 1000 dPa · sec, and the fluidity that did not hinder the solution feeding was not obtained, and spinning was not possible.

Example 3 An acrylic copolymer composed of 50% acrylonitrile, 48% vinyl chloride, and 2% sodium styrenesulfonate was prepared in advance in an amount 1.2 times that of sodium styrenesulfonate, which is the copolymer composition. A spinning stock solution having a copolymer concentration of 21% was obtained by dissolving in p-toluenesulfonic acid in a molar amount and mixing in acetone. The viscosity of this spinning dope at 40 ° C. was 150 dPa · sec. This spinning dope was spun through a spinning nozzle (pore size 0.20 mm, number of pores 200) into a coagulation bath containing 10% acetone water having a concentration of 10%. Then, it was introduced into a bath composed of 45% acetone water at 25 ° C., stretched 1.5 times, and passed through a bath composed of 15% acetone water. After that, it was passed through a washing bath composed of warm water of 40 ° C. and further stretched 1.5 times in a hot water bath of 80 ° C. Then, an oil agent in the step was attached and dried at 120 ° C. Subsequently, after stretching 2.5 times at the same temperature, 145 ° C
Was subjected to 10% relaxation treatment to obtain fibers. In the process from spinning stock solution preparation to spinning to finish the final fiber, various problems such as liquid sending ability of spinning stock solution, spouting of spinning nozzle, tow breakage in each bath including coagulation bath, winding around rollers, etc. There was no occurrence and the process was stable.

Comparative Example 2 The acrylic copolymer used in Example 2 was dissolved in acetone containing no p-toluenesulfonic acid to adjust the polymer concentration to 16% to prepare a spinning dope. Obtained. The viscosity of this spinning dope at 40 ° C is 2
It showed 30 dPa · sec. This spinning solution was passed through a spinning nozzle (pore diameter 0.20 mm, number of holes 200) at 10 ° C.
Although it was spun into a coagulation bath consisting of 10% acetone water in concentration, the spinning stock solution had poor releasability from the nozzle surface when the nozzle was erected, and the spinning tow solution was noticeably thick and brittle even when led to a take-up roll. Stable spinnability could not be obtained.

[0024]

INDUSTRIAL APPLICABILITY The spinning solution of the present invention is a solution of a sulfonic acid group-containing vinyl monomer in an acetone solution of an acrylic copolymer obtained by polymerizing acrylonitrile, vinyl chloride and a vinyl monomer containing a sulfonic acid group as main components. Despite the thickening phenomenon which becomes remarkable as the copolymerization ratio of the monomer increases, it is a low-viscosity spinning dope, so that it can be handled with a high spinning dope concentration. Especially in wet spinning, when the concentration of the spinning dope is low, the voids between the precipitated particles of the precipitated copolymer in the coagulation process become large, resulting in problems such as stable productivity in the fiber manufacturing process, fiber compactness, and fiber physical properties. However, it can be eliminated. Further, in wet spinning, a coagulation acceleration phenomenon is observed by containing a sulfonic acid compound in the spinning dope, and further stable productivity in the fiber manufacturing process can be expected.

Claims (4)

[Claims] 1. An acrylic copolymer obtained by polymerizing acrylonitrile, vinyl chloride and a vinyl monomer having a sulfonic acid group as a main component, and a sulfonic acid compound which does not copolymerize with these monomers are dissolved in acetone. Undiluted spinning solution. 2. The spinning dope according to claim 1, wherein the composition ratio of the sulfonic acid group-containing vinyl monomer in the acrylic copolymer is 1 to 3% by weight. 3. The spinning dope according to claim 1, wherein the sulfonic acid compound is toluenesulfonic acid. 4. A wet spinning method for an acrylic copolymer, which comprises wet spinning the spinning dope of claim 1.