JPS5947692B2 - Method for producing molding solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention refers to spinning and molding of an acrylonitrile polymer.

The present invention relates to a method for producing a solution (the same applies hereafter), and more specifically to a method for producing a solution for spinning and molding from a wet acrylonitrile polymer produced by aqueous precipitation polymerization.
. Acrylonitrile polymers are often produced in an aqueous medium. The reason for this is that water, which corresponds to the solvent, is inexpensive. The reaction rate in the aqueous medium in which the produced polymer precipitates is that of dimethylformamide, dimethyl sulfoxide, and dimethylacetamide. The reaction is much faster than that in organic solvents such as carbonate, ethylene carbonate, etc.
The reaction time is short, the productivity is high, there is a wide range of catalysts to choose from, allowing the use of azobis-based organic catalysts that are soluble in monomers, as well as redox initiators that are soluble in water; This is because it has many industrial advantages, such as low viscosity, simple equipment, easy removal of reaction heat, and easy separation of the produced polymer. On the other hand, if the spinning solution produced from these wet polymers contains about 1.5% by weight or more of water, the solution using a solvent such as dimethylformamide will cause gelation and the spinning will become difficult. It has been reported that it can be difficult. Therefore, conventionally, when producing a spinning solution containing an acrylonitrile polymer, a dry polymer is used, that is, the water content in the spinnable polymer solution is reduced to 1.5
It was thought that it was necessary to reduce the amount by weight% or less. When this polymer is spun using a normal dry or wet spinning method, a solvent for the polymer is added so that the polymer concentration is approximately 30% by weight or less, and the polymer is dissolved by heating to a concentration of 60°C or higher. Usually, the spinning solution is prepared by In the conventional process of producing a spinning solution from such acrylonitrile-based polymer, after drying the wet polymer in a dryer,
A solvent for the polymer is added to this and dissolved by heating.

It has long been thought that such processes should be improved due to the large amount of heat required and the negative effects that exposing the polymer to high temperatures has on spinnability and yarn quality. For this reason, methods to replace heat drying have been researched in various fields, but in all cases, the water content in the spinning solution is reduced to 1.5% by weight.
Either it cannot be achieved, or even if it could be achieved, it has not yet been industrialized due to extremely low productivity. One of the methods is to replace the water in the wet polymer with a solvent or non-solvent and filter it. The method of replacing the solvent with a solvent has been shown to reduce the water concentration in the solution spinning composition by 3% even on a laboratory scale due to clogging of the furnace cloth and an extreme decrease in the filtration rate, which are thought to be caused by dissolution of the polymer. There is no report yet that it has been possible to achieve a reduction of % or less. However, the adoption of the above method on an industrial scale, where large quantities must be processed,
Even if it were possible for the spinning solution to contain about 3% by weight of water, it would not be practical. In addition, the water replacement method using organic nonsolvents (acetone, methanol, etc.) results in new nonsolvents being included in the spinning solution in addition to the polymer, solvent, and water, and it is only necessary to recover this nonsolvent. However, it has not been commercialized due to deterioration in spinnability, deterioration in yarn quality, etc. The second dehydration method reported in the past is a method using vacuum distillation.

In this method, after the washed polymer is separated and taken out by filtration, a solvent for the polymer is added, and water is distilled off under reduced pressure due to gas-liquid equilibrium to obtain a spinning solution. Although this method has features such as extremely high thermal efficiency compared to the aerated drying method and no scattered gas, there are defects in the solution properties such as concentration unevenness in the spinning solution, and in addition, there is an enormous amount of heat transfer. It is far from being realized because of difficulties in terms of equipment such as the necessity of area and evaporation area. Other methods for removing water from wet polymers can be roughly divided into the conventionally used aerated drying method and a method that combines the two methods mentioned above. It has not moved beyond the laboratory stage.

In view of the current situation, the inventors of the present invention have worked hard day and night, and as a result of intensive research, they have arrived at the surprising invention described below.

The invention is a method for reducing the liquid content in a wet polymer to 10% by weight or less under high pressure. When producing a spinning solution from an acrylonitrile polymer, a solid-liquid separation step is required to extract the polymer as a wet polymer from the slurry, but conventional methods involve separation by filtration or centrifugal dehydration. It has mainly been done.

With these methods, it was not possible to achieve a polymer concentration in the wet polymer of 50% by weight or more. However, as the present inventors continued their research, they surprisingly discovered that by squeezing a wet polymer under high pressure, the liquid content in the polymer could be reduced to 10% by weight or less. The present invention will be explained in more detail.

The most important point of the present invention is to add the dissolved acrylonitrile-based polymer to a composition consisting of the polymer, water, solvent, and other trace impurities, and then press and remove liquid to obtain a polymer concentration of 60% by weight. or more, preferably 80% heavy flow% or more,
The solvent is further added to the obtained polymer mass to dissolve the polymer, thereby producing a molding solution having a polymer concentration of 5 to 30% by weight. Acrylonitrile polymers that can be used in the present invention include 100% acrylonitrile polymers,
Copolymers of 50% by weight or more of acrylonitrile and other copolymerizable monomers are included. Furthermore, a wide variety of inorganic and organic solvents are known as solvents for polymers, and all of them and mixtures thereof are applicable to the present invention. Typical solvents include organic solvents such as N,
N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, nitric acid as an inorganic system,
Nitrates, mouth salt aqueous solutions, etc. are listed. In the method for producing a spinning solution according to the present invention, the acrylonitrile polymer is produced in an aqueous medium, and after appropriate water washing if necessary, the polymer is taken out as a slurry or a wet mass. The solution of the aforementioned polymer is then added to a solution containing approximately no more than about 9 times the water content in the slurry or wet mass that has been removed.
Preferably, about 4 times the amount is added, and while gradually removing the liquid, the liquid is finally squeezed out at a surface pressure of 100 kg/d or more to obtain a wet polymer. This polymer is taken out as a wet composition containing 60% by weight or more of solid content and 40% by weight or less of liquid content.
A major feature of the present invention is that after adding a polymer solvent, a wet polymer containing a solid content of 60% by weight or more, preferably 80% by weight or more is obtained by mechanical compression. There are two types of presses used for the squeezing operation: batch type and continuous type.Specific examples of batch type include piston-cylinder type presses, Kaba single-hydraulic type presses, etc. Piston-cylinder type presses are press machines that press a piston into a cylinder, and range from small to large sizes, and the squeezing pressure can be freely changed within a range of up to 2000 kg/i. The Kaba-hydraulic deep overpressure machine filters the slurry at a pressure of 50 kg/d, removes much of the liquid, and then deliquifies it by pressing at a pressure of 100 k9/d or more. The difference is that the raw materials can be added in the form of a slurry, which is industrially advantageous. Other batch-type presses include plate presses, box-type presses, pot presses, and cage presses, but all of them are normally used with a squeezing pressure of about 100 kg/d or less, and when used in the process of the present invention, needs improvement. Continuous presses include the Anderson type expeller and the Frente type screw press, both of which use a screw to perform compression, and the compression pressure is said to reach 700 to 1000 kg/d. . Such a continuous press has recently been improved so that the pressed material can be supplied in the form of a slurry, and its use in the present invention brings about industrially advantageous results. Furthermore, some of the above-mentioned presses are equipped with a stripping mechanism, which greatly contributes to the present invention in terms of removing liquid, and its use is recommended. When a polymer solvent is added to a wet compressed mass obtained using such a press with a liquid content of up to 40% by weight, the polymer is dissolved and a good spinning solution is obtained.

As mentioned repeatedly, the feature of the present invention is to add a solvent for the polymer to a water-containing polymer in an amount that does not dissolve the polymer, and then mechanically squeeze out the liquid to obtain a composition with a polymer concentration of 60% by weight or more. After that, further solvent is added to obtain a polymer concentration of 5 to 30% by weight.
In the production of molding solutions, the industrial application of the present invention yields a number of advantages, including:

Firstly, the amount of heat required is greatly reduced due to the fact that water is mechanically separated and removed without causing any phase change. When comparing dehydration using the aerated drying method with the present invention, the amount of work required in the present invention in terms of heat is 1/1000 or less than that of the method using the aerated drying method. Second, since dehydration is possible without applying heat, the polymer can be avoided from being thermally denatured, resulting in improved yarn quality and spinnability. Thirdly, it is extremely easy to prevent components from escaping due to the fact that there is no handling of the gas phase, and fourthly, the process is simplified and the equipment can be small. Next, the present invention will be explained in more detail with reference to Examples.

In the examples, all percentages and parts other than those for whiteness and elongation of the fibers are based on weight. Example 1 100 parts of a copolymer consisting of 93% acrylonitrile and 7% vinyl acetate,
A slurry consisting of 600 parts of water was subjected to solid-liquid separation using a centrifuge to obtain a wet polymer consisting of 100 parts of copolymer and 100 parts of water.

Subsequently, 400 parts of N,N dimeterformamide (DMF) was added to this wet polymer, the mixture was slurried at 20°C, and solid-liquid separation was performed using a centrifuge again to obtain 100 parts of polymer, 20 parts of water, A wet polymer consisting of 80 parts of DMF was obtained. Put this polymer into a 125nφ cylinder and use a piston to
By pressing at 0.00 kg/d, a composition consisting of 92 parts of polymer, 3.5 parts of water, and 14 parts of DMF was obtained (8 parts of the polymer were leaked). After pulverizing this with a hammer mill, 500 parts of DMF was added and dissolved at 80°C to produce a spinning solution. The composition of this solution was 15.1% copolymer, 0.6% water, and 4.3% DMF8. The viscosity of the obtained spinning solution was 32 poise at 50°C;
After standing for 7 days, the viscosity was 35 poise, indicating extremely good viscosity stability. When the obtained solution was spun using a typical wet spinning method for acrylonitrile copolymer, the whiteness was 9.5.1% (the magnesium oxide plate was
00 (the same applies below), a good fiber with an elongation of 12.9% could be obtained. Example 2 A copolymer consisting of 93% acrylonitrile and 7% pinyl acetate obtained by precipitation polymerization was washed with water to obtain 100 parts of the copolymer.
A wet polymer consisting of 200 parts of water was obtained.

This polymer was added with N,N-dimethylacetamide (DMA).
c) Add 600 parts and separate the solid and liquid by passing through the door to obtain copolymer 1.
A wet polymer was obtained consisting of 0.00 parts of water, 50 parts of water, and 150 parts of DMA c. This was put into a 125aφ cylinder and compressed with a piston at a surface pressure of 900kg/d to obtain 91 parts of polymer.
A wet polymer consisting of 3.6 parts of water and 10.8 parts of DMAc was obtained. After crushing this polymer with a hammer mill, DMAc4
When 00 parts of the solution was added and dissolved at 70°C, a uniform spinning solution was obtained. This solution contains 18.0% copolymer and 0.7% water.
It contained %. This was wet-spun using a conventional method, and the resulting yarn was drawn, washed, oiled, and dried, resulting in a whiteness of 9.
6.0%, elongation 13.0%, strength 2.4 8'/
The denier was comparable to that of conventional fibers. Example 3 Acrylonitrile 9 5 Cf6, methyl acrylate 4
．． A slurry consisting of 100 parts of a copolymer of 5% sodium vinylbenzenesulfonate and 0.5% of sodium vinylbenzenesulfonate and 500 parts of water was separated into solid and liquid by centrifugation to obtain 100 parts of the polymer and 130 parts of water.
A wet polymer consisting of 50% was obtained.

To this was added 50 parts of DMA c6 to form a slurry, which was poured into a cylinder provided with a strainer cloth, and then gradually compressed with a piston to a pressure of 200 k9/i. The composition of the obtained wet polymer was 100 parts of polymer, 5.1 parts of water, DMAc2
It was 5.5 parts. After crushing this wet polymer, DMAc3
When the OO part was added and dissolved at 70°C, a uniform spinning solution was obtained. The spinning solution was 23.2% polymer and 1.2% water.
%, and DMAc 75.6%. When this solution was spun in the same manner as in Example 2, a fiber with good whiteness of 95.0, strength of 2.50 f/denier, and elongation of 13.2 (L) was obtained.Example 4 63 parts of acrylonitrile, An acrylonitrile copolymer slurry prepared from a reaction mixture consisting of 17 parts of methyl acrylate and 708 parts of water was injected into a Carba type hydraulic overpress at a pressure of 30 kg/d to form a solid mass.

This finished mass contains 100 parts of copolymer and 150 parts of water (solid component: 4 parts).
0%, moisture 60%). Next, dimethyl sulfoxide (DMSO) was added to this finished lump to reduce the water content in the finished lump.
After adding twice as much and making it into a slurry, the pressure is 30
After injecting at k9/d to form a deep mass, 150k9
The squeezing operation was performed at a pressure of /d. At this time, the pressed mass consisted of 100 parts of polymer and 54 parts of dissolved matter (65% solid content). Subsequently, 200 parts of DMSO were added and dissolved at 60°C to obtain a spinning solution. The composition of this spinning solution is copolymer 1
00 parts, water 9 parts, DMSO 245 parts (copolymer 28.2 parts
%, water 2.5 (F6, DMSO 69.396). When this spinning solution was spun using a typical wet spinning method for acrylic fibers, the whiteness was 95.8% and the elongation was 13.1%.
A good fiber with a strength of 2.52 f/denier was obtained. Example 5 Acrylonitrile 93.63%, methyl acrylate 6.0%, sodium styrene sulfonate 0.37%
After washing the copolymer consisting of 100 parts of copolymer and 40 parts of water,
I took it out in the form of 0 copies.

To this slurry, DMAc2OOOO parts were added and stirred, followed by centrifugation to obtain a composition consisting of 100 parts of copolymer and 100 parts of liquid. When this composition was put into a cylinder and squeezed with a piston at a pressure of 400 kg/i,
A pressed mass consisting of 95 parts of copolymer (5 parts leaked and 28 parts of liquid was obtained. After crushing this press, DMAc3OO
When the slurry was heated to 60° C. and dissolved, a uniform spinning solution was obtained. The spinning solution consisted of 23.6% copolymer, 1.1% water, and 75.3% DMAc and was heated to 135°C and then extruded through a spinneret into a typical dry spinning cell. When filament yarns were spun using spinning conditions typical for acrylic fibers, extracted in water at 98°C and stretched 4 times at the same time, and further dried at room temperature, the resulting fibers had a strength of 3.01 f/ The denier and elongation were 13.5%, which were equivalent to those produced by conventional manufacturing methods. Example 6 The same copolymer as in Example 5 was washed and then subjected to solid-liquid separation by filtration to obtain a composition consisting of 34% copolymer and 66% water.

This composition was passed through a barrel (30!n) with a slit for solid-liquid separation.
In addition to the screw press installed in the copolymer, DMF was injected into the barrel at a pressure of 50 kg/i after some of the water had been separated, and the liquid was subsequently separated from the copolymer. The copolymer mass taken out from the tip of the barrel is copolymer 100.
After pulverizing this, DMF was added and dissolved at 65°C to obtain a uniform spinning solution consisting of 20.2% copolymer, 1.8% water, and 78% DMF. It was done. After heating this spinning solution to 140°C, it was extruded from a spinning nozzle into a typical dry spinning cell, subjected to simultaneous 4-fold stretching and extraction in water at 98°C, and dried with a roll heater to obtain an acrylonitrile filament yarn. . The whiteness of the obtained fiber was 96.3% and the elongation was 14.0%. Example 7 The same copolymer as in Example 3 was washed with water and then subjected to solid-liquid separation by filtration to obtain a copolymer (1f. 34%, water 66% composition).

After adding 800 parts of DMAc to 300 parts of this composition to form a slurry, solid-liquid separation was performed by filtration to obtain copolymer 102.
A composition containing 200 parts of liquid was prepared. Composition 3
When processed using a screw press with a barrel of 01t111φ, an apparently dry lump of polymer was taken out from the outlet of the press, and after crushing this, the composition was investigated: 73.2% copolymer, 5.5% water. 3%, DMAc2l. 45%
It was hot. DMAc was added in an amount four times that of the copolymer to this composition and dissolved at 75°C, resulting in a copolymer of 22.6%, water 1.65%, and DMAc 75.75% (for uniform and viscous spinning consisting of F6). A solution was obtained. When this solution was spun using a wet spinning method typical for acrylic fibers, the whiteness was 96.1.
% and an elongation of 13.4%.

Example 8 Acrylonitrile 92Cf1), methyl acrylate,
A polymer slurry consisting of 100 parts of a copolymer of vinylbenzene sulfonic acid 1% and 700 parts of water was filtered under reduced pressure to obtain a wet lacrimal mass consisting of 100 parts of the copolymer and 2200 parts of water.

Add 100 parts of a 10% nitric acid aqueous solution to this moist tear mass and -1
After slurrying the slurry with 0% water, the slurry was deliquified by pressing at a pressure of 200 kg/d to obtain a composition consisting of 100 parts of the copolymer and 50 parts of liquid. After crushing this composition with a hammer mill, 75 (
fl) Add 308 parts of a nitric acid aqueous solution and dissolve at -5°C (at this time, the concentration of the nitric acid aqueous solution is 65 parts of nitric acid, and the polymer can be uniformly dissolved).

) to obtain a uniform spinning solution with a polymer concentration of 21.8 (fl). Next, this spinning solution was wet-spun in a 28-degree nitric acid aqueous solution at -5°C, washed in boiling water, and washed for 6 hours.
When dried at 0'C and further treated with steam at 120 oki, the strength was 2.6 f/denier and the oki degree was 15.8 (F6
A fiber bundle showing the following was obtained.

Example 9 A polymer slurry consisting of 100 parts of a copolymer consisting of acrylonitrile 93Cf6 and pinyl acetate 9(:L), 600 parts of water, and 5 parts of acrylonitrile was separated into solid and liquid using a centrifuge to obtain 100 parts of polymer and about 198 parts of water. A wet lacrimal mass consisting of about 2 parts of unreacted acrylonitrile was obtained.

Claims (1)

[Claims] 1. A solid-liquid mixture obtained by adding a solution to a water-containing acrylonitrile polymer obtained by an aqueous precipitation polymerization method is squeezed to obtain a solid content of 60% by weight or more.
A composition with a liquid content of 40% by weight or less is prepared, and then a solvent for the polymer is added to the composition to obtain a polymer concentration of 5 to 3%.
A method for producing a molding solution, characterized in that the solution is 0% by weight.