JPS61108711A - Production of polyvinyl alcohol fiber of high strength and high elastic modulus - Google Patents

Abstract

PURPOSE:A solution of a PVA polymer of a specific polymerization degree is extruded through a spinneret with a plurality of nozzles under specific conditions, converted into gel without change in the concentration of the fibrous polymer solution, then desolvation and drawing are effected to produce the titled fibers of high uniformity and high strength and elasticity in high productivity. CONSTITUTION:A solution of polyvinyl alcohol of more than 1,500 polymerization degree is extruded through a spinneret having a plurality of nozzles under such conditions as the equation: 0.05<=V1/V0<=1.0 (V0 is the linear speed of the yarn extruded out of the spinneret; V1 is the yarn taking-up speed) and the resultant fibrous polymer solution is converted into gel without change in the concentration of the polymer solution. The resultant gel fibers are subjected to desolvation and drawing or drawing and desolvation at a total draw ratio of at least 13 into fibers of less than 10 denier each filament to give the objective fibers.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides high strength, high modulus polyvinyl alcohol (
(hereinafter abbreviated as PVA) type fibers, especially PVA, which has excellent fiber properties.
The present invention relates to a method for industrially and efficiently producing VA fibers.

(Prior art) Conventionally, a semi-diluted solution of an ultra-high molecular weight polyolefin polymer was discharged from a spinneret hole, the discharged yarn was cooled to form a -H gel, and the resulting gelled yarn was then treated with an IB2 solvent. However, it is known that fibers with extremely high strength and elastic modulus can be obtained by ultra-stretching [for example, Japanese Patent Application Laid-Open No. 56-154
08, Shu 58-5228 publications, Journal
of M materialsScience v
ol, 15.0505-514 (1980)],
Fibers made of PVA are also known (Japanese Unexamined Patent Publication No. 130314/1983).

High-strength, high-modulus fibers made from PVA-based polymers are expected to be highly useful in industrial and industrial fields due to their high melting point and weather resistance. A special polymerization method as disclosed in the official gazette (strict rectification of vinyl acetate monomer and -40℃
It is difficult to carry out industrially the ultraviolet polymerization (UV polymerization for a long time under PVA has low solubility in solvents, and when the high polymerization degree polymer is dissolved in a solvent, the polymer solution, that is, the spinning stock solution, lacks uniformity, and the polymer concentration is low due to the relationship between the solution viscosity of the spinning stock solution and the spinnability. This results in an unavoidable drop in productivity.

(Problems to be Solved by the Invention) The purpose of the present invention is not to use ultra-high polymerization degree PVA as used in the invention of JP-A-59-130314, but to use commercially available Using PVA having a degree of polymerization that can be produced manually,
The object of the present invention is to provide a method for producing PVA-based fibers having properties comparable to those disclosed in Japanese Patent No. 130314. Another object is to provide an industrial method for producing such ultra-high strength, high modulus PVA fibers.

(Means for Solving the Problems) The object of the present invention is to discharge a PVA polymer solution having a degree of polymerization of 1500 or more through a multi-hole nozzle under conditions that satisfy the following formula, After gelling the polymer solution without substantially changing the concentration thereof, the resulting gelled thread is stretched after removing the solvent or is subjected to a post-stretching solvent,
This can be achieved by a method for producing a high-strength, high-modulus PVA-based fiber, which is characterized in that the total draw ratio is at least 13 times and the single filament fineness is 10 deniers or less.

0.05≦V 1/V, ≦1.0 [In the above formula, ■o is the linear velocity of the discharged yarn when it is discharged from the spinneret, and V1 is the spinning take-off speed. ] The PVA used in the present invention is usually a commercially available or industrially producible polymer, but in order to obtain ultra-high strength, high elastic modulus dPvA fiber composite fiber, its degree of polymerization must be number average polymerization. Polymerization degree (P) is required to be 1500 or more, preferably 3000 or more, and P with a polymerization degree lower than 1500.
For VA polymers, the physical properties of the resulting fibers are determined according to the
It is difficult to make fibers with physical properties comparable to those of the PVA-based fibers described in Japanese Patent No. 9-'130314. In addition, it is preferable that the upper limit of the degree of polymerization is as high as possible,
A rough guideline can be approximately 6,000, which is within the range that is commercially available or industrially manufacturable. 600
PVA-based polymers with a degree of polymerization exceeding 0 are
When used as a raw material for producing VA polymers, special methods such as photopolymerization at low temperatures and for long periods of time, which are industrially impractical, must be used, and the degree of polymerization of the resulting polymer is low. If it is too high, it becomes difficult to avoid a decrease in productivity as a spinning dope as described above, which is not preferable.

The PVA-based polymer of the present invention is not limited to a single PvA polymer, but may also be one in which a small amount of other copolymerizable monomers, such as olefinic monomers such as ethylene, pyrene, and butylene, are copolymerized in the main chain. Partially saponified PVA that has not been completely saponified during the PVA manufacturing process, modified PVA that has been chemically treated, and other types of polymers that are miscible with these PV and A-based polymers.
% or less, it is possible to list the amount of water.

As the solvent for the above-mentioned PVA-based polymer, a solvent is used that heats and dissolves the polymer at a high temperature, and when the resulting solution is cooled, it becomes a gel. be non-volatile under the spinning conditions of the spinning dope so that when the yarn is cooled, the polymer concentration of the gelled yarn formed is substantially the same as the polymer concentration of the spinning dope before being discharged; is necessary. Furthermore, since the PVA-based polymer itself thermally decomposes at temperatures above its melting point (approximately 250° C.), the solvent is selected to be one that dissolves at a temperature below the melting point of the PVA-based polymer.

Examples of such solvents include ethylene glycol, glycerin, diethylene glycol, trimethylolpropane, benzenesulfonamide, and caprolactam.

The polymer concentration of the spinning dope obtained by dissolving in such a solvent is preferably 3 to 25% by weight.

The spinning stock solution is heated and discharged from the spinneret hole, and once introduced into a cooling bath via air or an inert gas. The distance between the spinneret surface and the liquid level of the cooling bath is between 3 and 100
A range of mg+ is preferable.

The cooling medium for the cooling bath liquid is preferably one that has the effect of simply cooling the yarn discharged from the spinneret without changing the polymer composition of the yarn. In other words, when mutual diffusion of solvent occurs between the discharged yarn and the coagulating liquid in the coagulating bath, such as in the coagulating bath used in wet spinning, a skin-core structure is formed in the cross section of the resulting fiber. ,
It becomes difficult to draw the fiber at a high ratio in the subsequent drawing step, and as a result, it becomes difficult to draw the fiber at a high ratio, which is the purpose of the present invention.
VA fibers cannot be obtained.

Therefore, since the solvent used in the present invention is hydrophilic, the cooling medium may be a hydrophobic liquid that is not miscible with the solvent for the polymer, such as decalin, trichloroethylene, or carbon tetrachloride. , paraffin oil, etc. are preferred.

The discharged yarn introduced into the cooling bath of such a cooling medium only needs to be cooled and gelled, so the polymer solvent itself, which does not dissolve the fibrous gelled yarn at the cooling temperature, is used as the cooling medium. You may.

The temperature of the cooling bath is determined by the gelling temperature of the spinning dope, and the humidity is such that the gelled yarn formed by cooling can be cooled to a sufficient degree to run stably in the subsequent process, and In order to improve the efficiency of cooling itself, it is preferable to maintain the temperature at about 50° C. or more lower than the gelling temperature.

For example, the degree of polymerization using glycerin as a polymer solvent is 30.
The gelation temperature of a 15% by weight solution of PVA-based polymer 00) is around 103°C, but in order to discharge this spinning stock solution from the spinneret hole and cool it, the temperature of the cooling bath must be set to 50°C.
It is best to do the following. In particular, in the production of multifilament yarn, the depth and length of the cooling bath liquid must be adjusted so that each gelled yarn (single yarn) discharged from the spinneret hole is cooled before being bundled together. should be set appropriately.

The polymer concentration of the gelled yarn thus obtained is substantially the same as the polymer concentration in the spinning dope, which means that the high strength, high modulus PVA fiber, which is the object of the present invention,
In particular, this is an important requirement in producing the high-property fiber made of PVA-based polymer having a degree of polymerization of 1,500 or more.

In the present invention, the discharge linear velocity (Vo) of the spinning stock solution and the take-up speed (■1) of the gelled yarn are set in conjunction with each other, and the range thereof is preferably 0.05≦V1/V0≦1.0. is preferably set to 0.05≦V 1/Vo≦0.5.

That is, in the present invention, the discharged yarn discharged from the spinneret hole into air or an inert gas such as nitrogen, helium, or argon is cooled by the cooling liquid, and in the process of gelling in the cooling bath, When tension is applied, the orientation of the polymer chains constituting the resulting gelled yarn in the fiber axis direction progresses, and the gelled structure becomes difficult to stabilize. becomes difficult. That is, the above formula means that the spinning take-off speed is lower than the discharge speed, but contrary to such conditions, the spinning conditions are adopted such that the spinning take-off speed is higher than the discharge speed. For example, JP-A-59-13031
No. 4 Publication Example), when using a PVA-based polymer with a degree of polymerization of 1500 or more as in the present invention, it becomes impossible to produce PVA-based fibers with high physical properties as the object of the present invention. be.

Of course, it is advantageous to lower the spinning take-off speed in order to reduce the resistance of the cooling bath liquid against the running yarn in the cooling bath. This can be achieved by flowing the cooling bath liquid along the traveling direction of the running yarn.

The gelled yarn thus obtained is stretched after being subjected to solvent removal treatment, or is subjected to solvent removal treatment in a drawing machine, but the degree of orientation of the polymer chains in the fiber axis direction of the gelled yarn is small, and a homogeneous fiber structure cannot be obtained. It has extremely excellent stretchability. However, the stretching ratio is at least 13 times or more, preferably 16 times or more, with respect to the original length of the discharged yarn, and the single yarn m
It is necessary to make the polygon fiber 10 denier (d) or less, preferably 5 d or less, and by performing such stretching, it is possible to obtain a PVA-based fiber with high strength and high elastic modulus, which is easy to handle in the spinning process. This makes it possible to obtain fiber yarns that have good high-order processability and can be processed into a variety of products.

In addition, the fineness of the single filament depends on the fineness of the undrawn yarn immediately after spinning, but if the fineness of the undrawn yarn is thick, the fineness of the single filament during cooling gelling or the subsequent desolvation treatment process will increase the fineness of the undrawn yarn. A large structural difference is likely to be formed between the inner and outer structures, making it difficult to uniformly draw the entire single yarn at a high draw ratio with no difference in inner and outer structures.From this point of view as well, the single yarn fineness is preferably 106 or less. .

Note that the solvent removal treatment is performed by extraction treatment using a liquid that is miscible with the solvent of the polymer and is a non-solvent for the polymer. The yarn, which has been thoroughly desolvated and contains the extractant, is roughly dried to remove the extractant, and then subjected to a drawing process.

When using a drawing machine to remove solvent, it is preferable to carry out hot drawing at a temperature below the melting point of the gelled yarn, and when post-stretching is performed after removing solvent, draw at a temperature lower than the melting point of the PVA polymer. For example, it is preferable to carry out hot stretching at a temperature in the range of 160 to 250°C. Further, the above-mentioned stretching can be either one-stage stretching or multiple-stage stretching.

Equipment used for hot stretching includes heating tubes, hot plates,
Various devices can be used that use heating rolls, heated bottles, heated liquids, fluidized beds, etc. as heating means.

(Effects of the Invention) According to the present invention, commercially available or industrially producible P having a degree of polymerization of 1,500 or more and 6,000 or less
Using VA-based polymer, the tensile strength is at least about 16a
/d, and a tensile modulus of about 300a/d or more, which makes it possible to industrially produce high-strength, high-modulus PVA fibers.

Moreover, the PVA-based fiber obtained by the present invention is a multifilament with a single filament fineness of 10 d or less, unlike the monofilament proposed in JP-A-59-130314. It is extremely useful because it is not only easy to handle, but also easy to perform high-order processing and can provide a wide variety of products.

Hereinafter, the effects of the present invention will be explained in more detail based on Examples and Comparative Examples.

In addition, in the following examples and comparative examples, the formula ■1/V,
This is called a spinning draft. In addition, the physical properties of the fibers are values measured under the following conditions.

Measurement sample: Single yarn trial length: ・100ffll
Tensile speed: 10 (1 m/min Atmosphere = 20°C, 65% relative humidity Example 1 PVA polymer with a degree of polymerization of 2100 (degree of saponification 99.5%)
was dissolved at 170° C. using glycerin as a solvent to prepare a spinning solution having a polymer concentration of 17.5% by weight. The stock solution was extruded into the air at 170°C through a nozzle with a hole diameter of 0.08 + 111° and a number of holes of 10.
It was cooled by passing through a liquid bath consisting of decalin at °C. The total discharge rate of the stock solution from the nozzle was 0.97 CO/min, and the cooled rubbery gel yarn was taken off at 5111/min. The spinning draft at this time was 0.26.

The rubbery gel thread was then stretched 4.0 times in a heating tube having a length of 8 Qcm and whose internal air temperature was set to 100° C., and wound onto a plastic bobbin.

The wound yarn was repeatedly soaked in warm water at 40° C. along with the bobbin to extract glycerin, which is a solvent contained in the fibers. The film was then dried to remove water, and hot-stretched using a hot plate with a surface temperature of 230°C.

Table 1 shows the physical properties of the obtained fibers.

In Table 1, the strength exceeds 16a/d and 30o
It can be seen that I fibers having an elastic modulus exceeding /d can be obtained.

Example 2 PVA polymer with a polymerization degree of 3900 (saponification degree 99.6%)
was dissolved in glycerin as a solvent at 170°C to prepare a spinning dope having a polymer concentration of 11.0% by weight. The stock solution maintained at 170° C. was extruded into air through a nozzle with a hole diameter of 0.061111 and 20 holes, and passed through the nozzle into a liquid bath of decalin at 15° C. under 'IQIII' for cooling. The total discharge rate of the stock solution from the nozzle was 0.97 cc/min, and the cooled rubbery gel thread was drawn off at a rate of 2 m/min. The spinning draft at this time was 0.12.

The rubbery gel thread was then stretched 4.0 times in a heating tube having a length of 800 m+ and whose internal air temperature was set to 100° C., and then wound onto a plastic bobbin.

The wound yarn was repeatedly soaked in warm water at 40° C. along with the bobbin to extract glycerin, which is a solvent contained in the fibers. The film was then dried to remove water, and further stretched 5.5 times using a hot plate with a surface temperature of 230°C.

The total stretching ratio was 22 times, and the fineness was 1.54 d.

Strength 20.1/d1 Elongation 4.9%, Modulus of elasticity 430Q/d
PVA fibers were obtained. This physical property value significantly exceeds that of previously known PVA fibers,
Even if you do not use a polymer with a significantly high viscosity average molecular weight of 2.7 million as described in JP-A-59-130314, it is possible to use industrially produced and available PVA as a raw material. Fibers with physical properties are obtained.

Comparative Example 1 Using the same spinning dope as in Example 1, the temperature was 170°C and the pore size was 0.
Extruded into the air from a 30m11 nozzle with 12 holes,
It was cooled by passing it through a liquid bath consisting of decalin at 15° C. 8 cm below the nozzle. The total amount of liquid discharged from the nozzle is 3.8C.
C/min, and the cooled rubbery gel thread was drawn off at 5 m/min. The spinning draft at this time was 1.12. The rubbery gel thread was then stretched 4.0 times in a heating tube having a length of 80C11 and whose internal air temperature was set to 80°C, and then wound onto a plastic bobbin. The wound yarn was immersed together with the bobbin in warm water at 40°C, the solvent was removed, and the yarn was dried, and then stretched on a hot plate with a surface temperature of 230°C. As a result, the total stretching ratio was 12 times, the fineness was 1°, and a little over 15d1 Fm1.
1.80/d, elongation [4.0%, elastic modulus 315q/d
of fibers were obtained.

This indicates that when the spinning draft is high, the draw ratio cannot be increased sufficiently and fibers with high mechanical strength cannot be formed.

Example 3 In Example 1, when ethylene glycol was used as the polymer solvent and yarn was spun under the same conditions as above, the total draw ratio remained at the maximum of 16 times, the fineness was 2.25 d, and the strength was 18.
．． A fiber having physical properties of 39/d 1 elasticity modulus of 384Q/d was obtained.

Comparative Example 2 The same spinning dope as in Example 1 was used with a 170'C1 pore diameter of 0°301
11I111 Pushed into the air from a nozzle with 12 holes,
It was cooled by passing it through a liquid bath consisting of decalin at 15° C. 5 mm below the nozzle. The total discharge m of the stock solution from the nozzle is 3.8
CC/min, and the cooled rubbery gel thread was
I picked it up in minutes. The spinning draft at this time was 0.67. The rubbery gel thread was then cut to a length of 80c+a.
4. in a heating tube with an internal air temperature set at 80°C.
It was stretched 0 times and wound up on a plastic bobbin. The wound yarn was immersed together with the bobbin in dry water at 40°C, the solvent was removed, and the yarn was dried, and then stretched on a hot plate with a surface temperature of 230°C. As a result, the total stretching ratio was 14 times, but the fiber physical properties were
Fineness 16.2d, strength 12.2o/d, elongation 4.1%,
The elastic modulus was 297 g/d.

Comparative Example 3 PVA polymer with a degree of polymerization of 1300 (degree of saponification 99.5%
) was dissolved at 160° C. using glycerin as a solvent to prepare a spinning dope having a polymer concentration of 20% by weight. 16% of the stock solution
It was extruded into air at 0°C through a nozzle with a hole diameter of o, osn+s, and number of holes of 10, and passed through a liquid bath of decalin at 15°C under 8 ml of 1 liter of the nozzle to cool it. The total discharge rate of the stock solution from the nozzle was 0.97 cc/min, and the cooled rubbery gel thread was drawn off at a rate of 5 m/min. The spinning draft at this time was 0126.

The gel thread is then stretched 4 times in a heated tube,
Desolvent, dry, and heat on a hot plate at 230'C for another 4.8
A drawn fiber yarn with a total draw ratio of 19.2 is
is.

The obtained fiber had a low degree of polymerization of the polymer used, and its physical properties remained at the level of conventional PVAwA miscellaneous materials, with a fineness of 2.3 d, strength of 13.5 a/d, elongation of 6.1%, and elastic modulus of 354 g/d.
The fibers were

Claims (1)

[Claims] (1) A polyvinyl alcohol polymer solution with a degree of polymerization of 1500 or more is discharged through a multi-hole nozzle under conditions that satisfy the following formula, and the fibrous polymer solution is gelled without substantially changing its concentration. After stretching, the obtained gelled yarn is stretched after desolvation or desolvated after stretching to obtain a drawn yarn having a total stretching ratio of at least 13 times and a single filament fineness of 10 deniers or less. A method for manufacturing polyvinyl alcohol-based fibers featuring high strength and high modulus of elasticity. 0.05≦V_1/V_0≦1.0 [In the above formula, V_0 is the linear velocity of the discharged yarn when it is discharged from the spinneret, and V_1 is the spinning take-off speed. ](2)
In claim 1, the degree of polymerization of the polyvinyl alcohol polymer is 3000 or more, and V_1/V_
0 satisfies the following formula, 0.05≦V_1/V_0≦0.5, the total draw ratio is 16 times or more, and the single fiber fineness is 5 denier or less. A method for producing high strength, high elastic modulus polyvinyl alcohol fiber. .