JPH0670283B2 - Method for producing high-strength, high-modulus polyvinyl alcohol fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a polyvinyl alcohol (hereinafter abbreviated as PVA) fiber having high strength and high elastic modulus, particularly an industrial or commercial production method thereof. Regarding

[Prior Art] Conventionally, a semi-dilute solution of an ultra-high molecular weight polyolefin-based polymer is spun, and the obtained discharge yarn is cooled to gel,
It is known that when the solvent is extracted from the gelled yarn and then the fibers are subjected to ultra-drawing, fibers having extremely high strength and elastic modulus can be obtained (JP-A-56-15408, JP-A-58-5228). Publications and Journal of Materials Science Vol.15,50
5 to 514, 1980 and 2584 to 2590, 1980).

As a method for producing ultra high strength and high modulus fibers by applying the above-mentioned gel spinning using ultra high polymerization degree PVA, JP-A-59-13
In the 0314 publication, first, by polymerizing a strictly rectified vinyl acetate monomer, which is a PVA raw material, at a low temperature of −40 ° C. or lower by irradiating with ultraviolet light for a long time of about 100 hours,
An ultra-high degree of polymerization PVA with a degree of polymerization exceeding 6000 was created, and using this ultra-high degree of polymerization PVA, the gel spinning method, that is, the yarn obtained by discharging the spinning dope from the spinneret was used to cool the gel. A method for producing high-strength and high-modulus fibers by the method of producing fibers from this gelled yarn is disclosed.

However, in such gelling spinning method,
When a multifilament yarn composed of a large number of monofilaments, which is generally produced, is produced separately from the monofilament, the monofilaments constituting the multifilament yarn are easily fused to each other. There is a problem that the fiber has poor flexibility, the strength of the whole fiber is low, the strength is lowered by high-order processing such as twisting, and the strength utilization rate is low.

Also, with a high degree of polymerization PVA with a degree of polymerization exceeding 6000, it is difficult to prepare a high-concentration polymer solution with good uniformity, and the spinning stock solution with a high polymer concentration has a remarkably high viscosity. As the spinning stock solution has to be used as a spinning stock solution, a solution having a low polymer concentration must be used.However, a spinning stock solution having a low polymer concentration has a low productivity in fiber production, and there is a problem that an industrial production method cannot be adopted. is there. Then, in the gelling spinning method, when water is used as a cooling bath for gelling the discharged yarn, the gelled yarn in a wet state is easily fused, and the solubility and handling in PVA-based polymer, It has the drawback that water, which is advantageous in terms of safety, cannot be used.

Further, the method for producing a special PVA as described in JP-A-59-130314 is not at least an industrial method for producing a polymer, and can be said to be one of the reasons for limiting its industrialization.

[Problems to be Solved by the Invention] As a method for producing a high-strength / high-modulus PVA-based fiber, the present inventors have described the ultrahigh strength described in JP-A-59-130314.
The present invention has been made through intensive studies on a method for industrially and cost-effectively producing a PVA-based fiber having physical properties comparable to those of a PVA-based fiber, and found the present invention.

That is, the purpose of the present invention is to show excellent physical properties in strength and elastic modulus, without fusion between single fibers, rich in openability and flexibility, PV excellent in high-order processability
It is an object of the present invention to provide a method for producing an A-based fiber with high productivity and technically advantage.

Hereinafter, the present invention will be described in more detail and specifically.

[Means for Solving Problems] An object of the present invention is a solvent which dissolves a PVA polymer having a degree of polymerization of 2000 or more and 6000 or less in a temperature range of 80 ° C. or more and below the melting point of the polymer. Which is dissolved in a solvent that is miscible with water, is discharged from the spinneret as a spinning stock solution, and the discharged yarn is against the solvent of the spinning stock solution kept below its gelling temperature. After introducing into a non-miscible cooling bath to form a gelled yarn, the obtained gelled yarn is hot-stretched at a temperature below its melting point, then desolvated with water, and then According to the method for producing high-strength, high-modulus polyvinyl alcohol-based fibers, which is characterized in that it is dried and secondarily drawn to obtain a drawn yarn having a total draw ratio of at least 15 times and no fusion between single fibers. To be achieved.

As the PVA-based polymer used in the present invention, conventionally known PVA
Examples of the VA and its derivatives include, but are not particularly limited to, not only fully saponified PVA but also olefinic monomers such as ethylene, propylene and butylene as a copolymerization component in the main chain. Small amount of copolymerized and partially saponified PVA or chemically post-treated PVA without complete saponification in PVA manufacturing process
Examples include polymer-based polymers and blends with other polymers having miscibility with a small amount of PVA of 10% by weight or less.

These PVA-based polymers have a degree of polymerization of 2000 (88,000 in terms of molecular weight) or more and 6000 (264,000 in terms of molecular weight) or less. When the polymerization degree is less than 2000, it is not possible to obtain a fiber satisfying the ultra-high strength physical properties of the present invention, on the other hand, when the polymerization degree exceeds 6000, the production cost of the PVA polymer itself is high, Not only is it difficult to obtain commercially, but it becomes difficult to produce a solution having a concentration and a viscosity that can be spun with good productivity as a spinning stock solution,
It becomes difficult to industrially manufacture PVA fibers by spinning or spinning.

The PVA polymer of the present invention having such a degree of polymerization is dissolved so that the polymer concentration is within the range of 5 to 25% by weight to prepare a spinning dope.

Here, when the polymer concentration is lower than 5%, the productivity becomes poor and the cost burden of solvent recovery increases, while
If it is higher than 25%, the viscosity of the spinning dope is too high, resulting in a large pressure loss in the polymer channel and a difficulty in stable flow.

As the solvent for the PVA-based polymer used in the preparation of the spinning solution, the PVA-based polymer is melted at a temperature not higher than its melting point and 80 ° C. or higher, and the resulting solution is gelated by cooling, specifically, Among the non-volatile solvents at room temperature such as ethylene glycol, glycerin, diethylene glycol, trimethylolpropane, benzenesulfoamide, and caprolactam, glycerin, which has miscibility with water, or ethylene glycol, or a mixture thereof. It is used. The spinning dope is prepared by dissolving the PVA polymer in the above solvent which is heated to a temperature range of 80 ° C. or higher and below the melting point (about 250 ° C.) of the polymer. When the polymer is dissolved in a solvent having a temperature higher than the melting point of the polymer, the polymer is decomposed, which is not preferable, and when the temperature is lower than 80 ° C., for example, it is difficult to gel in a range of normal temperature to 0 ° C. and it becomes difficult to obtain a stable gel yarn.

The spinning stock solution thus obtained is discharged from the spinneret hole, but the spinning stock solution may be directly discharged into the cooling bath, or once discharged into an inert gas such as air or nitrogen, helium or argon, It may then be introduced into the cooling bath. When discharging into air or an inert gas, it is preferable that the temperature of the air or the inert gas is 0 to 80 ° C., and the distance between the spinneret surface and the cooling bath is about 3 to 50 mm.

Here, as the cooling bath liquid, a hydrophobic liquid that is not compatible or miscible with the solvent of the PVA polymer, such as decalin, trichlorethylene, carbon tetrachloride, paraffin oil, or kerosene is used. By using a different cooling liquid, the yarn gelled in the cooling liquid is
The polymer concentration is kept substantially the same as the polymer concentration of the spinning dope, and it becomes possible to produce the high-strength, high-modulus PVA fiber of the present invention only by such gelled yarn.

That is, when the cooling liquid is compatible and miscible with the solvent of the polymer, mutual diffusion occurs between the polymer solvent in the discharge yarn and the cooling liquid in the cooling liquid, and, for example, the skin. Thus, a structure such as a core is formed, and it becomes difficult to obtain a dense and highly stretchable gel yarn.

Here, the temperature of the cooling liquid is determined by the gelation temperature of the spinning dope, but is preferably in the range of 0 to 60 ° C. That is, when the temperature is higher than 60 ° C, the cooling efficiency of the discharged yarn is insufficient, so that it becomes difficult to stably run the yarn in the subsequent processes such as desolvation and drawing, and the temperature is higher than 0 ° C. If it becomes lower, special cooling equipment is required, which is not preferable.

For example, in the case of a 15 wt% glycerin solution of PVA having a degree of polymerization of 3000, its gelling temperature is about 103 ° C, and this solution is discharged from a spinneret nozzle, and the obtained discharged yarn is cooled. The temperature of the cooling bath should be 40 ° C or lower.

Further, the depth, length, etc. of the cooling bath are not particularly limited, but when discharging as a multi-filament, it is sufficiently cooled in the cooling bath before the single fibers constituting the multi-filament are bundled. Therefore, the temperature, depth and length of the cooling bath should be appropriately set so that gelation is completed.

The gelled yarn thus obtained has a characteristic that the concentration of the polymer constituting the gelled yarn is substantially the same as the polymer concentration in the spinning dope, and this characteristic is the above-mentioned polymerization of the present invention. It is extremely important for forming high-strength, high-modulus fibers from PVA-based polymers in the range of degrees.

That is, having such characteristics, the obtained gelled yarn is at least 15 times, preferably 18 times or more by hot-drawing and then desolventizing treatment with water. Is an essential requirement for stretching.

The unstretched yarn thus obtained is hot-stretched (primarily stretched) before the desolvation treatment. In this case, the stretching temperature is PV.
The temperature may be 160 to 250 ° C., which is a temperature equal to or lower than the melting point of the A-based polymer, and either one-stage or multi-stage may be used.

In the present invention, when the gelled yarn is immediately stretched before the desolvation treatment, the stretching temperature is preferably set to a temperature not higher than the melting point of the PVA polymer gel. By heating and stretching the gelled yarn in a wet state before the desolvation treatment, and then desolvating the water, even if water is used for the desolvation treatment, the single fibers between the single fibers in the desolvation treatment and the subsequent drying step are Fusing can be substantially prevented, and a high-strength, high-modulus PVA-based multifilament yarn that is flexible and has excellent openability can be industrially produced advantageously. However, the stretching temperature of the gel-like yarn varies depending on the gelling temperature of the spinning dope, but the gelling temperature of the spinning dope is 110 to 120 ° C, for example.
In the vicinity, when stretched at room temperature, the stretchability is low, and it is possible to stretch only at most about 2 times, and it is not heat set after stretching and shrinks. Therefore, in this case, the polymer chains constituting the fiber are sufficiently oriented, and the crystallized fiber structure and
To make a fiber yarn with sufficient water resistance, 60 to 11
It is preferable to stretch in the range of 0 ° C.

The stretching device may be any means such as a heating tube, a heating plate, a heating roller, a heating pin, a heating liquid bath, and a fluidized bed, and is not particularly limited.

The desolvation treatment is performed by hot drawing the gelled yarn and then using water to remove the solvent.

The yarn after the desolvation treatment is heated and dried, and the water contained in the yarn used for the desolvation treatment is removed.

The desolvation treatment of the yarn stretched in the wet gel state uses water as a solvent and is industrially advantageous as described above, but the desolvation treatment conditions in this case are:
Although it depends on the degree of polymerization of the PVA-based polymer that constitutes the fiber, the tacticity, etc., it is a condition that does not cause fusion between the single yarns of the drawn yarns and has good desolvation efficiency, preferably normal.
The treatment may be performed within the temperature range of 10 to 50 ° C.

The drawn / desolvated yarn thus obtained is dried,
In this case, in order to alleviate the fusion between single yarns, reduce the friction resistance with the metal in the subsequent post-treatment process, and suppress the spread of the single yarns due to static electricity, it is treated with various oil agents and dried. Good. As the drying means, a known heating drum, heating tube, hot air, or the like can be adopted.

The dried drawn yarn, using the heating tube, hot plate, heating roll, heating pin, heating liquid, fluidized bed, etc.,
Secondary stretching is performed in a temperature range of 100 to 250 ° C. in a single step or in a plurality of steps, and the resulting yarn is stretched so that the total draw ratio is at least 15 times, preferably 18 to 30 times. This total draw ratio is an important requirement for highly orienting the polymer chains constituting the PVA-based fiber yarn of the present invention in the fiber axis direction and highly increasing the strength and elastic modulus thereof. It is possible to obtain excellent fibers having a tensile strength of 18 g / d or more and a tensile elastic modulus of 350 g / d or more.

[Operation and Effect of the Invention] According to the present invention, a PVA-based fiber having an extremely high mechanical strength can be produced using a commercially available polymer having a polymerization degree of 2000 to 6000 as a PVA-based polymer. .

Tensile strength of at least 18g / from PVA polymer with the above degree of polymerization
We have succeeded in obtaining fibers with excellent physical properties such as d and an elastic modulus of 350 g / d or more, because the spinning stock solution of PVA-based polymer is a stable solution of PVA-based polymer solution with a concentration range with good spinnability. And found that by making the polymer concentration of the gelled yarn obtained from this spinning dope substantially the same as the polymer concentration of the spinning dope, the extensibility of the obtained gelled yarn is highly improved. When heat-treating a wet gelling yarn, water is used as a solvent for the desolvation treatment, and it is possible to use a flammable and toxic solvent such as conventional methanol. There is a merit that it is good, and it is not only that water is cheap, but also the significance as an established industrial production method of the ultrahigh strength PVA fiber of the present invention is extremely significant.

Further, according to the present invention, various kinds of fibers such as multifilaments having a total fineness of about 100 to 10,000 d can be easily produced from monofilaments.

Hereinafter, the present invention will be specifically described with reference to examples. In addition,
In the examples, the physical properties of the fibers are values measured under the following conditions.

Measurement sample: Single yarn Measurement test length: 100 mm Tensile speed during measurement: 100 m / min Measurement atmosphere: 20 ° C, 65% relative humidity Example 1 Polymerization degree 2100 (molecular weight conversion 9240,000), saponification degree 99.5%
PVA was dissolved at 170 ° C. using glycerin as a solvent to prepare a spinning dope having a polymer concentration of 17.5% by weight. This spinning solution
The temperature was maintained at 170 ° C., a spinning nozzle having a hole diameter of 0.08 mm and 10 holes was discharged into the air, and decalin at 15 ° C. 8 mm below the nozzle surface was introduced into a bath as a cooling liquid to cool. The total discharge amount of the spinning dope from the nozzle was 0.97 cc / min, and the cooled rubber-like gelled yarn was collected at 5 m / min.

The obtained gelled yarn was stretched 4.0 times in a heating tube having a length of 80 cm and an internal air temperature of 100 ° C., and wound on a plastic bobbin. The wound yarn together with the bobbin was repeatedly immersed in warm water at 40 ° C. to extract glycerin in the yarn. Next, the yarn was dried to remove water, and stretched 3.8 times and 4.5 times using a hot plate having a surface temperature of 230 ° C. Table 1 shows the physical properties of the drawn yarns having the total draw ratios of 15.2 times and 18 times, respectively.

Further, in these drawn yarns, fusion was not recognized between the single fibers at all, and the flexibility and openability were excellent.

Comparative Example 1 In the hot plate drawing after the desolvation treatment of Example 1, the draw ratio was changed to 1 (no more drawing), 2.0 and 2.7, and otherwise the same as in Example 1 to prepare a drawn yarn. did. The physical properties of the obtained fiber yarn are shown in Table 1.

As can be seen from the table, if the total draw ratio is lower than 15 times,
It can be seen that the physical properties of the obtained fiber yarn are significantly reduced.

Example 2 Polymerization degree 3900 (molecular weight conversion 172,000), saponification degree 99.6%
PVA was dissolved at 170 ° C using glycerin as a solvent to give a concentration of 11.0
A wt% spinning dope was prepared.

This spinning solution is maintained at 170 ° C and discharged into the air from a spinning nozzle with a hole diameter of 0.06 mm and 20 holes, 10 mm below the nozzle surface.
The discharged yarn was gelated by introducing it into a cooling bath containing decalin at 15 ° C as a cooling liquid. The total discharge amount of the spinning dope from the nozzle was 0.97 cc / min, and the cooled rubber-like gelled yarn was collected at 2 m / min.

The obtained gelled yarn was stretched 4.0 times in a heating tube having a length of 80 cm and an internal air temperature of 100 ° C., and wound on a plastic bobbin. Each wound bobbin was repeatedly immersed in warm water at 40 ° C for each bobbin to extract the solvent in the bobbin. Next, the yarn was dried to remove water, and further stretched 5.5 times using a hot plate having a surface temperature of 230 ° C.

The resulting fiber yarn having a total draw ratio of 22 times is a multi-filament yarn in which the single yarn fibers without fusion between single yarns are 1.54d, and the strength is 20.1 g / d, the elongation is 4.9%, and the elastic modulus is 430 g / It exhibited excellent physical properties of d.

Comparative Example 2 In Example 2, the gelled yarn obtained by discharging the spinning dope from the nozzle and cooling was immediately immersed repeatedly in warm water at 40 ° C. to extract the solvent without stretching with a heating tube. When dried, a yarn with remarkable fusion between single yarns was formed, and as a result of stretching this yarn using a hot plate at 230 ° C., the maximum draw ratio was 15 times in total draw ratio and Stretching was difficult. In addition, the obtained yarn,
The fusion was remarkable, it was brittle and lacked in openability, and the physical properties of the multifilament yarn were measured.
It showed low fiber physical properties such as g / d and elastic modulus of 327 g / d.

Example 3 In Example 1, ethylene glycol was used as a solvent for the polymer, and the same conditions were applied except that the total draw ratio was 16 times, the strength was 18.3 g / d, and the elastic modulus was 384 g / d. A yarn having good openability without fusion was obtained.

Comparative Example 3 PVA having a polymer polymerization degree of 1300 (molecular weight conversion: 572,000) and a saponification degree of 99.5% was dissolved in glycerin at 160 ° C to prepare a spinning dope having a concentration of 20% by weight. The obtained spinning dope was spun, gelled and stretched in the same manner as in Example 2 (with a draw ratio of 4
Fold), desolvation treatment, drying, and biaxial stretching (however, stretching was 4.8 times using a hot plate at 230 ° C).

The total draw ratio of the obtained yarn was 19.2, but the fiber properties were a strength of 13.5 g / d, an elongation of 6.1% and an elastic modulus of 354 g / d.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-100710 (JP, A) JP-A-59-130314 (JP, A) JP-A-55-107506 (JP, A) JP-B-44- 26409 (JP, B1)

Claims (1)

[Claims] 1. A polyvinyl alcohol-based polymer solution having a degree of polymerization of 2000 or more and 6000 or less, the melting point of the polymer is 80 ° C. or less.
It was a solvent that was soluble at the above temperatures and was soluble in a solvent that was miscible with water, and this solution was discharged from the spinneret hole as a spinning stock solution, and the discharged yarn was kept below its gelling temperature. After introducing into a cooling bath that is immiscible with the solvent of the spinning dope to form a gelled yarn, the resulting gelled yarn is hot-stretched at a temperature below its melting point, and then water is added. Desolvation treatment using, followed by drying, further secondary stretching,
A method for producing high-strength, high-modulus polyvinyl alcohol-based fibers, characterized in that a drawn yarn having a total draw ratio of at least 15 and free from fusion between single fibers.