JPS62125010A - High tenacity and high modulus pva fiber and production thereof - Google Patents

Abstract

PURPOSE:To easily obtain the titled PVA fiber having excellent handle-ability, by adding an additive consisting of a specific polyvinyl compound to a PVA polymer, spinning the obtained spinning dope and drawing the spun fiber at a high draw ratio. CONSTITUTION:A PVA polymer having an average polymerization degree of >=1,500 is dissolved in a solvent such as ethylene glycol together with a polyvinyl compound having a copolymerized ethylene unit content of 15-85mol%. The amount of the polyvinyl compound is 0.5-10wt% based on the PVA polymer. The mixture is stirred to obtain a viscous spinning dope. The spinning dope is spun by conventional method, most part of the solvent is removed from the spun fiber and the fiber is drawn at a high draw ratio to obtain the objective fiber having a tensile strength of >=15g/d and a tensile modulus of >=400g/d.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides high strength and high modulus polyvinyl alcohol (
In this specification, it is abbreviated as PVA, and the same may be abbreviated below), and its production method.In particular, it suppresses swelling in water and adhesion between fibers, and improves handleability. The aim is to obtain high-strength, high-modulus PVA fibers that can be passed through industrial materials.

<Prior Art> Conventional PVA fibers have a higher strength modulus than polyamides, polyesters, polyacrylonitrile-based M fibers, and fibers, and are used for industrial materials and reinforcing materials such as cement.

However, the PVA fibers obtained so far do not have the strength and modulus of aromatic polyamide (aramid) fibers or ultra-high molecular weight polyethylene fibers.

PVA fibers are usually produced by a method in which a PVA aqueous solution is turned into a spinning i-liquid, wet-spun in a coagulable inorganic salt water bath, and subjected to stretching, drying, heat treatment, or acetalization treatment for water resistance. Various methods have been proposed to improve the strength and elastic modulus of this PVA fiber.

For example, in Special Publication No. 43-16675, P”/A
A method of wet spinning a dimethyl sulfoxide (hereinafter abbreviated as DMSQ) solution in an organic solvent such as methanol, ethanol, benzene, or chloroform as a spinning stock solution is described in JP-A-56-128309. A method has been proposed in which PVA@fibers are stretched at least 10 times or more and then heat treated.

Also, Special Publication No. 37-14422 and Special Publication No. 47-32
No. 142 describes PV containing boric acid or borate.
A method is disclosed in which an aqueous solution of A is spun into an alkaline coagulation bath containing Dandan no Hanawa to crosslink boric acid to PVA, and then the boric acid or its crosslinked product is removed again. However, the strength of PVA* fibers obtained by these methods is 12 f
/d or less, the modulus was 4001/(1 or less).

On the other hand, in JP-A No. 60-126312, the degree of polymerization of PVA is about 4000, the total draw ratio is about 30 times, the strength is 20y/c1r,
A PVA fiber with a modulus of 450 f/dr is disclosed;
JP-A-59-130314 discloses that gel fibers are prepared by cooling using glycerin or ethylene glycol as a solvent, and are stretched to have a strength of 19 f/dr.

A method for obtaining PVA fibers with a modulus of 500 to 600 P/dr has been shown, but as in the present invention, it is easy to obtain PVA fibers with a strength of 201 P/dr.
/dr or more, it was difficult to exceed the modulus of 500y/dr or more, and it was difficult to suppress swelling in water and adhesion between fibers.

1+ Japanese Patent Publication No. 47-42057 discloses that polyvinyl chloride PVA is mixed and emulsion spun to improve water resistance. Co-emperor union and P, V A
It has been shown that fibers obtained by emulsion spinning are flexible and have low tensile strength and are suitable for paper or nonwoven fabrics. There is no mention of obtaining fibers that are

There is also a known method of adding weight to inorganic fine particles such as silica sol to prevent stiction of the lintel, but in this case, there is a risk that the inorganic fine particles will inhibit the stretching, and high-magnification stretching is difficult.

<Problems to be Solved by the Invention> Based on the above background, the present inventors aimed to highly orient R fiber molecules by high-strength stretching and It was considered necessary to carry out crystallization to prevent the acid phase.

In the process of drawing PVAMl fibers at a high magnification, large deformations occur in which the crystals generated during spinning are destroyed and rearranged, but one way to facilitate this deformation is to add a third component other than PVA and a solvent. Disturbing the crystals of the spun filament and suppressing intermolecular water-violet bonds, and reducing the number of defects at the end of the molecular chain and adding 2 to the low concentration PVA'f&solution.
The aim of this study was to reduce the entanglement of molecular chains. It was considered desirable that the additive contained in the third component be one that softens or melts during stretching and does not interfere with the stretching of the PVA@fiber.

On the other hand, when extracting and removing the PVA yarn weaving agent, a solvent containing methanol or acetone or water is generally used, but especially when cheap water is used, the PVA fibers swell and stretch. This tends to deteriorate process passability, and also induces aggregation between fibers, resulting in decreased workability and stretchability. Furthermore, when the obtained drawn yarn is used in water, swelling and sticking occur easily, and PVA fibers with good handling properties have been desired. As a result, it was found that day-strength, high-modulus PVA [fibers] with excellent handling properties can be easily obtained.

Means for Solving the Problems〉 That is, the present invention provides ``(1) an additive consisting of a polyvinyl compound with an ethylene copolymerization rate of 15 to 85 mol in polyvinyl alcohol fibers with an average degree of polymerization of 1500 or more. 0.5~10
Contains Wataruchi, and the tensile strength of η single fiber is 15 t/C
1r or more, tensile modulus is 400? /dr or more, high strength, high modulus PVA fiber (2) Average degree of polymerization is 6000 or more, single fiber tensile strength is 20f/dr or more, and tensile modulus is 500f/d
The high-strength, high-modulus PVA fiber according to claim 1, which has a strength of R or more.

(8) Claims 1 and 2, wherein the polyvinyl compound of the additive is a polyvinyl alcohol compound with a degree of saponification of 90 molar or more, a melting point of 200°C or less, and an average degree of polymerization of 50 to 2000. The high tenacity, high modulus PVA fiber described in Section 1.

(4) When dissolving a polyvinyl alcohol polymer having an average degree of polymerization of at least 1500 or more in a solvent, add an additive consisting of a polyvinyl compound having an ethylene copolymerization rate of 15 to 85 molti to the polyvinyl alcohol polymer. ．．
5-10. 0 (5) A method for producing a high-strength, high-modulus PVA-based fiber, which is characterized in that the fibers are mixed under stirring, then spun using a conventional method, most of the solvent is removed, and then stretched to a high magnification. 5. The method for producing a high strength flat modulus PVA fiber according to claim 4, wherein the average degree of polymerization is 6000 or more.

(6) The polyvinyl compound of the additive is a polyvinyl alcohol compound sb with a degree of saponification of 90 molar or more, a melting point of 200°C or less, and an average degree of polymerization of 50 to 2000. The method for producing a simple and strong high modulus PVA fiber according to item 5 (7) Stretching polyvinyl alcohol-based spun yarn having a solvent content of 20% or less under dry heat at 200 to 240°C at least 5 times or more. 6. A method for producing a high-strength, high-modulus PVA-based fiber according to claims 4 to 6, characterized in that the fiber is drawn at a total stretching ratio of 15 times or more.

The contents of the present invention will be explained in more detail below.

The pVA-based polymer referred to in the present invention refers to the viscosity of an aqueous solution at 30°C. It is a linear polyvinyl alcohol with an average degree of polymerization of 1,500 or more as determined by the polymerization method, and a saponification degree of 98 mol or more and a low degree of branching.

In addition, other vinyl compounds of 2 molar or less (e.g., phon group,
It also includes those copolymerized with compounds represented by alkyl ester groups, carboxyl groups, etc.), as well as those with additions of 3% by weight or less of pigments, antioxidants, ultraviolet absorbers, other modifiers, etc.

The higher the average polymerization degree of PVA, the greater the possibility of obtaining high strength and high modulus fibers, preferably 6000 or higher,
More preferably, it is 10,000 or more, and it is desirable to reduce the entanglement of molecular chains by setting the PVA concentration to 15 parts by weight or less, preferably 10 parts by weight or less, and even more preferably 5 parts by weight or less.

Solvents for dissolving PVA include ethylene glycol,
Polyhydric alcohols such as trimethylene glycol, diethylene glycol, and glycerin, dimethyl sulfoxide, dimethyl formamide, diethylene triamine,
Further, a mixed solvent of two or more of these solvents with f1 alcohol or an aqueous Rodan salt solution may be used, but the ethylene copolymerization rate as referred to in the present invention is 1.
A solvent that dissolves or uniformly disperses a polyvinyl compound with an ethylene copolymerization rate of 15 to 85 molti is particularly preferable.A polyvinyl compound with an ethylene copolymerization rate of 15 to 85 molti dissolves or disperses uniformly in a mixed solution of a solvent and PVA. To,
It is desirable that PVA be added in the form of a dispersion before being dissolved in a solvent. The additive is preferably dissolved in the PVA solution, but may also be dispersed in the form of fine particles of 10 μm or less, preferably 1 μm or less.

The feature of the present invention is that the additive disturbs the crystals of PVA and melts or softens during stretching, increasing the stretching ratio without inhibiting stretchability, and suppresses swelling and sticking to water. Ruru points. Therefore, an additive that satisfies the above points has an ethylene copolymerization rate of 15 to 85 molt, preferably 3.
If it is between 0 and 50 molty, it is good, and if it is less than 15 molty, it is not possible to sufficiently suppress the crystallization of PVA and the suppression of intermolecular hydrogen bonds that interfere with stretching, and furthermore, the handling properties in water are slightly improved. 0 If the ethylene copolymerization rate exceeds 85 molt, PVa and PVA become incompatible with the solvent, and it is difficult to uniformly disperse KO, which tends to cause yarn breakage and fuzz during spinning and drawing. 0 In the present invention, in the polyvinyl compound, B represents a hydroxyl group, a formate ester group, an acetate ester group, a propionate ester group, or a chlorine or cyanide group, and it does not matter whether they are the same or different. m% n is a positive number, and the m/n ratio may take any value. In addition, from the viewpoint of compatibility with PVA, poly and nylalco-It/based compounds having a degree of saponification of 90 molti or more are preferred. Ethylene may be copolymerized by block copolymerization or random copolymerization, but random copolymerization is preferable for the purpose of suppressing the silium hydrogen bonds that disrupt the crystals of Ruru PVA, which is a feature of the present invention.

Furthermore, it is preferable that the additive melts in a bath during dry heat stretching at 200°C or higher, so it is preferable that the additive has a melting point of 200°C or lower. In consideration of change and stretchability, those having a melting point of 80 to 180°C are particularly preferred.

In addition, the additives must be dissolved or uniformly dispersed in the PVA bath liquid, and the particle size of the additives must be as small as possible (in PVA14Q fibers, particles of 1 μm or less are dispersed). This is preferable because of this homogeneous dispersion and the bleedability of the additive during use (drying, washing, etc.
The average degree of polymerization of the additive is preferably from 50 to 2,000 in terms of the property of the VA fiber coming out from the inside to the surface) and shedding.

The amount of the additive added is 0.5 to 10% relative to the PVA polymer.
1i%, preferably 1-611. If the amount added is less than 0.5% by weight, the effect of the additive referred to in the present invention will be small, and high-strength stretching and high-performance PVAN1. If the amount of Q added exceeds 10'N, which makes it difficult to obtain a dark blue color, it will not only inhibit the properties of the PVA fiber and reduce the heat resistance and shape stability, but also adversely affect the drawability. This is not preferable because it may have a negative effect.

Regarding the preparation of the spinning stock solution, it is sufficient to add the PVA solvent and additives, as well as other compounds such as antioxidants as necessary, and turn the dispersion of P'il'A into a high viscosity solution under heating and stirring. As far as obtaining the spinning dope is concerned, the dissolution method can be either batch or continuous.

The spinning methods include conventional wet spinning, dry spinning, dry-wet spinning,
There is no problem if you use a method suitable for the solvent such as gel spinning, but
Gel spinning, which becomes gelatinous upon cooling, is desirable from the standpoint of circumscribing the entanglements of PVA molecular chains and facilitating stretching at different magnifications. Generally, solvents such as polyhydric alcohols or mixtures of dimethyl sulfoxide and water are used for gel spinning, but it is also possible to use other solvents such as dimethyl sulfoxide or an aqueous solution of Rodan's salt by the gelling method. can.

The yarn discharged from the nozzle contains a large amount of solvent, and it is necessary to remove the solvent in order to maintain the shape stability, prevent sticking, and stretchability of the spun yarn.

Solvent removal methods include extraction methods using extractants such as water, methanol, ethanol, acetone, coagulation and extraction agents in inorganic salt water baths, and evaporation removal methods by drying. It is preferable to use a method that extracts the liquid in a dry manner. Note that after extraction, there is no problem even if a drying treatment is performed to remove the adhering extractant. When washing with water and soaking in solvent, PVA fibers tend to swell and elongate.
It also tends to dissolve a little, making it difficult to handle more.
If the uninvented additive 11 is used, the above problems will hardly occur, and the F! jIt reduces the problem of I deposition and significantly improves process passability.

Solvent-containing f1 has 100iJi for PVAR fiber 1/C.
% or less, preferably 20 wt.

Regarding stretching, it is possible to use wet heat or dry heat to draw the yarn if necessary in the spinning process, but dry heat drawing at a high temperature is recommended in terms of the same drawing ratio as above and the molecular chain orientation and crystallinity of the resulting drawn yarn. ○ The heater for dry heat stretching requires a non-contact tie 1. In order to prevent the additives from softening or melting and completely inhibiting the stretchability, a high temperature of 200 to 240°C is required. preferable.

In addition, to obtain high-strength, high-modulus PVA [(Ih), it must be stretched at least 5 times or more, preferably 10 times or more, by pan hot dry heat stretching, and the total stretching ratio including the stretching ratio during spinning must be 15 times or more. , preferably 20 times or more.

The PVA fiber obtained by the invention has a single meter tensile strength of 15 f/dr or more and a tensile modulus of 400 f/dr.
dr or higher, especially if the average degree of polymerization of PVA is 6000 or higher, the tensile strength is 20 f/dr or higher and the tensile modulus is 50.
The present invention has produced a high-strength pigeon for industrial materials that exhibits a value of 0j'/ar or more, and has little change in form due to swelling in water or sticking during long-term use, and has unprecedented ease of handling. It was possible to obtain modulus PVA fiber.

The present invention will be specifically explained below using Examples.

Actual mN1-4 and Comparative Example 1 Average degree of polymerization is 1700, 3400.7000 and 12
Complete saponification of 000? Using VA and ethylene glycol as a solvent, saponified and 100 mol of polyvinyl alcohol compound (polymerized and 700, melting point 157°C) with an ethylene copolymerization rate of 48 mol as an additive, and 165 with an antioxidant of 0.5 wt/PV a. The mixture was stirred and mixed at ℃ for 3 hours to prepare a spinning stock solution with a controlled viscosity. The PVA strength varies depending on the degree of polymerization and is as shown in Table 1, and the additives used were 3 times higher than the PVA in each case.

After degassing the dissolved stock solution, the denier of the spun yarn was 30.
The stock solution was discharged through a single-hole nozzle using Gear Bonn 1 at a concentration of 0 clrK, and cooled in air to form a gel. The spinning draft at this time was 1.2 to 1.6.

Subsequently, the Glue fJR fiber was passed through water in the first bath and methanol in the second bath to remove much of the solvent, and then the water and methanol were evaporated across the spinning yarn using hot air at 80°C and transferred to the bobbin. I took it.

The obtained spun yarn was drawn with a hollow heater at 235° C., and the results shown in Table 1 were obtained. However, as Comparative Example 1, the results without the additive are also shown.

In Examples 1 to 4, all of the spinning stock solutions were filtered as homogeneous transparent liquids at 160°C, and the additives were completely dissolved. When ethylene glycol and the additive were stirred at 160°C for 10 minutes, the additive dissolved into #I and became a transparent liquid, but when the liquid was cooled to 100°C, the entire liquid became cloudy.

Kelization (solidification) during spinning is faster than without additives,
There was no fuzz or yarn breakage, and the spinning condition was good.

In any of Examples 1 to 4, R1 in water of the first bath,
There is almost no swelling or elongation of the fibers, and even if the elongation rate between the first and second baths is as low as 2 to 5%, there is no sagging of the fibers, and the fibers have a nearly circular cross section. was gotten. The residual ratio of #1 agent in the spun yarn after winding was as low as 2 to 3 wt %, and the total stretching ratio was 16 times or more after dry heat stretching at 0235°C, where no dotting of the yarn was observed. , strength 17-22r/dr
1-v-jurus 425-600 f/dr. The higher the degree of polymerization of Nas, -PVA, the higher the draw ratio and fiber performance. Furthermore, the obtained drawn yarn was
Although it was immersed in daylight water, there was almost no swelling, and there was no sticking during subsequent air drying, and the shape stability and handling properties were clearly superior to those of Comparative Example 1 without additives.

The present invention provides high-strength, high-modulus PvAM1 with unprecedented handling properties. fiber was obtained.

In Comparative Example 1, no additive was used, but the swelling and elongation in the first bath during spinning was large, and the elongation was set to 20% and wound up.

Although the solvent residual rate was as low as 3.7%, sticking of the yarn was observed, and the drawing ratio and fiber performance were lower than in the case of the additive female.

Example 5 Completely saponified PVA with an average degree of polymerization of 7000 was used at a concentration of 7w
At the same time, a polyvinyl acetate compound having an ethylene copolymerization rate of 31 molt was added in an amount of 6 wt%/PVA, and the mixture was stirred and dissolved at 70°C. The obtained stock solution was filtered to make it a homogeneous transparent liquid, and it was
Using a hole nozzle, methanol/L) MS O=
The raw yarn was wound up by wet spinning and discharged into a 90/10 coagulation bath. Note that no elongation was performed during spinning. The residual solvent content of the obtained raw yarn was as high as 89%, and in order to further remove the solvent, the bobbin-wound raw yarn was immersed in methanol/water = 1/1 for 3 days and then vacuum-dried at 100°C for 24 hours to remove the solvent. The rate was set at 0.7 yen. There was almost no swelling of the yarn in the methanol/water ratio of 1/1, and no sticking was observed after vacuum drying.

The raw yarn after vacuum drying was stretched in two stages using two hollow heaters at 190°C to 210°C to obtain a drawn yarn with a total stretching ratio of 20.5 times. The strength of the single fiber of the drawn yarn is 21.4t/drs
The modulus was 532f/dr, and it was possible to easily obtain a PVAR fiber with high strength and high modulus.Example 6 Completely saponified PVA with an average degree of polymerization of 3400 and a concentration of 14
Disperse in a solvent of Rondan soda/water: 1/1 so that the weight ratio is 1/1, and at the same time, a polyvinyl alcohol compound with a particle size of 10 μ or less, an ethylene copolymerization rate of 70 mol, a saponification degree of 80 mol, and an acetylation degree of 20 mol. 1.5 wt%/P
VA was added and the PvA was dissolved at 0°C.

Although the additive was not dissolved in the stock solution and was uniformly dispersed in the form of particles, there was no hair trimming during spinning, and a monofilament yarn with a uniform C width was obtained.

Spinning is a wet-dry process, with the nozzle placed in a methanol bath at 30°C.
The nests were separated and gelled by rapid cooling.

The gel fiber was stretched twice in methanol at room temperature, dried with hot air at 90°C, and then rolled up, but the solvent residual rate was 15.8%. Furthermore, to remove the solvent, the bobbin winding yarn is washed with water 1.
The fibers were immersed in methanol for 1 day and vacuum dried at 90°C for 1 day to give a solvent residual rate of 1.2%, but no swelling or sticking f'i of the fibers was observed during this period.

The obtained yarn was dry-heat stretched at 220°C to give a total stretching ratio of 18.6 times, but the strength of the drawn yarn was 18.4 f/
dr, modulus is 477f/dr and 6 points 0

Claims (7)

[Claims] (1) Polyvinyl alcohol fibers with an average degree of polymerization of 1,500 or more, containing 0.5 to 10% by weight of an additive consisting of a polyvinyl compound with an ethylene copolymerization rate of 15 to 85 mol%, and the tensile strength of single fibers A high-strength, high-modulus PVA fiber having a tensile modulus of 15 g/dr or more and a tensile modulus of 400 g/dr or more. (2) The average degree of polymerization is 6000 or more, the tensile strength of the single fiber is 20 g/dr or more, and the tensile modulus is 500 g/d.
The high-strength, high-modulus PVA fiber according to claim 1, which has a molecular weight of r or more. (3) Saponification degree of polyvinyl compound as additive is 90 mol%
The high-strength, high-modulus PVA-based fiber according to claims 1 and 2, which is the polyvinyl alcohol-based compound described above, has a melting point of 200° C. or less, and an average degree of polymerization of 50 to 2,000. (4) When dissolving a polyvinyl alcohol polymer with an average degree of polymerization of at least 1500 or more in a solvent, add an additive consisting of a polyvinyl compound with an ethylene copolymerization rate of 15 to 85 mol% to the polyvinyl alcohol polymer. .5
A method for producing a high-strength, high-modulus PVA-based fiber, which comprises adding ~10% by weight, mixing under stirring, spinning by a conventional method, removing most of the solvent, and then drawing to a high ratio. (5) The method for producing a high-strength, high-modulus PVA-based fiber according to claim 4, wherein the average degree of polymerization is 6,000 or more. (6) Claim 4, wherein the polyvinyl compound as an additive is a polyvinyl alcohol compound with a degree of saponification of 90 mol% or more, a melting point of 200°C or less, and an average degree of polymerization of 50 to 2000; 6. The method for producing a high strength, high modulus PVA fiber according to item 5. (7) Polyvinyl alcohol-based spun yarn with a solvent content of 20% by weight or less is stretched at least 5 times or more under dry heat at 200 to 240°C, and the total stretching ratio is 15 times or more. A method for producing a high-strength, high-modulus PVA-based fiber according to claims 4 to 6.