JP2858925B2 - Method for producing hot water-resistant polyvinyl alcohol fiber - Google Patents

Description

The present invention relates to a polyvinyl alcohol (hereinafter abbreviated as PVA) fiber having high strength and excellent hot water resistance, particularly for industrial materials and The present invention relates to a PVA-based fiber suitable for use in reinforcing composite materials and requiring hot water resistance.

(Prior art) Conventional PVA fiber has higher strength and elastic modulus than polyamide polyester and polyacrylonitrile fiber, and is used as a substitute for asbestos fiber for cement reinforcement in addition to being used as industrial material fiber, which is its main use. It has also been used for fibers and the like.

In recent technology, JP-A-59-100710, JP-A-59-130314, and JP-A-59-130314, which apply the concept of gel spinning and ultra-drawing of high molecular weight polystyrene as a method for obtaining a PVA-based fiber having a higher strength elastic modulus. Japanese Utility Model Application Laid-Open No. 61-108711 has been proposed.

However, in these methods, high-strength, high-modulus PV
Even if the A-based fiber is obtained, it cannot have high hot water resistance required in some application fields.

Attempts to increase the hot water resistance of PVA fibers have long begun with water insolubilization treatment by acetalization.However, in recent high-polymerization and high-strength PVA fibers, the molecular orientation of the amorphous part has progressed, and the dimensional stability to water is poor. This can be achieved without performing the water insolubilization treatment described above. However, it is still unsatisfactory for applications such as reinforcing materials for cement molded products for autoclave curing and ropes that are susceptible to frictional heat, for example, which melts quickly in hot water at 120 ° C.

Further, as seen in JP-A-1-156517 and JP-A-1-207435, or JP-A-1-048815 and JP-A-2-84587, a peroxide compound, an isocyanate compound or boric acid or A method for improving the hot water resistance by performing a crosslinking treatment with phosphoric acid or the like is known. However, when these methods are crosslinked before stretching, the stretchability is impaired, and the molecular orientation is insufficient, so that the strength and the elastic modulus are reduced. On the other hand, if it is attempted to crosslink after stretching, it is necessary to swell the fiber or to perform high-temperature heat treatment in order to strengthen the penetration of the crosslinking agent into the fiber, resulting in disordered molecular orientation, decomposition and damage of PVA, and strength. There is a problem that the elastic modulus tends to decrease.

(Problems to be solved by the invention) Based on the above background, the present invention has a tensile strength of 16 g / d.
It is intended to obtain a PVA-based fiber having a high strength and a high elastic modulus as described above, and having excellent hot water resistance so as to be able to withstand an autoclave. It is intended to obtain the above-mentioned high-performance fiber without lowering the fiber. Further, the present invention is not intended to realize such a fiber in a short and simple processing step, instead of being obtained by performing a long and special processing step.

(Means for Solving the Problems) As a result of examining the above problems, the present inventors have found that an appropriate amount of a certain oil agent is applied and then drawn at a high temperature to react with hydroxyl groups of PVA on the fiber surface or to cause a dehydration reaction. It has been found that it is effective to cause a hot water-resistant skin structure by causing the heat treatment.

That is, the present invention relates to a PVA-based fiber having a viscosity-average degree of polymerization of 3,000 or more, from spinning to immediately before drawing, a phosphate amine compound,
One or two or more surfactants selected from amine or amide phosphate compounds, amine or amide sulfonate compounds and thio compounds, and 0.2 to 3% by weight of an ester or mineral oil-based focusing and leveling agent 0.5 to 5% by weight and stretched at a high temperature of 240 ° C. or more so that the total draw ratio becomes 17 times or more. Manufacturing method.

WTb ≧ 1.2A ^0.35 +125 (A ≧ 3,000) ”.

 Hereinafter, the present invention will be described in detail.

The PVA-based polymer used in the present invention has a viscosity average degree of polymerization of 3,000 or more determined from the intrinsic viscosity of an aqueous solution at 30 ° C.,
It is preferably 6,000 or more, more preferably 10,000 or more, and is preferably a linear PVA having a degree of saponification of 98 mol% or more and a low degree of branching. It is also possible to add a copolymer of 2 mol% or less of another vinyl compound or 3 wt% or less of additives such as boric acid, an antioxidant and an ultraviolet absorber.

The higher the degree of polymerization of PVA, the stronger the tie molecules that connect the crystals, and the higher the strength and hot water resistance.However, the higher the degree of polymerization, the more the molecular chains are entangled, and the more the molecular movement becomes active at higher temperatures. It is necessary to stretch it. As a result, the surfactant used in the present invention reacts with the hydroxyl group of PVA on the fiber surface or causes a dehydration reaction of PVA to easily form a skin structure having heat-resistant water. Therefore, when the degree of polymerization is less than 3,000, the stretching temperature is low and the effect is hard to appear. The effects of the present invention, such as high temperature stretching, are exhibited at a high degree of polymerization.

As the solvent for the PVA-based polymer used in the present invention,
Examples thereof include polyhydric alcohols such as ethylene glycol, trimethylene glycol, diethylene glycol, and glycerin, dimethyl sulfoxide, dimethylformamide, diethylene triamine, water, and a mixed system of two or more of these, or a rodane salt aqueous solution and a propanol aqueous solution. Among these, polyhydric alcohol, dimethyl sulfoxide, and a mixed solvent thereof with water are preferable for obtaining transparent and uniform gel fibers.

The spinning method may be any of a dry method, a wet method, and a dry-wet method, which are usually used, but dry-wet spinning for obtaining uniform gel fibers by quenching is desirable.

The coagulation bath does not interfere with alcohol such as methanol or ethanol, acetone, or an aqueous solution of an inorganic salt such as alkali and / or sodium sulfate. Suitable for obtaining performance fibers. To cause uniform gelation, the coagulation bath contains 10% by weight or more of the solvent,
It is preferable to extract the solvent slowly by quenching at a temperature of not more than ℃. Next, the wet drawing in a state containing the solvent is preferably performed at least twice, preferably at least four times, thereby reducing the sticking between the fibers and partially breaking the microcrystals generated at the beginning of spinning, and Stretching can be facilitated.

Subsequently, almost all of the solvent is removed with an extracting agent such as alcohols such as methanol and ethanol or acetone and water.At this time, the surfactant and the convergence smoothing agent according to the present invention are added to the extraction bath, There is no problem even if it adheres to the fiber, but it is not preferable that it penetrates into the fiber or causes adhesion spots.

There is no problem if the surfactant and the sizing smoothing agent are separately or simultaneously attached before drying after extraction, or attached immediately before drying and before hot drawing, but it is not necessary to attach them to the fiber in the form of an aqueous solution or water emulsion. Care must be taken because if the spun yarn is left undried, water will cause agglomeration between the fibers and the draw ratio or performance will be reduced.

The surfactant used in the present invention reacts with a hydroxyl group on the surface of the PVA fiber or causes a dehydration reaction, and is roughly classified into the following three.

(1) A phosphate amine compound.

For example, R-OP (O)-(ONR ₂ ) ₂ , (RO) ₂ -P (O) -NR ₂ , (RO) _2-
Anionic surfactants represented by P (O) -ORNR, RO (CH ₂ CH ₂ O) _n -P (O) -O-NR _{2 and the} like. In the formula, R is, for example, an alkyl group,
Examples include, but are not limited to, alkoxy, phenyl, phenol, H, and OH.

(2) Amine or amide phosphate compounds.

For example, R-NR-OP (O) -OR ₂ , R-CON-R-OP (O)-
Anionic activators such as OR ₂ R-N-CH ₂ -CONR-OP (O) -OR ₂ .

(3) Amine or amide sulfonate compounds and thio compounds.

For example, R-NR-SO ₃ M, R-CONR-SO ₃ Na, (R ₃ NO) ₂ -CH-RSO ₃ M, R
_{3 N-O-R-SO} 3 M, R-S-R-NR 2, R-S-R-CONR 2 anionic active agent represented by like.

In the formula, M represents H or an alkali metal salt. The convergence smoothing agent of the present invention is necessary for suppressing fluff breakage during stretching and enabling high-magnification stretching.For example, alkyl esters, sorbitan esters, castor oil esters, glycerin esters, glycol esters or their esters Ester nonionic activators, such as those having ethylene oxide added to the molecule, and mineral oils or ethylene oxide added thereto are also included.

It is preferable that the surfactant and the convergence smoothing agent are compatible with each other and adhere to the fiber uniformly, and therefore, other emulsifiers and penetrants may be used in small amounts.

The amount of the surfactant attached is 0.2 to 3% by weight with respect to the fiber,
Preferably it is 0.5 to 2% by weight, and if it is less than 0.2% by weight, the reaction with the OH group on the fiber surface or the dehydration reaction is insufficient, and it is difficult to obtain a fiber having good hot water resistance. If it exceeds 3% by weight, the heat resistance becomes high, but the draw ratio decreases, and only fibers with low strength can be obtained.

The amount of the bunched smoothing agent is 0.5 to 5% by weight based on the fiber;
Preferably, the content is 1 to 3% by weight, and if it is less than 0.5% by weight, the fibers are liable to be scattered, causing single yarn fluff and lowering the draw ratio. If it exceeds 5% by weight, the strength is lowered due to a slight tackiness, the reaction of the surfactant is inhibited, and smoke is generated during stretching, which is not preferable.

As a method of attachment, a solution diluted with alcohols such as methanol, acetone, hexane, water or the like or an emulsion liquid is attached to the fiber by a roller-touch method such as a dipping-nip method or a gear pump oiling method. Conditions for adhering are preferred.

When dry spinning the spun yarn to which a predetermined amount of the surfactant and the bunching smoothing agent are attached, the drawing temperature is set to 240 ° C. or higher,
The total stretching ratio needs to be 17 times or more. The reason for this is
This is because the reaction between the PVA hydroxyl group on the fiber surface and the surfactant is sufficiently performed, and the orientation and crystallization of the PVA molecular chain are advanced to obtain a fiber having high strength and excellent hot water resistance. The stretching atmosphere is generally considered to be air, an insoluble gas such as N ₂ , water vapor, an oil bath, etc., but heating air is suitable in consideration of the reactivity of the surfactant, operability, cost and the like. There are a contact type using a hot plate or a heating roller and a non-contact type using a hot blast stove. The higher the degree of polymerization, the more likely the entanglement of the molecular chains is, or the lower the draw ratio, and the higher the draw temperature, in order to cover the draw ratio. For example, polymerization degree 3,
The temperature is about 240 ° C. for 000, about 250 ° C. for 10,000, and about 260 ° C. for 20,000. However, the higher the temperature, the more easily the surfactant reacts to form a skin structure with hot water resistance. It is to be noted that staying at 265 ° C. or more or 1 minute or more is not preferable because PVA is greatly decomposed and the strength is reduced.

The total draw ratio is represented by the product of the wet draw ratio and the dry heat draw ratio, and is 17 times or more, preferably 19 times or more.

By performing fiber production in accordance with the production conditions described above, a high-strength fiber having a tensile strength of at least 16 g / d can be basically obtained. The combination of the agent and the treatment with the convergence smoothing agent results in a fiber having extremely excellent hot water resistance.

In general, the higher the degree of polymerization, the higher the thermal water-breaking temperature WTb of the PVA-based fiber. The higher the degree of polymerization, the higher the degree of polymerization.

WTb ≧ 1.2A ^0.35 +125 (A ≧ 3,000) That is, the fiber obtained by the present invention exhibits a hot water-breaking temperature higher by 10 to 50 ° C. than the conventional product at any degree of polymerization.

The present invention provides a PVA-based fiber having a high heat-resistant and high-strength property not found in the past, ropes, industrial materials such as canvas, an autoclave-cured cement reinforcement, a tire reinforcement, a high-temperature high-pressure hose reinforcement, a reinforcement for FRP, A wide range of applications such as brake oil hose reinforcement can be expected.

Hereinafter, the present invention will be described more specifically with reference to examples. The various physical properties in the examples described below were measured by the following methods.

1) Decrease in polymerization degree of PVA fiber Put PVA fiber and distilled water in a closed container, dissolve it at 130 ° C or higher, and then polymerize according to JISK-6726 [η] by the following formula according to [η].
And the rate of decrease with respect to the degree of polymerization of the PVA polymer is calculated.

A = ([η] × 10 ⁴ /8.29) ^1.63 2) Tensile strength and elongation, elastic modulus of yarn Yarn conditioned in advance according to JISL-1013 was tested at a test length of 20 cm.
The elongation at break and the initial elastic modulus were determined at an initial load of 0.25 g / d and a tensile speed of 50% / min, and an average value of 10 or more points was adopted. Denier was determined by the gravimetric method.

3) Hot water resistance (WTb) A load of 200 mg per denier is applied to 25 single fibers, suspended in the middle of a water-filled cylindrical glass container, and water is heated from the surroundings at a rate of 1-2 ° C / min. As the temperature was raised, the temperature at which the fiber was melted was read.

4) measuring the after weight W ₁ in which the vacuum drying 100 ° C. 4 h deposited fibers surfactant or adhesion rate previously surfactant or oils of oil. Then, the surfactant or oil was soxhlet extracted with a mixed solution of methanol / benzene = 1/1 for 8 hours, dried at 100 ° C. for 4 hours under vacuum, and the weight W ₂ was measured. It was calculated from:

Example 1 and Comparative Example 1 PVA having an average degree of polymerization of 21,500 was dissolved in glycerin so as to have a concentration of 4.2%, and the solution was discharged from a nozzle having a number of holes of 300 and a diameter of 0.20 mm. It was dropped into a coagulation bath at 8/2 at -10 ° C to obtain a transparent gel thread. Next, the film is stretched by a factor of 4 with glycerin in it, and the solvent is almost completely extracted with methanol. Then, 2% by weight of anionic surfactant lauryl phosphate triisopropanolamine and POE (20) sorbitan are added. A methanol solution containing 5% by weight of monostearate was attached to the fiber by 40% by weight using a gear pump oiling method, and 90%
Dry at ℃. 0.8% by weight of anionic activator and 2.0% by weight of sizing smoother were applied to the fibers. 1 spun yarn obtained
The film was stretched using a hot air oven at 70 ° C. and 260 ° C. so that the total stretching ratio was 17.9 times. The residence time in the hot-air stove at 260 ° C. was 32 seconds, and the fibers were colored gray-violet, but no sticking was observed.
From the photograph of the cross section of the obtained drawn yarn, only the surface layer of the fiber was gray purple and the inside was white. Yarn tensile strength is 21.2
g / d, hot water break temperature WTb is 182 ° C, a high strength fiber with excellent hot water resistance that cannot be obtained with conventional PVA fiber,
Cement reinforcement by autoclave curing at 0 ° C has become possible, and it has become a high-value-added fiber that can be used in a wide range of applications, such as high-temperature and high-humidity rubber reinforcements and rope fishing nets.

As Comparative Example 1, only the POE (20) sorbitan monostearate as a convergence smoothing agent was attached and stretched in the same manner as in Example 1 except that the surfactant was not added. Was. The total draw ratio is 18.6 times and the yarn strength is
It showed 20.8 g / d, and the WTb was found to be 152 ° C., and the hot water resistance was clearly lower than that of Example 1.

Example 2 and Comparative Example 2 PVA having an average degree of polymerization of 17,000 was dissolved in dimethyl sulfoxide so as to have a concentration of 4.5%, and methanol / dimethyloxide = 7/3, 5 ° C. with a nozzle having 500 holes and a hole diameter of 0.15 mm. Wet spinning was performed using a coagulation bath. Subsequently, the film was stretched by a factor of 4.5, and the solvent was almost completely removed with methanol.
It dried with the hot air of ° C. Then, 80% by weight of a methanol solution of 1.5% by weight of laurylamine thiodipropionate and 4% by weight of POE (150) Custerwax was attached to the fiber by a roller touch method (anionic surfactant 1.2%).
Wt% and a convergence smoothing agent of 3.2 wt%), 1.5 times in a 180 ° C hot air stove and 2.8 times in a 255 ° C hot stove (total stretching ratio of 18.9%).
Times) stretched. The residence time in the hot stove at 255 ° C was 38 seconds. The surface layer of the obtained drawn yarn was colored in ash brown, but had a yarn strength of 20.7 g / d and a WTb of 169 ° C., resulting in a PVA fiber having high strength and hot water resistance.

As Comparative Example 2, the stretching temperature was set to 255 ° C. in Example 2.
When the temperature was lowered to 235 ° C., the drawn yarn was hardly colored, and the total draw ratio was also reduced to 16.2 times. Yarn strength is 18.9g /
d, WTb was 149 ° C., which was clearly lower than that of Example 2.

Example 3 PVA having a viscosity average degree of polymerization of 7,000 was added to water so as to have a concentration of 8% by weight. At the same time, 2% by weight of boric acid was added to PVA and dissolved at 105 ° C. The resulting solution was placed in 1000 holes 0.1
The mixture was discharged into a mixed aqueous solution of alkali and sodium sulfate at 40 ° C. from a nozzle having a hole diameter of mm, and wet spinning was performed. Subsequently, the sheet was subjected to 5.3 times wet stretching, subsequently neutralized and washed with water, and then applied to the oil before drying by a roller touch method. The oil was 2% by weight of an anionic surfactant of sodium stearylamidopropylsulfonate, 3% by weight of glycerin trioleate and POE (1%).
1) It was a water emulsion solution containing 0.5% by weight of oil ether, and the amount of the oil agent attached to the fibers was 4.1% by weight. The stretching was performed using a hot-air stove at 180-210-248 ° C, and the total stretching ratio was 24.6 times. As for the strength of the drawn yarn, 18.2 g / d WTb showed a high value of 155 ° C.

Continued on the front page (72) Inventor Akio Omori 1621 Sazu, Kurashiki-shi, Okayama Pref. Kuraray Co., Ltd. Examiner Tadahiro Sanada (56) References Patent 2826183 (JP, B2) ⁶ , DB name) D01F 6/14

Claims (1)

(57) [Claims] 1. A polyvinylamine fiber having a viscosity-average degree of polymerization of 3,000 or more, from the spinning to immediately before dry heat drawing, of a phosphateamine compound, a phosphate compound of an amine or an amide, a sulfonate compound of an amine or an amide, and a thione compound. One or two or more surfactants selected from the compounds are applied in an amount of 0.2 to 3% by weight and an ester or mineral oil-based sizing and leveling agent in an amount of 0.5 to 5% by weight. A method for producing a hot water-resistant polyvinyl alcohol-based fiber, wherein the hot-water-water break temperature WTb satisfies the following expression, wherein the drawing is performed so that the draw ratio becomes 17 times or more. WTb ≧ 1.2A ^0.35 +125 (A ≧ 3000) where WTb is the hot water temperature (° C) under the load of 200mg / d, A
Is the viscosity average degree of polymerization of the polyvinyl alcohol polymer.