JPH1088420A - Industrial spinning of pva fiber by direct alcoholysis of pvca - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polyvinyl alcohol (PVA) fibers, improved in quality and production efficiency and useful for application of clothes, etc., by carrying out alcoholysis of polyvinyl acetate (PVCA) and then treating the resultant PVA under specific conditions. SOLUTION: An alkali is added to a solution of PVCA in MeOH (preferably at 0.0004-0.0025 molar ratio of the alkali/PVCA) and alcoholysis is carried out at 30-60 deg.C for 3-120min to control the degree of alcoholysis to 15-50mol%. The PVCA partially treated by the alcoholysis is then charged into a reactor and heated at 65 deg.C for concentrating. The resultant concentrate is subsequently filtered and degassed to provide a liquid PVA concentrate for spinning, which is fed to a spinning head for spinning under pressure. The spun fibers are continuously introduced into a coagulating alcoholytic vessel, a post alcoholytic vessel, a neutralizing vessel and an alcohol washing vessel, fed to an oil bath for oil finishing and passed through drying, hot stretching and heat setting to afford PVA fibers. The composition of the coagulating alcoholytic vessel is NaOH-H2 O and that of the post alcoholytic vessel is NaOH-MeOH. The composition of the neutralizing vessel is H2 SO4 -MeOH.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for the preparation of PVA fibers, in particular to an industrial process for the spinning of PVA fibers via direct alcoholysis of PVCA.

[0002]

2. Description of the Related Art At present, polyvinyl alcohol (PVA)
The preparation of PVA fibers from is already industrialized both domestically and abroad. However, P used for clothing
VA fiber is not as good as polyester fiber or polyamide fiber, with intermediate strength, intermediate modulus,
PVA fibers with high strength, high modulus properties can be used reinforced with cement instead of asbestos with good reinforcing effect which is widely accepted by users. In addition, due to the acid, alkali and organic solvent resistant properties of PVA fibers, they can be widely used in marine development, engineer's clothing, work pants for national defense, laying offshore lightning, and drop parachutes. And PVA
The fibers are non-toxic, non-scented, harmless and soluble in water, and are therefore used as medical materials. Widespread use.

In the industry, the traditional method of preparing PVA fibers is polyvinyl acetate (PVCA), a raw material that has been alcoholized to produce solid PVA material, which is ground with water for grinding, drying, and removing impurities. A wash is made and dissolved in water, degassed to form a concentrate, which is spun into fibers, post-processed,
This produces fibers.

[0004] The industrial technology process is as follows.

[0005] PVCA → alcoholysis → PVA → (pressurized) grinding → (three times grinding) → drying → washing → dissolution → degassing →
Spinning → post-treatment → PVA fiber

[0006]

The traditional method of preparing PVA fibers has a total of four phase transitions in all steps,
Requires numerous equipment for alcohol processing, spinning and material recovery. There are the following problems:

[0007] 1. Of all synthetic fibers, the longest technical process, the preparation of PVA fibers, is the longest technical process compared to the preparation of polyester, polyamide, acrylic and propylene fibers.

[0008] 2. In complex manufacturing processes, the production of PVA fibers, the fiber-forming polymer must undergo multiple liquid-to-solid and reversal phase transitions. It requires a lot of spinning equipment, as well as a lot of preliminary technical equipment for separation, distillate fractions, evaporation and the like. Therefore, the manufacturing process is rather complicated.

3. Due to the high energy consumption, the long process, the many preliminary equipments and the multiple transitions, the process consumes more energy than other synthetic fiber production processes.

[0010] 4. Large investment in equipment, large footprint of product and many studies must be employed.

5. PV produced from the above technical method
A-fiber has a tensile strength of at most 7 CN / dtex, thus limiting the application of such PVA fibers.

The use of cross-linked wet spinning or dry-wet spinning techniques, industrial use, can be modified into cross-sectional structures to produce high tensile strength and modulus PVA fibers, but this technical process is not an option. Are longer, energy consumption is higher, and production costs are higher.

For the reasons described above, PVA fibers produced by traditional techniques cannot compete with other synthetic fibers,
In addition, the significance of the properties unique to PVA fibers cannot be fully utilized.

It is an object of the present invention to solve the above-mentioned problems in the traditional process of PVA fiber production, to have good industrial properties of the produced fiber, short industrial technology process, reliable technology, low production cost, And PVA with high production efficiency
An industrial method by PVCA direct alcoholysis of fiber spinning is provided.

[0015]

According to the present invention, the method is as follows.

The industrial procedure for PVCA direct alcoholysis of PVA fiber spun provided by the present invention is as follows.

PVCA → alcolysis → evaporation and concentration → filtration and degassing → alcolysis spinning → alcohol washing → post-treatment → PVA fiber The above method comprises the following sequence of steps.

1. PVCA alcoholysis: Liquid PVCA
-The MeOH raw material is an alkali (an alkali ratio of 0.000
4-0.0025), partial alcoholysis is performed, the temperature of the alcohol-treated liquid is 30 to 60 ° C., the stirring speed is 20 to 120 rpm, and the alcoholic time is 30 to
120 minutes.

2. Evaporation and concentration: The partially alcohol-treated PVCA in the reactor or evaporator is heated at 65 ° C. to concentrate and to remove some of the methyl ester and methanol. Thereby, the concentration reaches 30 to 40%, and the degree of alcoholysis is controlled to 15 to 50 mol%.

3. Filtration and degassing: The degassing of the solution is taken before spinning to prevent the formation of foam filaments.

4. Alcolysis spinning: The liquid PVA spinning solution prepared from the above method is pumped to a spinning head for spinning. The spun fibers are continuously introduced into a coagulation alcoholics tank, a post-alcolysis tank, a neutralization tank and an alcohol washing tank. The alcoholysis reaction occurs simultaneously during the process of fiber formation. If desired, the degree of alcoholysis of the PVA fiber product can be controlled between 80 and 99.9 mol%. The composition of the coagulation alcoholysis bath, _NaOH-H 2 O
And the amount of NaOH is 100 to 350 g / l. The composition of the post-alcolysis tank is NaOH-MeOH.
The composition of the neutralization tank is H ₂ SO ₄ -MeOH. The composition of the alcohol washing tank is MeOH. Then, the PVA fiber is introduced into an oil finishing treatment, and the composition of the oil tank is an oil compound-MeOH.

5. Alcohol washing: Remove residual acids, alkalis similar to impurities, and recover methanol.

6. Post-treatment: Alcohol-washed PVA fibers require post-treatment. Post-treatment is performed via drying, hot stretching and heat setting to produce PVA fibers. By controlling the drying temperature, the hot stretch temperature, the hot stretch ratio, and the time for heat fixing, the PVA fiber can be produced with various grades and various properties.

According to the present invention, therefore, the industrial process for PVCA direct alcoholysis of PVA fiber spinning has the following advantages:

1. The engineering process is short. During the entire process of fiber formation, the fiber-forming polymer undergoes only one phase transition (from liquid to solid state) and thus can be pressurized, PV
Steps in traditional methods such as grinding, drying, washing with water, coagulation of the liquid fraction for dissolution and recovery of the CA alcoholysis solid product are omitted. This step is only about 50% of the conventional step.

2. The manufacturing process is simple. In the production process, the number of phase transitions of the fiber-forming polymer is reduced, no preliminary technology and equipment is required, the process is short, and the production technology is simplified.

3. This technique is diverse. In the production process, the change of PVA fiber from the PVCA concentrate is completed by a chemical reaction. By controlling the chemical reaction process, PVA fibers having various degrees of alcoholysis can be obtained. From products with different degrees of alcoholysis,
By changing the industrial technology and using the same manufacturing equipment, multi-grade fiber with various properties such as high modulus fiber, water soluble fiber, paper manufacturing fiber, long fine fiber, etc. to meet the market demand May be produced, thereby promoting the competitiveness of the product.

4. Low production cost. The simplicity of industrial technology, shortened industrial technology processes, reduced capital investment and plant footprint, reduced energy consumption, did not require research, also promoted the nature and quality of textile products All of these result in a significant 30% reduction in production costs of this technology compared to traditional traditional technologies.

[0029]

The present invention provides the following examples.

Example 1 Using the technique of the present invention for spinning PVA fibers from PVCA direct alcoholysis.

The technical technique is as follows.

(1) PVCA alcoholysis: PVCA- to which alkali (alkali ratio 0.0009) is added
MeOH solution is injected into the reactor volume of 4M ^3, agitation speed 60 rpm, temperature of alcoholysis liquid 50 ° C.,
The alcoholysis time was 60 minutes and partial alcoholysis was performed.

(2) Evaporation and concentration: The partially alcohol-treated PVCA solution was stirred and heated at 65 ° C. to evaporate the alcohol to concentrate and remove some of the methyl ester and methanol. After concentration, the solids content in the liquid is 35% at a stirring speed of 20 rpm.

(3) Filtration and degassing: The solution is degassed before spinning in order to prevent the formation of foamed filaments.

(4) Alcolysis spinning: The liquid PVA spinning concentrate prepared from the above-mentioned process is fed to a spinning head (1800).
The spinning is performed by pressure feeding to a 0-hole spinning discharge plate (hole diameter: 0.1 mm).

(5) Alcohol washing: The spun fibers are continuously introduced into a coagulation alcoholysis tank, a post-alcolysis tank, a neutralization tank, an alcohol washing tank and an oil tank. The composition of the coagulation alcoholysis tank is NaOH-H ₂ O, NaOH
The amount is 200 g / l. The composition of the post-alcolysis tank is
NaOH-MeOH, and the amount of NaOH is 5 g / l. The composition of the neutralization tank is H ₂ SO ₄ -MeOH,
_The amount of ₂ SO ₄ is 48 g / l. The composition of the alcohol cleaning bath liquid is MeOH. Then, the spun fibers are introduced into an oil tank for oil finishing and the composition of the oil tank liquid is an oil compound-MeOH.

(6) Post-treatment: The post-treatment method is basically the same as the traditional method, that is, the steps of drying, hot stretching and heat fixing, and produce PVA fibers.

Properties of PVA fiber prepared according to this example: tensile strength 8CN / dt, elongation at break 15%
Hereinafter, the modulus is 180 CN / dt, and the cross-sectional fiber is an annular shape.

Example 2: Using the technique of the present invention for spinning PVA fibers by PVCA direct alcoholysis.

The technical method is as follows.

(1) PVCA alcoholysis: PVCA to which alkali (alkali ratio 0.0008) is added
MeOH solution is in part alcoholysis is performed injected into reactor volume of 4M ^3, the temperature of the alcoholysis liquid 6
0 ° C., stirring speed 40 rpm, alcoholysis time 120
Minutes.

(2) Evaporation and concentration: The partially alcohol-treated PVCA solution is stirred and heated to evaporate the alcohol to concentrate at 65 ° C., and the stirring speed is 120 rpm.
pm.

(3) Filtration and degassing: The solution is degassed before spinning in order to prevent the formation of foamed fibers.

(4) Alcolysis spinning: The liquid PVA spinning concentrate prepared from the above-mentioned step was fed to a spinning head (9000).
The spinning is performed by pressure feeding to a spinning discharge plate having a hole diameter of 0.16 mm.

(5) Alcohol washing: The spun fibers are continuously introduced into a coagulation alcoholysis tank, a post-alcolysis tank, a neutralization tank, an alcohol washing tank and an oil tank.

The composition of the coagulation alcoholysis tank is NaOH-
H ₂ O and the amount of NaOH is 200 g / l. The composition of the post-alcolysis tank was NaOH-MeOH,
The amount of aOH is 5 g / l. The composition of the neutralization tank is H ₂ SO
₄ is -MeOH, H ₂ SO ₄ amount is 48 g / l. The composition of the alcohol cleaning bath liquid is MeOH. Thereafter, the spun fibers are introduced into an oil tank for oil finishing, wherein the composition of the oil tank liquid is an oil compound-MeOH.

(6) Post-treatment: The post-treatment method is basically the same as the traditional post-treatment method, that is, the steps of drying, hot stretching and heat setting, and produce PVA fibers.

Properties of PVA fiber prepared according to this example: tensile strength is 12.8 CN / dt, elongation at break is 8% or less, modulus is 356 CN / dt, and cross-sectional fiber is annular.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Ye Gwangdu, China, Gansuhun, Ranjushi, Sigtchu, Hokwangan Sinweil, 103 Hao (72) Inventor Li Shaochun, China, Ganshuen, Ranjyu Si, Sigchu, Ho Kunan Singh Weil, 103 Hao (72) Inventor Tien Shupin, China, Gansh ン n, Ranjushi, Sigtu, Ho Ku Nan Singh Wei, 103 Hao, 72 Inventor Zaan Ji Lou, China Gangshun, Ranjushi, Sigtchu, Hokwangan Shinweil, 103 Haoゥ Kwang Nan Shin Weil, 103 Hao (72) Inventor Juan Bao Shun, China Si, Sigchu, Ho Kuo Nan Singh Way, 103 Hao (72) Inventor Gao Dong Hong, China, Gan Soo Shun, Ranjushi, Shig Chu, Ho Kuo Nan Singh Way, 103 Hao (72) Inventor Wang Ping China, Gangshun, Langush, Sigtchu, Ho Kwang Nan Shin Weil, 103 Hao

Claims (3)

[Claims] 1. PVA by direct alcoholysis having a process sequence of polyvinyl acetate (PVCA) → alcolysis → evaporation and concentration → filtration and degassing → alcolysis spinning → alcohol washing → post treatment → polyvinyl alcohol (PVA) fiber
An industrial process for spinning A-fiber, wherein the technical techniques are as follows: (1) PVCA-alcolysis: PVCA-MeOH solution is alkali (alkali; PV
(0.0004-0.0025 mole ratio of CA) is added. (2) Evaporation and concentration: The partially alcohol-treated PVCA is charged to a reactor with stirring and heated at 65 ° C. for concentration. 3) Filtration and degassing: degassing is performed before spinning. (4) Alcolysis spinning: liquid P prepared in the above process
VA spinning concentrate is pumped to the spinning spinning head, spinning fibers coagulation alcoholysis tank, rear alcoholysis tank continuously introduced into the neutralization tank and an alcohol cleaning bath, the composition of the coagulation alcoholysis tank, NaOH-H ₂ O The composition of the post-alcolysis tank is NaOH-MeOH; the composition of the neutralization tank is H ₂ SO ₄ -MeOH;
The composition of the alcohol wash tank is MeOH; then the fiber is sent to oil finishing oil tank, (5) Post-treatment: Post-treatment method is through drying, hot stretching, heat setting, and thereby PVA fiber To produce. 2. In the step (1), the temperature of the liquid subjected to the alcohol treatment is 30 to 60 ° C., the alcoholysis time is 3 to 120 minutes, and the alcoholysis degree is 1
The PV according to claim 1, which is controlled in a range of 5 to 50 mol%.
Industrial method of A fiber spinning. 3. The composition of the coagulation bath liquid is NaOH-H ₂
2. The industrial method for spinning PVA fibers according to claim 1, wherein the amount of NaOH is 100 to 350 g / l.