JPS5838532B2 - Method for manufacturing acrylic hollow fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing acrylic hollow fibers with excellent industrial productivity and having uniform cavities by a wet spinning method using an acrylonitrile polymer.

Conventionally, when producing hollow fibers using a wet spinning method, a blowing agent is dispersed in a spinning stock solution and the foaming agent is foamed in a swollen gel-like yarn that is spun and solidified, or a surfactant is used in combination with the above spinning stock solution. There are known methods for improving the dispersibility of blowing agents.

However, in the method of dispersing the blowing agent in the spinning dope, the dispersion of the blowing agent is generally uneven, and when the spinning dope is transferred, the blowing agent aggregates over time, and this coagulation occurs at the top of the transfer pipe. During fiberization, the spinnability of the fibers decreases, and the resulting fiber bundles are mostly made up of fibers without cavities, making them unsatisfactory as hollow fibers.

In addition, in the method of using a surfactant in the spinning dope mentioned above,
The dispersibility of the blowing agent is improved, and agglomeration of the blowing agent in the spinning dope is prevented, and the proportion of hollow fibers in the obtained fiber bundle is improved. Extensive elution into baths, washing baths and stretching baths occurs.

Elution of the surfactant into the coagulation bath leads to difficulty in recovering the coagulation bath solvent, and elution into the washing bath and stretching bath increases the C0D (chemical oxygen demand) in the factory wastewater due to its outflow into the wastewater. ), all of which caused major problems in industrial production.

As a result of intensive research to improve the drawbacks of conventional methods as described above, the present inventors found that at least one of the ester groups in the ester of a polymerizable unsaturated carboxylic acid has a general formula (where R is a carbon 1 selected from the group consisting of alkoxy groups, acyloxy groups, and alkylphenoxy groups of number 6 or more
(hereinafter referred to as the compound of the present invention)
A spinning dope made of an acronitrile polymer or mixed polymer containing has excellent surface activity and
The present invention was achieved by discovering the novel fact that there is no concern about elution into the coagulation bath, washing bath, and drawing bath that occurs when a surfactant is added to the spinning dope.

The objects of the present invention are (1) uniform dispersion of the blowing agent and excellent stability in stock solution transfer and spinning stability;

(2) Excellent industrial productivity, with no elution of the surfactant into the coagulation bath, washing bath, or drawing bath, making it easy to recover the solvent, and eliminating the risk of increasing COD due to leakage into factory wastewater. The present invention provides a method for producing acrylic hollow fibers having uniform cavities.

That is, the present invention uses a spinning stock solution made of an acrylonitrile polymer containing at least 60% acrylonitrile as a sheath component when simultaneously extruding two types of spinning stock solutions from a common spinneret so as to form a sheath-core shape. As the core component, an acrylonitrile polymer or mixed polymer containing 0.1% or more of the compound of this component and a compound that is poorly soluble or insoluble in water and has a boiling point of 95°C or less are used as a blowing agent (hereinafter referred to as the present invention). 1 as a blowing agent for the above acrylonitrile polymer or mixed polymer.
Using a spinning dope containing ~40%, the discharge ratio during spinning is set to core component/sheath component = 20/80 to 80/20, and the purpose is distantly related by wet spinning into an aqueous coagulation bath. be able to.

The compounds of the invention are esters of polymerizable unsaturated carboxylic acids.

Examples of such esters of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid.

In the ester, at least one of the ester groups has the general formula (where R is 1 selected from the group consisting of an alkoxy group having 6 or more carbon atoms, an acyloxy group, and an alkylphenoxy group).
, m is O or a small positive value, and n is a value of 5 or more).

The number of carbon atoms in the above R must be 6 or more, and if the number of carbon atoms is less than 6, the surface active ability necessary for the present invention is insufficient.

Specific examples of R include alkoxy groups such as a heptyloxy group, an octyloxy group, a nonyloxy group, a lauryloxy group, a zetyloxy group, and a stearyloxy group, an ophthyroyl group, a lauroyl group, a capryloyl group, a myristyroyl group, a cetyloxy group, and a stearoyl group. and alkylphenoxy groups such as nonylphenoxy, laurylphenoxy, and cetylphenoxy groups.

It is preferable that the number of moles of ethylene oxide units added is 5 or more, so that the surfactant ability necessary for the present invention is exhibited, and less than 5 is insufficient.

In some cases, ethylene oxide containing a small amount of propylene oxide can be used to lower the melting point and control the balance between hydrophilicity and hydrophobicity.

The acrylonitrile polymer or mixed polymer containing the compound of the present invention is a binary copolymer of the compound of the present invention and acrylonitrile, or a ternary, quaternary or higher copolymer further containing a third monomer, etc. Alternatively, a copolymer consisting of a combination of the above monomers and ordinary acryloni)
It is a mixed copolymer that is a combination of an IJ type copolymer,
In any case, it is necessary that the compound of the present invention is contained in an amount of o, i% or more, preferably 1% or more; if it is less than 0.1%, the surfactant ability necessary for the present invention is insufficient. .

If the amount exceeds 35% by weight, the physical properties of the resulting fibers deteriorate, particularly the color fastness.

The acrylonitrile polymer containing the compound of the present invention needs to contain 30% or more of acrylonitrile.

If the acrylonitrile content is less than 30%, the degree of polymerization of the polymer will be low, which is undesirable from the viewpoint of elution into the coagulation bath.

Examples of the third monomer include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylamide, methacrylamide, vinyl acetate, styrene, vinyl chloride, vinylidene chloride, allylsulfonic acid, methallylsulfonic acid, and styrenesulfonic acid. and salts of the above-mentioned sulfonic acids, and other conventionally known compounds.

The ordinary acrylonitrile copolymer used herein means an acrylonitrile homopolymer or an acrylonitrile copolymer containing 60% or more of acrylonitrile.

Further, the method for producing the polymer of the present invention may be any method such as solution polymerization, aqueous slurry polymerization, etc., as required, and is not subject to any restrictions regarding the polymerization method.

Any solvent can be used as long as it can dissolve the polymer.

Examples include inorganic acids such as nitric acid and sulfuric acid, inorganic salts such as zinc chloride and rhodan soda, organic compounds such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and ethylene carbonate, or mixtures of one or more of these, but in particular nitric acid. The effect is remarkable when using .

The concentration of the polymer or mixed polymer of the present invention in the spinning stock solution is preferably 7 to 30%, and the viscosity used is 200 to 1000 poise, but in order to improve the generation of hollows, it is 50 to 85%.
0 poise is preferred.

As the blowing agent added to the spinning dope, an inorganic or organic volatile substance that is sparingly soluble or insoluble in water at the temperature of the coagulation bath and has a boiling point of 95° C. or lower is used.

For example, air, nitrogen, carbon dioxide 1, propane, butane,
Pentane, hexane, heptane, benzene, cyclohexane, cyclohexadiene, cyclopencune, dimethylbutane, dimethylfuran, ethyl ether, carbon disulfide, carbon tetrachloride, butyl chloride, propionyl chloride, propyl chloride, allyl chloride, inamyl chloride, vinylidene chloride, etc. can be given.

The effect can be observed at any time when the foaming agent of the present invention is introduced into the spinning stock solution, at least before the spinning stock solution is combined with the spinning stock solution of the sheath component.

The amount of the blowing agent added is 1 to 40%, preferably 2 to 30%, based on the total polymer contained in the core component spinning dope.

If the amount of the blowing agent added is less than 1%, the degree of hollowness of the obtained fibers will not be sufficient, and if it exceeds 40%, the spinnability will deteriorate, which is not preferable.

The size of the blowing agent particles dispersed in the spinning dope is 1 in diameter.
The size of the particles is preferably 0 μ or less, especially about 5 μ, and if the particles are too large, the spinnability may deteriorate or breakage may occur during stretching, which is undesirable.

Further, the concentration of the acrylonitrile polymer in the spinning stock solution of the sheath component is desirably 7 to 30%, and the viscosity is suitably 20 to 1000 poise.

The two types of spinning stock solutions prepared as described above are passed through a conventional sheath-core type composite spinneret, and are made of an acrylonitrile polymer or a mixed polymer containing the compound of the present invention and the blowing agent of the present invention. The spinning dope is extruded into an aqueous coagulation bath to form a coagulated strip with a core component and a discharge ratio of core component/sheath component of 20/80 to 80/20.

Here, the discharge ratio of the core component/sheath component is indicated by the discharge amount ratio per hour of the combined amount of both types contained in the spinning dope, and the core component accounts for less than 20% of the discharge ratio. In this case, the degree of hollowness of the obtained fiber is insufficient, 80%
If the temperature exceeds 100%, a decrease in physical properties will be observed.

The aqueous coagulation bath in the present invention contains 30% or more of water,
Preferably, those containing 40% or more are used from the viewpoint of incompatibility with the blowing agent.

Further, the temperature of the aqueous coagulation bath is 50°C or lower, preferably 40°C or lower; if the temperature is higher than 50°C, it is difficult to obtain good hollow fibers.

The filament coagulated in the coagulation bath described above is then washed with water and drawn according to a conventional method. However, the hollowing of the fiber of the present invention is carried out during coagulation, washing, stretching, etc. while the filament is in a swollen gel state. The strip is heated to a temperature higher than the boiling point of the foaming agent and the foaming agent evaporates to form cavities.

The fibers are then dried, oil treated and heat relaxed.

The fiber thus obtained is a hollow fiber having fine elongated cavities uniformly throughout the fiber.

In addition, in the above-mentioned fiberization process of the present invention, the elution into the coagulation bath, water washing bath, and drawing bath is such that no turbidity is observed in each treatment bath and the amount of elution is smaller than when a surfactant is added to the spinning dope. It had excellent industrial productivity.

The present invention will be explained below with reference to Examples.

The percentages in the examples are expressed by weight.

Further, the amount of carbon eluted into the coagulation bath was measured by the following method.

That is, the coagulation bath solution after spinning for a predetermined period of time is collected, concentrated under reduced pressure, and further dried.

The dried product is decomposed using a decomposition solution consisting of a chromium-phosphoric acid mixture, and the generated carbon dioxide gas is absorbed into an alkaline solution and quantified.

The quantitative value is expressed as weight % based on the amount of acrylonitrile copolymer drawn and spun.

Example 1 As a sheath component stock solution, 15% acrylonitrile copolymer consisting of acrylonitrile (hereinafter AN)/methyl methacrylate (hereinafter MAM)/methacrylsulfonate sodium (hereinafter MAS) = 92.77770.3 was mixed with 67% nitric acid aqueous solution 85%. % stock solution (S stock solution) was prepared.

The above stock solution VC4 as a core component stock solution 2 Hexane as a foaming agent
A mixture of 0% (A stock solution) and a mixture of the same amount of hexane and 2.8% of polyoxyethylene (additional moles of oxyethylene 40) stearylniteri as a surfactant (S stock solution) and the same amount of A mixture of hexane and AN in an amount of 2.8% (stock solution C) was prepared into a uniform dispersion liquid and a stock solution.

The above stock solutions were combined with S-A, S-B, and S-C using a sheath-core type composite spinneret with a pore diameter of 0.08 mm and a number of holes of 200 to give a core component/sheath component ratio of 60/40. With the discharge ratio,
extruded into a coagulation bath consisting of a 30% nitric acid aqueous solution at 0°C,
After thoroughly washing with water in a water washing bath, hexane was evaporated in a stretching bath made of boiling water, and the film was stretched 7 times.

The experiment was continued over a long period of time and the following measurements were made.

(1) Dispersion state A, B of blowing agent particles in the core component spinning dope
Figure 1 shows the dispersion state of hexane particles observed with an optical microscope for each stock solution C, and it is clear that the stock solution C of the present invention is distributed on the smaller particle size side, and the stock solution B to which a surfactant is added is
It shows the same dispersion as .

A blowing agent dispersed with a particle size of 10 μm or less has extremely good stability and coarsening due to particle growth can be ignored.

(2) Spinning stability and state of elution into the coagulation bath, washing bath, and drawing bath In spinning using the S-A stock solution, agglomeration of the blowing agent was observed in the upper part of the &-[A stock solution piping 22 hours after the start of spinning. A pulsating flow occurred in the raw solution exiting the spinneret, making hot drawing impossible, and then, at 33 hours, it became difficult to spin the yarn.

In spinning using the S-S stock solution, turbidity in the coagulation bath and bubbling in the washing bath and drawing bath were observed from the start of spinning at 30 o'clock, and at about 46 o'clock the above-mentioned turbidity and turbidity were extremely noticeable. It became.

In spinning using the SC stock solution, no change was observed even 96 hours after the start of spinning, and stable spinning was possible.

By the way, the spinning start time 30 in the above spinning using each stock solution
The results of measuring the amount of carbon eluted into the coagulation bath at the time were as follows: S-A stock solution 0.002%, S-S stock solution 0.01%,
The S-C stock solution was 0.002%, and it was confirmed that the S-S stock solution was significantly eluted into the coagulation bath, washing bath, stretching bath, etc.

(3) Cross section of hollow fiber The drawn yarn obtained in the above experiment 12 hours after the start of spinning was dried and further subjected to thermal relaxation treatment in saturated steam at 120°C. The cross section of the obtained fiber was observed using a microscope. The results are shown in Figure 2.

It can be seen from FIG. 2 that the fibers obtained from the S-A stock solution have insufficient hollowness, whereas the fibers obtained from the S-C stock solution have elongated cavities uniformly throughout the fiber.

As is clear from the above examples, according to the present invention, the blowing agent is uniformly dispersed and has excellent operability such as transferring the stock solution over a long period of time, and there is no elution of surfactants etc. into the coagulation bath or washing bath. It can be seen that acrylic hollow fibers having uniform cavities with excellent productivity can be obtained.

Example 2 AN/acrylamide (hereinafter referred to as AA)/MA894.51
An acrylonitrile copolymer consisting of 510.5 and 67
% nitric acid aqueous solution, 6% carbon tetrachloride as a blowing agent, and the amount shown in Table 1 of the acrylonitrile polymer consisting of the combination shown in Table 1 were mixed to form a uniform dispersion with a core having a polymer concentration of 15%. A spinning dope for components was obtained.

These stock solutions and the spinning stock solution for the sheath component of Example 1 (S stock solution)
Table 1 shows the results of examining the long-term spinning time possible in the same spinning as in Example 1 by combining the following.

As is clear from Table 1, the compounds of the present invention significantly improve the dispersibility of carbon tetrachloride as a blowing agent, improve spinning stability, and provide excellent industrial productivity.

Example 3 AN/AA/MAN/MAS-92 as sheath component stock solution,
A spinning stock solution (T stock solution) was prepared by dissolving 18% of an acrylonitrile copolymer consisting of 4/4/310.6 in 82% of a 65% nitric acid aqueous solution.

As the core component stock solution, AN/ CH2=C-COOCH3 CH2C00 (CH2CH20jikaru C9H19MAM/
MAS=82.5/1215/'0.5 18% acrylonitrile polymer and 65% nitric acid aqueous solution 82%
A spinning stock solution (stock solution D) was prepared by mixing 12% of cyclopeatane as a foaming agent into the solution.

The discharge ratio of the above two kinds of stock solutions was changed as shown in Table 2, and the pore size was 0.
The cyclopentane was extruded through a sheath-core type composite spinneret with a diameter of 0.7 mm and 500 holes at 0°C into a coagulation bath consisting of a 35% nitric acid aqueous solution and then washed with water. Stretching was performed.

Next, the fibers were dried and thermally relaxed in saturated steam at 110° C., and the cross section of the resulting fibers was observed under a microscope to determine the degree of hollowness of the fibers. Table 2 shows the results.

Table 2 shows the results of measuring the strength of the fibers.

As is clear from Table 2, the fibers of the present invention have uniform cavities and are also excellent in physical properties.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram showing the dispersion state of blowing agent particles observed with an optical microscope for each stock solution shown in Example 1, and FIG. 2 is a cross section ( (reproduction).

Claims (1)

[Scope of Claims] An acrylonitrile polymer containing at least 60% acrylonitrile as a sheath component, in which 12 types of spinning dope are simultaneously extruded from a common spinneret to form a sheath-core shape. The core component is a polymerizable unsaturated carboxylic acid ester, and at least one of the ester groups is of the general formula (where R is an alkoxy group having 6 or more carbon atoms, an acyloxy group, an alkylphenonoxy group). an acrylonitrile polymer containing 0.1% or more of a compound having a group selected from the group consisting of one member selected from the group consisting of m is O or a small positive value, and n is a value of 5 or more. or a mixed polymer, which is sparingly soluble or insoluble in water and contains 9
1 to 4 for the above acrylonitrile polymer or mixed polymer using a compound having a boiling point of 5°C or less as a blowing agent.
An acrylic hollow fiber characterized by wet spinning into an aqueous coagulation bath using a spinning dope containing 0%, with a discharge ratio during spinning of core component/sheath component -20/80 to 80/20. manufacturing method.