JPS5953364B2 - Manufacturing method of hollow acrylic fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing hollow acrylic fibers by wet spinning.

Acrylic fibers, which have a large number of pores inside the fibers, are expected to be lightweight and provide a sublime and soft feel.

Conventionally, as a technique for obtaining hollow acrylic fibers, a method is known in which a specific blowing agent is added to a stock solution of an acrylonitrile polymer and foamed in a heat treatment in a post-process (Japanese Patent Application Laid-open No. 149922/1982). Public bulletin).

However, with this method, the pores caused by foaming tend to disappear during the densification process, and even if they remain, there are only 1 to 3 relatively large pores per fiber cross section at most, so it is unlikely that a fundamental change in the fiber texture will occur. Monakatsu 7.

Also, Japanese Patent Publication No. 54-43618 and Japanese Patent Publication No. 54-4
No. 3619 discloses a technique in which liquid paraffin and chlorinated paraffin are added to an acrylonitrile polymer stock solution, and after spinning, the added substances are removed using a solvent.

1 It is true that this method produces countless micropores and can reduce the weight of the fiber.

However, since the pores formed are relatively small, light is diffusely reflected, and the dyed product has a dull, devitrified color, making it impossible to maintain the vivid color development that is the original characteristic of acrylic fibers.

Furthermore, from an industrial standpoint, it is necessary to remove additives from the final raw cotton or yarn fabric using an organic solvent, which is economically fatal when considering the complexity of post-processes and the recovery of additives and extraction solvents. It is clear that it has some serious flaws.

An object of the present invention is to provide a novel method for producing hollow acrylic fibers that does not have the above-mentioned drawbacks.

That is, the present invention provides a method for wet spinning of acrylic fibers.
9.5 to 85% by weight of acrylonitrile polymer and 0.9% by weight of acrylonitrile polymer;
The present invention relates to a method for producing hollow acrylic fibers, which comprises spinning a mixed solution of polyalkylene oxide having a number average molecular weight of 100,000 or more and having a number average molecular weight of 5 to 15% by weight into a coagulation bath.

According to the method of the present invention, substantially all of the polyalkylene oxide added and mixed is eluted through the coagulation, water washing, and stretching processes of the fibers, and surprisingly, by using polyalkylene oxide having a molecular weight of 100,000 or more, the polyalkylene oxide is eluted. The generated pores remain without being burned out even after drying and densification, and the pore diameter after densification is 0.5 to 3μ.
A fiber having a large number of hollow parts can be obtained.

Furthermore, the fibers obtained by the method of the present invention are light and soft due to the large number of pores, and the fiber surface is moderately roughened due to the elution of polyalkylene oxide, so that a soft feel can be obtained with a dry touch.

Furthermore, since the pores are suitably large, ranging from 0.5 to 3 microns, the fibers do not lose their vivid color development, which gives them a devitrified tone.

What is also noteworthy is that since non-toxic water-soluble polyalkylene oxide is used as the mixed spinning additive, it can be eluted into the coagulant and water during the fiber manufacturing process without using any special extraction solvent. This is an industrially extremely advantageous production method without the problem of wastewater toxicity.

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

In the present invention, it is essential that the substance to be mixed with the acrylonitrile polymer is a polyalkylene oxide and that the number average molecular weight of the substance is 100,000 or more.

It is known to spin an acrylonitrile-based polymer by adding a polymer solvent and, in some cases, a water-soluble polymer substance, such as cellulose acetate, methyl cellulose, hydroxyethyl cellulose, polyvinylpyrrolidone, polyacrylamide, polyvinyl acetate, Polyvinyl alcohol, polyethylene glycol, polyamide, specific protein AS resins, etc. are known.

The aim of this technology is to impart antistatic properties, dyeability, hygroscopic properties, etc., and the main idea is to actively introduce them into fibers.

Even if there was an idea to remove polyethylene glycol from the fibers, the fact is that polyethylene glycol is a substance that is highly soluble and easily eluted; Polyethylene glycol is called polyethylene glycol, and polymers with an average molecular weight of about 100,000 or more have different properties and are classified as polyethylene.

It is clear from the present invention that the pores targeted by the present invention are not generated at all if oxides (also called oxides) are used.

Here, the remarkable inventive step of the present invention can be emphasized.

If the number average molecular weight of the polyalkylene oxide is less than 100,000, it will only be eluted in the order of fine molecules during the fiber manufacturing process and no pores will be generated.

Although the reason for this is not clear, the present inventors assume the following.

Polyalkylene oxide is soluble in the selected acrylonitrile polymer solvent, but when a mixed stock solution of acrylonitrile polymer and polyalkylene oxide was closely observed under an optical microscope, it was found that the number average molecular weight was 10.
In the case of polyalkylene oxide of 20,000 or more, it is observed that the polyalkylene oxide is dispersed and dissolved in the stock solution of the acrylonitrile polymer in the form of phase-separated spheres with a diameter of 1 to 15 μm.

This state basically remains unchanged even if strong stirring and mixing are performed.

These small islands are eluted as blocks in the coagulation bath, washing bath, drawing bath, etc. during the fiber formation process, resulting in 0.5 to 3
It is thought that μ vacancies are generated.

On the other hand, when polyalkylene glycol with a small molecular weight is added, does it show a uniform phase under an optical microscope? It is thought that when spun into fibers, pores are not generated, or even if they are formed, they are crushed by the densification process, or even if some remain, they do not become micropores in the order of angstroms.

In any case, it is not possible to obtain a fiber texture with a light and soft feel.

The amount of polyalkylene oxide mixed and added is preferably 0.5 to 15% based on the total solid weight.

If the amount added is less than 0.5%, the number of pores will not be sufficient, while if it exceeds 15%, the number of pores will increase significantly, but many weak points will occur in the fiber, resulting in frequent fiber breakage during the manufacturing process. Not only this, but also the mechanical properties of the resulting fibers are not practical and are therefore undesirable.

As the polyalkylene oxide of the present invention, polyethylene oxide, polypropylene oxide, and polyoxyethylene polyoxypropylene block polymer having a number average molecular weight of 100,000 or more can be used.

They may be added alone or in combination of two or more.

Furthermore, there are no restrictions on the possibility of further adding other inorganic or organic modifiers, such as titanium oxide, if necessary.

The acrylonitrile polymer used in the present invention contains 80% by weight or more of acrylonitrile and can be produced by known suspension, emulsification, or solution polymerization methods.

The polymer may be a copolymer of less than 20% of one or more copolymerizable monomers in addition to polyacrylonitrile, and such units include methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, Examples include, but are not limited to, vinylidene chloride, styrene, dimethylaminoethyl methacrylate, vinylpyridine, acrylamide, sodium methallylsulfonate, sodium allylsulfonate, and sodium styrenesulfonate.

Any of the following methods may be used to mix the acrylonitrile polymer and polyalkylene oxide.

1. Mix and dissolve polymer powders in a common solvent.

2. Dissolve one of the polymers in a solution in which the other is dissolved in advance.

3. Mix the solutions separately dissolved in the same solvent.

The solvent used for spinning needs to be a common solvent for the acrylonitrile polymer and polyalkylene oxide.

As such a solvent, a concentrated aqueous solution of nitric acid, a concentrated zinc chloride solution, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide can be used, but the present invention is not limited thereto as long as it is a common solvent.

Further, as a spinning method for the mixed stock solution, wet spinning is required.

In the dry spinning method, in which the solvent is removed using hot air, a dense skin layer is formed on the fiber surface, so it is extremely difficult to elute high molecular weight substances such as polyalkylene oxide in the subsequent process. No voids are generated.

After the mixed stock solution is spun into a coagulation bath depending on the solvent used,
The fibers are processed by known methods such as water washing, stretching, drying, heat setting, etc. necessary for fiber formation.

A feature of the present invention is that the pores generated do not disappear and are retained even after undergoing densification treatment.

Although polyalkylene oxide is eluted during any of the coagulation, water washing, and hot water stretching processes, it seems that the eluting process is mainly large in the coagulation bath.

Although it is possible to control the elution amount to some extent by spinning conditions such as the concentration and viscosity of the stock solution, coagulation bath composition, temperature, and draft applied to the gel filaments in the bath, this is not particularly important and is subject to densification processing. The amount of polyalkylene oxide remaining in the previously drawn raw silk is zero or extremely small, and substantially all of the mixed polyethylene oxide is eluted during the intermediate process, creating a large number of pores.

The manufacturing method of the present invention may include a spinning method for obtaining a single-component acrylic fiber, as well as a multi-component composite spinning method for obtaining a bimetallic or sheath-core structure.

In this case, the polyalkylene oxide may be mixed with the acrylonitrile polymer stock solution of one or all components, and can be selected depending on the purpose.

The hollow acrylic fibers obtained by the method of the present invention may be used alone or blended, twisted, knitted, or woven with other fiber materials such as polyester, nylon, wood, cotton, wool, silk, hemp, and cellulose yarn regenerated fibers. It can be processed into fabric, but
All of them exhibit the characteristics of hollow fibers, creating a unique texture that is light, soft, and dry to the touch.

1 Furthermore, the color development is as vivid as normal acrylic fibers, and there is no inferiority.

Example 1 Acrylonitrile/vinyl acetate/sodium allylsulfonate (90/9.810.2) wt% by suspension polymerization
) was produced.

18 parts of the polymer and 1 part of polyethylene oxide having an average molecular weight of 500,000 were mixed and dissolved in 81 parts of 70% nitric acid.

A helical ribbon type dissolving machine was used for dissolving.

When observing the state of the stock solution with an optical microscope, it was observed that polyethylene oxide was dispersed and dissolved in the form of phase-separated islands of 1 to 15 μ in size in a sea of uniformly dissolved acrylonitrile polymer. Ta.

This stock solution was cooled to -5°C and pumped with a gear pump to create a hole with a diameter of 0.
．． 08mm, through a spindle with 50,000 holes, 4
It was extruded into a 32% concentration nitric acid coagulation bath maintained at .degree.

The draft in the bath was set at 0.62. A fiber having a fineness of 2 denier was obtained by washing with water, stretching with hot water (9 times), drying, setting with heat, and oiling according to a conventional method.

An analysis of the amount of polyethylene oxide remaining in the fibers for each process revealed that it was 1.1% owf for coagulated yarn and 0 for washed yarn.
, 3% owf, and 0.05% owf in the final fiber, and substantially all of the added polyethylene oxide was eluted during the manufacturing process.

When the obtained fiber surface (shown in Figure 1) and side surface (shown in Figure 2) were observed with an optical microscope, the fiber axis direction was 0.5 to 2.
It was confirmed that there were many elongated pores with a diameter of μ.

The apparent specific gravity was found to be 0.90 from the fiber diameter measurement, and it was found that the weight was reduced by about 26% from the true specific gravity of 1.17.

The fiber was cut into a length of 51 mm and spun into a No. 52 single yarn.
After dyeing, it was knitted into a smooth fabric.

Comparing the texture of silk fabric with that of ordinary acrylic fibers without hollow parts, the fabric made of the fibers of the present invention is extremely soft and dry to the touch, has a unique texture, and has no loss. There was no transparency and the color development was comparable to that of ordinary acrylic fibers.

Example 2 Acrylonitrile/methyl acrylate/sodium methallylsulfonate (92,2/7.210.6 weight 6%
) and polyethylene oxide having an average molecular weight of 500,000, hollow fibers were produced according to the method of Example 1 by changing the mixing ratio.

As shown in Table 1, the results show that the fibers obtained by adding polyethylene oxide within the range of the present invention have good hollowness and good fiber properties, while the fibers with the added amount less than the range of the present invention have a hollow state. On the other hand, fibers with too much added content were sufficient to reduce weight, but the fibers were often cut during the manufacturing process and the fiber properties were unsatisfactory. .

Example 3 Acrylonitrile copolymer 12 consisting of acrylonitrile/methyl acrylate/sodium methallyl sulfonate (92,2/7.210.6% by weight) and polyethylene oxide with different molecular weights (low molecular weight ones are polyethylene glycol and 0.4 part of the above solution was mixed and dissolved in 87.6 parts of a mixed solution of 40% zinc chloride and 12% sodium chloride kept at 55°C.

This stock solution was passed through a spinneret with a pore size of 0.06 mm for 5 minutes.
The fibers were spun into a zinc chloride coagulation bath with a concentration of 18% kept at .degree. C., and subjected to water washing, hot water stretching, drying, and heat setting treatment by conventional methods to obtain fibers with a fineness of 1.5 denier.

The properties of the obtained fibers are shown in Table 2.

No hollow parts were observed in the fibers obtained by adding polyethylene oxide having a molecular weight outside the range of the essential conditions according to the present invention, and the apparent specific gravity was also the same as that of ordinary acrylic fibers.

Example 4 18 parts of an acrylonitrile polymer consisting of acrylonitrile/methyl acrylate/acrylamide (89/5/6% by weight) was dissolved in 82 parts of dimethyl sulfoxide kept at 60°C.

To this stock solution, 1.5 parts of various polymeric substances shown in Table 3 were added and stirred to prepare a mixed stock solution.

Various stock solutions were spun through a spinneret with a diameter of 0.1 mm into a 52% dimethyl sulfide coagulation bath kept at 40°C, and then
After passing through a 30% dimethyl sulfide bath kept at
Water washing, hot water stretching, drying, and heat setting were performed.

The results are shown in Table 3, and no pores were observed in the fibers obtained by adding substances other than the method of the present invention.

[Brief explanation of the drawing]

The drawing shows a hollow acrylic fiber obtained by one embodiment of the present invention observed under an optical microscope (magnification: 700x)
FIG. 1 is a cross-sectional view of the fiber, and FIG. 2 is a side view. In the figure, the blacked out areas indicate holes.

Claims (1)

[Claims] 1. In wet spinning of acrylic fiber, 99.5 to 85
A method for producing hollow acrylic fibers, which comprises spinning a mixed solution of an acrylonitrile polymer in an amount of 0.5 to 15% by weight and a polyalkylene oxide having a number average molecular weight of 100,000 or more into a coagulation bath. 2. The method for producing hollow acrylic fibers according to claim 1, wherein the polyalkylene oxide is polyethylene oxide, polypropylene oxide, or polyoxyethylene polyoxypropylene block polymer. 3. Claim 1, wherein the acrylonitrile-based polymer is a polymer consisting of 80% by weight or more of acrylonitrile.
Method for manufacturing hollow acrylic fibers described in section