JPS6190708A - Production of acrylic hollow fiber - Google Patents

Abstract

PURPOSE:To obtain an acrylic hollow fiber having excellent bulkiness, compressive elasticity, water retentivity and heat insulating characteristic by setting the discharge angle of a raw liquid for spinning at 20-40 deg. relative to a nozzle plane and spinning draft ratio at 0.9-1.5. CONSTITUTION:The copolymer contg. 50-97wt% acrylonitrile is dissolved in an org. solvent such as DMF, DMA or DMSO to prepare the raw liquid for spinning. The shape of the spinning orifice is made into a triangular shape and the discharge angle is required to be set at 20-40 deg. relative to the nozzle plane. The raw liquid is wet spun at 0.9-1.5 spinning draft ratio into a solidifying bath of an aq. solvent soln. of an acrylonitrile copolymer contg. >=55wt% water. The spun fiber is in succession subjected to stretching, drying and relaxation treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel method for producing acrylic hollow fibers.

[Conventional technology]

Conventionally, the method for manufacturing acrylic hollow fibers is (
1) A method of spinning by using a core-sheath spinning nozzle to supply an acrylic polymer spinning stock solution to the sheath part and a coagulant or a spinning stock solution that can be eluted in a subsequent process to the core part (Japanese Patent Publication No. 57-5344
(No. 8), (21 A method of spinning by making the orifice shape of the spinning nozzle hollow or horseshoe-shaped, (3) containing a compound that is poorly soluble or insoluble in water and has a low boiling point as a blowing agent. A method of spinning an acrylic polymer spinning stock solution and evaporating the blowing agent in the washing/stretching process or drying process (Japanese Patent Publication No. 58-38532), (4) High molecular weight soluble in acrylic polymer solvent and water. A method has been proposed in which an acrylic polymer spinning dope containing a compound is spun, and the high molecular weight compound is eluted in a coagulation bath and a washing tank (Japanese Patent Application Laid-Open No. 57-210011).

Among these methods, method (1) yields continuous and highly accurate homogeneous hollow fibers, but the spinning nozzle is quite complex and it is impossible to increase the number of holes, so productivity cannot be increased. Naturally, it becomes expensive. Method (2) is different from method (1), but similarly to method (1), the spinning nozzle cost is high and it is somewhat difficult to increase the number of holes. In method (3), there is a problem with the dispersion stability of the blowing agent in the normal method, and adding a surfactant to improve the dispersion stability improves the dispersion stability, but the recovery of the surfactant is difficult. It becomes necessary. It has also been proposed to blend an acrylic copolymer copolymerized with a monomer containing this surfactant component, but although this improves dispersion stability and eliminates the need to recover the surfactant, it still causes evaporation and vaporization. There remains a need to recover the blowing agent. Furthermore, the fibers obtained in this way are more appropriately called porous fibers than hollow fibers, and they lack compressive elasticity.

Method (4) is almost the same as (3), and it is necessary to recover the compounds eluted in the coagulation bath and washing process, and the resulting fibers have a porous structure, so they lack compressive elasticity. There are some problems.

[Problem that the invention seeks to solve]

The present invention is a simple and inexpensive acrylic hollow fiber that has excellent bulkiness, compressive elasticity, water retention, and heat retention, and does not have the above-mentioned disadvantages, and can be expected to be used in a wide range of products. The aim is to establish a new method for producing fibers.

[Failure to solve the problem]

The gist of the present invention is that when a spinning dope of a copolymer containing 50% by weight or more of acrylonitrile is extruded into a coagulation bath through a triangular orifice to form fibers, the discharge angle of the spinning dope is adjusted relative to the nozzle surface. te20~4
0°, spinning draft ratio of 0.9 to 1.5, and extruded into an aqueous solvent solution containing 55% by weight or more of water to produce an acrylic material with an irregular fiber cross section and discontinuous hollow parts inside the fiber. The objective is to produce hollow fibers based on the system.

The present invention will be explained in more detail below.

The acrylonitrile copolymer used in the present invention includes 50 to 97% by weight of acrylonitrile, unsaturated monomers copolymerizable with acrylonitrile, such as acrylic acid or methacrylic acid and their derivatives, vinyl chloride, vinyl bromide, Acrylamide, methacrylamide, vinylidene chloride.

Vinyl acetate or sodium vinylbenzenesulfonate,
It consists of a copolymer consisting of 3 to 50 weight percent of one or more ionic unsaturated monomers such as sodium mecrylsulfonate.

As the spinning solvent for spinning these, organic solvents such as dimethylformamide, dimethylacetamide, and dimethyl sulfoxide are preferable.

The shape of the spinning orifice and the direction in which the spinning dope is discharged are important factors in order to obtain the acrylic hollow fibers that are the object of the present invention. When discharging through the orifice, the discharge angle is 20 to 4 with respect to the nozzle surface.
It must be 0'.

Still other conditions include wet spinning at a spinning draft ratio of 0.9 to 1.5 in a coagulation bath of a melting ice solution of the acrylonitrile-based copolymer containing 55% by weight or more of water. That's true.

Although various shapes of the orifice other than a triangle are conceivable for manufacturing hollow fibers, a triangle is preferable because the orifice processing cost is relatively low and the effects of the present invention can be maximized.

During spinning, if the discharge angle of the spinning stock solution exceeds 40°, the amount of hollow portions generated will decrease, and if it is less than 20°, the spinning stock solution discharged from the spinning orifice will tend to adhere, making spinning impossible. Furthermore, if the water composition in the coagulation bath is less than 55% by weight, the cross-sectional form of the obtained fiber will be simply circular and no hollow portions will be generated at all, and even if the spinning draft ratio is less than 0.9, the amount of hollow portions will be generated. decreases, and as the spinning draft ratio decreases, the cross-sectional shape of the fiber becomes circular or close to a broad bean shape. As described above, the higher the spinning draft ratio is, the larger the hollow portion of the acrylic hollow fiber is, which is the object of the present invention. However, if the spinning draft ratio exceeds 1.5, the operational stability in the subsequent drawing process will be affected. Less desirable.

The undrawn fibers drawn out from the coagulation bath are then drawn and
Wash, dry, and soften. Although these methods are not particularly limited, the present inventors used 4 to 6
After stretching and washing at the same time, the film was dried under tension on heated rolls at 110 to 150°C, and then shrunk by 15 to 35% with saturated steam at 100°C or higher.

The fibers obtained according to the present invention contain pipe-like hollow parts, although they are discontinuous, and therefore have excellent bulkiness, compressive elasticity, water retention, and heat retention.

〔Example〕

The present invention will be specifically explained below using examples.

Example: A copolymer consisting of 93% by weight of acrylonitrile and 7% by weight of vinyl acetate (intrinsic viscosity 1.35 in dimethylformamide at 25°C) was mixed with dimethylacetamide (hereinafter referred to as DMAc) to a concentration of 24% by weight using a conventional method. It was dissolved in water, filtered and defoamed to obtain a spinning stock solution. One side of this spinning dope is 0.
30% DMAc and 70% water are passed through a spinning nozzle with 200 holes in which 12 equilateral triangular orifices are arranged radially.
When extruding the spinning dope into a coagulation bath at 40°C consisting of
Changes were made within the range of ° as shown in Table 1. Subsequently, the film was stretched 5.0 times in hot water, washed, and dried at 140'C. Subsequently, the fibers were subjected to relaxation treatment in saturated steam at 135° C. to obtain fibers having a fineness of 3 d/f, 1.

Table 1 shows the cross-sectional morphology of the fibers thus obtained. As is clear from the table, the discharge angle is 20° to 40°.
It is necessary to be within the range of .

Table 1 Example 2 Using the same spinning dope and spinning nozzle as in Example 1, the coagulation bath composition was changed as shown in Table 2 when spinning at an angle of 30° to the spinning nozzle surface. Coagulation bath temperature, spinning draft ratio, stretching, washing.

The drying and relaxation treatment conditions were the same as in Example 1. Table 2 shows the cross-sectional morphology of the fibers thus obtained.

As is clear from the table, the coagulation bath must contain 55% by weight or more of water.

Table 2 *Weight Ratio Example 3 Using the same spinning stock solution as in Example 1, 30% DMA c and water were passed through a spinning nozzle with 200 holes in which equilateral triangular oriswises were arranged radially as shown in Table 3. The spinning dope was extruded into a coagulation bath of 70% coagulation bath at 40°C at a discharge angle of 30' with respect to the spinning nozzle surface. At this time, each.

In the case of the spinning nozzle, change the spinning stock solution discharge amount,
The spinning draft ratio was as shown in Table 3. The stretching, washing, drying, and relaxation treatment conditions were the same as in Example 1. Table 3 summarizes the cross-sectional morphology of the fibers thus obtained.

As is clear from Table 3, the spinning draft is 0.9 to 1.5.
The acrylic hollow fibers that are the object of the present invention can only be obtained within this range. If the spinning draft ratio is less than 0.9, the amount of hollow portions generated will be extremely small, and if it exceeds 1.5, the spinning stability will deteriorate, and in particular, stretching breakage will occur frequently.

Example 4 Using the same spinning dope as in Example 1, the − side was 0 and 20 m.
10 holes with m equilateral triangular orifices arranged radially
DMAc 30%, water 70% through a spinning nozzle of 000
The spinning dope was extruded into a coagulation bath at 40° C. consisting of 100% of the spinning solution at a spinning draft ratio of 0.93 such that the discharge angle was 30° with respect to the spinning nozzle surface.

Subsequently, stretch and wash in hot water 5.0 times
It was dried at ℃ and crimped by a known method. Subsequently, the fibers were relaxed in saturated steam at 135°C and the crimp was heat set, and then cut to 10 d/fsl.
A raw cotton having a fineness of 152πn in length was obtained.

As a comparative example, spinning was carried out in exactly the same manner as in Example 4, except that a circular orifice of 0.15 wnφ was used and the spinning draft ratio was set to 0.95.

Stretching, washing, drying, crimping, relaxation treatment and cutting were carried out to obtain raw cotton having a length of 152 nm and a fineness of 'Od/ftx.

The obtained raw cotton had an amorphous cross section and a pipe-shaped hollow part, although it was discontinuous.

On the other hand, in the comparative example, the spinning oriswiss shape was only circular, the spinning draft ratio was almost unchanged, and the other conditions were exactly the same, but the cross-sectional shape was bean-shaped and there was no hollow part at all.

Therefore, the raw cotton obtained in the example of the present invention was superior in bulkiness, compressive elasticity, water retention, and heat retention compared to the raw cotton of the comparative example.

〔Effect of the invention〕

The method of the present invention makes it possible to produce a novel acrylic hollow fiber having excellent bulkiness, compressive elasticity, water retention, and heat retention.

[Brief explanation of the drawing]

Figure 1 is a scanning electron micrograph of the cross section of the fiber of Example 4 (
(magnification: 750 times). Figure 2 shows the side view of the fiber of Example 4, which is an example of the present invention, immersed in tweeder oil. This is a photograph taken using an O0x optical microscope. The black part indicates the hollow part. Although it is discontinuous in this way, it can be seen that it contains a considerable amount of hollow space. λ2 Diagram Procedural Amendment (Method) % Formula % 2, Name of the invention Method for manufacturing acrylic hollow fiber 3, Relationship with the person making the amendment Patent applicant 2-3-19 Kyobashi, Chuo-ku, Tokyo (603 ) Mitsubishi Rayon Co., Ltd. President Akio Kawasaki 4, Agent 2-3-19 Kyobashi, Chuo-ku, Tokyo January 9, 1985 (Delivery date: January 29, 1985) Correct it accordingly. 1) Insert "schematic diagram" next to "(magnification: 750x)" in the bottom two lines of page 14. 2) On page 15, line 2, insert ``Schematic diagram'' after ``What we did''. 2. Revise the drawing to be appropriate as shown in the attached sheet.

Claims (1)

[Claims] When extruding a spinning dope of a copolymer containing 50% by weight or more of acrylonitrile into a coagulating liquid through a triangular orifice to form fibers, the spinning dope is discharged at an angle of 20 to 40° with respect to the nozzle surface, and the spinning draft ratio is adjusted. 0.9
A method for producing an acrylic hollow fiber having an amorphous fiber cross section and a discontinuous hollow portion inside the fiber, the fiber being extruded into an aqueous solvent solution containing 55% by weight or more of water as ~1.5.