JPS6128014A - Production of fiber containing acrylonitrile - Google Patents

Abstract

PURPOSE:To obtain hollow fibers using an ordinary spinneret, by drawing a filament yarn wet extruded from an acrylonitrile (AN) based copolymer solution in a hot water bath, drying the drawn yarn at a low temperature, and heat-treating the dried yarn to form single or plural cavities in the fiber cross section. CONSTITUTION:A spinning solution of an acrylonitrile (AN) based copolymer, preferably containing >=30wt%-<80wt% AN is wet spun, and the resultant yarn is drawn in a hot water bath to densify further the skin layer. The wet yarn in a state of binary structure having the skin layer and the core layer is dried at a low temperature and heat-treated to form single or plural cavities in the cross section of the fibers. Thus, 5-40% void content is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a method for producing acrylonitrile-containing fibers, in particular acrylonitrile-containing fibers that form single or multiple cavities in the cross section of the fibers.

``Prior art'' ``Problems to be solved by the invention'' In general, hollow fibers are stiff, have a low apparent specific gravity, are noble, and have many characteristics such as heat retention and water absorption. . Conventionally, when producing hollow fibers, methods such as (1) using a spinneret with a complicated structure, (2) a method of incorporating additives such as a foaming agent into the spinning solution, etc. have been used, but the method of (2) However, due to the structure of the spinneret, it is technically difficult to create fine pores, and it is difficult to obtain fine pores. In addition, it is difficult to increase the number of holes and the spinneret becomes extremely expensive, resulting in low productivity and poor profitability. On the other hand, method (2) has problems such as the dispersibility tends to be non-uniform due to the nature of the blowing agent, the spinning operation is unstable, and most of the fiber bundles are not hollow.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the inventors of the present invention have conducted intensive research to improve the drawbacks of the conventional methods as described above, and as a result they have arrived at the present invention.

That is, in the present invention, an acrylonitrile-based copolymer is dissolved in an organic or inorganic solvent to form a spinning dope, wet-spun through an ordinary spinneret to form a binary structure having a skin layer and a core layer, and then heated. Wet yarn drawn in a water bath to make the skin layer more dense is dried at low temperature while maintaining its binary structure, and then heat-treated to form single or multiple cavities in the cross section of the fiber. The subject matter is a method for producing fibers containing acrylonitrile, which is characterized in that the fibers contain acrylonitrile.

The acrylonitrile copolymer used in the present invention is a copolymer consisting of b7 or 30% by weight but not more than 80% by weight of acrylonitrile.
It is obtained by copolymerization with more than one type of vinyl monomer.

More preferably, the acrylonitrile content is 30% by weight or more60
A copolymer consisting of less than % by weight is desirable. That is, when the acrylonitrile content exceeds 60% by weight, it tends to be difficult to develop the desired binary structure during wet spinning.

Examples of vinyl monomers include acrylic acid, methacrylic acid, vinyl chloride, vinyldene chloride, vinyl esters such as vinyl acetate, vinylpyrrolidone, vinylpyridine and its alkyl substituted products, acrylic esters, methacrylic esters, and acrylic acid. Examples include amide, methacrylic acid amide, mono- and dialkyl-substituted products thereof, styrene sulfonic acid, methallyl sulfonic acid, and metal salts and amine salts thereof. In the present invention, there is no need to be very strict regarding monomers that can be copolymerized.
Any conventional vinyl monomer that can be copolymerized with acrylonitrile can be used.

This acrylonitrile copolymer is dissolved in an organic solvent such as acetone, acetonitrile, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, or an inorganic solvent such as zinc chloride, rhodan nitrate, etc. to prepare a spinning stock solution. It is also possible to use organic pigments or stabilizers effective for spinning, color prevention, light resistance, etc., as long as they do not interfere with spinning.

The conventional spinneret used in the present invention has an orifice that is circular or oval with a length ratio of major axis to minor axis smaller than 5 to 1, or polygonal such as triangular, hexagonal, or rhombic. Although it refers to a spinneret, an orifice having a circular or nearly oval shape is suitable.

The above-mentioned spinning dope is wet-spun through the spinneret as described above, and a water/8 solution containing an organic solvent or an inorganic solvent corresponding to the organic solvent or inorganic solvent present in the spinning dope, or both, is used. into a filled first coagulation bath. In order to form a skin layer, the concentration of the organic solvent, inorganic solvent, or both in the bath is preferably 1 to 1.
The amount is 50% by weight, more preferably 5 to 30% by weight, and the temperature is preferably from 0°C to -50°C, and more preferably from 0°C to +30°C. The first coagulation bath residence time is
It is set by the above concentration and temperature, as well as the fineness.
The time is preferably 2 to 80 seconds.

Next, the fibers are led to a second coagulation bath, but in order to make the skin layer more dense and to make the difference from the core layer more clear, the concentration of the organic solvent, inorganic solvent, or both in the bath must be adjusted. It is necessary to have the same concentration as the first coagulation bath, more preferably a lower concentration than the first coagulation bath, and furthermore, the temperature should be the same as the first coagulation bath, more preferably a higher temperature than the first coagulation bath. It is desirable that there be.

It is also possible to draw the fiber in this second coagulation bath, and it is preferable to impart some physical properties by drawing, but excessive drawing will densify the core and destroy the binary structure. Must be avoided due to fear. The residence time in the second coagulation bath is 2 to 2, including when stretching is performed.
80 seconds, more preferably 2 to 40 seconds. After that, the fibers are washed, usually at 10-45°C.
The washing is carried out in two steps: in water at a low temperature of 70° C. and in hot water at a temperature of 70° C. or higher, but depending on the case, the low-temperature water washing may be omitted.

After passing through this washing bath, in order to develop the desired binary structure, the temperature should be 70°C or higher, preferably 80 to 100°C.
It is necessary to stretch the film by 1.2 to 5.0 times in hot water, more preferably from 1.5 to 40 times. That is, if it is less than 1.2 times, the physical properties of the fiber will deteriorate, and if it exceeds 5.0 times, the voids in the core layer will become dense and the desired binary structure will not be maintained.

Through the above steps, a wet yarn with a water content of 100% by weight or less and a solvent content of 20% by weight or less is formed, and a two-layer structure with a dense and strong skin layer and a soft core layer with many voids is formed. can be formed.

However, heat treatment is necessary to form single or multiple cavities in the cross section of this fiber, but before heat treatment, low temperature drying, preferably 5 to 4°C, is performed to reduce the moisture content. 30% by weight or less and the solvent content is 15% by weight
It is desirable to lower it to below. Drying temperature is 40"C
If it exceeds this, the voids in the core layer will become dense and it will be difficult to maintain the two-layer structure. On the other hand, if the temperature is lower than 5°C, the drying efficiency decreases and the drying time increases, causing problems in terms of productivity.

The heat treatment referred to in the present invention includes all methods such as general dry heat treatment using hot air, moist heat treatment using steam, etc., or heat treatment using a constant temperature bath using organic compounds such as polyethylene glycol and glycerin. The object can be achieved using one or more of these methods. Also, the heat treatment temperature is 100 to 150
°C is preferable, and the higher the temperature, the better the cavity will be formed, but if heat treatment is performed at a temperature exceeding 150 °C in a dry heat system or 130 °C or higher in a moist heat system, excessive shrinkage will occur. This is not preferable because it may cut the fibers.

According to the method of the present invention, there are differences in the shape of the cavities formed depending on the type of heat treatment method, but when manufacturing fibers, it is normal for the shape of the fibers obtained depending on the heat treatment method to differ, and it is normal for the purpose The most appropriate method should be selected depending on the situation.

In this way, fibers having single or multiple cavities in the cross section of the fiber can be obtained, and the number of cavities obtained by the method of the present invention is 5 to 40%, including single and multiple cavities.
It shows the cavity ratio of .

Note that the void ratio was calculated using the following method.

A cross-sectional photograph of the fiber was projected onto paper of uniform thickness, and the ratio of the total weight of the fiber cross section (S w + Cw) and the weight of the cavity CW was determined according to the following formula.

Cavity ratio [%] = (Cw/ (Si++))X10
0 (Cw: weight of the hollow part, weight of the hollow part: weight of the non-hollow part) Moreover, the above-mentioned water content and solvent content were calculated by the following measuring method. That is, the fiber to be measured is immersed in pure water and boiled to elute the solvent, etc. in the fiber, and the amount of organic or inorganic solvent in the solution is measured by gas chromatography or the like. The fibers were taken out and dried at 115 to 120° C. for 3 hours, and the weight of the mold was measured. The weight of the pure water is Wl, and the weight of the fiber before immersion is vJ2. When the weight of the fiber after drying is W3 and the concentration of the organic solvent or inorganic solvent is C, the solvent content is calculated by the following formula.

Solvent rate S (%) = (C((W1+W2) W3)
/JX100 Furthermore, the moisture content is calculated by the following formula.

Moisture content [%] - [(匈2-匈3)/匈3) X100-
5 (%) "Examples" The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited by these in any way.

Example 1 Spinning yarn containing 30% by weight of an acrylonitrile copolymer consisting of acrylonitrile/sodium styrene sulfonate/vinyl chloride-49.5/1.0/49.5 in acetone and maintained at 45 to 55°C. Add the stock solution to the hole) 0525
Acetone containing 30% by weight in water was passed through a spinneret having a circular orifice with 100 mm holes.
wet spinning into a first coagulation bath held at °C;
It passed through a second coagulation bath which was in the same state as the coagulation bath, where it was stretched twice. At this time, the first bath residence time was 80 seconds, and the second bath residence time was 20 seconds. The film was further passed through a washing bath at 30°C, and then passed through a hot water bath at 90°C to be stretched 2.5 times. Moisture content at this stage is 74.4% by weight
, the acetone content was 16.5% by weight. then 30°
By drying C at low temperature for 6 minutes, the moisture content was 19.1.
% by weight of acetone was reduced to 12.2% by weight. The edges were subjected to a dry heat treatment step at 145°C for 5 minutes.

The fiber obtained through the above steps had a fineness of 29.7 denier and was a hollow fiber having a single cavity. A cross-sectional photograph (scanning electron microscope) of this fiber is shown in FIG.

Example 2 The same spinning dope as in Example 1 was used with a pore diameter of 0.14 mm and a number of pores of 30.
Wet-spun into a first coagulation bath similar to Example 1 through a spinneret with a circular orifice of 0 holes, followed by a second coagulation bath containing 20% by weight of acetone in water and maintained at 25°C.
It was passed through a coagulation bath where it was stretched twice. At this time, the first bath residence time was 25 seconds, and the second bath residence time was 10 seconds. Further, the water washing bath was omitted and the film was stretched in a hot water bath at 90° C. for 2.5 (i3). At this stage, the water content was 95% by weight and the acetone content was 7.9% by weight. Next, low-temperature drying at 25°C was performed for 5 minutes to reduce the water content to 28% by weight and the acetone content to 5.9% by weight.Then, the mixture was left in a glycerin bath maintained at 130°C for 2 minutes. The fineness of the fiber obtained through the above process was 6.8 denier, and its cross-sectional photograph is shown in Figure 2, which is structurally almost the same as that of Example 1 (Figure 1). We are doing so.

Example 3 The same spinning dope as in Example 1 was used with a pore diameter of 0.5 mm and a number of pores of 50.
- Wet-spun into a first coagulation bath containing 40% by weight of acetone in water and held at 45°C through a spinneret with a circular orifice of 300° C.; It passed through a maintained second coagulation bath, where it was stretched 1.4 times. At this time, the first bath residence time was 90 seconds, and the second bath residence time was 20 seconds. 30 more
3. Pass through a 90°C hot water bath after passing through a water washing bath at 'C.
Six members were extended. The moisture content at this stage is 81.
The acetone content was 16.9% by weight.

Next, by drying at a low temperature of 30° C. for 5 minutes, the water content was reduced to 23.2% by weight and the acetone content was reduced to 12.2% by weight. After that, a wet heat treatment process at 125°C]0
It was allowed to stay for a minute. The fiber obtained through the above steps had a fineness of 56.5 denier and was a hollow fiber having a plurality of cavities as shown in FIG.

Comparative Example 1 Using the same spinning dope as in Example I, a spinneret containing 30% by weight of acetone in water and maintained at 25°C was passed through a spinneret having a circular orifice with a hole diameter of 0.25 mm and 100 holes. Wet-spun into a coagulation bath 2 It passed through a coagulation bath, where it was stretched twice. At this time, the first bath residence time was 80 seconds, and the second bath residence time was 20 seconds. Further, the film was passed through a washing bath at 30°C and then a hot water bath at 90°C to be stretched 25 times.

Next, after drying at 80°C for 6 minutes, a dry heat treatment step at 145°C was carried out for 5 minutes. The fiber obtained through the above steps had a fineness of 30 denier, and no cavities were formed at all.

Fiber shape 4/ obtained in the above examples and comparative examples,
The properties are shown in Table 1.

"Operation""Effects of the Invention" The present invention has the following advantages; There is no decrease in productivity, and since it uses a normal spinneret, products with fine fineness can be easily obtained.

(2) Since no additives such as foaming agents are required, stable spinning operation can be maintained and a certain controlled cavity can be formed. (3) The process used to carry out the present invention is a normal process for manufacturing fibers and is no different from the conventional process, so it is possible to produce the fibers with high productivity and at low cost. It is possible.

Furthermore, the fibers obtained according to the present invention are suitable for the following uses. That is, it has a suitable stiffness and a dull feel, making it suitable for pile applications, and its heat retention and water absorption properties make it suitable for use in carpets, futons, and other applications.

[Brief explanation of drawings]

1 to 3 are microphotographs of 8 cross sections showing the shapes of the fibers obtained in Examples 1 to 3. 1 (〆)μm 50μm 2001jm Procedural amendment (Own ship 1. Indication of the case 1982 Patent Application No. 150357 2, Name of the invention Method for manufacturing fibers containing acrylonitrile 3, Person making the amendment Relationship with the case: Patent Applicant address: 3-2-4 Nakanoshima, Kita-ku, Osaka Name: (0
94) Kanebuchi Chemical Industry Co., Ltd. Representative: Representative Director Takashi
1) The description in the "Detailed Description of the Invention" column of the specification of Sho 4, agent address: 3-2-4 Nishitenma, Kita-ku, Osaka, is amended as above; (1) Pages 5, 8- On the 9th line, "Nitric acid, Rodan salt J" is corrected to "nitric acid, Rodan salt." (2) On the same page, on the 11th line, "Stabilizers, etc." is corrected to "Stabilizers, etc." do. (3) On the 6th page, line 8, the phrase "0°C to +30°C" is corrected to "0°C to -30°C." (4) On the same page, in the 5th line from the bottom, ``Dere katoka'' is corrected to ``Dere ga''. (5) On page 7, in the second line, the phrase "core" is corrected to "core layer". (6) On the same page, in the 8th line, the phrase "low-temperature water cleaning" is corrected to "one or both." (7) On the same page, in the 12th line, replace r 1.2 J with “1”
．． (8) On the same page, in the 14th line, "1.2 times" should be changed to "1.
(9) On page 8, in the first line, the words "two-layer structure" are corrected to "two-layer structure." (10) On the same page, in the 8th line, the words "two-layer structure" should be corrected to "two-layer structure." (11) On the same page, in the 13th line, "polyethylene glycol" is corrected to "polyethylene glycol." (12) On page 9, the fourth line from the bottom says “hollow part”.
In addition, the words "non-hollow part" in "Cavity part" should be corrected to "non-hollow part." (13) On page 10, line 4, "weight after drying" is corrected to "weight after drying". (14) On the same page, in the 9th line, replace “/W” with “/W3
(15) In the 7th line from the bottom of the same page, the words "present invention" are corrected to "the present invention." (16) On page 11, line 12, next to “acetone” “
Insert "for the content rate." (17) On page 15, at the bottom of the table, correct "r 59. OJ" to "30.0".

Claims (1)

[Claims] 1. An acrylonitrile-based copolymer is dissolved in an organic or inorganic solvent to obtain a spinning dope, and wet-spun through a normal spinneret to form a binary structure having a skin layer and a core layer; Next, the wet yarn, which has been drawn in a hot water bath to make the skin layer more dense, is dried at a low temperature while maintaining the binary structure, and then heat-treated to create single or multiple cavities in the cross section of the fiber. A method for producing fibers containing acrylonitrile, characterized by forming acrylonitrile. 2. The production method according to claim 1, wherein the acrylonitrile copolymer contains 30% by weight or more and less than 80% by weight of acrylonitrile. 3. In wet spinning, the solvent concentration of the first and second coagulation baths is 1 to 50.
% by weight, a temperature of -10 to 50°C, and a residence time of 2 to 80 seconds. 4. The manufacturing method according to claim 1, wherein the stretching in a hot water bath is performed by stretching 1.1 to 5.0 times in hot water at 70°C or higher. 5. The manufacturing method according to claim 1, wherein the low-temperature drying is performed at a temperature of 5 to 40°C. 6. The manufacturing method according to claim 1, wherein the heat treatment is carried out at a temperature of 100 to 150°C.