JPH0478727B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing ultrafine fibers, and more specifically, by obtaining an aggregate of ultrafine fibers containing a plurality of fiber shapes in one fiber by a wet method or a dry method, and then dividing this. The present invention relates to a method for producing ultrafine fibers. Although one fiber has a normal fineness (2 denier to 50 denier), the fiber is cotton, spun yarn,
It is widely known that the separation into ultrafine fibers at the stage of final products such as nonwoven fabrics and knitted fabrics has unique value not only in terms of the texture and feel of the product, but also in terms of physical properties. However, in order to obtain such fibers, a method called a polymer array production method using a special composite spinneret was used (Japanese Patent Publication No. 18369, 1973).
There are also those with a built-in static mixer in the spinneret (Japanese Patent Application Laid-open No. 56-91069), which require a sophisticated and expensive spinneret, and two different resins must be introduced separately to the spinneret. The current situation is that complex processes and equipment are required. On the other hand, it has also been announced that yarns with sea islands can be obtained by utilizing microphase separation of different types of polymers, but this is not as complete as the former method, nor is it practical. That is, it is very important that the threads formed in the islands are formed into perfect fiber shapes, and this determines the value of the final product. In this sense, the method for producing a polymer array using a special spinneret allows obtaining a sea-island shape that is close to the ideal, and also allows the island portions to form a nearly perfect fiber shape. However, as mentioned above, this method requires an expensive spinneret,
The problem is that the process is complicated. On the other hand, compared to this, the method that applies microphase separation is simple and advantageous, but the formation of threads in the island portion is not sufficient and it is difficult to form a perfect fiber shape, so the characteristics are fully exhibited even in the final product. The current situation is that this has not been done. In view of these circumstances, the present inventors have conducted intensive research in order to obtain synthetic fibers with a perfect sea-island structure in cross section, without requiring a special spinneret or complicating the manufacturing process, and to obtain ultrafine fibers from the fibers. As a result of repeated efforts, we have arrived at the present invention. That is, the present invention uses 20 to 80 parts by weight of an acrylic resin composition containing acrylonitrile as a main component and 80 parts by weight of a vinyl chloride resin and/or a chlorinated vinyl chloride resin composition having a chlorine content of 68 percent by weight or less. 20 parts by weight are mixed and dissolved in a common solvent, spun into a coagulating liquid in which the resin composition is solidified or into air, stretched and dried to obtain an aggregate of ultrafine fibers, and then the aggregate is divided. The content is a method for producing ultrafine fibers characterized by the following. The acrylic resin composition used in the present invention contains 30 to 85 weight percent of acrylonitrile, and a vinyl compound having copolymerizability with this, such as methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinylidene chloride, In addition to styrene, sodium methalylsulfonate, sodium p-styrenesulfonate, itaconic acid, etc., which are used as dye improving agents, may also be copolymerized. The acrylic resin composition in the present invention includes a so-called acrylic resin composition,
Acrylic resin compositions usually contain acrylonitrile.
85% by weight or less and 30% by weight or more of vinyl chloride and/or vinylidene chloride from 15% by weight or more and 70% by weight or less, and a dyeing improver that can be copolymerized with this, such as sodium metaallylsulfonate, sodium p-styrenesulfonate, It is composed of less than 2% by weight of itaconic acid and the like. The effect of these resin compositions is significant when the amount is from 20 parts by weight to 80 parts by weight, and more preferably from 30 parts by weight to 50 parts by weight. On the other hand, if the amount is less than 20 parts by weight or exceeds 80 parts by weight, the fiber shape of the island portions will be incomplete, making it difficult to express the characteristics thereof, and the value of the final product will also decrease. The chlorinated vinyl chloride resin composition used in the present invention preferably has a chlorination rate of up to 68% by weight, and a 25% by weight acetone solution of this composition at 25°C ranges from 1 poise to 20% by weight.
Anything up to a point is good. Outside these ranges,
In either case, the fiber shape of the island portion becomes incomplete. More specifically, the chlorine content is preferably from 61% to 65% by weight, and in this case the fibers in the island portions exhibit the best shape. Also, among the general commercially available vinyl chloride resin compositions, those with a polymerization degree of 700 to 1500 are good; those with a degree of polymerization lower than this have poor fiber shape in the island portion, and those with a degree of polymerization higher than this are not uniformly blended. I don't like it because it's difficult. Next, when mixing and dissolving these acrylic resin compositions and vinyl chloride and/or chlorinated vinyl chloride resin compositions, there is no particular restriction as long as the solvent is a common solvent that dissolves each resin composition, and there are no particular restrictions on the dissolution method. They may be dissolved separately and mixed together.
Alternatively, the respective resin compositions may be simultaneously introduced into a common solvent and dissolved by stirring. The melting conditions (temperature and time) during this melting do not seem to have much effect on the fiber shape of the island portions. When the spinning stock solution obtained in this way is spun by a wet spinning method, it can be discharged from a common spinneret into a coagulating solution and coagulated to form fibers. Furthermore, in order to increase the strength of the fiber, it is effective to stretch the fiber several times in a spinning bath, and then dry it to obtain a synthetic fiber. In this case, it is also possible to carry out hot drawing or heat treatment under conditions suitable for the fiber, and the yarn structure of the synthetic fiber will not be significantly changed by this. On the other hand, in the so-called dry spinning method, which involves spinning into a hot air atmosphere, the desired synthetic fiber can be obtained in the same way as in the wet spinning method, but the fiber surface is essentially different from the wet spinning method, except that the fiber surface is slightly smoother. do not have. The synthetic fiber made of an aggregate of ultrafine fibers thus obtained is divided into ultrafine fibers. When you look at one of these synthetic fibers, its appearance is almost the same as a normal fiber, but it is susceptible to external forces (tearing,
If the fiber is subjected to a process such as beating) or treated with a solvent that dissolves only the sea portion, threads with multiple fiber shapes will emerge from a single fiber. In other words, although the method utilizes phase separation, as is clear from the examples described below, surprisingly, the yarn portion of the island part has an almost perfect fiber shape, and the fineness is fine (from 2 to 2). If the fineness is 3 denier), several tens of microfibers can be obtained, and if the fineness is even thicker (30 to 50 denier), several hundred ultrafine fibers can be obtained. Further, the fibers made of the above-mentioned aggregate of ultrafine fibers can also be made into ultrafine fibers by dividing or raising them at the stage of spinning yarn or fabric. For example, when used as cotton, excellent heat retention can be expected due to the improved air content due to division, and when used as a filter,
It can remove very fine dust. In addition, the bulkiness and the extremely soft texture unique to ultra-fine fibers,
The tactile sensation is obtained by raising or dividing the yarn, nonwoven fabric, or general woven fabric at the stage. Furthermore, since the synthetic fiber is a chlorine-containing resin composition, it also has flame retardant properties, making it extremely convenient for applications such as filters. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but it goes without saying that the present invention is not limited in any way by these examples. Example 1 In a mixture of acrylic resin and chlorinated vinyl chloride resin, five types of fibers having different mixing ratios were wet-spun, and the characteristics of the obtained fibers were observed. The composition of the acrylic resin used was acrylonitrile/vinyl chloride/sodium p-styrene sulfonate weight ratio = 45.0/54.5/0.5, and the chlorinated vinyl chloride resin had a chlorine content of 62.0% by weight. Both resins were separately treated with solvent acetone.
After stirring and dissolving at 50°C to make a 25 weight percent solution, the acrylic resin/chlorinated vinyl chloride resin weight ratio was (A) 10/90, (B) 30/70, (C) 50/50, respectively.
They were mixed at a ratio of (D) 70/30 and (E) 90/10, and stirred thoroughly again to obtain a spinning stock solution. Although each spinning stock solution was slightly opaque, it was macroscopically uniform and was a stable solution that did not separate even if left standing. Each stock solution was spun, washed with water, dried, and heat treated according to the following spinning conditions, and the single fiber fineness was approximately 3 denier.
Filaments with a filament number of 50 were obtained. That is,
The spinning dope was passed through a nozzle with a hole diameter of 0.1 mm and 50 holes to be spun into a first coagulation bath of a 30 weight percent acetone aqueous solution at 25° C., and pulled up at a rate of 5 m/min.
followed by a second solution of 20 weight percent acetone in water.
Pass through a coagulation bath and a third coagulation bath of 100% water in sequence,
It was dried at an ambient temperature of 130°C and wound at a speed of 10 m/min. In the stretching process, it is stretched 3 times at 120℃, then 130℃
Relaxation treatment was performed for 10 minutes. The characteristic values of the obtained fibers are shown in Table 1. Measurement is JIS L-1069
In accordance with the above, the test was carried out in a constant speed tension type.

[Table] Regarding the sample fiber (B), the fiber was torn in the fiber axis direction to obtain ultrafine fiber. An electron micrograph of the side surface in this case is shown in FIG. 1a, and an enlarged photograph of the same is shown in FIG. 1b. The cut surface of the fiber (B) cut with a sharp knife is shown in FIG. 2a, and an enlarged photograph of the same is shown in FIG. 2b. It is clear from these that ultrafine fibers are obtained by microphase separation. The diameter of these microfibers is up to 1μ. Fibers (C) and (D) also had qualitatively similar fibers, although there was a slight difference in the degree of ease of ultrafine division. Electron micrographs of the side surface and cross section of the fiber (A) used as a control are shown in FIGS. 3 and 4, respectively. In this case, the volume occupied by the island portion is small, and a fiber shape with sufficient length is not obtained. (E)
The fibers also had the same side and cross-sectional shapes as the (A) fibers, except that the sea islands were reversed. From the above results, it can be seen that ultrafine fibers can be easily obtained according to the present invention without impairing the properties inherent to the resin. Example 2 Dry spinning was carried out in the following manner. The composition of one of the resins used was acrylonitrile/vinyl acetate/sodium metaallylsulfonate weight ratio =
90.0/9.5/0.5, and the other resin is a commercially available vinyl chloride resin. The two resins were mixed and stirred in powder form, and then dissolved in dimethyl formamide, a solvent, with stirring to form a solution with a concentration of 30% by weight, which was used as a spinning dope. The weight ratio of acrylic resin/vinyl chloride resin is (F)10/90, respectively.
(G) 30/70, (H) 50/50, (I) 70/30 and (J) 90/10. Although each spinning stock solution was slightly opaque as in Example 1, it was macroscopically uniform and stable. Spinning was carried out in the following manner, and the obtained fiber was a multifilament with 48 filaments and a total denier of 150 deniers. Discharge speed of spinning dope 43
cc/min, pore size in hot air of 210℃ at discharge temperature 145℃
A fiber shape was formed by discharging from a 0.1 mm nozzle with 48 holes, and the fiber was wound at 100 m/min. Next, this was stretched about 5 times at 110°C to obtain a fiber with a single fiber fineness of about 3.1 denier. Table 2 shows the characteristic values of each fiber.

[Table] The sample fiber (H) was torn in the fiber axis direction to produce ultrafine fibers. An electron micrograph of the side surface in this case is shown in FIG. 5, a cross section cut by a sharp knife is shown in FIG. 6a, and an enlarged photograph of the same is shown in FIG. 6b. It is understood that, like Example 1, it has the basic property of being easily formed into ultrafine fibers. (G) and (I)
The side surface and cross section of the fiber were qualitatively similar to those shown in FIGS. 5 and 6 a and b, respectively, although there were differences in the proportions of sea and island portions depending on the mixing ratio. Electron micrographs of the side surface and cut surface of the fiber (F) used as a control are shown in FIGS. 7 and 8, respectively. In this case, as in Example 1, no ultrafine fibers were obtained. The (J) fiber also had the same side and cross-sectional shape as the (F) fiber, except that the sea islands were reversed.

[Brief explanation of the drawing]

Figures 1a and b are electron micrographs showing the shape of ultrafine fibers obtained by fiberizing a mixture of an acrylic resin composition and a chlorinated vinyl chloride resin composition by a wet spinning method and tearing the mixture; b is the first
Electron micrographs showing the shape of the fibers on the cut surface obtained by cutting the fibers corresponding to the figure with a sharp knife, Figures 3 and 4 respectively show the shapes of the fibers that have not been made into ultra-fine fibers (control). FIG. 5 is an electron micrograph showing the shape of ultrafine fibers obtained by dry spinning a mixture of an acrylic resin composition and a vinyl chloride resin composition and tearing the mixture, FIG. 6 a and b is an electron micrograph showing the shape of the cut surface of the fiber corresponding to Fig. 5;
FIG. 8 and FIG. 8 are electron micrographs showing the shape of fibers that have not been made into ultrafine fibers (control).

Claims (1)

[Claims] 1. 20 to 80 parts by weight of an acrylic resin composition containing acrylonitrile as a main component and 80 parts by weight of a vinyl chloride resin and/or a chlorinated vinyl chloride resin composition having a chlorine content of 68 percent by weight or less. % to 20 parts by weight are mixed and dissolved in a common solvent, and this is spun into a coagulating liquid in which the resin composition is coagulated or into air,
A method for producing ultrafine fibers, which comprises stretching and drying to obtain an aggregate of ultrafine fibers, and then dividing the aggregate. 2 The acrylonitrile of the acrylic resin composition is 85
The manufacturing method according to claim 1, wherein the acrylic resin composition has a weight percent or less. 3. The manufacturing method according to claim 2, which uses a chlorinated vinyl chloride resin composition having a chlorine content of 61 weight percent or more and 65 weight percent or less.