JP4817597B2 - Method for producing thermoplastic synthetic fiber - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic synthetic fiber. More specifically, a method for producing a thermoplastic synthetic fiber having high strength and excellent workability by thermally stretching and / or heat-treating a fiber comprising a thermoplastic synthetic polymer having heat-fusibility at a high temperature. It is about.

  In recent years, the market demand for thermoplastic synthetic fibers has been advanced, and in particular, the demand for the physical properties of high strength and high elastic modulus has increased. For this reason, for example, in the case of wholly aromatic polyamide fiber or wholly aromatic polyester fiber, fiber properties are improved by hot stretching at a high temperature or heat treatment for a long time. In addition, with the recent increase in the yarn production speed, the temperature of the heat drawing and / or heat treatment has increased.

  However, when the drawing and / or heat treatment is performed at such a high temperature as described above, the yarn is remarkably softened and a fusing phenomenon occurs between the single fibers. In particular, when the number of filaments in the yarn is increased, the fusion is increased, and not only the yarn-making property is lowered, but also the obtained fiber is remarkably low in flexibility.

  In order to improve such problems, Japanese Patent Application Laid-Open No. 53-14781 discloses a water-soluble inorganic acid, an inorganic salt, or an aqueous solution of an inorganic salt as a non-fusible substance in advance during hot stretching or heat treatment at a high temperature. Metal halide, metal sulfate, metal nitrate, orthophosphoric acid or sodium orthophosphate, a method of applying an aqueous emulsion of an aliphatic polymer, Japanese Patent Application Laid-Open No. 58-54021 discloses a non-fused material. A method for applying a hydrated gel-forming inorganic compound, Japanese Patent Application Laid-Open No. 59-163425, a method for applying a mixture of a colloid of a hydrophilic gel-forming inorganic compound and a hydrophobic colloid as a non-fused material, Japanese Laid-Open Patent Publication No. 59-179818 proposes a method of imparting a hydrophilic gel-forming inorganic compound colloid and a surfactant. However, in these methods, a large amount of the non-fused material applied to the fiber remains after hot drawing and / or heat treatment, so that scum is easily generated when twisting the obtained fiber. When used as a fiber, there is a disadvantage that an undesirable effect appears in terms of workability, such as the adhesiveness with a matrix resin tends to decrease.

  In order to improve the workability problem, Japanese Patent Application Laid-Open No. 62-149934 uses an inert inorganic fine powder and, after stretching or heat treatment, a water application treatment and an air flow injection treatment to give fibers. A method of removing the applied inorganic fine powder has been proposed. However, it is difficult to remove the inorganic fine powder to such an extent that the workability can be improved to a sufficient level only by using the water application treatment and the air flow injection treatment together. Of course, if this method is repeated many times, the remaining amount can be reduced, but there is a problem that productivity is lowered and cost is increased.

Thus, the actual situation is that no wholly aromatic polyamide fiber that has excellent processability in various post-processing steps and can provide a high-performance product has not yet been proposed.
JP-A-53-147811 JP 58-54021 A JP 59-163425 A JP 59-179818 A JP-A-62-149934

  The present invention has been made against the background of the above-described prior art, and its purpose is to provide excellent yarn-making properties because fusion between single fibers is prevented during hot drawing and / or heat treatment at high temperatures. And it is providing the manufacturing method from which the thermoplastic synthetic fiber which expresses the outstanding workability in a twisted yarn or a weaving process is obtained.

According to the study of the present inventor, the above-mentioned problem is as follows: “ Inactive hydrophilic inorganic of anhydrous aluminum silicate and / or sodium aluminosilicate having a degree of aggregation of 2.0 or less on a fiber comprising a thermoplastic synthetic polymer. A method for producing a thermoplastic synthetic fiber, comprising: applying an aqueous dispersion of fine powder , followed by hot stretching and / or heat treatment at a high temperature, and then removing the inorganic fine powder adhering to the fiber. Has been found to be achieved.

  The fiber made of a thermoplastic synthetic polymer in the present invention refers to an undrawn yarn, a partially drawn yarn or a drawn yarn of a thermoplastic synthetic fiber that can be hot drawn or heat treated. In the present invention, among such thermoplastic synthetic fibers, various synthetic fibers that are hot-drawn and / or heat-treated at a high temperature that causes fusion between single fibers are targeted. Examples include polyparaphenylene terephthalamide fiber, copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber, polyparaphenylene benzoxazole fiber, high strength polyethylene fiber, high strength polyvinyl alcohol fiber, wholly aromatic polyester fiber. Etc. can be illustrated. Among these, copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber is obtained by heating an undrawn yarn to a high temperature of 300 ° C. or higher, preferably 350 to 550 ° C. in order to obtain a high tenacity fiber 6 times. Since it is necessary to heat-draw as described above, the single fibers are softened and fused to each other, and the drawability is likely to deteriorate.

In the present invention, it is necessary to first apply an aqueous dispersion of anhydrous aluminum silicate and / or sodium aluminosilicate, which is an inert hydrophilic inorganic fine powder, to unstretched fibers made of the above thermoplastic polymer. The term “inert” as used herein means that it is chemically stable even at a high temperature during heat drawing and / or heat treatment and does not exert a chemical action such as oxidation on the synthetic fiber. The hydrophilic inorganic fine powder here refers to anhydrous aluminum silicate and / or sodium aluminosilicate that does not require a dispersant or a surfactant when preparing an aqueous dispersion of the fine powder. In the case of inorganic fine powders that do not have hydrophilicity, a dispersant or surfactant such as sodium hexametaphosphate is required when preparing an aqueous dispersion, and these additives are collected or used for waste liquid treatment It is that Do not required. In addition, when an organic dispersant is used, it is not environmentally preferable because it is scattered into the atmosphere at a high temperature during stretching and / or heat treatment.

Further, the anhydrous aluminum silicate and / or sodium aluminosilicate used in the present invention has a cohesion degree of 2.0 or less . When the degree of aggregation exceeds 2.0, the inorganic fine powder is likely to block on the fiber surface during hot stretching and / or heat treatment at a high temperature. not only no longer express, the inorganic fine powder adhering to the fiber surface after hot drawing and / or heat treatment, that Do is difficult even removed trying removed by a method described later.

  The degree of aggregation (G) here means the average particle diameter (dμm) of the inorganic fine powder measured by the particle size distribution meter of the aqueous dispersion containing the inorganic fine powder, and the aqueous dispersion is dried at 110 ° C. for 1 hour. The ratio (D / d) with the average particle diameter (D μm) measured again as an aqueous dispersion.

The anhydrous aluminum silicate and / or sodium aluminosilicate used in the present invention preferably has a water absorption of 20 to 350 ml / 100 g, particularly 40 to 250 ml / 100 g. When the water absorption is less than 20 ml / 100 g, the sedimentation rate of the inorganic fine powder in the aqueous dispersion is remarkably increased, so that it is difficult to maintain a uniform aqueous dispersion. On the other hand, when the amount of water absorption exceeds 350 ml / 100 g, it is necessary to reduce the concentration of the aqueous dispersion in order to uniformly adhere the inorganic fine powder to the fiber surface. Will occur. Furthermore, since the inorganic fine powder swells in the aqueous dispersion, it becomes easy to form a layer of an inorganic compound on the fiber surface during heating, and it is difficult to remove the inorganic fine powder from the fiber surface after stretching and / or heat treatment. Become.

The amount of water absorption (O) here is a value determined by the following method. That is, the inorganic fine powder is dried at 105 ° C. for 1 hour, then allowed to cool to room temperature in a desiccator, and the weight (Wg) is measured. Next, water is dropped onto the fine powder using a burette, and the amount (Vml) of the dripped water is measured just before the absorbed inorganic fine powder becomes suddenly soft. The amount of water absorption was calculated from the following equation.
O = V / W × 100

In addition to the above requirements, the anhydrous aluminum silicate and / or sodium aluminosilicate used in the present invention should have a particle size as small as possible in order to sufficiently diffuse between the single fibers and uniformly adhere to the surface of the single fibers. The average particle size is preferably 5 μm or less, particularly 3 μm or less.

Further, the anhydrous aluminum silicate and / or sodium aluminosilicate preferably has a Mohs hardness of 5 or less, particularly 4 or less. When the hardness exceeds 5 in Mohs hardness, when performing hot stretching and / or heat treatment at a high temperature, wear degradation of equipment surface tends to increase.

In the present invention , anhydrous aluminum silicate and / or sodium aluminosilicate is used.

As a method for applying the anhydrous aluminum silicate and / or sodium aluminosilicate in fibers previously anhydrous aluminum silicate and / or fine powders of sodium aluminosilicate prepared dispersion bath are dispersed in a dispersion medium such as water, dispersible fibers Drying is preferably performed after immersion in a bath. Na us, or adding a dispersing aid of an organic or inorganic in order to perform the dispersion of the fine powder uniformly in a dispersion bath, or a combination of an antistatic agent and a thickener to improve the convergence of the yarn May be.

The adhesion amount of anhydrous aluminum silicate and / or sodium aluminosilicate to the fiber is 0.3 to 2.5% by weight, preferably 0.7 to 1.5% by weight. When the adhesion amount is less than 0.3% by weight, it becomes difficult to sufficiently suppress the fusion between the single fibers at the time of hot drawing at high temperature and / or heat treatment. On the other hand, when the adhesion amount exceeds 2.5% by weight, in the step of removing anhydrous aluminum silicate and / or sodium aluminosilicate adhering to the fiber after hot drawing and / or heat treatment at high temperature, The removal efficiency at the time of removing the anhydrous aluminum silicate and / or sodium aluminosilicate remaining in the steel is lowered, and the removal equipment needs to be enlarged.

Next, most of the anhydrous aluminum silicate and / or sodium aluminosilicate applied on the fiber is present on the surface of the fiber obtained by applying hot drawing and / or heat treatment after applying anhydrous aluminum silicate and / or sodium aluminosilicate. As the remaining amount increases, the workability in post-processing decreases as the residual amount increases, so it is necessary to remove anhydrous aluminum silicate and / or sodium aluminosilicate adhering to the fiber. There is no particular limitation on the removal method. For example, it can be removed very easily by a method of combining water application treatment and air flow injection treatment, which is already known from JP-A-63-149934.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each physical-property value in an Example was measured with the following method.

(1) Water absorption (ml / 100g)
The inorganic fine powder sample is dried at 105 ° C. for 1 hour, then allowed to cool to room temperature in a desiccator, and the weight (Wg) is measured. Next, 4-5 drops of water are dropped into the fine powder using a burette, and kneaded well with a metal spatula. The amount of dripping water (Vml) until the mixture of the inorganic fine powder and water is spirally wound or immediately softens is measured. The water absorption (O) was calculated from the following formula.
O = V / W × 100

(2) Aggregation degree (G)
A 10% by weight aqueous dispersion of an inorganic fine powder sample is prepared, and the average particle size (dμm) is measured with a particle size distribution meter. Next, the aqueous dispersion is dried at 110 ° C. for 1 hour, and the average particle size (D μm) is measured using the inorganic compound after evaporating the solvent to dryness as an aqueous dispersion of 10% by weight. The degree of aggregation (G) was calculated from the following equation.
Aggregation degree = D / d

(3) Fineness, cutting strength, cutting elongation, elastic modulus Measured according to JIS-L1013.

(4) Degree of fusion Of the total number of filaments (N) of the sample fiber, the number of filaments (n) that are not fused and can be separated one by one is counted, and the degree of fusion is determined by the following equation. This measurement is performed 5 times and an average value is taken.
Degree of fusion (%) = {(N−n) / 2N} × 100

(5) Adhesion amount of non-fusible fine powder (DPU)
About 3 g of a fiber sample not previously applied with finishing oil is sampled. Next, after drying at 120 ° C. for 1 hour, the weight A (g) is precisely weighed. Next, the sample is completely incinerated in an incinerator at 800 ° C., and the ash weight B (g) after incineration is measured and calculated by the following formula.
DPU (%) = {B / (A−B)} × 100

(6) Product quality The surface and side surface of the product wound in a cheese shape of 5 kg by a winder were visually observed and judged from the total number of fluff and loops. When the number was 5 or less, it was judged to be acceptable.

[Examples 1 to 3, Comparative Example 1]
112.9 parts of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) having a moisture content of 100 ppm or less, 1.506 parts of paraphenylenediamine and 2.789 parts of 3,4'-diaminodiphenyl ether are placed in a reaction vessel at room temperature. After dissolving in nitrogen, 5.658 parts of terephthalic acid chloride was added with stirring. The reaction was finally carried out at 85 ° C. for 60 minutes to obtain a transparent viscous polymer solution. Next, 9.174 parts of NMP slurry containing 22.5 wt% calcium hydroxide was added to carry out a neutralization reaction. The logarithmic viscosity of the obtained polymer was 3.33.

  Using the obtained polymer solution, wet spinning was carried out by extruding from a spinneret having a pore diameter of 0.3 mm and a pore number of 1000 to a coagulation bath (aqueous solution) of 30% by weight of NMP. The distance between the spinneret surface and the coagulation bath was 10 mm. The fibers spun from the spinneret are washed with water, passed through a squeeze roller to remove water adhering to the surface, and an inorganic fine powder having a composition as shown in Table 1 having a concentration of 2.0% by weight (average particles of anhydrous aluminum silicate) The film was immersed in an aqueous dispersion bath having a diameter of 1.1 μm and an average particle diameter of sodium aluminosilicate of 2.1 μm for about 1 second, and then passed through a squeeze roller to obtain a yarn to which an inorganic fine powder was adhered. Subsequently, the yarn was completely dried using a drying roller having a surface temperature of 200 ° C. and then hot-drawn 10 times at 530 ° C.

  First, water was sprayed onto the obtained drawn yarn at a shower water amount of 10 L / min to sufficiently wet the drawn yarn. Next, an air flow of 100 L / min was jetted through an air nozzle having an inner diameter of 2.0 mm and a length of 10 mm. After these operations were repeated twice, the finishing oil was applied so that the adhesion amount was 2.0% by weight, and wound up at a speed of 500 m / min. The number of filaments of the obtained fiber was 1000, and the fineness was 1670 dtex. The evaluation results are shown in Table 2.

According to the method of the present invention, first, the fiber surface is coated with an inert hydrophilic and anhydride aluminum silicate Cohesion 2.0 or less fine powder and / or sodium aluminosilicate powder aqueous dispersion of a single Since the fiber surface is coated with anhydrous aluminum silicate and / or sodium aluminosilicate and then heat-drawn and / or heat-treated at a high temperature, not only the occurrence of fusion between single fibers in this step can be suppressed, but also the drawing. After the heat treatment, the anhydrous aluminum silicate and / or sodium aluminosilicate can be easily removed by a conventionally known method. Moreover, the obtained fiber has almost no fusion between single fibers, and has good process stability in post-processing such as twisting and weaving, and there is no problem of scum generation. Furthermore, even if it is used as a reinforcing material for various matrices such as rubber, resin, etc., it also has excellent adhesiveness with the matrix, so it has the characteristics of exhibiting an excellent reinforcing effect, and is a high-quality fiber. Can be used widely.

Claims (4)

An aqueous dispersion of an inert hydrophilic inorganic fine powder of anhydrous aluminum silicate and / or sodium aluminosilicate having a cohesion degree of 2.0 or less is applied to the fiber made of a thermoplastic synthetic polymer, and then heated at a high temperature. A method for producing a thermoplastic synthetic fiber, wherein the inorganic fine powder adhering to the fiber is removed after drawing and / or heat treatment.   The method for producing a thermoplastic synthetic fiber according to claim 1, wherein the water absorption of the inorganic fine powder is 20 to 350 ml / 100 g.   The method for producing a thermoplastic synthetic fiber according to claim 1 or 2, wherein the inorganic fine powder has an average particle size of 5 µm or less.   The method for producing a thermoplastic synthetic fiber according to any one of claims 1 to 3, wherein the inorganic fine powder has a Mohs hardness of 5 or less.