JPS6328133B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for surface modification of synthetic fibers. More specifically, the present invention relates to a method of preventing fusion by modifying the surface of synthetic fibers that cause fusion between filaments during hot drawing and/or heat treatment. Prior Art In recent years, the demands on fibers have become more sophisticated, and in particular, various new materials are being developed and studied in response to the demands for high strength and high modulus. For some of them, high-magnification stretching at high temperatures or a heat treatment process at high temperatures is applied to achieve high performance, and undesirable fusion between single filaments occurs during this process. In other words, although some of these fibers that have fusibility during drawing (or heat treatment) exhibit high performance as single filaments, when a multifilament fiber bundle is drawn and/or heat treated in the usual manner, In many cases, the fusion between single yarns is significant, and the performance as an aggregate is significantly impaired. As a method for preventing the above-mentioned single filament fusion, the present inventors previously proposed a method of applying a hydrated gel-forming inorganic compound to the surface of the fiber during hot drawing and/or heat treatment (Japanese Patent Application No. 1983). −151944). However, even with this method, a problem has been encountered in that as the number of single yarns constituting the fiber bundle increases, the effect of preventing single yarn fusion decreases. Regarding the cause,
As a result of extensive research by the present inventors, we found that when an aqueous dispersion of a hydrated gel-forming inorganic compound is applied to fibers and dried, the water content on the fibers decreases and the gel-forming inorganic compounds aggregate to form coarse particles. As a result, the compound becomes unable to cover the fiber surface uniformly, and this phenomenon of non-uniform adhesion becomes more pronounced as the number of single fibers constituting the fiber bundle increases. I found out. Purpose of the Invention Based on the above-mentioned knowledge, the present inventors applied an aqueous dispersion of a hydrophilic gel-forming inorganic compound to fibers and then dried the fibers to reduce the water content. Even at high temperatures, the compound does not aggregate and can adhere to the fiber surface in the form of fine particles.
The present invention was achieved as a result of intensive research aimed at providing a method that can effectively prevent fusion between single yarns even when the number of single yarns is large. Structure of the Invention That is, the present invention provides a method of applying a mixture of a hydrophilic gel-forming inorganic compound colloid and a hydrophobic colloid to the surface of a fiber having fusibility during hot drawing and/or heat treatment, and then drying the mixture. This method is characterized by Here, the hydrophilic gel-forming inorganic compound refers to a compound such as hydrophilic aluminum silicate that forms a gel by containing 5 times or more water relative to the inorganic compound when reduced to anhydrous form, and a swellable compound that has hydration swelling property. Micas, such as magnesium fluorosilicate,
Furthermore, examples of colloids of hydrophilic gel-forming inorganic compounds include colloidal silica made of finely divided silica and alumina sol made of finely divided alumina. Furthermore, hydrophobic colloid is an aqueous dispersion system of finely divided inorganic particles that have a weak affinity for water, such as colloidal graphite. When only a colloid of a hydrophilic gel-forming inorganic compound (hydrocolloid) is applied to a fiber and then dried, the inorganic compound coagulates during the drying process and becomes coarse particles of secondary aggregates, as described above. Since the hydrophobic colloid adheres unevenly to the fiber surface, there is a problem that as the number of single fibers constituting the fiber bundle increases, the effect of preventing fusion during hot drawing or heat treatment decreases significantly. Since there is a problem that inorganic fine particles cannot be uniformly attached to the fiber surface, in the present invention, in order to suppress the coagulation of the hydrophilic gel-forming inorganic compound and to uniformly attach the compound in the form of fine particles to the fiber surface. , a hydrophilic colloid and a hydrophobic colloid are mixed, and the hydrophilic colloid protects the constituent fine particles of the hydrophobic colloid, stabilizing the hydrophobic colloid, and at the same time reducing the charge used by the hydrophilic colloid for coagulation. In the present invention, when mixing a hydrophilic colloid and a hydrophobic colloid, each aqueous colloid may be prepared and then mixed, or a hydrophilic gel-forming inorganic compound may be dispersed in the hydrophobic colloid. Fine particles constituting the hydrophobic colloid may be dispersed in the hydrophilic colloid. Further, the hydrophilic colloid and the hydrophobic colloid do not need to be composed of only one component of each compound, but may be a mixture of two or more kinds of compounds having similar functions. Moreover, a colloidalization aid may be included if necessary. In the present invention, the mixing ratio of hydrophilic colloid and hydrophobic colloid may be any ratio as long as the entire mixed system is stable, but it is preferable that the hydrophilic gel-forming inorganic compound envelops the constituent fine particles of the hydrophobic colloid. The ratio, specifically the ratio of the respective constituent active ingredients, is preferably in the range of 10:1 to 10,000:1. In the present invention, the method for applying a mixture of hydrophilic colloid and hydrophobic colloid to the fiber surface is as follows:
A method of immersing the fibers in the mixed solution while running them is preferred. The amount of the inorganic compound added to the fiber is 0.05 to 5% by weight, preferably 0.2 to 2.0% by weight, based on the weight of the fiber. The synthetic fibers to which the method of the present invention can be applied include all those that exhibit fusion properties during hot drawing and/or heat treatment. Here, fusion property refers to the property of forming a fused portion between fibers when a plurality of fibers are heat-stretched and/or heat-treated as a fiber bundle.
Examples of fibers to which the method of the present invention can be applied include fibers of thermoplastic polymers such as polyethylene, polypropylene, nylon, and polyester, and partially cured thermosetting resin fibers. Further, as fibers to which the method of the present invention is applied, synthetic fiber materials made of the following polymers, which have been developed and researched as high strength and high modulus fibers in recent years, are suitable. (a) The following repeating units, −NR ₁ −Ar ₁ −NR ₂ −CO−Ar ₂ −CO− and/or −NR ₃ −Ar ₃ −CO− [where R ₁ , R ₂ , and R ₃ are hydrogen They are atoms and/or lower alkyl groups, and Ar ₁ , Ar ₂ , and Ar ₃ represent aromatic residues selected from the following.

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【formula】

[Formula] Here, X represents -O-, -CO-, -S-, -SO ₂ -. Further, some of the hydrogen atoms of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ] An aromatic copolyamide composed of. Such aromatic copolyamides include, for example, fully aromatic polyamides consisting of aromatic residues (p-phenylene, 2,6 naphthalene, 4,4'-diphenyl, etc.) having straight and/or parallel axial bonds. In addition, 3,4'-diphenyl ether, 4,4'-diphenyl ether, m-phenylene, etc. are copolymerized, and some of the hydrogen atoms of aromatic residues are replaced with halogen atoms and/or lower alkyl groups. Examples include aromatic copolyamides that have improved drawability when formed into fibers by substituting with Ar ₁ , Ar ₂ , and Ar ₃ .
80 mol% or more

[expression] or

[Formula] An aromatic copolyamide in which the mole % of the structural unit (B) is 10 to 40, and in which R ₁ , R ₂ , and R ₃ are all hydrogen atoms is preferable. (b) The following four repeating units −NR ₂ −Ar ₁ −CO−NH−NH− (C) −NR ₂ −Ar ₂ −NR ₃ − (D) −NR ₂ −Ar ₃ −CO− (E) − CO-Ar ₄ -CO- (F) [Here, R ₁ , R ₂ , R ₃ are hydrogen atoms and/or lower alkyl groups, Ar ₁ , Ar ₂ , Ar ₃ ,
Ar ₄ represents an aromatic residue selected from the following.

【formula】

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[Formula] Furthermore, some of the hydrogen atoms of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ] An aromatic copolyamide hydrazide consisting of. Such aromatic copolyamide hydrazides include, for example, the introduction of hydrazide bonds into a fully aromatic polyamide consisting of aromatic residues having straight and/or parallel axial bonding hands (e.g. Examples include aromatic copolyamide hydrazides prepared by copolymerizing Ar ₁ , Ar ₂ , Ar ₃ ,
Preferably, 80 mol% or more of Ar ₄ is a p-phenylenic acid group, and R ₁ , R ₂ , R ₃ , and R ₄ are all hydrogen atoms. (c) The following repeating unit An aromatic oxadiazole/methyl hydrazide copolymer consisting of [where Ar ₁ and Ar ₂ are the same as in (b) above]. (d) Thermoplastic polymers capable of forming optically anisotropic melts, such as fully aromatic polyesters, aromatic polyazomethines, etc. Effects of the Invention In order for fibers made of the polymers (a) to (c) above to exhibit sufficient performance, it is necessary to heat them at a high temperature (for example, a temperature of 300°C or higher) that causes fusion between the fibers. Stretching is necessary, and in order to obtain sufficiently high strength in the fibers of (d), heat treatment at a high temperature and for a relatively long period of time is necessary to form fusion between the fibers. In addition, by stretching thermoplastic fibers such as polyethylene at a high stretching ratio (10 to 50 times),
Even in the case of obtaining high-strength, high-modulus fibers, when attempting to carry out a drawing operation on a multifilament fiber aggregate, fusion between single filaments is unavoidable. By applying the method of the present invention to these fibers that exhibit fusion properties during hot drawing and/or heat treatment, it is possible to prevent or significantly reduce fusion between single yarns without impairing fiber performance. becomes possible,
Particularly, a great effect can be obtained when the number of single yarns constituting the fiber bundle is large. Such effects will become clearer from the experimental results shown in the following Examples and Comparative Examples. EXAMPLES The method of the present invention will be explained below by way of examples. The main characteristic values used in the following examples are as follows. (1) Inherent viscosity of the polymer
Using an Ostwald type viscosity tube, if the flow time of only the solvent is to (seconds), the flow time of a dilute polymer solution is t (seconds), and the polymer concentration in the dilute solution is (g/de), then IV = ln It is expressed as (t/to)/C(de/g). Unless otherwise specified, solvents are
Measure at 30°C using 97.5% sulfuric acid, C = 0.5g/de. (2) Tensile properties of fibers Initial length 25 cm,
The stretching curve is measured at a tensile speed of 10 cm/min in an atmosphere of 20°C and 65% RH. From this, strength (g/de), elongation (%), and Young's modulus (g/de) are calculated. (3) Fusing degree f The value obtained by dividing the number of single filaments that should originally exist in the yarn by the number of filaments actually counted in the yarn after drawing or heat treatment is used. That is, it shows how many single filaments on average are fused together to form one filament after drawing or heat treatment. Measurements were taken at five locations, and the average value was taken as f. Example 1 The following monomer units A polymer solution prepared by melting 6% by weight of an aromatic _copolyamide with IV=3.1 composed of It was extruded at the discharge speed. After traveling approximately 10 mm in the air, the N-methyl-pyrrolidone/water (30/70
% by weight) in a coagulation bath, withdrawn at a speed of 30 m/min and subsequently washed in a water bath at 50°C.
Water-washed yarn is colloidal graphite (graphite content 22%) in 0.5% water-dispersed colloid of hydrated aluminum silicate.
were immersed in a liquid mixed at a ratio of 2 c.c., squeezed with a squeezing roller, and then wound around a drying roller and dried. The amount of fine particles attached as a solid content was about 0.6% based on the weight of the dry yarn. Subsequently, the film was stretched 12 times on a hot plate at 500°C, coated with an oil agent, and then wound. The physical properties of the obtained yarn are shown in Table 1, and the comparative example is a case where only a 0.5% water-dispersed colloid of hydrated aluminum silicate without mixing colloidal graphite was used.

[Table] Example 2 In Example 1, instead of the water-dispersed colloid of hydrous aluminum silicate, a water-dispersed colloid of fluorinated magnesium silicate, colloidal silica, and alumina sol were used. The results are shown in Table 2.

[Table] In Table 2 above, ( ) indicates the degree of fusion when colloidal graphite is not mixed and used. Examples 3 to 5, Comparative Examples 3 to 5 The polymer solutions shown in Table 3 were spun and stretched according to Example 1. However, in each example, the discharge amount was adjusted to match the final denier.

[Table] The amount of fine particles attached as a solid content was about 0.5% based on the weight of the dry yarn. Table 4 below shows the drawing conditions and properties of the drawn yarn. Further, for the purpose of comparison, a case where only a hydrated aluminum silicate water-dispersed colloid is used is shown as a comparative example.

[Table] The fibers of the comparative examples were all fused at single filament intervals.
It lacked flexibility. Example 6 The following structural units IV = 2.1 (50°C in p-chlorophenol)
Spinning a fully aromatic polyester (measured at a temperature of 330
From a spinneret with a pore diameter of 0.5 mmφ and 50 holes at ℃
It was extruded into air at 8.5 g/mm and wound up at 250 m/min. The obtained yarn was immersed in a mixture of 2 c.c. of colloidal graphite (graphite content 22%) in 1% aqueous dispersion of magnesium aluminum silicate, dried, and then wound around a skein frame. Ivy. While wrapped in a skein frame, heat at 250℃ for 1 hour in a nitrogen stream, then at 260℃ for 1 hour.
270℃ for 1 hour, 280℃ for 1 hour, 290℃ for 1 hour,
Heat treatment was performed at 300°C for 3 hours. The properties of the yarn before and after heat treatment are shown in Table 5 below.

[Table] Comparative Example 6 When spinning and heat treatment were carried out in the same manner as in Example 6 except that colloidal graphite was not mixed and used, the obtained yarn had a degree of fusion f of 2.5 and was of extremely poor quality.

Claims (1)

[Scope of Claims] 1. A synthetic fiber characterized in that a mixture of a colloid of a silicate compound and colloidal graphite is applied to the surface of a synthetic fiber having fusibility during hot drawing and/or heat treatment, and then drying. Surface modification method. 2 Synthetic fibers contain the following repeating units -NR ₁ -Ar ₁ -NR ₂ -CO-Ar ₂ -CO- and/or -NR ₃ -Ar ₃ -CO- [where R ₁ , R ₂ , and R ₃ are hydrogen] They are atoms and/or lower alkyl groups, and Ar ₁ , Ar ₂ , and Ar ₃ represent aromatic residues selected from the following.
[Formula] [Formula] [Formula] [Formula] [Formula] [Formula] [Formula] Here, X represents -O-, [Formula] -S-, [Formula]. Further, the hydrogen atom of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ] A method for surface modification of a synthetic fiber according to claim 1, which is an aromatic copolyamide fiber consisting of: 3 80 mol% or more of Ar ₁ , Ar ₂ , Ar ₃ is the following aromatic residue [The hydrogen atoms of these aromatic residues may be substituted with a halogen atom and/or a lower alkyl group. ] The method for surface modification of synthetic fibers according to claim 1 or 2, wherein the amount of the structural unit (B) is 10 to 40 mol%. 4. The method for surface modification of synthetic fibers according to any one of claims 1 to 3, wherein R ₁ , R ₂ , and R ₃ are all hydrogen atoms. 5. The method for surface modification of synthetic fibers according to claim 1, wherein the thermoplastic polymer is a wholly aromatic polyester. 6. The method for surface modification of synthetic fibers according to claim 1, wherein the thermoplastic polymer is aromatic polyazomethine.