JPS6332914B2 - - Google Patents

Description

[Detailed description of the invention]

a Field of Application of the Invention The present invention relates to a method for surface treatment of synthetic fibers. More specifically, the present invention relates to a surface treatment method for synthetic fibers that causes fusion between filaments during hot drawing and/or heat treatment. b. Prior Art In recent years, the demands on fibers have become more sophisticated, and in particular, various new materials have been developed and studied to meet the demands for high strength and high modulus. Among them,
Some types require high-strength stretching at high temperatures (for example, 300 to 600 degrees Celsius) or heat treatment processes at high temperatures (for example, over 250 degrees Celsius) to achieve high performance.
In this process, undesirable fusion between single yarns occurs. In other words, although some of these fibers that have fusibility during drawing (or heat treatment) exhibit high performance as a single filament, 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. No. 151944) encountered the problem that even with this method, as the number of single yarns constituting the fiber bundle increases, the effect of preventing single yarn fusion decreases. As a result of intensive research by the present inventors on the cause of this problem, we found that when an aqueous dispersion of a hydrated gel-forming inorganic compound is applied to fibers and then dried, the water content on the fibers decreases and the gel-forming inorganic compounds aggregate. As a result, the compound becomes coarse particles and adheres to the fiber surface as coarse particles, making it impossible for the compound to uniformly cover the fiber surface, and this phenomenon of uneven adhesion becomes more pronounced as the number of single fibers constituting the fiber bundle increases. I found out that it becomes c. Purpose of the Invention The purpose of the present invention is to apply an aqueous dispersion of a hydrophilic gel-forming inorganic compound to a fiber and then dry it to reduce the water content, even if the concentration of the inorganic compound becomes high. The present invention provides an industrially advantageous method in which the compound does not aggregate and can be attached to the fiber surface in the form of fine particles. d. Constitution of the Invention That is, the present invention provides a method of applying a mixture of a colloid of a hydrophilic gel-forming inorganic compound and a water-soluble compound to the surface of a fiber having fusibility during hot drawing and/or heat treatment, and then drying the mixture. This is a surface treatment method for synthetic fibers characterized by: The hydrophilic gel-forming inorganic compound used in the present invention is a compound such as hydrous aluminum silicate that forms a gel by containing 5 times or more water relative to the inorganic compound when reduced to anhydrous form, and has hydration swelling property. Examples include swellable mica, such as magnesium fluorosilicate, and colloids of hydrophilic gel-forming inorganic compounds such as colloidal silica made of finely divided silica and aluminum sol made of finely divided alumina. The water-soluble compound may be one that dissociates into cations and anions in an aqueous solution, but those that do not decompose at the heating temperature of the fibers and those whose crystals have hygroscopic or deliquescent properties are particularly preferred. The water-soluble compound used in the present invention may be either an inorganic compound or an organic compound, but in terms of high temperature stability, inorganic compounds are preferred, and NaCl ₂ , NaSO ₄ , MgSO ₄ , CaCl ₂ and the like are particularly preferred, with NaCl being preferred. Practically more preferred. In the present invention, when only a colloid of a hydrophilic gel-forming inorganic compound (hydrocolloid) is applied to the fiber and then dried, the inorganic compound coagulates during the drying process and forms secondary aggregates, as described above. Since they become coarse particles and adhere unevenly to the fiber surface, the effect of preventing fusion during hot drawing or heat treatment decreases significantly when the number of single fibers constituting the fiber bundle increases. By suppressing condensation,
The aim is to uniformly adhere the compound to the fiber surface in a finely divided state. That is, after the hydrocolloid used in the present invention is applied to the fiber surface, during the process of evaporation to dryness, as the moisture content decreases, it changes into a sol, gel, and coarse powder (amorphous). Coarse particle powder becomes secondary agglomeration, but if dehydration is attempted by weakening the hydration bonding force used for coagulation at the sol or gel stage in a water-rich state, it will not become coarse particles and will become hydrophilic. Addition of a water-soluble compound because it attaches to the yarn surface in a state similar to the basic particles when forming a colloid, and the presence of ionized ions in the colloid solution can disrupt the balance of hydration bonding force between fine particles. is valid. The effectiveness of the present invention is confirmed by microscopic observation of a hydrocolloid solution applied to a glass plate and evaporated to dryness. In other words, when only the hydrocolloid liquid is evaporated to dryness, the gel-forming inorganic compound forms coarse secondary agglomerated particles, but when an aqueous inorganic salt solution is added to the hydrocolloid liquid, no secondary agglomerated particles are formed. , kept in the state of fine particles. In particular, when the water-soluble compound forms microcrystals, when the above experiment is performed, the gel-forming inorganic compound is scattered as fine particles with the compound as a core. In the present invention, when creating a mixture of a hydrocolloid and a water-soluble compound, an aqueous solution of a water-soluble compound may be mixed with the hydrocolloid liquid, or a water-soluble compound may be added and mixed with the hydrocolloid liquid. or vice versa. In the present invention, the hydrocolloid and the water-soluble compound do not need to consist of only one component,
It goes without saying that it may be a mixture of two or more types of compounds having similar functions, and may also contain a colloidalization aid. In the present invention, the mixing ratio of the hydrophilic gel-forming inorganic compound and the water-soluble compound may be any ratio as long as the entire aqueous dispersion-aqueous solution system is stable, but preferably, the secondary aggregation of the hydrophilic gel-forming inorganic compound is It is sufficient to mix the minimum amount of water-soluble compounds that can be suppressed. In the present invention, a method of applying a mixture of a colloid of a hydrophilic gel-forming inorganic compound and a water-soluble compound to the fiber surface is preferably a method of immersing the fiber in a mixed solution while running the fiber. The amount of the inorganic compound added to the fibers is 0.05 to 15%, preferably 0.2 to 2.0%, based on the weight of the fibers, on an anhydrous basis. The fibers to which the method of the present invention can be applied include all fibers that exhibit fusibility 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 the fibers to which the method of the present invention is applied include fibers of thermoplastic polymers such as polyethylene, polypropylene, nylon, and polyester, and partially cured thermosetting resin fibers. Furthermore, examples of fibers to which the method of the present invention can be applied include the following fiber materials that have recently been developed and researched as high-strength, high-modulus fibers. For example, (1) the following repeating unit -NR ₁ -Ar ₁ -NR ₂ -CO-Ar ₂ -CO- and/or -NR ₃ -Ar ₃ -CO- (where R ₁ , R ₂ , R ₃ are It is hydrogen and/or a lower alkyl group, and Ar ₁ , Ar ₂ and Ar ₃ represent at least one aromatic residue selected from the following.

【formula】

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【formula】

【formula】

【formula】 Here, X is -O-,

[Formula] -S-,

[Formula] is shown. Further, the hydrogen atom of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ) aromatic polyamide fibers,
For example, 3,4'-diphenyl ether, 3,4'-diphenyl ether, etc., is added to a fully aromatic polyamide consisting of an aromatic residue having straight and/or parallel axes of bonds (e.g., P-phenylene, 2.6 naphthalene, 4,4'-diphenyl, etc.).
4. Stretching when formed into fibers by copolymerizing 4'-diphenyl ether, m-phenylene, etc., or by substituting some of the hydrogen atoms of aromatic residues with halogen atoms and/or lower alkyl groups. Aromatic copolyamide fiber with enhanced properties. In particular, 80 mol% or more of Ar ₁ , Ar ₂ , Ar ₃ is

[Formula] and

[Formula], the structural unit (A) is 90 to 60 mol%, and the structural unit (B) is
Aromatic copolyamide fibers that are 10-40 mol%. (2) The following structural unit group −NR ₁ −Ar ₁ −CO−NH−NH− −NR ₂ −Ar ₂ −NR ₃ − −NR ₄ −Ar ₃ −CO− −CO−Ar ₄ −CO− (here R ₁ , R ₂ , R ₃ , and R ₄ are hydrogen atoms and/or lower alkyl groups, and Ar ₁ , Ar ₂ , Ar ₃ ,
Ar ₄ represents at least one aromatic residue selected from the following.

【formula】

【formula】

【formula】

【formula】

[Formula] Further, the hydrogen atoms of the aromatic residues may be substituted with halogen atoms and/or lower alkyl groups) Fibers made of aromatic copolyamide hydrazide. For example, introducing hydrazide bonds into a fully aromatic polyamide consisting of aromatic residues with straight and/or parallel axes of bonds (e.g. (copolymerized) aromatic copolyamide hydrazide fiber. (3) The following structural unit group (Here, Ar ₁ and Ar ₂ represent at least one type of aromatic residue selected from the following.

【formula】

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【formula】

【formula】

[Formula] In addition, the hydrogen atom of the aromatic residue is a halogen atom,
It may be substituted with a lower alkyl group. ) A fiber made of an aromatic oxadiazole/methyl hydrazide copolymer. For example, the following repeating unit group

[Formula] and

An aromatic oxadiazole/methyl hydrazide copolymer fiber consisting of the formula: (4) Fibers made of thermoplastic polymers capable of forming optically anisotropic melts, such as wholly aromatic copolyesters, wholly aromatic polyazomethines, etc. etc. can be mentioned. In order to exhibit sufficient performance, the fibers (1) to (3) above require hot drawing at a high temperature that creates fusion between the fibers, and the fibers (4) require In order to obtain sufficiently high strength, heat treatment at a high temperature and for a relatively long period of time is necessary to form a fusion bond between the fibers. Furthermore, when drawing thermoplastic fibers such as polyethylene at high draw ratios (10 to 50 times) to obtain high-strength, high-modulus fibers, it is difficult to carry out drawing operations on multifilament fiber aggregates. Fusion between single yarns is unavoidable. e Effects of the Invention By applying the method of the present invention to these fibers that exhibit fusibility during hot drawing or heat treatment, or before hot drawing or heat treatment, it is possible to improve the bond between single yarns without impairing fiber performance. It is possible to prevent or significantly reduce the fusion of fibers, and it has an unprecedented advantage that a large effect can be obtained especially when the number of single yarns constituting a fiber bundle is large. f Examples The method of the present invention will be explained below with reference to Examples. The main characteristic values used in the following examples are as follows. (1) Inherent viscosity of the polymer IV (inherent viscosity) Using an Ostwald viscosity tube, the flow time of the solvent alone is to (seconds), the flow time of a dilute polymer solution is t (seconds), and the polymer concentration in the dilute solution. c
(g/de), it is expressed as IV=ln(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 (q/de). (3) Degree of fusion, 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 structural units A polymer solution prepared by dissolving 6% by weight of an aromatic copolyamide with IV = 3.1 composed of in N-methyl-2-pyrrolidone (NMP) containing CaCl ₂ was discharged at 940 g/min from a nozzle with 1000 holes with a pore size of 0.2 mm. I pushed it out at speed. After traveling about 10mm in the air,
It was coagulated in a coagulation bath of NMP/water (30/70% by weight) at 50°C, withdrawn at a speed of 30 m/min and subsequently washed in a water bath at 50°C. The washed yarn was immersed in a mixture of 1 g of NaCl in 0.5% water-dispersed colloid 10 of hydrated aluminum silicate, squeezed with a squeezing roller, and then dried on a drying roller. The amount of fine particles attached as a solid content was about 0.6% based on the weight of the dry yarn. Subsequently, it was stretched 12 times on a hot plate at 500°C, and after applying an oil agent, it was wound up.
The physical properties of the obtained yarn are shown in the table below, and the comparative example is
This is a case where only a 0.5% water-dispersed colloid of hydrated aluminum silicate without mixing NaCl was used. Comparative example of the present invention Fineness (de) 1482 1475 Strength (g/de) 25.9 25.4 Elongation (%) 4.1 4.0 Initial modulus (g/d) 620 628 Fusion degree f 1.01 1.85 Example 2 Hydrous aluminum silicate in Example 1 Instead of the water-dispersed colloid, a water-dispersed colloid of magnesium fluorosilicate, colloidal silica, and alumina sol were used.

[Table] Examples 3 to 5, Comparative Examples 3 to 5 Polymer solutions shown in the following table 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. The following table shows the drawing conditions and properties of the drawn yarn. Further, as a comparative example, a case where only a water-dispersed colloid of hydrated aluminum silicate is used is shown as a comparative example.

[Table] All of the fibers of the comparative examples lacked flexibility due to monofilament fusion. Example 6 The following structural units A fully aromatic polyester with IV = 2.1 (measured in P-chlorophenol at 50°C) was spun at a temperature of 330°C.
8.5 from a spinneret with a hole diameter of 0.5 mmφ and a number of holes of 50.
It was extruded into the air at a rate of g/min and wound up at a rate of 250 m/min. The obtained yarn was immersed in a mixture of 1 g of NaCl in 10 g of a 1% aqueous dispersion of aluminum magnesium silicate, dried, and then wound around a skein frame. 1 at 250℃ in a nitrogen stream while wrapped in a skein frame.
Heat treatment was performed for 1 hour at 260°C, 1 hour at 270°C, 1 hour at 280°C, 1 hour at 290°C, and 3 hours at 300°C. The properties of the yarn before and after heat treatment are shown below. Unheated yarn Heat treated yarn Fineness (de) 305 290 Strength (g/de) 4.1 19 Elongation (%) 1.0 4.0 Modulus (g/de) 405 395 Degree of fusion f 1.00 1.03 Comparative example 6 Implemented except that NaCl was not used When spinning and heat treatment were carried out in the same manner as in Example 6, the degree of fusion f of the obtained yarn was
2.5, which was extremely poor quality.

Claims (1)

[Claims] 1 Colloids of hydrophilic gel-forming inorganic compounds and NaCl, Na ₂ SO ₄ , MgSO ₄ , CaCl ₂ on the surface of synthetic fibers that have fusion properties during hot stretching and/or heat treatment.
1. A method for surface treatment of synthetic fibers, which comprises applying a mixture with one or more water-soluble compounds selected from the group consisting of: followed by drying.