JPS6047933B2 - Method for producing fibers with good defibration properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing drawn/heat-treated fibers with good defibrillation from wholly aromatic polyester.

More specifically, it relates to a method for producing fibers with good defibration properties by preventing fusion between fibers when producing high-strength/high Young's modulus fibers by hot stretching or heat-treating wholly aromatic polyester fibers at high temperatures. . B) Prior art In recent years, thermoplastic polymers with rigid molecular skeletons, such as wholly aromatic polyesters, have been made into fibers with improved heat resistance, high strength,
It is attracting attention due to the possibility of developing a high Young's modulus.

However, drawing or heat treatment of these fibers requires higher temperatures, and fusion between filaments during hot drawing or heat treatment often becomes a problem. In particular, it is already known that certain linear wholly aromatic polyesters form a melt having optical anisotropy, and that fibers obtained from the polymer melt exhibit unique physical properties.

(Unexamined Japanese Patent Publication No. 50-157619, Japanese Unexamined Patent Publication No. 50-1
58695, JP-A-51-1388).
On the other hand, it is also known that heat treatment of the fibers is effective in obtaining sufficient strength and Young's modulus. However, effective heat treatment must be performed at a temperature close to the softening point of the fiber, and fusion between single yarns during heat treatment is unavoidable. In order to prevent this, JP-A No. 1576/1986 describes that the material is pre-coated with inert inorganic fine powder such as graphite or alumina. However, it is difficult to coat fibers with these fine powders uniformly and effectively.
It's not easy. The coated fine powder also has undesirable effects such as inhibiting adhesion to rubber in applications such as rubber reinforcing fibers. C) Object of the Invention The object of the present invention is to provide a method for effectively preventing the occurrence of fusion between single filaments during hot drawing or heat treatment of wholly aromatic polyester fibers as described above.

2) Structure of the Invention The present inventors have arrived at the method of the present invention as a result of intensive research to eliminate the above-mentioned drawbacks.

That is, in the method of the present invention, when producing a fiber with high tenacity and high Young's modulus by drawing or heat-treating a fiber obtained from a wholly aromatic polyester, the fiber is pretreated with a wholly aromatic polyamide and/or a heterocyclic polyester. This is a method for producing fibers with good fibrillation properties, which comprises applying an organic solvent solution of wholly aromatic polyamide (that is, wholly aromatic polyamide-imide) and then stretching or heat-treating. As a method for attaching fully aromatic polyamides, which are non-fusible polymers, to fibers, a method in which a 0.1 to 5% by weight solution of the polymer is applied to fibers, followed by washing with water and drying is particularly effective. preferable.

According to the method of the present invention, fully aromatic polyamides, which are non-fusible polymers, can be easily applied uniformly and thinly onto fibers, and not only can sufficient anti-fusion effects be obtained, but also The fibers also have good properties in terms of adhesion to rubber.

Although the method of the present invention can be applied to various types of wholly aromatic polyester fibers, its effects are particularly remarkable in the case of fibers made of wholly aromatic polyester polymers that can form an anisotropic melt.

Here, a case that can form an anisotropic melt is a substance that brightens the field of view when observed under a polarizing microscope with the polarizing plate held at right angles at temperatures above the flow initiation temperature of the polymer. It refers to polymers, such as homo- or copolymers of fully aromatic polyesters with a loose orientation. These polymers3.
The flow temperature may be adjusted, for example, in the following manner. 1 introducing a substituent into an aromatic ring, such as a chlorine atom, a bromine atom, and a lower alkyl group, and/or
4 (introducing a different type of aromatic ring or cycloaliphatic into a part of the 2 aromatic rings to form a copolymer, and/or introducing appropriate flexibility between the 3 aromatic rings, Introducing flexibility, for example by ether linkages and/or limited length fats.

More specifically, by appropriately combining structural units represented by the general formula C, a wholly aromatic polyester polymer having a stiffness and flow temperature suitable for the purpose can be obtained.

Is this kind of polymer melt available? It can be formed into fibers using the Kanbachi Takuro method.

Examples of the non-fusible polymer to be applied to the obtained fibers include various polymers belonging to wholly aromatic polyamides and/or heterocycle-containing wholly aromatic polyamides. For example, polymers consisting of repeating units such as the following are preferred, but are not limited to the above examples.

As a method for applying the polyamide, the polyamide 0 is used.

1 to 5% by weight solution in an organic solvent, in particular N,N,N-dimethylformamide, N,N-dimethylacetamide, N-
A preferred method is to apply a solution of an organic solvent such as methyl-2-pyrrolidone or dimethyl sulfoxide, and coagulate the polyamide solution onto the fiber surface in a coagulating solution (water is preferably used). used. If the degree of retention of the polyamide is less than 0.1% by weight, a sufficient amount of adhesion cannot be obtained, and if it is more than 5% by weight, the polyamide will result in adhesion between the fibers, which is not preferable. e) Effects of the Invention As described above, fibers to which a non-fusible polymer, particularly a wholly aromatic polyamide and/or a heterocycle-containing wholly aromatic polyamide is added,
Heat treatment is carried out under stretching or heat treatment conditions suitable for improving strength, Young's modulus, and other properties without causing condensation between single filaments.

to) Example The method of the present invention will be explained below with reference to Examples.

In this example, the intrinsic viscosity of the polymer (-QinFl
) is 50 mg of polymer and 10 ml of p-chlorophenol.
The relative viscosity (77r) was determined at 50°C and calculated using the following formula. However, C is the concentration (da/dl).

Example 1 49.68 parts of p-oxybenzoic acid, 76.3 parts of diphenyl isophthalate, 26.9 parts of hydroquinone, 77.04 parts of diphenyl carbonate, and 0.0 parts of stannous acetate.
5.Pour 250-280 ml of alcohol into a polymerization pot in a nitrogen gas stream
After heating at ℃ for 60 minutes, the mixture was kept at 280 atmospheres for 3 times.

Then, the pressure inside the system was gradually reduced and the temperature was increased at the same time to 0.5Tr0rLHf at 330°C over a period of 3 minutes, and 6-powder melt polymerization was carried out under high vacuum. The intrinsic viscosity of the obtained polymer was 0.91.

When this polymer was placed on a sample stage of a polarizing microscope equipped with a heating cell and its melting state at 350°C was observed, the field of view was bright under crossed Nicol conditions, and it was found that it had optical anisotropy. The polymer obtained here was pulverized, the spinning temperature was 330°C, and the pore size was 0.37077! Yunohole 5
Extruded from a spinneret with a winding speed of 6007T
L/77!77! I wound it onto a bobbin.

The yarn obtained had the following filaments: Fineness: 34de
, strength: 5.3y/De, elongation 1.8%, initial Young's modulus: 3509/De. The thus obtained yarn was coated with 1% by weight of polymetaphenylene isophthalamide/N-methyl- After applying a 2-pyrrolidone solution and passing through a water washing bath, it was dried and wound up on an aluminum bobbin.

This was heated together with the aluminum bobbin in a nitrogen gas stream at 250°C.
Time, 260°C 1 hour, 270°C 1 hour, 280°C 1 hour
Heat treatment was carried out for 1 hour at 2906C and further for 3 hours at 3000C. Not only could the obtained yarn be easily unwound, but also almost no fusion was observed between single yarns. Furthermore, the physical properties of the single yarn in the heat treatment system were also good as shown below. Fineness 32. Seki E, strength 21.0y/De, elongation 4.7%, initial Young's modulus 400V/DeO Comparative Example 1 The untreated system obtained in Example 1 was wound onto an aluminum bobbin and subjected to the same heat treatment as in Example 1. I did it.

The resulting heat-treated system could not be undone due to fusion. Example 2 38.73 parts of terephthalic acid, 21 parts of 1,4 naphthalene dicarboxylic acid. ω part, methylhydroquinone 41.30*8
1 part, 42.67 parts of diphenyl carbonate, and 0.039 parts of stannous acetate were charged into a polymerization kettle, and polymerization was carried out under substantially the same conditions as in Example 1.

The obtained polymer had an intrinsic viscosity of 1.62, and when the melted state was observed under crossed Nicol conditions, it was found to have optical anisotropy.

The obtained polymer was pulverized, extruded through a spinneret having 5 holes with a diameter of 0.3 Tr$Lφ at a spinning temperature of 310° C., and wound onto a bobbin at a winding speed of 450 m/min.

The obtained yarn had the following single yarn physical properties. Fineness 22de
, strength 6.1f/De, elongation 2.2%, initial Young's modulus 3
80y/De The thus obtained yarn was coated with 0.05%, 0.5%, 1%, 2%,
Attach a solution of 5% of an aromatic polyamideimide polymer consisting of repeating units of the following formula in N,N-dimethylacetamide.
After passing through a water washing bath, it was dried and wound onto an aluminum bobbin.

Separately, a sample (B) was prepared which was untreated and wound onto an aluminum bobbin, and which was attached to a metal frame so that the single yarns did not come into contact with each other.

Claims (1)

[Claims] 1. When producing a fiber with high strength and high Young's modulus by hot drawing or heat treatment of a fiber made of wholly aromatic polyester,
A method for producing fibers with good defibration, which comprises applying a solution of wholly aromatic polyamide and/or heterocycle-containing wholly aromatic polyamide dissolved in an organic solvent to the fibers, and then subjecting the fibers to hot stretching or heat treatment. 2. After applying a solution of wholly aromatic polyamide and/or heterocycle-containing wholly aromatic polyamide dissolved in an organic solvent to a concentration of 0.1 to 5% by weight, the solution is washed with a coagulating liquid. The manufacturing method according to claim 1, which comprises drying. 3 As an organic solvent, N,N-dimethylformamide,
The manufacturing method according to claim 1 or 2, which uses at least one solvent selected from N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxide. 4. The manufacturing method according to claim 1, wherein the wholly aromatic polyester is capable of forming an optically anisotropic melt.