JPH01250410A - Production of high-modulus fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing a high elastic modulus fiber made of a wholly aromatic polymer, which has high strength and high elasticity and is useful in the field of industrial materials. It provides a high rate lR fiber.

[Conventional technology]

JP-A-55-20008 describes a method of spinning polyester that can form an anisotropic melt and heat-treating it under no tension without stretching to improve its strength. JP-A No. 60-239 discloses the production of high-strength fibers by subjecting polyester of 2-naphthoic acid and p-hydroxybenzoic acid to stressless heat treatment.
This is already known in Japanese Patent No. 600 and the like.

[Problems to be solved by the present invention]

Polyester of 6-hydroxy-2-naphthoic acid and p-hydroxybenzoic acid has very good fiber forming ability, high strength and high elastic modulus, and has excellent properties such as heat resistance and chemical resistance. It is an excellent high-performance fiber with a good balance in terms of manufacturing and performance.
. However, in the fiber-reinforced planutic (FRP) field and the field where it is used as a tension member for optical fibers, etc., the initial elastic modulus is insufficient, and improvement in this point is desired. By the way, this improvement in the initial elastic modulus is
Although it is also possible by changing the polymer composition,
The desired fiber could not be obtained due to a significant decrease in spinnability and physical properties.

The object of the present invention is to find a method of significantly improving the initial elastic modulus without the above-mentioned drawbacks.

[Means to solve the problem]

That is, the present invention essentially provides a heat-treated system in which fibers obtained by melt-spinning a polymer having a proportion of 80 molti or more of repeating units of [1], [,nl] are heat-treated,
Differential scanning FAi! of the heat treatment system! Below the peak temperature of the main endothermic peak observed in L meter (DSC) measurement,
This is a method for producing a high elastic modulus fiber, which is characterized in that the final stretching is 5% or more of the elongation at break of the heat treatment system at room temperature.

More preferably, in the above-mentioned drawing method, the heat treatment system improves the strength of the spun yarn to 40% or more of the strength of the spinning yarn. A manufacturing method in which the cutting elongation at room temperature of the heat treatment system before stretching is 05 to 80≠;
Manoc is a production method characterized in that the polymer essentially consists of only the following repeating structural units ([), (II:l).

In the present invention, a polymer in which a portion essentially consisting of the following repeating structural units m and (If) is 80 mol φ or more means, for example, 20 mol φ of one or more of the following structural units as a third component. This means that it may contain the following: Alternatively, titanium oxide, kaolin, silica, barium sulfate, carbon black, pigments, etc., or antioxidants,
It may also contain an ultraviolet absorber, a light stabilizer, etc.

+0-o-σ, +0-o-o-0 It is preferable that the constituent units of the naborimer consist of only El) and (nl) from the viewpoint of melt spinnability and the strength achieved after heat treatment of the fiber. In terms of the initial elastic modulus reached after heat treatment, it may be better to include other structural units as described in JP-A-54-50594.The preferred ratio of structural units in the two-component polymer is 5 mol/min. ratio [1'l/ (Il]
If1 ranges from =10/9o to 90/1.0. From the viewpoint of melt spinnability, the preferred ratio is from 60/40 to
It is 80/20.

Further, the preferable intrinsic viscosity (ηinh) of the polymer is 3
~12dll? It is. The intrinsic viscosity referred to in the present invention is determined by the following method. The sample is dissolved in pentafluorophenol in an amount of 0.1% by weight (60-80'C) and measured with an Upperohde viscometer in a constant fWm at 60C.

When ηinh is less than 3, the % fiber forming ability is extremely poor, and the strength and initial elastic modulus of the obtained fibers are extremely low. 13
That's all for fiberization! ! : It becomes impossible to obtain fine denier fibers with f of 10 denier or less.

A higher ηinh is preferable in terms of physical properties, but from the viewpoint of operational spinning stability and fiber performance, the most preferable range is ηinh.
h is 4 to 10.

The spinning temperature is 10°C or higher than the polymer melting point (MP).
The temperature is preferably MP+80°C or lower.

The melting point of a polymer referred to in the present invention is a differential scanning calorimeter (DS).
It is determined by observing the melting transition peak appearing in C).

The shear rate t referred to in the present invention is determined by the following equation in the case of a circular nozzle.

However, r: radius of nozzle hole ((7)) Q: amount of polymer discharged per single hole (m/5ee) In the case of an irregular nozzle, the value is determined by the radius of a circle having the same hole area. At low shear rates, even if the polymer has a very high viscosity and poor fiber forming properties, when the shear rate exceeds 400 Q sec, the melt viscosity decreases and the spinnability is good), and the initial elastic modulus of the resulting fibers decreases. will improve. 100,000
When it is 5ec-1 or more, the nozzle diameter is too small and troubles such as nozzle clogging and poor cleaning occur frequently, making it impossible to use in practice. The preferred range is i o, o o O~50,
0005ec=.

The resulting fibers already have higher strength and initial elastic modulus than clothing fibers at the spinning stage, but further heat treatment can significantly improve the strength and thermal stability. . The heat treatment can be carried out in an atmosphere of an inert gas such as nitrogen or an oxygen-containing inert gas such as blown air, or in a vacuum. Preferred temperature conditions are from MP-60°C to MP
A pattern in which the temperature is gradually increased from MP-40°C or lower within the range of +20°C is more preferable. The treatment time can vary from several seconds to several hours depending on the desired performance, but the fibers used for improving the initial elastic modulus by stretching, which is the purpose of the present invention, vary depending on the constituent units of the polymer, but generally speaking It is preferable that the strength of the yarn is improved by 40% or more.

It is possible to improve the initial elastic modulus of spun yarn by stretching, but spun yarn has lower thermal stability than that of heat-treated yarns, so the effective stretching temperature range is narrow, and fluffing occurs due to the breakage of single fibers during stretching. easy. On the other hand, heat treatment systems have improved strength and thermal stability through heat treatment, so they have a wide effective stretching temperature range and are less likely to break single fibers during stretching, making stable stretching possible. A yarn with no frizz and extremely little variation in strength and initial elastic modulus can be obtained.

The heat-treated system has a final elongation at break of 5% or more of the room temperature cutting elongation of the unstretched heat-treated system at a temperature below the peak temperature ('rh) of the main endothermic peak observed in differential scanning calorimetry (IJSC) measurement. Once stretched, the initial modulus is significantly improved. A significant improvement in the initial elastic modulus as used in the present invention means an improvement of at least 50 r/d or more.

The stretching process is preferably carried out between two or more rollers, which are conventionally used for polyester fibers for clothing.

Stretching to the heat treatment system can be carried out in any number of stages, but the preferred final stretching ratio that can effectively improve the initial elastic modulus varies depending on the constituent units and composition ratio of the polymer, but is generally at room temperature of the heat treatment system. 5-200% of cutting elongation at
It is. However, the important point here is the stretching ratio in the -degree stretching.

That is, the stretching ratio between the pair of rollers constituting the first stage stretching is 5 to 80%, preferably 10 to 60%, of the cutting elongation of the heat treatment system before this one stage stretching at room temperature. That is to say. If it exceeds 80%, fluffing and thread breakage are likely to occur, and in some cases, strength may decrease. The stretching temperature is also below the peak temperature of the main endothermic peak observed when the heat treatment system before one-stage stretching is measured by DSC, and the heating methods include heating rollers, contact type hollow heaters, and non-contact type hollow heaters. Any method such as a heater may be used.

A more preferable temperature is the loss tangent t determined by dynamic viscoelasticity measurement.
The temperature ranges from above the α dispersion peak temperature (Tα) of andδ to 5° C. lower than the peak temperature Th.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these Examples. The measured values of denier, a, DE, and IM shown in the same example were obtained by measuring at room temperature a sample in which the yarn was twisted at 80 T/M.0 Example 1 Constituent unit [■] A wholly aromatic polyester polymer having a molar ratio of 70/30 and [■] was prepared. The physical properties of this polymer were ηinh = 6.0 dl/f MP = 278°C. This polymer was dried in a dryer at 140°C for 10 hours, then extruded from a single-screw pent extruder, passed through a filter consisting of a sand (stainless steel) layer and fine metal wire, and spun at 320°C. The nozzle has 300 holes with a hole diameter of 0.12 days, and a discharge amount of 167f.
/min, shear rate t = 39.000156 (! = %) Spinning speed 1000 m 7 min.

The performance of this spinning yarn is as follows: Yarn density p, (DR) = 1503 dr
Degree (DT) = l 1. (1/d elongation (DE) = 2.0% initial elasticity 4 (IM) = 590f/dTα
=91°C. This spun yarn was wound around a perforated aluminum bobbin at a winding density of 0.58 f/cc and heated at 260°C for 1 hour.

3 hours from 270℃ to 280℃, 280℃ to 285℃
Heat treatment was performed for 5 hours at ℃. The performance of the obtained heat treatment system was as follows: DR = 1481 dr DT = 25.3 r/d DE = 3.6% IM = 585 f/d Th = 331°C. After attaching 1 weight φ of an oil agent mainly composed of coconut oil to this heat treatment system, the 10th roller (R1) heated to the temperature shown in Table 1 and the 20th roller (R1) at room temperature
R2), 28% of the cutting elongation of the heat treatment system.
The film was continuously stretched at a stretching rate of 1.0%. The performance of the obtained drawn yarn was as shown in Table 1.

Margin table below 1 Example 2 Using the oil adhesion heat treatment system obtained in Example 1, R1,
Using a stretching device in which the temperature of R2 was controlled to 300° C. and room temperature, respectively, the film was continuously stretched at a stretching ratio that gave the degree of elongation (R) shown in Table 2. The performance of the obtained drawn yarn was as shown in Table 2.

Table 2 Example 3 When the A5 drawn yarn obtained in Example 1 was drawn in the same manner as in Example 2 for the purpose of two-stage drawing, it was possible to draw it to 75 inches, which is the cutting elongation of this 45 drawn yarn. 1 The performance was as shown in Table 3.

Example 4 The following configuration is C1] / [II] / [[n:l
A wholly aromatic polyester polymer with a molar ratio of = 60/20/20 was prepared.

The properties of this polymer are: η1nh=4.9 dl/? MP=298°C. This polymer was spun in the same manner as in Example 1, except that the spinning nozzle temperature was 355° C., and the obtained spun yarn was heat-treated in the same manner as in Example 1. The performance of the obtained heat treatment system is as follows: DR=1505dr DT=18. tr/d D E = 3.2% IM = 576r/d Th = = 341°C An oil agent was attached to this heat treatment in the same manner as in Example 1, and Table 4
With a device consisting of a 10th roller (R1) heated to the temperature shown in , and a 20th roller (R2) at room temperature, the heat treatment system was continuously heated at a cutting elongation of 31% (stretching ratio 1.0%). Stretched. The performance of the obtained drawn yarn was as shown in Table 4.

Table 4 Patent applicant: RiRashi Co., Ltd.

Claims (1)

[Scope of Claims] 1) A heat-treated system obtained by heat-treating fibers obtained by melt-spinning a polymer in which 80 mol% or more of the repeating units essentially consist of the following repeating units [I] and [II], Final stretching is performed at a temperature below the peak temperature of the main endothermic peak observed in differential scanning calorimetry (DSC) measurement of the heat treatment system at a cutting elongation of 5% or more of the cutting elongation at room temperature of the heat treatment system. ▲Mathematical formulas, chemical formulas, tables, etc. are available▼・・・・・・〔I
] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[II]