JPS62206017A - Melt spinning - Google Patents

Abstract

PURPOSE:To make stabilized spinning possible without fiber breakage, etc., promote orientation in spinning and obtain fibers having a high strength and elastic modulus, by melt spinning an aromatic polyester capable of exhibiting melt anisotropy using a specific nozzle. CONSTITUTION:An aromatic polyester capable of exhibiting anisotropy in melting is melt spun through a spinning nozzle having 7X10<-4>-4.8X10<-3>mm<2>/hole nozzle hole area to give fibers, which are then preferably wound or pulled down at 100-2,000m/min speed. A copolymer consisting of terephthalic acid and/or isophthalic acid and chlorohydroquinone, phenylhydroquinone and/or hydroquinone, etc., is preferred for the above-mentioned polyester. The diameter of the resultant fibers by spinning is preferably 10-35mum from the viewpoint of strength and elastic modulus.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for melt spinning aromatic polyester having high strength and high modulus of elasticity.

<Prior Art> In recent years, it has become clear that high-strength, high-modulus fibers can be produced by melt-spinning aromatic polyesters that exhibit anisotropy when melted. It has various advantages such as not using a solvent and being able to use known spinning equipment.

<Problems to be solved by the invention> However, these polymers have properties different from those of ordinary melt-spun polymers, such as requiring a higher spinning temperature than ordinary polymers and having a large temperature dependence of melt viscosity. have.

Previous reports on aromatic polyesters exhibiting anisotropy when melted (Japanese Patent Publication No. 55-482, etc.) were only at the laboratory stage, and could not provide knowledge of stable spinning operations on an industrial scale.

The purpose of the present invention is to be able to stably spin an aromatic polyester that exhibits anisotropy when melted without problems such as single fiber breakage, promote orientation during spinning, and ultimately produce fibers with improved physical properties. The object of the present invention is to provide a melt spinning method that can obtain the desired results.

Means for Solving the Problems> An object of the present invention is to provide a method for spinning aromatic polyester that exhibits anisotropy when melted, in which the area of the nozzle hole is 7.5 mm. OX
This can be achieved by using a spinning nozzle that is 10-4 to 4.8 x 10-'mm''/hole.

In the present invention, the polyester that exhibits anisotropy when melted means that when the polyester sample powder is placed on a heated sample stage between two polarizing plates that are perpendicular to each other at 90° and the temperature is raised, in the temperature range where it can flow. It means something that has the property of being able to transmit light.

Such aromatic polyester is
Consisting of aromatic dicarboxylic acids, aromatic diols and/or aromatic hydroxycarboxylic acids and derivatives thereof as shown in Publication No. 6 and Publication No. 55-200'08, etc.
In some cases, copolymers of these with alicyclic dicarboxylic acids, alicyclic diols, aliphatic diols, and derivatives thereof are also included.

Here, the aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 4.4°-dicarboxydiphenyl, 2.
Examples thereof include 6-dicarboxynaphthalene, 1,2-bis(4-carboxyphenoxy)ethane, etc., and nuclear-substituted products of these with alkyl, aryl, alkoxy, and halogen groups.

Aromatic diols include hydroquinone, resorcinol, 4
．． 4°-dihydroxydiphenyl, 4.4°-dihydroxybenzophenone, 4.4°-dihydroxydiphenylmethane, 4.4°-dihydroxydiphenylethane, 2.2-bis(4-hydroxyphenyl)propane, 4. 4'-dihydroxydiphenyl ether, 4.4'-dihydroxydiphenyl sulfone, 4'4'-dihydroxydiphenyl sulfide, 2'6-dihydroxynaphthalene, 5-dihydroxynaphthalene, etc. and their alkyl, aryl, alkoxy, and halogen groups Examples include nuclear substitution products.

Aromatic hydroxycarboxylic acids include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxynaphthalene-6-carboxylic acid, 1-hydroxynaphthalene-5-carboxylic acid, and their alkyl, aryl, alkoxy, and halogen groups. Examples include nuclear substitution products.

As an alicyclic dicarboxylic acid, trans 1+
Examples include 4-dicarpoxycyclohexane, cis-1,4-dicarboxycyclohexane, and their alkyl, aryl, and halogen group-substituted products.

As alicyclic and aliphatic diols, trans -1
,4-dihydroxycyclohexane, cis-1,4-
Dihydroxycyclohexane, ethylene glycol, 1
, 4-butanediol, xylylene diol and the like.

Among these combinations, preferable aromatic polyesters for the present invention include ill p-hydroxybenzoic acid residues of 40 to 70 mol%, the above-mentioned aromatic dicarboxylic acid residues of 15 to 30 mol%, and aromatic diol residues. Group 15~
Copolyester consisting of 30 mol%, (2) Copolyester consisting of terephthalic acid and/or isophthalic acid and chlorhydroginone, phenylhydroquinone and/or hydroquinone, (3) 20 to 80 mol% of p-hydroxybenzoic acid residues. and a 2-hydroxynaphthalene-6-carboxylic acid residue i of 20 to 80 mol %.

Using these starting materials, aromatic polyesters used in the present invention can be obtained either as they are or by esterification with aliphatic or aromatic monocarboxylic acids or their derivatives, aliphatic alcohols, phenols, or their derivatives. Perform a condensation reaction.

As the polycondensation reaction, known bulk polymerization, solution polymerization, suspension polymerization, etc. can be adopted, and depending on the case, 150 to 36
Sb at 0°C under normal pressure or reduced pressure of 10 to O, Itorr,
This can be carried out by adding a polymerization catalyst such as a Ti or Ge compound, a stabilizer such as a phosphorus compound, or a filler such as T i OH, Ca COz, or talc.

The obtained polymer is used as it is or as a powder by heat treatment in an inert gas or under reduced pressure to prepare a sample for spinning.

Alternatively, it can be used after being granulated once using an extruder.

Although it is thought that the aromatic polyester used in the present invention has a molecular weight range suitable for spinning, there are problems such as the lack of a solvent that can uniformly dissolve some compositions and structures, and the lack of precision in the molecular weight measurement method. It cannot be used as a standard for aromatic polyester suitable for invention.

Therefore, the present inventors introduced "flow temperature" as a physical property value corresponding to the molecular weight suitable for melt spinning conditions.

That is, using a flow tester CFT-500 made by Shimabara Seisakusho, a nozzle with a diameter of 1 mm and a length of 10 m, the pressure was 100 kg/
cm, the aromatic polyester sample was heated at 4°C/min, the sample flowed through the nozzle, and
The "flow temperature" was defined as the temperature that gives the appearance of poise viscosity.

The present inventors synthesized aromatic polyesters with various compositions and varied their flow temperatures. was found to be 280-380°C.

If the flow temperature is lower than this temperature range, there are problems such as reactions during melting and poor fiber elongation. This poses a problem in that it is easy to occur and the load on the device becomes large.

As the apparatus used for melt spinning in the present invention, a known plunger type or screw type extruder can be used. The latter is superior in terms of continuous spinning. Known auxiliary equipment such as a gear pump can also be used.

The temperature suitable for melt spinning is usually about 300-400°C. If the temperature is below this range, the load on the apparatus will be large and the melting of the sample will become insufficiently uniform. At temperatures exceeding this range, single filament breakage may occur due to foaming or crosslinking due to decomposition or the like.

The feature of the present invention is that when spinning aromatic polyester that exhibits anisotropy when melted, the area of the nozzle hole is 7.0
The aim is to use a spinning nozzle with a diameter of 10-4 to 4.8 X IQ-3 mm"/hole.

The area of the nozzle hole is 7.0XIO-' ~ 4.8xlQ-
By using a spinning nozzle with a diameter of 'mm'/hole, there are fewer single fiber breakages, and the formation of a laminar flow allows molecules to be extremely easily oriented in the discharge direction (nozzle length direction) (and the relaxation of molecular alignment is suppressed). As a result, fibers with extremely large molecular orientation within the fibers can be obtained.

If the area of the nozzle hole is larger than this range, molecular orientation is often insufficient, whereas if it is smaller, problems such as single yarn breakage, difficulty in processing, and associated increase in processing costs will occur. .

The cross-sectional shape at the nozzle exit can be selected depending on the use of the fiber, but it may be any shape as long as it satisfies the above requirements. The nozzle taper can be appropriately selected depending on spinning conditions and polymer properties.

The fibers spun according to the present invention can be rolled up as they are, or coated with an oil and then rolled up.

Winding or drawing speed is 10 to 10,000 m/min
However, from the viewpoint of productivity and stable spinning, it is 100 to 2000
m/min is preferred.

The thickness and cross-sectional shape of the resulting fibers are selected depending on the intended use, but from the viewpoint of strength and elastic modulus, a thread diameter of 10 to 358 m is preferable.

The obtained fibers can be used as they are, but they can be further increased in strength and modulus by being subjected to heat treatment, stretching, or a combination of these treatments.

<Effects of the Invention> By using the method of the present invention, aromatic polyester that exhibits anisotropy when melted can be melt-spun without operational problems, and high-strength, high-modulus fibers with accelerated orientation can be produced with industrial advantage. can be manufactured.

The fibers obtained according to the present invention can be used for tire cords, ropes, cables, FRP, FRTP, speaker cones, safety clothing, tension members, etc.

<Example> Below, the tensile test of fibers was performed using Instron Universal Testing Machine No.
, 1130, sample interval 20tm, tensile speed 0.5
Measured at Tsuru/min.

The optical anisotropy was measured by placing the sample on a heating stage, raising the temperature at 25° C./min under polarized light, and observing it with the naked eye.

Reference example 1 p-7 setoxybenzoic acid 7.20 kg (40 mol), 2
．． 6-dicarpoxynaphthalene 4.36 +r (20 mol), 4.4°-diacetoxydiphenyl 5.45k
g (20.2 mol) was charged into a polymerization tank with a rectangular stirring blade, heated while stirring in a nitrogen gas atmosphere, and heated to 330
Polymerization was carried out at ℃ for 3 hours.

During this time, the acetic acid produced was removed and polymerization was carried out with strong stirring, after which it was gradually cooled and the polymer was taken out of the system at 200°C.

The yield of polymer was 11.89 kg, 97.8% of the theoretical yield.
Met.

This was crushed with a hammer mill manufactured by Hosyo Micron Co., Ltd., and 2.5
The particles were 1- or less. When this was treated in a rotary kiln at 280°C under a nitrogen atmosphere for 5 hours, the "flow temperature" was 326°C, and optical anisotropy was observed above 350°C.

Example 1 Using the polyester of Reference Example 1, melt spinning was performed at 365° C. using a screw extruder with a diameter of 30 mm.

The nozzle used had a discharge hole diameter of 0.065 mm (nozzle hole area: 3.33 x 10-'mm''/hole) and a nozzle pore length of 0.14 mm.

Spinning was carried out smoothly with few single fiber breakages, and even after about 4 hours, there was very little dirt on the nozzle surface and there was no effect on spinning.

Even if the discharge pressure was varied, the spinning stability did not change.

When the obtained transparent golden fiber was heat-treated in nitrogen at 320°C for 3 hours, the fiber diameter was 17.2 μm and the strength was 28.8 g.
/d, elongation 2.7%, and elastic modulus 1080 g/d.

Example 2 Discharge hole diameter 0.05 mm (nozzle hole area 1.96
Spinning was carried out in the same manner as in Example 1, except that a nozzle with a diameter of 10 mm"/hole) and a hole length of 0.07 mm was used.

The spinning was stable even after 3 hours, there were few single fiber breakages, and there was very little dirt on the nozzle surface.

Even if the discharge pressure was varied, the spinning stability did not change.

When the obtained fibers were heat-treated at 320°C for 3 hours in nitrogen, the fiber diameter was 15.8 μm and the strength was 27°6 g/d.
, elongation was 2.6%, and elastic modulus was 1130 g/d.

Comparative Example 1 Discharge hole diameter: 0.12 mm, nozzle hole length: 0.24 mm, nozzle hole area: 1. Melt spinning was carried out as in Example 1 except that a 13 x 10-"mm"/hole nozzle was used.

Spinning was stable at first, but after about 3 hours, single yarn breakage started to occur occasionally due to dirt on the nozzle surface.
Compared to No. 2, it was inferior in continuous spinning properties.

Also, thread breakage was observed when the discharge pressure was varied.

When the obtained fibers were heat-treated under the same conditions as in Example 1.2, the fiber diameter was 18.6 μm, the strength was 18.0 g/d, and the elongation was 2.
．． 1%, and the elastic modulus was 886 g/d.

Comparative Example 2 Discharge hole diameter is 8 μm (nozzle hole area 5.OXIO-Sm
Melt spinning was performed in the same manner as in Example 1, except that a nozzle of mz/hole) was used.

Spinning was extremely unstable, the nozzle clogged, and there were many thread breakages, making it impossible to obtain fiber.

Claims (1)

[Claims] When melt-spinning aromatic polyester that exhibits anisotropy when melted, the area of the nozzle hole is 7.0 x 10^-^4~4
．． A melt spinning method characterized in that a spinning nozzle with a diameter of 8×10^-^3 mm^2/hole is used.