JPS61138715A - Production of aromatic polyester yarn - Google Patents

Abstract

PURPOSE:To make spinning stable and uniform, to promote low denier formation of fiber, and to obtain the titled yarn having high strength and high modulus of elasticity, by subjecting an aromatic polyester showing anisotropy during melting to melt spinning at a specific atmospheric temperature at the outlet of a nozzle. CONSTITUTION:The atmospheric temperature of the outlet of a spinning nozzle is controlled to a temperature range from a temperature <=100 deg.C lower than the flow temperature of an aromatic polyester showing anisotropy during melting to a temperature >= the flow temperature of the polymer, the polyester is subjected to melt spinning in the atmospheric temperature, to give the aimed yarn. The control of the atmospheric temperature of the outlet of the nozzle, for example, is carried out by attaching a cylindrical spinning column to the nozzle part, and heating the column by an infrared heater, etc. A copolymer consisting of 20-80mol% p-hydroxybenzoic acid residue and 20-80mol% 2- hydroxynaphthalene-6-carboxylic acid residue, etc. is preferably used as the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing aromatic polyester fibers 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. Since no solvent is used and the known spinning temperature is higher than that of ordinary polymers, there is a possibility that reactions such as decomposition, polymerization, and crosslinking may occur during spinning, and stable spinning for a long time such as foaming and high viscosity may occur. There were some obstacles in the way.

In addition, it is known that making fibers thinner (fine denier) is one of the means to improve the physical properties of fibers, but when melted (in the case of aromatic polyesters that exhibit this anisotropy), Unlike polymers that can be melt-spun, the solidification rate on cooling is extremely fast, making it extremely difficult to make fine denier.Therefore, for example, reducing the nozzle hole diameter may be considered, but there are problems with nozzle processing, processing costs, nozzle clogging, etc. Furthermore, when the number of nozzle holes was increased (multiple holes) to improve productivity, it became difficult to perform stable and uniform spinning due to temperature differences or temperature unevenness between the nozzle center and periphery. That was difficult.

Until now, many patent applications have been filed for aromatic polyester JiM that exhibits anisotropy during melting (such as Japanese Patent Publication No. 55-482), but most of them have been small-scale examples at the laboratory stage. Kana (This cannot be considered as knowledge from a practical perspective of stable spinning operation.

(Problems to be Solved by the Invention) An object of the present invention is to stably and uniformly spin an aromatic polyester that exhibits anisotropy when melted without problems such as single fiber breakage, and to
The object of the present invention is to provide a means for promoting fine denier, orientation, etc. during spinning, and finally producing aromatic polyester fibers with high physical properties.

(Means for Solving the Problems) The present invention provides that, when melt-spinning aromatic polyester that exhibits anisotropy when melted, the ambient air temperature at the nozzle outlet is lower than the flow temperature of the polymer and 100% lower than the flow temperature. “C
The present invention relates to a method for producing aromatic polyester fibers, which is characterized by controlling the temperature within a higher temperature range than a lower temperature.

In the present invention, polyester that exhibits anisotropy when melted is defined as 900% polyester sample powder placed on a heated sample stand between two orthogonal polarizing plates: in a temperature range where it can flow when the polyester sample powder is placed and heated. It means something that has the property of transmitting light. Examples of such aromatic polyester include Japanese Patent Publication No. 56-18016 and No. 55-20.
It consists of aromatic dicarboxylic acids, aromatic diols and/or aromatic hydroxycarboxylic acids shown in No. 008, etc., and derivatives thereof, and in some cases, these are combined with alicyclic dicarboxylic acids, alicyclic diols, and aliphatic diols. Also included are copolymers with these derivatives.

Here, the aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 4,4'-dicarboxydiphenyl, 2.
Examples include 6-dicarboxynaphthalene, 1,2-bis(4-carboxyphenoxy)ethane, and substituted substances of these 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,
Examples include 6-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, etc., and nuclear substituted products of these with alkyl, aryl, alkoxy, and halogen groups. As the aromatic hydroxycarboxylic acid, p-hydroxybenzoic acid, m-
Hydroxybenzoic acid, 2-hydroxynaphthalene-6-
Examples include carboxylic acid, 1-hydroxynaphthalene-5-carboxylic acid, etc., and nuclear substituted products of these with alkyl, aryl, alkoxy, and halogen groups. Examples of alicyclic dicarboxylic acids include trans -1+ 4-dicarboxycyclohexane, cis-1,4-dicarboxycyclohexane, and substituted products of these with alkyl, aryl, and halogen groups. As alicyclic and aliphatic diols, t
rans-1,4-dihydroxycyclohexane, c
Examples include is-1s4-dihydroxycyclohexane, ethylene glycol, 1,4-butanediol, xylylene diol, and the like.

Among these combinations, preferred aromatic polyesters for the present invention include (1) 40 to 70 mol% of p-hydroxybenzoic acid residues, 15 to 80 mol% of the above aromatic dicarboxylic acid residues, and aromatic polyesters. Diol residues 15-8
(2) copolyester consisting of terephthalic acid and/or isophthalic acid and chlorohydroquinone, phenylhydroquinone and/or hydroquinone, (3) p-hydroxybenzoic acid residue 2
Examples include copolyesters consisting of 0 to 80 mol% and 20 to 80 mol% of 2-hydroxynaphthalene-6-carboxylic acid residues. Using these starting materials, the polyesters targeted by the present invention can be obtained either as they are or as esters with aliphatic or aromatic monocarboxylic acids or derivatives thereof, aliphatic alcohols, phenols or derivatives thereof, etc. The polycondensation reaction is carried out by As the polycondensation reaction, known bulk polymerization, solution polymerization, suspension polymerization, etc. can be adopted.
Sb, Ti at 860° C. under normal pressure or reduced pressure of 10 to 0.1 torr.

A polymerization catalyst such as a Ge compound, a stabilizer such as a phosphorus compound, a filler such as Tilt, CaCO5, talc, etc. may be added as necessary.

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

Alternatively, it can also be used after being granulated once using an extruder. It is thought that the aromatic polyester used in the present invention has a molecular weight range suitable for spinning, but depending on the composition and structure, there are problems such as the lack of a solvent that can dissolve it uniformly 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. Using Shimadzu's flow tester CFT-500, diameter 1
, an aromatic polyester sample was heated at a rate of 4°C/min with a nozzle of length 10 at a pressure of 1001'/-, the sample flowed through the nozzle, and the pressure was 48.000 pois.
The "flow temperature" was defined as the temperature that gives the apparent viscosity of e.

The present inventors synthesized aromatic polyesters with various compositions and varied their flow temperatures. The temperature was found to be 280-880°C. If the flow temperature is lower than this temperature range, there are problems such as reactions during melting easily occurring and fiber elongation being difficult to obtain. This poses a problem in that it is easy to use, and the load on the device increases.

As a device for melt spinning in the present invention, a known plunger type or screw type extruder can be used. The spinning temperature is preferably 280 to 420" C1, preferably 300 to 400 °C. If the temperature is lower than this temperature range, the load on the equipment will increase or the sample melt may not be uniform. Conversely, if the temperature is lower than this temperature range Higher temperatures may cause polymer decomposition.

In the present invention, the most important point is the control of the ambient temperature from when the melt exits the nozzle until it is cooled and solidified. In the case of aromatic polyester, which exhibits anisotropy when melted, unlike polymers that can be normally melt-spun, the distance it takes to cool and solidify is extremely short. This is thought to be because the polymer molecules are highly oriented and easily crystallized, and for this reason, temperature control of the atmosphere at the nozzle exit is extremely important for stable spinning and fiber quality. The ambient temperature at the exit of the nozzle must be controlled within a temperature range lower than the flow temperature of the aromatic polyester to be melt-spun (and higher than a temperature 100°C lower than the flow temperature. In the present invention, the ambient temperature at the nozzle outlet refers to the part 5W below the nozzle surface, and it is preferable that the center and edge of the nozzle have the same temperature. It was also confirmed through experiments that the flow temperature of the fibers is almost the same.If the ambient temperature is higher than the flow temperature of aromatic polyester, there may be problems such as relaxation of orientation, or physical properties may deteriorate or yarn breakage may occur. do.

As a method for bringing the ambient temperature within the temperature range required by the present invention, for example, a cylindrical spinning tube is attached to the nozzle part,
Examples of heating methods include barrel heaters, infrared heaters, heating mediums, and the like.

Spun according to the invention. leave sin as is, or
Apply the oil, wind it up, and then pull it down.

Winding or drawing speed is 10 to 10,000 m/m
However, from the viewpoint of productivity and stable spinning, it is 10 Q ~
2.000 m/min is preferred. The thickness and cross-sectional shape of the obtained IIA pongee are selected depending on the intended use, but from the viewpoint of strength and elastic modulus, a thread diameter of 1 to 10 deniers is preferable. The obtained fibers can be used as they are, but they can be made even higher in strength and elasticity by being subjected to heat treatment, elongation, or a combination of these treatments.

(Function) By controlling the atmospheric temperature at the nozzle outlet within a specific temperature range, the aromatic polyester according to the present invention, which has an extremely fast cooling and solidifying rate unlike ordinary polymers, can be used to solve problems such as single filament breakage. It is believed that it is possible to stably and uniformly spin the fibers while reducing the denier, promoting orientation, etc., and ultimately producing aromatic polyester fibers with high physical properties.

(Effects of the Invention) As described above, the present invention provides a means for industrially producing high-strength, high-modulus fibers without operational problems from aromatic polyester polymers that exhibit anisotropy when melted. This is a noteworthy effect, and the m-fiber obtained by the present invention can be used in tire cords, lobes, cables, and FRP.

Can be used for FRTP1 speaker cones, safety clothing, tensilan members, etc.

(Examples) Examples and comparative examples are shown below to explain the present invention in detail, but these are merely illustrative and are not intended to limit the invention.

In addition, the tensile test of the fiber in the example was carried out using an Instron universal testing machine No. 1180 at a test interval of 20+w and a tensile speed of 0.5-in.

The optical anisotropy was measured by placing the sample on a heating stage, raising the temperature at 25" (7 inches) under polarized light, and observing it with the naked eye.

Reference example 1 p-acetoxybenzoic acid 7.20 to q (40 mol), terephthalic acid 2.49 to 4 (15 mol), isophthalic acid 0
．． 83 and 4 (5 mol) and 4,4'-diacetoxydiphenyl 5.45 and 4 (20.2 mol) were charged into a polymerization tank with a comb-shaped stirring blade, and the temperature was raised while stirring under a nitrogen gas atmosphere. Then, polymerization was carried out at 380°C for 8 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 the polymer was 11.00 kg, which was 98.0 kg of the theoretical yield. This was crushed with a hammer mill manufactured by Hoyoi Micron Co., Ltd.
．． The particles were 5 mm or less. When this was treated in a rotary kiln at 280 DEG C. under a nitrogen atmosphere for 5 hours, the "flow temperature" became 828 DEG C.

Optical anisotropy was observed above 850°C.

Reference Example 2 A polyester of 2°5-diacetoxydiphenyl and terephthalic acid was synthesized using the apparatus of Reference Example 1 and in the same manner. The same applies to post-processing. This polyester is 819
℃ flow temperature, and optical anisotropy was observed above 845°C.

Example 1 The polyester of Reference Example 1 was melt-spun using a screw extruder with a diameter of 80111 mm.

The nozzle used had a hole diameter of 0.12 m, a hole length of 0.2 m, and a hole of -
The number is 200. A spinning tube is attached around the nozzle, and the spinning tube is heated with a heater having a length of 100 cm. Temperature measurements were taken at two locations, and one thermocouple was attached so that it was in contact with the nozzle surface so as not to obstruct the hole in the nozzle surface, so that the temperature could be measured at the bottom five points from the nozzle surface in the center of the nozzle. The other one was at the edge of the nozzle so that it could measure 5 meters below the nozzle surface. The heating of the spinning tube was controlled by the latter thermocouple. Note that the spinning W was brought into close contact with the nozzle holder so that there were no gaps, so that the Eζ wind would not blow in during spinning. Spinning was carried out at a spinning temperature of 865°C and an ambient temperature at the nozzle outlet of 810°C.

The ambient temperature at the center of the nozzle is 811-814°C.
Met. Spinning was carried out extremely stably, and pale yellow transparent fibers were obtained. When this fiber was treated in nitrogen at 820''C for 8 hours, it had a denier of 8.21 and a strength of 29.1.
f/d, elongation was 2.9%, and Yayoi ratio was 1,010 f/d. Further, the denier dispersion was also uniform at 5.7%.

Comparative Example 1 In Example 1, the spinning tube was removed and spinning was performed under the same conditions, but single fiber breakage was observed, perhaps due to the temperature difference between the inside and outside of the nozzle, or the difference in cooling rate, and stable spinning conditions were not achieved. Yes, not at all.

Furthermore, the denier unevenness was as large as 18.9%.

Comparative Example 2 In Example 1, spinning was carried out under the same conditions except that the temperature of the air surrounding the silkworm nozzle was set to 840° C., which differed from the requirements of the present invention. Single thread breakage and contamination on the nozzle surface are noticeable.
In addition, many air bubbles were observed in the fibers, indicating that the spinning was not stable, and that the present invention was superior.

Example 2 Using the polyester of Reference Example 2, melt spinning was performed at a 60° C. in the same manner as in Example 1.

The ambient temperature at the nozzle outlet was 305°C.

Stable spinning could be performed for 1 hour, and pale yellow transparent fibers were obtained. When this fiber was treated in nitrogen for 320-08 hours, it had a denier of 4.26 and a strength of 24.9)/d.
1 elongation was 3.2%, the elastic modulus was 786 f/d, and the denier dispersion was 5.9%.

Comparative Example 3 As a comparative example of Example 2, the nozzle atmosphere temperature was set to 70"
Spinning was carried out as C. This nozzle ambient temperature is lower than the flow temperature of the aromatic polyester by 100°C or more, which is outside the requirements of the present invention.

Single yarn breakage was occasionally observed during the 1 hour period, and it could not be said that the spinning was stable.

The fiber denier dispersion was also quite poor at 10.2%, demonstrating the usefulness of the present invention.

Claims (2)

[Claims] (1) When melt-spinning an aromatic polyester that exhibits anisotropy when melted, the atmospheric temperature at the nozzle exit is controlled within a temperature range that is lower than the flow temperature of the polymer and higher than a temperature that is 100°C lower than the flow temperature. A method for producing aromatic polyester fiber, characterized by: (2) The manufacturing method according to claim 1, which uses an aromatic polyester having a flow temperature of 280 to 380°C.