JPH06104930B2 - Aromatic polyester fiber manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an aromatic polyester fiber having high strength and high elastic modulus.

(Prior Art and Problems) In recent years, it has become clear that a high-strength, high-modulus fiber can be produced by melt spinning an aromatic polyester having anisotropy when melted. This method has various advantages such as not using a solvent and using a known spinning device.

Although such fibers form highly oriented and highly crystalline fibers only by melt spinning, it is known that the heat treatment of these fibers further improves the strength and elastic modulus.

For example, Japanese Patent Publication No. 55-20008 describes a method of heat treatment in an atmosphere of an inert gas such as nitrogen gas. However, the treatment time may be long in some cases, and it has not been economically preferable to use these inert gases.

(Object of the Invention) An object of the present invention is to provide a method for producing an aromatic polyester fiber exhibiting melt anisotropy, which is characterized by heat treatment that can be economically performed at low cost.

(Means for Solving Problems) That is, according to the present invention, a fiber obtained by melt-spinning an aromatic polyester exhibiting anisotropy when melted is heated in a gas to be heat-treated, and is dehumidified as the gas. The present invention relates to a method for producing an aromatic polyester fiber, which uses an oxygen-containing gas.

What is the polyester that exhibits anisotropy when melted in the present invention?
It means that it has the property of transmitting light in the temperature range in which it can flow when the polyester sample powder is placed on the heating sample stand between two polarizing plates that are orthogonal to each other at 90 ° and the temperature is raised. .

As such an aromatic polyester, Japanese Patent Publication No. Sho 56-18016
Aromatic dicarboxylic acids, aromatic diols and / or aromatic hydroxycarboxylic acids or derivatives thereof shown in JP-A No. 55-20008 and the like, and if necessary, these and alicyclic dicarboxylic acids, alicyclic Copolymers with group diols, aliphatic diols and their derivatives are also included.

Here, as the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, 4,4′dicarboxydiphenyl, 2,6-dicarboxynaphthalene, 1,2-bis (4-carboxyphenoxy) ethane and the like, alkyls and aryls thereof, Examples thereof include nuclear substitution products of alkoxy and halogen groups.

Aromatic diols include hydroquinone, resorcin, 4,
4'-dihydroxydiphenyl, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylethane, 2,2-bis (4-hydroxyphenyl) propane, 4,4'-dihydroxy Diphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 2,6-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, etc., and their nuclear substitution products such as alkyl, aryl, alkoxy and halogen can give.

As the aromatic hydroxycarboxylic acid, p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxynaphthalene-6-carboxylic acid, 1-hydroxynaphthalene-
Examples thereof include 5-carboxylic acid and the like, and their alkyl, aryl, alkoxy, and nuclear substituents of halogen groups. Examples of the alicyclic dicarboxylic acid include trans-1,4-dicarboxycyclohexane, cis-1,4-dicarboxycyclohexane and the like, and their alkyl, aryl and halogen group-substituted products.

Examples of alicyclic and aliphatic diols include trans-1,4-dihydroxycyclohexane, cis-1,4-dihydroxycyclohexane, ethylene glycol, 1,4-butanediol and xylylenediol.

Among these combinations, preferred aromatic polyesters as the object of the present invention include (1) p-hydroxybenzoic acid residue 40 to 70 mol%, the aromatic dicarboxylic acid residue 15 to 30 mol% and aromatic Copolyester consisting of 15 to 30 mol% of diol residue, (2) Copolyester consisting of terephthalic acid and / or isophthalic acid and chlorohydroquinone, phenylhydroquinone and / or hydroquinone, (3) p-hydroxybenzoic acid residue 20 to 80 mol% and 2
Examples thereof include copolyesters comprising 20 to 80 mol% of hydroxynaphthalene-6-carboxylic acid residues.

Using these starting materials, the polyester used in the present invention can be polycondensed as it is or by esterification with an aliphatic or aromatic monocarboxylic acid or a derivative thereof, an aliphatic alcohol or a phenol or a derivative thereof, or the like. Carry out the reaction.

As the polycondensation reaction, known bulk polymerization, solution polymerization, suspension polymerization method or the like can be adopted. In some cases, at 150 to 360 ° C. under normal pressure or 10 to 0.1 torr of reduced pressure, Sb, Ti, Ge compound And the like, a stabilizer such as a phosphorus compound, a filler such as TiO ₂ , CaCO ₃ , and talc.

The obtained polymer is heat-treated as it is or in powder form in an inert gas or under reduced pressure to prepare a spinning sample. Alternatively, it can be granulated once by an extruder and used.

As the melt spinning device, a plunger having a heating control mechanism, a melting part such as a screw, a measuring part such as a gap pump,
Anything can be used as long as it has a spinning head including a spinneret.

Suitable temperature for spinning is 280-420 ° C, more preferably 300
~ 400 ℃. If the temperature is lower than 280 ° C, the load on the equipment will be large, or the sample will not be melted and homogenized sufficiently.
If the temperature is higher than 420 ℃, yarn breakage may occur due to decomposition and foaming.

As the spinneret, those generally used can be used as they are, but a preferable spinneret has a hole diameter (d) of 0.3 mm or less and a ratio of the hole length (l) to the hole diameter (l /
Examples of d) are 0.8 or more.

It is preferable to control the discharge pressure in the nozzle portion to 3 Kg / cm ² G or more, from the viewpoints of single yarn breakage and spiral discharge, acceleration of orientation, and suppression of bubbles in fibers.

The fiber obtained by the melt spinning as described above is drawn as it is or after being wound with an oil agent attached. The winding or drawing speed is usually 10 to 10,000 m / min, but 100 to 2,000 m / min is preferable from the viewpoint of productivity and stable spinning.

The thickness and cross-sectional shape of the obtained fiber are appropriately selected depending on the application, but those having a thickness of 0.5 to 10 denier are preferable in terms of physical properties.

The fibers thus obtained are heated in a gas and heat-treated.

As the gas, an oxygen-containing gas whose water is dehumidified is used.

The oxygen-containing gas has a function of giving a slight cross-link between polymer main chains by an oxidation reaction or the like to make it into a high molecular weight or decomposing and removing residual monomers and oligomers which are obstacles in exerting physical properties of the fiber after heat treatment. If the water content is high, the hydrolysis may break the molecular chain.
Strength and elastic modulus are not sufficiently improved.

The amount of water contained in the oxygen-containing gas is usually 0.3 vol% or less, preferably 0.1 vol% or less, more preferably 0.05 vol% or less. By dehumidifying, the strength and elastic modulus are improved, the lightness of the fiber is improved as compared with the conventional method, and the lightness and the saturation of the fiber are excellent as compared with the case of not dehumidifying.

Dehumidification methods for water in oxygen-containing gas include molecular sieves (molecular sieves), calcium chloride, silica gel, phosphorus pentoxide, sulfuric acid, and other adsorbents and desiccants, liquid nitrogen, liquid ammonia, LPG, etc. And a method of dehumidifying by adiabatic compression, a method of combining these, and the like.

Heating with these gases, heat treatment temperature is 200 ~ 440
C., preferably 280 to 360.degree. C., and the heat treatment time is several minutes to tens of hours.

As the gas other than oxygen in the oxygen-containing gas, nitrogen, argon, helium, or the like can be used. The oxygen concentration in the oxygen-containing gas is preferably 1 to 100 vol%.

Examples of the method of contacting the fibers obtained by melt spinning an oxygen-containing gas and an aromatic polyester exhibiting anisotropy when melted include a method in which a fiber wound into a bobbin is contacted with the gas, There is a method of continuously moving the gas in the gas flow. The tension may be applied to the extent that the fiber does not break, but it is not necessary to apply it to the extent that stretching occurs.

(Operation and Effect of the Invention) By adopting the above-mentioned technical means of the present invention, the fiber obtained by melt spinning an aromatic polyester exhibiting anisotropy during melting can be made to have higher strength and higher elasticity. .
In addition, by providing a dehumidified oxygen-containing gas atmosphere,
The effect of increasing the lightness of the fiber can be obtained as compared with the conventional heat treatment method.

The fibers thus obtained are tire cords, ropes,
It can be used for a wide range of application fields such as cables, FRP, FRTP, FRC, FRM, tension members, speaker cones, bulletproof vests, space suits, and undersea workwear.

(Examples) Examples are shown below to facilitate understanding of the present invention.
These are merely examples, and the gist of the present invention is not limited thereto. The characteristic values shown in the examples are measured and calculated as follows, and the optical anisotropy was measured by placing the sample on a heating stage and heating it at 25 ° C / min under polarized light. It was performed by visual observation.

(1) Tensile test Using Tensilon II type manufactured by Toyo Baldwin Co., Ltd., measurement was carried out at a sample interval of 20 mm and a tensile speed of 2 mm / min. The number of samples is 24, and the average value excluding the highest and lowest is shown.

(2) Fiber color tone With a colorimetric color difference meter ND-K5 manufactured by Nippon Denshoku Industries Co., Ltd., lightness L value, saturation a _L (the larger the number, the darker the red) and
b _L (the larger the number, the darker the yellow color) was measured.

The measurement sample used was a 40 mm x 40 mm x 2 mm acrylic plate in which the fibers were wound tightly.

(3) Flow temperature Using a flow tester CFT-500 manufactured by Shimadzu Corporation, diameter 1 mm,
When the temperature of an aromatic polyester sample was raised at 4 ° C / min at a pressure of 100 kg / cm ² with a nozzle having a length of 10 mm, the sample flowed through the nozzle and gave a apparent viscosity of 48000 poise as “flow temperature”. Was defined.

(Reference Example) p-acetoxybenzoic acid 7.20 Kg (40 mol), terephthalic acid 2.49 Kg (15 mol), isophthalic acid 0.83 Kg (5 mol),
4,4'-Diacetoxydiphenyl (5.45 Kg, 20.2 mol) was charged into a polymerization tank having a comb-type stirring blade, heated in a nitrogen gas atmosphere while stirring, and polymerized at 330 ° C for 3 hours. During this period, the acetic acid produced was removed, polymerization was carried out with vigorous stirring, and then gradually cooled, and the polymer was taken out of the system at 200 ° C. The polymer yield was 10.88 Kg, 97.8% of theoretical yield. This is crushed with a hammer mill from Hosokawa Micron 2.
The particles were 5 mm or less. When this was treated in a rotary kiln under a nitrogen atmosphere at 280 ° C. for 5 hours, the “flow temperature” was 326 ° C. Optical anisotropy was observed above 350 ° C.

The above polymer was melt-spun using a 30 mm extruder manufactured by Shinko Plastic Industry Co., Ltd. The spinneret has a hole diameter of 0.07 m
m, hole length 0.14 mm, and hole number 300 were used, and the spinning temperature at the spinning head was 355 ° C.

A single yarn with a winding speed of 348 m / min and a winding of 3.0 d was obtained.

(Example 1) 200 g of the fiber obtained in the reference example was wound on a bobbin having an outer diameter of 15 cm and made of aluminum and having a large number of holes having a diameter of 5 mm. Place this in a heating furnace and start at 280 ℃ for 4 hours.
The temperature was raised to 20 ° C., the mixture was treated at 320 ° C. for 3 hours, and then taken out.
The heating gas at this time is 2 m long with an internal diameter of 4 m filled with molecular sieve 4A after mixing air and nitrogen.
What was passed through a 3 cm metal tube was used. The water content in the mixed gas at 27 ° C. was 450 ppm as determined by a dew point meter (water content analyzer). Change the oxygen concentration in the mixed gas,
The strength, elastic modulus and color of the heat treated fibers are shown in Table 1.

(Comparative Example 1) Instead of the mixed gas in Example 1, 99.9 vol% nitrogen gas was used. The water content at 27 ° C was 6 ppm. The results are shown in Table 1. Compared with Example 1, the fiber elastic modulus is low and the brightness is also low.

(Comparative Example 2) Instead of the mixed gas in Example 1, air (oxygen concentration 2
1.1 vol%) was used. Air as it is (water content at 27 ° C 2.
3 vol%), silica gel filled length 25 cm, inner diameter 3 c
Heat treatment was performed using a tube having a water content of 0.88 vol% through an m tube. It can be seen that the strength and color are inferior to those of Example 1 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Kobashi 3-3-1, Kanaokahigashi-cho, Okayama-shi, Okayama Nihon Exlan Industrial Co., Ltd. (72) Seiji Takao 3-chome, Kanaokahigashi-cho, Okayama-shi, Okayama No. 1 within Nihon Exlan Industry Co., Ltd. (72) Inventor Jun Takagi 3-3-1, Kanaokahigashi-cho, Okayama City, Okayama Prefecture Within Nihon Exlan Industry Co., Ltd. (56) Reference JP-A-58-45226 (JP, A) JP-A-58-191219 (JP, A)

Claims (1)

[Claims] 1. A dehumidified oxygen-containing gas is used as a gas for heating a fiber obtained by melt-spinning an aromatic polyester exhibiting anisotropy when melted in a gas and heat-treating the fiber. Aromatic polyester fiber manufacturing method