JP2861335B2 - Method for producing naphthalate polyester fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a naphthalate polyester fiber by a direct spin drawing method.

The polyester obtained by substantially reacting naphthalene-2,6-dicarboxylic acid with ethylene glycol, that is, the fiber composed of polyethylene-2,6-naphthalate, has a higher mechanical property than the conventionally used polyethylene naltalate fiber. In addition, because of its excellent thermal properties, it has attracted attention as an industrial material fiber such as a rubber reinforcing material.

(Prior Art) Such a naphthalate polyester fiber is produced by winding a yarn obtained by melt-spinning polyethylene-2,6-naphthalate once onto a bobbin or the like and then drawing it by a pin, plate method or a heating roller method. However, when the conventional spinning process and the drawing process are directly connected to each other to produce naphthalate polyester fiber by the direct spinning and drawing method, the operability is lowered or the product quality is lowered (strength,
However, the direct spin-drawing method has never been employed when industrially producing naphthalate polyester fibers because of the problem of lowering the modulus.

Conventionally, as a method of directly spinning and drawing polyethylene naphthalate fiber, Japanese Patent Publication No. 57-2808 discloses a method of dispersing clay powder in polyethylene-2,6-naphthalate.

(Problems to be Solved by the Invention) However, the above-mentioned method of the prior art requires a step of adding and dispersing a special fine powdery inactive substance to a polymer in advance.

Further, as a method of directly spinning and drawing a conventionally used polyethylene terephthalate fiber, for example, disclosed in JP-A-52-99314, even if this method is directly applied to polyethylene naphthalate fiber, Direct drawing spinning was difficult to apply because the drawing speed had to be increased and the glass transition temperature of polyethylene naphthalate was higher than that of polyethylene terephthalate.

The present invention provides a method for producing a high-strength and high-modulus nalthalate polyester fiber by a direct spinning drawing method having industrially high productivity without using a special additive dispersed in naphthalate polyester in advance. It will not be provided.

(Means for Solving the Problems) Means for solving the above problems, that is, the present invention is to melt a naphthalate polyester having an ethylene-2,6-naphthalate unit of 90 mol% or more and an intrinsic viscosity of 0.4 or more. In producing a naphthalate polyester fiber having excellent mechanical and thermal properties by spinning and drawing, the spun yarn melted and discharged from the spinneret is cooled and solidified and taken off. A high-temperature pressurized steam jet nozzle arranged between the unstretched yarn supply roller and the first-stage stretch roller, which has been heated to 200 ° C., blows overheated steam heated to 200 ° C. or more, thereby increasing the 75% or more of the total draw ratio. A naphtalate polyester fiber characterized by performing one-stage drawing, and then performing at least the second and subsequent stages at a temperature equal to or lower than the melting point of the naphthalate polyester. It is a production method.

In the present invention, polyethylene-2,6-naphthalate means that 90 mol% or more of the polymer constituent units are ethylene-2,6-naphthalate.
-Means polyester which is a naphthalate unit. Such polyesters include polyethylene-2,6-
Naphthalate homopolymer is typical, but may be a copolymer containing an appropriate third component in a proportion of 10 mol% or less.

Suitable third components include compounds having two ester-forming functional groups, such as (a) aliphatic dicarboxylic acids, (b) alicyclic dicarboxylic acids, (c) aromatic dicarboxylic acids, (d) oxy Carboxylic acid, (e) aliphatic glycol (f) alicyclic glycol (g) aromatic diphenol, and the like. Needless to say, the polyester may contain other stabilizers such as phosphoric acid, phosphorous acid and esters thereof.

In the present invention, as the polyethylene-2,6-naltalate, the intrinsic viscosity (η) is preferably 0.4 or more and 2.0 or less,
More preferably, those having 0.55 to 1.00 are used. If the intrinsic viscosity is less than 0.4, it is difficult to obtain a fiber having sufficient mechanical and thermal properties, which is not preferable. On the other hand, those having a value of 2.0 or more have too high a melt viscosity to make melt extrusion difficult.

Next, technical features for producing the high-strength naphthalate polyester fiber of the present invention will be described.

In producing the high-strength naphthalate polyester fiber of the present invention, the polyethylene-2,6-naphthalate is melt-spun, and the spun yarn is cooled according to a conventional method. It is also useful to immediately pass the yarn through a section of high-temperature heating area and then cool it.
Then, an oil agent is applied, and immediately subjected to stretching without winding.

Next, the stretching heat treatment method of the present invention will be described. First, the drawn undrawn yarn is subjected to less than 10% pre-draft between the first roller for supplying the undrawn yarn and the second roller for supplying the undrawn yarn. If the pre-draft exceeds 10%, plastic deformation of the undrawn yarn is likely to occur, and the subsequent drawing becomes very unstable. Therefore, it is necessary to set the pre-draft of less than 10% under the condition that the running state of the yarn on the undrawn yarn supply roller can be evenly adjusted according to the number of filaments and the total fineness. In the case where no pre-draft is provided, it is difficult to maintain the uniformity of the alignment between the filaments of the undrawn yarn, and it is difficult to ensure the stability of drawing.

Pre-drafted 10 unstretched yarns
A high-temperature pressurized steam jet nozzle is provided between the undrawn yarn supplying second roller heated to 0 ° C or higher and the first-stage drawing roller, and the superheated steam heated to 200 ° C or higher is jetted to increase the total draw ratio to 75%. % Of the first-stage stretching. The temperature of the undrawn yarn supplying second roller needs to be kept within a range that does not cause the trailing of the undrawn yarn on the roller to make the running state of the undrawn yarn unstable. Therefore, the temperature of the undrawn yarn supplying second roller needs to be 100 ° C. or more and less than 150 ° C. If the undrawn yarn supplying second roller is not heated to a certain temperature, the subsequent drawing becomes unstable under the influence of the ambient temperature and the like.

A first-stage drawing is performed by installing a superheated steam jet nozzle between the heated undrawn yarn supply second roller and the first-stage drawing roller to jet superheated steam.

In particular, drawing by overheated steam is performed by supplying the undrawn yarn.
Since the crystallization of the yarn on the roller can be suppressed to a minimum, the magnification of the first-stage drawing can be increased. These techniques are unprecedented and are one of the major features of the present invention.

In this way, a highly drawn first-stage drawn yarn is obtained. The first-stage stretching ratio needs to be set so as to exceed 75% of the total stretching ratio (TDR). When the first-stage draw ratio is less than 75% of the total draw ratio, the undrawn portion remains in the first-stage drawn yarn, so that the total draw ratio cannot be increased.

The first-stretched yarn is preferably provided with a high-temperature pressurized steam jet nozzle between a first-stretch roller heated to 150 ° C. or more and a second-stretch roller heated to 200 ° C. or more, The second-stage stretching is performed by ejecting overheated steam heated to at least ° C.

In the direct spinning and drawing method of naphthalate polyester, the total draw ratio (TDR) needs to be within the range shown by the following formula.

2.21 + 3.79 × 0.923 ^x <TDR <4.04 + 6.96 × 0.923 ^x where x indicates the birefringence (Δn × 10 ³ ) of the undrawn yarn. T
If the DR exceeds the upper limit, the single fiber is cut, and it is difficult to obtain a good operating condition. If the DR is less than the lower limit, stretching becomes unstable and satisfactory physical properties cannot be obtained.

The polyethylene-2,6-naphthalate fiber having a highly elongated molecular chain as described above is subjected to a relaxation heat treatment using a heated relaxation roller following the second-stage drawing, whereby the degree of orientation of the molecular chain is increased. Can be smoothed to increase the initial modulus of the fiber and improve dimensional stability.

Polyethylene-2.6 obtained according to the present invention as described above
-Naphthalate polyester fiber has less fuzz, tensile strength 5.0-12.0 g / d, elongation 5-20%, initial modulus 200
It has a performance of up to 350 g / d and a dry heat shrinkage of 1 to 10%, which is comparable to that of a normal method in which spinning and drawing are performed independently.

Polyethylene-2,6-naphthalate polyester fiber of the present invention, various industrial materials, such as tires, belts,
It is very effective because it is useful as a reinforcing material for hoses and the like and can be manufactured at low cost.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these specific examples.
In addition, the measuring method used for evaluation of this invention is as follows.

(Intrinsic Viscosity) It was measured at 30 ° C. using a mixed solvent of p-clofphenol / tetrachloroethane = 3/1.

(Fiber strength, elongation, initial modulus) In accordance with JIS-L-1013 (1981) 7.5.1, a constant-speed elongation type tensile tester TENSILON UTM- manufactured by Toyo Baldwin Co., Ltd. Measured using III.

Examples 1 to 3 A polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.73 was cooled at a discharge rate of 190 g / min from a spinneret having a hole diameter of 0.4 mm and a number of holes of 190 maintained at 310 ° C. and cooled. It was solidified and then oiled with an oiling roller. Without winding the yarn, the yarn was immediately supplied to an undrawn yarn supply first roller rotating at a speed of 200 m / min. The yarn supplied to the unrolled yarn supply first roller was stretched under the conditions shown in Table 1.

 Table 1 shows the properties of the obtained fibers.

Example 4 Polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.95 was melt-discharged from a spinneret having a hole diameter of 0.4 mm and a number of holes of 190 maintained at 320 ° C. at a discharge rate of 95 g / min. Next, oiling was performed with an oiling roller. Without winding the yarn, the yarn was immediately supplied to an unstretched supply first roller rotating at a speed of 150 m / min. Thereafter, the film was stretched under the conditions shown in Table 1. Table 1 shows the obtained fiber properties.

Comparative Examples 1 to 4 Table 1 shows the drawing conditions and fiber properties when the drawing conditions were changed with the same undrawn yarn as in Example 1.

Comparative Example 5 Table 1 shows the drawing conditions and fiber properties when the same undrawn yarn as in Example 1 was once wound up and transferred to the drawing step.

As shown in Table 1, the polyethylene-2,6-naphthalate fiber produced by the method of the present invention has excellent mechanical properties and good dimensional stability. This is an epoch-making method that enables production at about 10 times the speed.

On the other hand, under the conditions other than the present invention shown in Comparative Examples 1 to 4, the stretchability was poor or impossible, and even if a drawn yarn was obtained, the mechanical properties were insufficient.

(Effects of the Invention) As described above, according to the present invention, a high strength and high modulus naphthalate polyester fiber can be obtained with excellent high productivity without using a special additive previously dispersed in naphthalate polyester. It can be produced by a direct spinning and drawing method.

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Claims (1)

(57) [Claims] 1. A naphthalate polyester fiber containing 90% by mole or more of ethylene-2,6-naphthalate units and having an intrinsic viscosity of 0.4 or more is melt-spun and drawn to obtain a naphthalate polyester fiber having excellent mechanical and thermal properties. Upon production, the spun yarn melt-discharged from the spinneret is cooled and solidified and taken off, and is continuously wound up without being wound up. Between the undrawn yarn supply roller heated to 100 ° C or more and the first-stage drawing roller The first-stage stretching of 75% or more of the total stretching ratio is performed by ejecting superheated steam heated to 200 ° C. or more from the high-temperature pressurized steam ejection nozzle provided, and then at least 2% at a temperature not higher than the melting point of the naphthalate polyester. A method for producing a naphthalate polyester fiber, comprising drawing at and after the first step.