JP2823787B2 - Method for producing high molecular weight polyester fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester fiber having excellent mechanical properties by spinning a high molecular weight polyester by a wet or semi-dry semi-wet method.

[0002]

2. Description of the Related Art Polyester fibers, especially polyethylene terephthalate fibers, are widely used not only for clothing but also for industrial use because of their well-balanced physical properties and good spinning and drawing properties. In particular, high-strength polyester fibers are useful for various industrial materials such as tires.

For the polyester fiber, a melt spinning method, which is usually economically advantageous, is employed. In order to develop the high strength required for industrial use, the polyester fiber is melt-spun using a polyester having a high degree of polymerization. Then, it is general to perform stretching at a high magnification. However, there is an upper limit to the melt viscosity of a polymer to which melt spinning can be applied, and with a polyester having an intrinsic viscosity of 1.2 or more, it is difficult to obtain a substantially stretchable raw yarn in the spinning step. As a result, strength 1 in melt spinning
It has been difficult to industrially produce fibers exceeding 0 g / d.

On the other hand, a method of dissolving a polyester in an organic solvent and spinning the same to make a polyester having a higher polymerization degree into a fiber is disclosed in JP-A-61-2.
No. 07616, JP-A-62-30024 and JP-A-4-73212. However, JP
The methods disclosed in JP-A-207616 and JP-A-4-73212 use dichloroacetic acid and hexafluoroisopropanol as solvents, respectively. All of them have a problem in industrial practical use because a large amount of an extremely expensive solvent is used. Also, Japanese Patent Application Laid-Open No. 62-30024
Method No. uses nitrobenzene as a solvent, but it is necessary to heat the polymer to 200 ° C. or higher to dissolve the polymer.
It is difficult to avoid a decrease in the degree of polymerization during dissolution.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to convert a high molecular weight polyester into a fiber by a practical wet or semi-dry semi-wet process to obtain a strength of 10 g which cannot be obtained by conventional melt spinning. An object of the present invention is to provide a method for producing a polyester fiber excellent in mechanical properties exceeding / d.

[0006]

According to the present invention , the intrinsic viscosity is as follows:
A polyester consisting essentially of at least 1.2 ethylene terephthalate units is converted to p-chlorophenol or p-chlorophenol.
It is dissolved in a mixed solvent of chlorophenol and another chlorinated solvent, and is subjected to wet or semi-dry semi-wet spinning using a coagulation bath mainly composed of ethylene glycol. A method for producing a high molecular weight polyester fiber.

The polyester to be used in the present invention is substantially composed of ethylene terephthalate units, and has terephthalic acid as a main acid component and ethylene glycol as a main glycol component. Here, “main” means that the content exceeds 60 mol%, preferably 80 mol%. Accordingly, less than 40 mol%, preferably less than 20 mol%, of other acid components and other diol components (third components) may be contained.

The third component copolymerizable with the polyester as a starting material in the method of the present invention includes aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, oxalic acid, malonic acid, and the like. Succinic acid, adipic acid,
Sebacic acid, aliphatic dicarboxylic acids such as decane dicarboxylic acid, hexahydroterephthalic acid, decalin dicarboxylic acid, alicyclic dicarboxylic acids such as tetralin dicarboxylic acid,
Oxyacids such as glycolic acid and p-hydroxybenzoic acid,
Trimethylene glycol, propylene glycol, 1,
Aliphatic diols such as 4-butanediol, 1,3-butanediol, neopentyl glycol, and 1,6-hexanediol; alicyclic diols such as cyclohexanedimethanol and tricyclodecanedimethanol; bisphenol A; bisphenol S; Examples thereof include aromatic diols such as tetrabromobisphenol, hydroquinone, and dihydroxydiphenyl.

However, in the present invention, a homopolymer of polyethylene terephthalate is particularly preferred.

The polyester of the present invention may contain, if necessary, a stabilizer such as an ultraviolet absorber, an antioxidant, a plasticizer,
Lubricants, flame retardants, release agents, pigments and the like can be appropriately compounded.

The polyester used in the method of the present invention is 3
It is necessary that the intrinsic viscosity measured with a mixed solvent of p-chlorophenol / 1,1,2,2-tetrachloroethane (40/60 weight ratio) at 5 ° C. is 1.2 or more. If the intrinsic viscosity is less than 1.2, the molecular weight is insufficient, and a polyester fiber having the desired mechanical properties cannot be obtained. The intrinsic viscosity is preferably 1.5 or more, and more preferably 1.8 or more.

Such a high-molecular-weight polyester having a high intrinsic viscosity can be obtained by a conventionally known solid-phase polymerization method.

The method for producing a polyester fiber according to the present invention comprises:
The high-molecular-weight polyester is dissolved in a single solvent of p-chlorophenol or a mixed solvent of p-chlorophenol and another chlorinated solvent to prepare a spinning dope, which is fiberized by wet spinning or semi-dry semi-wet spinning. It is.

Here, "other chlorinated solvents" are 1,1,
It refers to a single or a mixture of 2,2-tetrachloroethane, chloroform and dichloromethane. Of these, 1,1,2,2-tetrachloroethane is preferably used alone from the viewpoint of solubility of the polymer.

The mixing ratio of p-chlorophenol to other chlorinated solvent is preferably 20 to 100% by weight of p-chlorophenol and 80 to 0% by weight of chlorinated solvent. A more preferred composition range is p
-Chlorophenol is 40 to 100% by weight, and other chlorinated solvents are 60 to 0% by weight.

The concentration of the polymer in the spinning dope used in the method of the present invention is preferably 5 to 50% by weight. Polymer concentration of 5
If it exceeds 0% by weight, complete dissolution of the polymer becomes difficult.
On the other hand, when the content is less than 5% by weight, the spinning solution tends to have too low a viscosity and the spinnability tends to decrease.

The spinning solution thus prepared is discharged from a spinning nozzle using an extruder, and then introduced into a coagulation bath to form a yarn, thereby forming a gel fiber.
As the spinning method, any of a completely wet method in which a spinning solution is discharged in a coagulation bath and a semi-dry semi-wet method in which the spinning solution is once discharged into the air and then introduced into the coagulation bath can be employed. At this time, 60% of ethylene glycol was used as a coagulation bath solution.
As described above, by using a liquid containing preferably 80% or more, a gel fiber which is homogeneous, has excellent transparency, and has extremely high stretchability can be formed.

Other components that can be added to ethylene glycol as a coagulation bath solution include methanol, ethanol,
Acetone, water, isobutyl alcohol, n-butyl alcohol, propylene glycol, glycerin, tetrachloroethane, chloroform, dichloromethane, and the like can be used. The temperature of the coagulation bath is not particularly limited, but may be 2
0-100 ° C is preferably used.

The gel fiber thus obtained can be stretched in one step or multiple steps in an ethylene glycol bath or in air. The stretching temperature is not particularly limited.
0-100 ° C is preferably used.

The gel fibers can be extracted and desorbed in an ethylene glycol bath, washed with water to desorb ethylene glycol and residual solvent, and dried to form dense solid fibers. it can. The dried solid fibers (hereinafter referred to as dried yarns) can be drawn and heat-treated in the same manner as polyester fibers obtained by ordinary melt spinning.

At this time, it is preferable to further stretch the dried yarn after stretching the gel fiber. The stretching ratio is preferably at least 5 times, more preferably at least 6 times, as the total stretching ratio. Here, the total draw ratio is the product of the draw ratio of the gel fiber and the draw ratio of the dried yarn. Thus,
By appropriately selecting the stretching conditions, it is possible to obtain a high-strength polyester fiber having a tensile strength exceeding 10 g / d, which has been difficult to produce industrially by a conventional method.

[0022]

As described above, according to the method of the present invention, a polyester having a high degree of polymerization is spun by a wet method or a semi-dry semi-wet method in a general-purpose solvent system while preventing a decrease in molecular weight. By forming a gel fiber and drawing the gel fiber and the dried yarn at a high magnification to develop a high fiber orientation, a polyester fiber having extremely excellent mechanical properties can be produced.

The high molecular weight polyester fiber obtained by the method of the present invention has excellent mechanical properties,
It can be widely used for industrial materials including reinforcing materials such as belts.

[0024]

Next, embodiments of the present invention will be described in detail. However, the following examples do not limit the present invention. The physical property values used in the present invention are measured by the following methods.

(A) Intrinsic viscosity: Measured at 35 ° C. using a mixed solvent of p-chlorophenol / 1,1,2,2-tetrachloroethane (40/60 weight ratio).

(B) Tensile Properties Tensile strength, elongation at break, and Young's modulus of the fiber were determined by performing a constant-speed tensile test on a single fiber having a test length of 25 mm at a tensile speed of 100% per minute.

[0027]

Example 1 Polyethylene terephthalate having an intrinsic viscosity of 2.37 obtained by solid-phase polymerization under a nitrogen stream at 240 ° C. was mixed with p-chlorophenol and 1,1,2,2-tetrachloroethane mixed solvent (40 / 60 weight ratio) to obtain a solution having a polymer concentration of 20% by weight.
This polymer solution was mixed with a plunger extruder for 50 minutes.
The mixture was extruded at 50 ° C. into an ethylene glycol bath at 50 ° C. to obtain a gel fiber. At this time, the spinning nozzle has a diameter of 0.15 mm,
The ejection linear velocity was 2 m / min.

After the obtained gel fiber is washed with boiling water and dried on a drying roller at a constant length, it is quadrupled at 120 ° C.
Stretched 1.5 times at 00 ° C.

The tensile strength of the obtained drawn fiber is 10.5 g.
/ D and Young's modulus were 100 g / d. The intrinsic viscosity of the fiber was 2.10.

[0030]

Example 2 A gel fiber was prepared in exactly the same manner as in Example 1, the gel fiber was stretched 5.0 times in ethylene glycol, washed with boiling water, and dried on a drying roller at a constant length.
The obtained dried yarn was further stretched 1.3 times at 200 ° C.

The tensile strength of the obtained drawn fiber is 11.0 g.
/ D and Young's modulus were 130 g / d. The intrinsic viscosity of the fiber was 2.15.

[0032]

Example 3 A polymer solution prepared in the same manner as in Example 1 was once discharged into the air using a plunger type extruder, and then introduced into an ethylene glycol bath at 50 ° C. for coagulation.

After the obtained gel fiber is washed in boiling water, it is dried at a constant length on a drying roller, and is quadrupled at 120.degree.
The film was stretched 1.6 times at 0 ° C.

The tensile strength of the obtained drawn fiber was 10.7.
g / d and Young's modulus 110 g / d. The intrinsic viscosity of the fiber was 2.0.

Continuation of the front page (56) References JP-A-61-207616 (JP, A) JP-A-62-223333 (JP, A) JP-A-62-30024 (JP, A) JP-A-4-65457 (JP) , A) JP-A-4-73212 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D01F 6/62 301 D01F 6/62 302

Claims (2)

(57) [Claims] The method according to claim 1 polyesters intrinsic viscosity of 1.2 or more substantially ethylene terephthalate units, was dissolved in a mixed solvent of p- chlorophenol or p- chlorophenol and other chlorinated solvents, as a coagulation bath ethylene
A method for producing high molecular weight polyester fiber, comprising performing wet or semi-dry semi-wet spinning using a liquid bath containing glycol . Wherein the gel fibers Tsu take-off from the coagulation bath, according to claim 1, in that state, or washed with water dried, and wherein the stretching in one step or more than five times the total draw ratio in two or more stages 3. The method for producing a high-molecular-weight polyester fiber according to 1.