JP3217900B2 - Polyethylene naphthalate fiber and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is useful for industrial materials and the like.
The present invention relates to a polyethylene naphthalate fiber having high strength, high elastic modulus, low elongation, and high dry heat shrinkage, and a method for producing the same.

[0002]

2. Description of the Related Art Polyethylene naphthalate fibers containing ethylene-2,6-naphthalate units as main constituents exhibit high strength, high modulus of elasticity and excellent thermal dimensional stability. It is expected to show performance exceeding polyethylene terephthalate fiber in such fields.

On the other hand, polyethylene naphthalate fiber is
Due to the high thermal dimensional stability, the dry heat shrinkage is low, and the use may be restricted depending on the application.

In order to solve such a problem, for example, Japanese Patent Publication No. Sho 56-42682, Japanese Patent Publication No. Sho 52-5612 or Japanese Patent Application Laid-Open No. Sho 50-46922 discloses that the boiling water shrinkage ratio is sufficiently high. Polyethylene naphthalate fibers having a high dry heat shrinkage are disclosed, but all have a strength of less than 4 g / de, and cannot be said to have high strength.

That is, it is extremely difficult to increase only the dry heat shrinkage rate while maintaining the high strength, high elasticity and high heat resistance inherent in polyethylene naphthalate fiber in the prior art.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to maintain a high strength, a high elastic modulus, and a low elongation, which are useful for industrial materials. An object of the present invention is to provide a polyethylene naphthalate fiber having a dry heat shrinkage and a method for producing the same.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by specifying the microstructure, particularly the crystal size, of polyethylene naphthalate fiber, high strength, high elastic modulus, It has been found that a polyethylene naphthalate fiber having a high dry heat shrinkage ratio can be obtained while maintaining a low elongation.

Thus, according to the present invention, ethylene-2,
It is made of polyethylene naphthalate containing 6-naphthalate units in an amount of 90 mol% or more, and has a crystal size D ₁ of 65 Å or less and a crystal size D ₂ of 45 Å or less and satisfies the following (a) to (e). A featured polyethylene naphthalate fiber is provided. (A) Dry heat shrinkage at 150 ° C is 8.0% or more (b) Dry heat shrinkage at 180 ° C is 10.0% or more (c) Strength is 8.0 g / de or more (d) Elongation (E) Elastic modulus is 210 g / de or more (where D ₁ and D ₂ are 15 to 16 ° and 26 to ₂ in the wide-angle X-ray diffraction diagram in the equator direction, respectively).
(This is a value calculated from the half width of the diffraction peak intensity appearing at 7 °.)

According to the present invention, there is further provided a method for producing a polyethylene naphthalate fiber, comprising the steps of: A method is provided.

(A) Polyethylene naphthalate containing at least 90 mol% of ethylene-2,6-naphthalate unit is melt-spun and has an intrinsic viscosity of 0.5 to 1.0 and a birefringence of 0.001 to 0. No. 02, a polyethylene naphthalate undrawn yarn is obtained.

(A) The undrawn yarn is once wound or supplied continuously to the drawing step without being wound, and when the intrinsic viscosity is 0.5 to 0.7, the surface temperature is 153 to 155 ° C. And the first stretching roller having a surface temperature of 170 ° C. or less, and the intrinsic viscosity exceeds 0.7.
In the case of 0 or less, the first-stage stretching of 5.0 to 7.0 times is performed by a heating supply roller having a surface temperature of 153 to 165 ° C and a first stretching roller having a surface temperature of 190 ° C or less.

(C) Next, after performing the second-stage stretching of 1.0 to 1.3 times with the first stretching roller and the second stretching roller, it is cooled and wound up by the second stretching roller.

The polyethylene naphthalate referred to in the present invention means that ethylene-2,6-naphthalate unit is 90 mol%.
A copolymer containing the appropriate third component at a ratio of 10 mol% or less may be used. Generally, polyethylene-2,6-naphthalate is synthesized by polymerizing naphthalene-2,6-dicarboxylic acid or a functional derivative thereof in the presence of a catalyst under appropriate reaction conditions. At this time, polyethylene-2,6-
If one or more appropriate third components are added before the completion of the polymerization of naphthalate, a copolymerized polyethylene naphthalate is synthesized.

Suitable third components include (a) a compound having two ester-forming functional groups, for example, oxalic acid,
Aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and dimer acid; alicyclic dicarboxylic acids such as cyclopropanedicarboxylic acid, cyclobutanedicarboxylic acid and hexahydroterephthalic acid; phthalic acid, isophthalic acid, naphthalene-2,7 -Aromatic dicarboxylic acids such as dicarboxylic acid and diphenyl dicarboxylic acid; carboxylic acids such as diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, and sodium 3,5-dicarboxybenzene sulfonate; glycolic acid, p-oxy Oxycarboxylic acids such as benzoic acid and p-oxyethoxybenzoic acid; propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, hexamethylene glycol, neopentylene glycol Le, p- xylylene glycol,
1,4-cyclohexanedimethanol, bisphenol A, p, p'-diphenoxysulfone-1,4-bis (β-hydroxyethoxy) benzene, 2,2-bis (p-β-hydroxyethoxyphenyl) propane, poly Oxy compounds such as alkylene glycol and p-phenylenebis (dimethylcyclohexane), or functional derivatives thereof; carboxylic acids, oxycarboxylic acids, oxy compounds and high polymerization degree compounds derived from the functional derivatives thereof; b) Compounds having one ester-forming functional group, for example, benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, methoxypolyalkylene glycol and the like.

Further, (c) a compound having three or more ester-forming functional groups, for example, glycerin, pentaerythritol, trimethylolpropane and the like can be used in a range where the polymer is substantially linear.

Needless to say, the polyester may contain additives such as a matting agent such as titanium dioxide and a stabilizer such as phosphoric acid, phosphorous acid and esters thereof.

The polyethylene naphthalate fiber of the present invention is obtained, for example, by melt-spinning the polyethylene naphthalate to obtain an undrawn yarn having a specific structure, and then drawing the undrawn yarn in at least two stages. Can be

The undrawn yarn for obtaining the polyethylene naphthalate fiber of the present invention must have an intrinsic viscosity of 0.5 to 1.0 and a birefringence of 0.001 to 0.02.

If the intrinsic viscosity is less than 0.5, high-strength fibers cannot be obtained, while if it exceeds 1.0, the melt viscosity becomes too high, resulting in poor spinning condition.

If the birefringence is less than 0.001, the spinning condition is poor, while if it exceeds 0.02, desired physical properties cannot be obtained.

A method for obtaining such an undrawn yarn is as follows.
For example, a polyethylene naphthalate chip having an intrinsic viscosity of 0.55 to 1.05 is melt-spun, and at that time, a heating tube at 250 to 400 ° C. is installed immediately below a spinneret, and a spinning draft is set at 2 mm.
0 to 300, and a method of setting the take-up speed to 1000 m / min or less.

The higher the intrinsic viscosity of polyethylene naphthalate chips, the easier it is to obtain fibers with high dry heat shrinkage,
Due to the high production cost, 0.5%
-0.7 is preferred.

The undrawn yarn is wound up once after spinning, or supplied continuously to the drawing step without being wound up, and is subjected to a drawing heat treatment apparatus in which a heating supply roller and a heating drawing roller are sequentially arranged. Stretched in steps.

That is, the intrinsic viscosity of the undrawn yarn is 0.5 to 0.5.
In the case of No. 7, the sheet is stretched 5.0 to 7.0 times by a heating supply roller having a surface temperature of 153 to 155 ° C. and a first stretching roller having a surface temperature of 170 ° C. or lower, and then the first stretching roller and the second 1.0 to 1.3 depending on the stretching roller
After being stretched twice, it is cooled and wound by a second stretching roller.

If the intrinsic viscosity of the undrawn yarn is more than 0.7 and not more than 1.0, the heating and supplying roller having a surface temperature of 153 to 165 ° C. and the first drawing roller having a surface temperature of 190 ° C. or less are used. It is stretched in the first step by 0.0 to 7.0 times,
Next, after being stretched in the second step by 1.0 to 1.3 times by the first stretching roller and the second stretching roller, it is cooled and wound by the second stretching roller.

When the surface temperature of the heat supply roller is less than the above value, sufficient stretching cannot be performed. On the other hand, when the surface temperature of the heat supply roller exceeds the above value, the desired dry heat shrinkage Can not get.

Also, when the temperature of the first stretching roller exceeds the above value, a desired dry heat shrinkage cannot be obtained.

Further, if the first-stage stretching ratio is less than 5.0 or the second-stage stretching ratio is less than 1.0, a high-strength fiber cannot be obtained, while the first-stage stretching ratio is 7.0. When the ratio exceeds the above range or when the magnification of the second stage drawing exceeds 1.3, the stretching condition is lowered.

The two-stage drawn polyethylene naphthalate fiber may be further subjected to a third stage drawing if necessary. In this case, the temperature of the second stretching roller is set to 2
The temperature may be set to 00 to 230 ° C., stretched 1.0 to 1.3 times by the second stretching roller and the third stretching roller, and then cooled and wound by the third stretching roller.

The polyethylene naphthalate fiber thus obtained must have a crystal size D ₁ of 65 Å or less and D ₂ of 45 Å or less.

Here, D ₁ and D ₂ are values calculated from the half widths of the diffraction peak intensities appearing at 15 to 16 ° and 26 to 27 °, respectively, in the wide-angle X-ray diffractogram in the equatorial direction. It is an indicator of the heat resistance of the fiber.

If D ₁ exceeds 65 angstroms or D ₂ exceeds 45 angstroms, the dry heat shrinkage of the fiber becomes too small to achieve the object of the present invention.

However, if the values of D ₁ and D ₂ are too small, the dry heat shrinkage becomes too large.
It is preferred to stop at about Angstroms and 25 Angstroms.

The dry heat shrinkage of the polyethylene naphthalate fiber at 150 ° C. and 180 ° C. must be 8% or more and 10% or more, respectively.
If the dry heat shrinkage is less than the above-mentioned value, the object of the present invention cannot be achieved. However, if it is too large, handling becomes difficult.

Further, the polyethylene naphthalate fiber has a strength of 8.0 g / de or more and an elastic modulus of 210 g / d.
e and the elongation must be 4.5% or more.

When the strength, elastic modulus and elongation are less than the above-mentioned values, it cannot be used for applications requiring high strength and high elasticity.

Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example and a comparative example is:
It was measured by the following method.

(1) Strength, Elastic Modulus and Elongation Sample length 20c according to JIS L 1013
m, and the elongation rate was 100% / min.

(2) Dry Heat Shrinkage The shrinkage at 150 ° C. and 180 ° C. for 30 minutes was determined in accordance with JIS L 1013B method (filament shrinkage).

(3) Intrinsic viscosity The undrawn yarn was dissolved in a mixed solvent of phenol and orthodichlorobenzene (volume ratio: 6: 4) and determined from the viscosity measured at 35 ° C.

(4) In the wide-angle X-ray diffraction diagram in the equator direction of the crystal sizes D ₁ and D ₂ fibers, 2Θ
Was calculated from the half widths of the diffraction peak intensities appearing at 15 to 16 ° and 26 to 27 °, respectively, using the following formula.

[0042]

(Equation 1)

Here, B is the half width of the diffraction peak intensity, Θ
Represents the diffraction angle, and λ represents the wavelength of the X-ray (1.54178 angstroms).

(5) Birefringence (Δn) The birefringence (Δn) was determined by a retardation method using a Bellec compensating center (for details, see Kyoritsu Shuppan “Lecture on Experimental Polymer Science, Physical Properties II of Polymers”).

[0045]

Example 1 Polyethylene-2,6 having intrinsic viscosity of 0.60
-A naphthalate chip with 48 holes and a hole diameter of 0.4
It is discharged at a spinneret temperature of 312 ° C. from a spinneret having a circular spinning hole of 0 mm, the spinning speed is 150 m / min, and the temperature of a heating cylinder installed immediately below the spinneret is 390 ° C., and the melt spinning is performed. An undrawn yarn having a birefringence of 0.002 was obtained.

The undrawn yarn was wound eight times on a heating supply roller having a surface temperature of 153 ° C., heated, and then wound on a first drawing roller having a surface temperature shown in Table 1 to 6.5 times (Experiment N).
O. 1-5) or 6.8 times (Experiment Nos. 6-8) in the first step.

Subsequently, the first stretching roller and the second stretching roller at room temperature were used to increase the magnification by 1.0 times (Experiment Nos. 1 to 1).
5) or 1.05 times (Experiment Nos. 6 to 8) in the second step and wound. Table 1 shows the physical properties of the obtained polyethylene naphthalate fiber.

[0048]

[Table 1]

[0049]

Example 2 Example 1 was carried out in the same manner as in Example 1 except that the surface temperatures of the heating supply roller and the first stretching roller, and the stretching ratios of the first and second stages were changed as shown in Table 2. did. Table 2 shows the physical properties of the obtained polyethylene naphthalate fiber.

[0050]

[Table 2]

[0051]

Example 3 Polyethylene-2,6 having intrinsic viscosity of 0.63
-Use a naphthalate chip with 12 holes and a hole diameter of 0.2
It is discharged from a spinneret having a circular spinning hole of 5 mm at a spinneret temperature of 313 ° C., melt-spun at a spinning speed of 550 m / min, and a temperature of a heating cylinder installed immediately below the spinneret of 390 ° C., with an intrinsic viscosity of 0.61. An undrawn yarn having a birefringence of 0.008 was obtained.

The undrawn yarn was wound eight times around a heating supply roller having a surface temperature of 153 ° C. and heated, and then wound around a first drawing roller having a surface temperature shown in Table 3 to give a first 5.98 times the first drawn roller.
Step stretching was performed.

Subsequently, the film was stretched in the second stage by 1.03 times by a first stretching roller and a second stretching roller at room temperature, and wound up. Table 3 shows the physical properties of the obtained polyethylene naphthalate fiber.

[0054]

[Table 3]

[0055]

Example 4 Polyethylene-2,6 having an intrinsic viscosity of 0.83
-A naphthalate chip with 48 holes and a hole diameter of 0.4
It is discharged from a spinneret having a circular spinning hole of 0 mm at a spinneret temperature of 324 ° C., melt-spun at a spinning speed of 150 m / min, and a temperature of a heating cylinder installed immediately below the spinneret of 390 ° C., with an intrinsic viscosity of 0.80. An undrawn yarn having a birefringence of 0.0035 was obtained.

The undrawn yarn was wound eight times on a heating supply roller having the surface temperature shown in Table 4, heated, and then wound on a first drawing roller having the surface temperature shown in Table 4 to 6.5 times. It was stretched in one step.

Subsequently, the first stretching roller and the second stretching roller at room temperature were stretched in the second stage by 1.1 times and wound up. Table 4 shows the physical properties of the obtained polyethylene naphthalate fiber.

[0058]

[Table 4]

[0059]

According to the present invention, it is possible to obtain polyethylene naphthalate fibers having a high dry heat shrinkage ratio while maintaining high strength, high elastic modulus and low elongation. It can be suitably used for industrial materials such as cloth, sports / leisure, and the like.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-48-77116 (JP, A) JP-A-50-94225 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01F 6/62

Claims (2)

(57) [Claims] 1. A polyethylene naphthalate containing at least 90 mol% of ethylene-2,6-naphthalate units, having a crystal size D ₁ of 65 Å or less and a crystal size D ₂ of 45 Å or less. A polyethylene naphthalate fiber satisfying (e). (A) Dry heat shrinkage at 150 ° C is 8.0% or more (b) Dry heat shrinkage at 180 ° C is 10.0% or more (c) Strength is 8.0 g / de or more (d) Elongation (E) Elastic modulus is 210 g / de or more (where D ₁ and D ₂ are 15 to 16 ° and 26 to ₂ in the wide-angle X-ray diffraction diagram in the equator direction, respectively).
(This is a value calculated from the half width of the diffraction peak intensity appearing at 7 °.) 2. A method for producing a polyethylene naphthalate fiber, comprising the steps of (a) to (c) described below when producing the polyethylene naphthalate fiber according to claim 1. (A) Polyethylene naphthalate containing at least 90 mol% of ethylene-2,6-naphthalate units is melt-spun and has an intrinsic viscosity of 0.5 to 1.0 and a birefringence of 0.001 to 0.001.
An undrawn polyethylene naphthalate yarn of 0.02 is obtained. (A) winding the undrawn yarn once, or continuously feeding the undrawn yarn to the drawing step without winding, so that the intrinsic viscosity is 0.5 to 0.7;
In the case of (1), a heating supply roller having a surface temperature of 153 to 155 ° C. and a first stretching roller having a surface temperature of 170 ° C. or less are used. If the intrinsic viscosity is more than 0.7 and 1.0 or less, the surface temperature is 153. 5.0 by a heating supply roller at １６165 ° C. and a first stretching roller having a surface temperature of 190 ° C. or lower.
The first-stage stretching of up to 7.0 times is performed. (C) Next, after performing the second-stage stretching of 1.0 to 1.3 times with the first stretching roller and the second stretching roller, the second stretching is performed.
It is cooled by a stretching roller and wound up.