JP2007063685A - Method for producing high viscosity polyamide staple fibers - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing high viscosity polyamide staple fibers, by which the high viscosity polyamide staple fibers having difficulty in being produced by a melt-spinning method due to gelation and the like can easily efficiently be produced. <P>SOLUTION: This method for producing the high viscosity polyamide staple fibers is characterized by heating polyamide staple fibers comprising poly(hexamethylene adipamide) or poly(ε-caproamide) in an amount of at least 90% based on the total weight and having a sulfuric acid relative viscosity of 2.0 to 3.6 at 50 to 200°C in an atmosphere containing an oxygen-containing compound in an amount of ≤0.1 wt.% to obtain the polyamide staple fibers having a sulfuric acid relative viscosity of 4.5 to 5.8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a high-viscosity polyamide fiber having high wear resistance, high weather resistance, and high durability used for clothing, materials, agriculture, fishery, and automotive parts.

  Conventionally, polyamide fibers having a sulfuric acid relative viscosity ηr of 2.8 to 3.2 (low-viscosity polyamide fibers) have characteristics such as wear resistance, weather resistance, and durability. It was used for fishing and automotive parts. In order to obtain higher wear resistance, medium viscosity polyamide fibers having a sulfuric acid relative viscosity ηr of 3.2 to 4.5 have been used as members of cleaning tools such as abrasives and mops. Furthermore, high-viscosity polyamide fibers (sulfuric acid relative viscosity ηr is 4.5 to 5.8) having higher wear resistance are required for sports apparel and materials.

Therefore, conventionally, as in Patent Document 1, for example, a phenol compound having an alkyl group and / or an aryl group, a phosphite compound having an alkyl group and / or an aryl group, and a phosphonate compound having an alkyl group and / or an aryl group in advance. A polymer chip made of polyamide is prepared by adding a phosphite compound having an alkyl group and / or an aryl group, an alkali metal and a mixture thereof as a stabilizer or a catalyst additive and kneading under a reduced pressure with a biaxial screw. A polyamide fiber having a relative viscosity of sulfuric acid ηr of 3.2 to 3.8 was produced by melt spinning the polymer chip.
Japanese Patent No. 2853335 (Claim 1)

  In Patent Document 1, although a chip made of a polymer whose viscosity is increased by a thickener containing a phosphorus compound can be obtained, a high sulfuric acid relative viscosity ηr of 4.5 or more is required to obtain a polyamide fiber having high wear resistance. Melt spinning was not possible using polymer chips of viscosity. That is, the viscosity at the time of polymer melting was too high to be spun and could not be made into fibers. Therefore, when the melt viscosity of the polymer is lowered by increasing the temperature at the time of melting, the polymer is decomposed or gelled, and it is impossible to obtain a fiber having the characteristics required for the fiber.

  The inventors of the present invention have solved the above-mentioned problems of the prior art, studied a method for producing a high-viscosity polyamide short fiber excellent in wear resistance, weather resistance and durability, and reached the present invention.

In order to achieve the above-described object, the present invention has the following configuration.
That is, the present invention provides a polyamide short fiber in which at least 90% or more of the total weight is composed of poly (hexamethylene adipamide) or poly (ε-caproamide), and sulfuric acid relative viscosity ηr is 2.0 to 3.6. A high-viscosity polyamide characterized by obtaining a polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.5 to 5.8 by heating at 50 to 200 ° C. in an atmosphere containing an oxygen-containing compound of 0.1% or less. It is a manufacturing method of a short fiber.

Furthermore, the polyamide short fiber contains 0.01 to 1 wt% of at least one phosphorus compound as an additive based on the total weight of the fiber,
Heating is performed under a pressure of 0.0001 to 1.0 MPa,
Heating is performed in the presence of a gas selected from nitrogen, carbon dioxide, argon and helium;
The polymer constituting the polyamide short fiber is a poly (hexamethylene adipamide) homopolymer or a poly (ε-caproamide) homopolymer;
Is a preferred embodiment of the present invention.

  According to the present invention, it is possible to obtain high-viscosity polyamide short fibers having high wear resistance, high weather resistance, and high durability used for clothing, materials, agriculture, fisheries, and automobile parts.

  In the present invention, the high-viscosity polyamide short fiber means one having a sulfuric acid relative viscosity ηr of 4.5 to 5.8, and the medium viscosity polyamide short fiber has a sulfuric acid relative viscosity ηr of 3.2 to 4.5. A low-viscosity polyamide short fiber means one having a sulfuric acid relative viscosity ηr of 2.8 to 3.2.

  In the present invention, a low-viscosity polyamide short fiber that has already been spun is heated at a temperature equal to or lower than the polymer melting point in an atmosphere with a small amount of oxide derived from an oxygen-containing compound, thereby performing solid-state polymerization in a fiber state, High viscosity fibers can be obtained. That is, conventionally, solid phase polymerization is usually performed with a polymer chip, and solid phase polymerization has not been performed in a fiber state. When solid state polymerization was performed in the state of fibers, an imbalance occurred between the inside and the outside of the winding when wound on a bobbin or drum, and solid phase polymerization could not be performed uniformly. Therefore, conventional solid state polymerization has been carried out in a polymer chip state, not in a fiber state. Contrary to conventional common sense, the present invention uses short fibers in a state where no stress is applied, and by controlling the content of the oxygen-containing compound, uniform solid-state polymerization with the fibers becomes possible for the first time, wear resistance The fiber excellent in the property, weather resistance, and durability was obtained very efficiently. Moreover, in the present invention, high-viscosity polyamide short fibers can be stably produced without causing decomposition or gelation during melt spinning.

  The manufacturing method of the raw material polyamide short fiber used by this invention is not specifically limited, What was manufactured by the conventional method can be used.

  In addition, as a method for measuring the relative viscosity of sulfuric acid in the present invention, a method for measuring the viscosity number of polyamide described in JIS K 6933 is used. That is, after 0.25 g of polyamide short fibers are dissolved in 98% concentrated sulfuric acid at 25 ° C., the relative viscosity is calculated based on the rate of dropping with an Ostwald viscometer.

  In the polyamide short fiber having a relative viscosity ηr of sulfuric acid of 2.0 to 3.6 used as a raw material in the present invention, at least 90% or more of the total weight is made of poly (hexamethylene adipamide) or poly (ε-caproamide). Preferably, 95% or more is made of poly (hexamethylene adipamide) or poly (ε-caproamide). The polyamide short fiber used as a raw material preferably has a sulfuric acid relative viscosity ηr of 2.5 to 3.4.

  In the present invention, it is important to heat the raw material polyamide short fibers in an atmosphere containing 0.1 wt% or less of an oxygen-containing compound. Here, the oxygen-containing compound refers to a gas that adversely affects solid phase polymerization by releasing oxygen, and specifically refers to water, oxygen, and ozone. Carbon dioxide contains oxygen but is not included in the oxygen-containing compound of the present invention because it does not adversely affect solid phase polymerization. In the present invention, it is necessary to heat these oxygen-containing compounds under an atmosphere of 0.1 wt% or less, that is, under a condition that the weight fraction in the gas phase is 0.1 wt% or less. Although the lower limit is desirable, it is 0.001 wt% in the current technology. The heating temperature is 50 to 200 ° C, preferably 80 ° C to 180 ° C, and more preferably 140 ° C to 180 ° C. Polyamide polymerization proceeds with heating, and the relative viscosity of the polyamide fibers increases. Thus, a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.5 to 5.8 is obtained. The high-viscosity polyamide short fibers preferably have a sulfuric acid relative viscosity of 4.5 to 5.2, more preferably 4.6 to 5.0. In the present invention, heating is performed until a high-viscosity polyamide having such a sulfuric acid relative viscosity is obtained.

  By the method of the present invention, stable high-viscosity polyamide short fibers can be produced without causing decomposition or gelation during melt spinning. In other words, low viscosity polyamide short fibers that have already been spun are heated at a temperature below the polymer melting point in an atmosphere with a small amount of oxides caused by oxygen-containing compounds, and solid-state polymerization in the fiber state is carried out, thereby achieving high viscosity. Fiber can be obtained. Conventionally, solid phase polymerization is usually performed with a polymer chip, and solid phase polymerization has not been performed in a fiber state. It was thought that solid-phase polymerization could not be performed uniformly when solid-phase polymerization was performed in a fiber state. However, in the present invention, by using short fibers in an unstressed state and controlling the content of the oxygen-containing compound, uniform solid-state polymerization with the fibers becomes possible for the first time, wear resistance, weather resistance Thus, highly durable fibers were obtained very efficiently.

  In the present invention, the raw material polyamide short fiber having a sulfuric acid relative viscosity ηr of 2.0 to 3.6 further contains at least one phosphorus compound or a mixture thereof as an additive, preferably the total weight of the fiber. It is preferable to contain 0.01 to 1 wt%, more preferably 0.1 to 1 wt%.

  In the present invention, heating is preferably performed under a pressure of 0.0001 to 1.0 MPa. In the present invention, heating is performed in an atmosphere containing 99.0 to 99.9 wt% of a gas selected from an inert gas such as nitrogen, carbon dioxide, argon or helium. The rate is preferably 99.0 to 99.9 wt%. As described above, carbon dioxide is not included in the oxygen-containing compound referred to in the present invention.

  In the present invention, at least 95%, preferably 98% or more, more preferably 99% or more of the short polyamide fibers are poly (hexamethylene adipamide) homopolymer or poly (ε-caproamide) homopolymer. Preferably it consists of. Further, the polymer constituting the polyamide short fiber is most preferably a poly (hexamethylene adipamide) homopolymer or a poly (ε-caproamide) homopolymer.

  In the present invention, it is preferable that the polyamide short fiber contains 0.01 to 1 wt% of at least one phosphorus compound as an additive based on the total weight of the fiber. Here, a phenyl group-containing phosphate ester is preferably used as the phosphorus compound. Specific examples include bis (2,4-dicumylphenyl) pentaerythritol diphosphite, tris (2,4-tert.butylphenyl) phosphite, and the like. The presence of these phosphorus compounds can further promote solid phase polymerization. The phosphorus compound used in the present invention can be used together with other additives. Other preferred additives that can be used in combination include N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxyhydrocinnamamide, 1,3,5-trimethyl-2,4,6. -Tris (3,5-tert-butyl-4-hydroxybenzyl) benzene-N, N'-hexamethylenebis (3,5-tert-butyl-4-hydroxyhydrocinnamamide), and the like.

  These additives are preferably contained in an amount of 0.01 to 1% by weight, more preferably 0.1 to 1% of the total weight of the fiber.

  Moreover, the method of heating to 50-200 degreeC is a manufacturing method of the high viscosity polyamide short fiber which is preferably a microwave, an ultrasonic wave, and a far infrared ray.

  The present invention will be specifically described below with reference to examples.

Example 1
0.05 part by weight of bis (2,4-dicumylphenyl) pentaerythritol diphosphite and N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) 05 parts by weight and 1,3,5-trimethyl-2,4,6-tris (3,5-tert.butyl-4-hydroxybenzyl) benzene-N, N′-hexamethylenebis (3,5-tert. Butyl-4-hydroxyhydrocinnamamide) 0.05 parts by weight, tris (2,4-tert.butylphenyl) phosphite 0.05 parts by weight, and poly (hexamethylene adipamide) 95.0 parts by weight A polyamide composition comprising: a spin hole at 300 ° C. through a 300-hole spinneret with a hole diameter of 0.35 mm, and once placed in a can at 1200 m / min, To obtain a drawn yarn.

  Subsequently, the obtained undrawn yarn was subjected to two-stage drawing using a heating roll at 80 ° C. at a draw ratio of 2.7 times, and 8 to 15 pieces / A 25 mm mechanical crimp is applied, an oil agent is applied by spraying, the obtained tow is dried at a temperature of 100 ° C. for 10 minutes, cut to a length of 50 mm, and a sulfuric acid relative viscosity ηr of a fiber length of 15 dTex of 50 mm is obtained. 3.5 short fibers were obtained.

  The obtained short fiber was subjected to an atmospheric pressure of 0.1 MPa under the condition that the total amount of water, oxygen, and ozone was 0.05 wt% in the gas phase and 99.95% by weight of nitrogen. Then, a high viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 5.0 was obtained by heating at 180 ° C. for 24 hours with an electric heater.

Example 2
In the same manner as in Example 1 except that poly (hexamethylene adipamide) is changed to poly (ε-caproamide) in Example 1, a short fiber having a 15dTex fiber length of 50 mm and a sulfuric acid relative viscosity ηr of 2.6 Got. The obtained short fibers were heated for 36 hours in the same manner as in Example 1 to obtain high-viscosity polyamide short fibers having a sulfuric acid relative viscosity ηr of 4.6.

Example 3
In Example 1, a short fiber having 15 dTex fiber length of 50 mm and sulfuric acid relative viscosity ηr of 3.5 was obtained in the same manner as Example 1 except that no additive was contained. The obtained short fibers were heated in the same manner as in Example 1 except that nitrogen was changed to carbon dioxide, to obtain high-viscosity polyamide short fibers having a sulfuric acid relative viscosity ηr of 4.5.

Example 4
In Example 2, a short fiber having a fiber length of 15 dTex and a fiber relative length ηr of 2.6 having a fiber length of 50 mm was obtained in the same manner as Example 2 except that the additive was not contained. The obtained short fibers were heated in the same manner as in Example 1 except that nitrogen was changed to carbon dioxide, to obtain high-viscosity polyamide short fibers having a sulfuric acid relative viscosity ηr of 4.5.

Example 5
A raw material short fiber of 15 dTex with a fiber length of 50 mm and a relative viscosity ηr of 3.5 obtained in Example 1 is the same as in Example 1 except that nitrogen is changed to helium and the atmospheric pressure is changed to 0.01 MPa. By heating, a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.8 was obtained.

Example 6
A raw material short fiber having a 15 dTex fiber length of 50 mm and a relative viscosity ηr of 3.5 obtained in Example 1 was changed in the same manner as in Example 1 except that nitrogen was changed to argon and the atmospheric pressure was changed to 0.01 MPa. By heating, a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.8 was obtained.

Example 7
The raw material short fiber having a 15 dTex fiber length of 50 mm and a sulfuric acid relative viscosity ηr of 3.5 obtained in Example 1 was heated in the same manner as in Example 1 except that the atmospheric pressure was changed to 0.01 MPa. A high-viscosity polyamide short fiber having a viscosity ηr of 4.8 was obtained.

Example 8
The raw material short fiber having a 15dTex fiber length of 50 mm and a sulfuric acid relative viscosity ηr of 2.6 obtained in Example 2 was heated in the same manner as in Example 2 except that the atmospheric pressure was changed to 0.01 MPa. A high-viscosity polyamide short fiber having a viscosity ηr of 4.6 was obtained.

Example 9
A raw material short fiber having a 15 dTex fiber length of 50 mm and a relative viscosity ηr of 3.5 obtained in Example 1 is the same as in Example 1 except that the atmospheric pressure is changed to 0.01 MPa and heating is performed by microwaves. To obtain a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.8.

Example 10
A raw material short fiber having a fiber length of 15 dTex of 50 mm and a relative viscosity of sulfuric acid ηr of 3.5 obtained in Example 1 is the same as that of Example 1 except that the atmospheric pressure is changed to 0.01 MPa and heating is performed with ultrasonic waves. To obtain a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.8.

Example 11
Same as Example 1 except that the raw material short fiber of 15 dTex fiber length 50 mm and relative viscosity ηr of 3.5 obtained in Example 1 having a relative viscosity ηr of 3.5 is changed to 0.01 MPa and heating is performed by far infrared rays. To obtain a high-viscosity polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.8.

Example 12
In Example 1, 90.0 parts by weight of poly (hexamethylene adipamide) and 5.0 parts by weight of poly (ε-caproamide) were prepared from a polyamide composition comprising 95.0 parts by weight of poly (hexamethylene adipamide). A short fiber having a 15 dTex fiber length of 50 mm and a sulfuric acid relative viscosity ηr of 2.2 was obtained in the same manner as in Example 1 except that the change was changed to The obtained short fibers were heated in the same manner as in Example 1 to obtain high-viscosity polyamide short fibers having a sulfuric acid relative viscosity ηr of 4.5.

Example 13
The raw material short fiber having a 15 dTex fiber length of 50 mm and a sulfuric acid relative viscosity ηr of 3.5 obtained in Example 1 was heated in the same manner as in Example 1 except that the heating time was 36 hours. A high-viscosity polyamide short fiber having ηr of 5.5 was obtained.

Comparative Example 1
0.05 part by weight of bis (2,4-dicumylphenyl) pentaerythritol diphosphite and N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) 05 parts by weight and 1,3,5-trimethyl-2,4,6-tris (3,5-tert.butyl-4-hydroxybenzyl) benzene-N, N′-hexamethylenebis (3,5-tert. Butyl-4-hydroxyhydrocinnamamide) 0.05 parts by weight, tris (2,4-tert.butylphenyl) phosphite 0.05 parts by weight, and poly (hexamethylene adipamide) 95.0 parts by weight A chip having a sulfuric acid relative viscosity ηr of 4.5 was obtained by kneading the polyamide composition comprising: However, because of its high viscosity, melt spinning could not be performed from a 300-hole spinneret with a hole diameter of 0.35 mm at 280 ° C. Although melt spinning was possible for the first time at 300 ° C., the decomposition of the polymer progressed. Undrawn yarn could not be obtained.

Comparative Example 2
In Example 1, an additive was not included and poly (hexamethylene adipamide) having a low degree of polymerization of sulfuric acid relative viscosity ηr1.8 was used in the same manner as in Example 1 except that 15 dTex fiber length of 50 mm. A short fiber having a sulfuric acid relative viscosity ηr of 1.8 was obtained. The obtained short fiber was heated in the same manner as in Example 1 except that nitrogen was changed to carbon dioxide and the atmospheric pressure was changed to 0.1 MPa. As a result, only polyamide short fibers having a sulfuric acid relative viscosity ηr of 3.5 were obtained.

Comparative Example 3
In Example 1, a short fiber having 15 dTex fiber length of 50 mm and sulfuric acid relative viscosity ηr of 3.5 was obtained in the same manner as Example 1 except that no additive was contained. The obtained short fibers were heated in the same manner as in Example 1 except that the heating was performed in an atmosphere in the atmospheric phase (20 wt% oxygen content). As a result, an oxidation reaction with oxygen in the air progressed, and only polyamide short fibers having a sulfuric acid relative viscosity ηr of 3.4 were obtained.

Comparative Example 4
Heating of the raw material short fiber having a 15 dTex fiber length of 50 mm and a relative viscosity ηr of 3.5 obtained in Example 1 was changed to heating at 45 ° C. with an electric heater, and was heated in the same manner as in Example 1. As a result, since the heating temperature was low, only polyamide short fibers having a sulfuric acid relative viscosity ηr of 3.5 were obtained.

Comparative Example 5
The result of heating the raw material short fiber of 15 dTex with a fiber length of 50 mm and a relative viscosity of sulfuric acid ηr of 3.5 obtained in Example 1 in the same manner as in Example 1 except that the heating is changed to 210 ° C. with an electric heater. The polymer melted and polyamide short fibers could not be obtained.

The high-viscosity polyamide fiber of the present invention is used for applications requiring high wear resistance, high weather resistance and high durability used for clothing, materials, agriculture, fishery, and automotive parts. In addition, it can be used for sports applications and material applications such as mops, gloves, ropes, and automobile interior materials used as cleaning tools, and interior materials such as floor materials that are heavily worn, mirror polishing of semiconductor parts, Examples include mirror polishing of hard disk storage materials. Examples of sports applications include heavily worn clothing parts, shoes, and sports equipment.

Claims (5)

  At least 90% or more of the total weight is made of poly (hexamethylene adipamide) or poly (ε-caproamide), and a polyamide short fiber having a sulfuric acid relative viscosity ηr of 2.0 to 3.6 has an oxygen-containing compound of 0. A process for producing a high-viscosity polyamide short fiber, characterized in that a polyamide short fiber having a sulfuric acid relative viscosity ηr of 4.5 to 5.8 is obtained by heating at 50 to 200 ° C. in an atmosphere of 1 wt% or less. .   The method for producing high-viscosity polyamide short fibers according to claim 1, wherein the polyamide short fibers contain 0.01 to 1 wt% of at least one phosphorus compound as an additive based on the total weight of the fibers.   The method for producing high-viscosity polyamide short fibers according to claim 1 or 2, wherein heating is performed under a pressure of 0.0001 to 1.0 MPa.   The method for producing a high-viscosity polyamide short fiber according to any one of claims 1 to 3, wherein the heating is performed in an atmosphere containing a gas selected from nitrogen, carbon dioxide, argon and helium.   5. The high-viscosity polyamide short fiber according to claim 1, wherein the polymer constituting the polyamide short fiber is a poly (hexamethylene adipamide) homopolymer or a poly (ε-caproamide) homopolymer. Method.