JPH09241924A - Stretched polyamide fiber and method for producing the same - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a stretched polyamide fiber having high strength, high elastic modulus and high roundness and a method for producing the same, which is useful for sports goods, industrial materials and the like. To aim. SOLUTION: Metaxylylenediamine is used as a diamine component, and adipic acid is used as a dicarboxylic acid component.
Crystalline polyamide or copolymerized polyamide (A) obtained by polymerizing a monomer containing 0 mol% or more of at least 20
% By weight, Young's modulus of 400 kgf / mm ² or more, pulling strength of 4.5 gf / D or more, knot strength of 3.5 g
A stretched polyamide fiber having a circularity of f / D or more and a circularity of 97 to 100%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a racket string, a rubber reinforcing material, a filter cloth material for papermaking, and other sports goods, industrial materials, and the like, which have high strength, high elastic modulus and roundness. The present invention relates to a highly stretched polyamide fiber and a method for producing the same.

[0002]

Polyamide fibers are used as sports goods such as racket strings, rubber reinforcing materials and filter cloth materials for papermaking, and industrial materials. In these applications, mechanical strength such as elastic modulus (Young's modulus) of fiber as a material, hooking strength, knot strength and the like is required. Further, in these applications, high circularity of the fiber is required at the time of actual use of the final product or at the time of secondary processing. That is, when the roundness of the fiber is low, it may be difficult to pass the fiber through the gaps or holes of the precisely processed article, and the compatibility with secondary processing equipment may be low. This may cause problems such as the shape of the product after processing is not uniform.

A polyamide containing an amide bond repeating unit obtained from xylylenediamine and an aliphatic dicarboxylic acid (for example, a polyamide obtained from metaxylylenediamine and adipic acid, hereinafter referred to as "polyamide MXD").
6 ”) is polyamide 6 or polyamide 6
6 has higher strength and higher Young's modulus than 6
Although it is expected to be applied to the above-mentioned applications, conventional spinning methods cannot obtain fibers with high roundness, which is an obstacle to practical use. That is, polyamide fibers used as sports goods such as racket strings, rubber reinforcing materials and filter cloth materials for papermaking, industrial materials, etc. are usually produced by the melt spinning method. Specifically, a polyamide resin is melted using a single-screw or twin-screw extruder, spun through a spinneret, and taken up in a refrigerant bath located below the spinneret surface to obtain an unstretched yarn and then spinning. Method has been adopted,
For example, in the case of polyamide 6 and polyamide 66, the roundness of the undrawn yarn is maintained by lowering the temperature of the refrigerant bath by 30 ° C. or more than the Tg of the polyamide resin to obtain undrawn yarn with suppressed crystallization. It is easy to carry out the drawing operation as it is, and a method of increasing the roundness of the resulting fiber is exclusively adopted.

On the other hand, in the case of polyamide MXD6 containing polyamide, Tg is remarkably higher than those of polyamide 6 and polyamide 66, and therefore, at the cooling temperature in the conventional polyamide melt spinning method, the undrawn yarn is rapidly solidified by rapid cooling. In addition, due to the high elastic modulus of the polyamide MXD6, the resistance between the undrawn yarn and the refrigerant in the cooling tank and the vibration at the time of take-up tend to be transmitted to the melted portion with low strength, resulting in unevenness of the yarn diameter. This will cause a decrease in roundness. Therefore, it has hitherto been extremely difficult to stably and continuously produce polyamide MXD6-containing polyamide fibers having high roundness.

[0005]

The present invention has been accomplished under the above circumstances. That is, the present invention
Polyamide M with high strength, high elastic modulus and high roundness
To provide a stretched polyamide fiber containing XD6,
Further, the present invention provides a production method capable of obtaining this stably and continuously by an ordinary melt spinning method.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object of the present invention, the present inventors have found that the above problems can be solved by performing melt spinning under specific conditions, The present invention has been completed.

That is, the present invention provides (1) a crystalline polyamide or copolymerized polyamide (A) obtained by polymerizing monomers containing metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component in an amount of 70 mol% or more. Containing at least 20% by weight and having a Young's modulus of 40
0 kgf / mm ² or more, hooking strength is 4.5 gf / D or more, knot strength is 3.5 gf / D or more and roundness is 97-
A stretched polyamide fiber characterized by being in the range of 100%,

(2) Further, the stretched polyamide fiber according to the above (1) containing 80% by weight or less of a crystalline polyamide (B) other than the polyamide (A), (3) metaxylylenediamine and dicarboxylic acid as diamine components. A polyamide resin containing at least 20% by weight of a crystalline polyamide or a copolyamide (A) obtained by polymerizing a monomer containing 70 mol% or more of adipic acid as an acid component is melted using a single-screw or twin-screw extruder. After being spun through a spinneret and taken up in a refrigerant bath located below the surface of the spinneret to obtain an unstretched yarn, a polyamide having a glass transition temperature (Tg) or higher and a melting point or lower for 2.5 to 8 is used. A method for producing a stretched polyamide fiber stretched 0.0 times, comprising: a spinneret cross-sectional area AD of a spinning machine; and a method of cooling in a refrigerant bath after being extruded from the spinning machine. The ratio AD / AM with the cross-sectional area AM of the undrawn yarn obtained by the above (hereinafter referred to as "draft rate")
Is 1.0 to 3.0, and the temperature (T) of the refrigerant bath for drawing the yarn extruded from the spinning machine through an air layer between the molten resin discharge port of the spinning machine and the cooling bath surface for cooling. Is Tg-3
A method for producing a stretched polyamide fiber having a range of 0 ≦ T ≦ Tg + 10 ° C., and

(4) At least 20 polyamides (A)
The polyamide resin containing wt% is further polyamide (A)
Other than the above, a method for producing a stretched polyamide fiber according to the above (3), which contains 80% by weight or less of a crystalline polyamide (B) is provided.

The polyamide (A) used in the present invention is
A crystalline polyamide or a copolyamide obtained by polymerizing monomers containing metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component at 70 mol% or more, respectively. When the polyamide (A) is obtained by polymerizing a monomer containing metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component in an amount of less than 70 mol%, high strength when finally formed into a fiber , Properties such as high Young's modulus are lost.

The stretched polyamide fiber used in the present invention may contain a crystalline polyamide (B) other than the above polyamide (A). Various polyamides can be used as the other crystalline polyamide (B),
Specifically, polyamide 6, polyamide 66, polyamide 6/66 (polyamide 6 component and copolymer composed of polyamide 66 component), polyamide 610, polyamide 6
12, polyamide 11, polyamide 12 and mixtures thereof can be exemplified, but in the present invention, polyamide 6, polyamide 66 or polyamide 6/66 can be preferably used. The use of these resins facilitates the adjustment of physical properties such as strength and elongation by adjusting the conditions during melt extrusion.

The stretched polyamide fiber of the present invention must contain the above polyamide (A) in an amount of 20% by weight or more. When the blending ratio of the polyamide (A) is less than 20% by weight, the properties of the polyamide MXD6 such as high strength, high elastic modulus, and crystallization rate at which spinning is easy are difficult to be reflected in the physical properties of the obtained fiber. The blending ratio of the other crystalline polyamide (B) is preferably 80% by weight or less. The drawn polyamide fiber of the present invention has a Young's modulus of 400 kgf / mm.
² or more, preferably 500 kgf / mm ² or more.
When the Young's modulus is less than 400 kgf / mm ² , deformation occurs when it is used as a racket string, a rubber reinforcing material and a papermaking filter cloth material, and the value as a product is lost.

The stretched polyamide fiber of the present invention has a hooking strength of 4.5 gf / D or more, preferably 5.0 gf / D.
That is all. When the hooking strength is less than 4.5 gf / D, when it is used as a racket string, the bent portion of the string breaks when it is mounted on the racket, and the value as a product is lost. Also, when used as a filter cloth material for papermaking, when the filter cloth material is mounted on the roll of the paper machine, a method of bending a part of the fiber of the filter cloth material and connecting the core thread through the part is adopted. Therefore, if the hooking strength is less than 4.5 gf / D, the connection portion is broken and the value as a product is lost.
Further, the knot strength of the stretched polyamide fiber of the present invention is 3.5.
gf / D, preferably 4.0 gf / D or more. When the knot strength is less than 3.5 gf / D, when the string is used as a racket string, the string breaks at the knot when the string is attached to the racket, and the value as a product is lost.

The method for producing a stretched polyamide fiber of the present invention comprises a crystalline polyamide or a copolyamide obtained by polymerizing a monomer containing metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component in an amount of 70 mol% or more. A polyamide resin containing at least 20% by weight of A) was melted using a single-screw or twin-screw extruder, spun through a spinneret, and taken up in a refrigerant bath located below the surface of the spinneret to obtain an unstretched yarn. Then, the present invention relates to a method for producing a stretched polyamide fiber which has been stretched 2.5 to 8.0 times under a temperature condition of the glass transition temperature (Tg) or more and the melting point or less of the polyamide.

In particular, in the present invention, in the above method, the draft ratio (the cross-sectional area AD of the spinneret of the spinning machine and the cross-sectional area of the undrawn yarn obtained by being extruded from the spinning machine and cooled in the cooling layer) is obtained. The ratio AD / AM with AM is 1.0 to 3.
It is 0, preferably 1.0 to 2.5. If the draft ratio is less than 1.0, it is actually difficult to make an undrawn yarn. On the other hand, if it exceeds 3.0, the influence of extrusion and cooling conditions on the undrawn yarn is amplified, so that it becomes difficult to obtain a polyamide fiber having a high roundness. In the present invention, the cross-sectional area AM of the undrawn yarn obtained by extruding from the spinning machine and then cooling in the cooling layer is defined by the following equation.

AM (cm ² ) = G / (L × ρ) Here, G (g) represents the weight of the length L (cm) of the undrawn yarn having the density ρ (g / cm ³ ).

Further, in the method of the present invention, it is necessary to interpose an air layer between the molten resin discharge port of the spinning machine and the cooling coolant bath surface in order to prevent the yarn from being rapidly cooled. If there is substantially no air layer in the meantime, problems such as yarn sway due to boiling of the refrigerant when the molten resin comes into contact with the refrigerant, or generation of vacuum bubbles caused by rapid cooling of the yarn occur. From such a point, the thickness of the air layer, that is, the distance between the molten resin discharge port of the spinning machine and the cooling bath surface for cooling (hereinafter, referred to as “air gap”) is practically at least 10 mm. Is desirable. Further, if the air layer is too thick, it may be difficult to obtain polyamide fibers having a high roundness due to the melted resin dropping down or the like.
From this point, the air gap is practically 150
mm or less. In the present invention, the air gap is more preferably 10 to 110 mm.

Further, in the method of the present invention, the polyamide yarn extruded from the spinning machine is taken into the refrigerant,
The temperature (T) of the refrigerant is Tg−30 ≦ T ≦ Tg + in relation to the glass transition temperature (Tg) of the polyamide resin.
It must be in the temperature range of 10 ° C. Refrigerant temperature is Tg-
When the temperature is lower than 30 ° C., there arises a problem of a temperature difference between the surface of the undrawn yarn and the inside or a problem such as generation of vacuum bubbles due to rapid cooling. If the temperature exceeds Tg + 10 ° C., problems such as crushing of the undrawn yarn due to insufficient cooling, or difficulty of drawing due to crystallization of the undrawn yarn occur. When using a material obtained by blending a plurality of resins as the polyamide resin,
In the present invention, Tg has a value defined by the following equation.

Tg (° C.) = A × TgA + b × TgB + c
× TgC + ... + n × TgN where a, b, c, ... N are A, B, C ,.
The volume fraction of each N component is shown, and TgA, Tg
B, TgC, ... TgN is A, B, C, ... N
The glass transition temperature (° C) of each component is shown. In the production method of the present invention, it becomes possible to produce a fiber having a high roundness by raising the temperature of the refrigerant higher than that in the case of conventional general spinning conditions, and a conventional cooling device for the refrigerant is required. Not.

A crystalline polyamide or a copolyamide obtained by polymerizing monomers containing metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component in an amount of 70 mol% or more, respectively, used in the production method of the present invention ( A) is the same as that contained in the stretched polyamide fiber of the present invention. As the single-screw or twin-screw extruder used for melting / spinning, various commonly used extruders can be arbitrarily used. The polyamide (A) and the other crystalline polyamide (B) used in the present invention are mixed by mixing solids such as pellets as they are and introducing them into an extruder, which is generally called dry blending. Alternatively, any of the methods generally called melt blending, in which solids are once melt-extruded and re-pelletized and used as a raw material, can be performed. Further, the present invention relates to a method for producing a stretched polyamide fiber stretched 2.5 to 8.0 times under the temperature condition of Tg or more and melting point or less of the polyamide.

The present invention relates to a stretched polyamide fiber having a circularity of 97 to 100% and a method for producing the same. Here, the circularity (%) is a value defined by the following equation, and as this value approaches 100%, the cross-sectional shape of the monofilament approaches a circular shape.

[0022]

Embedded image

[In the formula, RS _i represents the fiber minor axis (mm) at the i point in the n measurement sites, and RM _i represents the yarn diameter median value (mm) at the i point in the n measurement sites. ]

If the roundness of the fiber is less than 97%, the shape of the product after the secondary processing, for example, the multi-layer structure yarn such as the recent tennis gut, the woven cloth or the nonwoven cloth such as the filter cloth material for papermaking, is constant. It will cause the loss of product value. Further, there are problems that it is difficult to pass the fibers through the gaps or holes of the precisely processed article, and the compatibility with secondary processing equipment is low.

According to the present invention, as the stretched polyamide fiber, a fiber having a diameter after final stretching of 0.05 to 2 mm, preferably 0.1 to 1.5 mm can be produced.
Further, the polyamide resin used in the present invention, if necessary, a heat anti-aging agent, an anti-coloring agent, a cross-linking inhibitor, a weather resistance improver, an ultraviolet absorber, a pigment, an antistatic agent, a flame retardant or the like inorganic or The organic compounds may be used alone or in appropriate combination.

As the refrigerant used in the manufacturing method of the present invention, water, glycerin, liquid paraffin, silicone oil, hydrocarbon oil, polyethylene glycol, diethylene glycol or the like can be used.

[0027]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples. The strength and Young's modulus of the drawn yarn were measured according to JIS L 1013 “Test method for chemical fiber filament yarn”. Regarding the drawn yarn diameter measurement, the minor axis and the major axis at arbitrary points on the drawn yarn were measured at 100 points at 10 cm intervals. Table 1
In Examples 4 to 4, polyamide MXD6 is referred to as N-MXD6.

Example 1 Polyamide MXD6 (manufactured by Mitsubishi Gas Chemical Co., Inc., trade name:
6007) is melted using a single screw extruder and the spinning temperature is set to 2
Spin at a temperature of 60 ° C through a spinneret, and draft ratio is 1.
1. Under an air gap of 100 mm, the film was taken up in a water bath at a temperature of 70 ° C. and continuously drawn without being once wound. Stretching was carried out in two stages of stretching and one stage of heat setting. As a stretching means, a hot water bath at a temperature of 90 ° C was used in the first stage stretching region, a dry heat air bath of 220 ° C was used in the second stage stretching region, and a heat fixing region was used. A dry heat air bath of 280 ° C. was used, and the total stretching ratio was 5.
The draw ratio of 0 and 2 steps was 1.2, and the relaxation rate was 5%. The production speed was 48 m / min. Single fibers were obtained by the above method. Table 1 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 2 The same polyamide MXD6 as used in Example 1 was melted using a single-screw extruder, spun at a spinning temperature of 260 ° C. and spun through a spinneret, draft ratio 2.3, air gap 100 mm. Under a condition of a temperature of 90 ℃ in a water bath,
It was continuously stretched without being wound once. Stretch 2
As a stretching means, a hot water bath at a temperature of 90 ° C in the first stretching region, a dry heat air bath at 240 ° C in the second stretching region, and a dry heat at 280 ° C in the heat fixing region were used as stretching means. Using a hot air bath,
As the stretching conditions, the total stretching ratio was 5.2, the two-stage stretching ratio was 1.2, and the relaxation rate was 5%. Manufacturing speed is 75m / mi
n. Single fibers were obtained by the above method. Table 1 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 3 The same polyamide MXD6 and polyamide 6 as those used in Example 1 (manufactured by Ube Industries, Ltd., trade name: 1011F)
B) was melt-spun by dry blending at a weight ratio of 80/20, spun through a spinneret at a spinning temperature of 260 ° C., drawn into a water bath at a temperature of 70 ° C. under the conditions of a draft ratio of 2.3 and an air gap of 100 mm, and once It was continuously stretched without being wound up. A single fiber was obtained by the same method as in Example 2. Table 1 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 4 The same polyamide MXD6 and polyamide 6 as used in Example 3 were melted by dry blending in a weight ratio of 30/70, spun through a spinneret at a spinning temperature of 240 ° C., and a draft ratio of 2. 5. The film was taken up in a water bath at a temperature of 30 ° C. under the condition of an air gap of 100 mm and continuously drawn without being once wound. As the stretching conditions, the total stretching ratio was 5.1, the two-stage stretching ratio was 1.5, and the relaxation rate was 10%. The production speed was 78 m / min. Single fibers were obtained by the above method. Table 2 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 5 The same polyamide MXD6 and polyamide 6 as used in Example 3 were melted by dry blending in a weight ratio of 30/70, spun through a spinneret at a spinning temperature of 240 ° C., and a draft ratio of 2. 5. The film was taken up in a water bath at a temperature of 30 ° C. under the condition of an air gap of 10 mm and continuously drawn without being once wound. Single fibers were obtained in the same manner as in Example 4. Table 2 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 6 The same polyamide MXD6 and polyamide 6 as those used in Example 3 were melted by dry blending in a weight ratio of 20/80, spun through a spinneret at a spinning temperature of 240 ° C., and a draft ratio of 2. 7. The film was taken up in a water bath at a temperature of 30 ° C. under the condition of an air gap of 100 mm and continuously drawn without being once wound. Stretching was performed in the same manner as in Example 4 to obtain single fibers. Table 2 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 7 The same polyamide MXD6 and polyamide 66 as those used in Example 3 (manufactured by Ube Industries, Ltd., trade name: 2015)
B) is melted by dry blending in a weight ratio of 95/5,
Single fibers were obtained in the same manner as in Example 2. Table 3 shows the yarn diameter and roundness of the obtained polyamide fiber.

Example 8 The same polyamide MXD6 and polyamide 66 used in Example 7 were melted by dry blending in a weight ratio of 80/20, and a single fiber was obtained by the same method as in Example 3.
Table 3 shows the yarn diameter and roundness of the obtained polyamide fiber.

Comparative Example 1 The same polyamide MXD6 and polyamide 6 as used in Example 3 were melt blended in a weight ratio of 10/90 by dry blending using a single-screw extruder and the spinning temperature was set at 260 ° C. through a spinneret. The material was spun out, drawn into a water bath at a temperature of 6.5 ° C. under the conditions of a draft ratio of 2.7 and an air gap of 10 mm, and continuously drawn without being once wound. Stretching was performed in the same manner as in Example 4 to obtain single fibers. The yarn diameter and roundness of the obtained polyamide fiber are shown in Table 4.

Comparative Example 2 The same polyamide MXD6 and polyamide 6 as those used in Example 3 were melt blended in a weight ratio of 30/70 by dry blending using a single-screw extruder, and the spinning temperature was set at 260 ° C. through a spinneret. Spinning out, drawing in a water bath at a temperature of 5 ° C under the conditions of a draft rate of 2.5 and an air gap of 100 mm,
It was continuously stretched without being wound once. Stretching was performed in the same manner as in Example 4 to obtain single fibers. The yarn diameter and roundness of the obtained polyamide fiber are shown in Table 4.

Comparative Example 3 The same polyamide MXD6 and polyamide 6 used in Example 3 were melt blended in a weight ratio of 30/70 by dry blending using a single-screw extruder, and the spinning temperature was set at 260 ° C. through a spinneret. The material was spun out, drawn into a water bath at a temperature of 30 ° C. under the conditions of a draft rate of 4.0 and an air gap of 100 mm, and continuously drawn without being once wound. Stretching was performed in the same manner as in Example 4 to obtain single fibers. The yarn diameter and roundness of the obtained polyamide fiber are shown in Table 4.

Comparative Example 4 The same polyamide MXD6 and polyamide 66 used in Example 7 were melt blended in a weight ratio of 80/20 using a single-screw extruder and the spinning temperature was set to 260 ° C. through a spinneret. The material was spun out, drawn into a water bath at a temperature of 70 ° C. under the conditions of a draft rate of 4.0 and an air gap of 100 mm, and continuously drawn without being once wound. Stretching was performed in the same manner as in Example 2 to obtain single fibers. The yarn diameter and roundness of the obtained polyamide fiber are shown in Table 4.

[0040]

EFFECTS OF THE INVENTION The stretched polyamide fiber obtained by the present invention has a high strength and a high elastic modulus and exhibits a high roundness. Therefore, it can be used for sports goods such as a racket string, a rubber reinforcing material and a papermaking filter cloth material. It is useful for applications such as industrial materials.

[0041]

[Table 1] Example No. Example 1 Example 2 Example 3 Resin used N-MXD6 N-MXD6 N-MXD6 / N-6 Blend rate −−80 / 20 Tg (° C.) 85 85 77 Draft rate 1.1 2.3 2.4 Air gap (mm) 100 100 100 Refrigerant temperature (℃) 70 90 70 Stretching ratio 5.0 5.2 5.2 Stretched yarn diameter (mm) Minor axis minimum value 1.11 0.87 0.86 Major axis maximum value 1.13 0.90 0.87 Thread diameter median value 1.12 0.89 0.87 True circle Degree (%) 99.1 98.3 99.3 Young's modulus (kgf / mm ² ) 740 840 760 Tensile strength (gf / D) 6.2 6.0 6.0 Knot strength (gf / D) 4.1 4.4 4.5 Hooking strength (gf / D) 4.9 5.0 8.4

[0042]

[Table 2] Example number Example 4 Example 5 Example 6 Resin used N-MXD6 / N-6 N-MXD6 / N-6 N-MXD6 / N-6 Blend ratio 30/70 30/70 20 / 80 Tg (° C) 58 58 55 Draft rate 2.5 2.5 2.7 Air gap (mm) 100 10 100 Refrigerant temperature (° C) 30 30 30 Stretching ratio 5.1 5.1 5.1 Stretched yarn diameter (mm) Min. Minor axis value 0.43 0.42 0.47 Major axis maximum value 0.44 0.44 0.48 Median yarn diameter 0.44 0.43 0.48 Roundness (%) 98.4 97.7 99.2 Young's modulus (kgf / mm ² ) 540 540 450 Tensile strength (gf / D) 6.8 6.7 6.9 Knot strength (gf / D) 7.6 4.8 3.8 Hooking strength (gf / D) 10.7 5.8 5.8

[0043]

[Table 3] Example number Example 7 Example 8 Resin used N-MXD6 / N-66 N-MXD6 / N-66 Blend ratio 95/5 80/20 Tg (° C) 83 78 Draft ratio 2.3 2.3 Air gap (Mm) 100 100 Refrigerant temperature (℃) 90 70 Stretching ratio 5.2 5.2 Stretched yarn diameter (mm) Min. Minor axis 0.86 0.86 Max. Long diameter 0.88 0.87 Median yarn diameter 0.87 0.87 Roundness (%) 98.9 99.0 Young's modulus ( kgf / mm ² ) 760 710 Tensile strength (gf / D) 6.3 6.0 Knot strength (gf / D) 4.1 4.4 Hooking strength (gf / D) 5.0 7.2

[0044]

Table 4 Example No. Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Resin used N-MXD6 / N-6 N-MXD6 / N-6 N-MXD6 / N-6 N-MXD6 / N-66 Blend ratio 10/90 30/70 30/70 80/20 Tg (℃) 51 58 58 78 Draft ratio 2.7 2.5 4.0 4.0 Air gap (mm) 10 100 100 100 Refrigerant temperature (℃) 6.5 5 30 70 Stretch ratio 5.1 5.1 5.1 5.2 drawn yarn diameter (mm) short径最minimum value 0.42 0.44 0.38 0.80 major axis maximum value 0.44 0.53 0.46 0.96 yarn diameter median 0.43 0.48 0.42 0.88 roundness (%) 97.7 90.5 90.3 90.9 Young's modulus (kgf / mm ²⁾ 260 540 560 710 Tensile strength (gf / D) 7.4 7.5 6.2 6.3 Knot strength (gf / D) 3.8 4.6 3.3 3.5 Hooking strength (gf / D) 4.9 3.4 3.9 3.1

Claims (6)

[Claims] 1. Metaxylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component are each contained in 7 parts.
Crystalline polyamide or copolymerized polyamide (A) obtained by polymerizing a monomer containing 0 mol% or more of at least 20
% By weight, Young's modulus of 400 kgf / mm ² or more, pulling strength of 4.5 gf / D or more, knot strength of 3.5 g
A stretched polyamide fiber having a circularity of f / D or more and a circularity of 97 to 100%. 2. The stretched polyamide fiber according to claim 1, further comprising 80% by weight or less of a crystalline polyamide (B) other than the polyamide (A). 3. The stretched product according to claim 1, wherein the crystalline polyamide (B) is at least one selected from polyamide 6, polyamide 66 and a copolymer composed of a polyamide 6 component and a polyamide 66 component. Polyamide fiber. 4. Meta-xylylenediamine as a diamine component and adipic acid as a dicarboxylic acid component are each 7
Crystalline polyamide or copolymerized polyamide (A) obtained by polymerizing a monomer containing 0 mol% or more of at least 20
A polyamide resin containing wt% is melted using a single-screw or twin-screw extruder, spun through a spinneret, and taken up in a refrigerant bath located below the surface of the spinneret to obtain an unstretched yarn. A method for producing a stretched polyamide fiber that has been stretched 2.5 to 8.0 times under a temperature condition of a glass transition temperature (Tg) or higher and a melting point or lower, comprising: a spinneret cross-sectional area AD of a spinning machine; The ratio AD / AM to the cross-sectional area AM of the undrawn yarn obtained by cooling in the refrigerant bath after the spinning is 1.0 to 3.0, and the molten resin discharge port of the spinning machine and the cooling bath surface for cooling. The temperature (T) of the refrigerant bath for drawing the yarn extruded from the spinning machine is Tg-30.
A method for producing a stretched polyamide fiber having a range of ≦ T ≦ Tg + 10 ° C. 5. The polyamide resin containing at least 20% by weight of the polyamide (A) further contains 80% by weight or less of a crystalline polyamide (B) other than the polyamide (A). A method for producing the stretched polyamide fiber described. 6. The method for producing a stretched polyamide fiber according to claim 4, wherein the distance between the molten resin discharge port of the spinning machine and the cooling coolant bath surface is 10 to 150 mm.