JP2020158906A - High-strength polyamide monofilament - Google Patents

Abstract

To provide a polyamide monofilament having a fineness, a high strength, and small quality variation, and a method for producing the polyamide monofilament with high production efficiency.SOLUTION: There is provided a polyamide monofilament, in which a fineness is 8.0 to 30.0 dtex, a strength is 7.0 to 11.0 cN/dtex, and a strength variation (CV value) in the fiber longitudinal direction is less than 1.5%.SELECTED DRAWING: None

Description

The present invention relates to a high-strength polyamide monofilament and a method for producing the same.

Generally, polyamide monofilaments are limited to those having high strength or fineness, and there is no polyamide monofilament having both of these. Therefore, it has not been possible to provide high-quality polyamide monofilament for applications such as side threads of guts for rackets and sewing threads of stretch materials.

For example, one of the required characteristics of a gut is to make it finer (gauge is the thickness of the gut). By making the gauge thinner, it is possible to reduce the air resistance and gut weight during racket swing. On the other hand, in order to improve the response from collision with a gut such as a ball or shuttle to launch, it is required to stretch the gut on the racket with the highest possible tension, and it can withstand such high tension. A gut with high strength per unit cross-section is required. Therefore, fine gauge and high strength are required as the characteristics of the gut, and fineness and high strength are required for the core thread and side thread constituting the gut. As described above, the fineness and high strength are required. There has never been a polyamide monofilament that has both strength.

As a method for producing a high-strength polyamide monofilament, there is a method in which a polyamide resin is melt-spun and then water-cooled (Patent Documents 1, 2, and 3). Although the monofilament produced by this method has very high strength, only a monofilament having a high fineness that is not suitable as a side yarn of a gut can be formed due to the concern of thread breakage during water cooling. In addition, the production speed is slow and the production efficiency is low.

Further, in the method for producing a polyamide monofilament, there is also a method of cooling the yarn with cooling air after melt spinning (Patent Documents 4 and 5). Although it is possible to produce a polyamide monofilament having a fine fineness under a high production rate condition, the current technology has a maximum strength of about 6.0 cN / dtex, which does not satisfy sufficient strength.

Since a polyamide multifilament can withstand a high drawing tension, it becomes easy to obtain a high-strength filament by a manufacturing method using cooling air (Patent Documents 6 and 7), and a high-strength monofilament can be obtained by splitting the filament. be able to. However, due to the large drawing tension during multifilament reeling, the physical properties of each single fiber in the longitudinal direction vary. If it is used as a high-strength multifilament, this variation is not regarded as a problem in consideration of the application, but if each single fiber of the multifilament is split and used as a monofilament, if this variation is large, it will be the original. It greatly affects the quality of yarn and finished products.

Therefore, it is extremely difficult to produce a polyamide monofilament having a small fineness and high strength with high production efficiency by the conventional technique.

Japanese Unexamined Patent Publication No. 2000-279076 Japanese Unexamined Patent Publication No. 2011-101618 Japanese Unexamined Patent Publication No. 2005-204600 Japanese Unexamined Patent Publication No. 2008-57085 Japanese Unexamined Patent Publication No. 2009-108438 JP-A-2008-163494 Japanese Unexamined Patent Publication No. 2006-345924

An object of the present invention is to solve the above-mentioned problems, and to obtain a polyamide monofilament having high fineness and high strength and a small quality variation, and a method for producing the polyamide monofilament with high production efficiency. To provide.

In order to achieve the above object, the polyamide monofilament of the present invention has the following constitution.

That is, the fineness of the polyamide resin is 8.0 to 30.0 dtex, the breaking strength in the tensile test is 7.0 to 11.0 cN / dtex, and the strength variation CV value in the fiber longitudinal direction is less than 1.5%. It is a polyamide monofilament.

In the polyamide monofilament of the present invention, it is preferable that the main component of the polyamide resin is nylon 66 and the content ratio with respect to the total mass is 97% or more.
Further, the method for producing a polyamide monofilament of the present invention is characterized in that a polyamide resin is melt-spun and the yarns are cooled with cooling air to obtain a multifilament consisting of 8 to 16 yarns, and then the fibers are split. This is a method for producing a polyamide monofilament. In the method for producing a polyamide monofilament of the present invention, in the case of multifilament production, immediately after the polyamide resin is melt-spun, the yarn is passed through a high temperature atmosphere of -30 to + 30 ° C. with respect to the melting point of the polymer. It is preferable to do so.

According to the present invention, as will be described below, it is possible to provide a polyamide monofilament with low quality variation and high efficiency while having both fineness and high strength.

It is the schematic of the manufacturing process of the polyamide monofilament of this invention.

The polyamide monofilament of the present invention will be described below.

In order to achieve the above object, the polyamide monofilament of the present invention is made of a polyamide resin. As the polyamide resin, a polyamide resin whose main component is nylon 66 is preferable, and it is more preferable to use a polyamide resin in which 97% by mass or more of the total mass is composed of nylon 66, and more preferably it is composed of only nylon 66. Is. Nylon 66 and other polyamides can be copolymerized and used, and nylon 6, nylon 46, nylon 610, and nylon 612 can be used as the polyamide used for the copolymerization. By using nylon 66, which is a general-purpose polymer, not only can a monofilament be produced at low cost, but also a copper compound, a conventionally known inorganic and organic copper salt, and a simple substance of copper metal can be contained. In addition to the copper compound, the polyamide monofilament may contain other heat-resistant agents such as amine compounds, mercapto compounds, phosphorus compounds, and hindered phenol compounds. After performing the above copolymerization and addition of additives, by adding 97% by mass or more of nylon 66 component, not only high strength but also highly crystalline monofilament having excellent wear resistance can be obtained.

The relative viscosity of sulfuric acid of the polyamide monofilament is preferably 3.0 to 5.0, more preferably 3.5 to 4.5. If the relative viscosity of sulfuric acid is within the above range, it is possible to produce a high-strength monofilament having good spinnability. The relative viscosity of sulfuric acid refers to a value measured by the method described in the column of Examples.

The polyamide monofilament of the present invention has a fineness (single fiber fineness) of 8.0 to 30.0 dtex. The fineness is preferably in the range of 8.0 to 20.0 dtex, more preferably in the range of 9.0 to 15.0 dtex. If the fineness is less than 8 dtex, the fineness is too fine, and there is a high possibility that fluff will be generated during thermal drawing of the multifilament after melt spinning. The fluff in the multifilament means the yarn breakage of the filament (single fiber) constituting the multifilament, and when the fluffy multifilament is split, the yarn breakage occurs in the process. Further, when the fineness exceeds 30 dtex, for example, it becomes difficult to use the gut as a side yarn, and the uniform cooling property at the time of spinning deteriorates, so that the quality of the raw yarn deteriorates, and the gut is strong and durable. Will decrease.

The strength of the polyamide monofilament of the present invention is 6.5 to 11.0 cN / dtex. More preferably, it is 7.5 to 11.0 cN / dtex. The strength of the polyamide monofilament generally used for gut is about 6.5 cN / dtex, and there has never been a polyamide monofilament for gut having a strength exceeding 7.5 cN / dtex, and 7.5 cN / dtex as in the present invention. By arranging a polyamide monofilament of dtex or more on the side yarn, it is possible to obtain a gut having high strength per unit cross-sectional area and improved durability. When the strength is less than 6.5 cN / dtex, it becomes difficult to obtain a gut having high strength and high durability per unit cross-section. The strength refers to a value measured by the method described in the column of Examples.

It is essential that the strength variation of the polyamide monofilament of the present invention is less than 1.5% in terms of CV value. When the CV value is 1.5% or more, the portion having weak strength is easily broken, which leads to impairing the durability of the gut using the monofilament as the side thread. The strength variation CV value refers to a value measured by the method described in the column of Examples.

The breaking elongation of the polyamide monofilament of the present invention is preferably 15 to 30%, more preferably 21 to 30%. Within such a range, durability can be maintained even at low temperatures. The elongation refers to the value measured by the method described in the column of Examples.

The cross-sectional shape is not particularly limited. Including a round cross section, a cross section having various shapes such as flat, polygonal, and Y-shaped can be adopted.

The method for producing the polyamide monofilament of the present invention will be described below.

The polyamide monofilament of the present invention is obtained by melt-spinning nylon 66 resin, solidifying it with cooling air, applying an oil agent, and splitting the multifilament obtained by stretching the yarn between rollers. ..

The polyamide monofilament of the present invention is preferably obtained by splitting a multifilament composed of 8 to 16 single fibers, and more preferably 12 to 16 single fibers (number of filaments). If it is less than eight, not only the number of monofilaments obtained from one multifilament is reduced, but also the single fiber fineness when the total fineness of the multifilament is constant becomes thick, as described above. It becomes impossible to obtain the monofilament of the quality required for. On the other hand, the number of bobbins that can be defibrated and wound by a general defibrator is 16, and if a multifilament having a larger number of single fibers is to be defibrated, the number of defibrations is required to be 2 or more. Since the cold stretching of the fiber is caused in the fiber splitting step, the strong elongation product is lowered, and the strong elongation product is greatly lowered by the fiber splitting twice or more.

The method for producing the polyamide multifilament before fiber separation will be described below.

The relative viscosity of sulfuric acid of the nylon 66 resin used for melt spinning is preferably 3.0 to 5.0, more preferably 3.5 to 4.5. Within such a range, a high-strength nylon 66 monofilament can be obtained more stably with good spinnability.
FIG. 1 shows an outline of one aspect of a method for producing a polyamide multifilament before fiber splitting.

The above polyamide resin is melted and kneaded with an extruder type spinning machine, and the spinning temperature is set to a value 50 ° C. higher than the melting point of the polymer, and melted from a base 1 having a plurality of holes, preferably 8 to 16. Spinning is performed, but it is a preferable form to surround a range of 5 to 300 cm from directly below the spinneret with a heating cylinder 2 and allow the spun yarn to pass through a high temperature atmosphere of -30 to + 30 ° C. with respect to the melting point, which is more preferable. Is -15 to + 15 ° C. By slowly cooling the spun yarn through a high-temperature atmosphere surrounded by the heating cylinder without immediately cooling the spun yarn, the orientation of the melt-spun nylon 66 molecules is relaxed, and the molecular orientation uniformity between the single fibers is enhanced. Therefore, the strength of the nylon 66 filament can be increased. On the other hand, if the yarn is cooled immediately without passing through the high temperature atmosphere, the orientation of the undrawn yarn is increased and the degree of orientation variation between the single fibers is increased. When such undrawn yarn is thermally drawn, a high-strength nylon 66 filament may not be obtained as a result. Further, if the temperature of the high temperature atmosphere created by the heating cylinder exceeds 280 ° C., the yarn sway during cooling after melt spinning becomes large, and the fineness variation of the monofilament becomes worse due to this.

The undrawn threads that have passed through the high temperature atmosphere are then cooled and solidified by blowing air at 10 to 80 ° C., preferably 10 to 50 ° C. by the cross-flow cooling device 3. If the cooling air is less than 10 ° C., a large cooling device is required, which is not preferable. Further, when the cooling air exceeds 100 ° C., the single fiber sway during spinning becomes large, so that the single fibers collide with each other and cause deterioration of the spinning property.
The undrawn yarn is preferably multi-stage drawn, particularly preferably two-stage drawn. To give a concrete example of the case of two-stage drawing, first, an oil agent is applied to the cooled and solidified undrawn yarn by the oil supply device 4, and the undrawn yarn is taken up by a take-up roller (1FR). After that, the yarns are wound in the order of the yarn feeding roller (2FR), the first stretching roller (1DR), the second stretching roller (2DR), and the relaxation roller (RR) to perform heat treatment and stretching treatment, and then wound around the winder 11. take. The surface of 2FR is preferably a mirror surface, and the surfaces of 1DR, 2DR, and RR are preferably satin finished.

The first step of stretching is performed between 2FR and 1DR, and the temperature of 2FR is 30 to 50 ° C. and the temperature of 1DR is 100 to 225 ° C.

The second stage stretching is performed between 1DR and 2DR, and the temperature of 2DR is preferably 218 to 228 ° C. In the second-stage drawing, the yarn that has become a drawn yarn with a high degree of orientation in the first-stage drawing is further thermally drawn, so that a large drawing tension is applied to the yarn and the quality can be maintained in the fiber longitudinal direction. difficult. However, quality variation can be suppressed by performing thermal stretching under appropriate temperature conditions. If the temperature of the 2DR is less than 215 ° C., the drawing tension due to the 2DR becomes higher than necessary, resulting in quality variation in the fiber longitudinal direction. Further, when the temperature is higher than 228 ° C., the stretching tension is low and the stretching speed on the DR varies, so that the quality also varies in this case as well.

Thus, the polyamide multifilament for obtaining the polyamide monofilament of the present invention can be obtained.

By splitting the obtained polyamide multifilament with a fiber separator, a polyamide monofilament is obtained. A known fiber-dividing machine can be used for fiber-dividing, and the production (fiber-dividing) rate of monofilament is preferably 100 to 1000 m / min, more preferably 300 to 700 m / min. By splitting in this speed range, monofilaments can be efficiently obtained without causing a decrease in the strong elongation product due to cold stretching as much as possible.

[Relative viscosity]
1 g of the sample was dissolved in 100 ml of 98% sulfuric acid and measured at 25 ° C. using an Ostwald viscometer. The average value of 2 times was used.

[Multifilament fineness]
It was measured according to JIS L1090 (1999).

[Monofilament fineness]:
Measurement was performed using a VIBROSKOP500 manufactured by INTEC Inc. and 700 mg as a tension weight.

[Fiber strength and elongation]
The tensile strength and elongation measured by the method of JIS L1013 (1999) were defined as strength and elongation. The measurement was performed using a Tensilon tensile tester manufactured by Orientec Co., Ltd. under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min. The measurement was performed three times for each sample, and the average value was calculated.

[Strength variation in the fiber longitudinal direction (CV value)]
The tensile strength measured by the method of JIS L1013 (1999) was taken as the strength. The measurement was performed using a Tensilon tensile tester manufactured by Orientec Co., Ltd. under the conditions of a test length of 250 mm and a tensile speed of 300 mm / min. Each sample was measured 5 times every 1 m in the longitudinal direction of the fiber, and the average value and standard deviation were used to calculate by the following formula.
[CV value] (%) = [standard deviation] / [mean value] × 100.

[Passability of fiber separation process]
The evaluation was made in the following three stages from the state of thread breakage when a 200,000 m multifilament was separated at 400 m / min with a fiber separator.

◯: Thread breakage is less than 0.2 times / hour, stable production is possible Δ: Thread breakage is 0.2 to 1.0 times / hour ×: Thread breakage is 1.0 times / hour or more ..

[Production efficiency]
It was evaluated in the following three stages from the production rate of monofilament.

◯: Production of monofilament of 5000 m or more per minute is possible Δ: Production of monofilament of 1000 to 5000 m per minute is possible ×: Less than 1000 m per minute or thread breakage occurs frequently in the silk reeling or fiber splitting process, and production is impossible.

(Example 1)
(Manufacturing method of polyamide multifilament)
Nylon 66 polymer having a relative sulfuric acid viscosity of 3.8 was melt-spun at 285 ° C. using an extruder type spinning machine. The molten polymer was weighed with a gear pump so that the total fineness was 175 dtex, filtered through a 20 μ metal non-woven fabric filter in a spinning pack, and spun from a 16-hole base. A heating cylinder having a heating cylinder length of 15 cm was installed 3 cm below the base surface, and the temperature inside the cylinder was heated to 250 ° C. Here, the in-cylinder atmospheric temperature is the air temperature at the central portion of the length of the heating cylinder, which is 1 cm away from the inner wall.

A uniflow type chimney that blows air from one direction was attached directly under the heating cylinder, and cold air at 20 ° C. was blown onto the threads at a speed of 40 m / min to cool and solidify, and then an oil agent was applied to the threads.

The undrawn threads to which the oil agent was applied were wound around 1FR rotating at a surface speed of 850 m / min and taken up, and then drawn at a total draw ratio of 4.10 times. The take-up thread is continuously stretched by 5% between the take-up roller and 2FR without being wound once, and then the first step is stretched at a rotation speed ratio of 2.60 times, and then the rotation speed. The second step was stretched at a ratio of 1.50 times, and the film was wound at a speed of 3400 m / min. The roller surface of 1FR and 2FR is mirror-finished, 1DR, 2DR, and RR are satin-finished, and the roller temperature is 1FR unheated, 2FR 40 ° C, 1DR 150 ° C, and 2DR 225 ° C. Was set to 150 ° C. Nylon 66 multifilament was obtained by such melt spinning and stretching. The physical properties of the obtained fibers were evaluated and shown in Table 1.

(Manufacturing method of polyamide monofilament)
A multifilament composed of 16 single fibers was split, wound around 16 bobbins, unwound and split at a speed of 400 m / min to obtain a monofilament. The physical properties of the fibers were evaluated and shown in Table 1.

(Example 2)
The same procedure as in Example 1 was carried out except that the total draw ratio was set to 3.4 times when the nylon 66 multifilament was spun.

(Example 3)
The procedure was the same as in Example 1 except that the number of single fibers of the nylon 66 multifilament was 12 (the total fineness was the same), the winding speed was 2500 m / min, and the total draw ratio was 4.0 times.

(Example 4)
Same as in Example 1 except that a mixture of 95% by mass of nylon 66 polymer having a relative sulfuric acid viscosity of 3.80 and 5% by mass of nylon 6 polymer having a relative sulfuric acid viscosity of 3.80 was melt-spun. went.

(Example 5)
Same as in Example 1 except that a mixture of 95% by mass of nylon 66 polymer having a relative sulfuric acid viscosity of 3.80 and 5% by mass of nylon 6 polymer having a relative sulfuric acid viscosity of 3.21 was melt-spun. went.

(Comparative Example 1)
This was carried out in the same manner as in Example 1 except that the temperature of 2DR was set to 235 ° C.

(Comparative Example 2)
This was carried out in the same manner as in Example 2 except that the temperature of 2DR was set to 235 ° C.

(Comparative Example 3)
The same procedure as in Example 3 was carried out except that the temperature of 2DR was set to 235 ° C.

(Comparative Example 4)
The same procedure as in Example 3 was carried out except that the temperature of 2DR was set to 215 ° C.

(Comparative Example 5)
The same procedure as in Example 1 was carried out except that the molten polymer was weighed with a gear pump so that the fineness was 120 dtex during melt spinning.

(Comparative Example 6)
A polyamide monofilament was obtained by carrying out as described in Example 4 of Patent Document 4.

(Comparative Example 7)
A polyamide monofilament was obtained by carrying out as described in Example 1 of Patent Document 5.

(Reference example 1)
A polyamide monofilament was obtained by carrying out as described in Example 1 of Patent Document 1.

(Reference example 2)
A polyamide monofilament was obtained by carrying out as described in Example 1 of Patent Document 2.

Table 1 shows the results of evaluating the physical properties of the polyamide monofilaments obtained in Examples 1 to 5 and Comparative Examples 1 to 7.

As is clear from Table 1, the polyamide monofilament of the present invention can be produced with high productivity.

On the other hand, although the monofilaments of Reference Examples 1 and 2 which are the prior arts have high strength, they have a high fineness and cannot be used as a covering yarn for gut.

Further, as in Comparative Example 6 or Comparative Example 7, it has been difficult to obtain a high-strength monofilament by the prior art even in the fineness range that can be used as a covering yarn.

Further, as in Comparative Examples 1 to 4, when producing a high-strength monofilament, the strength in the longitudinal direction of the fiber tends to vary due to the high drawing tension, while in Comparative Example 5, the fineness is small. Thread breakage occurred in the fiber process.

The gut using the polyamide monofilament of the present invention has an advantage that it can be made into a fine gauge because of its high strength per unit cross section, and can be attached to a racket with high tension. Therefore, as strings for advanced users, it can be suitably used for rackets such as tennis, squash, and badminton. Further, by combining a monofilament having a high strength and a high elongation, a durable multifilament having a high elongation product can be obtained, so that it can be used as a sewing thread for a stretch material or the like.

1: Spinning cap 2: Heating cylinder 3: Cross flow cooling device 4: Refueling device 5: Thread 6: Take-up roller (1FR)
7: Thread feeding roller (2FR)
8: First stretching roller (1DR)
9: Second stretching roller (2DR)
10: Relaxing roller (RR)
11: Winder

Claims (5)

Polyamide made of a polyamide resin, characterized in that the fineness is 8.0 to 30.0 dtex, the strength is 7.0 to 11.0 cN / dtex, and the strength variation (CV value) in the fiber longitudinal direction is less than 1.5%. Monofilament. The polyamide monofilament according to claim 1, wherein the main component of the polyamide resin is nylon 66. The polyamide monofilament according to claim 1 or 2, wherein the mass% of nylon 66 in the polyamide resin is 97% or more. A method for producing a polyamide monofilament, which comprises melt-spinning a polyamide resin and cooling the yarn with cooling air to obtain a multifilament consisting of 8 to 16 yarns and then splitting the yarn. The production of the polyamide monofilament according to claim 4, wherein in the production of the multifilament, the yarn is passed through a high temperature atmosphere of -30 to + 30 ° C. with respect to the melting point of the polymer immediately after the polyamide resin is melt-spun. Method.