JP2000154472A - Polycaproamide fiber having good fatigue resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyamide fiber having a high strength, and an excellent strength-retaining characteristics and fatigue resistance, and suitable to a rubber- reinforcing usage. SOLUTION: This polyamide fiber which substantially consists of polycapramide containing 0.05-0.5 wt.% one or more kinds of potassium salts selected from potassium iodide, potassium bromide and potassium chloride, 0.01-0.1 wt.% one or more kinds of copper salts selected from cuprous iodide and cuprous chloride, and 0.1-0.5 wt.% 2-mercaptobenzimidazole has a nonaqueous oil solution containing 15-25 wt.% polyester comprising the ethylene oxide adduct of a castor oil, and sebacic acid and/or stearic acid, and having 5,000-7,000 molecular weight, based on the oil solution component, imparted to the surface of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycapramide fiber which has high strength and excellent fatigue resistance, is suitable for reinforcing rubber, and has good tire fatigue resistance when formed into a tire cord. .

[0002]

2. Description of the Related Art Polyamide fibers have been used for industrial materials for rubber reinforcement because of their excellent toughness, adhesiveness and fatigue resistance.

[0003] When a polyamide fiber is used as a rubber reinforcing cord, a strong holding property against thermal and mechanical damages received in a twisting step, a heat setting step after applying an adhesive, a rubber vulcanization step, and the like, and a tire Performance such as fatigue resistance against repeated fatigue during running is strongly required, and many studies have been made conventionally.

[0004] Therefore, there has been proposed a polyamide fiber provided with an aqueous emulsion oil before melt spinning and winding. With such a fiber, the twisting process, the heat setting process after applying the adhesive, the strong retention against thermal and mechanical damage received in the rubber vulcanizing process, and the fatigue resistance against repeated fatigue during tire running, etc. Performance is improved. However, when the water-based oil agent is used, the stretchability is deteriorated, and the raw yarn strength is less than 10 g / d, and it is difficult to increase the strength.

When a non-aqueous oil is used in consideration of stretchability,
Although a high-strength fiber having a yarn strength of 10 g / d or more can be obtained, the performance such as the strength retention property against thermal and mechanical damage and the fatigue resistance property against repeated fatigue tends to decrease.
Tire cords with satisfactory performance have not been obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides a polyamide fiber which is high in strength and has excellent holding properties and fatigue resistance and which is suitable for rubber reinforcing applications. It is a technical issue to provide.

[0007]

Means for Solving the Problems The present inventors have studied to achieve the above object, and as a result, have reached the present invention. That is, 0.05 to 0.5% by weight of one or more potassium salts selected from potassium iodide, potassium bromide and potassium chloride, and one or more potassium salts selected from cuprous iodide and cuprous chloride A fiber substantially consisting of polycapramide containing 0.01 to 0.1% by weight of a copper salt of 0.1% to 0.5% by weight of 2-mercaptobenzimidazole, and an ethylene oxide adduct of castor oil Fatigue resistance characterized in that a non-aqueous oil agent containing 15 to 25% by weight of a polyester having a molecular weight of 5,000 to 7000 comprising sebacic acid and / or stearic acid with respect to the oil agent component is applied to the fiber surface. Is a gist of a good polycapramide fiber.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The polycapramide fiber of the present invention has ε-capramide as a repeating structural unit of a molecular chain, and among them, a repeating structural unit having a repeating structural unit of 95 mol% or more is preferable. And, as the copolymerization component, for example, polyhexamethylene adipamide, polyhexamethylene sebacamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, or the like may be contained.

[0009] The fiber of the present invention contains at least one potassium salt selected from potassium iodide, potassium bromide and potassium chloride as a heat-resistant agent and an antioxidant in an amount of 0.05 to 0.1%.
5% by weight, 0.01 to 0.1% by weight of one or more copper salts selected from cuprous iodide and cuprous chloride, and 0.1 to 0.5% of 2-mercaptobenzimidazole. % By weight.

These can be mixed and contained in chips after the polycapramide polymerization step or chip formation. In order to mix and contain the chips, the chips are dry-blended with polycapramid chips and supplied to a spinning machine, or made into master chips in advance and chip-blended and supplied to a spinning machine.

When the contents of these potassium salts, copper salts, and 2-mercaptobenzimidazole are less than the above ranges, the heat resistance and fatigue resistance of the fibers deteriorate. On the other hand, when the content exceeds the above range, the effect of improving heat resistance and fatigue resistance is not only saturated, but also the drawability is adversely affected, and the quality and physical properties of the obtained fiber are reduced.

Further, the polycapramide fiber of the present invention comprises
Polyester comprising an ethylene oxide adduct of castor oil and sebacic acid, and a polyester comprising an ethylene oxide adduct of castor oil, sebacic acid and stearic acid, having a molecular weight of 5,000 to 7000 to 15 to 25 with respect to the oil component. A non-aqueous oil agent containing about 10% by weight is applied to the fiber surface.

The polyester component in the oil agent functions as an extreme pressure lubricant and has a molecular weight of 5,000 to 70.
By setting the value to 00, the friction between the filaments is reduced, and when the cord is used for rubber reinforcement, heat generation in the tire is suppressed, and the fatigue resistance of the tire is improved.

If the amount of the polyester component is less than 15% by weight or the molecular weight is less than 5,000, such effects of heat resistance and antistatic properties are not sufficiently exhibited, and tire fatigue resistance is improved. Can not do. On the other hand, if the amount of the polyester component exceeds 25% by weight or the molecular weight is
When it exceeds 00, the stability over time of the polyester component is deteriorated, and the heat resistance and the antistatic property are not improved.

The position where such a non-aqueous oil agent is applied is as follows:
After the filament spun by a normal melt spinning device is cooled and solidified, it may be in any position until it is wound up, but after the spun filament is solidified,
It is preferable to apply it before stretching. Also,
It is preferable that this non-aqueous oil is diluted with a low-viscosity mineral oil to a concentration of 20 to 40% by weight before use.

It is preferred that the amount of the oil agent (the amount of the undiluted pure component) be 0.5 to 2.0% by weight based on the weight of the yarn.
If it is less than 5% by weight, the fatigue resistance is hardly improved, and if it exceeds 2.0% by weight, the adhesiveness to rubber tends to be deteriorated when it is used as a dip cord.

The fiber of the present invention contains the above-mentioned heat-resistant agent and antioxidant, and has a fatigue resistance of 2050 minutes or more due to the addition of a specific oil agent. I have. The tube fatigue strength referred to here is J
According to IS L1017 2.2.1, it was measured with 24 dip cords / 2.54 cm and a tube length of 23.4 cm.

The fiber of the present invention has a tube fatigue strength of 20.
50 minutes or more, and generally has a strength of 10 g / d or more,
By being less than 4%, the tire strength (JI
SD4230 5.1) measured on drum running 20
It is 20,000 kgf / cm or more at 000 km.

[0019]

Next, the present invention will be specifically described with reference to examples. The measurements and evaluations of various values in the examples were performed as follows. (1) Relative viscosity of sulfuric acid (ηrel) 0.5 g of a sample was dissolved in 50 cc of 96% sulfuric acid and measured at 25 ° C. using an Ubbelohde viscometer. (2) Strength and elongation of yarn: 25 times / time using Shimadzu Autograph S-100.
The measurement was performed at a tensile speed of 30 cm / min and a chart speed of 30 cm / min for a sample of a 25 cm raw yarn to which a twist of m was added. (3) Strength and elongation of cord ・ Dip cord The obtained fiber is twisted 32 times per 10 cm, and then the two twisted cords are combined to form the same number of twists in the opposite direction to the twist. The raw code was applied. Then, an adhesive application process was performed on each raw cord by a dipping machine manufactured by Ritzler. The sample was immersed in the RFL solution, and the solution concentration and the draining device were adjusted so that the amount of adhesion was 5% by weight.
The drying zone was passed at 120 ° C. for 144 seconds with a tension of 0.60 g / d, and the heat treatment zone was heated at 200 ° C. for 60 seconds.
1. Passed at a tension of 10 g / d, the normal zone was 2
Dip cords were obtained by passing at 00 ° C. for 36 seconds at a tension of 0.76 g / d. This cord was measured using an Autograph S-100 manufactured by Shimadzu Corporation at a sample length of 25 cm, a tensile speed of 30 cm / min, and a chart speed of 30 cm / min. Vulcanized cords Dip cords are arranged in parallel at a density of 24 / inch under no load, sandwiched between 8.5 mm thick uncured rubber sheets, and placed in a mold and maintained at 165 ° C. The mixture was vulcanized and bonded by a heat press for 15 minutes. After vulcanization, the mold was taken out of the heat press and cooled with water, and the test piece was taken out of the mold at room temperature. After standing for 24 hours, the cord was peeled off and used as a vulcanized cord. Using an autograph S-100 manufactured by Shimadzu Corporation, the sample length was 25 cm and the tensile speed was 3
The measurement was performed at 0 cm / min and at a chart speed of 30 cm / min. (4) Tube Fatigue Strength A dip cord was prepared as described above, and the fatigue strength was measured by the method described above. (5) Tire strength (breaking energy) Measured by the method described above. (6) Tire heating temperature In the measurement of (5), the surface temperature of the tire at the time of traveling 7000 km was measured using a radiation thermometer THI-50 manufactured by Taxco Japan.
It measured using 0.

Example 1, Comparative Examples 1-2 Polycapramide having a relative viscosity of 3.52 sulfuric acid and a water content of 0.08% was mixed with 0.1% by weight of potassium iodide and 0.04% of cuprous iodide.
A dry blend of 0.3% by weight of 2-mercaptobenzimidazole and 0.3% by weight of 2-mercaptobenzimidazole was supplied to an ordinary melt spinning apparatus, and was melted at a spinning temperature of 280 ° C. and spun through a die. Before taking the cooled and solidified yarn with the first roller, see Table 1.
As shown in Table 2, oil compositions having various compositions were provided. At this time, the oil was applied so as to have an adhesion amount (pure content) of 1% by weight with respect to the yarn weight, and the oil agent was diluted with a mineral oil to a concentration of 30% by weight and used. Thereafter, the film is stretched in the first stage at a stretch ratio of 3.20 times with a first roller (130 ° C.) without winding, and a high-pressure steam treatment device is provided between the first roller and a second roller (190 ° C.). 370 ° C, magnification 1.7
The film was stretched by a factor of 2 and taken up at a second roller speed of 2500 m / min. Subsequently, a relaxation process is performed between the second roller and the third roller (180 ° C.) at a relaxation rate of 9.8% to perform 1780 d
/ 316f fiber was obtained. Table 2 shows the results obtained by measuring the strength, strength, elongation, tube fatigue strength, and tire strength of the obtained fiber and the dip cord and the vulcanized cord obtained using the fiber.

[0021]

[Table 1]

[0022]

[Table 2]

As apparent from Table 2, the fiber of Example 1 has a high tube fatigue strength of 2050 minutes or more, and the tire has a fatigue resistance of 20,000 km at 20,000 km running on the drum.
It was as high as 000 kgf / cm or more, and was suitable for rubber reinforcement applications. On the other hand, since the fiber of Comparative Example 1 was provided with an oil agent having a polyester molecular weight exceeding 7000, the fiber of Comparative Example 2 had a polyester molecular weight of 500.
Since less than 0 oil agent was applied, both the tube fatigue strength and the fatigue resistance of the tire were low. In particular, the fiber of Comparative Example 2 burst when the tire was run at 12,000 km.

Examples 2-5, Comparative Examples 3-4 Potassium iodide, cuprous iodide added to polycapramide,
Example 1 was repeated except that the amounts of 2-mercaptobenzimidazole, potassium bromide and potassium chloride were variously changed as shown in Table 3. Table 4 shows the results of measuring the strength, strength, elongation, tube fatigue strength, tire strength, and tire heating temperature of the obtained fiber and the dip cord and the vulcanized cord obtained using the fiber.

[0025]

[Table 3]

[0026]

[Table 4]

As is clear from Table 4, the fibers of Examples 2 to 5 have a high tube fatigue strength of at least 2050 minutes, and also have a high tire fatigue resistance of 20,000 kgf / cm or more when the drum runs at 20,000 km. It was suitable for rubber reinforcement applications. On the other hand, the fiber of Comparative Example 3 had too low a content of potassium salt, so that the heat resistance and the fatigue resistance of the fiber deteriorated, the tube fatigue strength and the tire fatigue resistance were both low, and the tire was 15,000 km. It burst when I drove. The fiber of Comparative Example 4 had an excessively large content of potassium salt, so that the drawability was adversely affected, and both the tube fatigue strength and the tire fatigue resistance were low.

[0028]

The polycapramide fiber of the present invention contains an appropriate amount of a specific compound as a heat-resistant agent and an antioxidant, so that the strength retention of a dip cord or a vulcanized cord is improved, By providing an oil agent containing polyester that acts as a pressure lubricant, friction between filaments is reduced, heat generation during repeated fatigue can be suppressed, and wear can be reduced, so tire cords Then, a tire having high strength and excellent fatigue resistance can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C08L 77/02 C08L 77/02 D06M 101: 34 (72) Inventor Masaki Oku Ujitonouchi, Uji City, Kyoto Prefecture 5 Unitika Fuji term in the Uji factory (reference) 4J002 AE053 CF002 CL011 GN01 4L033 AA08 AB01 AC11 AC15 BA01 BA08 BA16 CA45 DA02 4L035 BB31 BB36 BB60 BB61 BB77 BB89 BB91 CC02 CC07 EE01 EJ09 EJ21 EJ01 EJ09 EJ20 EE01 EJ09 EJ20 EE01 EE01 EE20 EE01 EE09 EE20 EE01 EJ09 EJ10 EJ01 EJ20 EE01 EJ01 EJ20 EJ01 EJ01 EJ09 EJ01 PA03 PA26 UA06 UA08

Claims (1)

[Claims] 1. The method according to claim 1, wherein at least one kind of potassium salt selected from potassium iodide, potassium bromide and potassium chloride is used in an amount of 0.05 to
0.5% by weight, 1 selected from cuprous iodide and cuprous chloride
A fiber substantially consisting of polycapramide containing 0.01 to 0.1% by weight of at least one kind of copper salt and 0.1 to 0.5% by weight of 2-mercaptobenzimidazole, wherein ethylene oxide of castor oil is used. A non-aqueous oil agent containing 15 to 25% by weight, based on the oil agent component, of a polyester having a molecular weight of 5,000 to 7000 comprising an adduct and sebacic acid and / or stearic acid is applied to the fiber surface. Polycapramid fiber with good fatigue properties.