JP2566993B2 - Polyhexamethylene adipamide multifilament yarn with good fatigue resistance - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyhexamethylene adipamide multifilament yarn having good fatigue resistance, which is used as an industrial material such as a tire cord and a belt for rubber reinforcement.

[Conventional technology]

Polyhexamethylene adipamide fiber is widely used as a fiber for tire cord because of its excellent strength, heat resistance, fatigue resistance, adhesion to rubber and the like.

However, it is necessary to improve the durability of the tire from the viewpoint of improving the safety as well as the economic effect of extending the life of the tire, and the tire cord that reinforces the tire is required to improve the fatigue resistance. ing.

As a method for improving the fatigue resistance of polyhexamethylene adipamide fiber, Japanese Patent Publication No. 60-22084 discloses a method of winding at 2000 m / min or more and hot drawing at 3.5 times or less. It is described that this method makes the fiber have a clear two-layer structure, and that the low degree of amorphous orientation contributes to high fatigue resistance. This method seeks to improve fatigue resistance by changing the microstructure of the fiber.

However, this method has a problem that the fatigue resistance is improved, but the strength required for industrial materials such as tire cords is not sufficiently developed.

[Problems to be solved by the invention]

An object of the present invention is to provide a polyhexamethylene adipamide multifilament yarn for industrial materials, which has sufficient strength and has improved fatigue resistance.

The fibers in the tire are subjected to repeated stress of compression and extension to be fatigue-deteriorated, the strength of the fibers is lowered, and the fibers are broken. The present inventor has conducted diligent research in order to extend the time until the fracture, that is, to improve the fatigue resistance. And
When the behavior of the fibers in the tire was examined, it was found that one of the major causes of the decrease in the strength of the fibers was that the repeated stress was concentrated on a specific single fiber. Therefore,
The present invention has been accomplished in consideration of producing fibers in which this repeated stress is uniformly applied to each single fiber.

[Means for solving problems]

A finishing agent containing 5 to 30% by weight of a complex ester having a number average molecular weight of 5000 or more obtained from a polyhydric alcohol ethylene oxide adduct and a monocarboxylic acid or a dicarboxylic acid is added to the fiber in an amount of 0.5 to 2.0% by weight. , Thread-thread friction coefficient μ
_The polyamide multifilament yarn for industrial materials is characterized in that s satisfies the following expression (1) μ _s ≦ 0.22 (1).

The polyhexamethylene adipamide used in the present invention is mainly composed of a repeating unit represented by the following formula.

-CO (CH ₂₎ modified polyhexamethylene adipamide containing ₄ CONH (CH ₂₎ a ₆ NH- other amide units 10 wt% or less can also be used in the present invention. As such a monomer forming a small amount of amide units,
Aliphatic dicarboxylic acids such as sebacic acid and dodecanoic acid; aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; aliphatic diamines such as decamethylenediamine; aromatic diamines such as metaxylylenediamine; and ω such as ε-aminocaproic acid -The amino acids caprolactam, laurinlactam and the like can be used. It is also possible to use a mixture of the above polyhexamethylene adipamide with 20% by weight or less of a polyamide such as polycapramide and polyhexamethylene sebacamide.

Furthermore, the polyhexamethylene adipamide is an additive usually used for polyamides, such as copper acetate,
Copper chloride, copper iodide, heat stabilizers such as mercaptobenzimidazole, manganese lactate, light stabilizers such as manganese hypophosphite, phosphoric acid, phenylphosphonic acid, thickeners such as sodium pyrophosphate, titanium dioxide, It may contain a matting agent such as silicon dioxide and kaolin, a lubricant such as methylenebisstearylamide and calcium stearate, and a plasticizer.

The polyhexamethylene adipamide multifilament yarn of the present invention has a yarn-yarn friction coefficient μs of 0.22 or less, preferably 0.20 or less.

As described above, by reducing the yarn-yarn friction, the movement of the single yarn in the dip cord in the rubber becomes smooth, and thus the stress is less likely to be concentrated on the specific single yarn. It is considered that this improves fatigue resistance.

The multifilament yarn for tire cords currently on the market has a yarn-yarn friction coefficient μs of 0.24 to 0.26 or more. When the yarn-yarn friction coefficient μs is larger than 0.22, stress is likely to be concentrated on the specific single yarn, resulting in low fatigue resistance.

On the other hand, if the yarn-yarn friction coefficient μs is 0.22 or less, stress concentration on a specific single yarn is unlikely to occur and fatigue resistance is improved.
Further, when it is 0.20 or less, the effect is remarkable.

This can be inferred from the relationship between the stress acting on the dip cord in the rubber and the frictional force. That is, a certain amount of stress acts on the dip cord in the rubber of the tire or the belt during driving. If the thread-thread friction coefficient μs is larger than a certain value,
Due to this stress, slippage between single yarns does not occur, so that stress concentrates locally. However, when the yarn-yarn friction coefficient μs is smaller than a certain value, the stress easily causes slippage between single yarns. Therefore, stress concentration is eliminated. Therefore, fatigue resistance is improved.

As a method for reducing the thread-thread friction, a method of adding a lubricant to the polymer, adding an inorganic substance to the polymer, or adding a finishing agent to the fiber can be considered. Here, a method of lowering the yarn-yarn friction coefficient μs by a finishing agent applied to fibers is disclosed.

The finishing agent is mainly composed of a smoothing agent and an emulsifying agent. Usually, the smoothing agent is related to the smoothness, and the emulsifying agent is related to the bundling property and the antistatic property.

In particular, when producing fibers for tire cords, the fiber is highly stretched in the stretching step, so a finishing agent having a reduced thread-metal friction coefficient μs is used.

Generally, in order to reduce the thread-metal friction coefficient μs, a method of increasing the molecular weight of the smoothing agent is used. However, when the molecular weight of the smoothing agent is increased, the thread-metal friction coefficient μs is lowered, but the thread-thread friction coefficient μs is increased, which are contrary properties.

For this reason, it is very difficult to reduce both the thread-metal friction coefficient μs and the thread-thread friction coefficient μs.

Then, as a result of diligent study, it was found that the yarn-metal friction coefficient μs can be lowered without raising the yarn-metal friction coefficient μs by improving the emulsifier rather than the smoothing agent.

A particularly effective emulsifier for decreasing the thread-thread friction coefficient μs is a polyhydric alcohol ethylene oxide adduct and a monocarboxylic acid and a dicarboxylic acid which are dehydrated under an acidic catalyst to give a number average molecular weight of 5,000 or more. It is a complex ester.

The polyhydric alcohol ethylene oxide adduct is obtained by mainly adding ethylene oxide to a polyhydric alcohol, and includes, for example, hydrogenated castor oil ethylene oxide adduct, castor oil ethylene oxide adduct, hydrogenated castor oil ethylene oxide propylene oxide addition. Such as things. As the dicarboxylic acid, a saturated or unsaturated dicarboxylic acid having 4 to 12 carbon atoms, for example, adipic acid, sebacic acid, maleic acid is used. As the monocarboxylic acid, a saturated or unsaturated monocarboxylic acid having 12 to 32 carbon atoms, for example, stearic acid, dotriacontanoic acid, oleic acid is used.

Generally, an emulsifier having a molecular weight of 1500 to 3000 is used. In the present invention, the emulsifier has a molecular weight of 5000 or more, preferably 8000 or more.
The yarn friction coefficient can be effectively reduced.

Specific examples of emulsifiers that reduce the thread-thread friction coefficient μs include the following. That is, adipic acid and dotriacontanoic acid were added to hydrogenated castor oil ethylene oxide adduct, and paratoluenesulfonic acid was used as a catalyst to
Maleic anhydride and stearic acid are added to a complex ester obtained by dehydration reaction at 190 ° C for 5 to 6 hours or hydrogenated castor oil ethylene oxide adduct, and phosphoric acid is used as a catalyst at 180 to 190 ° C for 10 to 13 ° C. Examples thereof include complex esters obtained by performing a dehydration reaction for a long time.

When the above emulsifier is added to the finishing agent, the yarn-yarn friction is significantly reduced.

These emulsifiers are added to the crude oil of the finishing agent in an amount of 5 to 30% by weight, preferably 10 to 20% by weight. Below 5% by weight,
The effect of reducing thread-thread friction is small, and when it exceeds 30% by weight, the viscosity of the finishing agent becomes high and problems such as single thread breakage occur.

These finishes provide 0.5 to 2.0% by weight, preferably 0.8 to 1.7% by weight, to the fiber. If it is less than 0.5% by weight, the spinnability and drawability are poor, such as the occurrence of cutting threads and fluff. Also, 2.
If it exceeds 0% by weight, problems occur in the subsequent steps such as a decrease in adhesiveness.

Tire cord for high strength, i.e. for rubber reinforcement,
As a method for producing the polyhexamethylene adipamide multifilament yarn of the present invention used for a belt or the like, the following commonly used methods can be used.

That is, polyhexamethylene adipamide having a relative viscosity of 50 or more (relative viscosity at 25 ° C. of a solution prepared by dissolving 90% by weight of formic acid to a polymer concentration of 8.4% by weight) is used.

The melted polymer is spun from a spinneret, the spun yarn is immediately cooled with cooling air, and then a finishing agent is applied to the yarn. After winding the yarn once, it is hot-drawn or immediately taken up by a take-up roll, successively guided to a drawing roll rotating at a higher peripheral speed, subjected to drawing heat setting in multiple stages, and then wound. take. In this way, a high strength drawn yarn can be obtained.

Thread-thread friction coefficient μs of the multifilament thread of the present invention
Using a yarn-yarn friction measuring instrument manufactured by Eiko Sangyo Co., Ltd.
It is measured under the following conditions according to the method described in 48-35112.

That is, a yarn of about 50 m is wound around a cylinder in a substantially untwisted state with a winding angle of ± 15 ° and a winding tension of about 10 g. The cylinder is about 5.1 cm in diameter and about 10 cm long. The same yarn as described above is hung on this cylinder so that it is not twisted, and at this time, this yarn is on the yarn layer of the wound yarn and the winding direction is Make them parallel. A load whose value in grams is equal to 0.04 times the denier of the yarn laid on the cylinder is applied to one end of the yarn laid on it and the other end to the strain gauge. Rotate the cylinder 180 ° at a peripheral speed of 0.0016 cm / sec. At this time, the tension is continuously recorded. The thread-thread friction coefficient μs is calculated using the following equation derived from the equation for the friction of a belt traveling on a cylinder.

μs = 1 / π (1n (T ₁ / T ₀ )) In the above equation, T ₁ is the average value of the tensions of the recorded peaks at least 25 times, and T ₀ is the tension given by the load applied to the yarn. , 1n represents a symbol of natural logarithm, and π represents a circular constant.

The temperature of the measuring room is 25 ° C, the humidity is 60%, and the measuring temperature is 25 ° C.

〔The invention's effect〕

The polyhexamethylene adipamide multifilament yarn of the present invention has excellent fatigue resistance and is useful as an industrial material such as a tire cord material and a belt material.

〔Example〕

 Hereinafter, the present invention will be specifically described with reference to Examples.

Example 1 A polyhexamethylene adipamide chip having a relative viscosity of formic acid dried to a moisture content of 0.1% by weight or less (relative viscosity at 25 ° C. of a solution dissolved in 90% by weight formic acid at a polymer concentration of 8.4% by weight) was used. Spinning was performed using an extruder type spinning machine. The melting temperature at this time was 298 ° C.

A yarn spun from a spinneret having 210 holes with a spinning hole diameter of 0.3 mmφ was immediately cooled with cooling air and then used as an emulsion of 20% by weight of the following finishing agents A to E with respect to the fiber weight. Oil to give a weight ratio of 1.5% by weight, then immediately take it over to the first Nelson roll,
Continue to the second to fourth Nelson rolls rotating at a higher peripheral speed, and set the stretching heat in three stages.
A drawn yarn of 1260d was wound at a speed of 00 m / min.

Assuming that each godet roll group of four stages is G _{1 to} G ₄ , the temperature of each roll is G ₁ : room temperature, G ₂ : 70 ° C, G ₃ : 220 ° C, G ₄ : 230 ° C, and the temperature of each roll is The speed ratio is G ₂ / G ₁ = 1.05, G ₃ / G ₂ = 3.24,
G ₄ / G ₃ = 1.65, was winding speed / G ₄ = 0.91.

These drawn yarns have an average strength of 12.0 kg and elongation of 1
It had a physical property of 8.5%.

45 parts of the finishing agent A sorbitan trioleate, 20 parts of sorbitan trioleate EO _20, 20 parts of a castor oil EO _43, 15 parts of a castor oil EO ₄₃ tristearate.

Finishing agent B Hydrogenated castor oil Ethylene oxide (20 mol) adduct 1850 g
Obtained by adding 88 g (0.6 mol) of adipic acid and 768 g (1.5 mol) of dotriacontanoic acid to (about 1 mol) and performing dehydration reaction at 180 to 190 ° C for 5 to 6 hours using paratoluenesulfonic acid as a catalyst. Acid value 7 to 10, average molecular weight about 80
00 complex ester (hereinafter referred to as complex ester B) is 15
Part, 85 parts of known finishing agent A.

Finishing agent C (higher alcohol EO ₃ ) ₂ 5 thiopropionate
0 parts, 22 parts hydrogenated castor oil EO ₂₂ , 15 parts sorbitol EO ₂₀ higher fatty acid ester, 10 parts higher alcohol EO / PO,
3 parts of alkylamine EO ₁₅ .

Finishing agent D 15 parts of complex ester B used for finishing agent B, finishing agent C
85 copies.

Finishing agent E Hydrogenated castor oil Ethylene oxide (25 mol) adduct 2070 g
78g (0.8mol) of maleic anhydride and 426g (1.5mol) of stearic acid were added to (about 1mol) and phosphoric acid was used as a catalyst for 180
The complex ester having an acid value of 10 to 12 and an average molecular weight of about 5,000 obtained by performing a dehydration reaction at 〜190 ° C. for 10 to 13 hours is
Part, 85 parts of known finishing agent C.

The wound yarn thus drawn was twisted 39 times / 10 cm, and the two twisted twisted yarns were twisted together 39 times / 10 cm to obtain a raw cord.

This raw cord is used by Ritzler's computertor, the first zone is temperature 160 ℃, tension 2.0 kg / cord,
Dip treatment with resorcin formalin latex liquid was performed at time 140 seconds, temperature 230 ° C, tension 3.8 kg / cord, time 40 seconds in the second zone, temperature 230 ° C, tension 2.6 kg / cord, time 40 seconds in the third zone. . 4.5% by weight of adhesive
Met.

Fatigue resistance is in accordance with JIS L-1017 3 ・ 2 ・ 2 ・ 1A method,
A Goodyear tube fatigue test was performed.

Tube shape is 12.5 mm inside diameter, 26 mm outside diameter, 230 mm length
The bending angle is 90 °, the internal pressure is 3.5kg / cm ² G, and the rotation speed is 85.
A fatigue test was performed under the condition of 0 rpm, and the time until the tube burst was measured.

In addition, the yarn-yarn friction coefficient μs of the drawn yarn was measured.

 The results are shown in Table 1.

In this way, the fiber with the low thread-thread friction coefficient μs is
It can be seen that the fatigue resistance is remarkably improved.

Example 2 A polyhexamethylene adipamide chip having a relative viscosity of 79 formic acid dried to a water content of 0.1% by weight or less was used for spinning with an extruder type spinning machine. The melting temperature at this time is
It was 298 ° C.

A yarn spun from a spinneret having 210 holes having a spinning hole diameter of 0.3 mmφ was immediately cooled with cooling air, and then the finishing agents of Example A and B were prepared as 20 wt% emulsion using an oiling roll. Oil content of 1.5% by weight based on fiber weight
After that, it is immediately taken up by the first Nelson roll, then successively guided to the second to fourth Nelson rolls that rotate at a higher peripheral speed, and the stretching heat setting is performed in three stages by 1800 m / min. The drawn yarn of 1260d was wound up at a speed of.

Assuming that each godet roll group of four stages is G _{1 to} G ₄ , the temperature of each roll is G ₁ : room temperature, G ₂ : 70 ° C, G ₃ : 220 ° C, G ₄ : 230 ° C, and the temperature of each roll is The speed ratio is G ₂ / G ₁ = 1.05, G ₃ / G ₂ = 3.35,
G ₄ / G ₃ = 1.65, was winding speed / G ₄ = 0.91.

These drawn yarns have an average strength of 13.0 kg and elongation of 2
It had a physical property of 0.0%.

In the same manner as in Example 1, the drawn yarn was used as a raw cord and subjected to a dip treatment, and the fatigue resistance was measured.

 Further, the yarn-yarn friction coefficient μs of the drawn yarn was measured.

 The results are shown in Table 2.

As described above, when Examples 1 and 2 are compared, the fatigue resistance is increased by increasing the molecular weight of the polymer, but the fiber having a reduced yarn-yarn friction coefficient μs has a significantly improved fatigue resistance. You can see that

Claims (1)

(57) [Claims] 1. A finishing agent containing 5 to 30% by weight of a complex ester having a number average molecular weight of 5000 or more obtained from a polyhydric alcohol ethylene oxide adduct and a monocarboxylic acid or a dicarboxylic acid is 0.5 to 2.0% by weight based on the fiber. %, And a yarn-yarn friction coefficient μ _s satisfies the following expression (1): a polyamide multifilament yarn for industrial materials. μ _s ≦ 0.22 (1)