JPS62133109A - Polycarproamide yarn - Google Patents

Abstract

PURPOSE:The titled yarn having high strength after vulcanization, improved dimensional stability and fatigue resistance in use as a rubber reinforcing agent for tire cord, belt, etc., having specific physical properties such as birefringence, etc., comparing mainly an epsilon-caproamide unit. CONSTITUTION:The aimed yarn comprising polycaproamide yarn having at least >=95mol% epsilon-caproamide unit and high polymerization degree of >=3.0 relative viscosity, DELTAn>=58X10<-3> birefringence, Tmax <=118 deg.C primary dispersion of mechanical dissipation factor (tandelta), Tzep >=188 deg.C melting point by crosslinking freezing method measured by DSC, preferably >=0.92 crystal orientation degree (fc) of yarn, 0.70-0.85 amorphous molecular orientation function (F), >=1.145 density (rho), >=10g/d strength (T/D) of yarn, 10-18% elongation (E) and <=10% boiling water shrinkage percentage.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a high-strength polycapramide fiber, which has improved strength after vulcanization, especially when used as a rubber reinforcing material for tire cords and belts. The present invention relates to a polycapramide fiber having excellent dimensional stability and fatigue resistance.

[Conventional technology]

Polycapramide fiber has excellent properties such as high strength, heat resistance, fatigue resistance, and adhesion to rubber, and is therefore widely used as a cord material for rubber reinforcement. Taking advantage of the above characteristics, it has been useful for large bias tires for trucks, buses, etc. that require particularly durability, but recently competition with steel tires has become fierce even in the field of large tires.
In order to secure market share for Suiron bias tires in the future, further performance improvements and cost reductions are required.

To this end, it is necessary to further improve the dimensional stability and fatigue resistance of polycapramide cords used as tire reinforcing materials. In particular, a tire coat made of polycapramide fibers is embedded in tire rubber and vulcanized, but at this time, after being vulcanized under tension at a high temperature of, for example, 150°C or higher,
Polycapramide fibers have the disadvantage that if they are immediately taken out of the vulcanizer and the tension is relaxed, their strength decreases due to rapid thermal contraction, and there is a strong need to improve this problem.

This is because polycapramide fibers have poor dimensional stability and undergo rapid shrinkage during the vulcanization process, and this shrinkage significantly changes the fiber structure and causes a decrease in strength.

Therefore, it is necessary to reduce the thermal shrinkage rate and to create a stable fiber structure that does not cause a significant decrease in strength even if the shrinkage occurs.

Regarding improvements in the dimensional stability of polycapramide fibers, fibers with improved dimensional stability and reduced strength during vulcanization, and methods for producing the same, see JP-A-57-191337 and JP-A-58-54018. It has been proposed in the following publications. In addition, examples of technologies that have achieved high strength of 10z/d or more by pursuing high strength of polycapramide fibers include JP-A-58-98415 and JP-A-58-13.
Many proposals have been made, such as Publication No. 6823.

[Problem that the invention seeks to solve]

JP-A-57-19337 discloses polycapramide fibers having a relative viscosity of 3.0 or more. 1500m/
This disclosure discloses a method in which the undrawn yarn obtained by high-speed spinning is carried out at a speed of min. min, and the obtained undrawn yarn is stretched at at least 85% or more of the maximum draw ratio, and then twisted to form a rubber reinforcing cord. By this method, polycapramide fibers with improved dimensional stability and reduced strength during vulcanization have been obtained. However, the strength of this fiber is less than 9 g/d, which is rather low compared to conventional polycapramide fibers, and the strength utilization rate in the subsequent tire cord processing process and the decrease in strength during vulcanization have been improved. However, the absolute value of its strength has not reached a satisfactory level. For example, according to FIG. 2 of the example of this patent application, the cutting strength of the cord when vulcanized at 160° C. is improved by only about 5 to 10% compared to conventional fibers.

Furthermore, JP-A-58-54018 proposes a polycapramide fiber with low shrinkage rate and excellent fatigue resistance and a method for producing the same, but the strength of the polycapramide fiber is less than 9.1 g/d as mentioned above. Although the strength utilization rate in the tire cord processing process has been improved, the tire coat (
The values for treated coats) are rather low compared to conventional coats.

In other words, although both technologies have attempted to improve the useful properties of the tire coat, such as dimensional stability, reduced strength during vulcanization, and fatigue resistance, the fibers that make up the tire cord fibers themselves have low strength. It is insufficient in terms of obtaining a high absolute value of strength after sulfurization.

On the other hand, JP-A-58-98415, JP-A-58-1368
Publication No. 23 Natote pursues high fiber strength and achieves 10 g/d by low-speed spinning and drawing process, but the fibers obtained by this method do not have sufficient dimensional stability and cannot be vulcanized. Rear strength is never high.

Therefore, the object of the present invention is to provide a polycapramide fiber that has high strength after vulcanization, improved dimensional stability, and fatigue resistance when used as a rubber reinforcing material in tire cords, belts, etc., and that is a stable fiber. An object of the present invention is to provide a polycapramide fiber characterized by its structure. In particular, by improving the structural defects that cause a significant decrease in strength when subjected to rapid temperature changes during the rubber vulcanization process, the strength after vulcanization has been improved by at least 10% compared to conventional polycapramide fibers. The aim is to provide fiber.

[Means for solving problems]

The present invention provides a polycapramide fiber with a high degree of polymerization, in which at least 95 mol% or more is composed of ε-capramide units and has a relative viscosity of sulfuric acid of 3.0 or more, (a) birefringence Δn≧58
X 10'' (b) Main dispersion peak temperature of mechanical loss tangent (tan δ) T max≦118°C (c) Crosslinking freezing method melting point measured by DSC T zep≧1
It is a polycapramide fiber with a fiber structure parameter of 88°C.

Further, the fiber of the present invention has (d) degree of crystal orientation fc≧0.92 (e) amorphous molecular orientation function F=0.70 to 0° (f) density ρ≧1, 145 (g/cc) fiber structure parameters. A more preferable polycapramide-based fiber can be obtained by having both of these properties.

By satisfying the fiber structure parameters (A) to (C), more preferably (D) to (F), (G) Strength T/D≧10g/d (H) Elongation E=10 to It is a polycapramide fiber characterized by having fiber properties of 18% boiling yield and 68510%.

[Effect]

In the present invention, it is necessary that the birefringence of the fiber is 58×10°3 or more. It is usually eoxio' to 6δ x 10°3, which is more highly oriented than conventional polycapramide fibers. 5
If it is less than 8 x 10', a tire cord with a fiber strength of 10 g1d or more and high strength after vulcanization cannot be obtained.

The main dispersion peak temperature of the mechanical loss tangent is 118°C or less, preferably 115°C or less. This characteristic indicates the mobility of the amorphous molecular chains at high temperatures, meaning that they are more mobile at relatively low temperatures than conventional high-strength yarns. If the main dispersion temperature of the mechanical loss tangent is set to 118-(: or less), when used as a tire cord, it will have excellent dimensional stability and fatigue resistance, and a decrease in strength during vulcanization can be suppressed.118-C If it exceeds, the above-mentioned improvement effect cannot be obtained.

The crosslinking freezing method melting point measured by DSC needs to be 188°C or higher. The melting point of this cross-linking and freezing method is the peak temperature of the melting curve obtained by irradiating the fiber with gamma rays in an acetylene gas atmosphere to cross-link and freeze the amorphous portion, and then measuring it by DSC. The high melting point of this cross-linking freezing method means that the crystal structure is thermally stable, which also means that the entire fiber structure is thermally stable.

As mentioned above, the decrease in strength of polycapramide fibers during vulcanization corresponds to the magnitude of structural changes caused by rapid shrinkage during the vulcanization process. We have carefully considered this as one of the important requirements,
This invention! & I was able to obtain the results. Cross-linking freezing method melting point is 188
If the temperature is below .degree. C., polycapramide fibers having high strength after vulcanization cannot be obtained. The degree of crystal orientation needs to be 0.92 or more.

If it is less than 0.92, a tire cord with a fiber strength of 10 g/d or more and high strength after vulcanization cannot be obtained.

The amorphous molecular orientation function is 0.70-0.85.

Polycapramide fibers with a molecular weight of less than 0.70 are disclosed in the above-mentioned Japanese Patent Application Laid-open No. 58
Although it is proposed in Publication No. 54018, the strength of the raw yarn (novel yarn) is high, like the polycapramide 1m fiber of the present invention,
In addition, it must be as high as 0.70 to 0.85 in order to suppress a decrease in strength during the tire cord processing process, especially during vulcanization, and to obtain a high absolute value of strength after vulcanization. on the other hand,
When this value exceeds 0°85, the amorphous molecular chains become too oriented.
Dimensional stability and fatigue resistance are not improved. Although such fibers have high strength, their strength after vulcanization is rather low.

The fiber density is 1.145 or more, which is higher than conventional high-strength polycapramide fibers, and preferably 1.148 or more. High density reflects the stability of the crystal structure and, by extension, the overall fiber structure, and contributes to high strength after vulcanization, especially to suppressing the rate of strength loss during vulcanization. Therefore, the density is 1, 14
If it is less than 53/cc, high strength after vulcanization cannot be achieved.

The polycapramide fiber of the present invention has a stable fiber structure by having the above-mentioned fiber structure parameters, and is particularly stable against severe thermal and mechanical effects during tire manufacturing processes and tire use. Furthermore, the polyamide fiber of the present invention has the following fiber properties.

That is, the strength is 10 g/d or more, usually 11 g/d or more, and the elongation is 10 to 18%, which is higher strength and lower elongation than conventional fibers. Despite its high strength and low elongation, the boiling point is 1.
It is characterized by its excellent dimensional stability, which is as low as 0% or less, usually 2 to 8%.

As described above, the polycapramide fiber of the present invention is characterized by the above-mentioned fiber structure parameters and fiber properties, and this means that we have obtained a fiber that simultaneously satisfies the seemingly contradictory structural parameters from the conventional general fiber common sense. It means that. As a result, it was possible to obtain a polycapramide fiber that has high strength, particularly when used as a tire cord, is strong after vulcanization, and also has dimensional stability and fatigue resistance. For example, the aforementioned Japanese Patent Publication No. 58-984.15,
As disclosed in Japanese Unexamined Patent Publication No. 58-136823, the common characteristics of polycapramide fibers obtained by pursuing strength through a low-speed spinning/hot drawing process are high birefringence, high degree of crystal orientation, etc. On the other hand, fibers with improved dimensional stability and fatigue resistance obtained by high-speed spinning/hot drawing, as proposed in JP-A-58-54018, have a low amorphous molecular orientation function, a low density It has characteristics such as low

However, the polycapramide fiber of the present invention is characterized in that it simultaneously satisfies both of the above-mentioned fiber structure parameters that are closely related to the expression of properties useful as a tire cord, and furthermore, it has a low main dispersion peak temperature of the mechanical loss tangent, and Due to the characteristics such as high melting point of cross-linking freezing method measured by DSC! By further specifying the 1' fiber structure, it can be clearly distinguished from conventional polycapramide fibers.

The novel high-strength polyamide fiber according to the present invention can be produced by a special method as described below.

The method of the present invention is the high-speed spinning/
A new method was completed by effectively employing the hot drawing method and the method applied to the production of conventional high-strength polycapramide fibers. In other words, by eliminating the contamination of foreign matter into the fibers, improving uniformity, and adopting a drawing method suitable for undrawn yarn obtained by high-speed spinning, we have achieved high strength and This is because we have set up a special spinning/drawing method that allows stable drawing until a low elongation is reached. That is, (Spinning method) A. Use of one or more antioxidants containing copper salt;
When adding n, the amount of copper salt is 1100 pp or less as copper,
B. Immediately before spinning from the spinneret, the molten polymer is passed through a filter having pores of 20 μm or less, preferably 10 μm or less, so as to mainly contain copper salts. To avoid foreign matter generated by thermal decomposition of antioxidants from entering the yarn, the C1 spun yarn is passed through a cooling delay zone surrounded by areas heated above the melting point of polycapramide, and then cooled with cold air. When the yarn is taken after being rapidly cooled and solidified, the birefringence of the taken-up yarn should be 20 x 10-3 or more and 45 x 10-3 or less. (Stretching method) A. In performing multi-stage stretching, stretching is performed by providing a non-contact heating element such as a slit heater or superheated steam between the stretching rolls. When stretching with a group of stretching rolls, the yarn is wound around the intermediate stretching roll no more than 4 times,
It consists of stretching until the residual elongation becomes 10 to 18%.

Next, the method for producing the fiber of the present invention will be described in detail.

More than 95 mol% of the polycapramide used in the present invention is ε-
It consists of capramide units and may contain less than 5 mol% of a copolymer component. Other amide-forming units that can be copolymerized include dicarboxylic acids such as adipic acid, sebacic acid, terephthalic acid, and isophthalic acid, and diamines such as tetramethylene diamine, hexamethylene diamine, metaxylylene diamine, and the like. In addition, less than 5% by weight of polytetramethylene adipamide, polyhexamethylene adipamide, polyhexamethylene adipamide, polyhexamethylene terephthalamide,
It is also possible to blend polyhexamethylene isophthalamide. When the copolymerization component is 5 mol% and the above blend polymer is 5% by weight or more5, the desired dimensional stability,
And high post-vulcanization strength cannot be achieved.

The polycapramide-based polymer of the present invention has a sulfuric acid relative viscosity of 3.0 or more, preferably 3.2 to 4.5.The sulfuric acid relative viscosity here means fL when dissolved in acid to a polymer concentration of 1% by weight, Solution relative viscosity measured at 25°C.

In addition, since the polycapramide-based V&fiber of the present invention is mainly used for industrial materials such as rubber reinforcing materials, it contains an antioxidant in order to provide sufficient durability against heat, light, oxygen, etc. . Antioxidants include, for example, copper acetate and dichloride.
Copper compounds such as copper, copper iodide, potassium iodide, potassium bromide, triethylphthylammonium iodide, halogen compounds such as pentayodobenzene, N,N'-di-β-naphthyl-p-phenylenediamine, 2 -Mercaptobenzimidazole, tetrakis-[methylene-
Organic antioxidants such as 3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate-co-methane are used. Copper compound is 100 ppm as copper
Below, 20 to 80 ppm is particularly preferable.

A smaller amount of copper salt is used than in conventional high-strength polycapramide fibers, but in this case, the same level of heat resistance, light resistance, and oxidation resistance as in conventional fibers can be maintained by using 0.05% by weight or more of the halogen compound. Other antioxidants used in combination with the copper salt include the above-mentioned iodine compound and/or other antioxidants, each of which is used in an amount of 0.05 to 0.5% by weight. The above polycapramide polymer has a moisture content of 0.
It is dried to a weight of 0.055 mm or less and then melt-spun, preferably using an extruder type spinning machine. Melting temperature is 270
~310°C is preferred.

Immediately before spinning the polymer from the spinneret (1), the molten polymer is filtered for the purpose of removing foreign matter. At this time, the filter is a wire mesh having pores of 20 μm or less, preferably 10 to 3 μm. It is necessary to remove foreign matter generated by the decomposition of the antioxidant containing the copper salt and foreign matter mixed into the polymer before spinning to avoid contamination of the spun yarn with foreign matter. The amount of foreign matter permissible in the polycapramide fiber of the present invention is, for example, "Old A
When a fiber sample is dissolved in a phenol/tetrachloroethane solution and measured using C4100, the number of foreign particles of 5 μ or more in 1 g of the sample is 1000 or less.

Next, in order to delay the cooling of the spun yarn (Y) in an area at least 10 cm or more from the spinneret surface of the spinning machine,
It is necessary to maintain the atmosphere at a temperature of 250°C or higher and 400°C or lower. Therefore, a heating tube (2) of 5 cm or more, preferably 10 to 100 cm, is attached directly below the cap.

After passing through the above-mentioned delay zone, the spun yarn is passed through the cooling device (3
) is cooled and solidified with cold air, applied with oil by an oil supply device (4), and then its speed is controlled by a take-up roll (5).
It is wound up by a winding machine (7).

Take-up speed (also called spinning speed) is 1500 m/min
The above speed is preferably 2000 to 6000 m/min. The birefringence of this drawn thread is 20X10' to 45X10
'is. If the birefringence is less than 20X10"3, the dimensional stability of the subsequently drawn fibers will be poor, and the strength will decrease significantly during vulcanization, making it impossible to obtain the effects of the present invention. On the other hand, if the birefringence is less than 20X10"
If it exceeds 0', high strength fibers cannot be obtained even by the drawing method of the present invention. If the spinning speed is less than 3000 m/min, the polycapramide fiber will swell vertically and cannot be wound normally. Therefore, when producing the fiber according to the present invention from an undrawn yarn with no grooves at 3000 m/min, the spun yarn is taken off with a take-up roll and then continuously stretched by a factor of 2 times or less using a drawing roll (6 ) and then wind it up. In this case, it is preferable to use a heating roll heated to 100° C. or lower as the take-up roll and 150° C. or lower as the stretching roll. It is preferable to select the lowest possible stretching ratio for the stretching to prevent vertical swelling, which does not cause vertical swelling and allows normal winding, and the spinning speed is 3000 m/min.
The birefringence of the drawn yarn may be approximately equal to 35 x 10'. Next, the undrawn yarn (8
) is stretched at a maximum stretching ratio of 92% or more. The maximum stretching ratio herein refers to the highest stretching ratio at which a sample with a length of 500 m or more can be obtained. As for the stretching method, multi-stage hot stretching of two or more stages is preferred, and since the undrawn yarn according to the present invention has already achieved high orientation, the total stretching ratio is 3.5 times or less, usually 3.0 to 1. That's four times as much. Incidentally, the total stretching ratio refers to the total stretching ratio including the continuous stretching performed for the purpose of preventing longitudinal swelling after the above-mentioned spun yarn is taken up with a take-up roll.

In order to obtain the polycapramide fiber of the present invention, it is drawn at a high magnification to a lower elongation than conventional polycapramide fibers so that the residual elongation is 10 to 18%.

Since the polycapramide fiber according to the present invention is a uniform fiber containing almost no decomposed foreign substances of antioxidants, it can be stably drawn to low elongation, and after drawing, it has a highly oriented wk fiber structure. It is characterized by the fact that it is maintained. As a result, high strength and low elongation are achieved, and birefringence is 58X1.
Highly oriented fibers of 0" or more are obtained.

An example of the stretching method of the present invention is shown in FIG. 1, and the details will be as follows. As the stretching rolls in the present invention, a commonly used Nelson roll unit using two pairs of actively driven rolls or a combination of actively driven rolls and free rolls is used. The distance between FR (feed roll: 9) and IDR (first draw roll: 10) is 1.
05~2.0, IDR and 2DR (, 2nd draw roll:
12) Between 1.1 to 1.5 0.2 DR and 3DR (third draw roll: 14) is 1.05 to 1.50.3 DR and R, R (tension adjustment roll: 15) is 0°90 ~1.1
The stretching ratio is distributed so that it becomes 0.

FR is unheated to 100℃, IDR is 60 to 150℃, 2
DR is 100-200℃53DR is 150-220℃,
RR is used without heating to 200°C.

A non-contact heating element such as a slit heater or superheated steam is provided between the IDR and 2DR and between the 2DR and 3DR. IDR
and 2DR when using a slit heater between 80 and 2DR.
Let it pass through a high-temperature atmosphere of 50°C for 0°2 seconds, and when using superheated steam, inject high-temperature steam with a nozzle temperature of 150 to 300°C from a high-temperature pressurized steam nozzle. In addition, when installing between 2DR and 3DR, the slit heater should be 150℃ or higher, and the superheated steam should be 200℃ or higher.
The temperature is set higher than that between IDR and 2DR. The drawing method in the production of the fiber of the present invention is characterized by using the above-mentioned non-contact heating body and a group of heating rolls. It is necessary to keep the number of times or less. For satin rolls, 2 to 4 times are good, and for mirror rolls, 1 to 2 times is good. It is preferable to keep the thermal history applied by the heating roll to the minimum required for stretching.

The thus obtained fiber has the characteristics of the polycabrame 1 type fiber of the present invention.

[Example] Next, the method for measuring fiber structure parameters and fiber properties according to the present invention will be explained based on Examples.

(a) Birefringence Δn It was determined by a conventional method using a Nikon polarizing microscope, POH type, using the Bettsukukoshipensator method.

(Note) Principal dispersion peak temperature of mechanical tangent loss (tanδ) T max “Vibron DDV-2” manufactured by Toyo Baldwin ■
"Using a mold machine, frequency 110Hz, temperature increase rate 3°C/m
The measurements were taken in an air bath.

(c) Melting point of cross-linking freezing method Tzep Tentoki, Kawaguchi. , Heat Measurement, 1 2(1), 2-1
0.

(1985) method. The crosslinking freezing method melting point and the 2ep melting point are synonymous.

Place the sample in a glass container, create a vacuum of about 10-2 mm}Ig, and then apply acetylene gas to about 600 m
The tube is sealed at mHg and irradiated with gamma rays at room temperature. Source 60Co
So, the dose is 5X10 radh, and the total irradiation dose is O~
It was 20 Mrad. Since the amorphous portion of the treated fiber is cross-linked and frozen, it is possible to measure the melting point of imperfect crystals unique to the sample. The melting point was defined as the peak temperature of the melting curve measured with a Perkin-Elmer DSC-IB model. The measurement conditions were a heating rate of 10 km'', a sample amount of 4.0 mg, and a sensitivity of 4 mcal·S full scale.

(d) Crystal orientation fc Using a wide-angle X-ray scattering device D3-F manufactured by Rigaku
Measurements were made using Kα as a radiation source. The orientation function of the crystal part is fc
It was calculated from the half-width H of the intensity distribution curve along the Tehi ring of (200) equatorial interference using the following formula.

fc=(180°-H')/180°(e) Amorphous molecular orientation function F The sample was immersed in a 0.2% aqueous solution of the fluorescent agent "Whitex RP" (manufactured by Sumitomo Chemical) at 20°C for 2 hours. ,
Next, it was thoroughly washed and air-dried to prepare a measurement sample. The relative intensity of polarized fluorescence was measured using a FOM-1 polarization photometer manufactured by JASCO ■, and F was determined by the following formula.

1"=1-B/A However, A: Relative intensity of polarized fluorescence in the direction of the fiber axis B: Relative intensity (to) density in the direction perpendicular to the fiber axis ρ Using a density gradient tube made of carbon tetrachloride-toluene, 25
Measured at °C.

(g) Strength T/D and elongation E According to JIS-L1017. Take the sample in the form of a cold, and
After being left in a temperature and humidity controlled room at 0°C and 165% RH for more than 24 hours, a 25 cm
, measured at a tensile speed of 30 cm/min.

, (H) Boiling yield △S Take a sample in the form of a skein, leave it in a temperature and humidity controlled room at 20°C and 165% RH for more than 24 hours, and then place a sample with a length LO corresponding to 0°18/d of the sample in a cloth bag. and place in boiling water for 30 minutes without tension. The sample after treatment was air-dried, left in the above-mentioned temperature and humidity control room for 24 hours or more, and the above-mentioned load was applied again, and the measured length was calculated using the following formula.

Boiling yield (%) = (Lo-L) / L0x 100 [Examples-1 to -5 and Comparative Examples-1 to -4] Copper acetate 0.0
15% by weight (52 ppm as copper), 0 potassium iodide
．． 1% by weight, and 0 2-mercaptobenzimidazole
．． Nylon chips containing 1% by weight and having ηr = 4.0 were spun using an extruder-type spinning machine as shown in FIG. The discharge amount was adjusted so that the fineness of the drawn yarn was 630 denier (D) when the spinning speed was less than 3000 m/min, and 420 D when the spinning speed was 3000 m/min or more. In addition, when the spinneret has a hole diameter of 0.3 mmφ and the spinning speed is less than 3000 m/min, the
For speeds of 0 holes and 3000 m/min or more, 60 holes were used. The polymer temperature was 290°C. Approximately 100
After filtering through a pack consisting of a metal powder having a mesh roughness and a metal wire mesh having pores of 7 μm arranged in sequence, the powder was spun through a spinneret spinning hole. In order to maintain the atmosphere within 25 cm below the cap to 300° C., a 20 cm long heating cylinder was attached directly below the cap. The spun yarn was passed through the heating cylinder in a high-temperature atmosphere, and then passed through a 120 cm long uniflow type chimney to be rapidly cooled. Cold air is 20℃, 30m/
I sprayed min.

After the spun yarn was cooled and solidified, 1% by weight of an aqueous emulsion was applied to the yarn using oil supply rolls arranged in two stages facing the yarn. Next, the yarn was taken up by a take-up roll rotating at a predetermined speed and wound up as is, or it was continuously stretched between drawing rolls and then wound up. The undrawn yarn was then drawn in three stages using the drawing machine shown in FIG. 2, heat treated, and then wound to obtain a drawn yarn. Two or three drawn yarns were combined to obtain a 1260D yarn. The spinning and drawing conditions are shown in Table 1, and the properties of the obtained yarn are shown in Table 2.

Next, the raw yarn is first twisted to 39T/10cm, and then the two first twisted cords are combined to 39T/10cm in the opposite direction to the first twist.
A raw cord was made by twisting the cord.

Next, an adhesive application process was performed using a dipping machine manufactured by Ritzler. It was immersed in RFL liquid, and the liquid temperature and liquid draining conditions were adjusted to 114 degrees and the liquid draining conditions so that the adhesion was 5%.

The drying zone was heated to 130°C for 90 seconds at a constant length, and the heat treatment zone was heated to 200°C for 40 seconds.
It was stretched so that it passed. Normal sawn was passed through at 200° C. for 40 seconds with 1% relaxation.

The treated coat was subjected to rubber vulcanization treatment, and the strength after vulcanization was measured. The vulcanization treatment conditions are as follows. Place the treated cord parallel to the unvulcanized rubber sheet and set it in the mold together with another unvulcanized rubber sheet.
Vulcanization treatment was performed for 30 minutes using a heat press machine at ℃. Immediately after taking out the mold from the heat press machine, the mold was cooled with water to allow the cord in the rubber to rapidly contract freely. Next, the coat was taken out from the rubber seal and left in a temperature/humidity controlled room for 24 hours or more, and the strength after vulcanization was measured.

The properties of the treated cord and coat after vulcanization are shown in Table 3.

The method for measuring the coating properties is as follows.

(1) Dry heat shrinkage rate △SD It was measured in the same manner as the boiling yield of the yarn described above, except that the treatment was carried out in an open environment at 177°C.

(2> Intermediate elongation ME Similar to the strength and elongation described above, the elongation at 6.75 kg was determined on the load-elongation curve of the cord and was defined as the intermediate elongation.

(3) Strong utilization rate Strong utilization rate = (Treated coat strong / Yarn strong x 2) x 10
0 (%) (4) GY fatigue life JIS L-10173, 2, 2, 1 (+>A method).

Regarding the fiber structure parameters and fiber properties in Table 2, Comparative Example-1 has Tmax, Tzep, /), and △S
However, in Comparative Example-2, Tmax, Tzep, and U△S
In Comparative Example-3, Δn, Tzep, ρ, and E, and in Comparative Example-4, Δn, p, T/D, and E do not satisfy the range of the present invention.

As a result, in the tire coating properties shown in Table 3, Examples-1 to Example-5 according to the present invention had high strength, low shrinkage rate,
While it has excellent properties such as high fatigue resistance and high strength after vulcanization,
Comparative Example-1 and Comparative Example-2 have sufficient strength, but have high shrinkage rates, low fatigue resistance, and low strength after vulcanization. Comparative example-3
is inferior in strength, shrinkage rate, fatigue resistance, and strength after vulcanization. Comparative Example 4 has a good shrinkage rate and fatigue resistance, and also has a good strength utilization rate after vulcanization, and has a low treatment coat strength, so the absolute value of the strength after vulcanization is not high.

As mentioned above, in order to satisfy useful tire cord characteristics, it is necessary that the polycapramide fiber satisfies the structural parameters and fiber characteristics specified in the present invention.

[Comparative Examples -5 to -6] Antioxidant was added to acetic acid steel 0.04% by weight (140% by weight of copper binding)
Examples -1 to -5 and Comparative Examples -1 to -4 except that the 2-mercaptohensoimigsol material was changed to a metal filter having approximately 30μ metal particles and 46μ pores. It was spun in the same way. In addition, the stretching method was changed to a normal hot plate instead of using a slit heater and heated steam, and the yarn was wound around the intermediate stretching roll 5 times or more for stretching. ~-5
, and stretched in the same manner as in Comparative Examples -1 to -4. The respective spinning, drawing conditions, raw yarn properties, treated coating properties, and vulcanized cord properties are shown in Tables 1, 2, and 3.

Since none of them satisfy the structural parameters and fiber properties specified in the present invention, they do not exhibit sufficient tire cord properties.

〔Effect of the invention〕

The effects of the present invention are as follows.

(1) Due to its high yarn strength of 11 g/d or more, and its excellent dimensional stability and fatigue resistance, it can be used in various industrial applications, such as tire coats, rubber reinforcement cords for belts, conveyor belts, etc. It also becomes a highly durable product when used in ropes, seat healds, sewing threads, fishing nets, various cover sheets, etc. Furthermore, since the dimensional stability is good, the production yield is also improved.

(2) Not only the raw yarn strength but also the strength utilization rate in the subsequent tire coating processing process is high, so both the raw coat and treated coat strength are high, and especially the strength deterioration in the vulcanization process during tire processing is small. , the strength of the coat after vulcanization is at least 10% compared to TireCo-1 made of conventional fibers.
More expensive than that. By taking advantage of this feature, a tire with unprecedented high durability can be obtained, and the amount of material used can be reduced, resulting in a lightweight tire.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing one embodiment of the spinning process according to the present invention. FIG. 2 is a process diagram showing one embodiment of the stretching method according to the present invention. FIG. 3 is a graph showing changes in strength during the tire cord processing process. Y... Spun yarn 8... Undrawn yarn 1... Spinneret 9... Feet roll 2... Heating tube 10. ...First toco roll 3...Cooling device 11...
...Sleeve I/Heater 4...Oil supply device
12...Second draw roll 5...Take-up roll 13...Superheated steam device 6...
Stretching roll 14...Third draw roll 7...
... Winding machine 15 ... Tension adjustment roll 16 ... Winding machine

Claims (3)

[Claims] (1) A polycapramide fiber with a high degree of polymerization, consisting of at least 95 mol% or more of ε-capramide units and having a relative viscosity of sulfuric acid of 3.0 or more, characterized by having the following characteristics (a) to (c). polycapramide fiber. (a) Birefringence Δn≧58×10＾-＾3 (b) Main dispersion peak temperature of mechanical loss tangent (tanδ) Tmax≦118℃ (c) Crosslinking freezing method melting point Tzep≧188℃ measured by DSC (2) The degree of crystal orientation (fc) of the fiber is 0.92 or more, the amorphous molecular orientation function (F) is 0.70 to 0.85, and the density (ρ)
1.145 or more, the polycapramide fiber according to claim (1). (3) Fiber strength (T/D) is 10 g/d or more, elongation (
The polycapramide fiber according to claim 1, wherein E) is 10 to 18% and boiling yield is 10% or less.