JPH0323643B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to polyhexamethylene adipamide (hereinafter also referred to as nylon 66) fiber, particularly nylon 66 fiber suitable as an industrial material. Nylon 66 fiber has excellent strength, toughness, and durability, so it can be used for various industrial purposes, such as rubber reinforcement cords for tire cords, power transmission belts, conveyor belts, seat belts, sewing thread, fishing nets, etc. Used for various cover sheets, etc. Although nylon 66 fiber has slightly better heat resistance, dimensional stability, and initial modulus than nylon 6 fiber, its biggest drawback is that it has lower dimensional stability and initial modulus than other materials used for industrial purposes. It was a shortcoming. Therefore, in addition to the excellent high strength, toughness, and durability of nylon 66 fiber, if it were given dimensional stability and high initial modulus, its uses would further expand, so improvements have been sought for a long time. <Means and Actions for Solving the Problems> The present inventors have made extensive efforts to obtain nylon 66 fibers that are highly strong and have excellent initial modulus and dimensional stability, and as a result, they have arrived at the present invention. That is, the fiber according to the present invention is produced by melt-spinning and stretching polyhexamethylene adipamide, in which the repeating structural unit of hexamethylene adipamide is 95 mol% or more and the relative viscosity of sulfuric acid is 2.8 or more. of,
melting polyhexamethylene adipamide and then spinning it through a spinneret; covering an area of at least 10 cm or more from the spinneret surface with the yarn spun from the spinneret;
And after passing through a heating zone heated above the melting point of polyhexamethylene adipamide, the spun yarn is quenched by blowing cold air, and the spun yarn is taken up at a spinning speed of 2000 m/min or more, and taken up. The birefringence of the drawn yarn that has passed through the roll is within the range of 25 × 10 ^-3 or more and 45 × 10 ^-3 or less, and the single yarn denier of the drawn yarn is 15 denier or less; It can be obtained by hot stretching after winding or without winding at a stretching ratio of 3.5 times or less. By this method, the nylon 66 fiber according to the present invention can be obtained. The structure of the present invention is such that the repeating structural unit of hexamethylene adipamide is
Polyhexamethylene fibers made of polyhexamethylene adipamide with a relative viscosity of 95 mol% or more and a sulfuric acid relative viscosity of 2.8 or more, which have the following properties at the same time: high strength, and significantly improved dimensional stability and fatigue resistance. Adipamide fiber. (a) T/D≧7.5g/d (b) 30≧E≧12% (c) Mi≧28g/d (d) ΔS≦4% (e) fc≧0.92 (f) ≦0.70 In addition, in the above T/D is the strength, E is the residual elongation, Mi is the initial modulus, ΔS is the dry heat shrinkage rate at 177°C, fc is the degree of crystal orientation, and is the degree of amorphous molecular orientation. It is in. The extremely important structural characteristics of the polyhexamethylene adipamide fiber according to the present invention are as follows: (e) fc≧0.92: high degree of crystal orientation (f) ≦0.70: low degree of amorphous molecular orientation. It is to be. In other words,
The fiber according to the present invention has a clear two-phase structure, and a high degree of crystal orientation contributes to high strength and high modulus, and a low degree of amorphous orientation contributes to low shrinkage and high fatigue resistance. The fiber according to the present invention is required to satisfy (e) and (f) of the above formula, but since both parameters alone cannot exhibit all the structural features of the present invention, the fiber of the above formula (a) is required. The auxiliary parameters shown in ~(d) were used. That is, (a) T/D≧7.5g/d, (c) Mi≧28g/
In order to satisfy E≦30% of d and (b), it is necessary to set fc≧0.92, and (d) ΔS≦4%
and (b) To satisfy E≧12%, F≦0.92
It is necessary to The polyhexamethylene adipamide fiber of the present invention has never been seen before, and is particularly characterized by its thread physical properties of high strength, high modulus, and low shrinkage. More specifically, the characteristics of the fiber according to the present invention obtained by the above method will be explained in detail. The raw material polymer is 95 mol% of the number of repeating units in the molecular chain.
The above polyhexamethylene adipamide may contain less than 5 mol% of the copolymer component. Other copolymerizable polyamide components include, for example, poly-ε-capramide, polyhexamethylene sebacamide, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polyxylylene phthalamide, and the like. If the copolymer component is contained in an amount of 5 mol % or more, crystallinity and dimensional stability are reduced, which is not preferable. Nylon 66 polymer (hereinafter also referred to as polymer) was measured at 26℃ using an Ostwald viscometer at a polymer concentration of 1.
The relative viscosity of sulfuric acid measured in weight% is 2.8 or more, especially
High polymerization degree polymers of 3.0 or higher are preferred for obtaining the high strength yarns of the present invention. Furthermore, since the nylon 66 fiber of the present invention is mainly used for industrial purposes, an antioxidant is added to the polymer in order to provide sufficient durability against heat, light, oxygen, etc. Copper salts as antioxidants, such as copper acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, copper phthalate, copper stearate, copper pyrophosphate etc. and chain salts of various copper salts and organic compounds such as 8-oxyquinoline copper, 2
- Copper chain salts of mercaptobenzimidazole, preferably copper chain salts of copper acetate, cuprous iodide and 2-mercaptobenzimidazole, etc. are halides of alkali or alkaline earth metals, such as sodium iodide, potassium bromide, chloride, etc. Potassium, sodium bromide, zinc iodide, calcium iodide are organic halides, such as pentaiodobenzene, hexabromobenzene, tetraiodoterephthalic acid, methylene iodide, tetraiodoammonium iodide, tributylethylammonium iodide, etc. Inorganic and organic neighboring compounds, such as sodium pyrophosphate, sodium phosphite, trifluorophosphite, 9,10-dihydro-10-(3',5'-di-tert-butyl-4'-hydroxybenzyl)- 9-
Oxa-perfluorosphenthrene-10-oxide, etc. and phenolic antioxidants, such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4-hydroxyphenyl)-propionate] -methane, 1,3,5-trimethyl-2,4,
6-tris[3,5-di-t-butyl-4-hydroxybenzyl)benzene, n-octadecyl-
3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate, 4-hydroxy-
3,5-di-t-butylbenzyl phosphate diethyl ester, etc. and amine antioxidants, such as N,
N'-β naphthyl-P-phenylenediamine, 2
-mercaptobenzimidazole, phenyl-β
-naphthylamine, N,N'-diphenyl-P-
It is preferable to use a combination of an alkali metal halide such as phenylene diamine or a condensation reaction product of diphenylamine and allyl ketone, preferably potassium iodide or potassium bromide, and an organic compound for spinning. The antioxidant can be added during the polymerization process of the polymer or once it is made into chips and then sprinkled on the chips. The amount of antioxidant to be included is 10 to 1000 ppm, preferably 30 to 200 ppm as copper salt,
Other antioxidants are 0.01~0.5% preferably 0.05~
Use within the range of 0.2%. The antioxidant is usually used alone or in combination of a copper salt and other antioxidants. The above polymer dried to a moisture content of 0.1% or less is first
Spinning is carried out using a melt spinning machine as shown in the figure (process diagram showing the spinning process of the present invention), and preferably an extruder type spinning machine is used at this time. By the way, other polymers that can be melt-spun to obtain high-strength fibers, such as nylon 66, have a higher crystallization rate and are easier to crystallize than polyethylene terephthalate, so spherulites are more likely to form during the spinning process. A terminally drawn yarn in which spherulites have significantly grown has poor drawability, and a strength of 7.5 g/d or higher cannot be obtained.
In particular, in systems in which spinning and drawing are carried out separately, spherulite formation has a significant effect on deterioration of drawability and strength. The formation of spherulites is determined by the time the molten polymer remains in the crystallization temperature range before being spun and withdrawn. To prevent the formation of spherulites,
It is necessary to perform rapid cooling so that the residence time in the spherulite formation temperature range is shortened. For this reason, there are methods of lowering the temperature of the cooling air or cooling with a high wind speed in order to cool the spun polymer from the melting temperature to the amorphous region as quickly as possible, but with these methods, the cooling between each single filament is Non-uniform fiber yarns with different degrees of orientation can be obtained due to different cooling speeds or different cooling rate distributions within the cross section of the single filament. This influence cannot be ignored, especially when high-speed spinning according to the present invention is employed. Therefore, in order to effectively cool the cooling condition by using a normal method that maintains uniformity, for example, using wind at a temperature of 15 to 30°C at a speed of 10 to 60 m/min, undrawn yarn is It is necessary to set the single yarn fineness to 15 denier or less, preferably 10 to 2 denier, and perform spinning. If the single filament fineness of the undrawn yarn is set to a denier exceeding 15 denier, the amount of single hole discharge from the die increases, so uniform cooling and suppression of spherulite formation cannot be achieved at the same time. Now, the spun yarn Y spun from the spinneret 1 is cooled and solidified, and then taken off by a take-off roller 6. After the take-up speed is adjusted by the take-up roller 6, the birefringence of the taken yarn is 25×10 ^-3 or more, preferably 30×.
Set it so that it becomes 10 ^-3 to 45×10 ^-3 . The drawing speed corresponding to the birefringence is usually 2000 m/min or more, preferably 2500 to 6000 m/min. If the birefringence of the undrawn yarn is less than 25×10 ^-3 , the properties intended by the present invention, namely, the dry heat shrinkage rate of 4% or less and the degree of amorphous molecular orientation of 0.70 or less cannot be obtained. The desired effect, namely nylon 66 fiber with excellent dimensional stability and fatigue resistance, cannot be obtained. On the other hand, the drawn yarn obtained with birefringence exceeding approximately 45×10 ^-3 is stable.
It cannot be made into a high tenacity yarn with a strength of 7.5g/d or more. In the method for obtaining fibers according to the present invention, 2000
In order to stably and continuously maintain high-speed spinning of m/min or higher, the temperature of the atmosphere 2 directly below the spinneret 1 is extremely important. This refers to the area surrounded by the atmosphere 2 and the lower surface of the base 1 by the heating cylinder 3, which will be described later. For example, in order to maintain the yarn spun from the spinneret at the melting temperature of the polymer in an area at least 10 cm from the spinneret surface, a heating cylinder 3
Set up. The heating cylinder 3 is heated above the melting point of the polymer, and the atmosphere 2 at least 10 cm from the mouth surface is
The temperature should be 250℃ or higher, usually 270-350℃. The length L and inner diameter D of the heating cylinder 3 are, for example, L = 0.1 to 1 m, D = 0.05 to 0.5 m, and
L/D≧0.2. A cooling device 4 is provided below the heating cylinder 3 with or without a heat insulating region to cool the spun yarn Y. There are various types of cooling device 4, such as uniflow type, annular natural suction type, and annular blowout type.
A method suitable for the present invention is an annular blowing method that facilitates uniform cooling. This approach is illustrated in FIG. 2, which is a cross-sectional view of FIG. The spun yarn Y, which has been cooled and solidified, is applied with a lubricant by an ordinary lubricating device 5, ie, a lubricating roll or a guide lubricating device, and then taken up by a pair of take-up rolls, for example, Nelson rolls 6. By the way, the spinning speed of nylon 66 fiber is approximately 1500.
In the range where the molecular chains reach the intermediate orientation region at m/min or more and less than 3500 m/min, crystallization occurs due to water absorption and moisture absorption during winding, resulting in significant vertical swelling, making normal winding impossible. . Therefore, in the method for obtaining fibers according to the present invention, when the spinning speed is 2000 m/min or more and less than 3500 m/min, the spun yarn is transferred to the take-up roll 6.
After taking it off, it is continuously stretched by 2.0 times or less between a stretching roll 7 and then rolled up. At this time, the temperature of the take-up roll 6 is below 120℃, usually 80℃.
Heating at a temperature below ℃ or no heating. As the stretching roll 7, it is preferable to use a heated roll heated to room temperature to 150°C, preferably 60 to 120°C. On the other hand, in the case of a spinning speed of 4000 m/min or more, the shrinkage rate of the yarn during winding is large, which tends to crush the paper tube and break the end surface of the winding drum. The above-mentioned stretching roll 7 is used at a lower speed than the take-up roll 6, and is used at a speed of 20% or less, usually 10%
Roll it up while giving the following relaxation. In this case, both the take-up roll and the stretching roll may be kept at room temperature. The take-up chamber and drawing chamber where the rolls are installed are preferably relatively low-humidity, e.g.
A room controlled at ℃ and 40% RH is used. In order to stably obtain nylon 66 fibers, a multi-stage drawing method is preferred as the drawing method, but since the drawn yarn 8' already has a relatively high degree of orientation, the total drawing ratio is 3.5.
It is possible to adopt a single-stage stretching method of 3.0 to 1.4 times or less, usually 3.0 to 1.4 times. In order to obtain high-strength yarn, it is drawn at a high draw ratio of 80% or more of the maximum draw ratio, and the residual elongation is 15 to 30%. It is basically determined by the degree of
Note that the maximum stretching ratio refers to the maximum stretching ratio that can be stretched. An example of a drawing method for obtaining fibers according to the invention is shown in FIG. Specifically, it is as follows. 1FR (1st feed roll) 9 is 60
It is used at temperatures below ℃, usually room temperature. 2FR
(Second feed roll) 10 is room temperature to 90℃, 1DR
(First draw roll) 11 is 80-150℃, HP (hot plate) 12 is 150-240℃, 2DR (second draw roll) 13 is below the melting point of nylon 66, usually 160-240℃
Each is set to a temperature of 240° C., which is equal to or higher than the temperature of the rolls placed in the previous stage. The temperature of the last placed RR (tension adjustment roll) 14 is 220°C or less. The stretching ratio between 1FR9 and 2FR10 is set in a range of 1.00 to 1.10 where no substantial stretching occurs. 1FR
9 may be replaced by an appropriate tensor and may not be used. The yarn is 2FR10~1DR1
Between 1 is 1.3 to 2.0 times, between 1DR11 and 2DR13 is 1.2 to
Stretched at 2.0 times, 2DR13~RR14 is 0.85~
Subject to limited contraction in the range of 1.00. In addition, when adopting the one-stage stretching method, 1DR1
However, in this case, the installation of 1FR9 is particularly advantageous for obtaining the fiber targeted by the present invention. The tension adjustment zone between 2DR13 and RR14 is particularly important in the process of high-strength stretching, and by installing this zone, the stretching ratio in the previous stage can be set sufficiently high within the allowable range of stretchability. I can do it. 15% contraction between 2DR13 and RR14
If the stretching exceeds 2DR, the degree of crystal orientation of the nylon 66 fibers achieved by drawing up to 2DR13 will decrease, making it impossible to obtain sufficient strength and initial modulus. In addition, in the method for obtaining fibers according to the method of the present invention,
A spun yarn Y is produced by the method shown in FIG. 1, and then spun yarn Y is produced by the method shown in FIG.
It is also possible to make drawn fibers by a so-called direct spinning/drawing method in which the fibers are drawn continuously without being wound once. This process is an efficient manufacturing method because fibers are spun at high speed and drawn continuously after spinning. This process is shown in FIG. In the direct spinning/drawing method, the process up to the take-up roll 6 is exactly the same as the above method. To show an example of the stretching process, as shown in FIG. 4, the take-up roll 6 is used at a temperature of 60 DEG C. or lower, usually at room temperature. FR (second feed roll) 17 is at room temperature to 90℃,
1DR (first draw roll) 18 is 80-150℃,
The temperature of 2DR (second draw roll) 19 is below the melting point of the polyamide. The temperature of each roll is set to be equal to or higher than the temperature of the roll installed in the previous stage. The temperature of the last installed RR (adjustment roll) 20 is 220℃ or less. The stretching ratio between the take-up roll 6 and the FR 17 is set in a range of 1.0 to 1.10 at which substantially no stretching occurs. FR17 uses take-up roll 6 and 1DR18 to give preliminary stretch when drawing the take-up yarn.
However, by installing this FR17, the drawing of the take-up yarn is carried out smoothly.If the yarn is drawn between the take-up roll 6 and the 1DR18 immediately after being taken off, the yarn on the take-up roll 6 will be stabilized. Otherwise, single yarn breakage occurs during stretching, which induces all yarn breakage, resulting in a decrease in shrinkage rate. Meanwhile 10%
Applying the above stretching results in non-uniform stretching, which is actually more disadvantageous than when FR17 is not installed. In addition, when adopting the one-stage stretching method, 2DR1
However, in this case, the installation of FR17 is particularly preferable to obtain the fiber targeted by the present invention. 1.3 to 2.0 times between FR17 and 1DR18, 1DR18
Between 2DR19 and 2DR19, the yarn is stretched by a factor of 1.2 to 2.0, and between 2DR19 and RR20, the yarn undergoes limited shrinkage in the range of 0.85 to 1.00. The reason and effect of installing the tension adjustment zone between 2DR19 and RR20 are the same as in the method explained using FIGS. 1 and 2 above. Each roll unit is over 2000m/min, maximum 6000m/min
m/min or more, it is preferable to use a Nelson roll unit suitable for high speeds. The winding speed is
6000 m/min or more, so in the method for obtaining fibers according to the present invention, the initial threading is performed at about 4000 m/min, and the rolls and winding machine 8 are gradually increased.
It is advantageous to use a winding machine with an automatic switching device, so that it is possible to switch the bobbin automatically when a predetermined speed is reached. The nylon 66 fiber obtained by the above method has the following characteristics. (B) T/D≧7.5g/d (B) 30≧E≧12% (C) Mi≧28g/d (D) ΔS≦4% (E) fc≧0.92 (F) ≦0.70 In addition, the above ( The definitions and measurement methods of the characteristics (a) to (f) are as follows. (a) Tensile strength T/D, (b) Residual elongation E, (d) Initial modulus Mi: As defined by JIS-L1017. Take the sample into a skein, leave it for 24 hours in a temperature and humidity controlled room at 20℃ and 65% RH, and then test it to a sample length of 25cm using a Tensilon UTM-4L tensile tester [manufactured by Toyo Baldwin Co., Ltd.]. , measured at a tensile speed of 30 cm/min. (c) Dry heat shrinkage rate ΔS: Take the sample in a skein shape, leave it in a temperature- and humidity-controlled room at 20℃ and 65%RH for more than 24 hours, and then
A sample of length l ₀ , measured under a load equivalent to 0.1 g/d, was left in an oven at 177°C for 30 minutes without tension, then removed from the oven and placed in the above temperature-humidity controlled room. Leave it for 24 hours,
The above load was applied again to measure, and the length _l1 was calculated using the following formula. Dry heat shrinkage rate ΔS = (l ₀ − l ₁ )/l ₀ ×100 (%) (e) Crystal orientation fc; using a wide-angle x-ray scattering device manufactured by Rigaku Denki Co., Ltd.
Measurements were made using CuKa as a radiation source. The orientation function fc of the crystal part was determined from the half-width H° of the intensity distribution along the Debye ring of equatorial interference (2.0.0) using the following equation. Degree of crystal orientation fc = 180゜-H/180゜(f) Degree of amorphous molecular orientation; The sample was coated with the fluorescent agent “whitexRP” [manufactured by Sumitomo Chemical Co., Ltd.]
The sample was immersed in a 0.2% by weight aqueous solution at 20°C for 2 hours, thoroughly washed, and air-dried to be used as a measurement sample. Using a FOM-1 polarization photometer manufactured by JASCO Corporation,
The relative intensity of polarized fluorescence was measured and calculated using the following formula. Degree of amorphous molecular orientation = 1-B/A However, A: Relative intensity of polarized fluorescence in the direction of the fiber axis B: Relative intensity in the direction perpendicular to the fiber axis The nylon 66 fiber of the present invention having the above characteristics is different from conventional industrial fibers. It has the following characteristics compared to the nylon 66 fiber used. In other words, the strength of the drawn yarn is approximately 10%.
Although it is low, the initial modulus is the same or even higher, and the dry heat shrinkage rate is extremely low. In terms of fiber structure, compared to conventional yarns, the crystal orientation is slightly higher and the degree of amorphous molecular orientation is considerably lower. In other words, the crystals are highly complete and well oriented, while the intercrystalline amorphous molecular chains are relaxed, and each of the crystals and amorphous parts has a stable structure, resulting in a remarkable two-phase structure. The structure of the nylon 66 fiber of the present invention is significantly different from that which has traditionally been used as a rubber reinforcing fiber. In addition, the characteristics of the fiber structure of the drawn yarn are further enhanced, for example, when the yarn is used as a tire reinforcing fiber, in a higher processing step, particularly in heat setting after applying an adhesive. The treated cord made of the fiber of the present invention, which has a more pronounced two-phase structure, has an extremely low shrinkage rate. If the shrinkage rate is designed to be at the same level as a treated cord made from conventionally known fibers, the stretch during heat setting after applying the adhesive can be greatly increased, resulting in a high modulus cord. At this time, the treated cord of the present invention recovers to a level comparable to cords made of conventional yarn. Further, the high fatigue resistance, which is another feature of the nylon 66 fiber of the present invention, is also due to this low degree of amorphous molecular orientation. As for fatigue resistance, according to the Gutdeyer-Mallory-Juve-Huateiguiyu test according to ASTM-D885, it has a fatigue life that is more than 2.5 times that of conventional polyamide fibers. In order to improve fatigue resistance with conventional yarn, if you try to achieve low amorphous molecular orientation, you need to use low-magnification drawn yarn or
It has been necessary to manufacture cords by highly relaxing them at high temperatures, but these methods inevitably result in cords with low elastic modulus. By using the nylon 66 fiber of the present invention, a treated cord with high elastic modulus, low shrinkage rate, and excellent fatigue resistance can be obtained, and if necessary, it can be designed to be as strong as a cord made of conventional yarn. It is possible. Furthermore, noting that the fatigue resistance of the treated cord made of the fibers of the present invention is extremely excellent, it is also possible to design the cord by reducing the number of twists to maintain the fatigue resistance at the same level as the treated cord made of conventional yarn. be. In this case, not only can the twisting speed be increased and costs can be reduced, but the treated cord has the advantage of having even higher strength, higher elastic modulus, and lower shrinkage rate. What has been desired for a long time has become possible for the first time with the provision of the fiber of the present invention. Bias tires using treated cords manufactured with a reduced number of twists were found to have improved flat spot resistance and improved durability. In addition, when used as a V-belt cord as an example of an application other than a tire cord, it has good dimensional stability during rubber vulcanization.
The yield rate has been greatly improved, and the flexural fatigue life has also been greatly improved. When used as a base fabric for resin coated fabrics, its dimensional stability is exhibited. <Examples> Hereinafter, the present invention will be explained in detail with reference to Examples, but characteristics and measurement methods not mentioned above are as follows. (1) Intermediate elongation (treated cord) ME: Similarly to the above-mentioned T/D, E, and Mi, the elongation at stress of 2.68 g/d was determined in the load-extension curve of the treated cord, and this was determined as the intermediate elongation. (2) Strong utilization rate Strong utilization rate = Processing code strength / Yarn strength × 2 × 100 (
%) Examples 1 to 7 and Comparative Examples 1 to 5 Nylon 66 chips with ηr = 3.2 containing 0.03% by weight of cuprous iodide and 0.06% by weight of potassium iodide were spun using an extruder type spinning machine. The hole diameter of the cap is 0.3
mmφ, the number of holes was 204, and the polymer temperature was 290°C. The atmosphere 15cm below the spindle is the same as the temperature of the spun polymer.
Passed through a heating cylinder kept at 290℃, then 5cm
A 30 cm long annular chimney attached through a long insulation zone cooled the yarn from the periphery with cold air at 25° C. at a wind speed of 50 m/min. The yarn was further cooled by passing through a 4 m duct, and then oiled with an oiling device arranged in two stages. The yarn is then taken up by a Nelson-type take-up roll (6 in Figure 1) that rotates at a predetermined speed, and then immediately wound, or continuously between a drawing roll (7 in Figure 1). In some cases, it may be rolled up after undergoing stretching or relaxation. Table 1 shows the taking-off and stretching conditions and the birefringence index of the wound yarn. The wound yarn was then drawn under the conditions shown in Table 2. On the other hand, after being taken up with a take-up roll, the yarn was drawn continuously under the conditions shown in Table 3 using a direct spinning drawing method to obtain a drawn yarn having a direct residual elongation of 20 to 25% and a density of 840 denier. The drawn yarn properties are summarized in Table 4.

【table】

【table】

【table】

【table】

【table】

【table】

【table】

[Table] Next, twist each drawn yarn in the Z direction.
The first twisted yarn was twisted at 47T/10cm and two yarns were twisted together in the S direction at 47T/10cm to make a raw cord. The raw cord was coated with an adhesive and heat treated using a hot air circulation type dipping m/c manufactured by Ritzler. The adhesive liquid used was a resorcinol-formalin-latex liquid, and the adhesion amount was adjusted to 5%. The drying zone is heated at 150℃ for 130 seconds at a constant length,
The heat treatment zone was treated at 210°C for 50 seconds and subjected to a 10% stretch. The normal zone was treated at 210° C. for 50 seconds while giving 1% relaxation. Table 4 shows the characteristics of the obtained processed code. The treated cord using the fibers of the present invention had a slightly low intermediate elongation, but a low shrinkage rate, and the fatigue resistance was approximately doubled. Examples 9, 10 Raw yarn used in Example 3 (sample nylon 66 fiber
0.3) Raw cords of 42T/10cm and 37T/10cm were made for both the first and second twists, and treated with adhesive and heat treated in the same manner as in Example 3 to obtain treated cords. Table 5 shows a comparison of treated cords with a reduced number of twists (Examples 8 and 9) with cords obtained by the conventional method (Comparative Example 1). Even though the number of twists is greatly reduced, the present invention sample has a GT fatigue life superior to cords obtained by conventional methods, has a strength exceeding that of conventional yarns, and has a characteristic treatment with low intermediate elongation and dry yield. Got the code. <Effects of the Invention> The nylon 66 fiber of the present invention has the following characteristics compared to the nylon 66 fiber used in conventional industrial fibers. That is, the strength of the drawn yarn is about 10% lower, but the initial modulus is the same or even higher, and the dry heat shrinkage rate is extremely low. In terms of fiber structure, compared to conventional yarns, the crystal orientation is slightly higher and the degree of amorphous molecular orientation is considerably lower. In other words, the crystals are highly complete and well oriented, while the intercrystalline amorphous molecular chains are relaxed, and each of the crystals and amorphous parts has a stable structure, resulting in a remarkable two-phase structure. The structure of the nylon 66 fiber of the present invention is significantly different from that which has traditionally been used as a rubber reinforcing fiber. In addition, the characteristics of the fiber structure of the drawn yarn are further enhanced, for example, when the yarn is used as a tire reinforcing fiber, in a higher processing step, particularly in heat setting after applying an adhesive. The treated cord made of the fiber of the present invention, which has a more pronounced two-phase structure, has an extremely low shrinkage rate. If the shrinkage rate is designed to be at the same level as a treated cord made from conventionally known fibers, the stretch during heat setting after applying the adhesive can be greatly increased, resulting in a high modulus cord. At this time, the treated cord of the present invention recovers to a level comparable to cords made of conventional yarn. Further, the high fatigue resistance, which is another feature of the nylon 66 fiber of the present invention, is also due to this low degree of amorphous molecular orientation. As for fatigue resistance, according to the Gutdeyer-Mallory-Juve-Huateiguiyu test according to ASTM-D885, it has a fatigue life that is more than 2.5 times that of conventional polyamide fibers. Conventionally, in order to improve the fatigue resistance of yarns, in order to orient low amorphous molecules, it was necessary to apply low-magnification drawn yarns or to manufacture yarns by highly relaxing them at high temperatures, but with these methods, Inevitably, only a cord with a low elastic modulus could be obtained. Nylon 66 of the present invention
By using fibers, a treated cord with high elastic modulus, low shrinkage rate, and excellent fatigue resistance can be obtained, and if necessary, it can be designed to be as strong as a cord made of conventional yarn. Furthermore, noting that the fatigue resistance of the treated cord made of the fibers of the present invention is extremely excellent, it is also possible to design the cord by reducing the number of twists to maintain the fatigue resistance at the same level as the treated cord made of conventional yarn. be. In this case, not only can the twisting speed be increased and costs can be reduced, but the treated cord has the advantage of having even higher strength, higher elastic modulus, and lower shrinkage rate. Bias tires using treated cords manufactured with a reduced number of twists in this manner were found to have improved flat spot resistance and improved durability. In addition, when used as a V-belt cord as an example of an application other than a tire cord, it has good dimensional stability during rubber vulcanization.
The yield rate has been greatly improved, and the flexural fatigue life has also been greatly improved. When used as a base fabric for resin coated fabrics, its dimensional stability is exhibited.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the spinning process of the present invention. FIG. 2 is a - sectional view in FIG. 1. FIG. 3 is a process diagram showing the same stretching process. FIG. 4 is a process diagram showing another embodiment of the present invention. Y... Spun yarn, 1... Cap, 2... Atmosphere inside the heating cylinder, 3... Heating cylinder, 6... Take-up roll, 7...
...Stretch roll.

Claims (1)

[Scope of Claims] 1. A fiber made of polyhexamethylene adipamide having a hexamethylene adipamide repeating structural unit of 95 mol% or more and a sulfuric acid relative viscosity of 2.8 or more, and having the following properties at the same time: and polyhexamethylene adipamide fibers with significantly improved dimensional stability and fatigue resistance. (a) T/D≧7.5g/d (b) 30≧E≧12% (c) Mi≧28g/d (d) ΔS≦4% (e) fc≧0.92 (f) ≦0.70 In addition, in the above T/D is the strength, E is the residual elongation, Mi is the initial modulus, ΔS is the dry heat shrinkage rate at 177°C, fc is the degree of crystal orientation, and is the degree of amorphous molecular orientation.