JPH0350003B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-strength polyethylene terephthalate yarn that is useful as an industrial material, and particularly to a polyethylene terephthalate yarn that has high strength and excellent mechanical fatigue properties and is useful as a tire cord. Polyethylene terephthalate yarn has a high initial modulus, good dimensional stability, and satisfies the required characteristics as a carcass material for radial tires for automobiles, so its usage has been increasing recently. High-strength polyethylene terephthalate yarn is produced by melt-spinning high molecular weight polyethylene terephthalate and then using a heating cylinder at a temperature of about 270°C or higher, preferably about 300°C or higher, as typified by, for example, Japanese Patent Publication No. 7892/1973. Perform delayed cooling to 3×10 ^-3 or less,
Preferably, it can be produced by controlling the spinning tension to give an extremely small molecular orientation corresponding to an optical birefringence of 2×10 ^-3 or less, and then stretching by a factor of 5.7 or more, and that it can be produced in this way. It is known that the yarn to be used is a high-strength filament having characteristics as disclosed in, for example, Japanese Patent Publication No. 53-1367. On the other hand, high-strength polyethylene terephthalate yarn having the characteristics described in Japanese Patent Publication No. 53-1367, which is obtained by the method described in Japanese Patent Publication No. 41-7892 mentioned above, is disclosed in Japanese Patent Application Laid-Open No. 53-58031. As mentioned in , the hysteresis loss (hereinafter referred to as ``work loss'') is large, and as the tire rotates, the polyethylene terephthalate cord that acts as a fibrous reinforcement generates heat, significantly shortening the tire life. is also publicly known. For example, in Japanese Patent Application Laid-Open No. 53-58031,
JP-A No. 1367 discloses a high-strength polyester yarn that improves the defects of the polyethylene terephthalate yarn and has a significantly stable internal structure with less work loss.
Publication No. 58032 describes a method for producing such yarn. The outline of the method disclosed in JP-A No. 53-58032 is to melt-spun polyester and then uniformly rapidly cool it through a curing zone so that it has a relatively high birefringence of 9 x 10 ^-3 to 70 x 10 ^-3 . The goal is to control the yarn tension and then draw it. However, JP-A-53-58031 and JP-A-Sho
As described in the Examples of Publication No. 53-58032,
The strength of the yarn obtained by such highly oriented spinning is
It is about 7.3 to 9.1 g/d, which is not necessarily high. Even after additional tests by the present inventors, it was difficult to obtain a yarn with sufficient strength. The present inventors have developed yarns with high strength and small work loss (i.e.,
While conducting intensive research in an effort to obtain polyethylene terephthalate yarn with excellent mechanical fatigue resistance, we found that by creating a yarn with a special combination of structural requirements, including specifying the intrinsic viscosity of the yarn, we were able to overcome the conventional technology described above. The present inventors have discovered that these defects can be overcome and characteristics particularly useful as a tire cord can be obtained, and have completed the present invention. The high-strength polyethylene terephthalate multifilament yarn according to the present invention has (a) intrinsic viscosity: 0.60 to 0.80, (b) strength: 8.0 to 10.0 g/d, elongation: 11% or more, and (c) birefringence. : 0.180 to 0.205, (d) Shrinkage measured at 175℃ in air: 7.5 to 9.5% (e) When repeated cycles of expansion and relaxation with stress between 0.60 g/d and 0.05 g/d, 1000 Work loss at 150°C measured at a strain rate of 1 cm/min on a 25 cm length of yarn standardized to a total denier multifilament yarn: 0.030 to
0.060Kg・cm, (F) If the cycle of stretching and relaxation is repeated with a stress between 0.60g/d and 0.05g/d, 1000
Strain rate 1.27 for 25.4 cm long yarn standardized to full denier multifilament yarn
Work loss (Kg cm) at 150°C measured in cm/min
Stability coefficient obtained by multiplying by the shrinkage (%) measured in air at 175°C and taking the reciprocal of the product: 1.7 to 4.5, and (g) The multifilament is pre-twisted with a twisting coefficient of 15800. This pre-twisted cord 2
The book is given the same number of ply twists as the ply twists and in the opposite direction to form a ply-twisted cord, and this ply-twisted cord has 0.18 g/d.
95 on a hot plate heated to 220℃ while applying a tension of
When the model code is heat-set for seconds and subjected to repeated cycles of stretching and relaxation at a stress between 0.60 g/d and 0.05 g/d, it is standardized to a multifilament yarn of 1000 total denier. Work loss at 150℃ measured on a 25cm long yarn at a strain rate of 1cm/min:
This is a high-strength polyethylene terephthalate multifilament yarn that satisfies all the characteristics of 0.015 to 0.040 kg/cm. This clever combination of construction requirements makes it possible for the first time to obtain a cord that has both high strength and low work loss properties, which are particularly useful as tire cords. In order to make it easier to understand the difference between the yarn of the present invention and the conventional yarn, comparative data is shown in Table 1. In Table 1, conventional yarn (1) refers to
It is a high-strength polyester yarn having a significantly stable internal structure as described in Japanese Patent Application Laid-open No. 53-58032, and the conventional yarn (2) is
Yarns referred to as "conventional threads" in JP-A No. 58031 and JP-A-53-58032, namely, JP-A-41-7892 and JP-A-Sho. 53-
This is a conventional yarn as exemplified in Japanese Patent No. 1397.

[Kg・cm/cycle/1000 denier・25cm]

Where, Wt _C = Weight of cut curve [g] FSL = Full scale load [Kg] CHS = Crosshead speed [cm/min] Wt _T = Weight of paper area generated in 1 minute due to full scale load [g] W=work loss. The work loss of the yarn determined as described above is required to be 0.030 to 0.060 Kg·cm for the yarn of the present invention. If the value is less than the lower limit of this range, it will be difficult to industrially produce yarn with sufficient strength, and if it is greater than the upper limit of this range, it will be difficult to manufacture tire cords with low work loss. Can not. The above work loss of the present application is 0.030 to 0.060.
The value of Kg·cm can be obtained by combining the above manufacturing conditions. Generally, in order to use raw yarn for tire cord as a tire cord, the cord obtained by adding first twist and second twist to the raw tire cord yarn is dried, heat set, and normalized after dipping to make it into a tire cord. Eggplant (for example, "Rubber Industry Handbook <New Edition>" pages 542-543 (Japan Rubber Association, 1978)). As a model evaluation method for this tire cord, it has been proposed to evaluate a model cord obtained by heating and stretching a cord that has been twisted and twisted (for example, Japanese Patent Publication No. 51-7892, p. 5). (Right column, lines 22 to 27). The present inventors conducted the model code evaluation described below in accordance with this known model code evaluation method. This model code and
Drying temperature 160 using Litsler Computreter
The correlation coefficient of work loss with the dark processed code obtained at a heat setting temperature of 245°C, a normalizing temperature of 245°C, and a processing time of 60 seconds was good at 0.97. A first twist is applied to the multifilament with a twist coefficient of 15800 to create a first twisted cord, and two first twisted cords are given the same number of twists as the first twist in the opposite direction to form a second twisted cord, and this first twisted cord is 0.18. The work loss of a model cord obtained by heat setting on a hot plate heated to 220° C. for 95 seconds while applying a tension of g/d can also be determined in the same manner as the work loss of a multifilament yarn. Here, the twist coefficient is K in the following formula, where the total denier is D and the number of twists is T [times/m].
is required. K=T×√ For example, total denier 1000, twist coefficient
When the number of twists is 15800, the number of twists T is 500 times/m. The work loss of the twisted cord obtained in this way is 0.015
It is necessary to set it to 0.040Kg・cm. Cords that are less than the lower end of this range and have high strength are
It is difficult to produce industrially, and conversely,
If it is larger than the upper limit of this range, the work loss of the tire cord will become large and the mechanical fatigue properties will deteriorate rapidly. Work loss of the above model code of this application is 0.015
A value of 0.040 Kg·cm can be obtained by combining the above manufacturing conditions. The stability coefficient is 0.60 in the shrinkage (%) of the multifilament yarn measured at 175°C in air as described above.
150 measured at a strain rate of 1 cm/min on a 25 cm length of yarn standardized to 1000 total denier multifilament yarn when repeated cycles of elongation relaxation at stresses between 0.05 g/d and 0.05 g/d. Work loss of multifilament yarn at °C (Kg・cm)
It is found by multiplying by and taking the reciprocal of the product. In the yarn of the present invention, it is necessary to set it to 1.7 to 4.5. If the value is less than the lower limit of this range, it will be difficult to produce yarn with good mechanical fatigue resistance, and conversely, if it is greater than the upper limit of this range, it will be difficult to produce yarn with sufficient strength industrially. cannot be manufactured. The stability coefficient values of 1.7 to 4.5 in this application are:
It can be obtained by combining the above manufacturing conditions. As specified in the claims and detailed above, the yarn of the present invention skillfully combines the constituent features (a) to (g) above and has all of them. Unexpectedly, when this yarn is dip-treated and made into a tire cord, the work loss is further reduced to 0.013 to 0.030, and it has good mechanical fatigue resistance and high strength. It can be a code. In order to manufacture the yarn of the present invention, for example, the method for manufacturing high-strength polyethylene terephthalate yarn (Unexamined Japanese Patent Publication No. 58-1989), which was filed on the same day as the present application, is required.
98417) is preferred. The outline of this manufacturing method will be explained below. That is, the method for producing the above-mentioned high-strength polyethylene terephthalate yarn is as follows: (a) Polyethylene terephthalate having an intrinsic viscosity of 0.60 to 0.85 is continuously spun through a spinneret with multiple holes in a molten state at 280 to 310°C to form a molten mulch. (b) The molten multifilament is passed through a heat-retaining area with a length of 20 to 80 cm maintained at an ambient temperature of 80 to 200°C provided directly below the spinneret to suppress rapid cooling, (c) The molten multifilament that has passed through this heat retention area is rapidly cooled and turned into a solid multifilament.
Take-off birefringence +3 at take-off speed of m/min
×10 ^-3 to +8 × 10 ^-3 finely oriented multifilament. A first stage drawing of 1.10 times is carried out, and then multi-stage drawing is carried out using a pair of godet rolls heated at 20 to 140°C to a total drawing ratio of 4.3 to 6.2 times, and then (f) this drawn multifilament is stretched at 200°C to 245°C.
This is a method for producing high-strength polyethylene terephthalate yarn, which is characterized by continuous heat treatment and winding at °C without shrinkage. In order to make it easier to understand the difference between the method for producing the yarn of the present invention and the conventional method, comparative data is shown in Table 2. In Table 2, conventional method (1) is the method described in Japanese Patent Application Publication No. 53-58032, and conventional method (2) is the method described in Japanese Patent Publication No. 41-7892. be.

[Table] Next, the method for producing the unique high-strength polyethylene terephthalate yarn of the present invention will be described in detail and specifically with reference to the drawings. FIG. 1 shows a layout of equipment suitable for carrying out the manufacturing method. Polyethylene terephthalate having an intrinsic viscosity of 0.60 to 0.85 is continuously spun in a molten state through a spinneret 1 having multiple holes to form a molten multifilament. This molten multifilament is passed through a heat-retaining area having an atmospheric temperature of 80 to 200°C and a length of 20 to 80 cm formed by a heat-retaining cylinder 2 provided directly below the spinneret 1 to suppress rapid cooling. The heat retaining cylinder 2 is usually formed by providing a heat retaining wall made of asbestos board, asbestos, etc. on the outside of an inner cylinder having high thermal conductivity such as aluminum or brass. Normally, the ambient temperature in the heat retention area 3 is 80 to 200 degrees Celsius due to heat radiation from the spinneret, molten multifilament, etc. without any special heating.
is maintained. For example, aluminum length 50
When spinning is carried out at a spinning temperature of 290°C using a cm heat-retaining cylinder, the atmospheric temperature within the heat-retaining area 3 can be maintained at 130°C. In this way, the ambient temperature in the heat-retaining area 3 can be changed by changing the spinning temperature and the length of the heat-retaining tube, but if necessary, the ambient temperature can be further adjusted by burying cold water pipes, heaters, etc. It's okay. When the ambient temperature is lower than 80° C. or when the length of the heat retention region is shorter than 20 cm, the birefringence of the multifilament drawn by the godet roll pair 6 tends to be excessive. On the other hand, when the ambient temperature is higher than 200° C. or when the length of the heat-retaining region is longer than 80 cm, the birefringence of the multifilament drawn by the godet roll pair 6 tends to be too small. The above-mentioned melt spinning conditions are such that when producing conventional high-strength yarn, the ambient temperature is set to 270°C using a 30 to 120cm heating cylinder.
℃ or higher, preferably 300℃ or higher, and especially in the case of highly oriented spinning, the temperature is 10 to 60℃ directly below the spinneret.
This is in sharp contrast to the previous method of quenching using cold air. The molten multifilament that has passed through the heat retention area 3 is then rapidly cooled by cold air at about 20°C blown from the spinning tower 4 to turn it into a solid multifilament, and after being applied with a spinning finisher by an oiling roll 5, it is spun at 500 to 1500 m/min. The first godet roll pair 6 at room temperature (approximately 20°C) rotates at a speed of
A finely oriented filament with a birefringence of +3×10 ^-3 to +8×10 ^-3 is formed. At this stage, the birefringence is +3×
If it is smaller than 10 ^-3 , the work loss of the yarn obtained after drawing becomes large, and conversely, the birefringence becomes +8
When it is larger than ×10 ⁻³ , the strength and elongation of the drawn yarn tend to be low. The finely oriented multifilament taken up by the first godet roll pair 6 is stretched in multiple stages between the subsequent godet roll pair groups 7, 8, and 9 without being wound up at one end. Preferably, the temperature of the second pair of godets should be between 90 and 110°C, and the temperature of the third pair of godets should be between 120 and 140°C. By using such temperature conditions, the total stretching ratio is 4.3 to 6.2.
can be achieved. Note that one of the two rolls of the godet roll pair may be a passively driven roll such as a separate roll. If the total draw ratio is smaller than 4.3, it will not be possible to obtain a yarn with sufficient strength, and if it is larger than 6.2, the elongation will be poor.
The yarn is smaller than 11%, and the yarn is frequently cut, making it impossible to manufacture the yarn on an industrial scale. Here, the "total drawing ratio" refers to the ratio of the surface speeds of the fourth godet roll pair 9 and the first godet roll pair 6. The multifilament yarn drawn in multiple stages is then heat-treated with a fourth godet roll 9 heated to 200 to 245°C, and wound up as a product package 11. This heat treatment tends to reduce the drying shrinkage rate of the multifilament yarn as well as the work loss of the yarn. As specified in the claims and detailed above, the yarn of the present invention skillfully combines the components (a) to (g) and has all of them. And, quite unexpectedly, when this yarn is dip-treated and made into a tire cord, the work loss is 0.013 to 0.013 compared to the original yarn.
It is further reduced specifically to 0.030Kg・cm, making it possible to create a cord with good mechanical fatigue resistance and high strength. Next, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples. Example 1 A 1000 ^d /384 ^f polyethylene terephthalate yarn for tire cords was obtained by a direct spinning drawing heat treatment method using the apparatus shown in FIG. That is,
Using a spinneret 1 having 384 spinning holes, molten polyethylene terephthalate having an intrinsic viscosity of 0.70 was spun at a spinning temperature of 290°C, and passed through an atmosphere 3 kept at 130°C by a heat-insulating tube 2 with a length of 50 cm. After being cooled and solidified by cold air at 20°C blown out from the spinning tower 4 and applying a spinning finishing agent with an oiling roll 5, it is taken up by a pair of first godet rolls 6 at room temperature (20°C) rotating at 670 m/min, and one end is wound. Immediately and continuously heated to 100 ° C., the second godet roll pair 7 was stretched to 1.01 times, and then continuously heated to 130 ° C. The third godet roll pair 8 was stretched to 4.44 times. between the 4th godet roll and 9 heated at 240℃ at 4000m/min.
Stretched 1.34 times, total stretching ratio 6.01 times,
It was heat treated with Godetstrol pair 9 and wound up. The obtained yarn has an intrinsic viscosity of 0.68 and a strength of 9.65 g/
d, elongation 11.4%, birefringence 0.195, 175°C dry heat shrinkage 8.7%, 150°C work loss 0.055 kg·cm, and stability coefficient 2.1. Using a ring twisting machine, this yarn is subjected to S-twisting at 500 times/m to create a pre-twisted cord, and these two pre-twisted cords are then subjected to Z-twisting at 500 times/m to create a 2220d ply-twisted cord. Ivy. This ply-twisted cord was subjected to tension heat treatment using the apparatus shown in FIG. 2 to create a model cord.
That is, from the supply roll 12 to the twisted cord 13
was pulled out, slid on the hot plate 14, and taken off with a take-up roll 17. In FIG. 2, all 15 are free rolls. Here the temperature of the hot plate is 220
℃, and the heat treatment time was 95 seconds. Load 800g
Using a 16-piece heavy peg, apply a tension of 400 to the cord being processed.
gave g. The work loss for this model code is
It decreased significantly to 0.033Kg・cm. Furthermore, add the above twisted cord to Litzler.
I created a dip code using Computreter. The strength of the obtained dip cord is 7.0 g/d,
Work loss was further significantly reduced to 0.020Kg・cm. This dip code is JIS L-1017 1.3.2.1A
A tube fatigue test was conducted in accordance with the law. Goodyear
Using a type testing machine, a rubber tube in which dip cords were buried concentrically was bent at a 95° angle and tested at 3.5 kg/
Apply an internal pressure of ^cm2・G and rotate the tube at 850 rpm.
The tube was rotated at the same time as the tube, and the time until the tube burst due to fatigue of the dip cord was measured. the result,
The average tube rupture time was 660 minutes. Example 2 The intrinsic viscosity of polyethylene terephthalate polymer was 0.62, the spinning temperature was 283°C, and the temperature of the insulation cylinder was 120°C.
℃, the speed of the first Gotetstrol pair is 672 m/min,
The stretching ratio between the second godet roll pair and the third godet roll pair is 3.93, and the stretching ratio between the third godet roll pair and the fourth godet roll pair is 1.50.
The same method as in Example 1 was repeated except that the total stretching ratio was 5.95, and the intrinsic viscosity was 0.61, the strength was 8.73 g/d, and the elongation was
11.1%, birefringence 0.202, 175℃ dry heat shrinkage 7.2%,
A multifilament yarn with a work loss of 0.037 Kg·cm at 150°C and a stability coefficient of 3.8 was obtained. The work loss of the model cord is 0.021Kg・cm, and the strength of the dip cord is
The tube rupture time was 6.6 g/d, the work loss was 0.016 Kg·cm, and the average tube rupture time was 850 minutes. Example 3 The intrinsic viscosity of polyethylene terephthalate polymer was 0.80, the spinning temperature was 300°C, and the temperature of the insulation cylinder was 140.
℃, the speed of the first godettrol pair is 603 m/min,
The stretching ratio between the second godet roll pair and the third godet roll pair is 4.42, the stretching ratio between the third godet roll pair and the fourth godet roll pair is 1.33,
The same method as in Example 1 was repeated except that the total stretching ratio was 5.94, and the intrinsic viscosity was 0.78, the strength was 9.93 g/d, and the elongation was
12.4%, birefringence 0.198, 175℃ dry heat shrinkage 9.4%,
A multifilament yarn with a work loss of 0.058 at 150°C and a stability coefficient of 1.8 was obtained. The work loss of the model cord is 0.037Kg・cm, and the strength of the deep cord is 7.2g/cm.
d. The work loss was 0.025 kg·cm, and the average tube rupture time was 610 minutes. Example 4 The intrinsic viscosity of polyethylene terephthalate polymer was 0.61, the spinning temperature was 283°C, and the temperature of the insulation cylinder was 120°C.
℃, the speed of the first godettrol pair is 1.351 m/min,
The stretching ratio between the second godet roll pair and the third godet roll pair is 2.32, and the stretching ratio between the third godet roll pair and the fourth godet roll pair is 1.45.
The same method as in Example 1 was repeated except that the total stretching ratio was 3.70, and the intrinsic viscosity was 0.60, the strength was 8.24 g/d, and the elongation was
11.9%, birefringence 0.186, 175℃ dry heat shrinkage 6.9%,
A multifilament yarn with a work loss of 0.032 Kg·cm at 150°C and a calculated stability of 4.5 was obtained. The work loss of the model cord is 0.018Kg・cm, and the strength of the dip cord is
The tube rupture time was 6.5 g/d, the work loss was 0.013 Kg·cm, and the average tube rupture time was 950 minutes. Comparative Example 1 When polyethylene terephthalate polymer had an intrinsic viscosity of 0.95 and an attempt was made to manufacture a multifilament yarn using a method similar to Example 1, the total drawing ratio could not be increased to 5.3 times or more, and the yarn The strength remained at 7.02 g/d. Comparative Example 2 According to the method described in Japanese Patent Publication No. 41-7892, a polyethylene terephthalate polymer with an intrinsic viscosity of 0.95 was spun at a spinning temperature of 310°C, and the mixture was placed in a 50cm long heating cylinder heated to an ambient temperature of 400°C. 393 to relax the orientation through the 393
It was taken up using the first godet roll pair at m/min and continuously stretched at a total extension of 6.1 times to 2400 m/min.
I rolled it up in minutes. The intrinsic viscosity of the obtained yarn is
0.91, strength 10.5g/d, elongation 13.2%, birefringence
0.204, 175℃ dry heat shrinkage rate 12.2%, 15℃ work loss
A yarn of 0.095 Kg·cm and a stability coefficient of 0.9 was obtained. Although the work loss of the model cord is 0.052Kg・cm and the strength of the deep cord is 7.4g/d, the work loss is
High at 0.041Kg・cm, average tube rupture time is 124
It was only a minute. Comparative Example 3 Polyethylene terephthalate having an intrinsic viscosity of 0.95 was spun at a spinning temperature of 310°C in accordance with the method described in JP-A No. 53-59032, and quenched with cold air directly below the spinneret, and the rest was carried out in accordance with Example 1. , 1500m/
It was taken up using the first pair of godet rolls at a rate of 3,525 m/min, continuously extended to a total extension ratio of 2.35 times, and wound at a speed of 3525 m/min. The obtained yarn has an intrinsic viscosity of 0.91 and a strength of
A yarn with an elongation of 7.85 g/d, an elongation of 8.2%, a birefringence of 0.182, a dry heat shrinkage rate of 175°C of 6.1%, a work loss of 150°C of 0.016, and a stability coefficient of 8.2 was obtained. Model code work loss
0.014Kg・cm, deep cord strength 6.1g/d,
Work loss 0.013Kg・cm, average tube rupture time 990
Although the mechanical fatigue resistance is good, the strength is low.
Moreover, there was no observed phenomenon in which the work loss of the original multifilament, which is characteristic of the present invention, decreases significantly from the work loss of the dip cord. As detailed above, the yarn of the present invention, which skillfully combines specific structural requirements, has a specific reduction in work loss when processed as a tire cord material, high strength, and mechanical fatigue resistance. It can be a good tire cord. Comparative Example 4 Polyethylene terephthalate having an intrinsic viscosity of 0.65 was spun at a spinning temperature of 290°C according to the method described in JP-A No. 53-58028, and the material was spun in an atmosphere kept at 210°C using a 20cm long heat-insulating tube. Pass, 20
After cooling and solidifying by blowing cold air at a temperature of 8×10 ^-3 Nm ³ /min per 1 g of spinning amount, and applying a finishing agent with an oiling roll, 450 m /
It is picked up by the first pair of godet trolls that rotate in minutes,
Immediately without winding up, the second godet roll pair was preheated at a speed of 420 m/min and 95°C, and then stretched 3.6 times between the third godet roll pair that was continuously heated to 160°C. Then, it was stretched 1.67 times (total extension ratio 6.0 times) using the fourth pair of godet rolls with a surface temperature of 200°C, and then stretched to 2520 m/
I turned it over at a speed of 1 minute. The obtained yarn has an intrinsic viscosity of 0.63 and a strength of 8.70 g/
d, elongation 10.8%, birefringence 0.201, 175°C dry heat shrinkage 9.3%, 150°C work loss 0.073 Kg·cm, and stability coefficient 1.47. Furthermore, the work loss of the model code is 0.043Kg・cm,
Deep cord strength 6.6g/d, work loss 0.034
kg・cm, and the tube rupture time was as short as 298 minutes.

[Brief explanation of drawings]

FIG. 1 is a layout diagram of a typical apparatus for manufacturing high-strength polyethylene terephthalate yarn by the method of the present invention, and FIG. 2 is a layout diagram of a typical apparatus for manufacturing model cord. DESCRIPTION OF SYMBOLS 1... Spinneret, 2... Heat insulation tube, 4... Spinning tower, 5... Oiling roll, 6-9... Godet roll pair group, 10... Multifilament yarn, 11... Winding package, 12... ... Supply roll, 13 ... Twisted cord, 14 ... Hot plate, 15 ...
Free roll, 16...load, 17...take-up roll.

Claims (1)

[Claims] 1. A high-strength polyethylene terephthalate multifilament yarn characterized by satisfying all of the following characteristics (a) to (g). (i) Intrinsic viscosity: 0.60 to 0.80, (b) Strength: 8.0 to 10.0 g/d, elongation: 11% or more, (c) Birefringence: 0.180 to 0.205, (d) Measured in air at 175°C Shrinkage: 7.5 to 9.5%, (e) When repeated cycles of stretching and relaxing at stresses between 0.60 g/d and 0.05 g/d, a 25 cm length standardized to 1000 total denier multifilament yarn Work loss at 150°C measured on yarn at a strain rate of 1 cm/min: 0.030 to
0.060Kg・cm, (f) When repeated cycles of stretching and relaxation at a stress between 0.60g/d and 0.05g/d, a 25cm length of yarn standardized to 1000 total denier multifilament yarn Stability determined by taking the reciprocal of the product obtained by multiplying the work loss (Kg cm) at 150°C measured at a strain rate of 1 cm/min by the shrinkage (%) measured at 175°C in air. Coefficient: 1.7 to 4.5, and (g) The multifilament is first twisted with a twist coefficient of 15800 to make a first twisted cord, and this first twisted cord 2
The book is given the same number of ply twists as the ply twists and in the opposite direction to form a ply-twisted cord, and this ply-twisted cord has 0.18 g/d.
95 on a hot plate heated to 220℃ while applying a tension of
When the model code is heat-set for seconds and subjected to repeated cycles of stretching and relaxation at a stress between 0.60 g/d and 0.05 g/d, it is standardized to a multifilament yarn of 1000 total denier. Work loss at 150℃ measured on a 25cm long yarn at a strain rate of 1cm/min:
0.015 to 0.040Kg・cm.