JPH0549847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to flat belts and V-belts such as conveyor belts used in industrial machines. Traditionally, belts of this type have been made with a filament fabric made of synthetic fibers such as aliphatic polyamide, polyethylene terephthalate, or polyvinyl alcohol, and coated with abrasion-resistant rubber or flexible resin. , strong, elongation,
It is hard to say that it is sufficient in terms of chemical resistance, etc. That is, the properties required for flat belts, V-belts, etc. are high strength, low elongation, dimensional stability, and chemical resistance. It goes without saying that high strength is required, and at the same time, moderately low elongation is also required. If the elongation is too high, the belt will sag over time. If the elongation is extremely low, it will be difficult to apply sufficient tension to the belt. To manufacture a high-strength belt, thick denier yarns can be used as warp yarns, but this increases the weight and thickness, which is undesirable in terms of transportation and handling. In order to solve these problems,
In Publication No. 120775, a twisted yarn consisting of fibers mainly composed of polyparaphenylene terephthalamide and fibers mainly composed of polymetaphenylene isophthalamide is used for the warp, and a fiber mainly composed of polymethaphenylene isophthalamide is used as the weft. Belts made of belts have been proposed, but when used for a long period of time, there are problems with abrasion resistance, and the belt wears out at the contact surface between the belt and the belt drive unit, and the strength of the belt gradually decreases. . This is because polyparaphenylene terephthalamide fibers are composed of rigid polymer chains and have low abrasion resistance. On the other hand, in Japanese Utility Model Application Publication No. 52-120774, a core spun yarn consisting of a metal fiber as a core and a wholly aromatic polyamide fiber surrounding the core is used as the warp, and a wholly aromatic polyamide fiber is used as the weft. A woven belt is also provided, but in this case, if the wholly aromatic polyamide fiber is polyparaphenylene terephthalamide fiber, it has the same drawbacks regarding abrasion resistance as described above. Additionally, belts used in industrial machinery may become wet due to various chemicals depending on the industrial field, the most commonly used being acids such as sulfuric acid or alkalis such as caustic soda. In such cases, it has been found that the strength of the polyparaphenylene terephthalamide fibers rapidly decreases due to corrosion by acids, alkalis, etc., and the abrasion resistance significantly decreases. Under these circumstances, the present inventors have developed a belt structure that has high strength and appropriate elongation, resists corrosion by acids and alkalis, and has excellent abrasion resistance and dimensional stability. As a result of intensive research, the present invention was arrived at. That is, the present invention provides a belt having excellent strength, which is made by coating a base fabric made of polyester fiber dip cord with high strength and excellent fatigue resistance with rubber or flexible resin on one or both sides. The purpose is to On the other hand, as a method to improve the dimensional stability without reducing the polymerization degree of the polymer, there is a method of stretching POY as seen in USP4195032.
Toughness is sacrificed in order to improve dimensional stability. Furthermore, Japanese Patent Application Laid-open No. 136852/1985 is known as a method for improving dimensional stability in the same way, but in this example as well, similar to the prior art described above, ,
Toughness is sacrificed to improve dimensional stability. According to these conventional techniques, although it is possible to increase the strength retention rate by lowering the twist coefficient, the fatigue resistance is significantly lowered and the cord cannot be used as a rubber reinforcing cord. In order to reduce the shrinkage rate of dip cord,
This can be achieved to some extent by mildly hot-stretching during the dip treatment, but in this case, the low intermediate elongation (high modulus of elasticity) necessary for rubber reinforcing fibers cannot be obtained. As described above, it has been thought that it is extremely difficult to obtain a belt using a dip cord that has high strength, high modulus, and excellent dimensional stability. In view of this current situation, the present inventors have developed a polyester dip cord that has excellent strength, high modulus, and excellent dimensional stability.It also has excellent fatigue resistance. In order to obtain a suitable belt, we carried out intensive research. As a result, by twisting fibers with high strength and high elastic modulus with significantly oriented molecular chains at the raw yarn level and a relatively low number of twists, and performing dip treatment under relatively mild conditions, the above-mentioned results can be obtained. The inventors have revealed that it is possible to obtain a belt with excellent performance, and have arrived at the present invention. In other words, the above objectives are (1) that the repeating structural unit of ethylene terephthalate is
Consisting of 85 mol% or more polyester polymer, with an intrinsic viscosity of 0.80 or more, preferably 0.80 to
Melt spinning polyester having a high degree of polymerization of 1.20; (2) collecting the spun yarn under conditions such that the undrawn yarn has a single filament denier of 30 d or less and a birefringence of 0.002 to 0.010; (3) After the yarn that has passed through the take-up roll is wound continuously or once, it is hot-stretched so that the total stretching ratio is 5.0 times or more, preferably 6.0 times or more; (4) The quality of the drawn yarn is as follows. (a) DT≧9.5g/d, preferably DT≧11.0g/d (b) 12%≧DE≧5%, preferably 10%≧DE≧5% (c) Tα≧160 ℃ More preferably, (d) Birefringence of the fiber △n≧195×10 ^-2 (e) Long period LP by small-angle X-ray diffraction LP≧170Å (f) Single fiber denier of the fiber is 4d or less (5) Stretched yarn (Multifilament yarn) is subjected to first twisting and final twisting with a twist coefficient of 2000 to 1300, preferably 1800 to 1400 to create a raw cord; (6) the raw cord or a blind fabric woven from the raw cord is made into a rubber This is accomplished by a dip treatment followed by a 0-3% hot stretch to improve adhesion to the adhesive. According to this method, a polyester polymer containing 85 mol% or more of ethylene terephthalate repeating structural units has an intrinsic viscosity of 0.80.
It is made of polyester fibers with a high degree of polymerization, and has a twist coefficient of 2000 to 1300, preferably 1800 to 1400, with a dip liquid attached to improve adhesion to rubber. A polyester dip cord having high strength and high modulus and significantly improved dimensional stability and fatigue resistance can be obtained, which has the following properties at the same time. (a) Breaking strength of the dip cord A≧7.5g/d, preferably A≧8.0g/d (b) Intermediate elongation of the dip cord B≦5% (c) Dry heat shrinkage rate of the dip cord C≦5% (d) C ≦-B+8.5 This dip cord is significantly different from conventional polyester dip cords in that it has a low shrinkage rate, high modulus, and high strength. More specifically, the method of the present invention and the characteristics of the fibers obtained by the method will be described. The polyester that is the raw material for the polyester cord intended in the present invention has an intrinsic viscosity of 0.80 or more, preferably 0.80 to 1.20, as measured at 30°C in a solvent of p-chlorophenol/tetrachloroethane = 3/1 (weight ratio). 85 mol% or more of the structural units, preferably 95 mol% or more, consists of ethylene terephthalate, and other structural units that can be mixed in small amounts include diethylene glycol, other polyethylene glycols having 1 to 10 carbon atoms, hexahydro -p-xylylene glycol, isophthalic acid, dibenzoic acid, p-
Examples include aromatic dicarboxylic acids such as tert-phenyl-4,4'-dicarboxylic acid and hexahydroterephthalic acid, aliphatic dicarboxylic acids such as adipic acid, and hydroxy acids such as hydroxyacetic acid. It is made into fibers by the melt spinning method. Such polyesters can be blended with matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, antistatic agents, dyeability improvers, adhesion improvers, etc. as necessary. All of them can be used, except those that have a serious adverse effect on the characteristics of the present invention depending on how they are blended. Usually, the polyester dried to a moisture content of 0.03% or less is spun using a melt spinning machine, and preferably an extruder type spinning machine is used at this time. The spinning take-off speed is such that the single fiber denier of the collected yarn is 30 denier or less and the birefringence is 0.002 to 0.010.
It is set so that The spinning conditions corresponding to the yarn quality can be determined by optimizing not only the take-up speed but also a number of factors such as the nozzle hole diameter, the distance between the nozzle and the quench, the intrinsic viscosity of the polymer, and the spinning temperature. In particular, it is preferable that the basic spinning factor parameters satisfy the following formula in order to realize the fibers used in the present invention, which have a high degree of polymerization and a small single filament denier. (g) Q/πD ³ ≧23500 [g/cm ³・min] (ch) Vw/Vo≦200 (li) L _H : 30 to 200 [mm] (nu) T _A : 280 to 330 [℃] However, , (G) to (N), Q: Polymer discharge amount per single hole [g/min] D: Nozzle hole diameter [cm] Vw: Spinning take-off speed [m/min] Vo: Nozzle discharge linear velocity [m] /min] L _H : Heating zone length directly below the nozzle [mm] T _A : Indicates the yarn atmosphere temperature in the heating zone directly below the nozzle [°C]. If the birefringence index of the drawn yarn exceeds 0.010, it will not be possible to stably produce a high-strength yarn with a breaking strength DT of 9.5 g/d or more, preferably 11.0 g/d or more. When the degree of polymerization of the polymer is constant, it is preferable that the birefringence of the drawn yarn is as small as possible in order to obtain a high-strength yarn.
If it is less than 0.002, the spinning operation will be impaired, which is not preferable. Furthermore, if the single yarn denier of the drawn yarn exceeds 30 denier, it is difficult to draw it stably at a high draw ratio, and the high strength yarn obtained by drawing at a high draw ratio as intended in the present invention. It becomes difficult to use. When the undrawn yarn obtained as described above is stretched continuously after spinning or once wound, the undrawn yarn first supply roller and the undrawn yarn second supply maintained at 100°C or less are used. Between Laura and
It is best to carry out preliminary stretching of 1.10 times or less, and then perform first-stage stretching of 40% or more of the total stretching ratio between the undrawn yarn second supply roller and the first drawing roller, and if necessary, undrawn yarn. A high-temperature pressurized steam jet nozzle is provided between the second yarn supply roller and the first drawing roller, and the nozzle temperature is set to 200°C or higher to jet high-temperature steam, and the drawing point is fixed near the high-temperature pressurized steam jet nozzle. . Furthermore, when performing the second stage drawing, a slit heater (a heating device provided with a slit as a thread running path) with an ambient temperature of 170 to 420°C was installed between the first drawing roller and the second drawing roller. The yarn is heated while running through the slit in a non-contact state: Ambient temperature refers to the temperature inside the slit.
The film is allowed to pass for 0.3 seconds or more, and then subjected to the second stretching roller. At that time, a temperature gradient is created in the slit heater to increase the atmospheric temperature at the yarn entrance to 170°C or higher and the exit atmospheric temperature to 420°C.
below, and the yarn is in an atmosphere of 200 to 420℃
It is preferable to allow the thread to pass through so that it can stay there for 0.3 seconds or more. In addition, dimensional stability can be further improved by performing a relaxation treatment of 10% or less at 230 to 165°C after two-stage stretching, either continuously without winding or after winding. It is. The total stretching ratio is set to 5.0 times or more, preferably 6.0 times or more. In order to obtain the high strength, low elongation yarn used in the present invention, it is drawn at a high draw ratio of 85% or more of the maximum draw ratio, preferably 90% or more, and the elongation at break is 5 to 12%. The stretching ratio of each sample is basically determined by the degree of orientation of each drawn yarn. Note that the maximum stretching ratio is the average value of the maximum stretching ratios that can be stretched at n=5. The polyester fiber thus obtained has the following properties. (a) DT≧9.5g/d, preferably DT≧11.0g/d (b) 12%≧DE≧5%, preferably 10%≧DE≧5% Furthermore, mechanical loss tangent Tanδ measured at 110C/S
The peak temperature Tα of the main dispersion appearing in the temperature dispersion of is
A temperature of 160°C or higher indicates that the amorphous chains have been sufficiently elongated, and can be said to reflect the fiber quality of (a) and (b) in terms of microstructure. Furthermore, these characteristics can be manufactured more stably by satisfying the following microstructural parameters. (d) △n≧195×10 ^-3 (e) Long period LP≧170Å by small-angle X-ray diffraction (d) (e) Microscopically, △n represents the average orientation, and This shows that LP, which represents the degree of elongation in the fiber axis direction of the crystalline and amorphous parts, is large. In addition, by setting the single yarn denier of the drawn yarn to 4d or less, the radius of the yarn becomes smaller, the difference in heat history and stress history between the inner and outer layers during the spinning and drawing processes becomes smaller, and the structural difference between the inner and outer layers of the filament becomes smaller. By increasing the potency utilization rate, it becomes easier to develop high potency. One feature of the present invention is that it makes it possible to produce fibers with a high degree of polymerization and a small denier, making it possible to use polyester fibers with high strength, low elongation, and a high degree of polymerization for dip cords. There is a particular thing. The polyester multifilament yarn obtained in the above manner is twisted according to a conventional method,
Use raw code. Furthermore, the raw cord or the blind fabric woven from the raw cord is treated with a dip solution to improve its adhesion to rubber, followed by hot stretching. The inventors of the present invention have carefully studied the process from making these raw cords to dip processing, and have been able to make dip cords with higher strength, lower intermediate elongation, and lower shrinkage rate, which is not the case with conventional polyester dip cords. The inventors have discovered that it is possible to achieve superior performance that cannot be achieved previously, leading to the present invention. That is, in the case of the high strength, low elongation polyester fiber used in the present invention, the twist coefficient (T x √) is usually 2000 to 2200 (for example, 840d/2 twist
47turn/10cm), the strength utilization rate of the raw cord will decrease, but the twist coefficient should be set to 1300-2000, preferably 1400-2000.
When set in the range of 1800, the strength utilization rate is very excellent, and by lowering the hot stretch ratio in the dip process to 0 to 3%, a dip cord with a low shrinkage rate and low intermediate elongation can be obtained. The intermediate elongation is a measure corresponding to the modulus of the cord, and the fact that the intermediate elongation of the dip cord is low indicates that the modulus of the cord is high. The feature of the present invention is that, by elongating the molecular chains more than conventional polyester high-strength yarns at the high-strength yarn manufacturing stage, high-strength, high-modulus, low-elongation yarns are already created, and after twisting, In the dip process, the modulus of the dip cord is increased by hot stretching. In other words, since there is no need to lower the intermediate elongation, the load on the cord during the dip treatment process is reduced, resulting in a high-strength polyester with a low shrinkage rate and low intermediate elongation (high modulus) that was previously unimaginable. The goal is to achieve the deep code. No conventional polyester dip cord has a dip cord breaking strength A of 7.5 g/d or more, preferably 8.0 g/d or more, and an intermediate elongation B and dry heat shrinkage C that satisfy the following formulas. Ta. (See Figure 1) (b) B≦5% (c) C≦5% (d) C≦-B+8.5 These dip cord characteristics are based on twist coefficients of 2000~
In the low twist number region of 1300, more preferably 1800 to 1400, the hot stretch ratio in the dip process is 0 to 3.
This can only be achieved under low stretch conditions of %. Reducing the number of twists has the advantage of increasing the twisting speed and reducing costs, but according to conventional knowledge, it has the disadvantage of decreasing fatigue resistance. However, since the dip cord of the present invention satisfies the formulas (a) to (d), even a low-twist cord has a fatigue resistance higher than that of a cord with a conventional twist count. These properties are evident, for example, in the high residual strength after disk fatigue tests. The rubbery or flexible resin referred to in the present invention is
Polyurethane resin, styrene-butadiene rubber,
Chloroprene rubber, ethylene-propylene rubber,
Diene rubber etc. Flat belts such as conveyor belts used in industrial machinery are driven either by having only one side pressed against a belt drive roller, or by having both sides of the belt pressed by nip rollers.
Depends on the drive system of the machine. Therefore, the resin coating is performed by coating, impregnating, or spraying resin on one or both sides of the belt, depending on the purpose. Alternatively, the resin film may be stacked on the base fabric and bonded by heating and pressing. As a result of the belt of the present invention being constructed as described in the claims, it is stronger than conventional belts, has an appropriate elongation suitable for the application, and has high abrasion resistance. The belt also has chemical resistance. Below, methods for measuring the main parameters used to identify the structure and measure the physical properties of the fibers constituting the present invention will be described. <Method for measuring birefringence (△n)> A Nikon polarizing microscope POH type Leitz Bereck compensator was used, and a spectral light source activation device (Toshiba SLS-8-B type) was used as the light source (Na light source). . A sample cut at an angle of 45° to the fiber axis with a length of 5 to 6 mm is placed on a glass slide with the cut side facing up. Place the sample slide glass on the rotating stage so that the sample is at an angle of 45° to the polarizer.
After adjusting the rotary stage by rotating it and inserting the analyzer to obtain a dark field, set the compensator to 30 and count the number of stripes (n pieces). Turn the compensator clockwise to measure the point at which the sample first becomes dark, which is marked a on the compensator, and turn the compensator counterclockwise to measure the point at which the sample first becomes darkest, measured at compensator scale b. After (read up to 1/10 scale in both cases), turn off the compensator.
30, remove the analyzer, measure the diameter d of the sample, and calculate the birefringence (△
n) (average value of 20 measurements). △n=Γ/d (Γ: letter dation Γ=nλ ₀ +ε) λ ₀ =589.3mμ ε: C/ of Leitz compensator manual
Find from 10000 and i. i=(a-b) (: difference in compensator reading) <Measurement method of intrinsic viscosity> Measurement is performed in a mixed solvent consisting of 75% by weight p-chlorophenol and 25% by weight tetrachloroethane. The polymer is dissolved in the solvent at room temperature and viscosity measurements are made in an Ostwald-Fenske capillary viscometer at 30°C. Intrinsic viscosity is the limit value at which the natural logarithm of the ratio of solution viscosity to solvent viscosity divided by the concentration of the polymer solution in grams of polymer per 100 ml of solution approaches zero concentration. <Method for measuring strength and elongation properties of fibers and cords> Based on the definition of JIS-L1017. Take the sample in a skein shape and store it in a temperature and humidity controlled room at 20℃ and 65%RH for 24 hours.
After standing for a period of time, using a “Tensilon” UTM-4L type tensile tester [manufactured by Toyo Baldwin (KK)],
Measurement was performed with a sample length of 20 cm and a tensile speed of 20 cm/min. however,
The raw cord was conditioned while being wound on a ply-twisted bobbin, and then measurements were taken. <Formula for calculating twist coefficient> Twist coefficient K = Number of twists x (denier) ^1/2 Number of twists: turn/10cm <Method for measuring disk fatigue> Using a normal disk fatigue tester, embed dip cord and vulcanize. The prepared test piece was set and heated at 2500 rpm under a compression ratio of 12.5% and an elongation ratio of 6.3%.
After being subjected to forced fatigue by rotation at a speed of 48 hours,
The dip cord was removed from the rubber and its residual strength was measured. <Method for measuring intermediate elongation> According to the definition of JIS-L1017. Measure the elongation rate under a constant load W (Kg). The elongation measurement conditions are similar to those for strength and elongation properties. The constant load W is defined by the following formula. W=4.5×d ₂ /d ₁ d ₂ : sample denier, d ₁ : reference denier, which is 1000 denier for yarn and 2000 denier for cord. <Specific Gravity> Create a density gradient tube made of n-heptane and carbon tetrachloride, place a sufficiently degassed sample into the density gradient tube whose temperature is controlled to 30℃±0.1℃, and leave it for 5 hours. The sample position in the tube was read on the scale of the density gradient tube, and the value was converted into a specific gravity value from the density gradient tube scale to specific gravity calibration graph using a standard glass float, and measured at n=4. As a general rule, read specific gravity values to four decimal places. <Constant length heating thermal stress peak temperature> Test length 45cm, heating rate 20℃/min, initial load 0.05g/
Under the conditions d, the thermal contraction stress is measured from room temperature to the melting temperature, and the temperature at which the thermal stress is maximum is determined.
[For details, see Textile Research Journal, vol.47, 732
(1977)]. <Single thread denier> Measured according to JIS-L1073 (1977). <Measurement method of dry heat shrinkage rate> Take the sample in a skein shape and leave it in a temperature and humidity controlled room at 20℃ and 65% RH for more than 24 hours.
Length l ₀ measured by applying a load equivalent to g/d
The sample was placed in an oven at 150℃ under no tension for 30 minutes.
After being left for a few minutes, it was taken out of the oven and left in the above-mentioned temperature and humidity room for 4 hours, and the above-mentioned load was again applied and measured, and the length _l1 was calculated using the following formula. Dry heat shrinkage rate: l ₀ −l ₁ /l ₀ ×100 [%] <Measurement method of fiber long period LP by small-angle X-ray diffraction> Measurement of small-angle X-ray scattering pattern can be performed using, for example, an X-ray generator manufactured by Rigaku Corporation. (RU-3H type). For measurement, tube voltage 45KV, tube current 70mA, copper anticathode, CuKα made monochromatic with a nickel filter.
(λx=1.5418Å) is used. Attach the fiber sample to the sample holder so that the single threads are parallel to each other. It is appropriate that the thickness of the sample be approximately 0.5 to 1.0 mm. By injecting X-rays perpendicularly to the fiber axes of these parallelly arranged fibers, the PSPC (Position Sensitive Proportional
Counter) system. An overview of this system can be found, for example, in [Polmer Journal, vol.13,
501 (1981)]. The measurement conditions were as follows: 0.3 mmφ x 0.2 mmφ medium pinhole collimator, sample to probe recording distance: 400 mm, MCA (multichannel analyzer), number of measurement channels: 256, measurement time: 600 seconds. Data processing is performed by subtracting the air scattering intensity from the measured scattering intensity, calculating it by moving average processing, and reading the maximum intensity position.
The fiber long period is calculated from the long period small angle scattering angle 2α according to the following formula. [See Figures 2A and B: In the figures, 1' is the sample, 2' is the PSPC probe, 3' is the position analyzer, 4' is the MCA, and 5' is the display section]. LP=λx/2sinα λx=1.5418Å The moving average processing is calculated according to the following formula. I(S)N= _i=N+K 〓 ^i=NK I(S)i/2K+1 where I(S)N and I(S)i are the measured scattering of channel numbers N and i, respectively. Intensity (intensity minus air scattering intensity), K is the number of adopted points of the moving average (here K = 7), N-K>0, N
+K≦256 <Mechanical temperature dispersion> Using Rheovibron manufactured by Toyo Sokki Co., Ltd., initial thread length 4
cm, heating rate 2℃/min, sine frequency 110 during measurement
Hz, and find the temperature (Tα) at which the loss tangent tan δ = E'/E'' is maximum. Example 1 Using polyethylene terephthalate with the intrinsic viscosity shown in Table 1 as a raw material, it was measured under the conditions shown in the table. Spinning was performed to obtain an undrawn yarn with a birefringence shown in the same table. During spinning, an appropriate amount of spinning oil was applied to the surface of the yarn before taking off the undrawn yarn. The yarn was drawn under the conditions shown in Table 2 to obtain a drawn yarn with the quality shown in Table 3. In Table 3, as Comparative Example 2, the yarn quality of a commercially available high-strength grade polyester fiber for tire cords is shown. and Japanese Unexamined Patent Publication 1983
-136852, a case of a polyester fiber in which the maximum heat shrinkage stress was specified is also listed as Comparative Example 3. Note that the evaluation value and toughness described below are expressed as DT×√DE. Here DT is cutting strength (g/d)
DE is cutting elongation (%).

[Table] Furthermore, the undrawn yarn obtained in Comparative Example 3 was
First stretching is performed at 2.3 times using a heating roller at 100°C, then second stretching is performed at 1.12 times through a heating bath at 325°C, and then tension heat treatment is performed through a heating bath at 300°C to obtain a total stretching ratio. A drawn yarn was obtained with a factor of 2.71.

【table】

【table】

[Table] Next, the drawn yarns of Example 1, Comparative Example 2, and Comparative Example 3 were each combined to obtain a 1000 denier multifilament yarn. The resulting yarns were 49T/10cm and 42T/10cm, respectively.
10cm, and 37T/10cm ply twist and ply twist
Made of 1000d/2ply two-stranded cord. The raw cord thus obtained was immersed in a polyester dip consisting of a resorcinol-formalin latex solution, and then dried with hot air at 120° C. for 3 minutes under a 1.5% stretch. Subsequently, it is introduced into the hot stretch zone,
After 1% and 5% hot stretching in heated air at 240°C, a dip cord was produced by further heat-treating in 1% relaxed state for 45 seconds in heated air at 240°C. The properties of the raw cord and dip cord according to this example were as shown in Table 4. The dip cord obtained in the present invention has significantly improved strength compared to the dip cord obtained in the comparative example, and has low intermediate elongation and low dry heat shrinkage, which is a measure of dimensional stability, and has a low dry heat shrinkage rate in the low twist region. Fatigue resistance is much better than the comparative example.

[Table] Next, the single dip cords obtained in Invention 1 and Comparative Example 1 in Table 4 were used as warp threads, and commercially available 1500 denier high-strength polyester fibers were used as weft threads to form a double twill weave structure. A belt was then impregnated with urethane resin containing silicone resin as a smoothing agent. As shown in Table 5, the physical properties of the product are higher in strength and modulus than conventional products.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a diagram showing the characteristics of the dip cord of the present invention, where the vertical axis shows the dry heat shrinkage rate, the horizontal axis shows the intermediate elongation, and the shaded area is the area showing the characteristics of the dip cord of the present invention. Figure 2A is a schematic diagram showing the arrangement of the sample and film surface in the PSPC system used to measure the fiber long period by small-angle X-ray diffraction in the present invention, and Figure 2B is the small-angle X-ray diffraction pattern of the fiber of the present invention. FIG.

Claims (1)

[Claims] 1. The repeating structural unit of ethylene terephthalate is
Ply-twisted fibers made of polyester with a high degree of polymerization of 85 mol% or more and an intrinsic viscosity IV of 0.80 or more, with a twisting coefficient of 2000 to 1300 and coated with a dipping liquid to improve adhesion to rubber. A polyester dip cord having high strength and high modulus, which also has the following properties (a) to (d), and has significantly improved dimensional stability and fatigue resistance. This belt has excellent strength and is made by coating the base fabric with rubber or flexible resin on one or both sides. (a) Breaking strength of the dip cord A≧7.5g/d (b) Intermediate elongation of the dip cord B≦5% (c) Dry heat shrinkage rate of the dip cord C≦5% (d) C≦−B+8.5 2. Patent claim A belt having excellent strength using a polyester dip cord in which the break strength of the dip cord is 8.0 g/d or more and the intrinsic viscosity of the polyester fiber is 0.80 to 1.20 in the range 1 above. 3 In claim 1 or 2,
A belt with excellent strength using polyester dip cord with a twist coefficient of 1800 to 1400. 4. In claim 1, 2, or 3, the peak temperature Tα of the main dispersion appearing in the temperature dispersion of the mechanical loss tangent at 110C/S of the polyester fiber constituting the dip cord is 160 °C or higher. A belt with excellent strength using polyester dip cord. 5. Claims 1 to 4 in which the rubbery or flexible resin is one or a combination of two or more selected from the group consisting of polyurethane resin, styrene-butadiene rubber, chloroprene rubber, ethylene propylene rubber, and diene rubber. A belt having excellent strength according to any one of the items.