JPS6036210A - Belt - Google Patents

Abstract

PURPOSE:To obtain a belt of highly power, low elongation and excellent resistance to abrasion by coating a base cloth of twisted thread made of polyamide fiber, which has its own relative viscosity above a specific value and satisfies predetermined physical properties, with gummous or flexible resin. CONSTITUTION:A required belt such as a conveyor belt and the like is obtained by coating one side or both sides of a base cloth, woven with twisted thread made of polyamide fiber which has its own relative viscosity above 2.3 measured through use of aqueous solution of 96% concentrated sulfric acid at polymer concentration 10mg/ml and at the temperature 20 deg.C, with gummous or flexible resin. At this time, polyamide fiber which satisfies each of the formulas DELTAnA- DELTAnB<0, index of complex refraction DELTAn>=50X10<-3>, cutting strength (g/d)>=11.0, fiber long period (A) due to small angle X-ray diffraction >=100, specific gravity >=1.140, dry contraction rate(%)<=15 is used. Further, DELTAnA, DELTAnB means an index of complex refraction at positions where the ratio of distance r from the center of the fiber to the radius R of the fiber is 0.9, 0.0 respectively.

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 a base fabric made of filament fabric made of synthetic fibers such as aliphatic polyamide, polyethylene terephthalate, and polyvinyl alcohol, and are coated with abrasion-resistant rubber or flexible resin. However, it is difficult to say that it is sufficient in terms of strength, elongation, chemical resistance, etc. That is, the properties required for flat belts, V-belts, etc. are high strength, low elongation, and chemical resistance. It goes without saying that high strength is required, but 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. Thick denier yarns can be used as warp yarns to produce high-strength belts, but this increases weight and thickness, which is undesirable in terms of transportation and handling.

In order to solve these problems,
In Publication No. 75, a twisted yarn composed of fibers mainly composed of polyparaphenylene terephthalamide and fibers mainly composed of polymetaphenylene isophthalamide is used as the warp,
Belts made of fibers mainly composed of polymetaphenylene isophthalamide have been proposed, but there are problems with abrasion resistance when used for long periods of time, and the belt and -
There is a disadvantage that the belt wears out on the contact surface of the mill drive part, 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, Koasunokun yarn, which is made of a core made of metal fiber and surrounded by wholly aromatic polyamide fibers, is used as the warp, and fully aromatic polyamide fiber is used as the weft. A belt has been proposed in which the wholly aromatic polyamide fiber is made of borino-rough vinylene terephthalamide fiber, but it has the same drawbacks regarding abrasion resistance as those mentioned above. Belts used in industrial fields are used to handle various chemicals,
The most commonly used method is to wet the siberto with chemicals such as acids such as sulfuric acid or alkalis such as caustic soda.
In addition, it has been found that the strength of polyparaphenylene terephthalamide fibers decreases rapidly due to corrosion caused by acids, alkalis, etc., and the abrasion resistance significantly decreases in such cases. 0 Under these current circumstances, the present inventors have conducted extensive research into the structure of a belt that has high strength and appropriate elongation, resists corrosion by acids and alkalis, and has excellent abrasion resistance. As a result, the present invention was achieved.

The present inventors conducted various studies on the physical properties and structure of polyamide, and the following facts were confirmed. In other words, the birefringence distribution within the fiber cross section of polyamide fibers made into fibers by the normal spinning and drawing method is smaller than that of polyethylene terephthalate fibers, etc., but the difference in birefringence between the outermost layer and the innermost layer is greater than that of the outer layer. hD tends to be high, and the cutting strength is only about 10 t/<1 at most. In addition, the birefringence in the fiber cross section of known thermoplastic polymer fibers made into fibers by a similar method generally has a distribution in which it increases from the inner layer to the outer layer. This is a factor that inhibits the elasticity and stretchability.

Therefore, we conducted intensive research on spinning and drawing technology and obtained the following knowledge. That is, in the drawing process, for example, the thread (
If the elongation stress can be concentrated in the center of the entire filament by drawing while locally heating the bottom layer, the drawing deformation pattern will be very mild, and the maximum draw ratio that can be reached will be higher than that of the normal drawing method. can be increased. Moreover, as pointed out with conventional drawn yarns, the phenomenon that ``drawing stress concentrates on the surface layer of the yarn, causing strain defects, and the fiber strength is significantly lower than the theoretical strength by υ'' is suppressed, and the final The intrafiber microstructure is a superstretched structure proposed by C1ark et al. [References: W, N, Taylor+Jr, +E, S, C1a
rk+P.

1ym-Eng, Sci., 8, 518 (1978
)-: ], it becomes possible to obtain polyamide fibers having superior tensile strength and breaking strength compared to conventional high-strength fibers for industrial materials. The present invention was completed as a result of further research based on the above findings.
/mt', the value measured at a temperature of 20°C: the same hereinafter) is 2.3 or more, and the birefringence within the fiber cross section is 6nA-△n, (0...・・・・・・・・・(1) (However, △
nA: Birefringence index of the fiber at the position of r/R=0.9 Δnl: Birefringence index of the fiber at the position of r/R=0.0 R: Radius of the fiber cross section r: From the central axis in the fiber cross section distance) Furthermore, the birefringence △n of the fiber (2 at 30°C, 80° R, H,
The measured value after 4 hours (2 or less) is 50X10-3 or more, the cutting strength is 11 r/d or more, the fiber length period by small-angle X-ray diffraction is 100 Å or more, the specific gravity is 1.140 or more, and the dry heat shrinkage rate is This belt is made of a base fabric using twisted threads made of polyamide fibers of 15% or less, and covered with rubber or flexible resin on one or both sides.

The polyamide fiber used in the present invention has a birefringence distribution within the cross section of the fiber that is reversed compared to ordinary thermoplastic polymer fibers, and the inner layer has a higher birefringence than the outer layer of the fiber. It has a unique birefringence distribution. In addition, the fiber length period is 100 Å or more (preferably 110 Å or more), which is significantly longer than ordinary high-strength polyamide fibers, and the microstructure tends to correspond to a superstretched structure, as well as a birefringence Δn≧50×10− 3. (preferably △
n=55X10-3) and specific gravity ≧1.140, indicating physical properties of sufficient stretching heat treatment. In addition, the cutting strength of the fiber, which is the most important practical performance, DT is 11,976 or more, preferably 12,976 or more, and the dry heat shrinkage rate SHD is 15 coefficients or less, and the cutting strength of conventional high-strength polyamide fiber is at most 10 r/ The high-strength polyamide fiber used in the present invention has a low dry heat shrinkage rate of 0, which is significantly improved compared to the conventional high-strength polyamide fiber. Compared to polyamide fibers, it can be said to have a completely new microstructure. In particular, the relative viscosity of the polymer does not need to be extremely high (2.5 or higher (preferably 3.0 or higher) is sufficient. Of course, a higher relative viscosity of the polymer is preferable, but The most important feature of the polyamide fiber used in the present invention is that it has improved properties.

The above-mentioned unique microstructure is exhibited significantly when a polyamide mainly composed of polycaproamide or polyhexamethylene adipamide is used. Among them, polyamide containing 75% or more of polycaproamide is most suitable. This is because polycaproamide has a lower melting point than other polyamides, and it causes stretching stress to concentrate in the center of the yarn. This is because local heating of the surface layer of the yarn is easy and necessary.

The single fiber denier is preferably 35d or less. However, if the single fiber denier becomes large, it becomes difficult to develop a uniform stretching stress concentration in the inner layer portion of the yarn9, and on the contrary, this becomes a factor that inhibits the stretchability. The initial elastic modulus of common polyamide fibers is at most 40 g/d,
The high strength polyamide fiber of the present invention has an initial elastic modulus of 40
R/d or more (preferably 50976 or more), which is extremely high. Another major feature of the polyamide fibers of the present invention is that the heating stress peak temperature, which is a measure of the drawing thermal history, is 200°C or higher (preferably 210'C or higher).

In particular, when the peak temperature is 200° C., it becomes difficult to express the unique distribution of birefringence within the fiber cross section, which is a feature of the present invention.

Next, to explain more specifically the birefringence distribution within the fiber cross section according to the present invention, △nA-Δnm < 0 (1) Preferably △n^-△n, ≦−1. OX 10-3・・・・・・・
... (1') (where ΔnAlΔn is the same as described above) is selected. (1) , (in one equation,
△n^ is △n1 of the outer layer of the yarn, △n is △n of the inner layer of the yarn.
The polyamide fiber of the present invention has a very unique fiber structure in which Δn is smaller in the outer yarn layer than in the inner layer. The method for manufacturing the polyamide fiber used in the present invention having the following will be briefly described, but the present invention is not limited to the following method. In producing the polyamide fibers used in the present invention, the spinning and drawing process, especially the drawing process, is important. That is, for example, the birefringence i) obtained by melt-spinning polyamide with RV≧2.5 is 002 to 0.03.
When stretching the undrawn yarn of No. 5 continuously after spinning or after winding it once, between the undrawn yarn first supply roller and the undrawn yarn second supply roller maintained at 100 ° C. or less, ．．
The undrawn yarn is pre-stretched by 10 times or less, and then the undrawn yarn is stretched between the second drawing roller and the first drawing roller at a total drawing ratio of 4.
It is preferable to perform the first stage drawing of 0% or more, and if necessary, provide a high temperature pressurized steam jet nozzle between the undrawn yarn second supply roller and the first drawing lawn, and set the nozzle temperature to 200°C or more. High-temperature steam is ejected, and a drawing point is fixed near the high-temperature pressurized steam ejection nozzle. Furthermore, when performing the second stage stretching,
A slit heater with an ambient temperature of 170 to 350°C installed between the first stretching roller and the second stretching roller (a heating device with a slit as a yarn running path, and the yarn is drawn into the slit in a non-contact state). Items that heat up while running:;
Ambient temperature refers to the temperature inside the slit).
After that, it is subjected to Utai 2 stretching process. At that time, a temperature gradient is provided in the slit heater, and the ambient temperature at the yarn inlet is set to 160°C or higher and the outlet atmospheric temperature is 350°C or lower, and the yarn is heated to 0.3 se
It is preferable to let the yarn pass through the yarn so that it can stay at C or more.
It is also possible to further improve the dimensional stability by performing a glue lux treatment of less than 30%.

The polyamide that is the raw material for the fiber intended in the present invention is 20
℃, polymer concentration 10''f in 96% concentrated sulfuric acid solution
/ml! 2.3 or more, preferably 3.0 or more, with a relative viscosity measured by , 4-cyclohexanebismethylamine and a linear aliphatic dicarboxylic acid as a base material.

These polyamides may contain polishing agents, pigments,
Light stabilizers, heat stabilizers, anti-α2 agents, antistatic agents, dyeability improvers, adhesion improvers, etc. can all be blended, and depending on how they are blended, they will have a serious adverse effect on the properties of the present invention. Everything else is available.

The fibers used in the present invention are characterized by high strength, high knot strength, and high toughness. The superiority of the physical properties of fibers is closely related to the fine structure of the fibers, and is achieved by a special fine structure that cannot be realized by conventionally known manufacturing methods.

The base fabric in the present invention may be manufactured by any commonly used method such as plain weave or twill weave, but plain weave is most preferred.

The rubbery or flexible resin referred to in the present invention refers to metals such as polyurethane resin, styrene-butadiene rubber, chloroprene rubber, ethylene-propylene rubber, and diene rubber.

Flat belts such as conveyor belts used in industrial machinery are driven by only one side being pressed against a belt drive roller, and sometimes driven by having both sides of the belt pressed by nip rollers. 0 differs depending on the system
Therefore, resin coating can be carried out by coating, impregnating or spraying resin on one or both sides of the belt, depending on the purpose, or by superimposing a resin film on a base fabric and pressing it under heat and pressure.

The belt of the present invention is constructed as described in the claims, and as a result, it has higher strength than conventional belts and can maintain a moderate degree of 1.1 degrees suitable for the purpose. Furthermore, this belt has both abrasion resistance and chemical resistance.

The following describes the main measurement method using a basimeter used to measure the structure and 611 properties of the fibers constituting the present invention.

<Measurement method of viscosity vs. viscosity> Prepare a sample solution by dissolving the sample in 96.3±0.1% by weight reagent special grade concentrated sulfuric acid so that the polymer concentration is 10 T4/ml, and heat at 20°C. Water at a temperature of 0.05℃
Measure the relative viscosity of the solution using an Ostwald viscometer measuring 6 to 7 seconds. The falling time T, (seconds) of 20 ml of sulfuric acid, which is the same as when preparing the sample solution using the same viscometer and the falling time T, (seconds) of the sample solution 20-
(seconds), the relative viscosity RV t is calculated using the above formula.

RV = T, / T.

<Measurement method of birefringence (△n)> A Nikon polarizing microscope P OII type Rhein Berek convensator was used, and a spectral light source activation device (Toshiba 5LS-3-B type) was used as the light source (Na light source). A sample cut at an angle of 45 degrees to the fiber axis with a length of 5 to 6 inches is placed on a slide glass with the cut side facing up. Place the sample slide glass on the fully rotating stage, adjust the rotating stage so that the sample is at a 45 degree angle to the polarizer, insert the analyzer, set the dark field, and set the compensator to 30°. count the number of stripes (n pieces). Turn the compensator clockwise to measure the compensator scale a1 at the point where the sample first becomes darkest Compensator gold The compensator scale bffi to the point at which the sample first becomes darkest by turning the compensator counterclockwise (read up to 1/10 scale), compensator' (i:3
0, remove the analyzer, measure the diameter d' of the sample, and calculate the birefringence (Δn) using the following formula (average value of 20 measurements).

△n = I” / d (1” = n^. 1ε) person. =589.3mμ e: Description of Leitz's compensator Homare's C/10
000 and i 2 (a-b) (: difference in compensator reading)
Measuring method of mn distribution in the fiber cross section〉 The central refractive index (
Nl, O, N/, O) and outer layer refractive index (Nl.

0.9, N/, 0.9) reveals the unique molecular orientation of the fibers obtained according to the invention and can be correlated with the soaked strength of the fibers obtained according to the invention. The distribution of the average refractive index can be measured by observing the fiber from the side surface by the interference fringe method obtained using a transmission quantitative interference microscope (for example, Interfaco, an interference microscope manufactured by Karl Zeiss Jena, East Germany).

This method can be applied to fibers with a circular cross section. The refractive index of a fiber is characterized by the refractive index (N/) for polarized light vibrating parallel to the fiber axis and the refractive index (Nl) for polarized light vibrating perpendicular to the fiber axis. All measurements described here used a xenon lamp as the light source, under polarized light, and with an interference filter wavelength of 544 mμ.
The refractive index (N/ and N
l).

Hereinafter the measurement of Nl and N/ will be billed as N/.

0, N/, and 0.9 will be explained in detail, but Nl(N
Similarly, for Ul, 0 and Nl, 0.9)
It can be determined. The fibers to be tested are optically flat slide glasses and cup glasses, and the fibers are 0.2 to 1
The fibers are immersed in an inert encapsulant with a refractive index (teeth) that provides a shift of the interference fringes within a range of wavelengths. The refractive index (N, ) of the mounting medium is the value measured at 20°C using an Atsube refractometer using green light (wavelength formula = 544 mμ) as a light source.
- From a mixture of brombufthalin 1.48 to 1.6
A refractive index of 1 with a refractive index of 5 can be adjusted. One fiber is immersed in this mounting medium.The interference fringes are photographed and analyzed by magnification of 1000 to 2000 times. The refractive index of N8
．． The average refractive index between ``-8' of Senshu Jin is N/, S'-El
The optical path difference is L=
It is expressed as λ=(N/−N,)t n . Assuming that the refractive index of the sample is 6N, the refractive indices N1 and N of the filled liquid are as follows: N=<N.

N->N.

The pattern of interference fringes as shown in FIG. Nx)tD.

L・N, -I,N・ (7'-Lt L- Therefore, based on equation (7), from the optical path difference at each position from the center of the fiber to the outer periphery, the average refractive index (N
7) The entire distribution can be found. The thickness t can be calculated by assuming that the obtained fiber has a circular cross section. However, due to variations in manufacturing conditions or accidents after manufacturing, there may be cases where the cross section is not circular.

In order to eliminate such inconveniences, it is appropriate to use a portion to be measured where the interference fringes are symmetrically shifted with the fiber axis as the axis of symmetry. The measurements are performed at intervals of i 0.1 H between O and 0.9R, where the radius of the fiber is n, and the average refractive index at each position can be calculated. Since the distribution of N1 can be determined in the same way, the birefringence distribution is △n (r/R)=N/, r/R−N l + r
/R(8). Δn (r/R) is obtained by averaging measurements made on at least 3 filaments, preferably 5 to 10 filaments.

<Tari method for determining strength and elongation characteristics of fibers> Tensilon manufactured by Toyo Baldwin was used, sample length (gauge length) was 100 mm, and elongation speed was 100%/min.

The cutting strength (r/d) was measured by measuring the S-8 curve of single fiber at a recording speed of 500+++ m/min and an initial load of 1/30 p/d.
, cutting elongation (%), Young's modulus (f/d)'a=calculated.

Young's modulus is the maximum slope near the origin of line S-8III! For the calculation of each characteristic value, measurements for at least 5 filaments, preferably 10 to 20 filaments are averaged.

<Measurement method of fiber knot strength> Using Tensilon manufactured by Toyo Baldwin, sample length 50 m
A sample consisting of a single fiber of the loop was attached to a hook mounted on the Tensilon upper and lower chucks, and the gauge length was 50mm, the elongation speed was -100mm/min, and the recording speed was S-8 at 500+m/min.
The curves were measured and the knot breaking strength (r/d), knot breaking elongation (%) were determined. can get.

Measuring method of fiber long period by small-angle X-ray diffraction The measurement of the small-angle X-ray scattering pattern is carried out using, for example, a Rigaku Denki Co., Ltd. 1.νχ ray generator (Model RTJ-3H). Measure with a beam
'CuKa positive pressure 45KVX tube current 70 mA % copper to black electrode, monochrome with nickel filter
-5418 people). The fiber λf is attached to the sample holder.
i1 Attach all single yarns of the sample so that they are parallel to each other. It is appropriate that the thickness of the sample be approximately 0.5 to 1.0 mm thick. By arranging these in parallel and injecting X-rays perpendicularly to the fiber axis of the ``FC'' visceral fibers,
(Po5ition 5intensive Propo
r-tional Counter) system. Overview of this system - For example, CPolm
er JournaLvol-13, 501 (1981
) ) is introduced in detail.

Measurement conditions (0.3 Ω x 0.2 Ω medium pinhole collimator, distance between sample and glove: 400 mm MCA (multi-channel analyzer) i1111 constant number of channels: 256, measurement duration: 600 seconds Data processing is performed by subtracting the air scattering intensity from the measured scattering intensity by moving average processing, and by reading the maximum intensity position, the long-period small-angle scattering angle 2
From α, calculate the fiber long period d according to the following equation (9) [see Figures 2 (A) and (B). In the two figures, 1 is the sample, 2 is the PSPC probe, 3 is the position analyzer, and 4
5 is a display section, and 6 is a microcomputer].

λx=1.5418 people...The rolling average processing is calculated according to the following formula〇However, in the above formula, I(S)N
and I(S)i are the measured scattering intensities (intensities minus air scattering intensities) of channel numbers N and i, respectively,
K is the moving average number of points adopted (here = 7) N - K) 0
, N+≦256 Apparent crystal size: AC8> Calculated using the 5cherrer formula from the half value of the diffraction intensity of the (200) plane of the equatorial diffraction curve in the wide-angle X-ray diffraction diagram [Details published by Maruzen Co., Ltd. "X-ray Crystallography" (Supervised by Isamu Nita) Volume 1] 0 8 cbarrerO formula is expressed by the following formula. rad), α is the correction angle (6,98X10-”ra
d) θ indicates the diffraction angle (degrees).
, tube current 70 mA % copper anticathode, Ni filter, wavelength 1.5418 A, diffractometer 5G-7 type goniometer manufactured by Rigaku Denki Co., Ltd. 1 Rotorflex RU-3H type X-ray generator was used. Q <Mechanical temperature distribution> Rheovibron k manufactured by Toyo Sokki Co., Ltd. was used, the initial yarn length was 4, the heating rate was 2°C/min, and the sine frequency at the time of measurement was 110H.
Measured under the conditions of z, the temperature at which the loss tangent Tan δ = E / g' is maximum
), r is the loss modulus (d)'ne/c++! ).

[For details, see % Memoirs of Faculty
of EngineeringKyushu Univ
ersitLvol, 23, 41 (1963)] The complex modulus of elasticity E is calculated by the following formula.

However, A: Coefficient due to amplitude factor during Tanδ measurement (see Table 1) D: Dynamic Force Dial value 2 sample length (crn) S: Sample cross-sectional area (,4) 1st table Loss modulus El/ is E ” = l El B i n δ
Calculated from -・-aa.

Single thread denier Measured according to JIS-L1073 (1977).

<Dry heat shrinkage rate> Measured at 160°C according to Jl, 5-L1073 (1977).

<Specific gravity> Create a density gradient tube made of toluene and carbon tetrachloride, and
Place a sufficiently degassed sample into a density gradient tube whose temperature is controlled to 0℃±0.1℃, and after leaving it for 5 hours, measure the sample position in the density gradient tube and the value read on the scale of the density gradient tube. , Convert to a specific gravity value from a density gradient tube scale using a standard glass float to a specific gravity calibration chart. 811 constant when n==4. As a general rule, specific gravity values are read with 4 digits after the decimal point.

<Constant length heating thermal stress peak temperature> Trial j%4.5crns heating rate 20℃/min, initial load 06
Under the conditions of 05y/+a, measure the thermal contraction stress from room temperature to the melting temperature, and find the temperature at which the thermal stress is maximum.
See aLvol, 47, 732 (1977). ] The structure and effects of the present invention will be specifically explained below with reference to Examples. In the examples, "parts" and "%" are used unless otherwise specified! Indicates "parts by weight" and "% by weight".

Examples Using polycaproamide with a relative viscosity shown in Table 2 as a raw material,
Spinning was carried out under the conditions shown in the same table, and the birefringence Δ shown in the same table was
n (measured after 24 hours at 30°C and 80% RH) and a relative viscosity of RV. I let it happen. The obtained undrawn yarn was drawn under the conditions shown in Table 3 to obtain drawn yarn having the quality shown in Table 4. Table 4 also shows the yarn quality of the commercially available polycaproamide fiber for tire cord as Comparative Example 1.

(The following are blank spaces) Table 2 Table 3 Table 4 As is clear from Tables 2 to 4, the fibers obtained by the present invention (Examples 1 to 2) exhibit excellent values in all yarn qualities. .

Next, the drawn yarns of Example 2 and Comparative Example 1 were combined to obtain a multifilament yarn of 850 denier.

The multifilament yarns of nylon fibers thus obtained were woven into a double twill structure using the warp yarns, high-strength Cavoriester yarns, and full weft yarns to create a belt fabric impregnated with urethane resin containing silicone resin as a smoothing agent. Their strength and extensibility were compared.

Table 5 shows the comparison results of the thread usage, density, and physical properties of the obtained products of the base fabrics used.

As shown in Table 5, it can be seen that the strength of the present invention is higher, and the elongation is not significantly lowered.

Table 5

[Brief explanation of drawings]

FIG. 1 (A) is a schematic diagram showing interference fringes seen when observed from the lateral direction using the fiber total interference microscope of the present invention, and FIG. 1 (B)
Figure 2 (A) is a schematic diagram showing the arrangement of the sample and film surface in small-angle X-ray diffraction measurement using the PSPC system, and Figure 2 (B) is a schematic diagram of the small-angle X-ray diffraction pattern of the fiber of the present invention. Model applicant: Toyobo Co., Ltd. procedural amendment (spontaneous) October 23, 1980 L Case description 1982 Patent Application No. 1469°82 Name of the invention Bell F & Person making the amendment Related Patent Applicant Mori, 2-2-8 Dojimahama, Kita-ku, Osaka Kusunoki in the detailed description of the invention in the specification to be amended t8 & Contents of the amendment (1) "Or polyheki ( 2
) "Polyhexamethylene sebamide" on page 12, 1Q, line 11 of the specification cylinder is corrected to "polyhexamethylene sebamide, polytetramethylene adipamide."

Claims (1)

[Claims] 1. Relative viscosity of the fiber itself (using a 96% concentrated sulfuric acid aqueous solution,
Measured at a polymer concentration of 10/g and a temperature of 20°C (the same applies below)
is 2.3 or more and satisfies all of the following formulas (1) to (6) on a base fabric using twisted yarn made of polyamide fibers, coated with rubber or flexible resin on one or both sides. A belt. △nA-△nB(0(1) Birefringence Δn≧50 X 10-8 (2) Cutting strength (
2A)≧11.0 (3) Fiber long period (person) by small-angle x-ray diffraction≧100 (4)
Specific gravity≧1.1, i o (5) Dry heat shrinkage rate (chi)≦1 s (a) (However, in formula (1), △nA and △n represent the fiber cross-sectional circular birefringence shown below. ΔnA: birefringence of the fiber at the position of r/R=0.9ΔnB: birefringence of the fiber at the position of r/R=0.0 R=radius of the fiber cross section r: central axis of the fiber cross section Distance from S) 2. Rubber or flexible resin is polyurethane IMJ
IL styrene-butadiene rubber, chloroprene rubber,
The belt according to claim 1, which is one or a combination of two or more selected from the group consisting of ethylene proprene rubber and diene rubber.