JP2006057221A - Cord for transmission belt and transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cord for a transmission belt and the transmission belt, especially capable of maintaining a belt tension even after running for a long period as the frictional transmission belt, and reducing noise or vibration on traveling. <P>SOLUTION: This rubber-reinforcing cord used for the transmission belt, consisting of a polybutylene terephthalate fiber, treated with first twists and ply twists of 300-1,500 dtex//1-3 pieces (S- or Z-twisting direction)/2-5 pieces (Z- or S-direction) and having a both twists structure having 600-2,500 twist factor of the first and ply twists is provided by having 0.03-0.20 cN/dtex heat shrinkage stress and 0.2-1.0 cN/dtex stress at 5% stretch. The transmission belt by using the cord is provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transmission belt cord and a transmission belt, and more particularly to a friction transmission belt. More specifically, the present invention relates to a transmission belt that can maintain belt tension even if it is run as a transmission belt for a long period of time and does not cause slippage with a pulley, reduces noise and vibration during running, and has excellent durability, and a cord for the same. Is.

  Transmission belts are used for various purposes such as automobiles, general industries, and agricultural machinery. Transmission belts are broadly divided into friction transmission and synchronous transmission depending on the power transmission mechanism, and the former belongs to V belts, flat belts, etc., and the latter includes toothed belts, just like chains and gears. Used to convey accurate rotation.

  When a power transmission belt is used as a fan belt for an automobile, it is used in the engine room, so heat resistance is required because the ambient temperature is high, and since the belt is arranged in a narrow engine room, the belt Therefore, bending fatigue resistance is also required. Also, the dimensional stability of the belt is extremely important in order to avoid loosening of the belt after running for a long time.

  The power transmission belt requires a certain tension according to the driving conditions during traveling. If the belt tension decreases during running, the gripping force with the pulley decreases and slipping occurs, and power cannot be transmitted sufficiently. The decrease in belt tension is due to stress relaxation of the core cord, due to elongation of the core cord caused by repeated bending and expansion / compression, and when the both sides wear like a V-belt and fall into the groove, the belt stretches upward. It is caused by things such as.

  As described above, there has been a demand for a transmission belt that can prevent a decrease in tension during traveling of the transmission belt, prevent slipping with a pulley, reduce belt wear, and reduce noise and vibration.

  In order to solve the above problems, a transmission belt improvement technique has been proposed and disclosed. For example, there are Patent Document 1, Patent Document 2, and Patent Document 3.

 Patent Document 1 relates to an automatic tension transmission belt in which the belt contracts due to frictional heat generated when the belt slips on the pulley while the belt is running, and the tension necessary for transmission is automatically obtained by tension. Is. That is, the belt tension is maintained by slipping during running, generation of frictional heat by the slip, and thermal contraction of the belt caused by the frictional heat.

  Patent Document 2 states that “a transmission belt in which a polyester cord is used as a tensile body and disposed in a rubber layer and vulcanized and integrated, has a low dry heat shrinkage rate, maintains a high belt tension, and transmits power. Is a power transmission belt having high characteristics and small dimensional change ”, and this problem is that“ the polyester cord taken out from the belt has a specific property, that is, an initial tensile resistance value of 58 g / d ”. As described above, it is described that it can be achieved by “having a characteristic of a thermal stress of 0.5 g / d or more and a stress ratio of 0.928 or more when heated at 150 ° C. for 8 minutes”. That is, Patent Document 2 is characterized by using a stretched heat-set cord that is balanced in thermal stress and stress relaxation while taking advantage of the original yarn characteristics of high-strength polyester fiber. The parameters specify that the initial tensile resistance value is high, the thermal stress is high, and the stress relaxation after repeated load / elongation is small.

Patent Document 3 states that “a high-strength polymer having high tensile strength, excellent energy absorption capability, and excellent dimensional stability, and can be preferably used in industrial material applications such as seat belts, ropes, and rubber reinforcing fibers. Butylene terephthalate fiber ”is a multifilament fiber composed of a polybutylene terephthalate polymer having a high degree of polymerization of 95 to 100 mol% of butylene terephthalate units, and has a tensile strength of 5.8 to 7 0.1 g / d, and the elongation at break is 18.0 to 35.0%. However, Patent Document 3 not only specifically describes the transmission belt, but also the characteristics of polybutylene terephthalate fibers and polybutylene terephthalate fiber cords required as a transmission belt, and means for achieving the characteristics, etc. It is not described at all. In particular, the yarn is designed only to make use of the energy absorbing ability required for the seat belt.
Japanese Patent Publication No. 55-50578 JP-A-62-255637 JP 2003-73920 A

  However, the transmission belt of Patent Document 1 is insufficient to stably tighten the pulley for a long time and maintain the tension, and Patent Document 2 has a high initial tensile resistance value and a high thermal stress. Insufficient to maintain the belt tension over time. The object of the present invention is to solve the above-mentioned problems in the prior art, and to maintain belt tension even when the belt is run for a long time as a transmission belt cord and transmission belt, particularly as a friction transmission belt, reducing noise and vibration during running. Is to provide an improved transmission belt.

  In order to achieve the above object, the transmission belt cord of the present invention is a rubber reinforcing cord having a multi-twisted structure made of polybutylene terephthalate fibers, in which a plurality of lower twisted cords are combined and subjected to upper twisting. The heat shrinkage stress is 0.03 to 0.20 cN / dtex, and the 5% elongation stress is 0.2 to 1.0 cN / dtex. Further, in the transmission belt cord of the present invention, the twisted structure comprises 2 to 5 cords obtained by imparting a twist in the S or Z direction to 1 to 3 cords having a fineness of 300 to 1500 dtex. A preferred embodiment is a structure in which the yarns are twisted and a twist in the reverse Z or S direction is applied, the total fineness is 3000 to 20000 dtex, and the strength is 3.7 to 6.7 cN / dtex. . The transmission belt of the present invention is characterized in that the above-described transmission belt cord is used as a core of the belt.

The transmission belt using the transmission belt cord of the present invention can maintain the initial belt tension even when the belt is run for a long period of time, and is less likely to slip with the pulley, thus reducing noise and vibration during running.

  Below, the preferable aspect of this invention is demonstrated.

  The power transmission belt of the present invention is a rubber reinforcing cord having a multi-twisted structure in which a plurality of lower twisted cords made of polybutylene terephthalate fibers are combined and subjected to an upper twist. Preferably, 2 to 5 cords obtained by applying S or Z direction twist to 1 to 3 cords having a fineness of 300 to 1500 dtex are combined to twist Z or S direction in the reverse direction. In other words, 300 to 1500 dtex // 1 to 3 (S or Z twist direction) / 2 to 5 (Z or S direction) under twist and over twist are applied, under twist and over twist Has a twisted structure having a twist coefficient of 600 to 2500. That is, 1 to 3 polybutylene terephthalate fiber yarns of 300 to 1500 dtex are aligned and subjected to a lower twist in the S or Z twist direction, and then 2 to 5 lower twisted cords thus obtained are opposite to the lower twist. An upper twist is applied in the twist direction to form a twisted structure.

The lower twist and the upper twist coefficient are generally 600 to 2500, preferably 700 to 1500, and the raw cord is formed. The twist coefficient of the cord is the number of twists per 10 cm of each cord of the lower twist when T is a yarn of a plurality of filaments and the upper twist when a plurality of yarns of the yarn is a cord, and D is the cord When the number of display decitex is used, it is expressed by T × D ^1/2 .

  When the twist coefficient is less than 600, the bending fatigue resistance of the belt is poor, and when it exceeds 2500, the load elongation tends to be high, and therefore, the belt tends to be unsuitable for use as a belt core.

  As described above, since the twist structure and twist coefficient of the raw cord affect the modulus and elongation of the cord characteristics, and thus greatly affect the transmission belt characteristics, the cord characteristics are well balanced in the above 600 to 2500 range. It is important to choose where.

  The transmission belt cord is obtained by subjecting the raw cord thus obtained to the following processing.

  An adhesive mainly composed of an epoxy compound or a polyisocyanate compound is applied to the obtained raw cord in the first bath, and then an adhesive mainly composed of resorcin / formalin / latex is applied in the second bath. Drying is performed at 100 to 200 ° C. for 30 to 180 seconds, and heat treatment is performed at 180 to 240 ° C. for 60 to 300 seconds. The adhesive is applied in an amount of 1.0 to 7.0% by weight, usually 2.0 to 5.0% by weight, based on the cord weight. The heat treatment is performed by applying a stretch of 0.5 to 10%, usually 1.0 to 8.0%. Further, the adhesive treatment is usually performed by arranging a plurality of cords.

  By using the polybutylene terephthalate fiber according to the present invention and performing the above twisted yarn, adhesive application and heat treatment, a transmission belt cord for the transmission belt of the present invention is obtained.

  The transmission belt cord according to the present invention is a transmission belt cord made of polybutylene terephthalate fiber having a heat shrinkage stress of 0.03 to 0.20 cN / dtex.

  The heat shrinkage stress of the cord for the transmission belt of the present invention is 0.03 to 0.20 cN / dtex, preferably 0.05 to 0.18 cN / dtex. When the thermal shrinkage stress exceeds 0.20 cN / dtex, the dimensional change becomes remarkably large. Therefore, when the vehicle is run for a long time, the belt is loosened, causing problems such as noise and vibration, and reduced transmission efficiency. On the other hand, when the heat shrinkage stress is less than 0.03 cN / dtex, there is a problem that the tension between the traveling belt and the pulley is too low and the transmission efficiency is lowered.

  The 5% elongation stress of the polybutylene terephthalate fiber cord according to the present invention is 0.2 to 1.0 cN / dtex, preferably 0.4 to 0.8 cN / dtex. When the stress at 5% elongation exceeds 1.0 cN / dtex, slippage occurs in the belt and pulley during long-term running, causing noise and vibration. Moreover, when it is less than 0.2 cN / dtex, the transmission belt and the pulley are loosened, causing problems such as a reduction in transmission efficiency.

  The strength of the transmission belt cord according to the present invention is preferably 3.7 to 6.7 cN / dtex, more preferably 4.0 to 6.7 cN / dtex. The strength may exceed 6.7 cN / dtex, but this is currently technically difficult to achieve. However, if it is less than 3.7 cN / dtex, when used as a power transmission belt cord, the mechanical properties such as tensile properties and bending properties are inferior, which is not appropriate.

  The fiber used for the transmission belt of the present invention is a polybutylene terephthalate composed of a terephthalic acid component and a butylene glycol component, but usually a polyester in which 10 mol% or less is replaced with another dicarboxylic acid component, and / or a diol component as well. It may be a polyester fiber made of polyester partially replaced. Moreover, the polyester fiber which blended the other polyester polymer may be sufficient normally in the range of 10 weight% or less.

  The most suitable fiber for the transmission belt cord of the present invention is polybutylene terephthalate fiber containing polybutylene terephthalate fiber and the above partially copolymerized component, or blended with other polyester polymer.

  The polybutylene terephthalate fiber used in the transmission belt cord of the present invention is a high-strength polybutylene terephthalate polymer because it is used as a transmission belt core body having high strength, excellent repeated bending fatigue, and excellent wear resistance. . The intrinsic viscosity of the polybutylene terephthalate fiber is usually 1.0 to 3.0.

  In addition to the above, the polybutylene terephthalate fiber cord according to the present invention characterized by the above characteristics has the following characteristics.

Transmission belt cord:
Fineness 3000 to 20000 dtex
Strength 3.7-6.7 cN / dtex
Elongation 13-28%
Dry heat shrinkage 5-20%
Initial tensile resistance 130-350 cN / dtex .

  The power transmission belt of the present invention having the above characteristics has a belt and pulley that are in close contact with a power transmission belt using a polyester fiber cord as a core, and the belt hardly loosens because the tension does not decrease even when traveling for a long time. Therefore, there is no slip of the belt and pulley, and noise and vibration are small.

  Next, the fiber used for the transmission belt of the present invention, the transmission belt cord, and the method for manufacturing the transmission belt will be described below.

  First, a method for producing polybutylene terephthalate fibers will be described.

  The above-mentioned polybutylene terephthalate polymer chip is melted by an extruder-type extruder, subsequently filtered in a spin pack, and then spun from a spinneret hole. Here, the spinning temperature is 240 to 280 ° C. The spun yarn passes through the slow cooling region and is then cooled and solidified by blowing cooling air.

  A heating cylinder having a length of 5 to 50 cm, preferably 5 to 8 cm, is attached immediately below the base. The temperature in the heating cylinder is heated to 200 to 350 ° C., and the spun yarn is passed through the atmosphere and gradually cooled. Furthermore, it is preferable to install a heat-insulating cylinder having a length of 10 to 50 cm that does not actively heat the heating cylinder.

  The yarn that has passed through the high-temperature atmosphere in the heating tube and the heat-insulating tube is then cooled and solidified by blowing cold air. The cooling is preferably an annular cooling method in which cooling air is blown from the periphery of the spun yarn. The temperature of the cooling air is 10 to 80 ° C, preferably 15 to 70 ° C.

  Next, the cooled and solidified yarn is then applied with an oil agent, and then wound around a take-up roll that controls the spinning speed. The oil agent to be applied may be a hydrous system or a non-hydrous system. Examples of preferred oil agent compositions include alkyl ether esters as a smoothing agent component, alkylene oxide adduct of higher alcohol as a surfactant component, non-aqueous oil agent diluted with mineral oil as an extreme pressure agent component, and warm water. It is a water-based oil obtained by dilution. The take-up speed (spinning speed) is usually 300 m / min to 1500 m / min, preferably 300 to 1000 m / min. The take-up yarn is usually sent continuously to the drawing process and drawn by a direct spinning drawing process. For the stretching, it is preferable to apply a multi-stage thermal stretching method of two or more stages. The drawing ratio in the two-stage drawing is preferably set so that the first-stage drawing ratio is higher than that in the second stage, thereby preventing the occurrence of yarn swaying, yarn unevenness, and fluff, and obtaining a drawn yarn excellent in quality. be able to. The draw ratio is 3 to 7 times, preferably 4 to 5.5 times. The yarn after hot drawing is continuously heat-set. For heat fixation, a known method such as bringing the yarn into contact with a heat roller or passing through a high-temperature gas is applied. In the case of a heat roller, it is 140-250 degreeC, Preferably it is 150-230 degreeC.

  Furthermore, the heat-set stretched yarn is subjected to a relaxation treatment and then wound up by a winder. The relaxation treatment is performed at 0 to 10%.

Next, a method for manufacturing a transmission belt cord will be described.
The polybutylene terephthalate fiber obtained above was subjected to 300-1500 dtex // 1-3 (S or Z twist direction) / 2 to 5 (Z or S direction) twist and top twist, A twist coefficient of an upper twist is 600 to 2500, twisted in a twisted structure, an adhesive mainly composed of a polyisocyanate compound is applied in the first bath, and then dried at 180 to 200 ° C. for 30 to 180 seconds. Further, an adhesive mainly composed of resorcin / formalin / latex is applied in the second bath, and heat treatment is performed by applying a stretch of 2 to 8% for 60 to 300 seconds in an atmosphere of 180 to 240 ° C. In addition, the stretch here is generally rolled up as it is by applying 2 to 8% stretch in one step, but after applying the stretch of 1.0 to 8.0% once, in a high temperature atmosphere of 180 ° C to 240 ° C By performing a relaxation treatment of 1 to 3%, it is possible to obtain a stable transmission belt cord with small variations in the quality of heat shrinkage stress.

Next, a method for manufacturing the transmission belt will be described.
The example of a manufacturing method of V ribbed belt is shown. A V-ribbed belt 1 shown in FIG. 1 shows an example in which the above-mentioned adhesion-treated transmission belt cord is used as a core wire. According to this, the core wire 2 having the core cord in the adhesive rubber layer 3 is embedded in the adhesive rubber layer 3, and the compressed rubber layer 4 as an elastic body layer is provided on the lower side thereof. The compressed rubber layer 4 is provided with a plurality of ribs 6 having a substantially triangular cross-section extending in the longitudinal direction of the belt, and a rubber canvas 5 attached to the belt surface.

  The power transmission belt of the present invention thus obtained can maintain belt tension even if it is traveled as a power transmission belt for a long period of time and does not slip with the pulley, so that noise and vibration during travel can be reduced.

  The transmission belt of the present invention is applied to, for example, a V-ribbed belt, a wrapped V-belt, a low-edge V-belt, a cogged V-belt, a combined V-belt, a toothed belt, a double-sided V-ribbed belt, a double-sided toothed belt, a toothed V-rib belt and a flat belt. can do. Then, the advantage of the transmission belt of the present invention can be utilized to omit the auto tensioner, or when the conventional auto tensioner is not employed, the belt looseness adjustment work can be reduced.

  Hereinafter, the present invention will be described in detail by way of examples. The definition of each characteristic and the measuring method in the present invention are as follows.

  (1) Thermal contraction stress: Measured according to the method of JISL-1017 (1983). The ambient temperature was 150 ° C., and the standing time was 8 minutes.

  (2) Tensile strength: Measured according to the method of JISL-1017 (1995).

  (3) Stress at 5% elongation, strength, elongation, and initial tensile resistance: measured by the method of JISL-1017 (2002).

  (4) Dry heat shrinkage: measured by the method of JISL-1017 (2002) and 8.10 (Method B).

(5) Intrinsic viscosity (IV): 25 ml of orthochlorophenol was added to 0.125 g of the sample, and the sample solution dissolved by heating at 120 ° C. for 30 minutes was mixed with orthochlorophenol at 25 ° C. using an Ostwald viscometer. The relative viscosity was measured and determined by the following formula.
IV = 0.0242ηr + 0.2634
ηr = (t × d) / (t ₀ × d ₀ )
Where t and t ₀ are the falling seconds of the sample solution and orthochlorophenol, respectively, and d and d ₀ are the densities of the sample solution and orthochlorophenol at 25 ° C., respectively.

  (6) Noise level during running: As shown in FIG. 2, the V-ribbed belt 1 is wound between a driving pulley 7 having a pulley diameter of 140 mm and a driven pulley 8 having a pulley diameter of 70 mm so that the driven pulley 8 is in an unloaded state. The drive pulley 7 is driven at 7000 rpm to run the V-ribbed belt 1, and the sound generated after 10 seconds and 300 hours after the belt running on the belt exit side of the drive pulley 7 is measured by the sound meter 9. The results are shown in Table 1.

[Example 1]
A polybutylene terephthalate chip having IV = 1.95 was supplied to an extruder type extruder and spun by a melt spinning method using a die having 96 holes. At this time, the spinning temperature was 255 ° C., a heating cylinder having a length of 7 cm and a temperature of 300 ° C. was arranged just below the die, and the spinning speed was 400 m / min.

  The drawn yarn was continuously drawn without being wound, and drawn and heat-treated at a final drawing roll temperature of 160 ° C. at a final drawing roll temperature of 5.0 times by two-step drawing at a first to second drawing ratio of 5: 4. Thereafter, relaxation treatment was performed at a relaxation rate of 3.0% to obtain a drawn yarn of 1100 dtex, 96 filaments.

  The obtained fiber had a strength of 6.5 cN / dtex and a heat shrinkage stress value of 0.18 cN / dtex.

The obtained drawn yarn has a 2 × 3 twist configuration (1100 dtex, a configuration in which two 96 filament drawn yarns are aligned and provided with a lower twist, and an upper twist is provided in combination). A twisted cord was obtained by twisting the lower twist and the upper twist with a twist coefficient of 1000 at 21.3 and an upper twist number of 12.3. Subsequently, an isocyanate-based adhesive composed of 95% toluene was added to 5% by weight of a polyisocyanate compound (PAPI-135: manufactured by Sankyo Kasei Dow Co., Ltd.) in the first bath, and then dried at 190 ° C. A second bath was applied with an adhesive consisting of 100 parts by weight of CR latex (chloroprene latex), 14.6 parts by weight of resorcin, 9.2 parts by weight of formalin, 1.5 parts by weight of caustic soda, and 262.5 parts by weight of water. A heat treatment was performed by applying a stretch of 220 ° C. and 4.0% to obtain a cord for a cord.

  The obtained power belt cord had a heat shrinkage stress value of 0.042 cN / dtex, a 5% elongation stress of 0.6 cN / dtex, and a strength of 4.41 cN / dtex.

  Furthermore, after winding one or more cover canvases and an adhesive rubber layer around the peripheral surface of a cylindrical molding drum, a core wire made of a rope is spun spirally on this, and further a compression rubber layer is wound around After obtaining a laminate, this was vulcanized at 140 ° C. for 30 minutes to obtain a vulcanization sleep. Next, the vulcanization sleep is hung on the drive roll and the driven roll and travels under a predetermined tension, and the rotated grinding wheel is moved so as to abut on the vulcanization sleep during travel to move the vulcanization sleep. A plurality of groove portions of 3 to 100 on the surface of the compressed rubber layer were polished at a time. The vulcanization sleep thus obtained is removed from the drive roll and the driven roll, this vulcanization sleep is hung on the other drive roll and the follower roll, traveled, cut to a predetermined width by a cutter, and a V-ribbed belt. Was made.

[Example 2]
In the same manner as in Example 1, polybutylene terephthalate chips were spun by a usual melt spinning method. In the same manner as in Example 1, a drawn yarn of 1100 dtex, 96 filaments was obtained. The obtained fiber had a strength of 6.5 cN / dtex and a heat shrinkage stress value of 0.18 cN / dtex. The obtained drawn yarn was made into a twisted yarn cord in the same manner as in Example 1, subjected to heat treatment by applying a stretch of 220 ° C. and 6.0%, and then relaxed at a temperature of 220 ° C. and 2%. The processing code. The resulting power belt cord had a heat shrinkage stress value of 0.071 cN / dtex, a 5% elongation stress of 0.6 cN / dtex, and a strength of 4.43 cN / dtex. Further, a V-ribbed belt was produced from the processing cord in the same manner as in Example 1.

[Example 3]
In the same manner as in Example 1, polybutylene terephthalate chips were spun by a usual melt spinning method. As in Example 1, the total draw ratio was 5.0 times and the final draw roll was continuously drawn without winding the spun yarn by two-stage drawing with a draw ratio of the first and second stages of 5: 4. After heat treatment at a temperature of 150 ° C., a relaxation treatment was performed at a relaxation rate of 1.0% to obtain a drawn yarn of 1100 dtex and 96 filaments. The obtained fiber had a strength of 6.7 cN / dtex and a heat shrinkage stress value of 0.23 cN / dtex.

  The obtained drawn yarn was made into a twisted yarn cord in the same manner as in Example 1, and subjected to heat treatment by applying a stretch of 220 ° C. and 6.0% to make a cord for cord treatment. The obtained power belt cord had a heat shrinkage stress value of 0.094 cN / dtex, a 5% elongation stress of 0.6 cN / dtex, and a strength of 4.58 cN / dtex. Further, a V-ribbed belt was produced from the processing cord by the same method as in Example 1.

[Example 4]
In the same manner as in Example 1, polybutylene terephthalate chips were spun by a usual melt spinning method. As in Example 1, the total draw ratio was 5.0 times and the final draw roll was continuously drawn without winding the spun yarn by two-stage drawing with a draw ratio of the first and second stages of 5: 4. After heat treatment at a temperature of 150 ° C., a relaxation treatment was performed at a relaxation rate of 1.0% to obtain a drawn yarn of 1100 dtex and 96 filaments. The obtained fiber had a strength of 6.7 cN / dtex and a heat shrinkage stress value of 0.23 cN / dtex.

  The obtained drawn yarn was made into a twisted yarn cord in the same manner as in Example 1, subjected to heat treatment by applying a stretch of 8.0% at a temperature of 220 ° C., and then relaxed at a temperature of 220 ° C. and 2% for a cord. The processing code. The resulting power belt cord had a heat shrinkage stress value of 0.171 cN / dtex, a 5% elongation stress of 0.6 cN / dtex, and a strength of 4.61 cN / dtex. Further, a V-ribbed belt was produced from the processing cord by the same method as in Example 1.

[Comparative Example 1]
Polyethylene terephthalate chips having IV = 1.95 were supplied to an extruder-type extruder and spun by a melt spinning method using a die having 96 holes. At this time, the spinning temperature was 290 ° C., a heating cylinder having a length of 7 cm and a temperature of 330 ° C. was disposed just below the die, and the spinning speed was 400 m / min.

  The drawn yarn is continuously unwound and drawn at a final draw roll temperature of 210 ° C. at a final draw roll temperature of 5.0 ° C. by two-stage drawing with a draw ratio of the first and second stages of 5: 4. After that, relaxation treatment was performed at a relaxation rate of 3.0% to obtain a drawn yarn of 1100 dtex, 96 filaments. The obtained fiber had a strength of 7.7 cN / dtex and a heat shrinkage stress value of 0.46 cN / dtex.

  The obtained drawn yarn was formed into a twisted yarn cord by the same method as in Example 1, and subjected to heat treatment by applying a stretch of 220% at a temperature of 220 ° C. to obtain a cord for cord processing. The resulting power belt cord had a heat shrinkage stress value of 0.32 cN / dtex, a 5% elongation stress of 3.2 cN / dtex, and a strength of 6.10 cN / dtex. Further, a V-ribbed belt was produced from the processing cord by the same method as in Example 1.

[Comparative Example 2]
In the same manner as in Example 1, polybutylene terephthalate chips were spun by a usual melt spinning method. In the same manner as in Example 1, a drawn yarn of 1100 dtex, 96 filaments was obtained. The obtained fiber had a strength of 6.5 cN / dtex and a heat shrinkage stress value of 0.18 cN / dtex.

  The drawn yarn thus obtained was made into a twisted yarn cord in the same manner as in Example 1, subjected to heat treatment by applying a stretch of 220 ° C. and 6.0%, and then relaxing at a temperature of 220 ° C. and 0.5%. Process code for lines. The obtained power belt cord had a heat shrinkage stress value of 0.014 cN / dtex, a 5% elongation stress of 0.7 cN / dtex, and a strength of 4.26 cN / dtex. Further, a V-ribbed belt was produced by the same processing code as in Example 1.

[Comparative Example 3]
In the same manner as in Example 1, polybutylene terephthalate chips were spun by a usual melt spinning method. As in Example 1, the total draw ratio was 5.0 times and the final draw roll was continuously drawn without winding the spun yarn by two-stage drawing with a draw ratio of the first and second stages of 5: 4. After heat treatment at a temperature of 150 ° C., a relaxation treatment was performed at a relaxation rate of 1.0% to obtain a drawn yarn of 1100 dtex and 96 filaments. The obtained fiber had a strength of 6.7 cN / dtex and a heat shrinkage stress value of 0.23 cN / dtex.

  The obtained drawn yarn was made into the same method twisted yarn cord as in Example 1 and subjected to heat treatment by applying a stretch of 220 ° C. and 0.5% to a cord for cord. The obtained power belt cord had a heat shrinkage stress value of 0.027 cN / dtex, a 5% elongation stress of 0.7 cN / dtex, and a strength of 4.29 cN / dtex. Further, a V-ribbed belt was produced from the processing cord by the same method as in Example 1.

  For the V-ribbed belts of Examples 1 to 4 and Comparative Examples 1 to 3, the noise level during running was evaluated, and the results, fiber properties and cord properties are shown in Table 1.

  As is apparent from Table 1, in the present invention (Examples 1 to 4), the generation of noise during traveling is suppressed to a low level.

It is sectional drawing of the one aspect | mode of the V ribbed belt which concerns on this invention. 1 is a schematic view of a belt noise test apparatus according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V ribbed belt 2 Core wire 3 Adhesive rubber layer 4 Compression rubber layer 5 Rubber canvas 6 Rib 7, 8 Pulley 9 Idler pulley 10 Drive pulley 11 Driven pulley 12 Sound meter

Claims (3)

 A rubber reinforcing cord made of polybutylene terephthalate fiber and having a twisted structure in which a plurality of lower twisted cords are combined and subjected to upper twisting. The heat shrinkage stress is 0.03 to 0.20 cN / dtex, 5 A cord for a transmission belt, wherein the% elongation stress is 0.2 to 1.0 cN / dtex. The twisted structure is composed of 2 to 5 cords obtained by applying a twist in the S or Z direction to 1 to 3 cords having a fineness of 300 to 1500 dtex. The transmission belt cord according to claim 1, wherein the cord has a total twist of 3000 to 20000 dtex and a strength of 3.7 to 6.7 cN / dtex.  A transmission belt comprising the transmission belt cord according to claim 1 or 2 as a core of the belt.

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