JP2012167711A - Transmission belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission belt that may be thinned, has small reduction in belt tension before and after the travel and superior flexural fatigue resistance, and can be suitably used for vehicles and electric devices.SOLUTION: This transmission belt includes core wires embedded in rubber. The core wire comprises polyester slit yarn which comprises polyester having 90 mole percent or more of main repeating units composed of ethylene terephthalate or ethylene 2,6 naphthalate and which has a cross-sectional surface having a width (W) of 0.1 to 5 mm, a thickness (H) of 0.01 to 0.5 mm, and a width-to-thickness ratio (W/H) of 3 to 20.

Description

  The present invention relates to a power transmission belt, and more particularly to a power transmission belt that can be reduced in thickness, has excellent bending fatigue resistance, and is suitably used for automobiles and electrical equipment.

  In recent years, energy saving and energy substitution, including automobiles and electrical equipment, have attracted a great deal of attention in the face of global environmental destruction and oil resource depletion, and in particular, automobiles and electrical equipment have become more compact and lighter for energy and fuel efficiency. As is well known, is being promoted. In this approach, power transmission belts used for driving engine accessories of automobiles, drive gears of electrical equipment, and the like are required to be thinner and lighter in accordance with reduction in size and weight. For these transmission belts, fiber cords such as polyester and aramid are generally used as belt reinforcing cores. Among them, reinforcing fibers have a good balance of strength, elastic modulus, and fatigue resistance, and are most versatile. Polyethylene terephthalate (PET) fibers with a large number of are used.

  Under such a background, for example, Patent Document 1 (Japanese Patent Laid-Open No. 9-236156), Patent Document 2 (Japanese Patent Laid-Open No. 2000-320616), and Patent Document 3 (Japanese Patent Laid-Open No. 2002-2002) are known as techniques for thinning the belt. No. 227051) and Patent Document 4 (Japanese Patent Laid-Open No. 2005-256916), a polyethylene 2,6-naphthalate (PEN) fiber having a higher elastic modulus than PET, or a mixed twist cord of PET and aramid fiber is used as a transmission belt. A technique used for the core wire is disclosed. As described above, the reinforcement layer is made thin by using PEN having a high elastic modulus, and the bending fatigue resistance is improved by the twisted structure, but for the recent significant downsizing of automobiles and electrical equipment, There was still a shortage, and there was a need for further improvement of the transmission belt that can further reduce the thickness of the transmission belt and improve the bending fatigue resistance.

JP-A-9-236156 JP 2000-320616 A JP 2002-227051 A JP 2005-256916 A

  The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to reduce the thickness of the belt before and after running, to reduce bending belt tension, and to be excellent in bending fatigue resistance. It is in providing the power transmission belt which can be used suitably as.

According to the present invention, in a transmission belt having a core wire embedded in rubber, the core wire is made of polyester composed of ethylene terephthalate or ethylene 2,6-naphthalate in which 90 mol% or more of the main repeating unit is formed, It consists of a polyester slit yarn having a cross section with a width (W) of 0.1 to 5 mm, a thickness (H) of 0.01 to 0.5 mm, and a ratio of width to thickness (W / H) of 3 to 20. A power transmission belt is provided.
The polyester slit yarn preferably has a tensile strength of 190 to 700 MPa, a tensile elongation of 10 to 80%, and a 150 ° C. dry heat shrinkage of 0.1 to 8%.

  The transmission belt of the present invention uses a slit yarn having a specific shape, so that the diameter (thickness) of the core wire in the direction perpendicular to the belt thickness is very small compared to a known fiber core wire, Since the elongation-compression ratio that the core wire receives against repeated bending can be reduced, the belt can be significantly reduced in thickness, and the belt tension before and after running is reduced little and excellent bending fatigue resistance. Can be demonstrated.

It is a section perspective view of the V belt concerning the present invention. It is a schematic diagram which shows the measuring method of a belt tension maintenance factor in this invention.

  The transmission belt of the present invention is a transmission belt having a core wire embedded in rubber, and FIG. 1 shows a cross-sectional view of a V-ribbed belt as an embodiment of the transmission belt. A V-ribbed belt 1 shown in FIG. 1 includes an extended portion made of a cover canvas 2, a cushion rubber layer 4 in which a core wire 3 is embedded, and a compression portion, which is an elastic layer, on the lower side. The compression portion has a plurality of trapezoidal ribs 5 having a substantially triangular cross section extending in the belt longitudinal direction.

  The cover canvas 2 is usually a fabric woven into plain weave, twill weave, satin weave, etc., using yarns made of cotton, polyamide, polyethylene terephthalate, aramid fiber, etc., and is integrally bonded to the cushion rubber layer 4. . The rubber layer 4 and the rib 5 formed integrally therewith are not particularly limited, but preferably, for example, an unsaturated carboxylic acid metal salt is added to hydrogenated nitrile rubber or hydrogenated nitrile rubber. Chloroprene rubber, natural rubber, CSM, ACSM, SBR, ethylene-α-olefin-diene rubber. The rubber forming these ribs may be reinforced with short fibers made of aramid, nylon, polyvinyl alcohol, etc., other stabilizers, antioxidants, crosslinking agents, vulcanization accelerators, carbon, silica, etc. Needless to say, these particle components may be added as appropriate.

  In the present invention, a polyester slit yarn (sometimes simply referred to as a slit yarn) is used for the core wire 3 of the transmission belt. The polyester slit yarn is formed by filamentizing a polyester film into a specific width. Is.

  The polyester constituting the polyester slit yarn is a polyester composed of ethylene terephthalate or ethylene 2,6-naphthalate in which 90 mol% or more, preferably 95 mol% or more of the main repeating unit is composed of less than 10 mol%, preferably May contain other copolymerization components in a proportion of less than 5 mol%. Examples of such copolymer components include isophthalic acid, naphthalene dicarboxylic acid, adipic acid, oxybenzoic acid, diethylene glycol, propylene glycol, trimellitic acid, pentaerythritol and the like. These polyesters may contain additives such as stabilizers and colorants. Further, the polymer properties such as terminal carboxyl group concentration and molecular weight are not limited in any way.

  The thickness (H) in the cross section of the polyester slit yarn is 0.01 to 0.5 mm. When the thickness is less than 0.01 mm, the strength that can be practically used cannot be obtained. On the other hand, when the thickness exceeds 0.5 mm, the belt becomes very hard to bend. The belt tension before and after running tends to increase significantly. The thickness is more preferably 0.05 to 0.3 mm.

  Moreover, the width (W) in the cross section of the said polyester slit yarn is 0.1-5 mm. If it is this range, since it can fully apply to the dip processing process of the processing cord of the existing polyester fiber, it is desirable from an industrial viewpoint. If the width is less than 0.1 mm, the strength that can be practically used cannot be obtained. On the other hand, if the width is 5 mm or more, there is a problem that defects such as hip folding in the dip treatment process are likely to occur. The width of the polyester slit yarn is more preferably 0.5 to 3 mm.

  Furthermore, in the cross section of the polyester slit yarn, the ratio (W / H) of the width (W) to the thickness (H) is 2 to 30. When the ratio (W / H) of the width (W) to the thickness (H) of the cross-section of the polyester slit yarn is less than 2, the bending fatigue resistance decreases because the elongation compression strain with respect to bending increases, and before and after running. On the other hand, if the belt tension exceeds 30, the polyester slit yarn breaks against the strain input from the vertical direction, and the durability may be significantly lowered. As for this polyester slit yarn, it is more preferable that the ratio of the width | variety with respect to thickness is 5-20.

  The adjustment of the thickness and width of the polyester slit yarn can be adjusted by the thickness of the polyester film or the slit width when cutting with the slit, and can also be adjusted to the desired size by stretching in the dipping process described later. .

  Further, the tensile strength of the polyester slit yarn is preferably 190 to 700 MPa, and more preferably 240 to 600 MPa. When the tensile strength is less than 190 MPa, the belt strength that can be practically used tends to be difficult to obtain. On the other hand, when the tensile strength exceeds 700 MPa, the polyester slit yarn tends to be easily cut during production and the production tends to be difficult.

  Furthermore, the tensile elongation of the polyester slit yarn is preferably 10 to 80%, and more preferably 15 to 70%. When the tensile elongation exceeds 80%, the transmission belt is deformed too much when subjected to a stress load, so that the practicality of the transmission belt tends to be low. On the other hand, when the tensile elongation is less than 10%, the transmission belt is difficult to extend. Therefore, the flexibility of the belt is inferior, and the bending fatigue resistance may be reduced.

  Moreover, it is preferable that the 150 degreeC dry heat shrinkage rate of the polyester slit yarn used by this invention is 0.1 to 8%, and it is further more preferable that it is 0.5 to 7%. If the dry heat shrinkage at 150 ° C. is less than 0.1%, the heat shrinkage stress necessary to maintain the belt tension is insufficient, which may reduce the transmission efficiency. On the other hand, if it exceeds 8%, the belt dimensions The stability tends to decrease.

  The elastic modulus of the polyester slit yarn is preferably 1 to 30 GPa, more preferably 3 to 20 GPa. If the elastic modulus is less than 1 GPa, the belt may be stretched when the belt is heavily loaded. On the other hand, if it exceeds 30 GPa, the bending fatigue resistance tends to decrease because it is too hard.

  The core dipping process comprising the polyester slit yarn described above is performed by first applying a treatment liquid selected from an epoxy compound and an isocyanate compound to an untreated cord (core wire) and then setting the temperature in a furnace set to 100 to 250 ° C. Pass through ~ 600 seconds to dry and heat stretch set, then apply adhesive solution consisting of RFL liquid, pass through oven set at 150 to 250 ° C for 30 to 600 seconds, set to dry and hot stretch to make treated cord . In the meantime, it is preferable that the total stretching ratio is 0 to 2 times, and the stretching is performed in two or more stages from the viewpoint of increasing the strength and the elastic modulus. Such heat stretching may be performed by slitting the film obtained after biaxial stretching in which the film is manufactured at a high magnification in the vertical direction, and after the film is slit, the known polyester dip treatment is performed. You may carry out at the time of 1 bath and 2 bath dip processing at a process. Stretching can be performed by changing the roller speed before and after the heat treatment furnace at the same time as the above heat treatment, and by increasing the stretching ratio, the strength and elastic modulus are increased, the elongation is decreased, and the fineness, width, and thickness are decreased. It is possible to arbitrarily adjust the shape and physical properties of the polyester slit yarn.

  The polyester slit yarn is provided with an adhesive for bonding the rubber constituting the belt and the polyester. Examples of the adhesive to be applied include an adhesive including an epoxy compound, an isocyanate compound, a halogenated phenol compound, and a resorcin polysulfide compound. Specifically, as the first treatment liquid, an epoxy compound and a block isocyanate are used. A method of applying a latex mixture, applying a liquid (RFL liquid) composed of an initial condensate of resorcin and formaldehyde and a rubber latex (RFL liquid) as the second treatment liquid after the above heat treatment, and further heat-treating is preferable. The latex used here is chloroprene, styrene / butadiene / vinylpyridine terpolymer, hydrogenated nitrile, NBR, CSM or the like. As a method for applying the adhesive, a known dipping process can be used, but means such as contact with a roller, coating with a doctor knife, application by spraying from a nozzle, or immersion in a solution can be employed. Moreover, 0.1 to 10 weight% is preferable and, as for the solid content adhesion amount with respect to this slit yarn, 1.0 to 5.0 weight% is more preferable. In order to control the solid content adhesion amount to the slit yarn, it can be carried out by means such as squeezing with a pressure roller, scraping with a scraper, blowing off with air blowing, suction, etc. In order to do so, it may be attached multiple times.

  An example of the manufacturing method of the V-ribbed belt is as follows. First, after winding the cover canvas 2 and the adhesive rubber layer 4 around the circumferential surface of the cylindrical molding drum, the core wire 3 made of the polyester slit yarn of the present invention is spirally wound thereon, Further, a compressed rubber layer is sequentially wound to obtain a laminate, which is then vulcanized to obtain a vulcanized sleeve. Next, the vulcanization sleeve is hung on a driving roll and a driven roll and travels under a predetermined tension. Further, the rotated grinding wheel is moved so as to abut on the traveling vulcanization sleeve to compress the vulcanization sleeve. A plurality of groove portions of 3 to 100 are polished on the surface of the rubber layer at a time. The vulcanization sleeve thus obtained is removed from the drive roll and driven roll, the vulcanization sleeve is run on other drive rolls and driven rolls, and is cut into a predetermined width by a cutter. A V-ribbed belt 1 can be obtained.

  Hereinafter, the present invention will be described with reference to examples. However, the examples are for illustrative purposes and the present invention is not limited thereto. In addition, evaluation in the Example of this invention was performed with the following measuring method.

(1) Tensile strength, tensile elongation, initial elastic modulus, 150 ° C. dry heat shrinkage Measured according to JIS L1017 and determined.
(2) V-belt tension maintenance rate As shown in FIG. 2, a V-belt is installed between pulleys 6 and 7 having a diameter of 100 mm, the initial mounting tension is 900 N, and the pulley rotation speed during running is 3600 rpm A running test was conducted at room temperature. Then, after stopping running for 4 hours and then allowing to cool for another 24 hours, the tension was measured, and the tension maintenance ratio relative to the initial mounting tension (900 N) was calculated.
(3) Flexural fatigue resistance of V-belt Take out the core wire from the belt after the V-belt running test of (2) above, measure its strength, and the strength against the strength of the core wire taken out from the belt before the belt running test The maintenance rate was calculated.
(4) V-belt weight ratio The belt weight after preparation was indexed with a comparative example as 100, and the belt weight was comparatively evaluated.

[Example 1]
A slit yarn obtained by cutting a 0.13 mm thick polyethylene 2,6-naphthalate (PEN) film (Teonex film manufactured by Teijin DuPont Films Ltd.) into a width of 2 mm is used as a computer treater processor (CA Ritzler Corporation). After dipping in an aqueous dispersion primer composed of epoxy and blocked isocyanate at a speed of 11 m / min using a company-made dip processing machine, it was stretched by 1% at 200 ° C. for 2 minutes, and then 240 ° C. for 1 minute. Followed by 20% elongation at 1 ° C., followed by immersion in a resorcin-formalin-latex (RFL) aqueous dispersion followed by 1% elongation at 170 ° C. for 2 minutes, followed by 70% elongation at 240 ° C. for 1 minute, Winding at a speed of 23 m / min, tensile strength 270 MPa, tensile elongation 18%, elastic modulus 10 GPa, 150 ° C. dry heat shrinkage 3.5%, to obtain a thickness 0.15 mm, a polyester slit yarn process code width 1.0 mm. A V-belt 1 shown in FIG. 1 was prepared by the above-described method using the obtained processing cord as a core wire. Table 1 summarizes the results of the belt tension maintenance factor, bending fatigue resistance, and belt weight ratio of the obtained V-belt.

[Example 2]
A slit yarn obtained by cutting a 0.10 mm thick polyethylene terephthalate (PET) film (Tetron film made by Teijin DuPont Films Ltd.) into a width of 2 mm is used, and this is processed by a computer processor (CA Ritzler, dip treatment). Machine) at a speed of 12 m / min, and then immersed in an aqueous dispersion primer composed of epoxy and blocked isocyanate, stretched 1% at 130 ° C for 2 minutes, and then stretched 20% at 240 ° C for 1 minute. Followed by immersion in a resorcin-formalin-latex (RFL) aqueous dispersion followed by 1% stretching at 170 ° C. for 2 minutes, followed by 60% stretching at 240 ° C. for 1 minute at a speed of 23 m / min , Tensile strength 340 MPa, tensile elongation 25%, elastic modulus 5 GPa, 150 ° C. dry heat shrinkage 5.0%, A polyester slit yarn treatment cord having a thickness of 0.15 mm and a width of 1.1 mm was obtained. A V-belt 1 shown in FIG. 1 was prepared by the above-described method using the obtained processing cord as a core wire. Table 1 summarizes the results of the belt tension maintenance factor, bending fatigue resistance, and belt weight ratio of the obtained V-belt.

[Comparative Example 1]
Two polyethylene 2,6-naphthalate (PEN) fibers having a fineness of 1100 dtex / 249 filament (Teonex fiber, Teijin Fibers Ltd., round cross section) are combined together and twisted at a twist of 200 T / m. The top twisted yarn was twisted at 120 T / m to obtain a twisted cord of 1100 dtex / 2 × 3. Using this twisted cord, after immersing it in a primer of an aqueous dispersion composed of epoxy and blocked isocyanate at a speed of 22 m / min, using a computer treater processor (manufactured by CA Ritzler, dip processor), Dry at a constant length of 130 ° C. for 2 minutes, then 3% elongation at 240 ° C. for 1 minute, followed by immersion in a resorcin-formalin-latex (RFL) aqueous dispersion, 170 ° C. for 2 minutes, then 240 ° C. 1 Each piece was subjected to a constant length heat treatment for a minute and wound up to obtain a polyethylene naphthalate-treated cord. A V-belt 1 shown in FIG. 1 was prepared by the above-described method using the obtained processing cord as a core wire. Table 1 summarizes the results of the belt tension maintenance factor, bending fatigue resistance, and belt weight ratio of the obtained V-belt.

[Comparative Example 2]
Two polyethylene terephthalate (PET) fibers (Tetoron fiber manufactured by Teijin Fibers Ltd., round cross section) with a fineness of 1100 dtex / 249 filaments are combined and twisted at a twist rate of 200 T / m. Twist at a number of 120 T / m to obtain a twisted yarn cord of 1100 dtex / 2 × 3. Using this twisted cord, after immersing it in a primer of an aqueous dispersion composed of epoxy and blocked isocyanate at a speed of 22 m / min, using a computer treater processor (manufactured by CA Ritzler, dip processor), Dry at a constant length of 130 ° C. for 2 minutes, then 3% elongation at 240 ° C. for 1 minute, followed by immersion in a resorcin-formalin-latex (RFL) aqueous dispersion, 170 ° C. for 2 minutes, then 240 ° C. 1 Each piece was subjected to a constant length heat treatment for a minute and wound up to obtain a polyethylene naphthalate-treated cord. A V-belt 1 shown in FIG. 1 was prepared by the above-described method using the obtained processing cord as a core wire. Table 1 summarizes the results of the belt tension maintenance factor, bending fatigue resistance, and belt weight ratio of the obtained V-belt.

  As apparent from Table 1, in the example, by using a thin film-like slit yarn for the core wire, the amount of the core wire and the cushion rubber can be reduced as compared with the comparative example. It can be understood that the bending fatigue resistance and the belt tension maintenance ratio can be remarkably improved because the elongation / compression ratio received by the core wire against bending can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in bending fatigue resistance, making a belt thin, there is little fall of the belt tension before and behind driving | running | working, and it can provide the power transmission belt used suitably for motor vehicles and an electrical equipment. It is very effective in reducing environmental burdens such as downsizing and weight reduction.

1 V-ribbed belt 2 Cover canvas 3 Core wire 4 Cushion rubber layer 5 Ribs 6, 7 Pulley W Width of cross section of polyester slit yarn core wire H Thickness of cross section of polyester slit yarn core wire

Claims (2)

  A transmission belt having a core wire embedded in rubber, wherein the core wire is made of polyester in which 90 mol% or more of main repeating units are composed of ethylene terephthalate or ethylene 2,6-naphthalate, and has a width (W) 0.1 to 5 mm, a thickness (H) of 0.01 to 0.5 mm, and a width-thickness ratio (W / H) of 3 to 20 is a polyester slit yarn having a cross section. Transmission belt. The transmission belt according to claim 1, wherein the polyester slit yarn satisfies the following.
(1) Tensile strength: 190 to 700 MPa
(2) Tensile elongation: 10-80%
(3) 150 ° C. dry heat shrinkage: 0.1 to 8%

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