JP5355324B2 - Toothed belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a belt by keeping a friction coefficient low for a long period while making adhesiveness to a belt body satisfactory. <P>SOLUTION: The toothed belt 10 includes the belt body 11 which has teeth 15 and bottoms 16 alternately provided on one surface 11A along the longitudinal direction and is formed of rubber. The one surface 11A of the belt body 11 is coated with tooth cloth 17. The tooth cloth 17 is subjected to an impregnation treatment with rubber cement containing high density polyethylene of 15-40 pts.wt. to rubber component of 100 pts.wt.. An average molecular weight of the high density polyethylene is 300,000 to 400,000. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a belt for use in a high load environment, in particular, an internal combustion engine of an automobile, etc., in which a rubber paste impregnated in a tooth cloth is improved.

  In an internal combustion engine such as an automobile, a toothed belt is widely used to transmit power from a crankshaft to a camshaft. Since a high load is generally applied to a toothed belt used in an internal combustion engine, the life of the toothed belt tends to be relatively short. In recent years, internal combustion engines have been reduced in size, and accordingly, toothed belts have been made narrower, so that a higher load is applied to the toothed belts. Further, the internal combustion engine is often operated in a relatively high temperature environment, and it is necessary to improve the durability performance of the toothed belt in the high temperature environment.

  One way to extend the belt life is to reduce the load applied to the belt teeth by reducing the friction coefficient of the tooth surface. Specific methods for lowering the coefficient of friction include, for example, treating the surface of a tooth cloth with polytetrafluoroethylene (PTFE), or having a low coefficient of friction such as ultra high molecular weight polyethylene (UHMWPE) powder having a molecular weight of 1 million or more. Can be added to the tooth cloth treatment liquid (see, for example, Patent Document 1).

JP 2003-12818 A

  However, when the tooth cloth surface is treated with PTFE or UHMWPE powder is added to the tooth cloth treatment liquid, the adhesion between the belt body and the tooth cloth may be lowered. In addition, since these have low compatibility with rubber and are separated from the surface of the tooth cloth as the belt is operated, the friction coefficient of the belt tooth surface may increase over time. Therefore, the belt whose friction coefficient is improved by PTFE or UHMWPE cannot sufficiently improve the life of the belt.

  The present invention has been made in view of the above problems, and while making the adhesion of the tooth cloth to the belt body good, the friction coefficient is made low over a long period of time, and the belt life, particularly in a high temperature environment. An object of the present invention is to provide a toothed belt capable of extending the life.

  A toothed belt according to the present invention includes a belt body formed of rubber, with tooth portions and tooth bottom portions alternately provided on one surface along the longitudinal direction, and a tooth cloth covered on one surface. The tooth cloth is characterized by being impregnated with rubber paste containing 15 to 40 parts by weight of high-density polyethylene with respect to 100 parts by weight of the rubber component.

  The average molecular weight of the high density polyethylene is preferably 300,000 to 400,000. Moreover, it is preferable that rubber paste contains HNBR or NBR. The rubber that forms a part of the belt body and is adhered to the tooth cloth preferably includes high-density polyethylene, and more preferably further includes HNBR. The toothed belt according to the present invention is used in, for example, an internal combustion engine.

  In the present invention, the rubber paste impregnated in the tooth cloth contains a predetermined amount of high-density polyethylene, so that the adhesive strength between the tooth cloth and the tooth rubber layer in a high temperature environment and the friction coefficient of the tooth surface are improved. The durability of the belt in a high temperature environment can be improved. Furthermore, generation | occurrence | production of abnormal noise can be suppressed by reducing the friction coefficient of a tooth surface.

It is a side view of a toothed belt concerning this embodiment. It is sectional drawing which shows the manufacturing method of a toothed belt typically. It is sectional drawing which shows the manufacturing method of a toothed belt typically. It is a perspective view which shows the adhesion test sample used for the adhesive strength test. It is a perspective view which shows the state which attached the adhesion test sample to the tensile tester. It is a graph which shows the result of an adhesive strength test. It is a schematic diagram which shows the layout of the transmission system used by a durability performance test. It is a graph which shows the result of an endurance performance test.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a toothed belt according to an embodiment of the present invention. The toothed belt 10 is an endless belt used in, for example, an internal combustion engine of an automobile, and is, for example, a power transmission belt used for transmitting power from a crankshaft to a camshaft.

  The toothed belt 10 includes a belt main body 11 formed of rubber, and a core element 18 embedded in the belt main body 11 and extending along the longitudinal direction of the belt. For example, a plurality of core elements 18 are arranged in the width direction by spirally winding a pair of core wires along the longitudinal direction of the toothed belt 10. Become. On one surface (tooth surface) 11A of the belt body 11, tooth portions 15 and tooth bottom portions 16 are alternately provided along the longitudinal direction.

  The belt body 11 includes a tooth rubber layer 12 provided on the tooth surface 11 </ b> A side of the belt body 11, a back rubber layer 13 provided on the other surface (back surface) 11 </ b> B side of the belt body 11, and these tooth rubber layers 12. And the core rubber layer 14 provided between the back rubber layer 13 and the back rubber layer 13 are integrally formed. The core element 18 is disposed on the boundary surface between the back rubber layer 13 and the core rubber layer 14, and the boundary surface between the back rubber layer 13 and the core rubber layer 14 substantially matches the pitch surface of the belt 10. That is, in the present embodiment, the belt body 11 on the back side of the core element 18 is formed by the back rubber layer 13, and the belt body 11 on the tooth surface side of the core element 18 has the tooth rubber layer on the core rubber layer 14. 12 are laminated.

  The boundary surface between the core rubber layer 14 and the tooth rubber layer 12 has a shape corresponding to the shape of the tooth surface 11A, and is farthest from the pitch surface (core element 18) at the center of the tooth portion 15 in the belt longitudinal direction. At the same time, the pitch surface (core element 18) approaches as the tooth bottom portion 16 is approached. That is, the core rubber layer 14 swells upward in accordance with the shape of the tooth portion 15 inside the tooth portion 15 and constitutes a central portion inside the tooth portion 15. Further, the tooth rubber layer 12 in the tooth portion 15 is laminated so as to surround the tooth surface 11A side of the core rubber layer 14, and is disposed along the tooth surface 11A. On the other hand, in the vicinity of the tooth bottom portion 16 and the tooth bottom portion 16, both the core rubber layer 14 and the tooth rubber layer 12 are thin layers.

  The core rubber layer 14 has a large number of short fibers 20 mixed in substantially uniformly, and has a higher modulus than the tooth rubber layer 12 and the back rubber layer 13 in which the short fibers 20 are not mixed. As the short fiber 20, an aramid short fiber having a relatively high modulus is preferably used. In the present embodiment, by increasing the modulus of the core rubber layer 14 over the tooth rubber layer 12, the tooth surface portion can be softened while suppressing the rigidity of the entire tooth portion 15 from being lowered. Therefore, it is possible to improve the durability performance of the tooth portion 15 while suppressing cracks on the tooth surface and bottom of the tooth, generation of abnormal noise during belt operation, and the like.

  The modulus of the rubber layer refers to a stress when a test piece obtained by vulcanizing the same rubber composition as the rubber layer is stretched by 20% measured according to JIS K6251. In addition, when the short fiber is mixed in the rubber layer, the modulus measured when the short fiber is oriented in one direction in the test piece and the test piece is pulled in the orientation direction. The test piece was vulcanized rubber collected using JIS K6251 dumbbell No. 5 type.

  In the core rubber layer 14, the short fibers 20 are regularly distributed. Specifically, the short fibers 20 are oriented substantially in the thickness direction of the belt in the central region of the tooth portion 15, and with respect to the thickness direction so as to follow the tooth surface as the tooth surface is approached from the central region. In the vicinity of the top portion of the tooth portion 15 and in the vicinity of the tooth bottom portion 16, it is oriented substantially along the longitudinal direction of the belt.

  On the outer periphery of the tooth rubber layer 12, that is, one surface 11A of the belt main body 11, a tooth cloth 17 is adhered and coated. It is preferable that the tooth cloth 17 in this embodiment contains a polyarylate fiber. For example, the tooth cloth 17 is composed of a warp yarn extending in the width direction of the belt and a woven fabric woven by a weft yarn extending in the longitudinal direction of the belt, and the weft yarn preferably includes polyarylate. For example, the weft yarn is a composite yarn including a yarn made of polyarylate fiber and a yarn made of fiber having higher stretchability than polyarylate fiber (hereinafter referred to as high stretch fiber yarn). For example, the composite yarn is constituted by using a highly stretchable fiber yarn as a core yarn, a polyarylate fiber yarn is wound around the core yarn, and a cover yarn is wound around the polyarylate fiber yarn.

  As the highly stretchable fiber yarn, for example, urethane elastic yarn or the like is used, and as the cover yarn, for example, a yarn composed of nylon fiber, polyester fiber or the like is used. The polyarylate fiber used for the weft is made of a so-called wholly aromatic polyester, and specific examples thereof include Vectran (trade name, manufactured by Kuraray Co., Ltd.). The material of the warp yarn of the tooth cloth 17 is not particularly limited, but is composed of nylon fiber or polyester fiber.

  Before the tooth cloth 17 is bonded to the tooth rubber layer 12, the tooth cloth 17 is dipped in a rubber paste containing a rubber component and high-density polyethylene and then dried to be impregnated with the rubber paste. Thereby, rubber paste is vulcanized at the time of vulcanization molding, and the tooth cloth 17 is easily bonded to the tooth rubber layer 12. As the high-density polyethylene, for example, a particulate or fibrous one may be used, and the surface may be surface-treated by adding an OH group and / or a COOH group to the surface. In the present specification, the high density polyethylene means a specific gravity of 0.92 or more, and the specific gravity is preferably 0.92 to 0.96. The deflection temperature under load (according to ASTM-D648) of the high-density polyethylene added to the rubber paste is, for example, about 100 to 130 ° C., and the average molecular weight by the viscosity method (MFR) is about 300,000 to 400,000. Note that high-density polyethylene does not have a crosslinkable portion with other molecules.

  In this embodiment, the adhesiveness between the tooth cloth 17 and the tooth rubber layer 12 can be improved because the rubber paste contains the high-density polyethylene. Further, since the friction coefficient of the tooth cloth surface (that is, the tooth surface 11A) can be reduced by the high density polyethylene, the effective tension during the belt operation can be reduced and the load applied to the belt can be reduced. . Furthermore, since the high-density polyethylene having the above molecular weight can be sufficiently mixed and compatible with the rubber component of the rubber paste by a method described later, it is prevented from being detached from the tooth cloth with the belt operation.

  The high-density polyethylene is blended in an amount of 15 to 40 parts by weight with respect to 100 parts by weight of the rubber component in the rubber paste. If less than 15 parts by weight of high-density polyethylene is blended, the effect of reducing the friction coefficient of the belt is limited, and the adhesive force of the tooth cloth 17 to the tooth rubber layer 12 cannot be sufficiently increased. On the other hand, when the amount is more than 40 parts by weight, the friction coefficient, particularly the friction coefficient in a high temperature environment increases due to the sticking caused by softening of the high density polyethylene, and the durability of the belt cannot be sufficiently improved. In order to further enhance the durability of the belt in a high temperature environment, the high density polyethylene is preferably blended in an amount of 24 to 40 parts by weight with respect to 100 parts by weight of the rubber component of the rubber paste, and the friction coefficient is sufficiently reduced. And in order to fully raise the adhesive strength of the tooth cloth 17 and the tooth rubber layer 12, it is more preferably 24 to 32 parts by weight.

  Rubber components used in rubber paste include HNBR (hydrogenated nitrile rubber), fluorine rubber, NBR (nitrile rubber), mixtures thereof, or one or more of these rubbers mixed with other types of rubber, etc. Among these rubber components, HNBR or NBR is preferably used. The rubber composition of the rubber paste is obtained by blending various additives such as a vulcanizing agent, an anti-aging agent, a vulcanization aid, and carbon black in addition to a rubber component and high-density polyethylene.

  In the present embodiment, the rubber paste is prepared as follows. First, the additives of the rubber composition other than the vulcanizing agent including high density polyethylene are kneaded with the rubber (primary kneading). At this time, the kneading temperature is equal to or higher than the deflection temperature under load of the high-density polyethylene. Therefore, the high-density polyethylene is mixed with the rubber in a softened state, and is well mixed and compatible with the rubber. A vulcanizing agent is further added to the mixture after the primary kneading, and the mixture is kneaded at a temperature lower than the vulcanizing temperature of the vulcanizing agent (below the kneading temperature of the primary kneading) to obtain a rubber composition (secondary kneading). Then, an organic reinforcing agent such as phenol resin, a solvent and the like are added to the rubber composition to obtain a rubber paste. The above rubber composition can be obtained by mixing the rubber component with the rubber component at a temperature higher than the deflection temperature under load and the vulcanizing agent with the rubber component at a temperature lower than the vulcanization temperature. Kneading is not necessary. For example, additives other than the vulcanizing agent may be added by secondary kneading.

  The tooth rubber layer 12, the back rubber layer 13, and the core rubber layer 14 are formed by vulcanizing a rubber composition. As the rubber component of the rubber layers 12 to 14, the same rubber component as exemplified in the rubber paste is used, but HNBR is preferably used. Moreover, it is preferable that the same kind of rubber is used as the rubber component of the rubber layers 12 to 14. Further, the rubber component of the tooth rubber layer 12 is preferably the same type of rubber as the rubber component of the rubber paste.

  The rubber composition of each of the rubber layers 12 to 14 includes various additives such as a vulcanizing agent, an anti-aging agent, a vulcanization aid, and carbon black in addition to the rubber component. Further, the rubber composition of the rubber layers 12 to 14 contains a metal salt of an α, β-ethylenically unsaturated carboxylic acid such as zinc (meth) acrylate in order to improve these strengths. Is preferred.

  In the present embodiment, the rubber composition of the tooth rubber layer 12 preferably contains high density polyethylene. The high-density polyethylene added to the rubber composition of the tooth rubber layer 12 is the same as the high-density polyethylene compounded in the rubber paste. When the rubber composition of the tooth rubber layer 12 contains high-density polyethylene, the rubber composition of the tooth rubber layer 12 is preferably obtained by kneading by the same method as the rubber composition of the rubber paste.

  When the high-density polyethylene is included in the tooth rubber layer 12, tan δ at 100 to 120 ° C. of the tooth rubber layer 12 measured by the dynamic viscoelasticity measurement method is in the range of 0.100 to 0.120. It is preferable. Note that tan δ is a loss tangent (= E ″ / E ′) that is a ratio of a storage elastic modulus (E ′) corresponding to elasticity and a loss elastic modulus (E ″) corresponding to viscosity. In the present embodiment, since the tan δ of the tooth rubber layer 12 falls within the above range under a high temperature environment, it becomes easy to absorb the load energy that acts on the meshing surface (tooth surface 11A) of the belt under a high temperature environment. Even when used in a high-temperature environment, the generation of abnormal noise that occurs during meshing is prevented. Further, by incorporating the high-density polyethylene having the above properties into the tooth rubber layer 12, the adhesiveness between the tooth rubber layer 12 and the tooth cloth 17 can be enhanced while keeping tan δ within the above range. Can be increased.

  Tan δ is a thickness of 1.9 to 2.7 mm, a width of 6 mm, and a length of 5 mm made from a sample obtained by vulcanizing the same rubber composition as the tooth rubber layer at a temperature of 120 ° C. for 20 minutes. This is measured using a sample. In addition, as a measuring device, a viscoelasticity spectrometer manufactured by Shimadzu Corporation (trade name: viscoelasticity testing machine, Triton 2000 made by Triton) was used, and the measurement was performed under measurement conditions of amplitude ± 2.5% and frequency 1 Hz. To do.

  In the rubber composition of the tooth rubber layer 12, the high-density polyethylene is blended in an amount of 10 parts by weight or less, preferably 3 to 10 parts by weight, particularly preferably 5 to 10 parts by weight based on 100 parts by weight of the matrix rubber. If less than 3 parts by weight of high-density polyethylene is blended, the improvement in durability and sound performance is limited. If more than 10 parts by weight is blended, the durability and sound performance are not substantially improved. Moreover, when 5-10 weight part is mix | blended, durability performance can be improved especially effectively. “100 parts by weight of matrix rubber” means that rubber and α, β-ethylenically unsaturated carboxylic acid are used when a metal salt of α, β-ethylenically unsaturated carboxylic acid is blended in the rubber composition. This indicates that the total amount with the metal salt is 100 parts by weight, and when the metal salt of the α, β-ethylenically unsaturated carboxylic acid is not blended, it indicates that the rubber alone is 100 parts by weight.

  An intermediate canvas 21 is embedded in the back rubber layer 13 at a position away from the core wire element 18 and substantially parallel to the pitch surface (core wire element 18). The intermediate canvas 21 spreads in a planar shape along the longitudinal direction and the width direction of the belt, and is provided throughout the longitudinal direction and the width direction of the belt. The intermediate canvas 21 is a canvas having high rigidity in the belt width direction and stretchable in the belt longitudinal direction. As the intermediate canvas 21, a canvas having an elastic modulus of 100 GPa or more in the belt width direction is preferably used, and a canvas having an elastic modulus of 180 to 240 GPa is particularly preferably used. The elastic modulus is measured based on the initial tensile resistance of JIS L1095 9.13.

  The intermediate canvas 21 is a woven fabric woven by warp yarns 22 extending in the belt width direction and weft yarns 23 extending in the belt longitudinal direction, and is woven, for example, in a twill weave or a plain weave. As the warp yarn 22 of the intermediate canvas 21, a high-rigidity non-stretchable yarn is used. For example, a yarn composed of aramid fiber, polyparaphenylene benzobisoxazole (PBO) fiber, carbon fiber, or a mixed fiber thereof is used. Is done. Further, as the weft thread 23, an elastic thread is used, for example, a crimped nylon thread such as woolly nylon.

  In this embodiment, the intermediate canvas 21 having high rigidity in the belt width direction is embedded in the back rubber layer 13, so that the torsional rigidity of the toothed belt 10 is improved without increasing the rigidity of the tooth portion 15, and the belt operation. The effective tension at the time can be reduced. When the effective tension is reduced, the load acting on the belt is suppressed and the durability of the belt can be improved. Further, by using the stretchable yarn as the yarn extending in the longitudinal direction of the belt of the intermediate canvas 21, the intermediate canvas 21 can be easily attached to the toothed mold in the manufacturing process described later, and the formability of the belt is improved. be able to. In the present embodiment, the intermediate canvas 21 may be omitted.

  Next, the manufacturing process of the toothed belt 10 will be described with reference to FIGS. FIG. 2 shows a toothed mold 31 with a pre-formed rubber tooth cloth 32, a core wire 18 ′, an intermediate canvas 21 ′ having a first back rubber sheet 13A ′ affixed thereto, and a second back rubber sheet 13B ′. The winding process is shown. Note that the tooth rubber sheet 12 ′, the core rubber sheet 14 ′, and the back rubber sheets 13 A ′ and 13 B ′ in FIG. 2 are respectively formed in the belt 10 after the vulcanization molding in the tooth rubber layer 12, the core rubber layer 14, and the back rubber layer 13. It will be. Each of the rubber sheets is obtained by forming an unvulcanized rubber composition into a sheet, and the core rubber sheet 14 'is blended with short fibers 20. Further, the tooth cloth 17 ′, the core wire 18 ′, and the intermediate canvas 21 ′ become the tooth cloth 17, the core wire element 18, and the intermediate canvas 21 in the belt 10.

  In this method, a tooth cloth 17 'impregnated with rubber glue is first preformed into a corrugated shape, and tooth parts 15' and tooth bottom parts 16 'are alternately provided along a predetermined direction on the tooth cloth 17'. It is done. Next, the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ are pressure-bonded and integrated with the pre-formed tooth cloth 17 ′ in this order to prepare a tooth cloth 32 with a pre-formed rubber. At this time, the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ are pressed against each other to be thickly bonded to the tooth portion 15 ′ of the tooth cloth 17 ′, whereas the tooth rubber sheet 12 ′ and the core rubber sheet 14 ′ Is thinly bonded. Further, in the core rubber sheet 14 ′, the short fibers 20 are oriented in the predetermined direction before crimping, but when they are crimped to the tooth cloth 17 ′, they are inclined so as to follow the tooth shape inside the tooth portion 15 ′. It is done.

  Next, a toothed mold 31 used for vulcanization molding of the toothed belt 10 is prepared. The toothed mold 31 has a cylindrical shape, the outer peripheral surface thereof has a shape that matches the shape of the tooth surface of the belt 10, and concave portions 33 and convex portions 34 are alternately provided along the circumferential direction. A tooth cloth 32 with a pre-molded rubber is first wound around the outer peripheral surface of the toothed mold 31 so that each tooth portion 15 ′ is disposed inside each recess 33. Each tooth portion 15 ′ does not normally have a shape that completely coincides with the concave portion 33, and there is a gap between the tooth portion 15 ′ and the concave portion 33.

  Next, the core wire 18 ′ is spirally wound on the core rubber sheet 14 ′ of the pre-formed rubber tooth cloth 32. An intermediate canvas 21 ′ having a predetermined thickness of the first back rubber sheet 13A ′ affixed on the wound core 18 ′, the back rubber sheet 13A ′ is located inside the mold 31 (on the side of the core 18 ′). ). However, the first back rubber sheet 13A ′ is separate from the intermediate canvas 21 ′, and the first back rubber sheet 13A ′ and the intermediate canvas 21 ′ are wound around the core 18 ′ in this order. Also good. At this time, the warp yarn 22 is arranged along the axial direction of the mold 31 and the weft yarn 23 is arranged along the circumferential direction of the mold 31. A second back rubber sheet 13B 'is further wound on the wound intermediate canvas 21'. The toothed mold 31 around which the pre-formed rubber tooth cloth 32 and the like are wound is accommodated in a vulcanizer (not shown). In the vulcanizer, the pre-formed rubber tooth cloth 32 wound around the toothed mold 31 is heated by, for example, steam and vulcanized from the outside to the inside by a vulcanization bag or the like provided in the vulcanizer. Pressed.

  By the pressurization and heating, the rubber sheets 12 ′, 13A ′, 13B ′, and 14 ′ are pressed inward while the fluidity is increased, and the second back rubber sheet 13B ′ is the warp yarn 22 of the intermediate canvas 21 ′. Then, it flows into the inside through the gap of the weft thread 23 and is integrated with the first back rubber sheet 13A ′. As a result, the intermediate canvas 21 'is embedded in the back rubber sheets 13A' and 13B '. Furthermore, the core wire 18 'is also embedded between the back rubber sheet 13A' and the core rubber sheet 14 '. Further, the tooth cloth 17 ′ is pressed by these rubber sheets to have a shape that matches the outer peripheral surface of the mold 31, and the tooth surface of the belt is formed. Here, a part of the short fibers 20 inside the core rubber sheet is further oriented along the thickness direction, and the orientation shown in FIG. 1 is exhibited. Further, each rubber sheet is vulcanized by the pressurization and heating, and each rubber sheet, the tooth cloth 17 ′, the intermediate canvas 21 ′, and the core wire 18 ′ are integrated to form a belt slab 10 ′ as shown in FIG. Is obtained. The belt slab 10 ′ is removed from the toothed mold 31 and cut after polishing, thereby forming the toothed belt 10 (see FIG. 1).

  Examples are shown below as specific examples of the present embodiment, but the present invention is not limited to the following examples.

[Example 1]
A woven fabric woven with a twill weaving of warp and weft 2/2 was prepared as a tooth cloth. In the tooth cloth, the warp yarn is a filament yarn of 110 dtex nylon 66, and the weft yarn is a 280 dtex polyarylate fiber yarn (Vectran (trade name, manufactured by Kuraray Co., Ltd.) around a core yarn made of urethane elastic yarn of 470 dtex. ) And a cover yarn made of 110 dtex nylon 66 was further wound around the polyarylate fiber yarn. Next, the tooth cloth was dipped in a rubber paste having the rubber composition shown in Table 1, and then dried (100 ° C., 5 minutes) and impregnated. For rubber paste, additives other than the vulcanizing agent and rubber components are kneaded at 120 ° C or higher (primary kneading), and then the vulcanizing agent is added and kneaded below the vulcanizing temperature of the vulcanizing agent to obtain a rubber composition. Obtained (secondary kneading), MEK and phenol resin were added to the rubber composition. In the rubber paste, the weight ratio of rubber composition: phenol resin: MEK was 100: 33: 500.

※ ＨＮＢＲのゴム成分としてZetpol 2020（商品名．日本ゼオン社製）を、ＨＤＰＥ（高密度ポリエチレン）としてインヘンス（ＩＮＨＡＮＣＥ）ＰＥＦファイバー（商品名．フルオロシール社製）を使用した。表１における各数値は重量部を示す。

* Zetpol 2020 (trade name, manufactured by Nippon Zeon Co., Ltd.) was used as the rubber component of HNBR, and INHANCE PEF fiber (trade name, manufactured by Fluoroseal Co., Ltd.) was used as HDPE (high density polyethylene). Each numerical value in Table 1 indicates parts by weight.

  A back rubber sheet (first and second back rubber sheets), a core rubber sheet, and a tooth rubber sheet made of the rubber composition shown in Table 2 were prepared. The tooth rubber sheet was obtained by calendering a rubber composition kneaded in the same manner as the rubber paste. Further, aramid short fibers having a fiber length of 1 mm were blended in the core rubber sheet, and the modulus of the core rubber sheet was higher than those of the first and second back rubber sheets and the tooth rubber sheet. A tooth cloth was preformed, and a tooth rubber sheet and a core rubber sheet were pressure-bonded to the tooth cloth to obtain a tooth cloth with a pre-formed rubber.

※１ 表中において、ＨＮＢＲ／(ＨＮＢＲ＋ジメタクリル酸亜鉛)、ジメタクリル酸亜鉛／(ＨＮＢＲ＋ジメタクリル酸亜鉛)はこれらの比率を、それ以外は重量部であることを示す。
※２ ＨＮＢＲポリマーは水素添加率９９％のＨＮＢＲであった。
※３ ジメタクリル酸亜鉛含有ポリマー（１）は、ＨＮＢＲとジメタクリル酸亜鉛の配合比が５５：４５のゴムマトリックスであり、ＨＮＢＲの水素添加率は９９％であった。
※４ ジメタクリル酸亜鉛含有ポリマー（２）は、ＨＮＢＲとジメタクリル酸亜鉛の配合比が８３：１７のゴムマトリックスであり、ＨＮＢＲの水素添加率は９６％であった。
※５ ＨＤＰＥとして、インヘンス（ＩＮＨＡＮＣＥ）ＰＥＦファイバー（商品名．フルオロシール社製）を使用した。

* 1 In the table, HNBR / (HNBR + zinc dimethacrylate) and zinc dimethacrylate / (HNBR + zinc dimethacrylate) indicate these ratios, and the others are parts by weight.
* 2 HNBR polymer was HNBR with a hydrogenation rate of 99%.
* 3 Zinc dimethacrylate-containing polymer (1) was a rubber matrix having a blending ratio of HNBR and zinc dimethacrylate of 55:45, and the hydrogenation rate of HNBR was 99%.
* 4 Zinc dimethacrylate-containing polymer (2) was a rubber matrix having a mixing ratio of HNBR and zinc dimethacrylate of 83:17, and the hydrogenation rate of HNBR was 96%.
* 5 As the HDPE, INHANCE PEF fiber (trade name, manufactured by Fluoroseal) was used.

  Next, the pre-molded rubber tooth cloth, the core wire, the intermediate canvas with the first back rubber sheet attached thereto, and the second back rubber sheet were wound around the tooth mold in this order. As the intermediate canvas, weaving a weaving nylon yarn of 470 dtex made of nylon 66 and a woven fabric in which a warp yarn of 440 dtex made of twisted yarn of aramid fiber (trade name: Technora HM, manufactured by Teijin Techno Products Co., Ltd.) is used. Were arranged along the circumferential direction of the mold. The elastic modulus in the warp direction (corresponding to the width direction of the belt) of the intermediate canvas before being wound around the mold was 100 GPa. Subsequently, a rubber sheet or the like attached to the mold was vulcanized and molded by heating and pressurizing in a vulcanizing pot to obtain a belt slab. The belt slab was ground and cut to obtain a RU-type toothed belt having a belt width of 16 mm, a circumferential length of 900 mm, and 92 teeth.

[Examples 2 to 4]
Examples 2 to 4 were carried out in the same manner as in Example 1 except that the weight parts of the high-density polyethylene blended in the rubber paste were changed as shown in Table 1.

[Example 5]
The same procedure as in Example 4 was performed except that NBR was used instead of HNBR as the rubber component of the rubber paste.

[Comparative Example 1]
The same operation as in Example 1 was performed except that high-density polyethylene was not blended in the rubber paste.

[Comparative Example 2]
The same operation as in Example 1 was performed except that 10 parts by weight of the high-density polyethylene blended in the rubber paste was used.

[Comparative Example 3]
The same procedure as in Comparative Example 1 was performed except that NBR was used instead of HNBR as the rubber component of the rubber paste.

About the tooth cloth which gave the rubber paste impregnation process of each Example and the comparative example, the dynamic friction coefficient was measured with the friction test apparatus TYPE: 14FW made from Shinto Kagaku. The results are shown in Table 3. The measurement conditions were a single mode, a moving speed of 500 mm / min, and a load of 200 g.

  The adhesive strength between the tooth cloth and the tooth rubber layer according to Examples 1 to 5 and Comparative Examples 1 to 3 was evaluated by an adhesive strength test. As shown in FIG. 4, in this test, a tooth cloth was placed on an unvulcanized rubber sheet, and vulcanized at 160 ° C. for 20 minutes while applying pressure by a press machine, and these were integrated. An adhesion test sample 50 was used. The adhesion test sample 50 had a length of 100 mm, a width of 25 mm, and a thickness of 4 mm. For the unvulcanized rubber sheet in this test, a rubber composition having the same composition as the tooth rubber layer of each example and comparative example was used, and the tooth cloth was impregnated in the same manner as in each example and comparative example. A cloth was used.

  FIG. 5 shows a state in which the adhesion test sample is attached to a tensile tester. As shown in FIG. 5, in the adhesion test sample 50, the tooth cloth 52 and the rubber sheet 51 are slightly peeled off, the end of the tooth cloth 52 is sandwiched between the chucks 61, and the end of the rubber sheet 51 is sandwiched between the chucks 62. These were peeled off by pulling them at a speed of 50 mm / min. The force required for peeling at this time was defined as adhesive strength. The adhesive strength test was performed in a high temperature environment of 120 ° C. The result of the adhesive strength test is shown in FIG.

  FIG. 7 is a layout showing an example of a transmission system in an internal combustion engine. Using this transmission system, a durability performance test was performed on the toothed belts of Examples 1 to 5 and Comparative Examples 1 and 2 described above. The transmission system 40 includes a pulley 41 with a driving tooth of 20 teeth and a diameter of 60 mm connected to a crankshaft, pulleys 42 and 43 with a tooth of 40 teeth and a diameter of 121 mm connected to a camshaft, and a flat tensioner having a diameter of 80 mm. It has a pulley 44. The toothed belt 10 was installed on the pulleys 41 to 43 and rotated at 4000 rpm in a state where tension was applied from the outer peripheral side by the tensioner pulley 44 on the loose side of the belt, and the time until the belt was damaged was measured. The test was performed in an atmosphere at 120 ° C. For each example and comparative example, the time when the belt is broken is shown in FIG. However, regarding Examples 2 to 5, the belt operation was stopped when 200 hours passed before the belt was damaged.

  As is clear from FIG. 8, Example 1 in which 15 to 40 parts by weight of high density polyethylene was blended compared to Comparative Examples 1 and 2 in which HNBR rubber paste was not blended with high density polyethylene or 10 parts by weight. It can be understood that -4 has improved durability under a high temperature environment. In particular, as is apparent from Table 3 and FIGS. 6 and 8 in this evaluation, it can be understood that when 24 to 32 parts by weight of high density polyethylene was blended, the adhesive strength, the friction coefficient, and the durability were good. Furthermore, with respect to Comparative Example 3 and Example 5 using NBR as the rubber component of the rubber paste, Example 5 to which high-density polyethylene was added had better adhesive strength and friction coefficient than Comparative Example 3, It can be understood that the durability of Example 5 was improved.

DESCRIPTION OF SYMBOLS 10 Toothed belt 11 Belt main body 12 Tooth rubber layer 13 Back rubber layer 14 Core rubber layer 15 Tooth part 16 Tooth bottom part 17 Tooth cloth 18 Core element 20 Short fiber 21 Intermediate canvas

Claims (5)

A belt main body formed from rubber, with tooth portions and tooth bottom portions provided alternately along the longitudinal direction on one surface;
A tooth cloth coated on the one surface,
The tooth cloth is impregnated with rubber paste containing 15 to 40 parts by weight of high-density polyethylene with respect to 100 parts by weight of the rubber component,
Average molecular weight of the high density polyethylene is a 300,000～400,000, specific gravity Ri der 0.92 to 0.96,
The toothed belt , wherein the rubber paste is mixed with the rubber component and the high-density polyethylene at a temperature equal to or higher than a deflection temperature under load of the high-density polyethylene .   The toothed belt according to claim 1, wherein the rubber paste includes HNBR or NBR.   The toothed belt according to claim 1, wherein the rubber that forms part of the belt body and is bonded to the tooth cloth includes high-density polyethylene.   The toothed belt according to claim 1, wherein the rubber that forms a part of the belt main body and is bonded to the tooth cloth includes HNBR. The toothed belt according to claim 1, wherein the toothed belt is used in an internal combustion engine.

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