JP4685888B2 - Transmission belt - Google Patents

Description

  The present invention relates to a transmission belt, and more particularly to a transmission belt with improved adhesion between a core wire and an adhesive rubber layer.

  In recent years, the ambient temperature around the engine room of automobiles has risen compared to the conventional environment due to social demands for energy saving and downsizing. In connection with this, it has been pointed out that the operating environment temperature of the power transmission belt increases and the life of the belt decreases. That is, conventionally, rubber materials such as natural rubber, styrene-butadiene rubber, and chloroprene rubber have been used for power transmission belts, but the problem is that the compressed rubber layer hardens and cracks are likely to occur early in a high temperature atmosphere. It is what you did.

  To improve the heat resistance of chloroprene rubber for such an early failure phenomenon of the belt, the improvement of the heat resistance of chloroprene rubber has been studied. An ethylene-α-olefin elastomer such as (EPDM) has been attracting attention as a polymer that has excellent heat resistance and cold resistance, is relatively inexpensive, and has a low content of environmentally hazardous substances. This polymer is also being studied for use in a transmission belt, and is disclosed, for example, in JP-A-6-345948.

  However, ethylene-propylene rubber has a low tearing force, and when a peroxide cross-linking system is used, there is a problem that the tearing force is further reduced and the core wire is likely to pop out during running. On the other hand, it is difficult to sufficiently increase the degree of vulcanization in the case of using a sulfur cross-linking system, and thus wear during running increases. In particular, in a V-ribbed belt, wear powder accumulates at the bottom between ribs and causes adhesive wear. This was a big problem that caused pronunciation. In addition, when EPDM having an extremely large amount of double bonds in the molecule is used to increase the degree of vulcanization, the adhesive wear can be improved to some extent, but there is a problem that the heat resistance is lowered.

  Further, there is a problem in the bonding method between the ethylene / α-olefin elastomer and the fiber cord. Specifically, the fiber material is dipped in a dip solution containing resorcin-formalin-styrene-butadiene-vinylpyridine latex, and then vulcanized and bonded to the EPDM rubber composition (see Patent Document 1). A method of vulcanizing and bonding an EPDM rubber composition blended with a fiber material bonded with a formalin-rubber latex adhesive solution and a methylene donor, a methylene acceptor and a silicic acid compound (see Patent Document 2) has been tried. . In addition, an adhesive treatment agent for ethylene / α-olefin elastomer containing a halogenated polymer is put on the market. In addition, after the fiber is adhered with a resorcin-formalin-rubber latex solution composed of an ethylene / α-olefin elastomer latex, an unvulcanized rubber composition of ethylene / α-olefin rubber is dissolved in a solvent. An ethylene / α-olefin rubber used in a resorcin-formalin-rubber latex solution (RFL solution) in a method for producing an adhesive body of an ethylene / α-olefin rubber composition and fibers that have been overcoated and closely vulcanized An adhesion treatment method in which the total of the diene content of ethylene and the diene content of ethylene / α-olefin used in the overcoat solution is 15% by weight or more has also been proposed. (Patent Document 3)

Japanese Patent Application Laid-Open No. 8-113657 Japanese Patent Application Laid-Open No. 8-113656 JP 2002-88658 A

  However, when treated with a dipping solution containing resorcin-formalin-styrene-butadiene-vinylpyridine latex, the adhesive force is improved, but this is applied to a portion that undergoes repeated bending fatigue such as the core of the transmission belt. When used, the core wire and the adhesive rubber layer sometimes peeled off early.

  In addition, even when an EPDM rubber composition blended with a methylene donor, a methylene acceptor and a silicate compound is used, the core wire and the adhesive rubber layer will be peeled off at an early stage when used in a portion that is repeatedly subjected to bending fatigue. was there.

  Furthermore, the halogenated polymer contained in the adhesive agent for ethylene / α-olefin elastomer is known as an environmentally hazardous substance, and is not preferable in recent years when the importance of environmental problems increases.

  In addition, the adhesiveness is improved by defining the diene content of the ethylene / α-olefin rubber used in the RFL and overcoat treatment liquid, but the effect is that two or more stages of the adhesion treatment are essential, so that the process is simplified. There is room for further improvement from the viewpoint.

  In consideration of these points, an object of the present invention is to provide a transmission belt having improved adhesion between a core wire and an adhesive rubber layer.

  That is, the invention according to claim 1 of the present invention is a transmission belt comprising an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt and an elastic body layer including a compression rubber layer. Adhesion treatment in which 100 parts by mass of 20% ethylene / α-olefin-diene copolymer rubber latex is mixed with 5 to 25 parts by mass of a fatty acid or / and a fatty acid derivative as a processing aid and 10 to 20 parts by mass of an isocyanate compound. A cord having a film formed of an agent is embedded in an adhesive rubber layer made of an ethylene / α-olefin rubber composition.

  The invention according to claim 2 of the present application is the transmission belt according to claim 1, wherein the core wire is impregnated with a pretreatment agent containing isocyanate or / and epoxy.

  The invention according to claim 3 of the present application is the transmission belt according to claim 1 or 2, wherein the processing aid is stearic acid.

  Invention of Claim 4 of this application is a transmission belt in any one of Claim 1 thru | or 3, Comprising: A transmission belt puts a fiber code | cord | chord in an ethylene-alpha-olefin rubber composition along a belt length direction. It is a V-ribbed belt having a buried adhesive rubber layer and a plurality of rib portions extending in the belt length direction made of an ethylene / α-olefin rubber composition.

As described above, the invention described in the claims of the present application has a diene content of 8 as the core wire in the power transmission belt including the adhesive rubber layer in which the core wire is embedded along the longitudinal direction of the belt and the elastic layer including the compression rubber layer. Adhesion of ˜20% ethylene / α-olefin-diene copolymer rubber latex with 5 to 25 parts by weight of fatty acid or / and fatty acid derivative and 10 to 20 parts by weight of isocyanate compound as processing aid A transmission belt characterized in that a cord having a coating formed by a treatment agent is embedded in an adhesive rubber layer made of an ethylene / α-olefin rubber composition, and the adhesive strength between the rubber composition and the core wire is high, and thus The effect of extending the belt running life can be expected.

  The ethylene / α-olefin rubber used in the present invention is a copolymer of ethylene and α-olefin (propylene, butene, hexene, or octene), or a copolymer of ethylene, the α-olefin, and the nonconjugated diene. Specifically, it refers to rubber made of ethylene-propylene rubber (EPM) or ethylene-propylene-diene terpolymer (EPDM). Examples of the diene component include non-conjugated dienes having 5 to 15 carbon atoms such as ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, and methylene norbornene.

  For crosslinking the rubber, sulfur or organic peroxide is used. Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 1,3-bis (t-butylperoxyisopropyl) benzene, 2,5 -Dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5- (benzoylperoxy) hexane, 2,5-dimethyl-2,5-mono (t- Butyl peroxy) hexane and the like. This organic peroxide is usually used alone or as a mixture in the range of 0.005 to 0.02 mol g with respect to 100 g of the ethylene-α-olefin elastomer.

  Further, by adding a co-agent, it is possible to increase the degree of cross-linking and prevent problems such as adhesive wear. Examples of the crosslinking aid include TIAC, TAC, 1,2 polybutadiene, metal salt of unsaturated carboxylic acid, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN′-m- Usually used for peroxide crosslinking such as phenylene bismaleimide and sulfur.

  In addition, other rubber compounds such as enhancers such as carbon black and silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids, and colorants are used as necessary. What is used is used.

  The fibers used in the present invention are polyester fibers such as aramid fibers, polyethylene terephthalate fibers (PET fibers), and polyethylene naphthalate fibers (PEN fibers), and cords and woven fabrics are used as their forms.

The fiber to be used is subjected to adhesion treatment by the following method.
That is, 100 parts by mass of an ethylene / α-olefin-diene copolymer rubber latex having a diene content of 8 to 20%, 5 to 25 parts by mass of a fatty acid or / and a fatty acid derivative as a processing aid, and an isocyanate compound After being overcoated with a rubber paste containing 10 to 20 parts by mass, the rubber is closely vulcanized with an unvulcanized rubber composition of ethylene / α-olefin rubber. In addition, pretreatment with a treatment liquid containing isocyanate or / and epoxy is preferable before the overcoat treatment in order to increase the adhesive force. In the pretreatment, the untreated fibers are immersed in a treatment solution containing isocyanate and / or epoxy set at room temperature for 0.5 to 30 seconds, and then dried by passing through an oven adjusted to 150 to 190 ° C. for 2 to 5 minutes. The

  The ethylene / α-olefin-diene copolymer rubber is a copolymer of ethylene and α-olefin (propylene, butene, hexene, or octene), or a copolymer of ethylene, the α-olefin, and the nonconjugated diene. Specifically, it refers to rubber made of ethylene-propylene rubber (EPM) or ethylene-propylene-diene terpolymer (EPDM). Examples of the diene component include non-conjugated dienes having 5 to 15 carbon atoms such as ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, and methylene norbornene. As the ethylene / α-olefin-diene copolymer rubber, those having a diene content of 8 to 20% are used. If it is less than 8%, no improvement in adhesion is observed, while if it exceeds 20%, the physical properties of rubber are deteriorated.

  There are the following two types of rubber latex production methods. One is a method in which a solid polymer is dissolved in a solvent and then phase-changed and emulsified and dispersed in water to form a latex. The other is emulsified. This is a method in which a monomer is polymerized to obtain a latex as it is. In the examples described later, the ethylene-propylene-diene monomer latex produced by the former method is used, but it may be produced by any method.

  Examples of the isocyanate include 4,4'-diphenylmethane diisocyanate, tolylene 2,4-diisocyanate, polymethylene polyphenyl diisocyanate, hexamethylene diisocyanate, and polyaryl polyisocyanate (for example, PAPI as a trade name). Moreover, the blocked polyisocyanate which blocked the isocyanate group of polyisocyanate by making the said isocyanate react with blocking agents, such as phenol, tertiary alcohol, and secondary alcohol, can also be used. The blending amount is 10 to 20 parts by mass with respect to 100 parts by mass of the ethylene / α-olefin rubber. If it is less than 10 parts by mass, the adhesion with the unvulcanized rubber at high temperature is insufficient, while if it exceeds 20 parts by mass, the adhesive force is reduced.

  As processing aids, fatty acids or / and fatty acid derivatives are used. Specific examples include higher fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid, oleic acid, and erucic acid, and metal salts, esters, and amides of these fatty acids. be able to. Of these, stearic acid is widely used. In addition to the fatty acid metal salt, it is also preferable to use a processing aid mixed with paraffins and polyvalent carboxylic acid esters in order to increase the adhesiveness. The processing aid improves the dispersibility of the rubber compounding agent and the workability of the rubber composition, and has an adhesive property when the ethylene / α-olefin composition containing the processing aid is used for the overcoat treatment. It is effective for improvement. The blending amount is preferably 5 to 25 parts by mass with respect to 100 parts by mass of ethylene / α-olefin rubber. If the amount is less than 5 parts by mass, the adhesion with the unvulcanized rubber is insufficient. On the other hand, if the amount exceeds 25 parts by mass, the adhesive force is reduced.

  Moreover, silica, carbon black, a vulcanization accelerator, etc. can be included as needed. Silica includes hydrous silica, and the particle diameter, PH, etc. are not limited. The addition amount is 5 to 40 parts by mass with respect to 100 parts by mass of the ethylene / α-olefin rubber. If the amount is less than 5 parts by mass, the adhesion with the unvulcanized rubber is insufficient. On the other hand, if the amount exceeds 40 parts by mass, the viscosity of the rubber increases, the permeability to the fibers is poor, and the adhesive strength decreases.

  The types of carbon black include SAF, ISAF, HAF, FF, FEF, GPF, SRF, FT, and MT, and are not particularly defined. The addition amount is 5 to 50 parts by mass with respect to 100 parts by mass of the ethylene / α-olefin rubber. If the amount is less than 5 parts by mass, the decrease in the adhesive strength of the treated fibers over time is large.

  An initial condensate of resorcin and formalin may be added. In this case, the molar ratio of resorcin to formalin is preferably 1: 2 to 2: 1 in order to increase the adhesive force. If the molar ratio is less than 1/2, the three-dimensional reaction of resorcin-formalin resin progresses too much and gels, while if it exceeds 2/1, the reaction between resorcin and formalin does not progress so much, resulting in decreased adhesion. To do.

  The ethylene / α-olefin rubber content in the rubber composition used in the overcoat treatment liquid is 60 to 90% by mass. If the amount is less than 60% by mass, the permeability to the fibers is poor and the adhesive strength is reduced.

  Examples of the isocyanate compound used in the pretreatment liquid include those exemplified above. This isocyanate compound is used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  Examples of the epoxy compound used in the pretreatment liquid include polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol, reaction products of polyalkylene glycols such as polyethylene glycol and halogen-containing epoxy compounds such as epichlorohydrin, and resorcinol. Bis (4-hydroxyphenyl) dimethylmethane, phenol. Formaldehyde resin, resorcin. Reaction products with polyhydric phenols such as formaldehyde resins and halogen-containing epoxy compounds. The epoxy compound is used by mixing with an organic solvent such as toluene or methyl ethyl ketone.

  As an application of the fiber subjected to the above-described adhesion treatment, for example, it is used for a core of a V-ribbed belt shown in FIG. According to this V-ribbed belt 1, a core wire 2 made of a high-strength, low-stretch cord made of a twisted cord in the adhesive rubber layer 3 is embedded in the adhesive rubber layer 3, and an elastic body layer is provided below the cord 2. It has a certain compressed rubber layer 4. The compressed rubber layer 4 is provided with a plurality of ribs 7 having a substantially triangular cross section extending in the longitudinal direction of the belt. Further, the rubber-equipped canvas 5 may be provided on the belt surface, but need not be provided.

  The rubber composition used for the compressed rubber layer 4 is 1 to 50 parts by mass, preferably 5 to 5 parts by mass of short fibers such as aramid, nylon, polyester, vinylon and cotton with respect to 100 parts by mass of ethylene / α-olefin rubber. You may contain 25 mass parts.

  On the other hand, the adhesive rubber layer 3 is made of the above-mentioned ethylene / α-olefin rubber composition that can be cross-linked with sulfur in order to have heat resistance and to improve the adhesion with the core wire. And other than that, it is used for usual rubber compounding such as carbon black and reinforcing agents such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids and colorants. Things are used.

  The amount of sulfur added in the adhesive rubber layer 3 is 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the ethylene / α-olefin rubber.

  Of the ethylene / α-olefin rubber used for the adhesive rubber layer 3, EPDM preferably has an iodine value of 4 or more and less than 40. If it is less than 4, crosslinking of the rubber composition with sulfur is not sufficient, and the problem of core wire pop-out occurs. On the other hand, if it exceeds 40, the scorch of the rubber composition becomes short and difficult to handle, and the heat resistance deteriorates.

  An example of the manufacturing method of the V-ribbed belt is as follows. First, one or more cover canvases and an adhesive rubber layer are wound around the circumferential surface of a cylindrical molding drum, and then a cord made of a rope is spun spirally thereon, and further a compressed rubber layer is wound in order. After being attached to obtain a laminated body, this is crosslinked with sulfur or an organic peroxide to obtain a crosslinked sleeve.

  Next, the bridging sleeve is hung between the driving roll and the driven roll and travels under a predetermined tension, and the rotated grinding wheel is moved so as to abut on the traveling bridging sleeve and the compressed rubber layer surface of the bridging sleeve 3 to 100 grooves are simultaneously polished.

  The thus obtained bridging sleeve is removed from the driving roll and the driven roll, the bridging sleeve is hung on the other driving roll and the driven roll, traveled, cut into a predetermined width by a cutter, and each V-ribbed belt. Finish.

  In addition to the above-mentioned V-ribbed belt, the present invention also includes a transmission belt such as a V-belt 21 in which rubber canvas 25 is attached only to the upper and lower surfaces of the belt as shown in FIG. This V-belt 21 has a core wire 22 embedded in an adhesive rubber layer 23, and a compression rubber layer 24, which is an elastic layer, on the lower side thereof. The compressed rubber layer 24 may be provided with cogs at predetermined intervals along the longitudinal direction.

Hereinafter, the present invention will be described in more detail with reference to examples.
Examples 1-4, Comparative Examples 1-4
An untreated twisted cord of 1220 dtex / 1 × 5 polyethylene terephthalate (PET) was prepared, immersed in the predip solution shown in Table 1, and then heat treated at 180 ° C. for 4 minutes. Next, it was immersed in the overcoat treatment liquid shown in Table 5 and heat-treated at 150 ° C. for 4 minutes. The overcoat treatment solution was prepared by dissolving the compounded rubber and the isocyanate shown in Table 2 in toluene.

  The obtained cord was placed 25 mm wide on a 4 mm thick rubber sheet having the composition shown in Table 3, applied with a pressure of 2.0 MPa with a press plate, vulcanized at 163 ° C. for 30 minutes, and used for a peel test. A sample was prepared. And peeling force was measured according to JISK6256. The results are shown in Table 6. In addition, the stearic acid compounding amount and isocyanate compounding amount in Table 6 refer to each compounding amount with respect to 100 parts by mass of the EPDM rubber component in the overcoat treatment liquid.

  Moreover, the obtained process cord was made into a core wire, the rubber compounding of Table 4 was prepared as an adhesive rubber layer, and the rubber compounding of Table 3 was prepared as a compression rubber layer. Then, two plies of rubberized cotton canvas and an adhesive rubber layer are laminated on the peripheral surface of the cylindrical molding drum, and the core wire is pinned at a pitch of 1.03 mm and a tension of 50 N, and then a compressed rubber layer is laminated. The product was vulcanized. While the vulcanization sleeve is hung on the driving roll and driven roll and running under a predetermined tension, the rotating grinding wheel is applied to the surface of the compressed rubber layer to polish a plurality of grooves, and to a predetermined width A V-ribbed belt was obtained by cutting.

  The obtained V-ribbed belt is a K-type 3-ribbed belt having a length of 975 mm according to the RMA standard, and has a rib pitch of 3.56 mm, a rib height of 2.0 mm, a belt thickness of 4.3 mm, and a rib angle of 40 °. As an evaluation of the adhesion of the obtained belt, two core wires embedded in the belt circumferential direction were caused, and the stress when peeled at a speed of 50 mm / min was determined. The results are also shown in Table 6.

  As a result, although sufficient adhesiveness was obtained in the examples, it was found that in Comparative Example 1 using EPDM having a diene content of 5%, the adhesiveness was low even when a suitable amount of stearic acid and isocyanate were blended. On the other hand, even when EPDM having a diene content of 12.5% is used, it can be seen that Comparative Examples 2 and 3 in which appropriate amounts of stearic acid and isocyanate are not mixed have difficulty in adhesion.

It is sectional drawing of a V-ribbed belt.

It is sectional drawing of a V belt.

Explanation of symbols

1 V-ribbed belt 2 Core wire 3 Adhesive rubber layer 4 Compression rubber layer 5 Rubberized canvas 7 Rib

Claims (4)

In a power transmission belt comprising an adhesive rubber layer in which a core wire is embedded along the longitudinal direction of the belt and an elastic layer including a compression rubber layer, an ethylene / α-olefin-diene having a diene content of 8 to 20% as the core wire A cord having a film formed of an adhesive treatment agent in which 5 to 25 parts by mass of a fatty acid or / and a fatty acid derivative as a processing aid and 10 to 20 parts by mass of an isocyanate compound is blended with 100 parts by mass of a copolymer rubber latex, A power transmission belt embedded in an adhesive rubber layer made of an α-olefin rubber composition. The power transmission belt according to claim 1, wherein the core wire is impregnated with a pretreatment agent containing an isocyanate compound and / or an epoxy compound. The power transmission belt according to claim 1 or 2, wherein the processing aid is stearic acid. The transmission belt has a plurality of adhesive rubber layers in which fiber cords are embedded in the ethylene / α-olefin rubber composition along the belt length direction and a belt length direction made of the ethylene / α-olefin rubber composition. The transmission belt according to claim 1, wherein the transmission belt is a V-ribbed belt having a plurality of rib portions.

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