JP2010169215A - Frictional transmission belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frictional transmission belt capable of preventing the early occurrence of core wire popping-out by improving the tear resistance and bending crack resistance of an adhesive rubber layer. <P>SOLUTION: The frictional transmission belt includes the adhesive rubber layer 3 with core wires 2 embedded. The adhesive rubber layer 3 is formed of a rubber composition containing ethylene-α-olefin elastomer, 2-20 pts.mass of novolac-type thermosetting phenol resin to 100 pts.mass of ethylene-α-olefin elastomer, and a curing agent. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a friction transmission belt used for power transmission.

  The friction transmission belt is generally formed of a compression rubber layer on the inner peripheral side of the belt and an adhesive rubber layer embedded in the core wire and laminated on the outer periphery of the compression rubber layer. Conventionally, chloroprene rubber or the like is generally used as the rubber for forming the compressed rubber layer, the adhesive rubber layer, and the like. However, when the friction transmission belt is used at a high ambient temperature as in an engine room of an automobile, there is a problem that chloroprene rubber having low heat resistance may cause cracking and cannot be used.

  In contrast, ethylene-α-olefin elastomers such as ethylene-propylene-diene terpolymers are known to exhibit excellent heat resistance and cold resistance, and therefore friction transmission belts used in high-temperature atmospheres are known. Preparation with such an ethylene-α-olefin elastomer has been carried out.

  For example, Patent Document 1 discloses that a rubber composition containing an ethylene-α-olefin elastomer is used to form a compression rubber layer or an adhesive rubber layer of a friction transmission belt, and a core wire embedded in the adhesive rubber layer is a carboxylated vinylpyridine. It is disclosed to perform an adhesion treatment with a resorcin-formalin-latex containing latex.

JP 2006-300104 A

  As mentioned above, ethylene-α-olefin elastomer has higher heat resistance than chloroprene rubber, etc., so it is possible to obtain a friction transmission belt that can withstand use in a high-temperature atmosphere, but with regard to tear resistance and flex crack resistance, There is a problem that it is inferior to chloroprene rubber.

  For this reason, when the adhesive rubber layer in which the core wire is embedded is formed of a rubber composition containing an ethylene-α-olefin elastomer, the core wire embedded from the side end surface of the adhesive rubber layer pops out, so-called core pop-out. The problem of occurring occurred.

  In the above-mentioned Patent Document 1, the adhesive force of the core wire can be increased by bonding the core wire with resorcin-formalin-latex containing carboxylated vinylpyridine latex, and the core wire can be prevented from popping out. Although effective, it is not enough. In particular, the adhesive rubber layer itself does not have improved tear resistance or flex crack resistance, so when running a friction transmission belt using a small-diameter pulley, cord pop-out may occur at an early stage. It was.

  The present invention has been made in view of the above points, and provides a friction transmission belt capable of improving the tear resistance and bending crack resistance of an adhesive rubber layer and preventing the occurrence of early core pop-out. It is intended to do.

  The friction transmission belt according to the present invention is a friction transmission belt including an adhesive rubber layer in which a core wire is embedded, and is 2 to 20 parts by mass with respect to 100 parts by mass of the ethylene-α-olefin elastomer and the ethylene-α-olefin elastomer. An adhesive rubber layer is formed of a rubber composition containing a novolac-type thermosetting phenol resin and a curing agent.

  Thus, by forming an adhesive rubber layer with a rubber composition in which a novolac-type thermosetting phenol resin is blended with an ethylene-α-olefin elastomer, the rubber hardness of the adhesive rubber layer is increased and rubber deformation can be suppressed. It can improve the tear resistance and bending crack resistance of the adhesive rubber layer, and can prevent the occurrence of core pop-out that the core wire embedded in the adhesive rubber layer jumps out from the side end face. is there.

  Moreover, in this invention, 0.2-2 mass parts sulfur is mix | blended with the said rubber composition with respect to 100 mass parts of ethylene-alpha-olefin elastomers, It is characterized by the above-mentioned.

  By blending sulfur in this way, the crosslink density of the ethylene-α-olefin elastomer can be increased, the rubber hardness of the adhesive rubber layer can be increased, and the occurrence of cord popout can be more effectively prevented. .

  In the present invention, the friction transmission belt can be formed as a V-ribbed belt.

  According to the present invention, by forming an adhesive rubber layer with a rubber composition in which a novolak-type thermosetting phenol resin is blended with an ethylene-α-olefin elastomer, the rubber hardness of the adhesive rubber layer is increased and rubber deformation is suppressed. Can improve the tear resistance and flex crack resistance of the adhesive rubber layer, and can prevent early pop-out from occurring in the core wire embedded in the adhesive rubber layer It is.

It is the partially broken perspective view which shows a V-ribbed belt.

  Embodiments of the present invention will be described below.

  The rubber composition for forming the adhesive rubber layer is prepared by containing an ethylene-α-olefin elastomer, a novolac thermosetting phenol resin, and a curing agent as essential components.

  As said ethylene-alpha-olefin elastomer, ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer (EPDM), etc. can be used, These are used independently or these mixtures are used. be able to. Examples of the diene monomer of EPDM include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like. In view of heat resistance and wear resistance, EPDM which is a copolymer of ethylene, α-olefin and non-conjugated diene is preferable. Among them, ethylene content is 51 to 68% by mass and double bond is 0. The thing of 2-7.5 mass% is preferable. As this EPDM, it is preferable to use one having an iodine value of 3 to 40. If the iodine value is less than 3, the rubber composition is not sufficiently vulcanized, and there is a possibility that problems of wear and adhesion occur. On the other hand, when the iodine value exceeds 40, the scorch of the rubber composition becomes short and difficult to handle, and the heat resistance may be deteriorated.

  Examples of the novolak-type thermosetting phenol resin include an unmodified phenol resin prepared by condensing phenol and formaldehyde, an alkyl-substituted phenol resin, and an oil-modified phenol resin. Here, the alkyl-substituted phenol resin is a resin using other alkyl phenols such as cresol, xylenol and octyl phenol instead of phenol, and the oil-modified phenol resin is modified with various oils such as cashew nut oil, tall oil and rosin oil. Resin.

  Further, the curing agent described above is for curing a novolac type thermosetting phenol resin to form a three-dimensional crosslinked structure, and for example, hexamethylenetetramine, hexamethoxymethylmelamine, or the like can be used.

  And the rubber composition which forms an adhesive rubber layer can be obtained by mix | blending and knead | mixing a novolak-type phenol resin and a hardening | curing agent to this, using ethylene-alpha-olefin elastomer as a rubber component. The rubber composition further contains a crosslinking agent such as sulfur, a reinforcing agent such as carbon black and silica, a filler such as calcium carbonate and talc, a reinforcing agent, a plasticizer, a stabilizer, a processing aid, if necessary. You may make it mix | blend a coloring agent, a short fiber, etc. Moreover, the method of kneading these various blends is not particularly limited, and examples thereof include a method of kneading using commonly used means such as a Banbury mixer and a kneader.

  FIG. 1 shows an example of a friction transmission belt. Examples of the friction transmission belt include a V-ribbed belt, a V-belt, and a flat belt. FIG. In FIG. 1, reference numeral 2 denotes a core wire, which is embedded in the adhesive rubber layer 3 over the entire length in the belt longitudinal direction. A compression rubber layer 4 is laminated inside the adhesive rubber layer 3, and a plurality of parallel rib portions 5 are formed on the compression rubber layer 4. The rib portion 5 has a substantially V-shaped cross section (more precisely, a trapezoidal shape), and is provided over the entire length in the belt longitudinal direction. An extension layer 6 is laminated outside the adhesive rubber layer 2.

  As the core 2, polyester fiber such as polyarylate fiber, polybutylene terephthalate (PBT) fiber, polyethylene terephthalate (PET) fiber, polytrimethylene terephthalate (PTT) fiber, polyethylene naphthalate (PEN) fiber, aramid fiber, glass A high strength and low elongation cord formed of fibers or the like can be used. The core 2 is preferably subjected to an adhesion treatment for the purpose of improving the adhesion to rubber. Such an adhesion treatment can be performed by immersing the core wire 2 in a treatment liquid such as a resorcinol-formaldehyde-latex liquid (RFL liquid) and drying it by heating.

  The adhesive rubber layer 3 and the compressed rubber layer 4 are made of rubber. Of the adhesive rubber layer 3 and the compressed rubber layer 4, the adhesive rubber layer 3 is made of the above rubber composition. The compressed rubber layer 4 is also formed of a rubber composition containing an ethylene-α-olefin elastomer as a rubber component, and short fibers such as nylon (registered trademark), p-aramid, and m-aramid are added to the rubber composition. By containing, the short fiber is projected on the surface of the rib portion 5 of the compressed rubber layer 4.

  The stretch layer 6 is formed of a reinforcing cloth such as canvas. As this reinforcing cloth, a cloth woven in plain, twill, or satin weaving cotton, polyester fiber, aramid fiber, nylon fiber or the like can be used. After the RFL treatment is applied to the reinforcing cloth, rubber is coated. It is preferably used as a rubberized canvas.

  Next, an example of a method for manufacturing the V-ribbed belt 1 as described above will be described. First, a reinforcing cloth for forming the stretch layer 6 is wound around the outer periphery of a cylindrical molding drum, and a sheet of a rubber composition for forming the adhesive rubber layer 3 is wound thereon, and then the core 2 is spun on this. Then, a non-vulcanized sleeve is produced by winding in a spiral shape and winding a sheet of the rubber composition forming the compressed rubber layer 4 thereon. Next, the unvulcanized sleeve wound around the forming drum is placed in a vulcanizing drum and vulcanized to obtain a cylindrical vulcanized sleeve. Thereafter, the vulcanized sleeve is suspended between the driving roll and the driven roll and rotated and rotated, and the rotated cutting wheel is brought into contact with the compressed rubber layer 4 on the outer periphery of the vulcanized sleeve to cut a large number of V grooves. -The rib part 5 used as a friction transmission surface is formed by grinding | polishing. The V-ribbed belt 1 as shown in FIG. 1 can be finished by cutting the vulcanization sleeve with a predetermined width dimension so as to be cut and turning the inner circumference and the outer circumference.

  In the friction transmission belt manufactured as described above, the adhesive rubber layer 3 in which the core wire 2 is embedded is formed of a rubber composition in which a novolac-type thermosetting phenol resin is blended with an ethylene-α-olefin elastomer. The novolak type thermosetting phenol resin is cured by a curing agent by heating at the time of crosslinking to form a three-dimensional crosslinked structure. For this reason, the adhesive rubber layer 3 has a moderately increased rubber hardness and suppresses deformation of the rubber, and can improve the tear resistance and the bending crack resistance of the adhesive rubber layer 3. Accordingly, even when the friction transmission belt is run using a small-diameter pulley, the adhesive rubber layer 3 is prevented from tearing or cracking to prevent the core pop-out from occurring at an early stage. It is something that can be done. Here, it is possible to increase the rubber hardness by increasing the amount of carbon black, but in this case, since the adhesiveness between the core 2 and the rubber is lowered, it is possible to prevent the occurrence of the core pop-out. In addition, there is a possibility that the dynamic heat generation becomes remarkable due to the large amount of carbon black and the durability of the belt is lowered.

  The compounding quantity of a novolak-type thermosetting phenol resin is set to the range of 2-20 mass parts with respect to 100 mass parts of ethylene-alpha-olefin elastomers. When the blending amount of the novolak type thermosetting phenol resin is less than 2 parts by mass, the rubber hardness of the adhesive rubber layer 3 cannot be sufficiently increased, and the tear resistance and the flex crack resistance of the adhesive rubber layer 3 are improved. Effect is insufficient. On the other hand, when the blending amount of the novolac type thermosetting phenol resin exceeds 20 parts by mass, the flexibility of the adhesive rubber layer 3 is lost, and in this case, the tear resistance and the flex crack resistance of the adhesive rubber layer 3 are improved. I can't.

  Moreover, the compounding quantity of a hardening | curing agent is although it does not specifically limit, The range of 0.2-2 mass parts is preferable with respect to 100 mass parts of novolak type thermosetting phenol resins. In order to appropriately cure the novolac type thermosetting phenol resin and appropriately increase the rubber hardness of the adhesive rubber layer 3, it is preferable to set the blending amount of the curing agent within this range. The curing agent may be separately added to the rubber composition together with the novolac type thermosetting phenol resin, or a novolac type thermosetting phenol resin in which a curing agent is internally added may be used. In this case, it is not necessary to add a curing agent separately.

  Moreover, when sulfur is mix | blended with a rubber composition, the crosslinking density of ethylene-alpha-olefin elastomer is raised, the rubber hardness of the adhesive rubber layer 3 is raised, and generation | occurrence | production of a core wire popout is prevented more effectively. It is something that can be done. The amount of sulfur is preferably in the range of 0.2 to 2 parts by mass with respect to 100 parts by mass of the ethylene-α-olefin elastomer. If the amount of sulfur is less than 0.2 parts by mass, the rubber hardness of the adhesive rubber layer 3 cannot be sufficiently increased, and the effect of improving the tear resistance and flex crack resistance of the adhesive rubber layer 3 is ineffective. On the contrary, if the amount of sulfur exceeds 2 parts by mass, the flexibility of the adhesive rubber layer 3 is lost, and in this case as well, the tear resistance and flex crack resistance of the adhesive rubber layer 3 cannot be improved. .

  Next, the present invention will be specifically described with reference to examples.

  The rubber compositions of Table 1 using EPDM polymer as the ethylene-α-olefin elastomer and hexamethylenetetramine as the curing agent were kneaded with a Banbury mixer, and then rolled with a calender roll, whereby Examples 1 to 7 and Sheets for adhesive rubber layers of Comparative Examples 1 to 3 were prepared.

  Moreover, after knead | mixing the rubber composition of the mixing | blending of Table 2 with a Banbury mixer, the sheet | seat for compression rubber layers was prepared by rolling with a calender roll.

  And using the sheet | seat for adhesive rubber layers of Examples 1-7 of the mixing | blending of Table 1, and Comparative Examples 1-3 and the sheet | seat for compression rubber layers of the mixing | blending of Table 2, and using the rope of a polyester fiber as a cord A V-ribbed belt 1 having the configuration shown in FIG. 1 was produced by the method described above. In this V-ribbed belt 1, a stretched layer 6 is formed by laminating two plies of rubber-coated canvas on one side of an adhesive rubber layer 3 in which a core wire 2 is embedded, and a compressed rubber layer 4 laminated on the other side of the adhesive rubber layer 3. Three rib portions 5 are formed in the longitudinal direction of the belt.

(Tear test)
The sheets for adhesive rubber layers of Examples 1 to 7 and Comparative Examples 1 to 3 in Table 1 were cross-linked by pressing at 165 ° C. for 30 minutes to prepare crescent-type samples defined in JIS K6252. And tear resistance was measured according to JIS K6252.

(Dematcher bending crack test)
The adhesive rubber layer sheets of Examples 1 to 7 and Comparative Examples 1 to 3 in Table 1 were cross-linked by pressing at 165 ° C. for 30 minutes to prepare test pieces defined in JIS K6260. Then, a test was performed according to JIS K6260, and the number of flexing until the crack reached 10 mm was measured.

(High temperature bending fatigue test)
Examples 1 to 7 prepared as described above and a comparison using a traveling test machine in which a driving pulley (diameter 120 mm), an idler pulley (diameter 85 mm), a driven pulley (diameter 120 mm), and a tension pulley (diameter 45 mm) were arranged in order. The V-ribbed belts of Examples 1 to 3 were bridged over each pulley. At this time, the winding angle of the V-ribbed belt around the tension pulley was set at 90 °, and the winding angle around the idler pulley was set at 120 °. Then, with a load of 8.8 kW applied to the driven pulley and a belt load of 80 kgf / 3 applied to the tension pulley, the vehicle was run under the conditions of an ambient temperature of 120 ° C. and a rotational speed of the drive pulley of 4900 rpm. The time until the occurrence of the core pop-out was measured.

  As can be seen from Table 3, those in Examples 1 to 7 have larger tear resistance and improved tear resistance than those of the comparative examples, and the number of flexures achieved with a crack of 10 mm is increased, resulting in flex crack resistance. It was confirmed that the core wire pop-out did not occur for 200 hours in the high-temperature bending fatigue test.

  On the other hand, in Comparative Example 1, since no hexamethylenetetramine, which is a curing agent, is contained, the curing reaction of the novolac thermosetting phenol resin does not occur, and the tear resistance and the flex crack resistance cannot be improved. The mind pop out occurred early.

  In Comparative Example 2, the amount of the novolak-type thermosetting phenolic resin is too small, so that the tear resistance and the flex crack resistance are not sufficiently improved, and the core pop-out occurs early. .

  In Comparative Example 3, the amount of the novolak-type thermosetting phenol resin is too large, so that the flexibility of the rubber composition is lost, resulting in insufficient improvement in tear resistance and flex crack resistance. Line pop out occurred.

1 V-ribbed belt 2 Core wire 3 Adhesive rubber layer

Claims (3)

  In a friction transmission belt including an adhesive rubber layer in which a core wire is embedded, an ethylene-α-olefin elastomer, 2-20 parts by mass of a novolac-type thermosetting phenol resin with respect to 100 parts by mass of the ethylene-α-olefin elastomer, A friction transmission belt comprising an adhesive rubber layer formed of a rubber composition containing a curing agent.   The friction transmission belt according to claim 1, wherein 0.2 to 2 parts by mass of sulfur is blended with 100 parts by mass of the ethylene-α-olefin elastomer in the rubber composition.   The friction transmission belt according to claim 1, wherein the friction transmission belt is a V-ribbed belt.

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