JP2002294178A - Method for bonding rubber compound to fiber cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for bonding an ethylene/α-olefin rubber composition to a fiber cord whereby the ethylene/α-olefin rubber composition can be bonded well to the fiber cord which is used as a core of a transmission belt. SOLUTION: In this bonding method, a fiber cord is treated with a first treating liquid comprising an isocyanate compound and/or an epoxy compound, then with a second treating liquid comprising a resorcin-formalin-rubber latex, and with a third treating liquid containing a halogenated polymer and a vulcanizing agent; then, the unvulcanized ethylene/α-olefin rubber composition is stuck to the treated fiber cord and vulcanized. The pickup of the first treating liquid is 8% or lower. The rubber latex contained in the second treating liquid is a vinylpyridine latex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bonding an ethylene / .alpha.-olefin rubber composition to a fiber cord, and more particularly, to a method for bonding an ethylene / .alpha.-olefin rubber composition and a fiber cord serving as a core of a power transmission belt. The present invention relates to a method for bonding an ethylene / α-olefin rubber composition and a fiber cord, which can bond well.

[0002]

2. Description of the Related Art With the recent demand for energy saving and compactness of automobiles, the ambient temperature around an engine room has been increasing as compared with the related art. As a result, the operating environment temperature of the power transmission belt has increased. Conventionally, natural rubber, styrene-butadiene rubber, and chloroprene rubber have been mainly used as the rubber of the power transmission belt. However, in a high-temperature atmosphere, a problem has occurred in that a crack is generated in the cured compressed rubber layer at an early stage.

[0003] In order to cope with such an early fracture phenomenon of the power transmission belt, improvement of the heat resistance of chloroprene rubber has been conventionally studied. However, instead of this, recently, for example, Japanese Patent Application Laid-Open No. 6-345948 discloses this technique. As
Consider the use of ethylene-α-olefin elastomers such as ethylene-propylene rubber (EPR) or ethylene-propylene-diene rubber (EPDM), which is a relatively inexpensive polymer that has excellent heat resistance and cold resistance. Is being done.

[0004] However, the ethylene-propylene rubber has a low tear resistance, and when a peroxide vulcanization system is used, the tear resistance is further reduced, and there is a problem that the core wire tends to pop out during running. On the other hand, in the case of using a sulfur vulcanization system, it is difficult to sufficiently increase the degree of vulcanization, so that abrasion increases during running. It was prone to wear, which was a major problem causing pronunciation. Also,
When EPDM having an extremely large amount of double bonds in the molecule is used to increase the degree of vulcanization, the problem that adhesive heat is improved to some extent but heat resistance is lowered occurs.

[0005] In addition to the above-mentioned problem of the rubber composition alone, there is also a problem of a method of bonding the ethylene-α-olefin elastomer to a fiber cord to be a core wire. As a specific countermeasure, the fiber cord is resorcinol-formalin-NB
After dipping in a dip solution containing R latex,
A method of vulcanizing and bonding with an EPDM rubber composition, and vulcanizing and bonding with an EPDM rubber composition blended with a fiber cord bonded with a resorcinol-formalin-rubber latex bonding solution, a methylene donor, a methylene acceptor and a silicate compound Methods have been studied.

[0006]

However, resorcinol-
In the method using a dip solution containing formalin-NBR latex, there was a problem that even if the adhesive strength was improved, it was early lowered due to repeated bending fatigue. Further, even when an EPDM rubber composition mixed with a methylene donor, a methylene acceptor and a silicate compound is used, there is a problem that the core wire and the adhesive rubber layer are separated at an early stage.

The present invention pays attention to these problems, and provides an ethylene / α-olefin rubber composition capable of favorably bonding an ethylene / α-olefin rubber composition to a fiber cord serving as a core wire of a power transmission belt. It is an object of the present invention to provide a bonding method between a fiber cord and a fiber cord.

[0008]

According to a first aspect of the present invention, there is provided a method of bonding an ethylene / α-olefin rubber composition and a fiber cord, wherein the fiber cord is made of an isocyanate compound and / or an epoxy compound.
Treatment with a treatment liquid, then with a second treatment liquid of resorcinol-formalin-rubber latex, followed by treatment with a third treatment liquid in which a vulcanizing agent is added to a halogenated polymer, followed by ethylene / α-olefin rubber A method for bonding an ethylene / α-olefin rubber composition to a fiber cord, wherein the uncured rubber composition is tightly vulcanized with the uncured rubber composition.

According to a second aspect of the present invention, the adhesion rate of the first processing solution is 8% or less, and the latex of resorcin-formalin-rubber latex of the second processing solution is vinylpyridine latex. A method for bonding an ethylene / α-olefin rubber composition and a fiber cord according to item 1.

BEST MODE FOR CARRYING OUT THE INVENTION Ethylene α-
A typical example of the olefin rubber composition is a rubber composed of an ethylene-propylene-diene monomer (EPDM). Here, examples of the diene monomer include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, and cyclooctadiene. In addition, ethylene-propylene rubber (EP
R) can also be used.

For vulcanization of the rubber, sulfur or an organic peroxide is used. As the organic peroxide, for example, 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-butylperoxy) hexane and the like can be mentioned. This organic peroxide is used alone or as a mixture, usually in an amount of 0.005 to 0.02 per 100 g of the ethylene-α-olefin elastomer.
It is used in the range of mol g.

Also, by blending a crosslinking aid,
By increasing the degree of crosslinking, problems such as adhesive wear can be prevented. Examples of the crosslinking aid include TIA
Normal peroxides such as C, TAC, 1,2 polybutadiene, metal salts of unsaturated carboxylic acids, oximes, guanidine, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, NN'-m-phenylenebismaleimide, and sulfur It is used for sulfuric acid.

If necessary, ordinary rubbers such as carbon black, reinforcing agents such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids and coloring agents. What is used in the formulation is used.

The fiber cord used in the present invention is a cord made of fibers such as aramid fiber, polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, and polyparaphenylene benzobisoxazole (PBO) fiber. .

[0014] The twisted cord used is treated by the following method. (1) First, the untreated twisted cord is immersed in a first treatment liquid set at room temperature with an isocyanate compound or / and an epoxy resin for 0.5 to 30 seconds, and then placed in an oven adjusted to 150 to 190 ° C. for 2 to 5 seconds. Allow to dry for minutes.

As the isocyanate compound used in the first treatment liquid, for example, 4,4'-diphenylmethane diisocyanate, tolylene 2,4-diisocyanate,
Examples include polymethylene polyphenyl diisocyanate, hexamethylene diisocyanate, and polyaryl polyisocyanate (for example, PAPI is a trade name).
This isocyanate compound is also used by being mixed with an organic solvent such as toluene and methyl ethyl ketone.

A blocked polyisocyanate obtained by reacting the above isocyanate compound with a blocking agent such as phenols, tertiary alcohols and secondary alcohols to block the isocyanate group of the polyisocyanate can also be used. .

Examples of the epoxy compound used in the first treatment liquid include polyhydric alcohols such as ethylene glycol, glycerin and pentaerythritol, and reaction of a polyalkylene glycol such as polyethylene glycol with a halogen-containing epoxy compound such as epichlorohydrin. And a reaction product with a polyhydric phenol such as resorcin, bis (4-hydroxyphenyl) dimethylmethane, a phenol-formaldehyde resin, a resorcin-formaldehyde resin, or a halogen-containing epoxy compound. The epoxy compound is used by being mixed with an organic solvent such as toluene and methyl ethyl ketone.

Here, it is preferable that the adhesion rate of the isocyanate compound or the epoxy compound to the twist cord is 8% or less. If the adhesion rate exceeds 8%, the rigidity of the processing cord increases, and the cord is liable to fly out due to the bending of the belt. The adhesion rate of the isocyanate compound or the epoxy compound to the twisted cord is calculated from the ratio of the mass of the cord before and after the treatment with the first treatment liquid.

(2) Subsequently, a treatment is performed with a second treatment liquid which is an RFL liquid. The RFL solution is obtained by mixing an initial condensate of resorcinol and formalin with rubber latex. In this case, the molar ratio of resorcinol to formalin is preferably 3/1 to 1/3 in order to enhance the adhesive strength. Here, the rubber latex is preferably a vinylpyridine latex in order to improve the adhesive strength of the cord to the ethylene / α-olefin rubber composition.

The precondensate of resorcinol and formalin is
After mixing such that the resin component is 5 to 100 parts by mass with respect to 100 parts by mass of the rubber component of the rubber latex,
The total solids concentration is adjusted to be 5-40%.

The code processed with the first processing solution is the RF
L for 0.5-30 seconds, followed by 200-25
It is heat-treated by passing it through an oven adjusted to 0 ° C for 1 to 3 minutes.

(3) The third treatment liquid is obtained by dissolving a halogenated polymer, an adhesive rubber other than the halogenated polymer, and a vulcanizing agent in a solvent such as toluene and methyl ethyl ketone. Chlorinated rubber, chloroprene rubber, and chlorosulfonated polyethylene rubber. The bonding rubber is a rubber other than the halogenated polymer, and specifically, the above-mentioned ethylene / α-olefin rubber, NBR, SBR, and the like. And ethylene / α-olefin rubbers such as EPDM and EPT. The concentration of the third treatment liquid is preferably 10% by mass or less for the polymer component.

As the vulcanizing agent, dibenzothiazyl disulfide (MBTS), tetramethylthiuram disulfide (TMTD), N-cyclohexyl-2-benzothiazylsulfenamide (CBS), tetramethylthiuram monosulfide (TMTM) ), Mercaptobenzothiazole (MBT), PZ (ZnMDC), sulfur and the like. The vulcanizing agent improves the adhesive strength by heating and pressing the treated fiber cord and the ethylene / α-olefin rubber composition at 140 to 180 ° C.

In the case where an adhesive rubber other than the halogenated polymer is added to the third treatment liquid, the compounding ratio of the halogenated polymer to the adhesive rubber is 3: 7 to 7: 3. Within this range, the adhesive strength is further improved. Also,
Adhesion rate of solid adhesive to fiber cord after bonding is 3 ~
By setting the content to 16% by weight, the adhesion of scum to the cord is suppressed, the appearance of the cord is improved, and the cause of the cord running over the cord during cord spinning and the cord opening is eliminated.

The twisted cord having been subjected to the above-mentioned bonding treatment is used, for example, as a core wire of a V-ribbed belt shown in FIG. The V-ribbed belt 1 has a core 2 made of a high-strength, low-elongation twisted cord embedded in an adhesive rubber layer 3 and a compression rubber layer 4 below the core. 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, and a rubber attached canvas 5 is provided on the surface of the belt.

The rubber used for the compressed rubber layer 4 is such that short fibers such as aramid, nylon, polyester, vinylon, and cotton are 1 to 50 parts by mass, preferably 5 to 100 parts by mass of the ethylene-α-olefin elastomer. To 25 parts by mass.

On the other hand, the adhesive rubber layer 3 has heat resistance,
In order to improve the adhesion with the core wire, the ethylene-α-
An olefin elastomer rubber composition that can be vulcanized with sulfur is used. In addition, if necessary, carbon black, fillers such as silica, fillers such as calcium carbonate and talc, plasticizers, stabilizers, processing aids, coloring agents, etc. used for normal rubber compounding are used. Is done.

The amount of sulfur added to the adhesive rubber layer 3 is 0.5 to 3.0 parts by mass based on 100 parts by mass of the ethylene-α-olefin elastomer.

In the ethylene-α-olefin elastomer used for the adhesive rubber layer 3, EPDM is
It is desirable that the iodine value is 4 or more and less than 40. If the iodine value is less than 4, vulcanization of the rubber composition with sulfur is not sufficient, and a problem of ejection of the core wire occurs. Meanwhile, 4
If it exceeds 0, the scorch of the rubber composition becomes short and handling becomes difficult, and heat resistance deteriorates.

An example of a method for manufacturing a V-ribbed belt is as follows. First, one or a plurality of cover canvases and a rubber sheet forming an adhesive rubber layer are wrapped around the peripheral surface of a cylindrical forming drum, and then a cord made of a rope is helically wrapped thereon, and further compressed rubber is formed. After winding the layer to obtain a laminate, the laminate is vulcanized in a vulcanizer to obtain a vulcanized sleeve.

Next, the vulcanization sleeve is hung on a drive roll and a driven roll, and is run under a predetermined tension, and the rotated grinding wheel is brought into contact with the running vulcanization sleeve to compress the vulcanization sleeve. A plurality of 3 to 100 grooves are formed on the surface of the rubber layer at a time.

The obtained vulcanization sleeve is detached from the driving roll and the driven roll, and the vulcanization sleeve is hung on another driving roll and the driven roll to travel, cut to a predetermined width by a cutter, and cut into individual V-shapes. Finish with ribbed belt.

Another example of the use of the fiber cord of the present invention is a V-belt. The V-belt 21 shown in FIG. 2 has a cord 23 embedded in an adhesive rubber layer 24, and has a compressed rubber layer 26 as an elastic layer below the core wire 23. Cogs may be provided on the compressed rubber layer 26 at predetermined intervals along the longitudinal direction.

[0034]

The present invention will be described in more detail with reference to the following examples. Example 1 A 1,100 dtex / 1 × 5 PEN twisted cord was immersed in the first treatment liquid (PD-1) shown in Table 1, and then dipped in 180.
Heat treated at 4 ° C. for 4 minutes.

[0035]

[Table 1]

Next, the RFL solution shown in Table 2 (RFL-
After immersion in A), heat treatment was performed at 230 ° C. for 2 minutes.

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

The treatment cords arranged in a width of 25 mm without gap and the EPDM adhesive rubber having the composition shown in Table 3 were vulcanized in close contact, and the flat peeling force between them was measured at room temperature and in an atmosphere at 120 ° C.
The adhesive strength between the treated cord and the adhesive rubber was evaluated. Table 5 shows the results.

Examples 2 to 4 PET treatment codes were prepared using the first treatment liquids (PD-1 to PD-3) shown in Table 1, and the flat peeling force was measured in the same manner as in Example 1, And use the above processing code for 3PK
A V-ribbed belt having a size of 1100 was produced. The obtained V-ribbed belt was set in a running test machine including a driving pulley having a diameter of 120 mm, a driven pulley, and a tension pulley having a diameter of 45 mm. The driving pulley was driven at 4,900 rpm while applying a load of 8.8 kW to the driven pulley and a load of 834 N to the tension pulley. 500
After running for a time, the peeling force of two arbitrary core wires was measured and compared with the peeling force of two core wires of the V-ribbed belt before running manufactured under the same conditions. The results are also shown in Table 5.

Comparative Example 1 A processing code of PEN was prepared under the same conditions as in Example 1 except that the RFL liquid of the second processing liquid in Example 1 was changed to RFL-B. The peel force was measured. The results are also shown in Table 5.

Comparative Examples 2 and 3 The combination of the first processing solution and the second processing solution was used as PD-4, respectively.
And P as RFL-A solution, PD-1 and RFL-B solution
An ET processing code was prepared, and the flat peeling force was measured in the same manner as in Comparative Example 1. In addition, Example 2 was prepared using the above processing code.
A V-ribbed belt having a size of 3PK1100 was produced in the same manner as in Nos. 1 to 4. A running test was performed in the same manner, and the peeling force of the two core wires was measured. The results are also shown in Table 5.

[0044]

[Table 5]

In Example 1 in which the adhesion rate of the first treatment liquid was 8% or less and the RFL liquid composed of vinylpyridine latex was used as the second treatment liquid, excellent flat peeling force was obtained at both room temperature and 120 ° C. Obtained. In contrast, N
In Comparative Example 1 in which the RFL solution composed of BR latex was used as the second treatment liquid, a decrease in the flat peeling force was observed particularly at 120 ° C.

In Examples 2 to 4 in which the cord of the first treatment liquid was 8% or less and the cord was a cord in which the RFL liquid composed of vinyl pyridine latex was used as the second treatment liquid, 500 hours was used. After running, the peeling force is 70 before running.
%, And good adhesive strength was observed. on the other hand,
In Comparative Example 2 in which the cord was a treatment code having an adhesion rate of the first treatment liquid of more than 8%, ejection of the cord was observed without completing the prescribed running time. Further, in Comparative Example 3 in which the processing cord using the RFL liquid composed of NBR latex as the second processing liquid and the core cord was used, remarkable deterioration of the peeling force was observed after running for 500 hours.

[0047]

As described above, according to the present invention, the fiber cord is treated with the first treatment liquid comprising an isocyanate compound and / or an epoxy compound, and then the second treatment with resorcin-formalin-rubber latex. Liquid, followed by a third processing liquid obtained by adding a vulcanizing agent to a halogenated polymer, and then vulcanized tightly with an unvulcanized rubber composition of ethylene / α-olefin rubber. A method for bonding an ethylene / α-olefin rubber composition to a fiber cord, comprising: an ethylene / α-olefin rubber composition such as EPDM rubber; and a treated cord comprising PET fiber, PEN fiber, PBO fiber and the like. Adhesive strength is obtained. Then, using the processing code as a core wire, EPD
If an ethylene / α-olefin rubber composition such as M rubber is used for the adhesive rubber layer, it is possible to provide a power transmission belt characterized by excellent adhesive strength having sufficient residual adhesive strength even after the belt runs.

[Brief description of the drawings]

FIG. 1 is a sectional view of a V-ribbed belt.

FIG. 2 is a sectional view of a V-belt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 V-ribbed belt 2 core wire 3 Adhesive rubber layer 4 Compressed rubber layer 5 Reinforcement cloth 7 Rib 21 V belt 22 Reinforcement cloth 23 Core wire 24 Adhesive rubber layer 26 Compressed rubber layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J040 CA021 CA151 DA021 DA191 DH041 EB061 GA03 HA046 HD03 HD05 HD10 JA03 JB02 KA16 LA06 MA10 MA12 MB02 MB05 PA12 PA13 PA18 PA26

Claims (2)

[Claims] 1. A method for bonding an ethylene / α-olefin rubber composition and a fiber cord, wherein the fiber cord is treated with a first treatment liquid comprising an isocyanate compound and / or an epoxy compound, and then a resorcinol-formalin-rubber latex is prepared. After the treatment with the second treatment liquid, and further after the treatment with the third treatment liquid in which a vulcanizing agent is added to the halogenated polymer, the mixture was tightly vulcanized with the unvulcanized rubber composition of ethylene / α-olefin rubber. Ethylene-α-
A method for bonding an olefin rubber composition to a fiber cord. 2. The ethylene / α- according to claim 1, wherein the adhesion rate of the first treatment liquid is 8% or less, and the latex of resorcin-formalin-rubber latex of the second treatment liquid is vinylpyridine latex. A method for bonding an olefin rubber composition to a fiber cord.