JP5855931B2 - Rubber composition for conveyor belt and conveyor belt - Google Patents

Description

  The present invention relates to a rubber composition for a conveyor belt and a conveyor belt, and more particularly to a rubber composition for a conveyor belt, which is excellent in processing stability and has a good heat resistance.

  In recent years, conveyor belts have been used as means for transporting articles in various industrial fields. In order to give durability to such a conveyor belt, generally, a reinforcing member such as a canvas made of a metal member such as a steel cord or an aramid fiber is used as a core material, and this is laminated so as to cover a cover rubber. Manufactured by vulcanization. Cover rubber has high tear resistance, high tensile strength, suitable elongation, moderate flexibility and elasticity, high flexibility, good wear resistance, good aging resistance, high impact resistance The property of being good is required, and further, the property corresponding to the intended use is required. For example, excellent heat resistance is required for a cover rubber constituting a conveyor belt for conveying a high-temperature material such as coke in an iron mill or a sintered product in a cement factory. These cover rubbers have a problem that the contact portion with the object to be conveyed is damaged by heat, and the performance is locally lowered.

  In order to prevent such deterioration of the performance of the conveyor belt due to heat, a rubber composition for conveyor belts excellent in heat resistance has been developed. For example, in Patent Document 1, a rubber mixture containing at least one of natural rubber, styrene-butadiene copolymer rubber (SBR), and butadiene rubber is added to a specific amount of an organic acid cobalt salt or organic acid nickel salt, sulfur, thiuram-based. A rubber composition containing a vulcanization accelerator and the like is described. Certainly, by combining a thiuram vulcanization accelerator with sulfur, it is possible to achieve high heat resistance of the conveyor belt, but the Mooney scorch time is shortened and there is a possibility that rubber scoring may occur during production. In order to prevent this rubber burn, generally, a technique of blending a sulfenamide vulcanization retarder such as CTP (N-cyclohexylthiophthalimide) as a vulcanization retarder is used. By adding CTP, a vulcanization delay effect is surely obtained, and the processability of the rubber composition is stabilized, but the heat resistance of a conveyor belt manufactured using the rubber composition is lowered. there were. Thus, since heat resistance and processing stability are in a trade-off relationship, it has been difficult to achieve both.

Japanese Patent Laid-Open No. 11-302457

  An object of this invention is to provide the rubber composition for conveyor belts which has the outstanding process stability and can improve the heat resistance of a conveyor belt.

  As a result of diligent studies to achieve the above object, the present inventor has found that a rubber composition obtained by blending sulfur, a vulcanization accelerator, and N-phenyl-N- (trichloromethylthio) benzenesulfonamide with a diene polymer. It has been found that the product has excellent processing stability and that the heat resistance of the conveyor belt can be greatly improved by using the rubber composition, and the present invention has been completed.

That is, the conveyor belts for the rubber composition of the present invention, diene polymer, sulfur, vulcanization accelerator, containing N- phenyl -N- (trichloromethyl thio) benzenesulfonamide, the vulcanization accelerator, tetra It includes two or more selected from the group consisting of benzyl thiuram disulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, and tetrabutyl thiuram disulfide .

With this configuration, it is possible to achieve both excellent processing stability of the rubber composition for conveyor belts and high heat resistance of a conveyor belt manufactured using the rubber composition.
In the rubber composition for a conveyor belt according to the present invention, the vulcanization accelerator preferably contains both tetramethylthiuram disulfide and tetrabutylthiuram disulfide. If tetramethylthiuram disulfide and tetrabutylthiuram disulfide are used in combination, the balance between the vulcanization rate and the characteristics after heat aging will be good.

  In the rubber composition for conveyor belts of the present invention, the amount of the N-phenyl-N- (trichloromethylthio) benzenesulfonamide is 0.5 to 4.0 parts by mass with respect to 100 parts by mass of the diene polymer. It is preferable that By containing the N-phenyl-N- (trichloromethylthio) benzenesulfonamide in the above amount, the processing stability of the rubber composition for conveyor belts and the heat resistance of the conveyor belt manufactured using the rubber composition Can be achieved at a higher level.

  Moreover, the conveyor belt of this invention is manufactured using the said rubber composition for conveyor belts, It is characterized by the above-mentioned.

  Thus, if a conveyor belt is manufactured using the rubber composition for conveyor belts described above, since the rubber composition is excellent in processing stability, a conveyor belt having a shape according to the application can be formed. Moreover, the conveyor belt has high heat resistance.

  According to the present invention, it is possible to provide a rubber composition for a conveyor belt, which has excellent processing stability and can greatly improve the heat resistance of a conveyor belt manufactured using the rubber composition. Can do.

  Hereinafter, the present invention will be specifically described. The rubber composition for conveyor belts of the present invention is characterized by containing a diene polymer, sulfur, a vulcanization accelerator, and N-phenyl-N- (trichloromethylthio) benzenesulfonamide.

<Diene polymer>
The rubber component of the rubber composition of the present invention contains a diene polymer. Diene polymers include styrene-butadiene rubber (SBR), butadiene rubber (BR), natural rubber (NR), isoprene rubber (IR), chloroprene rubber (CR), ethylene-propylene-diene rubber (EPDM), butyl rubber ( IIR), halogenated butyl rubber, or a mixture thereof. Among these, styrene-butadiene rubber is preferable from the viewpoint of improving heat resistance. As the styrene-butadiene rubber, emulsion polymerization SBR (E-SBR), solution polymerization SBR (S-SBR) and the like can be used.

  Further, the rubber component of the present invention may further contain other rubber. Examples of other rubbers include ethylene-propylene rubber (EPR), urethane rubber (U), silicone rubber (Q), acrylic rubber (ACM), and mixtures thereof.

<Sulfur>
The conveyor belt of the present invention contains sulfur. The compounding amount of sulfur is preferably 0.1 to 1 part by mass and more preferably 0.1 to 0.5 part by mass with respect to 100 parts by mass of the diene polymer. When the blending amount of sulfur is 0.1 parts by mass or more with respect to the diene polymer, crosslinking is sufficient, and when it is 0.5 parts by mass or less, sufficient durability is obtained.

<Vulcanization accelerator>
Examples of vulcanization accelerators include benzothiazoles such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, and Nt-butyl-2-benzothiazylsulfenamide. Vulcanization accelerators, guanidine vulcanization accelerators such as diphenylguanidine, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetradodecylthiuram disulfide, tetraoctylthiuram disulfide, tetrabenzylthiuram disulfide, dipentamethylenethiuramtetrasulfide Examples include thiuram vulcanization accelerators such as sulfides, dithiocarbamate salts such as zinc dimethyldithiocarbamate, and other zinc dialkyldithiophosphates. These vulcanization accelerators may be used individually by 1 type, and may be used in mixture of 2 or more types. Among these, as the vulcanization accelerator, a thiuram vulcanization accelerator is preferable from the viewpoint of heat resistance, and tetramethylthiuram disulfide and tetrabutylthiuram disulfide are more preferable because they have good property retention after heat aging. Tetramethylthiuram disulfide and tetrabutylthiuram disulfide are most preferably used in combination because of a good balance between the vulcanization rate and the characteristics after heat aging.

  The blending amount of the vulcanization accelerator is preferably 1 to 7 parts by mass and more preferably 1.5 to 5 parts by mass with respect to 100 parts by mass of the diene polymer. When the blending amount of the vulcanization accelerator is 7 parts by mass or less with respect to 100 parts by mass of the diene polymer, the extensibility is good (sufficient elongation is obtained), and when it is 1 part by mass or more, hardness, strength, etc. The physical properties of the are improved.

<N-phenyl-N- (trichloromethylthio) benzenesulfonamide>
The rubber composition for conveyor belts of the present invention contains N-phenyl-N- (trichloromethylthio) benzenesulfonamide. By including N-phenyl-N- (trichloromethylthio) benzenesulfonamide, the processing stability of the rubber composition is the same as the conventional method of blending a vulcanization retarder such as CTP (N-cyclohexylthiophthalimide). Can be improved. In addition, unlike the conventional vulcanization retarder, there is no significant adverse effect on the heat resistance of the conveyor belt produced using the rubber composition.

  The blending amount of N-phenyl-N- (trichloromethylthio) benzenesulfonamide is preferably 0.5 to 4 parts by mass, more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the diene polymer. is there. By blending N-phenyl-N- (trichloromethylthio) benzenesulfonamide in such an amount, the processing stability of the rubber composition for conveyor belts and the rubber composition for conveyor bells produced using the rubber composition The heat resistance can be compatible at a higher level.

In the rubber composition for conveyor belts of the present invention, additives other than the above components may be appropriately blended as necessary. As such an additive, for example, a vulcanization acceleration aid, carbon black, and an antioxidant are preferable. Furthermore, waxes, silica, reinforcing fillers such as silica coupling agent, calcium carbonate, mineral fillers and clay, a plasticizer, a softening agent such as aromatic oil, phenolic resins, resins such as C ₅ petroleum resins , Antioxidants, lubricants, ultraviolet absorbers, dispersants, compatibilizing agents, homogenizing agents, etc. can be blended, and vulcanization retarders can be blended as long as the effects of the present invention are not impaired. Good.

  As carbon black, those of SRF, GPF, FEF, HAF, ISAF, SAF, FT, and MT grades are preferred, and those of HAF and ISAF grades are most preferred. These carbon blacks may be used alone or in a combination of two or more. The compounding amount of the carbon black is preferably 30 to 70 parts by mass, more preferably 40 to 60 parts by mass with respect to 100 parts by mass of the diene polymer. When the blending amount of the carbon black is 30 parts by mass or more with respect to the diene polymer, sufficient reinforcement is obtained, and when it is 70 parts by mass or less, the processing stability is also good.

  Examples of the anti-aging agent include radical chain inhibitors such as amine-based anti-aging agents and phenol-based anti-aging agents, and peroxide decomposition agents such as benzimidazole-based compounds. In particular, a benzimidazole compound is preferable because of excellent aging characteristics. These antioxidants may be used alone or in combination of two or more. The blending amount of the antioxidant is preferably 2 to 10 parts by mass, more preferably 3 to 8 parts by mass with respect to 100 parts by mass of the diene polymer. When the blending amount of the antioxidant is 10 parts by mass or less with respect to 100 parts by mass of the diene polymer, the balance between aging characteristics and physical properties is good, and when it is 2 parts by mass or more, sufficient aging characteristics are obtained.

  The rubber composition for conveyor belts of the present invention can be produced by kneading these components with, for example, a Banbury mixer, a kneader or the like.

  The conveyor belt of the present invention can be produced by bringing the rubber composition for conveyor belt into close contact with a reinforcing material and vulcanizing it. For example, a sheet-like cover rubber layer is manufactured by extruding the rubber composition for conveyors, and a reinforcing material is sandwiched from above and below by the cover rubber layer, and this belt molded product is set in a mold and set at a predetermined temperature. And vulcanize at a pressure for a predetermined time. Since the high temperature conveyed object comes into contact with the upper cover rubber layer, if the rubber composition of the present invention is used only for the upper cover rubber layer, it is sufficient to improve the heat resistance of the conveyor belt of the present invention. Of course, the rubber composition of the present invention may be used only for the lower cover layer.

  The reinforcing material can be appropriately selected from those normally used for a conveyor belt in consideration of the size and the like according to the use of the conveyor belt. Specific examples include galvanized steel cords, brass-plated steel cords, or aramid canvas using aramid fibers. According to the present invention, a conveyor belt having sufficiently excellent heat resistance can be obtained using any of them. be able to.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

[Examples 1-4, Comparative Examples 1-3]
A rubber composition having the composition shown in Table 1 was prepared according to a conventional method. The obtained unvulcanized rubber composition was appropriately vulcanized and molded to prepare a test piece having a length of 120 mm, a width of 120 mm, and a thickness of 2 mm. Using this test piece, hardness and heat resistance were evaluated by the following evaluation methods. The processing stability of the rubber composition was evaluated by measuring Mooney scorch time. The evaluation results are shown in Table 1.

"Evaluation method"
・ Hardness (Hd)
It measured based on JIS K 6253 (type A). It shows that it is excellent in hardness, so that a value is large.

・ Heat resistance (retention rate)
A thermal aging treatment was performed at 120 ° C. for 96 hours, and the tensile elongation (Eb), tensile strength (Tb), and tensile stress (Md300) before and after the treatment were measured, and the retention after the treatment was calculated and evaluated. It shows that it is excellent in heat resistance, so that a retention rate is high. About tensile elongation and tensile strength, it measured based on JISK6251. Regarding the tensile stress, the stress (Md300) when the elongation was 300% was measured in accordance with JIS K6251.

・ Processing stability (Mooney coach time)
It was based on JIS K 6300-1: 2001 (how to determine viscosity and scorch time using Mooney viscometer). The Mooney scorch time was measured by measuring the rubber composition at 130 ° C., and measuring the time (minutes) from the start of preheating until the value rose 5 units from the minimum value Vm. The longer the Mooney scorch time, the better the processing stability (scorch stability).

* 1 JSR, SBR1500
* 2 Show Black N330, manufactured by Cabot Japan
* 3 New Nippon Rika Co., Ltd., stearic acid 50S
* 4 Suntite S, manufactured by Seiko Chemical Co., Ltd.
* 5 Nouchi 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Industry
* 6 Nouchi NS-6 (N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry
* 7 Nouchi MB (2-mercaptobenzimidazole) manufactured by Ouchi Shinsei Chemical Industry
* 8 Hitachi Chemical, Hitator 1502P
* 9 Made by Exxon, Escorez 1102
* 10 Idemitsu Kosan, Dianaprolos Oil AH-58
* 11 Tsurumi Chemical Industries, ordinary sulfur * 12 Ouchi Shinsei Chemical Industries, Noxeller TT-P (tetramethylthiuram disulfide)
* 13 Nouchira TBT (tetrabutylthiuram disulfide), manufactured by Ouchi Shinsei Chemical Industry
* 14 Made by Hakusuitec Co., Ltd., No. 3, zinc white * 15 Made by LANXESS, Bull Current E / C
* 16 Made by Monsanto, Santo Guard PVI (N-cyclohexylthiophthalimide)

As is apparent from the results in Table 1, Examples 1 to 4 containing a diene polymer, sulfur, a vulcanization accelerator, and N-phenyl-N- (trichloromethylthio) benzenesulfonamide are compared with the comparative examples. Thus, good processing stability (Mooney scorch time) and heat resistance (retention rate) are balanced, and the effects of the present invention have been confirmed.

  On the other hand, since Comparative Example 1 did not contain N-phenyl-N- (trichloromethylthio) benzenesulfonamide, the Mooney scorch time was short and the processing stability was poor. Since Comparative Examples 2 and 3 did not contain N-phenyl-N- (trichloromethylthio) benzenesulfonamide and contained a vulcanization retarder, the hardness and the tensile elongation retention ratio were remarkably inferior. . Comparative Examples 2 and 3 were also inferior in hardness, tensile strength, and tensile stress before heat aging treatment.

Claims (4)

A diene polymer, sulfur, a vulcanization accelerator, N-phenyl-N- (trichloromethylthio) benzenesulfonamide , and the vulcanization accelerator is tetrabenzyl thiuram disulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, And a rubber composition for conveyor belts , comprising two or more selected from the group consisting of tetrabutylthiuram disulfide . The rubber composition for a conveyor belt according to claim 1, wherein the vulcanization accelerator contains both tetramethylthiuram disulfide and tetrabutylthiuram disulfide. The N- phenyl -N- amount of (trichloromethyl thio) benzenesulfonamide is claim 1 or, wherein the a 0.5 to 4.0 parts by mass with respect to diene polymer 100 parts by weight 2. The rubber composition for conveyor belts according to 2. A conveyor belt produced using the rubber composition for a conveyor belt according to any one of claims 1 to 3 .