阅读说明：本技术 钢帘线粘接用橡胶组合物以及传送带 (Rubber composition for bonding steel cord and conveyor belt ) 是由 邹德庆 米田优子 铃木邦俊 于 2020-02-19 设计创作，主要内容包括：本发明提供一种耐寒性、耐久性以及耐水粘接性优异的钢帘线粘接用橡胶组合物以及传送带。一种钢帘线粘接用橡胶组合物以及使用上述钢帘线粘接用橡胶组合物而形成的传送带,所述钢帘线粘接用橡胶组合物含有至少包含聚丁二烯橡胶的橡胶成分和新癸酸硼酸钴。(The invention provides a rubber composition for bonding a steel cord, which has excellent cold resistance, durability and water-resistant bonding property, and a conveyor belt. A rubber composition for bonding a steel cord, which contains a rubber component containing at least polybutadiene rubber and cobalt neodecanoate borate, and a conveyor belt formed by using the rubber composition for bonding a steel cord.)

1. A rubber composition for bonding a steel cord, which contains a rubber component containing at least polybutadiene rubber and cobalt neodecanoate borate.

2. The rubber composition for bonding steel cords according to claim 1,

the rubber component further comprises natural rubber and/or styrene butadiene copolymer rubber.

3. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

the polybutadiene rubber is contained in an amount of 15 to 60 parts by mass per 100 parts by mass of the rubber component.

4. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

also contains carbon black, and the additive also contains carbon black,

the content of the carbon black is 35 to 75 parts by mass per 100 parts by mass of the rubber component.

5. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

the content of the cobalt borate neodecanoate is 1.2 to 3.5 parts by mass per 100 parts by mass of the rubber component.

6. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

and also contains a vulcanization accelerator, and the like,

the vulcanization accelerator is a thiazole vulcanization accelerator.

7. The rubber composition for bonding steel cords according to claim 6,

the content of the vulcanization accelerator is 0.3 to 1.2 parts by mass with respect to 100 parts by mass of the rubber component.

8. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

also contains sulfur, and the additive also contains sulfur,

the sulfur content is 2.1 to 5.0 parts by mass per 100 parts by mass of the rubber component.

9. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

further comprises at least one selected from the group consisting of rosin, rosin derivatives, phenol resins, and chlorinated paraffins.

10. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

and also contains zinc oxide, and the zinc oxide,

the content of the zinc oxide is 5.0 parts by mass or more per 100 parts by mass of the rubber component.

11. The rubber composition for steel cord adhesion according to claim 1 or 2, wherein,

also contains the oil, and the oil is mixed,

the oil content is 2.0 parts by mass or more per 100 parts by mass of the rubber component.

12. The rubber composition for steel cord adhesion according to claim 1 or 2, which is used for adhesion of a galvanized steel cord.

13. A conveyor belt comprising the rubber composition for bonding steel cords according to any one of claims 1 to 12.

Technical Field

The present invention relates to a rubber composition for bonding a steel cord and a conveyor belt.

Background

Conventionally, various rubber compositions have been proposed for the purpose of improving adhesion performance to a steel cord.

For example, patent document 1 proposes a rubber composition in which 40 to 80 parts by mass of carbon black, cobalt neodecanoate borate, a phenolic resin, and a curing agent are added to 100 parts by mass of a diene rubber containing a natural rubber, wherein the carbon black has a DBP oil absorption of 50 × 10^-5～80×10^-5m³The iodine adsorption amount is 100 to 150g/kg, the dynamic storage modulus (E') at 20 ℃ under a dynamic strain of 2% is 8MPa or more, the loss tangent (tan) at 60 ℃ is 0.20 or less, and the number of repetitions until failure in a constant strain fatigue test at 400rpm under a strain of 60% is 45000 or more.

Further, patent document 2 discloses a method for bonding a galvanized steel cord to a rubber, which comprises bonding a rubber composition to a galvanized steel cord, the rubber composition containing, per 100 parts by weight of a sulfur-vulcanizable rubber: 3 to 15 parts by weight of rosin or rosin derivatives, 0.2 to 1.0 part by weight of organic cobalt salt based on the amount of cobalt, and 3 to 50 parts by weight of organic chlorine compounds.

Disclosure of Invention

Problems to be solved by the invention

On the other hand, when a conveyor belt incorporating a steel cord is used in cold regions, the rubber composition used for the coating rubber layer (cushion rubber) coating the steel cord is required to have cold resistance in addition to adhesion to the steel cord in the conveyor belt.

Under such a background, the present inventors have made reference to patent document 1 and the like to prepare a rubber composition and have evaluated it, and as a result, it is obvious that: such a composition has poor cold resistance and is difficult to achieve both durability and water-resistant adhesion (comparative examples 2 to 4).

Accordingly, an object of the present invention is to provide a rubber composition for bonding a steel cord, which is excellent in cold resistance, durability and water-resistant adhesion. In the present invention, the water-resistant adhesion includes moisture-resistant adhesion.

Another object of the present invention is to provide a conveyor belt having excellent cold resistance, durability, and water-resistant adhesion.

Technical scheme

The present inventors have conducted extensive studies to solve the above-mentioned problems, and as a result, have found that the desired effects can be obtained when a rubber composition contains a rubber component containing at least a polybutadiene rubber and cobalt neodecanoate borate.

The present invention has been made based on the above-described findings, and specifically, the above-described problems are solved by the following configurations.

[1] A rubber composition for bonding a steel cord, which contains a rubber component containing at least polybutadiene rubber and cobalt neodecanoate borate.

[2] The rubber composition for bonding a steel cord according to [1], wherein the rubber component further comprises a natural rubber and/or a styrene butadiene copolymer rubber.

[3] The rubber composition for bonding a steel cord according to [1] or [2], wherein the polybutadiene rubber is contained in an amount of 15 to 60 parts by mass per 100 parts by mass of the rubber component.

[4] The rubber composition for bonding a steel cord according to any one of [1] to [3], further comprising carbon black, wherein the content of the carbon black is 35 to 75 parts by mass with respect to 100 parts by mass of the rubber component.

[5] The rubber composition for bonding a steel cord according to any one of [1] to [4], wherein the content of the cobalt neodecanoate borate is 1.2 to 3.5 parts by mass per 100 parts by mass of the rubber component.

[6] The rubber composition for bonding a steel cord according to any one of [1] to [5], further comprising a vulcanization accelerator, wherein the vulcanization accelerator is a thiazole-based vulcanization accelerator.

[7] The rubber composition for bonding a steel cord according to [6], wherein the vulcanization accelerator is contained in an amount of 0.3 to 1.2 parts by mass per 100 parts by mass of the rubber component.

[8] The rubber composition for bonding a steel cord according to any one of [1] to [7], further comprising sulfur in an amount of 2.1 to 5.0 parts by mass per 100 parts by mass of the rubber component.

[9] The rubber composition for bonding a steel cord according to any one of [1] to [8], further comprising at least one selected from the group consisting of rosin, rosin derivatives, phenol resins, and chlorinated paraffins.

[10] The rubber composition for bonding a steel cord according to any one of [1] to [9], further comprising zinc oxide, wherein the content of zinc oxide is 5.0 parts by mass or more per 100 parts by mass of the rubber component.

[11] The rubber composition for bonding a steel cord according to any one of [1] to [10], further comprising an oil, wherein the oil is contained in an amount of 2.0 parts by mass or more per 100 parts by mass of the rubber component.

[12] The rubber composition for bonding a steel cord according to any one of [1] to [11], which is used for bonding a galvanized steel cord.

[13] A conveyor belt formed by using the rubber composition for bonding steel cords according to any one of [1] to [12 ].

Advantageous effects

The rubber composition for bonding a steel cord of the present invention is excellent in cold resistance, durability and water-resistant adhesion.

The conveyor belt of the present invention is excellent in cold resistance, durability, and water-resistant adhesion.

Drawings

FIG. 1 is a cross-sectional perspective view schematically illustrating one example of the conveyor belt of the present invention.

Detailed Description

The present invention will be described in detail below.

The numerical range expressed by the term "to" in the present specification means a range including numerical values described before and after the term "to" as a lower limit value and an upper limit value.

In the present specification, unless otherwise specified, each component may be used alone or in combination of two or more kinds thereof. When the component contains two or more substances, the content of the component refers to the total content of the two or more substances.

In the present specification, the method for producing each component is not particularly limited as long as it is not described in advance. For example, a conventionally known method can be cited.

In the present specification, the more excellent at least one of the cold resistance, the durability and the water-resistant adhesion may be referred to as the more excellent effect of the present invention.

[ rubber composition for adhesion of Steel cord ]

The rubber composition for bonding a steel cord of the present invention (the composition of the present invention) is a rubber composition for bonding a steel cord containing a rubber component containing at least polybutadiene rubber and cobalt borate neodecanoate.

It can be considered that: the composition of the present invention has such a constitution, and therefore, a desired effect can be obtained. Although the reason for this is not clear, it is estimated that the reason is as follows.

The composition of the present invention contains polybutadiene rubber as a rubber component, and thus can set the embrittlement temperature to a preferable range and is excellent in cold resistance.

Further, the present inventors have found that: when cobalt naphthenate is used as the organic cobalt salt, there is a problem that the retention of elongation at break (EB) of the rubber in an over-vulcanized state is low, and the durability of the conveyor belt is lowered.

Here, the above-mentioned overcuring means that the rubber is further vulcanized after a usual vulcanization time (after initial vulcanization) required for producing a product. Specific examples of the above-mentioned further vulcanization include: a case where the vulcanization time in vulcanizing unvulcanized rubber is longer than usual; the case where the vulcanized rubber or the like is further vulcanized when the vulcanized rubber or the conveyor belt is repaired; a case where the vulcanized rubber is further vulcanized and cyclized; and the like.

With respect to the above problems, the present inventors have found that: in the case of using cobalt neodecanoate borate as the organic cobalt salt, the water resistant adhesion can be maintained or improved, and the durability of the conveyor belt can be improved.

The present inventors speculate that: when the amount of cobalt contained in the cobalt neodecanoate borate or the cobalt naphthenate is equal, the cobalt neodecanoate borate contains less organic acid than the cobalt naphthenate, and therefore, the reduction in elongation at break (EB) after overcuring can be reduced.

As described above, the composition of the present invention contains cobalt neodecanoate borate, and thus can achieve both durability and water-resistant adhesion at an excellent level.

As described above, the composition of the present invention is excellent in cold resistance, durability and water-resistant adhesion.

Hereinafter, each component contained in the composition of the present invention will be described in detail.

< rubber component >

The composition of the present invention contains a rubber component containing at least polybutadiene rubber.

< polybutadiene rubber >

The polybutadiene rubber (butadiene rubber, also referred to as "BR") contained in the composition of the present invention is not particularly limited as long as it is a homopolymer of butadiene. The polybutadiene rubber may be modified.

(weight average molecular weight of polybutadiene rubber)

From the viewpoint of further improving the effect of the present invention and increasing the drawing force (force required for drawing the steel cord from the rubber), the weight average molecular weight of the polybutadiene rubber is preferably 40 to 100 ten thousand, and more preferably 45 to 80 ten thousand.

In the present invention, the weight average molecular weight of the polybutadiene rubber is a standard polystyrene equivalent value based on a measurement value obtained by Gel Permeation Chromatography (GPC) using cyclohexane as a solvent.

(glass transition temperature of polybutadiene rubber)

From the viewpoint of more excellent effects (particularly, cold resistance) of the present invention, the glass transition temperature of the polybutadiene rubber is preferably-50 ℃ or lower, more preferably-150 to-80 ℃.

In the present invention, the glass transition temperature may be set to the following value: in a method according to JIS K7121: 2012, the curve obtained when the change in the heat flow rate was measured at a temperature rise of 20 ℃/min using a differential thermal analyzer, and the value obtained at the inflection point was read.

From the viewpoint that the effect (particularly cold resistance) of the present invention is more excellent, and that the rubber after initial vulcanization is further crosslinked by overcuring so that the rubber is not excessively hard and the embrittlement temperature can be set to an appropriate range, the content of the polybutadiene rubber is preferably 15 to 60 parts by mass, more preferably 20 to 50 parts by mass, further preferably more than 20 parts by mass and 50 parts by mass or less, and particularly preferably 25 to 45 parts by mass with respect to 100 parts by mass of the rubber component.

(rubber other than BR)

The rubber component may contain other rubbers in addition to BR.

Examples of the rubber other than BR include: diene rubbers such as natural rubber, Isoprene Rubber (IR), aromatic vinyl-conjugated diene copolymer rubber (e.g., styrene butadiene copolymer rubber), acrylonitrile butadiene rubber (NBR), butyl rubber (IIR), halogenated butyl rubber, and Chloroprene Rubber (CR).

From the viewpoint of more excellent effects of the present invention, the rubber component preferably further contains natural rubber and/or styrene butadiene copolymer rubber, and more preferably contains natural rubber and styrene butadiene copolymer rubber.

Natural rubber

The Natural Rubber (NR) is not particularly limited. For example, conventionally known natural rubber can be cited.

Styrene butadiene copolymer rubber

The styrene-butadiene copolymer rubber is not particularly limited as long as it is a copolymer of styrene and butadiene.

(bound styrene amount of styrene butadiene copolymer rubber)

From the viewpoint of further improving the effect (particularly, cold resistance) of the present invention and lowering the glass transition temperature of the styrene-butadiene copolymer rubber described later, the amount of bound styrene in the styrene-butadiene copolymer rubber is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, based on the total amount of the styrene-butadiene copolymer rubber.

(vinyl amount of styrene butadiene copolymer rubber)

From the viewpoint of further improving the effect (particularly, cold resistance) of the present invention and lowering the glass transition temperature of the styrene-butadiene copolymer rubber described later, the vinyl content (1, 2-vinyl bond content) of butadiene in the styrene-butadiene copolymer rubber is preferably 5 to 30% by mass, more preferably 5 to 20% by mass, based on the total amount of butadiene repeating units in the styrene-butadiene copolymer rubber.

In the present invention, the amount of the bound styrene and the amount of the vinyl group in the styrene-butadiene copolymer rubber may be determined by¹H-NMR was measured.

(glass transition temperature of styrene butadiene copolymer rubber)

From the viewpoint of further improving the effect (particularly, cold resistance) of the present invention, the glass transition temperature of the styrene-butadiene copolymer rubber is preferably-50 ℃ or lower.

The lower limit of the glass transition temperature of the styrene-butadiene copolymer rubber may be set to, for example, -100 ℃ or higher.

The method for measuring the glass transition temperature of the styrene-butadiene copolymer rubber is the same as described above.

(weight average molecular weight of styrene butadiene copolymer rubber)

The weight average molecular weight of the styrene butadiene copolymer rubber is not particularly limited. For example, 20 to 300 ten thousand may be used.

In the present invention, the weight average molecular weight of the styrene butadiene copolymer rubber is a standard polystyrene equivalent value based on a measurement value obtained by Gel Permeation Chromatography (GPC) using tetrahydrofuran as a solvent.

In the case where the rubber component contains the natural rubber and the styrene-butadiene copolymer rubber in addition to BR (in combination of three components), the content of the natural rubber is preferably 20 to 42.5 parts by mass, more preferably 25 to 40 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint that the effect of the present invention is more excellent and the embrittlement temperature can be set to an appropriate range.

In the case of using the three components in combination, the content of the styrene-butadiene copolymer rubber is preferably 20 to 42.5 parts by mass, more preferably 25 to 40 parts by mass, per 100 parts by mass of the rubber component, from the viewpoint that the effect of the present invention is more excellent and the embrittlement temperature can be set to an appropriate range.

< cobalt neodecanoate borate >

The cobalt neodecanoate borate contained in the composition of the present invention is a compound represented by the following formula (1).

The composition of the present invention contains cobalt neodecanoate borate, and thus has excellent adhesion to a steel cord.

[ chemical formula 1]

(content of cobalt borate neodecanoate)

From the viewpoint that the effect of the present invention is more excellent, the adhesion to a steel cord is excellent, and the rubber after initial vulcanization is not too hard due to further crosslinking by overcuring, the content of the cobalt neodecanoate borate is preferably 1.2 to 3.5 parts by mass, more preferably more than 1.5 parts by mass and 2.5 parts by mass or less, per 100 parts by mass of the rubber component.

(carbon Black)

The compositions of the present invention may also contain carbon black.

The carbon black is not particularly limited.

Among these, the carbon black is preferably an HAF-grade carbon black or an ISAF-grade carbon black, and more preferably an HAF-grade carbon black, from the viewpoint of further improving the effects of the present invention.

(nitrogen adsorption specific surface area of carbon Black)

From the viewpoint of further improving the effect of the present invention, the nitrogen adsorption specific surface area (N) of the carbon black is₂SA) is preferably 60 to 120m²A concentration of 65 to 95m is more preferable²/g。

The nitrogen adsorption specific surface area of carbon black can be determined in accordance with JIS K6217-2: 2017 "second part: the method for solving the specific surface area, nitrogen adsorption method, single-point method "measures the amount of nitrogen adsorbed on the surface of carbon black.

(content of carbon Black)

From the viewpoint of further improving the effect of the present invention, the content of the carbon black is preferably 35 to 75 parts by mass, more preferably 40 to 70 parts by mass, based on 100 parts by mass of the rubber component.

(vulcanization accelerators)

The composition of the present invention may further contain a vulcanization accelerator.

The vulcanization accelerator is not particularly limited. Examples thereof include a thiazole-based, guanidine-based, thiuram-based or sulfenamide-based vulcanization accelerator.

Among them, the vulcanization accelerator is preferably a thiazole-based vulcanization accelerator, and more preferably dibenzothiazyl disulfide, from the viewpoint that the effect of the present invention is more excellent and further crosslinking of the rubber is not easily promoted after vulcanization.

(content of vulcanization accelerator)

From the viewpoint of more excellent effects of the present invention, the content of the vulcanization accelerator is preferably 0.3 to 1.2 parts by mass, more preferably 0.3 part by mass or more and less than 1.0 part by mass, and still more preferably 0.4 to 0.9 part by mass, relative to 100 parts by mass of the rubber component.

(Sulfur)

The composition of the present invention may also contain sulfur. The sulfur is not particularly limited.

(content of Sulfur)

From the viewpoint of more excellent effects (particularly water-resistant adhesion) of the present invention, the content of sulfur is preferably 2.1 to 5.0 parts by mass, more preferably 2.5 to 4.0 parts by mass, per 100 parts by mass of the rubber component.

The lower limit of the sulfur content may be 2.0 parts by mass or more per 100 parts by mass of the rubber component.

(cobalt borate neodecanoate/sulfur mass ratio)

In the case where the composition of the present invention further contains sulfur, the mass ratio of the content of the cobalt neodecanoate borate to the content of the sulfur (cobalt neodecanoate borate/sulfur) is preferably from 0.24(1.2/5) to 1.7(3.5/2.1), more preferably from more than 0.50 to 1.0 or less, and further preferably from 0.55 to 0.80, from the viewpoint of more excellent effects of the present invention and excellent adhesion to a steel cord.

(rosin, etc.)

From the viewpoint of more excellent effects of the present invention and excellent adhesion to a steel cord, the composition of the present invention preferably further contains at least one selected from the group consisting of rosin, rosin derivatives, phenol resins, and chlorinated paraffins, and more preferably, rosin or rosin derivatives, phenol resins, and chlorinated paraffins are used in combination.

In the present specification, rosin derivatives, phenol resins, and chlorinated paraffins may be collectively referred to as "rosin and the like" hereinafter.

The rosin and the like can function as an adhesion imparting agent.

Rosin, rosin derivatives

Rosin is one of the natural resins also known as rosin.

Examples of the rosin derivatives include: gum rosin (gum rosin), wood rosin, tall oil rosin, a polymer of these rosins, disproportionated rosin, maleated rosin, aldehyde-modified rosin, hydrogenated rosin, and processed products thereof, which are extracted from pine wood with a solvent or the like.

Rosin and rosin derivatives which are generally used as tackifiers can be used.

As the rosin or rosin derivative, a commercially available product can be used. Specifically, examples thereof include: gum rosin or wood rosin manufactured by kazama chemical industries, tall oil rosin manufactured by harmomax chemical industries, hydrogenated rosin manufactured by Hercules, and the like.

From the viewpoint of further improving the effects of the present invention and excellent adhesion to a steel cord, the rosin content is preferably 3 to 10 parts by mass per 100 parts by mass of the rubber component. The content of the rosin derivative is also the same as that of the above rosin.

Phenol formaldehyde resin

As the phenol resin, a phenol resin which can be usually blended in a rubber composition can be used. The phenol resin may include a resin obtained by a reaction between a phenol and an aldehyde, and a modified product thereof. Examples of the phenols include phenol, cresol, xylenol, and resorcinol. Examples of the aldehyde include formaldehyde, acetaldehyde, and furfural.

In a preferred embodiment, the composition of the present invention does not contain a curing agent for a phenolic resin.

From the viewpoint of further improving the effects of the present invention and excellent adhesion to a steel cord, the content of the phenolic resin is preferably 2 to 8 parts by mass per 100 parts by mass of the rubber component.

Chlorinated paraffin

The chlorinated paraffin is not particularly limited as long as it is a paraffin having chlorine. For example, a chain-like saturated hydrocarbon compound having an average carbon number of 26 is mentioned, and all or a part of hydrogen atoms in the compound is substituted by chlorine atoms.

The amount of chlorine contained in the chlorinated paraffin is preferably 40 to 80% by mass, for example, based on the total amount of the chlorinated paraffin.

From the viewpoint of further improving the effect of the present invention and excellent adhesion to a steel cord, the content of the chlorinated paraffin is preferably 3 to 8 parts by mass with respect to 100 parts by mass of the rubber component.

(Total content in the case of combination)

When rosin or a rosin derivative, a phenol resin, and chlorinated paraffin are used in combination, the total content thereof is preferably 8 to 22 parts by mass per 100 parts by mass of the rubber component, from the viewpoint of further improving the effect of the present invention and improving the adhesion to a steel cord.

When rosin or a rosin derivative, a phenol resin, and chlorinated paraffin are used in combination, the content of the phenol resin is preferably 10 to 40% by mass based on the total content of the rosin or the rosin derivative, the phenol resin, and the chlorinated paraffin, from the viewpoint of further improving the effect of the present invention and improving the adhesion to a steel cord.

(Zinc oxide)

The composition of the invention may also contain zinc oxide. The zinc oxide is not particularly limited.

(content of Zinc oxide)

From the viewpoint of further improving the effect of the present invention, the content of the zinc oxide is preferably 5.0 parts by mass or more per 100 parts by mass of the rubber component.

The upper limit of the content of the zinc oxide may be 20 parts by mass or less with respect to 100 parts by mass of the rubber component.

(oil)

The compositions of the present invention may also contain an oil. The above oil is not particularly limited. Examples thereof include paraffin oil (excluding chlorinated paraffin) and aromatic oil.

(oil content)

From the viewpoint of further improving the effect of the present invention, the content of the oil is preferably 2.0 parts by mass or more per 100 parts by mass of the rubber component.

The upper limit of the oil content may be 10 parts by mass or less with respect to 100 parts by mass of the rubber component.

The composition of the present invention may contain, if necessary, additives such as stearic acid and an antioxidant in addition to the above-mentioned essential components within a range not impairing the object of the present invention.

The composition of the present invention can be produced by mixing the above-mentioned essential components, and if necessary, the above-mentioned carbon black and the like using a roll mill or a banbury mixer.

The composition of the present invention can be used for bonding a steel cord (specifically, for example, a galvanized steel cord), for example.

The composition of the present invention is used, for example, vulcanized, together with a steel cord (for example, a galvanized steel cord), whereby a composite body having a vulcanized rubber and a steel cord can be obtained. In the above composite, the vulcanized rubber and the steel cord can be bonded.

Examples of the steel cord include: a steel cord having an untreated surface; a steel cord having a galvanized surface.

The steel cord is preferably a galvanized steel cord from the viewpoint of further excellent effects and excellent rust prevention properties of the present invention.

The wire diameter, the cord diameter, or the like of the steel cord can be appropriately selected.

The temperature at which the composition of the present invention is vulcanized may be, for example, about 140 to 160 ℃.

From the viewpoint of further improving the effects of the present invention (particularly, cold resistance), the brittle temperature of the vulcanizate obtained by vulcanizing the composition of the present invention is preferably-50 ℃ or lower, more preferably-58 ℃ or lower.

In the present invention, the composition of the present invention is press-vulcanized at 153 ℃ and a surface pressure of 2.0MPa for 20 minutes to obtain a vulcanized rubber (sheet having a thickness of 2mm), and the vulcanized rubber is used in accordance with JIS K6261-2: 2017 "vulcanized rubber and thermoplastic rubber-method for solving low temperature characteristics-second section: low temperature impact embrittlement test ", the embrittlement temperature is measured.

The composition of the present invention can be preferably used for the production of a conveyor belt, for example. In the case where the composition of the present invention is used for the production of a conveyor belt, the composition of the present invention is preferably used as a member constituting the conveyor belt, for example, to form a coating rubber layer (cushion rubber) coating a steel cord.

[ conveyor belt ]

Next, the conveyor belt of the present invention will be explained below.

The conveyor belt of the present invention is formed by using the rubber composition for bonding steel cords of the present invention.

Preferably, the conveyor belt of the present invention has a steel cord. From the viewpoint of further improving the effects of the present invention, the steel cord is preferably a steel cord galvanized on a steel cord having an untreated surface.

The rubber composition for bonding a steel cord used in the conveyor belt of the present invention is not particularly limited as long as it is the rubber composition for bonding a steel cord of the present invention.

From the viewpoint of further improving the effects of the present invention, the composition of the present invention preferably forms a coating rubber layer (cushion rubber) coating the steel cord.

As one preferable embodiment, the conveyor belt of the present invention further includes a cover rubber layer. The rubber composition capable of forming the aforementioned cap rubber layer is not particularly limited.

Hereinafter, a conveyor belt according to the present invention will be described with reference to the drawings. The conveyor belt of the present invention is not limited to the accompanying drawings.

FIG. 1 is a cross-sectional perspective view schematically illustrating one example of the conveyor belt of the present invention.

In fig. 1, the conveyor belt 1 has cover rubber layers 6 on both surfaces, and has steel cords 2 and a coating rubber layer 4 between the cover rubber layers 6. The coating rubber layer 4 coats the steel cord 2. The coating rubber layer 4 is preferably formed of the rubber composition for bonding steel cords of the present invention.