Rubber composition for conveyor belt and conveyor belt

Abstract

To provide a rubber composition for conveyor belts that excels in wear resistance after heat aging, elongation at break after heat aging, and breaking strength under heating conditions, and a conveyor belt made using the same.SOLUTION: A rubber composition for conveyor belts contains a rubber component containing an ethylene-1-butene copolymer, carbon black and / or silica, and at least one filler coupling agent selected from the group consisting of a compound represented by formula (1), its metal salt, and a compound represented by formula (2). There is also provided a conveyor belt made using the rubber composition for conveyor belts.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition for a conveyor belt and a conveyor belt.

Background Art

[0002] Conventionally, belt conveyors have been used to continuously convey conveyed materials such as raw materials. Since a belt conveyor generally moves or rotates a belt (conveyor belt) with a driving device such as a roller to convey the conveyed material, the conveyor belt is required to have heat resistance and the like. On the other hand, as a rubber composition capable of forming a conveyor belt, for example, a rubber composition containing an ethylene-olefin rubber has been proposed (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, for conveyor belts used in various environments, the required levels for wear resistance and mechanical properties related to heat resistance have been increasing more and more. Under such circumstances, the present inventor prepared a rubber composition containing an ethylene-olefin rubber or the like with reference to Patent Documents 1 and 2 and evaluated it. As a result, it became clear that the rubber obtained from such a rubber composition may have low wear resistance or elongation at break after heat aging, or low breaking strength under heating conditions.

[0005] Therefore, an object of the present invention is to provide a rubber composition for conveyor belts that has excellent abrasion resistance, elongation at break, and breaking strength under heating conditions after heat aging. Another object of the present invention is also to provide a conveyor belt that has excellent abrasion resistance, elongation at break, and breaking strength under heating conditions after heat aging.

Means for Solving the Problems

[0006] As a result of intensive research to solve the above problems, the present inventors have found that a desired effect can be obtained by a rubber composition containing a rubber component containing an ethylene-1-butene copolymer, carbon black and / or silica, and a filler coupling agent having a specific structure described later, and thus have arrived at the present invention. The present invention is based on the above findings and the like, and specifically solves the above problems with the following configuration.

[0007] [1] A rubber composition for conveyor belts containing a rubber component containing an ethylene-1-butene copolymer, carbon black and / or silica, and at least one filler coupling agent selected from the group consisting of a compound represented by the following formula (1), a metal salt thereof, and a compound represented by the following formula (2) described later. [2] The rubber composition for conveyor belts according to [1], containing the compound represented by the above formula (1). [3] The rubber composition for conveyor belts according to [1] or [2], wherein the content of the above carbon black and / or the above silica is 30 to 80 parts by mass with respect to 100 parts by mass of the above rubber component. [4] The rubber composition for conveyor belts according to any one of [1] to [3], wherein the content of the above filler coupling agent is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the above rubber component. [5] Furthermore, a rubber composition for a conveyor belt according to any one of [1] to [4], containing ethylene-propylene copolymer 2 having an ethylene content of 50 to 80 mol% and a weight average molecular weight of less than 50,000. However, the above rubber component does not include the above ethylene-propylene copolymer 2. [6] The rubber composition for a conveyor belt according to any one of [1] to [5], wherein the above rubber component further includes ethylene-propylene copolymer 1 having a Mooney viscosity at 125 °C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more. [7] The rubber composition for a conveyor belt according to [6], wherein the mass ratio of the above ethylene-1-butene copolymer to the above ethylene-propylene copolymer 1 is 10 / 90 to 90 / 10. [8] The rubber component further includes ethylene-propylene copolymer 1 having a Mooney viscosity at 125 °C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more, The rubber composition for a conveyor belt according to [5], wherein the content of the above ethylene-propylene copolymer 2 is 1 to 20 parts by mass with respect to 100 parts by mass of the above rubber component. [9] Furthermore, a rubber composition for a conveyor belt according to any one of [1] to [8], containing an organic peroxide.

[10] The rubber composition for a conveyor belt according to any one of [1] to [9], wherein the above ethylene-1-butene copolymer has a Mooney viscosity at 125 °C of 15 or more.

[11] A conveyor belt produced using the rubber composition for a conveyor belt according to any one of [1] to

[10] . [Advantages of the Invention]

[0008] The rubber composition for a conveyor belt of the present invention is excellent in abrasion resistance, elongation at break after heat aging, and breaking strength under heating conditions. The conveyor belt of the present invention is excellent in abrasion resistance, elongation at break after heat aging, and breaking strength under heating conditions.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0010] The present invention will be described in detail below. In this specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In this specification, unless otherwise specified, each component used in the present invention can be used alone or in combination of two or more of the substances corresponding to the component. When the component contains two or more substances, the content of the component means the total content of the two or more substances. In this specification, unless otherwise specified, each component is not particularly limited with respect to its production method. For example, conventionally known methods can be mentioned. In this specification, when at least one of the abrasion resistance, elongation at break after heat aging, and breaking strength under heating conditions is more excellent, it may be said that the effect of the present invention is more excellent.

[0011] [Rubber Composition for Conveyor Belt] The rubber composition for a conveyor belt of the present invention (the composition of the present invention) is a rubber component containing an ethylene·1-butene copolymer, carbon black and / or silica, and a rubber composition for a conveyor belt containing at least one filler coupling agent selected from the group consisting of a compound represented by the following formula (1), a metal salt thereof, and a compound represented by the following formula (2). [Chemical formula] In formula (1), n represents an integer from 2 to 10. [Chemical formula] In formula (2), R 1 represents a divalent hydrocarbon group having 6 to 12 carbon atoms which may have a substituent, R 2 , R 3 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxy group or an alkoxy group having 1 to 6 carbon atoms, R 4 represents a hydroxy group or -OM 1 and M 1 represents a metal, X represents -NH- or -O-.

[0012] In the present invention, in the above filler coupling agent, the amino group (-NH2) in each of formula (1) and formula (2) acts on carbon black and / or silica as a filler to improve the dispersibility of the filler. On the other hand, -SO3H or its metal salt in formula (1), or R 4 or the double bond in formula (2) is considered to act on EBM to form a covalent bond or other bond with EBM. The inventor presumes that by the above filler coupling agent having the above actions, the composition of the present invention can achieve the above problems. Hereinafter, each component contained in the composition of the present invention will be described in detail.

[0013] [Rubber component] The composition of the present invention contains a rubber component, and the rubber component includes an ethylene·1-butene copolymer (EBM). From the viewpoint of easy handling in work and more excellent effects of the present invention (especially the breaking strength under heating conditions), the above rubber component is preferably solid under the condition of 23°C. The above rubber component does not contain the ethylene·propylene copolymer 2 described later.

[0014] [Ethylene-1-butene copolymer] The ethylene-1-butene copolymer (EBM) contained in the rubber component is a copolymer of ethylene and 1-butene. One preferred embodiment is that the repeating units constituting EBM are derived only from ethylene and 1-butene.

[0015] (Mooney viscosity of EBM) From the viewpoint that the effects of the present invention (especially the breaking strength under heating conditions) are more excellent and the durability (tear strength) is excellent, the Mooney viscosity of EBM at 125 °C is preferably 15 or more, more preferably 20 or more, and even more preferably 40 or more. Although the upper limit value of the above Mooney viscosity is not particularly limited, from the viewpoint that the effects of the present invention (especially the breaking strength under heating conditions) are more excellent, it is preferably 70 or less, and more preferably 55 or less.

[0016] In the present invention, the Mooney viscosity at 125 °C refers to the viscosity (ML 1+4 , 125 °C) measured under the conditions of using an L-shaped rotor, a preheating time of 1 minute, a rotor rotation time of 4 minutes, and a test temperature of 125 °C in accordance with JIS K6300-1:2013 (the same applies hereinafter). By the above method, the Mooney viscosity of EBM at 125 °C can be measured. The same applies to the Mooney viscosity of EPM1 and EPM2 at 125 °C described later.

[0017] From the viewpoint that EBM is easy to handle in operation and the effects of the present invention (especially the breaking strength under heating conditions) are more excellent, it is preferably solid under the condition of 23 °C.

[0018] (Ethylene content of EBM) The ethylene content of EBM is not particularly limited, but from the viewpoint that the effects of the present invention are more excellent, 60 to 90% by mass in EBM is preferred, and 65 to 85% by mass is more preferred. In the present invention, the ethylene content of the ethylene-1-butene copolymer (EBM) can be calculated based on ASTM D 3900.

[0019] [Ethylene-propylene copolymer] From the viewpoint that the composition of the present invention has more excellent effects of the present invention and excellent processability, it is preferably further contained ethylene-propylene copolymer (EPM). Ethylene-propylene copolymer 1 (EPM1) having a Mooney viscosity at 125 ° C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more, and / or It is more preferable to contain ethylene-propylene copolymer 2 (EPM2) having an ethylene content of 50 to 80 mol% and a weight average molecular weight of less than 50,000. It is more preferable to contain at least the above EPM2. It is particularly preferable to contain EPM2 and EPM1. Incidentally, ethylene-propylene copolymer 1 (EPM1) having a weight average molecular weight of 50,000 or more is a solid rubber under the condition of 23 ° C, and thus is included in the rubber component. On the other hand, as described above, ethylene-propylene copolymer 2 (EPM2) is not included in the rubber component.

[0020] (Ethylene-propylene copolymer 1) Ethylene-propylene copolymer 1 (EPM1) is an ethylene-propylene copolymer (copolymer rubber) having a Mooney viscosity at 125 ° C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more.

[0021] ·Copolymer EPM1 is a copolymer of ethylene and propylene. EPM1 is cited as one of the preferred embodiments in which the repeating units constituting it are derived only from ethylene and propylene.

[0022] ·Mooney viscosity of EPM1 The Mooney viscosity of EPM1 at 125°C is more preferably 25 or more from the viewpoint of excellent heat resistance and more excellent effects of the present invention (particularly breaking strength under heating conditions). The upper limit value of the Mooney viscosity is not particularly limited, but is preferably 50 or less, more preferably 40 or less, from the viewpoints of more excellent effects of the present invention (particularly breaking strength under heating conditions) and excellent heat resistance and processability.

[0023] · Ethylene content of EPM1 The ethylene content of EPM1 is preferably 40% by mass or more and less than 60% by mass, more preferably 45 to 55% by mass, in EPM1 from the viewpoints of more excellent effects of the present invention and excellent heat resistance and processability. In the present invention, the ethylene content of ethylene-propylene copolymer 1 can be calculated based on ASTM D 3900.

[0024] · Weight average molecular weight of EPM1 The weight average molecular weight of EPM1 is preferably 100,000 to 450,000, more preferably 200,000 to 350,000, from the viewpoints of more excellent effects of the present invention and excellent processability.

[0025] In the present invention, the weight average molecular weight of ethylene-propylene copolymer 1 can be made the standard polystyrene conversion value obtained by gel permeation chromatography (GPC) measurement under the following conditions. The same applies to the weight average molecular weight of ethylene-propylene copolymer 2 described later. · Solvent: Tetrahydrofuran · Detector: RI detector

[0026] · Mass ratio of EBM and EPM1 When the rubber component further contains EPM1, the mass ratio of the above EBM to the above EPM1 (EBM / EPM1) can be 10 / 90 to 90 / 10, preferably 15 / 85 to 70 / 30, more preferably 20 / 80 to 50 / 50, still more preferably 25 / 75 to 45 / 55, even more preferably 25 / 75 to 40 / 55, and particularly preferably 25 / 75 to 35 / 65 from the viewpoint that the effects of the present invention (especially the elongation at break after heat aging) are more excellent and the processability and durability (tear strength) are excellent.

[0027] (Ethylene-propylene copolymer 2) From the viewpoint that the composition of the present invention has more excellent effects of the invention (especially the abrasion resistance after heat aging and the elongation at break after heat aging) and excellent processability, it preferably further contains an ethylene content of 50 to 80 mol% and a weight average molecular weight of less than 50,000 (EPM2). In the present invention, it is considered that EPM2 reduces the hardness or viscosity of the rubber component (EBM and EPM1) while moderately crosslinking with EBM and / or EPM1.

[0028] ·Copolymer EPM2 is a copolymer of ethylene and propylene. One preferred embodiment is that the repeating units constituting EPM2 are derived only from ethylene and propylene. EPM2 is preferably liquid under the condition of 23°C. In the present invention, EPM2 does not contain paraffin oil.

[0029] ·Ethylene content of EPM2 The ethylene content of EPM2 is preferably 50 to 80 mol%, more preferably 60 to 80 mol%, and still more preferably 70 to 80 mol% from the viewpoint that the effects of the invention (especially the abrasion resistance after heat aging and the elongation at break after heat aging) are more excellent and the processability and durability (tear strength) are excellent. The above standard of the ethylene content of EPM2 is the total amount (total molar amount) of the repeating units (repeating units by ethylene or propylene) constituting the ethylene-propylene copolymer 2 (EPM2). In the present invention, the ethylene content of EPM2 can be determined from the analysis results by the IR method (infrared spectroscopy).

[0030] · Weight-average molecular weight of EPM2 From the viewpoint that the effects of the present invention are more excellent, the weight-average molecular weight of EPM2 is preferably 3,000 to 30,000, and more preferably 5,000 to 20,000.

[0031] · Content of EPM2 When the composition of the present invention further contains EPM2, the content of EPM2 is preferably 1 to 20 parts by mass, and more preferably 8 to 15 parts by mass, based on 100 parts by mass of the above rubber component, from the viewpoints that the effects of the present invention are more excellent and the processability is excellent. Note that the "100 parts by mass of the rubber component", which is the standard for the content of EPM2 above, does not include the content of EPM2 (the same applies hereinafter).

[0032] When the composition of the present invention further contains EPM1 and EPM2, the content of EPM2 is the same as the content of EPM2 when the composition of the present invention further contains EPM2. Note that the "100 parts by mass of the rubber component", which is the standard for the content of EPM2 above, includes the contents of EBM and EPM1 and does not include the content of EPM2 (the same applies hereinafter).

[0033] [Carbon black and / or silica] The composition of the present invention contains carbon black and / or silica.

[0034] (Carbon black) The carbon black that can be contained in the composition of the present invention is not particularly limited. For example, conventionally known ones can be mentioned.

[0035] · DBP absorption amount From the viewpoint that the effects of the present invention are more excellent, the DBP (dibutyl phthalate) absorption amount of the carbon black is preferably 90 cm 3 / 100 g or more, and preferably 95 cm 3It is more preferably 100 g or more. The DBP oil absorption amount is a value measured according to JIS K6217-4:2017 "Carbon black for rubber - Basic characteristics - Part 4: Method for determining oil absorption amount".

[0036] ·N2SA The N2SA (nitrogen adsorption specific surface area) of the carbon black is preferably 80 m 2 / g or more, and more preferably 110 m 2 / g or more, from the viewpoint that the effects of the present invention are more excellent, low adhesiveness, low friction, excellent processability, low viscosity of the rubber composition and excellent workability. The N2SA of the carbon black is a value measured according to JIS K6217-2:2001 "Carbon black for rubber - Basic characteristics - Part 2: Method for determining specific surface area - Nitrogen adsorption method - Single point method".

[0037] ·Type The carbon black is not particularly limited, but preferably contains ISAF, SAF, FEF, GPF, SRF, FT, HAF, or MT grade carbon black, and more preferably contains at least ISAF (Intermediate Super Abrasion Furnace) or HAF (High Arasion Furnace) grade carbon black.

[0038] (Silica) The silica that can be contained in the composition of the present invention is not particularly limited. For example, conventionally known ones can be mentioned. Specifically, for example, fumed silica, calcined silica, precipitated silica, pulverized silica, fused silica, anhydrous fine silica, hydrated fine silica, hydrated aluminum silicate, hydrated calcium silicate can be mentioned.

[0039] (Preferred embodiment) The composition of the present invention preferably further contains carbon black from the viewpoint that the effects of the present invention are more excellent.

[0040] (Content of carbon black and / or silica) The content of carbon black and / or silica (when carbon black and silica are used in combination, their total content) is preferably 30 to 80 parts by mass, more preferably 30 to 60 parts by mass, based on 100 parts by mass of the rubber component from the viewpoint of more excellent effects of the present invention.

[0041] [Filler coupling agent] The composition of the present invention contains at least one filler coupling agent selected from the group consisting of a compound represented by the following formula (1), a metal salt thereof, and a compound represented by the following formula (2).

[0042] (Compound represented by formula (1)) Regarding the compound represented by formula (1), formula (1) is as follows. [Chemical formula] In formula (1), n represents an integer of 2 to 10. From the viewpoint of more excellent effects of the present invention, n is preferably an integer of 2 to 6, more preferably an integer of 3 to 4.

[0043] Examples of the compound represented by formula (1) include S-(3-aminopropyl)thiosulfuric acid, S-(4-aminobutyl)thiosulfuric acid, S-(5-aminopentyl)thiosulfuric acid, S-(6-aminohexyl)thiosulfuric acid, S-(7-aminoheptyl)thiosulfuric acid, S-(8-aminooctyl)thiosulfuric acid, S-(9-aminononyl)thiosulfuric acid, and S-(9-aminodecyl)thiosulfuric acid.

[0044] (Metal salt of the compound represented by formula (1)) The metal salt of the compound represented by formula (1) is a compound in which -SO3H in the above formula (1) is changed to -SO3M 2 wherein M 2 represents a metal, and examples of M 2 include alkali metals such as sodium and potassium.

[0045] (Compound represented by formula (2)) For the compound represented by formula (2), formula (2) is as follows.

Chemical formula

[0046] ·R 1 In formula (2), R 1 represents a divalent hydrocarbon group having 6 to 12 carbon atoms which may have a substituent. Examples of the above hydrocarbon group include an aliphatic hydrocarbon group (linear, branched, cyclic, or a combination thereof), an aromatic hydrocarbon group, or a combination thereof. The substituent that R 1 may have is not particularly limited. R 1 preferably contains an aromatic hydrocarbon group and more preferably contains a phenylene group from the viewpoint of more excellent effects of the present invention.

[0047] ·R 2 , R 3 In formula (2), R 2 , R 3 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxy group or an alkoxy group having 1 to 6 carbon atoms. Examples of the halogen atom include F, Cl, and Br. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, and a naphthyl group. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentyloxy group, and a hexyloxy group. R 2 and R 3 are preferably hydrogen atoms.

[0048] ·R 4 R 4 represents a hydroxy group or -OM 1 wherein M 1 represents a metal. Examples of the above M 1 include alkali metals such as sodium and potassium. R 4 is preferably -ONa.

[0049] ·X X represents -NH- or -O-. X is preferably -NH-.

[0050] Examples of the compound represented by the formula (2) include sodium (2Z)-4-[(4-aminophenyl)amino]-4-oxo-2-butenoate.

[0051] ·Preferred examples From the viewpoint that the above filler coupling agent has more excellent effects of the present invention and excellent durability (tear strength) and the like, it preferably contains the compound represented by the formula (1), and more preferably contains S-(3-aminopropyl) thiosulfate.

[0052] ·Content of the filler coupling agent The content of the above-mentioned filler coupling agent (when a plurality of compounds selected from the compound represented by formula (1), its metal salt, and the compound represented by formula (2) are used in combination, the total content thereof) is preferably 0.1 to 3.0 parts by mass, more preferably 0.3 to 3.0 parts by mass, and still more preferably 0.5 to 2.5 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of more excellent effects of the present invention and excellent durability (tear strength) and the like.

[0053] (Organic peroxide) From the viewpoint of more excellent effects of the present invention, the composition of the present invention preferably further contains an organic peroxide. The above-mentioned organic peroxide can function as a crosslinking agent. The above-mentioned organic peroxide can generate radicals in the repeating unit derived from ethylene in EBM or EPM that can be further contained as necessary, and the radicals can react with each other to crosslink. When the composition of the present invention further contains an organic peroxide, EBM and the like can be more appropriately crosslinked.

[0054] The organic peroxide is not particularly limited, and conventionally known ones can be used. Specific examples thereof include dicumyl peroxide, di-t-butyl peroxide, 1,3-bis(t-butylperoxyisopropyl)benzene (trade name "Perkadox 14-40", manufactured by Kayaku Akzo Co., Ltd.), n-butyl 4,4'-di(t-butylperoxy)valerate, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and the like.

[0055] ·Content of organic peroxide When the composition of the present invention further contains an organic peroxide, the content of the organic peroxide is preferably 0.007 to 0.024 molar equivalents, more preferably 0.011 to 0.020 molar equivalents with respect to 100 parts by mass of the rubber component from the viewpoint of more excellent effects of the present invention.

[0056] (Optional component) In addition to the above components, the composition of the present invention can contain additives such as zinc oxide, stearic acid, antioxidants, oils such as paraffin oil, plasticizers, and co-crosslinking agents such as metal carboxylates, within a range that does not impair the object of the present invention. The content of these additives can be appropriately determined within a range that does not impair the object of the present invention.

[0057] (Co-crosslinking agent) When the composition of the present invention contains an organic peroxide, it can further contain a co-crosslinking agent. The co-crosslinking agent refers to a monomer having a plurality of functional groups. The composition of the present invention preferably further contains the co-crosslinking agent together with the above organic peroxide, because the co-crosslinking agent can crosslink the rubber component and the like, and from the viewpoint that the effects of the present invention are more excellent.

[0058] Examples of the co-crosslinking agent include organometallic compounds and organic compounds (excluding those containing metals). Examples of the organometallic compounds include metal carboxylates, and specifically, di(meta)acrylate metal salts such as magnesium di(meta)acrylate and zinc di(meta)acrylate. Examples of the organic compounds (excluding those containing metals) include (meta)acrylate compounds such as trimethylolpropane triacrylate, ethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate, quinone dioxime compounds, and diallyl compounds.

[0059] The co-crosslinking agent preferably contains an organometallic compound, more preferably contains a di(meta)acrylate metal salt, and even more preferably contains magnesium di(meta)acrylate, because the effects of the present invention are more excellent.

[0060] (Content of co-crosslinking agent) When the composition of the present invention further contains a co-crosslinking agent, the content of the co-crosslinking agent is preferably 0.5 to 5.0 parts by mass with respect to 100 parts by mass of the rubber component for the reason that the effects of the present invention are more excellent. Note that the co-crosslinking agent does not include the above-described filler coupling agent.

[0061] The composition of the present invention can be produced by known conditions and methods. For example, the composition of the present invention can be produced by mixing the above-described respective components using a Banbury mixer, kneader, roll, or the like.

[0062] Using the composition of the present invention, for example, a conveyor belt can be produced.

[0063] [Conveyor Belt] Next, the conveyor belt of the present invention will be described. The conveyor belt of the present invention is a conveyor belt produced using the composition of the present invention. Its shape, manufacturing method, etc. are the same as those of known conveyor belts, for example.

[0064] There is no particular limitation on which constituent member of the conveyor belt of the present invention the composition of the present invention is applied to. It is sufficient that all or part of the rubber constituting the conveyor belt of the present invention is formed of the composition of the present invention. Since the composition of the present invention is excellent in abrasion resistance after heat aging, elongation at break after heat aging, and breaking strength under heating conditions as described above, the conveyor belt of the present invention is cited as one of the preferred embodiments having cover rubber formed using the composition of the present invention.

[0065] Embodiments of the conveyor belt of the present invention will be described below with reference to the accompanying drawings. Note that the present invention is not limited to the accompanying drawings. Figure 1 is a cross-sectional view of an embodiment of the conveyor belt of the present invention. As shown in Figure 1, the first embodiment of the conveyor belt of the present invention is a conveyor belt 4 in which a cloth layer 1 is coated with a coat rubber (adhesive rubber) 2 to form a core material layer, and the outer periphery thereof is covered with a cover rubber 3. The cover rubber 3 is preferably formed from the composition of the present invention. In Figure 1, the conveyor belt 4 has a cloth layer 1 as a core material, and the number of laminated sheets of the cloth layer 1, the thickness of the cover rubber 3, the belt width, etc. can be appropriately determined according to the purpose of use. Examples of the cloth layer include canvas made of a woven fabric of synthetic fibers such as nylon, vinylon, and polyester. In the normal case, the thicknesses T1 and T2 of the cover rubber 3 can be about 1.5 to 20 mm respectively.

[0066] Also, as the coat rubber 2, a coat rubber used in a known conveyor belt can be used. Examples of the coat rubber include rubber compositions containing natural rubber (NR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), ethylene-propylene rubber (EPT), ethylene-propylene-diene rubber (EPDM), etc. as rubber components.

[0067] Next, a second embodiment of the conveyor belt of the present invention will be described with reference to Figure 2. Figure 2 is a cross-sectional view of another embodiment of the conveyor belt of the present invention. As shown in Figure 2, the second embodiment of the conveyor belt of the present invention is a conveyor belt 8 in which a steel cord 5 is coated with a cushion rubber (adhesive rubber) 6 to form a core material layer, and the outer periphery thereof is covered with a cover rubber 7. The cover rubber 7 is preferably formed from the composition of the present invention. The conveyor belt 8 can be formed with a core material by arranging about 50 to 230 steel cords 5 having a diameter of about 2.0 to 9.5 mm formed by twisting a plurality of strands having a diameter of about 0.2 to 0.4 mm in parallel. Generally, the total thickness T of the conveyor belt 8 can be about 10 to 50 mm. Further, as the cushion rubber 6, for example, an adhesive rubber that can be adhered to a zinc-plated steel cord used for a known steel conveyor belt can be used. Specifically, as the cushion rubber, for example, a rubber composition containing natural rubber (NR), acrylonitrile-butadiene rubber (NBR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), etc. as rubber components can be used.

[0068] The conveyor belt of the present invention can be manufactured, for example, by interposing a cloth layer, a steel cord, or a core material layer serving as a core material between unvulcanized rubber sheets formed with the composition of the present invention according to a conventional method, and heating and pressurizing them for vulcanization. The vulcanization conditions can be, for example, about 120 to 180 °C and about 0.1 to 4.9 MPa for about 10 to 90 minutes.

[0069] Since the conveyor belt of the present invention is produced using the composition of the present invention described above, it has excellent abrasion resistance after heat aging, elongation at break after heat aging, and breaking strength under heating conditions.

Examples

[0070] The present invention will be specifically described below with reference to examples. However, the present invention is not limited thereto.

[0071] [Manufacture of Composition] Using each component in the following Table 1 in the composition shown in the same table (parts by mass except for crosslinking agent 1), these were mixed with a Banbury mixer to produce each composition. In Table 1, the amount of crosslinking agent 1 is the molar equivalent to 100 parts by mass of the total content of rubber components (EBM1, EBM2, EPM1-1, EPDM) shown in Table 1.

[0072] [Evaluation] The following evaluations were performed using each composition manufactured as described above. The results are shown in Table 1.

[0073] <Abrasion Resistance after Heat Aging> · Preparation of Initial Vulcanization Specimen Each of the compositions obtained as described above was vulcanized for 45 minutes under a surface pressure of 3.0 MPa using a press molding machine at 160 °C to prepare an initial vulcanized test piece with a diameter of 16 mm and a thickness of 6 mm.

[0074] · Heat aging test An heat aging test was conducted by placing each of the initial vulcanized test pieces obtained as described above at 180 °C for 168 hours. The samples obtained after the heat aging test are referred to as "vulcanized test pieces after heat aging".

[0075] · Abrasion test Using each of the vulcanized test pieces after heat aging obtained as described above as a sample for evaluating abrasion resistance, an abrasion test (Method A, non-rotating type) was conducted at 23 °C using a DIN abrasion tester in accordance with JIS K6264-2:2005, and the abrasion loss [mm 3 was measured. The results are shown in the column of "DIN abrasion resistance after heat aging (180 °C × 168 hr)" in Table 1.

[0076] · Evaluation criteria In the present invention, when the abrasion loss was less than 170 mm 3 , it was evaluated that the abrasion resistance after heat aging was excellent. In the above case, the smaller the abrasion loss, the better the abrasion resistance after heat aging. On the other hand, when the abrasion loss was 170 mm or more 3 , it was evaluated that the abrasion resistance after heat aging was poor.

[0077] <Preparation of samples for evaluating tensile properties> · Initial samples for evaluating tensile properties Each of the compositions obtained as described above was vulcanized for 45 minutes under a surface pressure of 3.0 MPa using a press molding machine at 160 °C to prepare a vulcanized sheet with a thickness of 2 mm. A JIS No. 3 dumbbell-shaped test piece was punched out from this sheet to obtain an initial sample for evaluating tensile properties.

[0078] · Samples for evaluating tensile properties after heat aging (180 °C × 336 hours) A heat aging test was conducted on each of the initial tensile property evaluation samples obtained as described above by placing them at 180°C for 336 hours. The samples obtained after the heat aging test are referred to as "tensile property evaluation samples after heat aging".

[0079] <Tensile Test 1: Evaluation of Elongation at Break after Heat Aging> · Elongation at Break (EB) after heat aging (180°C × 336 hours) For each of the tensile property evaluation samples after heat aging obtained as described above, a tensile test was conducted at a tensile speed of 500 mm / min under the condition of 23°C in accordance with JIS K6251:2017, and the elongation at break (EB, unit: %) after heat aging was measured. The results are shown in the column of "Elongation at Break EB after Heat Aging (180°C × 336 hr)" in Table 1. In the present invention, when the above EB was 280% or more, it was evaluated that the elongation at break after heat aging was excellent. The larger the above EB is than 280%, the more excellent the elongation at break after heat aging is. On the other hand, when the above EB was less than 280%, it was evaluated that the elongation at break after heat aging was poor.

[0080] <Tensile Test 2: Evaluation of Tensile Strength under Heating Conditions> · Tensile strength at room temperature or under heating conditions For each of the initial tensile property evaluation samples obtained as described above, a tensile test was conducted at a tensile speed of 500 mm / min under the condition of 23°C or 150°C in accordance with JIS K6251:2017, and the tensile strength (TB, unit: MPa) was measured. In Table 1, the results of the tensile strength under the condition of 23°C are shown in the column of "TB@23°C", and the results of the tensile strength at the time of heating under the condition of 150°C are shown in the column of "TB@150°C".

[0081] · Evaluation of tensile strength under heating conditions In the present invention, the tensile strength under heating conditions was evaluated by the above TB@150°C. In the present invention, when the result of TB@150°C was 4.1 MPa or more, it was evaluated that the breaking strength under heating conditions was excellent. The larger the TB@150°C is than 4.1 MPa, the more excellent the breaking strength under heating conditions is. On the other hand, when the result of TB@150°C was less than 4.1 MPa, it was evaluated that the breaking strength under heating conditions was poor.

[0082] · ΔTB (rate of change of TB [%]) The value of TB measured under the conditions of 23°C or 150°C, which was measured as described above, was applied to the following formula to obtain the rate of change of TB [%]. The results are shown in the "ΔTB" column of Table 1. Rate of change of TB (%) = {((TB measured under the condition of 150°C) - (TB measured under the condition of 23°C)) / (TB measured under the condition of 23°C)} × 100 In the present invention, the closer the absolute value of the rate of change of TB is to 0%, the more excellent the heat resistance is, which is preferable.

[0083] · Measurement of tear strength (Ts) Using each of the compositions obtained as described above, in accordance with JIS K6252-1:2015, using a crescent-shaped test piece, the tear strength (unit: kN / m) was measured under the conditions of 23°C and 150°C. The measurement results under the condition of 23°C are shown in the column of "Ts@23°C" in Table 1. The measurement results under the condition of 150°C (high temperature) are shown in the column of "Ts@150°C" in Table 1.

[0084] · Evaluation of tear strength (Ts) Under the condition of 23°C, the larger the value of the tear strength is, the more excellent the durability under room temperature conditions is, which is preferable. Under the condition of 150°C, the larger the value of the tear strength is, the more excellent the durability under high temperature conditions is, which is preferable.

[0085]

Table 1

[0086]

Table 2

[0087]

Table 3

[0088] The details of each component shown in Table 1 are as follows. (EBM) · EBM1: An ethylene·1-butene copolymer having a Mooney viscosity of 19 at 125°C and an ethylene content of 74% by mass. Trade name "Engage 7467" (manufactured by Dow Chemical Company). It is solid under the condition of 23°C.

[0089] · EBM2: An ethylene·1-butene copolymer having a Mooney viscosity of 47 at 125°C and an ethylene content of 74% by mass. Trade name "Engage 7487" (manufactured by Dow Chemical Company). It is solid under the condition of 23°C.

[0090] (EPM1) · EPM1-1: An ethylene·propylene copolymer having a Mooney viscosity of 26 at 125°C, an ethylene content of 52% by mass, and a weight-average molecular weight of 310,000. Trade name "KEP-110" (manufactured by KUMHO POLYCHEM). The above EPM1-1 is an ethylene·propylene copolymer having a Mooney viscosity of 20 or more at 125°C, an ethylene content of 40 to 60% by mass, and a weight-average molecular weight of 50,000 or more, and thus corresponds to ethylene·propylene copolymer 1 in the present invention. It is solid under the condition of 23°C.

[0091] (EPM2) · EPM2-1: Liquid rubber @ 23°C. Trade name "Lucant HC-2000" (manufactured by Mitsui Chemicals). An ethylene·propylene copolymer having an ethylene content of 53 mol% and a propylene content of 47 mol% and a weight-average molecular weight of less than 50,000. It is liquid under the condition of 23°C.

[0092] ·EPM2-2: Liquid rubber at 23 °C. Trade name "Lucant HC-3000X" (manufactured by Mitsui Chemicals, Inc.). An ethylene-propylene copolymer with an ethylene content of 73 mol% and a propylene content of 27 mol%, and a weight-average molecular weight of less than 50,000. It is liquid under the condition of 23 °C.

[0093] ·EPDM (for comparison): EPDM. KELTAN 5170P manufactured by Arlanxeo

[0094] (Filler coupling agent) ·Filler coupling agent 1: S-(3-aminopropyl) thiosulfuric acid. Trade name Sumilink 100, manufactured by Sumitomo Chemical Co., Ltd. ·Filler coupling agent 2: Sodium (2Z)-4-[(4-aminophenyl)amino]-4-oxo-2-butenoate. Trade name Sumilink 200, manufactured by Sumitomo Chemical Co., Ltd.

[0095] ·Carbon black: HAF grade carbon black. Trade name "Nitron #300" (manufactured by Shin Nippon Carbon Co., Ltd.)

[0096] ·Zinc oxide: Trade name "Zinc Oxide Type 3" (manufactured by Sho Do Chemical Industry Co., Ltd.) ·Stearic acid: Trade name "Stearic Acid 50S" (manufactured by Chiba Fatty Acids Co., Ltd.) ·Antioxidant 1: Trade name "No Crack MMB" (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) ·Antioxidant 2: Trade name "Nonflex LAS-P" (manufactured by Seiko Chemical Co., Ltd.) ·Oil: Trade name "SUNPAR 2280" (manufactured by Nippon Sun Oil Co., Ltd.) paraffin oil

[0097] ·Crosslinking agent 1: Trade name "Perkadox 14-40" (manufactured by Chemische Fabrik Stockhausen GmbH) organic peroxide ·Crosslinking agent 2 (co-crosslinking agent): Trade name "Hycross GT" (manufactured by Seiko Chemical Co., Ltd.) metal carboxylate (magnesium dimethacrylate)

[0098] (Evaluation of processability) The rubber compositions (unvulcanized) of Examples 2 and 5 to 9 were in accordance with JIS K6300-2:2001 "Unvulcanized Rubber - Physical Properties - Part 2: Method for Determining Vulcanization Characteristics by Oscillating Disk Rheometer". Using a rotorless vulcanization tester as a rheometer, at a temperature of 160 °C, a vulcanization curve with the obtained torque on the vertical axis and the vulcanization time on the horizontal axis was measured. The maximum value MH of the torque was obtained from the obtained vulcanization curve. In the present invention, when the maximum value MH is less than 1, it means that the processability is excellent. The smaller the maximum value MH, the better the processability. The results are shown below. (Results of the maximum torque value MH / Unit is "N·m") Example 2 0.94 Example 5 0.88 Example 6 0.91 Example 7 0.91 Example 8 0.89 Example 9 0.88

[0099] As is clear from the results shown in Table 1, Comparative Example 1, which does not contain EBM, contains EPM instead, and does not contain a predetermined filler coupling agent, had poor abrasion resistance after heat aging and elongation at break under heating conditions. The elongation at break under heating conditions was poor. Comparative Examples 2 and 3, which do not contain EBM and contain EPM instead, had poor abrasion resistance after heat aging. In Comparative Example 3, the elongation at break under heating conditions was also poor. Comparative Example 4, which does not contain EBM and contains EPM instead, had poor abrasion resistance after heat aging. Comparative Example 5, which does not contain a predetermined filler coupling agent, had poor elongation at break under heating conditions. Comparative Example 6, which does not contain EBM and contains EPDM instead, had poor elongation at break after heat aging.

[0100] On the other hand, the composition of the present invention was excellent in abrasion resistance after heat aging, elongation at break after heat aging, and breaking strength under heating conditions. Moreover, the composition of the present invention had excellent processability.

Explanation of Symbols

[0101] 1: Fabric layer 2: Coating rubber 3,7: Cover rubber 4,8: Conveyor belt 5: Steel cord 6: Cushion rubber

Claims

1. A rubber component containing an ethylene-1-butene copolymer, carbon black, and a conveyor belt rubber composition containing at least one filler coupling agent selected from the group consisting of a compound represented by the following formula (1), a metal salt thereof, and a compound represented by the following formula (2). 【Chemical 1】 In formula (1), n represents an integer of 2 to 10. [Chemical 2] In formula (2), R 1 represents a divalent hydrocarbon group having 6 to 12 carbon atoms which may have a substituent, R 2 、 R 3 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, a hydroxy group or an alkoxy group having 1 to 6 carbon atoms, R 4 represents a hydroxy group or -OM 1 , M 1 represents a metal, X represents -NH- or -O-.

2. The conveyor belt rubber composition according to claim 1, containing the compound represented by the formula (1).

3. The conveyor belt rubber composition according to claim 1 or 2, wherein the content of the carbon black is 30 to 80 parts by mass with respect to 100 parts by mass of the rubber component.

4. The conveyor belt rubber composition according to any one of claims 1 to 3, wherein the content of the filler coupling agent is 0.1 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component.

5. Furthermore, the conveyor belt rubber composition according to any one of claims 1 to 4, containing an ethylene-propylene copolymer 2 having an ethylene content of 50 to 80 mol% and a weight average molecular weight of less than 50,000. However, the rubber component does not include the ethylene-propylene copolymer 2.

6. The conveyor belt rubber composition according to any one of claims 1 to 5, wherein the rubber component further includes an ethylene-propylene copolymer 1 having a Mooney viscosity at 125 °C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more.

7. The conveyor belt rubber composition according to claim 6, wherein the mass ratio of the ethylene-1-butene copolymer to the ethylene-propylene copolymer 1 is 10 / 90 to 90 / 10.

8. The rubber component further includes an ethylene-propylene copolymer 1 having a Mooney viscosity at 125 °C of 20 or more, an ethylene content of 40 to 70% by mass, and a weight average molecular weight of 50,000 or more. The conveyor belt rubber composition according to claim 5, wherein the content of the ethylene-propylene copolymer 2 is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

9. Furthermore, the conveyor belt rubber composition according to any one of claims 1 to 8, containing an organic peroxide.

10. The rubber composition for a conveyor belt according to any one of claims 1 to 9, wherein the ethylene-1-butene copolymer has a Mooney viscosity at 125°C of 15 or more.

11. A conveyor belt produced using the rubber composition for a conveyor belt according to any one of claims 1 to 10.

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