JP2000355415A - Heat resistant conveyor belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat resistant conveyor belt with superior heat resistance compared with conventional products by mixing EPDM with two cross linking agents of organic peroxide and sulfur in an adhesive rubber layer between upper and lower cover rubbers. SOLUTION: In this heat resistant conveyor belt comprising an adhesive rubber layer 2 having a steel cord 1 as a core body and cover rubbers 3 vulcanized and adhered to upper and lower faces of the adhesive rubber layer 2, ethylene propylene diene rubber used as a rubber component and organic peroxide and a sulfur-based vulcanizing agent used as cross linking agents are mixed in the adhesive rubber layer 2, and ethylene propylene rubber used as a rubber component and organic peroxide used as a vulcanizing agent are mixed in the upper and lower cover rubbers 3. If the steel cord 1 is a galvanized steel cord, an adhesion accelerator comprising hydrate inorganic salt and metallic salt of organic acid including at least one metal selected from a group consisting of Zn, K, Al, and Ti is mixed in the adhesive rubber layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant conveyor belt having a steel cord as a core.

[0002]

2. Description of the Related Art Conveyor belts comprising a crosslinked rubber obtained by crosslinking a rubber compound containing ethylene-propylene rubber (EPM) as a main rubber component with an organic peroxide have been widely used as heat-resistant belts. As a reinforcing material for this purpose, in recent years, with the lengthening of conveyor belts and the increase in applications requiring high tension, steel cords have been used.
Propylene rubber conveyor belts have come into wide use.

[0003] However, even if ethylene-propylene rubber is blended with an organic acid cobalt which has been used as an adhesive between a diene rubber and a galvanized steel cord, it cannot be zinc-plated under organic peroxide crosslinking. It could not be directly vulcanized to steel cord.

[0004] Therefore, a heat-resistant conveyor belt made of ethylene-propylene rubber (EPM) having a zinc-plated steel cord as a core has conventionally been made of ethylene-propylene-ethylene.
A mixture of diene rubber (EPDM) and styrene / butadiene rubber (SBR) is blended with organic acid cobalt together with sulfur to form an adhesive rubber composition for galvanized steel cord and covers an EPM rubber containing organic peroxide. The rubber composition was manufactured by vulcanizing and bonding them. FIG. 1 shows a cross-sectional structure of such a heat-resistant conveyor belt.
The cover rubber 3 is vulcanized and bonded to the upper and lower surfaces of the adhesive rubber layer 2 in which is embedded.

[0005]

As described above, in a high-temperature heat-resistant steel cord belt for transporting a high-temperature transport object, EPM rubber which is a heat-resistant polymer is provided as upper and lower covers, and the steel cord adhesive rubber is provided. EPDM sulfur-vulcanized rubber is also applied to impart heat resistance and adhesion.

[0006] However, in the conventional product, when a high-temperature conveyed product (150 to 230 ° C) is conveyed during operation, at that time, a gap between the upper and lower cover rubbers and the adhesive rubber layer, or a galvanized steel cord and the adhesive rubber layer is formed. The deterioration of the bonding performance due to the thermal deterioration of the interface was unavoidable.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a heat-resistant conveyor belt having more excellent heat resistance than conventional products.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, EPDM and a crosslinking agent of both organic peroxide and sulfur were added to the conventional adhesive rubber layer between the upper and lower cover rubbers. It has been found that the addition of (1) and (2) improves the heat resistance and at the same time can prevent the deterioration of the adhesive performance due to the thermal deterioration during the operation of the belt. Further, when the steel cord embedded in the adhesive rubber layer is galvanized, it has been found that the same effect as described above can be obtained by blending a specific adhesion promoter in addition to the above, and the present invention has been found. It was completed. That is, the present invention is as described below.

(1) A heat-resistant conveyor belt comprising an adhesive rubber layer having a steel cord as a core and a cover rubber vulcanized to the upper and lower surfaces of the adhesive rubber layer,
The adhesive rubber layer is mixed with a) an ethylene / propylene / diene rubber as a rubber component, and b) an organic peroxide and a sulfur-based vulcanizing agent as a cross-linking agent. A heat-resistant conveyor belt characterized in that ethylene-propylene rubber as the above and n) an organic peroxide as a vulcanizing agent are blended.

(2) A heat-resistant conveyor belt comprising an adhesive rubber layer having a galvanized steel cord as a core and a cover rubber vulcanized and bonded to the upper and lower surfaces of the adhesive rubber layer. a) ethylene-propylene-diene rubber as a rubber component, b) organic peroxide and sulfur-based vulcanizing agent as a crosslinking agent, c) Zn,
A metal salt of an organic acid containing at least one metal selected from the group consisting of K, Al, Ti and Zr, and an adhesion promoter containing a water-containing inorganic salt; M) ethylene as a rubber component
A heat-resistant conveyor belt comprising propylene rubber and n) an organic peroxide as a vulcanizing agent.

(3) In the heat-resistant conveyor belt of the above (2), the adhesion promoter is 2.0 × 10 4 in terms of metal in the metal salt of the organic acid as the component per 100 g of the rubber component. ^{−4 to} 2.0 × 10 ⁻² mol, and 2.5 × 10 ⁻³ to 2.5 × 1 in terms of water in the water-containing inorganic salt.
0 is a heat-resistant conveyor belt is ^-1 mol.

(4) In the heat-resistant conveyor belt of (2) or (3), d) is further added to the adhesive rubber layer.
It is a heat-resistant conveyor belt containing an organic molybdenum compound.

(5) The heat-resistant conveyor belt according to (2), which contains an organic molybdenum compound in place of the water-containing inorganic salt in the component of the adhesion promoter in (c).

(6) In the heat-resistant conveyor belt of the above (5), the adhesion promoter is 2.0 × 10 4 in terms of metal in the metal salt of the organic acid as the component per 100 g of the rubber component. ^{−4 to} 2.0 × 10 ⁻² mol, and 2.0 × 1 in terms of molybdenum in the organic molybdenum compound.
A thermostable conveyor belt is 0 ^-6 to 2.0 × 10 mol.

(7) In the heat-resistant conveyor belt according to any one of (1) to (6), the adhesive rubber layer contains 0.1 to 20 parts by weight of an organic peroxide per 100 parts by weight of a rubber component. This is a heat-resistant conveyor belt containing 0.1 to 15 parts by weight of a sulfur vulcanizing agent.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the heat-resistant conveyor belt of the present invention will be described in detail. In the heat-resistant conveyor belt according to one embodiment of the present invention, as shown in the cross-sectional structure shown in FIG. 1, a cover rubber 3 is vulcanized and adhered to upper and lower surfaces of an adhesive rubber layer 2 in which a steel cord 1 is embedded. Have been.

In the compounding material which can be used in the present invention, the ethylene-propylene-diene rubber (EPDM) containing a tertiary diene component is used as the polymer rubber component in addition to the ethylene-propylene rubber (EPM). The third diene component is a non-conjugated diene having 5 to 20 carbon atoms, such as 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 2,5-dimethyl-1,
5-hexadiene and 1,4-octadiene, for example, 1,4-cyclohexadiene, cyclooctadiene,
Examples thereof include cyclic dienes such as dicyclopentadiene, and alkenyl norbornenes such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-methacryl-5-norbornene and 2-isopropenyl-5-norbornene. In the above diene,
Dicyclopentadiene, 5-ethylidene-2-norbornene and the like are preferably used. In addition to these rubbers, other rubbers may be contained as long as the rubber properties are not deteriorated.

Examples of the organic peroxide as a crosslinking agent include benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide. 2,5-dimethyl-2,5-di (t-butylperoxy) hexane,
2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 or 1,3-bis (t-butylperoxy) Oxypropyl) benzene, di-t-
Butylperoxy-diisopropylbenzene, t-butylperoxybenzene, 2,4-dichlorobenzoyl peroxide, 1,1-di-t-butylperoxy-
3,3,5-trimethylsiloxane, n-butyl-4,
4-Di-t-butyl peroxyvalerate and the like can be used. Of these, dicumyl peroxide, t-butylperoxybenzene and di-t-butylperoxy-diisopropylbenzene are preferred.

Examples of the sulfur vulcanizing agent include sulfur, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and 2-
(4-morpholinodithio) benzothiazole and the like can be used. Of these, sulfur is preferred. The sulfur is not particularly limited, and for example, powdered sulfur or insoluble sulfur can be used.

As the crosslinking aid, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate and the like are used.
These impart excellent heat aging resistance to the conveyor belt.

In the conveyor belt of the present invention, when a galvanized steel cord is used as a reinforcing material,
The adhesion promoter of c) is contained in the adhesive rubber layer.

That is, the adhesion promoter of the above c) according to the present invention is as follows. B) The organic acid constituting the metal salt of the organic acid containing at least one metal selected from the group consisting of Zn, K, Al, Ti and Zr is not particularly limited, and may be saturated, unsaturated, Alternatively, it may be linear or branched. Furthermore, bulky fatty acids having a naphthene ring, a benzene ring or the like may be used. Specific examples include neodecanoic acid, stearic acid, naphthenic acid, rosin, tall oil acid, oleic acid, linoleic acid, linolenic acid, and the like. When the metal is polyvalent, a part of the organic acid can be replaced with a boron-containing compound such as boric acid.

The metals constituting the metal salt of the organic acid according to the present invention are Zn, K, Al, Ti and Zr, which are advantageous in safety, cost and the like.
The metal salts of these organic acids include those in which a plurality of different or the same metals are bonded in one molecule, and can be used alone or in combination.

(B) The compound form of the organic molybdenum compound is not particularly limited, and examples thereof include organic molybdenum sulfur compounds containing phosphorus and nitrogen such as molybdenum dithiophosphate (Mo-DTP) or molybdenum dithiocarbamate, and molybdenum salts of organic acids. Examples can be given.
As the organic acids, those listed above can be similarly exemplified.

Further, as a component of the adhesion promoter of c),
In the case of containing a metal salt of an organic acid and an organic molybdenum compound, molybdenum and at least one metal selected from the group consisting of Zn, K, Al, Ti and Zr coexist in one molecule. Even if they are connected to each other, they may be used.

[0026] c) as the hydrous inorganic salt, NiSO ₄ · 7
H ₂ O, CoSO ₄ .7H ₂ O, NaSO ₄ .10H _{2
O, CaSO 4 · 2H 2 O} , CuSO 4 · 5H 2 O, A
_{l 2 (SO 4) 3 ·} 18H 2 O, FeSO 4 · 7H
_{2 O, ZnSO 4 · 7H 2} O, MgSO 4 · 7H 2 O,
Na ₂ S · 9H ₂ O, Na ₃ PO ₄ · 12H ₂ O, Na
_{H 2 PO 4 · 2H 2 O} , Na 2 HPO 4 · 12H 2 O,
_{Ni 3 (PO 4) 2 ·} 8H 2 O, Mg 3 (PO 4) 2 ·
_{8H 2 O, Li 3 PO 4} · 5H 2 O, Na 4 P 2 O 7 ·
_{10H 2 O, Ni 2 P 2} O 7 · 6H 2 O, Mn 4 (P 2
_{O 7) 3 · 14H 2 O} , CoCO 3 · 6H 2 O, NiC
_{O 3 · 6H 2 O, Na} 2 CO 3 · 10H 2 O, Nd
_{2 (CO 3) 3 · 8H} 2 O, Na 2 SO 3 · 7H 2 O,
_{CaCl 2 · 6H 2 O, NiCl} 2 · 6H 2 O, Na 2
_{B 4 O 7 · 10H 2 O} , FeCl 3 · 6H 2 O, Na 2
Can be exemplified SiO ₃ · 9H ₂ O and the like. When such a water-containing inorganic salt is blended, the H ₂ O contained therein is released, so that a synthetic rubber having a relatively low moisture content is blended or water is secured even in winter when the air is dry. Therefore, it is considered that a decrease in the adhesive strength can be avoided. It is also effective for improving the adhesive strength immediately after vulcanization, that is, the initial adhesive strength.

When a metal salt of an organic acid and a hydrated inorganic salt are contained as components of the adhesion promoter of c), water (H ₂ O) in the hydrated inorganic salt and a metal in the metal salt of the organic acid are used. The molar ratio (H ₂ O / Me) to (Me) is preferably from 0.1 to 100. If the molar ratio is less than 0.1, a sufficient effect may not be obtained, and the molar ratio may exceed 100. This is because the water content becomes too large, and the adhesiveness may decrease. From the same viewpoint, it is more preferably 1 to 50, and still more preferably 5 to 20.

When a metal salt of an organic acid and an organic molybdenum compound are contained as components of the adhesion promoter of c), the molybdenum (Mo) in the organic molybdenum compound and the metal in the metal salt of the organic acid are used. (Me) (Mo / M)
It is preferable that e) is 0.01 to 100. This is because, when the molar ratio is less than 0.01, the effect of blending the molybdenum compound is not obtained, and when the molar ratio exceeds 100, the effect is not so different. This is because the cost is increased, which is inconvenient from an economic viewpoint. From a similar perspective,
More preferably, it is 0.03-10, and still more preferably, it is 0.0-3.
05 to 1.0.

Further, when a water-containing inorganic salt and an organic molybdenum compound are contained as the adhesion promoter of c), water (H ₂ O) in the water-containing inorganic salt and molybdenum (Mo) in the organic molybdenum compound are used. Has a molar ratio (H ₂ O / Mo) of 1 to
It is preferably 500, because if it is out of this range, the synergistic effect will be lost. From the same viewpoint, more preferably 10 to 100, further preferably 2
5 to 75.

The compounding ratio of the adhesion promoter to the rubber component in c) is as follows. That is, when a metal salt of an organic acid is contained as a component of the adhesion promoter, 100 g of the rubber component is 2.0 × 10 ⁻⁴ to 2.10 ⁻⁴ in terms of metal in the metal salt of the organic acid. The amount is preferably 0 × 10 ⁻² mol, but if it is less than 2.0 × 10 ⁻⁴ mol, the effect may not be sufficiently obtained.
Even if it is added more than ^-2 mol, the effect does not change much,
This is because the cost increases. From the same viewpoint, it is more preferably 4.0 × 10 ^{−4 to} 1.0 × 10 ⁻² mol, and still more preferably 1.0 × 10 ^{−3 to} 4.0 × 10 ⁻³ mol.

When a water-containing inorganic salt is contained as a component of the adhesion promoter in c), 2.5 × 10 ⁻³ to 100 g of the rubber component is converted into water in the water-containing inorganic salt.
2.5 is preferably a × ^{10 -1} mol, which is less than 2.5 × ^{10 -3} mol may sufficient effect can not be obtained, beyond 2.5 × ^{10 -1} mol Even if it is blended, the effect does not change much, but rather the water content becomes too large, and the adhesiveness may be reduced. From the same viewpoint, more preferably 5.0 × 10 ^{−3 to} 2.0.
× 10 ^-1 mol, more preferably 7.5 × 10 ^-3 ×
7.5 × 10 ^-2 mol.

Further, as a component of the adhesion promoter of c),
When an organic molybdenum compound is contained, the rubber component 1
The amount is preferably 2.0 × 10 ^{−6 to} 2.0 × 10 mol in terms of molybdenum in the organic molybdenum compound with respect to 00 g, but this is less than 2.0 × 10 ⁻⁶ mol. The effect may not be sufficiently obtained, and 2.0 × 10
This is because, even if it is added in a molar amount, the effect does not change much and the cost increases. From the same viewpoint, it is more preferably 2.0 × 10 ^{−5 to} 2.0 × 10 ⁻² mol, and still more preferably 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻³ mol.

In the present invention, in each of the adhesive rubber layer 2 and the cover rubber 3, in addition to the above components, a compounding agent usually used in the rubber industry can be appropriately compounded in a usual compounding amount. Specifically, fillers such as carbon black and silica, softeners such as aroma oil, guanidines such as diphenylguanidine, thiazoles such as mercaptobenzothiazole, N, N'-dicyclohexyl-
Vulcanization accelerators such as sulfenamides such as 2-benzothiazolylsulfenamide, thiurams such as tetramethylthiuram disulfide, and vulcanization accelerators such as zinc oxide;
Anti-aging agents such as poly (2,2,4-trimethyl-1,2-dihydroquinoline) and amines such as phenyl-α-naphthylamine.

Of these, fillers such as carbon black and silica are used as reinforcing agents for increasing the tensile strength, breaking strength, modulus, hardness, etc. of the vulcanized rubber, and improving the abrasion resistance and tensile resistance. It is known that zinc oxide forms a complex compound with a fatty acid, and is known as a vulcanization accelerator which enhances the vulcanization acceleration effect.

In the heat-resistant conveyor belt of the present invention, the adhesive rubber layer 2 contains 0.1 to 20 parts by weight of an organic peroxide and 0.1 to 0.1 parts by weight of a sulfur-based vulcanizing agent based on 100 parts by weight of a rubber component. It is preferable that the amount of the organic peroxide is 1 to 10 parts by weight, and the amount of the sulfur-based vulcanizing agent is 0.5 to 7 parts by weight. This is because when the organic peroxide is less than 0.1 parts by weight, the upper and lower cover rubbers 3
This is because there is a decrease in the adhesive performance due to thermal deterioration between the adhesive rubber layer 2 and the adhesive rubber layer 2, whereas when it exceeds 20 parts by weight, the physical properties of the adhesive rubber layer are reduced. In addition, the sulfur-based vulcanizing agent is 0.1%.
If the amount is less than 1 part by weight, sufficient vulcanization adhesion with the galvanized cord cannot be obtained, while if it exceeds 15 parts by weight, the physical properties of the adhesive rubber layer deteriorate. When the steel cord embedded in the adhesive rubber layer 2 is a galvanized steel cord, an organic acid cobalt can be blended as an adhesive between the galvanized steel cord and the rubber. As such an organic acid cobalt, for example, cobalt naphthenate, cobalt octylate, cobalt neodecanoate and the like are preferably used.

The rubber composition of the cover rubber 3 according to the present invention comprises ethylene-propylene rubber (EP) as a rubber component.
M) and an organic peroxide as a vulcanizing agent. As a result, a belt having excellent high-temperature heat resistance can be obtained. The compounding amount of this organic peroxide is preferably 1 to 10 parts by weight based on 100 parts by weight of the rubber component.

The heat-resistant conveyor belt according to the present invention is obtained, for example, by obtaining an unvulcanized rubber sheet from the above-mentioned rubber composition for the adhesive rubber layer and the cover rubber, and between the unvulcanized rubber sheet for the adhesive rubber layer. A steel cord is arranged at an appropriate pitch and sandwiched, and an unvulcanized rubber sheet for the cover rubber is sequentially laminated on both sides of these adhesive rubber sheets, and these are vulcanized and adhered according to a conventional method. Can be.

[0038]

Next, the present invention will be described with reference to examples. A rubber composition for an adhesive rubber layer and a rubber composition for an upper and lower cover rubber were prepared according to the content (parts by weight) shown in Tables 1 and 2 below. The steel cords used in Examples 1 to 4 and Comparative Example 1 were subjected to a galvanizing treatment.

[0039]

[Table 1] * 1: Manobond C2, manufactured by Rhone Bouland
2.5 (Cobalt boron neodecanoate (Co: 2
2.5%)) * 2: 1,3-bis (t-butylperoxyisopropyl) benzene (trade name: Peroximon F-40) manufactured by NOF Corporation

[0040]

[Table 2] * 3: EPM manufactured by Nippon Synthetic Rubber Co., Ltd. * 4: 1,3-bis (t-butylperoxyisopropyl) benzene (trade name: Peroximon F-40) manufactured by NOF Corporation

For each rubber composition, JIS K63
According to the peel test of "01-1975" Physical test method for vulcanized rubber ", the adhesive strength after accelerating the heat aging at 180 ° C for 7 days was measured before aging. The results obtained are shown in Table 3 below.

[0042]

[Table 3]

[0043]

As described above, in the present invention, a heat-resistant conveyor belt reinforced with a steel cord which has not been subjected to a plating treatment, and a steel cord which has been subjected to a galvanizing treatment, have also been provided. All of the heat-resistant conveyor belts have more excellent heat resistance than conventional products.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a heat-resistant conveyor belt according to an embodiment of the present invention.

[Explanation of symbols]

 1 Galvanized steel cord 2 Adhesive rubber layer 3 Cover rubber

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 21:00 23:00 105: 08 105: 24 F term (Reference) 3F024 AA07 CA01 CA04 CA08 CB03 CB10 CB13 4F213 AA09 AA45 AB03 AB18 AB19 AB22 AD03 AD15 AD18 WA03 WA33 WA39 WA87 WB01 WB11 WC01

Claims (7)

[Claims] 1. A heat-resistant conveyor belt comprising an adhesive rubber layer having a steel cord as a core body and a cover rubber vulcanized and bonded to the upper and lower surfaces of the adhesive rubber layer, wherein: An ethylene-propylene-diene rubber as a component, and b) an organic peroxide and a sulfur-based vulcanizing agent as a cross-linking agent are blended, and m) an ethylene-propylene rubber as a rubber component and n ) A heat-resistant conveyor belt comprising an organic peroxide as a vulcanizing agent. 2. A heat-resistant conveyor belt comprising an adhesive rubber layer having a galvanized steel cord as a core and a cover rubber vulcanized and bonded to the upper and lower surfaces of the adhesive rubber layer, wherein the adhesive rubber layer has a A) ethylene-propylene-diene rubber as a rubber component, b) an organic peroxide and a sulfur-based vulcanizing agent as a crosslinking agent, and c) Zn, K, Al, T
a metal salt of an organic acid containing at least one metal selected from the group consisting of i and Zr, and an adhesion promoter containing a hydrated inorganic salt; A heat-resistant conveyor belt comprising: (a) an ethylene / propylene rubber as a rubber component; and (n) an organic peroxide as a vulcanizing agent. 3. The rubber composition according to claim 1, wherein said adhesion promoter is 2.0 × 10 ^{−4 to} 2.0 × 10 ⁻² mol in terms of metal in a metal salt of an organic acid as the component. And 2.5 × 10 ⁻³ to 2.5 × in terms of water in the hydrous inorganic salt
The heat-resistant conveyor belt according to claim 2, wherein the amount is 10 ^-1 mol. 4. The heat resistant conveyor belt according to claim 2, wherein the adhesive rubber layer further contains d) an organic molybdenum compound. 5. The heat-resistant conveyor belt according to claim 2, wherein an organic molybdenum compound is contained in place of the hydrated inorganic salt in the component of the adhesion promoter of c). 6. The rubber composition according to claim 1, wherein said adhesion promoter is 2.0 × 10 ^{−4 to} 2.0 × 10 ⁻² mol in terms of metal in a metal salt of an organic acid as the component. And 2.0 × in terms of molybdenum in the organic molybdenum compound
The heat-resistant conveyor belt according to claim 5, wherein the amount is ^{10-6 to} 2.0 x 10 mol. 7. The rubber component 10 in the adhesive rubber layer.
0.1 to 20 parts by weight of the organic peroxide with respect to 0 parts by weight,
The heat-resistant conveyor belt according to any one of claims 1 to 6, further comprising 0.1 to 15 parts by weight of a sulfur-based vulcanizing agent.