WO2016021448A1 - Conveyor belt, method for producing conveyor belt, and rubber composition - Google Patents

Abstract

Provided is a conveyor belt in which a back-surface-side cover rubber layer is formed by a rubber composition including a diene-based rubber, carbon black, silica, and a silane coupling agent, wherein a sulfide-based silane coupling agent and an amino-based silane coupling agent are included as the silane coupling agent.

Description

Conveyor belt, conveyor belt manufacturing method, and rubber composition Cross-reference of related applications

This application claims the priority of Japanese Patent Application No. 2014-161050, and is incorporated herein by reference.

The present invention relates to a conveyor belt, a method for manufacturing a conveyor belt, and a rubber composition.

Conventionally, conveyor belts, which are the main components of belt conveyors widely used as conveying devices for articles and materials, are commercially available in various shapes and materials, and these are used properly according to the application. It has been.
In applications where high strength is generally required, a rubber conveyor belt is used. This rubber conveyor belt has a core at the center in the thickness direction, and the core is mounted on both the front and back sides. Those provided with a cover rubber layer covering from a wide range are widely used.
As a rubber composition constituting the cover rubber layer of this conveyor belt, a rubber composition having a base rubber made of diene rubber such as natural rubber or polybutadiene rubber is known because of its excellent strength and wear resistance (see below). (See Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 11-139523 Japanese Unexamined Patent Publication No. 2008-38133

A belt conveyor is usually provided with a conveyor belt in an endless state. This type of belt conveyor includes a driving pulley and a driven pulley for driving the conveyor belt over the belt.
In addition, the belt conveyor as described above usually includes a plurality of support rollers for supporting the conveyor belt from the back side between the driving pulley and the driven pulley.
The conveyor belt is not only greatly bent by the driving pulley and the driven pulley during operation, but also on the back side (non-conveying side) when passing over the support roller arranged between the driving pulley and the driven pulley. Deformation such as slight bending, stretching, and compression occurs.

Most of the rubber conveyor belt as described above is occupied by a cover rubber layer.
And since this cover rubber layer is provided in the conveyor belt in the form extended in a belt longitudinal direction, naturally, like the whole conveyor belt, a deformation | transformation will arise at the time of operation of a belt conveyor.
In general conveyor belts, tension is generated in the longitudinal direction of the belt by driving force or frictional force during operation of the belt conveyor. Further, a general conveyor belt is subjected to a compressive stress or the like when a conveyed product is loaded and passed over a support roller during operation of the belt conveyor.
In particular, as belt conveyors have become longer and faster in recent years, the proportion of energy loss that occurs when the conveyor belt passes over the support roller is increasing among the energy loss that occurs in the conveyor belt. .
The cover rubber on the back side that comes into contact with the support roller has a relatively high elastic modulus and is formed of a rubber composition having a low loss coefficient (Tan δ) in dynamic viscoelasticity. It is preferable from the viewpoint of suppressing energy loss when received.
That is, in order to make the conveyor belt exhibit energy saving, it is effective to form the back side cover rubber layer with a rubber composition having at least a relatively high elastic modulus of the back side cover rubber layer and a low loss coefficient. is there.
However, as in Patent Documents 1 and 2, when the loss coefficient (Tanδ) of the cover rubber is reduced, energy loss when passing over the support roller is reduced, and power consumption when driving the conveyor belt is reduced. However, the durability of the cover rubber, such as tear resistance and wear resistance, tends to be low.
Thus, the conventional conveyor belt has a problem that energy saving and durability cannot be achieved at the same time.

The present invention has been made paying attention to such points, and provides a rubber composition having a low loss factor while maintaining basic physical properties such as tensile strength and tear strength, and thus, energy saving and durability. It is an object to provide a conveyor belt having a good balance of performance.

In order to solve the above problems, the present invention is a conveyor belt provided with a front side cover rubber layer and a back side cover rubber layer as a cover rubber layer extending along the longitudinal direction of the belt, and at least the back side cover The rubber composition constituting the rubber layer contains a diene rubber, carbon black, silica, and a silane coupling agent, and a sulfide silane coupling agent and an amino silane coupling agent as the silane coupling agent. Conveyor belt including is provided.

Moreover, this invention is a conveyor belt manufacturing method which produces the conveyor belt provided with the surface side cover rubber layer and the back side cover rubber layer as a cover rubber layer extended along a belt longitudinal direction in order to solve the said subject. A rubber composition comprising a diene rubber, carbon black, silica, and a silane coupling agent, and a sulfide silane coupling agent and an amino silane coupling agent as the silane coupling agent is prepared. Conveyor belt for carrying out a first step, a second step of forming at least the back side cover rubber layer with the rubber composition produced in the first step among the front side cover rubber layer and the back side cover rubber layer A manufacturing method is provided.

Furthermore, the present invention includes a diene rubber, carbon black, silica, and a silane coupling agent in order to solve the above-mentioned problems, and as the silane coupling agent, a sulfide silane coupling agent and an amino silane. A rubber composition comprising a coupling agent is provided.

According to the present invention, a rubber composition having a low loss factor can be provided while maintaining basic physical properties such as tensile strength and tear strength.
Therefore, according to the present invention, a conveyor belt excellent in energy saving and durability can be provided.

The general use state figure of the belt conveyor provided with the conveyor belt of one embodiment. FIG. 2 is a cross-sectional view taken along the line II of FIG. 1 showing a schematic cross-sectional structure of the conveyor belt of one embodiment. The schematic perspective view of the belt conveyor with which the conveyor belt was provided in the aspect different from FIG. FIG. 4 is a cross-sectional view taken along line II-II in FIG. 3.

Embodiments of the present invention will be described below.
In the following, embodiments of the present invention will be described by taking as an example the case where the rubber composition of the present invention is a rubber composition for conveyor belts and the rubber composition is used for forming cover rubber.
First, a belt conveyor using the conveyor belt of this embodiment will be described with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing a method of using a belt conveyor provided with the conveyor belt of the present embodiment, and FIG. 2 is a cross-sectional structure taken along a line II shown in FIG. It is arrow sectional drawing which showed schematically.

FIG. 1 shows a state of the belt conveyor 1 in which the conveyor belt 10 of the present embodiment formed in an endless shape is arranged so as to have a constant upward gradient from the right side to the left side when viewed from the front in FIG. . FIG. 1 shows a state in which the transported object A is transported as viewed from the side in the transport direction.
In the belt conveyor 1 of this embodiment, the conveyor belt 10 is stretched between pulleys 20 arranged on one end side (loading side) and the other end side (unloading side) in the longitudinal direction of the transport path. .
Of the pair of pulleys 20 around which the conveyor belt 10 is stretched, the unloading pulley 20 is a driving pulley 21 connected to a driving source. The pulley 20 arranged on the stacking side is a driven pulley 22 that rotates together with the endless conveyor belt 10 circulated by the drive pulley 21.

In the belt conveyor 1 of this embodiment, support rollers 30 are arranged at a plurality of locations between the drive pulley 21 and the driven pulley 22. The belt conveyor 1 of the present embodiment is provided with a plurality of forward path side support rollers 30a that support the conveyor belt 10 from the back surface side in a transport path (forward path) from the stacking side to the unloading side. The belt conveyor 1 includes a plurality of return-side support rollers 30b that come into contact with the surface of the conveyor belt 10 facing downward in a path (return path) from the unloading side to the loading side. ing. The return path side support roller 30b supports the conveyor belt by bringing the outer peripheral surface into contact with the surface of the conveyor belt 10.

That is, the driving pulley 21, the driven pulley 22, and the plurality of forward path side support rollers 30a are arranged with their rotation axes arranged in parallel to each other so that the conveyor belt 10 in the forward path can be supported at a substantially constant inclination. Is provided on the belt conveyor 1 so that the vertical position of FIG.
Further, the plurality of the return path side support rollers 30b are arranged in parallel with each other so that the conveyor belt 10 on the return path can be supported at a substantially constant inclination, and the vertical position of the upper end portion is lowered to the right in FIG. It is provided in the belt conveyor 1 so as to be.

In addition, the conveyor belt 10 in this embodiment is formed in the shape of a flat belt which is not provided with a horizontal beam crossing in the belt width direction and an ear beam standing along both side edges of the belt.
As shown in FIG. 2, the conveyor belt 10 in the present embodiment has a cover rubber 11 (hereinafter referred to as “surface side cover rubber 11a”) that forms the surface side (outer peripheral side) of the conveyor belt 10 on which the conveyed product A is placed. And a cover rubber 11 constituting a back surface opposite to the surface on which the conveyed product A is placed (hereinafter also referred to as “back surface cover rubber 11b”). ing. In the conveyor belt 10 in this embodiment, a core body layer 12 is formed inside the two layers of cover rubber 11. The core body layer 12 is formed by embedding a core canvas for imparting a tensile strength to the conveyor belt inside the cover rubber 11 of two layers.
That is, the front surface side cover rubber 11a and the back surface side cover rubber 11b form a rubber layer extending along the longitudinal direction of the belt, and are formed to have a substantially constant thickness in the longitudinal direction of the belt.

In the belt conveyor 1 of the present embodiment, when the conveyed product A is positioned between the forward path side support rollers 30a, the conveyor belt 10 is bent downward due to the weight of the conveyed product A during operation. Become.
That is, in a situation where the weight of the conveyed product A is not supported by the forward path side support roller 30a, a tension corresponding to the weight of the conveyed product A is applied to the conveyor belt 10.
In the belt conveyor of the present embodiment, the conveyor belt 10 is lifted as the conveyed product A approaches the forward path support roller 30a, and after the conveyed object A passes the forward path support roller 30a, the forward path side. As the distance from the support roller 30a increases, the conveyor belt 10 is bent downward again.
In this way, the conveyor belt 10 according to the present embodiment undergoes multiple bendings in the outward path.
As shown in FIG. 2, the belt conveyor 1 of the present embodiment has a plurality of forward path support rollers 30 a arranged in the belt width direction at locations where the conveyor belt 10 is supported by the forward path support rollers 30 a.
And the belt conveyor 1 of this embodiment makes the state which lifted the width direction both ends of the conveyor belt 10 rather than the center part with these some outward path side support rollers 30a, made the conveyor belt 10 into a bowl shape, and the conveyed product A became The falling from the side of the conveyor belt 10 is prevented.
That is, the conveyor belt 10 of the present embodiment is bent into a bowl shape after passing through the driven pulley 22 in a flat state, and returned to a flat state before being wound around the drive pulley 21.
Further, the conveyor belt 10 is greatly bent by these when passing through the driving pulley 21 and the driven pulley 22.
Furthermore, the conveyor belt 10 of the present embodiment applies a compressive stress or the like by the forward support roller 30a and the transported object A due to the mass of the transported object A when the transported object A passes over the forward support roller 30a. It is done.

Because of the above, at least the back side cover rubber 11b out of the front side cover rubber 11a and the back side cover rubber 11b has a relatively high elastic modulus and a cycle of “elastic deformation-restoration”. It is preferable that hysteresis loss is small. The back-side cover rubber 11b is preferably composed of a rubber composition having a low dynamic loss factor (Tan δ).
The conveyor belt of this embodiment can form the said surface side cover rubber | gum 11a with the rubber composition similar to the back surface side cover rubber | gum 11b illustrated below.
The front side cover rubber 11a and the back side cover rubber 11b do not need to be formed of the same rubber composition, and may be formed of different rubber compositions.

The rubber composition for conveyor belts of this embodiment used for forming the back side cover rubber 11b includes components such as a base rubber, a filler, and an additive. Specifically, a diene rubber, carbon black, Silica and a silane coupling agent are included.
Further, the rubber composition of the present embodiment includes a sulfide-based silane coupling agent and an amino-based silane coupling agent as a silane coupling agent.

The rubber composition preferably contains natural rubber and a diene rubber other than natural rubber as a rubber component. From the viewpoint of reducing the loss coefficient (Tanδ) at low temperatures of the rubber composition, polybutadiene other than natural rubber is used. It preferably contains rubber or styrene-butadiene rubber.
The rubber composition has a functional group capable of binding to a filler (filler) in the molecule as the polybutadiene rubber or the styrene-butadiene rubber, particularly from the viewpoint of achieving both a loss factor (Tan δ) and tear strength. It is preferable to contain a modified product prepared at the end of the main chain.
It is preferable that the rubber composition contains natural rubber at a ratio of 50 mass% to 80 mass% in the rubber component.
Therefore, when the rubber composition contains a modified product and / or a non-modified product of polybutadiene rubber or styrene-butadiene rubber, the total of all polybutadiene rubbers and all styrene-butadiene rubbers is 20% by mass in the rubber component. The content is preferably 50% by mass or less.

The rubber composition may contain a filler other than the carbon black and the silica. Examples of the filler other than the carbon black and the silica include talc, clay, calcium carbonate, and aluminum hydroxide. Can be mentioned.
However, in the present embodiment, it is not preferable to contain a filler other than carbon black and silica in the rubber composition.
Accordingly, the filler contained in the rubber composition is preferably 80% by mass or more of carbon black and silica, more preferably 90% by mass or more of carbon black and silica, and 95% by mass or more of carbon. Particularly preferred are black and silica.

While the carbon black is an effective component for exerting strength against the cover rubber, the carbon black tends to form an agglomerate by itself in the cover rubber.
This agglomerate collapses when a large deformation occurs in the cover rubber, and the shear elastic modulus decreases, which may increase the hysteresis loss of the cover rubber.
For this reason, in this embodiment, the rubber composition contains silica, which generally has a tendency to be inferior to carbon black in terms of reinforcing effect, but can make it difficult to form agglomerates with a silane coupling agent or the like. ing.
Specifically, the content of silica contained in the rubber composition is preferably 5 to 60 parts by mass and more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the diene rubber. .
Moreover, it is preferable that the ratio of the silica to the sum total of carbon black and a silica is 25 to 75 mass%.

As carbon black for reinforcing rubber, those classified as HAF, FEF and the like in ASTM D 1765 are widely used. However, in this embodiment, the rubber composition has a low loss factor. Therefore, it is preferable to employ carbon black having a relatively large particle size classified as GPF or SRF in the same standard.
More specifically, in the rubber composition of the present embodiment, 80% by mass or more of the carbon black contained is preferably GPF or SRF, and more preferably 90% by mass or more is GPF or SRF. 95% by mass or more is particularly preferably GPF or SRF.

The silica in the present embodiment preferably has a particle size of a certain size or more, like carbon black.
The silica is preferably produced by a wet method rather than the one produced by a dry method, and among the wet methods, one produced by a sedimentation method is more preferred than that produced by a gel method.
More specifically, the silica contained in the rubber composition of the present embodiment is preferably one in which primary particles having a size of 10 nm to 50 nm are aggregated to form secondary particles, and an average of 1 μm to 40 μm. What has a particle diameter is preferable. In the present embodiment, silica having a BET specific surface area of 20 m ² / g to 400 m ² / g is preferable.

In addition, also about this silica, secondary particles may form an aggregate.
Such agglomerates of silica may deteriorate the loss factor of the rubber composition in the same manner as the agglomerates of carbon black.
Therefore, the rubber composition of this embodiment contains an amino-based silane coupling agent and a sulfide-based silane coupling agent for the purpose of improving the dispersibility of silica in the rubber composition.
The amino silane coupling agent and the sulfide silane coupling agent do not need to be contained alone in the rubber composition, and two or more of them may be contained in the rubber composition.

Examples of the amino-based silane coupling agent include 3-aminopropyltrimethoxysilane (γ-aminopropyltrimethoxysilane), N-3- (4- (3-aminopropoxy) butoxy) propyl-3-aminopropyl Trimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (N-β (aminoethyl) γ-aminopropyltri Methoxysilane), N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine and its partial hydrolyzate, N-phenyl -3-aminopropyltrimethoxysilane), N- (vinylbenzyl) -2-aminoe Le-3-aminopropyl hydrochloride trimethoxysilane and the like.
The amino silane coupling agent contained in the rubber composition of this embodiment is preferably 3-aminopropyltrimethoxysilane.
The rubber composition of the present embodiment prevents the influence of the addition of the amino-based silane coupling agent from being excessively manifested in the viscoelasticity of the rubber composition, and improves the work such as rubber kneading. It is preferable to use an alkylamine together with an amino silane coupling agent. The alkylamine has an alkyl group having 6 to 20 carbon atoms, and is preferably either a monoalkylamine having one alkyl group or a dialkylamine having two alkyl groups. . The alkylamine is preferably a monoalkylamine such as octylamine or dodecylamine.

Examples of the sulfide silane coupling agent include a monosulfide silane coupling agent and a polysulfide silane coupling agent.
As the sulfide-based silane coupling agent contained in the rubber composition of the present embodiment, a polysulfide-based silane coupling agent such as bis (3-triethoxysilylpropyl) tetrasulfide is preferable.

The amino silane coupling agent and the alkylamine are effective components for improving the hardness of the rubber composition.
Therefore, the compound containing all the components contained in the rubber composition contains the amino-based silane coupling agent and the alkylamine even when an aggregate formed by the silica or the carbon black is formed during kneading. Shear force is easily applied to the agglomerates.
That is, the rubber composition contains the amino-based silane coupling agent and the alkylamine, thereby reducing the abundance of aggregates due to the silica and the carbon black.
On the other hand, the work of kneading these blends, when the amino silane coupling agent and the alkylamine are excessively blended, decreases the efficiency, for example, the time until obtaining a uniform blend is prolonged. There is a case.
Accordingly, the content of the amino silane coupling agent with respect to 100 parts by mass of the silica is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and 3 parts by mass or more. It is particularly preferred.
The content of the amino silane coupling agent with respect to 100 parts by mass of silica is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less.

The content of the alkylamine with respect to 100 parts by mass of the silica is preferably 1 part by mass or more, and more preferably 1.5 parts by mass or more.
The content of the alkylamine with respect to 100 parts by mass of the silica is preferably 10 parts by mass or less, and more preferably 7 parts by mass or less.

In the rubber composition, the content of the amino silane coupling agent with respect to 100 parts by mass of silica is “Xa (parts by mass)”, and the content of the alkylamine with respect to 100 parts by mass of silica Is preferably “Xb (parts by mass)”, it is preferable to satisfy all of the following relational expressions (1) to (3).

3 ≦ Xa ≦ 10 (1)
1 ≦ Xb ≦ 7 (2)
4 ≦ (Xa + Xb) ≦ 14 (3)

In the rubber composition of the present embodiment, the content of the sulfide-based silane coupling agent with respect to 100 parts by mass of the silica is preferably 1 part by mass or more and 20 parts by mass or less, and is 5 parts by mass or more and 15 parts by mass or less. It is preferable.

These silane coupling agents are effective for imparting affinity between rubber components such as natural rubber and silica particles.
As will be described later, in order to make the rubber composition have a low loss coefficient, silica is coupled with a sulfide-based silane coupling agent after being coupled with an amino-based silane coupling agent. Is preferably applied.

That is, it is preferable that the coupling treatment with the sulfide-based silane coupling agent is performed after the coupling treatment with the amino-based silane coupling agent. Although it can be easily dispersed in the components, it is thought that the aggregates covered with the coupling agent are formed and the silica forming the aggregates is difficult to be dispersed individually.
In other words, the coupling treatment with the amino silane coupling agent is preferably performed prior to the coupling treatment with the sulfide silane coupling agent. In this case, the agglomerates covered with the coupling agent are formed in common, but it is considered that the agglomerates are easily crushed by being sheared by kneading. In addition, silica that has been crushed into individual particles having at least a part of the surface subjected to coupling treatment is usually subjected to coupling treatment with a sulfide-based silane coupling agent, thereby suppressing reaggregation, Dispersibility becomes even better.

The rubber composition of this embodiment can contain additives other than the silane coupling agent.
Examples of the additive include vulcanizing agents such as sulfur and organic peroxides; aldehyde / ammonia compounds, guanidine compounds, thiourea compounds, thiazole compounds, sulfenamide compounds, thiuram compounds, dithiocarbamates Vulcanization accelerators such as organic compounds; vulcanization retarders such as organic acids, nitroso compounds, halides, 2-mercaptobenzimidazole, N-cyclohexylthiophthalimide; amino / ketone compounds, aromatic amine compounds, monophenols Anti-aging agents such as compounds, polyphenol compounds and benzimidazole compounds; processing aids such as fatty acid ester compounds; flame retardants and pigments.

The conveyor belt of the present embodiment is not particularly limited with respect to the core for forming the core body layer 12, and a conveyor belt used for a general conveyor belt can also be employed in this embodiment. .
In the present embodiment, a canvas or the like is exemplified as the core body, but the core body does not have to be a canvas and may be a steel cord or the like.

The manufacturing method of the conveyor belt of this embodiment is not particularly limited, and can be manufactured in the same manner as a general conveyor belt.
The method for producing a conveyor belt according to the present embodiment includes a cover rubber layer extending along the belt longitudinal direction, and the front rubber cover layer and the rear cover rubber layer as the cover rubber layer. And a second step of forming at least the back side cover rubber layer of the front side cover rubber layer and the back side cover rubber layer with the rubber composition produced in the first step. The method of implementing is mentioned.
The first step includes a diene rubber, carbon black, silica, and a silane coupling agent. The rubber includes a sulfide silane coupling agent and an amino silane coupling agent as the silane coupling agent. The composition may be prepared by a general method.
The rubber composition can be produced, for example, by kneading a compound containing all components using a Banbury mixer, a kneader mixer, a roll, or the like. The conveyor belt is manufactured by forming an unvulcanized sheet for a cover rubber by molding a rubber composition into a sheet shape using a calendar or the like, and vulcanizing the unvulcanized sheet and canvas integrally. be able to.

More specifically, a rubberized canvas is prepared, and the canvas is sandwiched between unvulcanized sheets for cover rubber, and “unvulcanized sheet for front side cover rubber / canvas / unvulcanized sheet for back side cover rubber”. The above-mentioned conveyor belt can be produced by forming a laminated body laminated in the order of “” and integrating the laminated body while vulcanizing using a vulcanizing press.

In the present embodiment, as described above, it is preferable that the silica is subjected to the coupling treatment with the sulfide-based silane coupling agent after the coupling treatment with the amino-based silane coupling agent.
Therefore, in the rubber kneading for producing the unvulcanized rubber sheet, silica previously coupled with an amino silane coupling agent is used, and a sulfide silane coupling agent is added during the rubber kneading. Alternatively, the addition of the silane coupling agent is preferably carried out in two steps.

That is, in the first step, the first kneading is performed by kneading the first compound in which one or more components among all the components contained in the rubber composition are insufficient, and the first kneading. Second kneading the second compound containing the kneaded product and the second compound supplemented with the lacking component, the amino compound containing an amino-based silane coupling agent, and The first kneading is performed in a state where the sulfide-based silane coupling agent is deficient in the first compound, and the second compound supplemented with the sulfide-based silane coupling agent is kneaded in the second compounding. It is preferable to prepare a rubber composition.
Here, “the component is insufficient” means not only the case where “the component is included but the proportion thereof is small”, but also the case where “the component is not included”.
In the first kneading, it is preferable that a sulfide-based silane coupling agent is not substantially contained in the first compound.

Note that the silane coupling agent is preferably sufficiently reacted with silica.
Accordingly, the kneading of the rubber composition is preferably carried out in a heated state (for example, 100 ° C. or higher) in the sense of reacting silica and the silane coupling agent.
On the other hand, when the rubber composition is kneaded in a heated state, the double bond of the rubber is excessively cut or the vulcanization proceeds, so that the desired properties are exhibited in the cover rubber. There is a risk that it will be difficult.
In particular, the kneading of the rubber composition including the vulcanizing agent is preferably performed at a temperature lower than 100 ° C, and preferably performed at a temperature lower than 80 ° C.
Therefore, when producing the rubber composition, the first compound containing the amino silane coupling agent without substantially containing the vulcanizing agent or the sulfide silane coupling agent is kneaded at a temperature of 100 ° C. or higher. A step, a step of cooling the kneaded product to a temperature of less than 100 ° C. after the step, a step of adding a sulfide-based silane coupling agent after the step and kneading at a temperature of 100 ° C. or more, and a kneaded product after the step of 100 It is preferable to carry out at least the step of cooling to a temperature of less than 0 ° C. and the step of kneading at a temperature of less than 100 ° C. after containing the vulcanizing agent.

Further, in the present embodiment, since it is formed of a rubber composition having a low loss coefficient while maintaining the basic physical properties of the cover rubber, energy loss is unlikely to occur when passing over the support roller, and tensile strength. In addition, a decrease in tear strength and the like can be suppressed.
Therefore, the belt conveyor is excellent in energy saving and durability by being provided with the conveyor belt of this embodiment.

In addition, in this embodiment, since it is advantageous in exhibiting the effect of the present invention more remarkably, the conveyor belt 10 is used in the form of a bowl curved in the width direction when transporting the transported object A, The case where bending in the width direction as well as the longitudinal direction is performed at the time of use is illustrated.
However, the effect of the present invention is also exhibited in a conveyor belt that is only bent in the longitudinal direction during use.
Further, as shown in FIGS. 3 and 4, examples in which the bending of the width direction is larger than that of the conveyor belt shown in FIGS.

3 and 4 show a belt conveyor 1 called a pipe conveyor and the use state of the conveyor belt 10 in the belt conveyor 1.
The conveyor belt 10 shown in FIGS. 3 and 4 is common to the conveyor belt shown in FIGS. 1 and 2 in that it is endless and is stretched between the drive pulley 21 and the driven pulley 22.
The conveyor belt 10 shown in FIGS. 3 and 4 is also common to the conveyor belt shown in FIGS. 1 and 2 in that the conveyor belt 10 is distorted when getting over the forward path side support roller 30a and the backward path side support roller 30b.
The conveyor belt 10 shown in FIGS. 3 and 4 is also shown in FIGS. 1 and 2 in that a core layer (not shown) is formed between the front cover rubber 11a and the back cover rubber 11b. Common to the conveyor belt shown.
On the other hand, the conveyor belt 10 shown in FIGS. 3 and 4 is used in a state in which the conveyor belt 10 is rolled into a cylindrical shape in a section where the conveyed product A is conveyed.
That is, the conveyor belt 10 shown in FIGS. 3 and 4 has both ends in the width direction lifted by the forward-side support rollers 30a after the conveyed product A is placed on the upper surface of the front-side cover rubber 11a on the stacking side. The lifted both end portions are drawn so that the back side faces upward, and the both end portions are overlapped to form a cylindrical shape, and this cylindrical state is maintained until unloading.

Because of the above, the belt conveyor 1 shown in FIGS. 3 and 4 is suitable for transporting a transported object A or the like which is easily scattered such as powder, and is large for the conveyor belt 10 when it is formed into a cylindrical shape. Since distortion is added, the effect of the present invention becomes more remarkable.
In particular, even if a part of the conveyed product A adheres to the surface of the surface side cover rubber 11a, the conveyor belt 10 is formed into a cylinder by the return side support roller 30b in the return path so that it does not fall on the return path. In the belt conveyor 1 of the shape, the effect of the present invention is particularly remarkable.
As described above, the effects of the present invention are exhibited in various conveyor belts other than those shown in FIGS.

Such an effect does not occur only when the rubber composition of the present embodiment is used as a cover rubber.
For example, in a conveyor belt or the like having ear rails erected along both sides of the belt, energy loss during traveling can be reduced by forming the ear rails with the rubber composition of the present embodiment. .
The rubber composition for conveyor belts of the present invention can be applied not only to the back cover rubber layer, but also to the front cover rubber layer and the core layer, and is useful for forming other parts of the conveyor belt. It is a thing.

Further, the rubber composition of the present embodiment is a compressed rubber layer of a V belt or V ribbed belt that is used by being wound around a pulley with a V groove, a tooth portion of a toothed belt that is used by being wound around a toothed pulley, or the like. It is also useful for the formation of
Furthermore, the rubber composition of this embodiment is useful as a material for forming a transmission belt such as a round belt or a flat belt.
The rubber composition of the present embodiment is not only useful as a rubber composition for belts such as conveyor belts and transmission belts, but also can be used in various applications that require both energy saving and durability.

The rubber composition and conveyor belt of the present invention are not limited to the above examples.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

(Evaluation 1)
(Example 1)
Natural rubber (NR) (trade name: SVRCV60 DAU TIENG RUBBER CORPORION) and polybutadiene rubber (BR) (trade name: VCR-412 manufactured by Utsuko) at a ratio of 60/40 (NR / BR) Banbury mixer (trade name) : Mixtron BB180 manufactured by Kobe Steel Co., Ltd., and there are 12 parts by mass of carbon black (GPF) (trade name: made by SEAST V Tokai Carbon) as a filler. And silica (precipitated silica) (trade name: Ultrasil VN3, manufactured by Evonik Degussa Japan), 30 parts by mass, and then an amino silane coupling agent (3-aminopropyltriethoxysilane) (trade name: dynasilane AMEO). Evonik Degussajapa 1.3 parts by mass and 0.7 parts by mass of octylamine (trade name: Farmin 08D manufactured by Kao) were added and reacted at 150 ° C., and then a sulfide-based silane coupling agent (bis (3-tri Ethoxysilylpropyl) tetrasulfide) (trade name: Si69 manufactured by Evonik Degussa Japan) (3 parts by mass) was added and reacted at 140 ° C.
Finally, as processing aids, stearic acid (trade name: bead stearic acid Tsubaki Sanyu Industrial, (processing aid 1)) and three types of zinc oxide (trade name: Zinc Hana 3A, made by Mitsui Mining & Mining, Auxiliary agent 2)), anti-aging agent (trade names: Nocrack 6C, Nocrack 224, Sunnock, and Nocrack AW-N Ouchi Shinsei Chemical), Vulcanization accelerator (Product No .: Noxeller NS-F Ouchi Shinsei Chemical) ), A vulcanization retarder (trade name: MIRAD PVI, manufactured by Ogura Sandine Co., Ltd.), and kneaded with a Banbury mixer.
The rubber after kneading is made into a sheet shape with a sheet extruder (trade name: TSR Kobe Steel), and then a vulcanizing agent (sulfur) (trade name: Seimi OT Rubber Industrial Materials) is charged in a mill blender. An unvulcanized rubber sheet having a predetermined thickness was obtained.

The vulcanized rubber sheet obtained by hot pressing this unvulcanized rubber sheet was evaluated according to the following items.

<Tensile test: Tensile strength, elongation at break>
The test conformed to JISK 6251 (2004) "Vulcanized rubber and thermoplastic rubber-Determination of tensile properties". The test piece was a JIS No. 3 dumbbell-shaped test piece with a thickness of 2.0 mm.

<Tear strength test>
As a testing machine, a tensile testing machine TS-1552 (trade name) manufactured by Ueshima Seisakusho Co., Ltd. was used. The test was based on JISK 6252 (2001) "Vulcanized rubber and plastic rubber-Determination of tear strength".
The test piece was a crescent-type test piece with a thickness of 2.0 mm.
The tearing force (TR) was determined by the following formula.

TR = F / t

TR: Tear force [N / mm]
F: Maximum tear force [N]
t: Test specimen thickness [mm]

<Hardness>
The hardness (instantaneous value) at normal temperature (23 ° C.) was measured with a type A durometer specified in JIS K 6253.

<Shear modulus>
As a testing machine, “RPA2000” manufactured by Alpha Technologies was used. The test conditions were a frequency of 0.5 Hz and a temperature of 40 ° C., the shear modulus at shear strain of 0.28% and 60% was measured, respectively, and the retention rate (%) of the shear modulus was obtained from the ratio thereof.
The test piece was produced by punching a disk having a diameter of 30 mm from a sheet having a thickness of 12.5 mm in accordance with JISK6300-2 (2001) “How to obtain vulcanization characteristics using a vibration vulcanization tester”.

<Test of loss factor (tan δ)>
As a testing machine, “FT-RheoSpectra DVE-V4” manufactured by Rheology Co., Ltd. was used. The test conditions were a frequency of 10 Hz, a temperature of 0 ° C., 20 ° C., a sample thickness of 1.0 mm, a sample length of 8.00 mm, and a sample width of 3 mm. The measured value of the loss factor tan δ was measured by applying a distortion of amplitude ± 2% in a state where the loss factor tan δ was extended by 5% with respect to the sample length.

(Other examples, comparative examples)
A rubber composition was prepared in the same manner as in Example 1 except that the rubber composition was prepared by the formulation shown in Table 1, and evaluation of the vulcanized rubber sheet was performed in the same manner as in Example 1.
In Example 5, silica (Product No .: Cupsil 8113 Evonik Degussa) that was previously surface-treated on silica (Product No .: Ultrasil VN3) with a sulfide-based silane coupling agent (Product No .: Si69) manufactured by Evonik Degussa Japan. A rubber composition was prepared by omitting the portion corresponding to the step of kneading the sulfide-based silane coupling agent in Example 1 because Si69 / VN3 = 13/87) manufactured by Japan was used.
In Comparative Example, a rubber composition was prepared by adding a sulfide-based silane coupling agent at the timing of adding the amino-based silane coupling agent in Example 1.
In Example 2 and Comparative Example 2, a rubber composition was prepared using styrene-butadiene rubber (SBR) (product number: NS616 manufactured by Nippon Zeon Co., Ltd.) instead of polybutadiene rubber (BR).
These evaluation results are also shown in Table 1 as in Example 1.

(Evaluation 2)
(Preparation of reference sample: Example 6)
Natural rubber (NR) (trade name: SVRCV60 DAU TIENG RUBBER CORPORION) and polybutadiene rubber (BR) (trade name: VCR-412 manufactured by Utsuko) at a ratio of 60/40 (NR / BR) Banbury mixer (trade name) : Mixtron BB180 manufactured by Kobe Steel Co., Ltd., and 12 parts by mass of carbon black (GPF) (product number: SEAST V manufactured by Tokai Carbon Co., Ltd.) as a filler (“mass part” is a ratio with respect to 100 parts by mass of rubber. Same as above) and silica (precipitated silica) (product number: Ultrasil VN3 manufactured by Evonik Degussa Japan), 30 parts by mass, and then an amino-based silane coupling agent (3-aminopropyltriethoxysilane) (trade name: dynasilane AMEO Evonik Degussa) Made in Japan After adding 2.5 parts by mass of the mixture and reacting at 150 ° C., 3 parts by mass of a sulfide-based silane coupling agent (bis (3-triethoxysilylpropyl) tetrasulfide) (product number: Si69 made by Evonik Degussa Japan) was added. In addition, the reaction was carried out at 140 ° C.
Finally, as processing aids, stearic acid (trade name: bead stearic acid made by Tsubaki Sanyu Industrial, (processing aid 1)) and three types of zinc oxide (product number: Zinc Hua 3A, made by Mitsui Mining & Mining, Agent 2)), anti-aging agent (trade names: Nocrack 6C, Nocrack 224, Sunnock, and Nocrack AW-N Ouchi Shinsei Chemical), vulcanization accelerator (trade name: Noxeller NS-F Ouchi Shinsei Chemical) ), A vulcanization retarder (trade name: MIRAD PVI, manufactured by Ogura Sandine Co., Ltd.), and kneaded with a Banbury mixer.
The rubber after kneading is made into a sheet shape with a sheet extruder (trade name: TSR Kobe Steel), and then a vulcanizing agent (sulfur) (trade name: Seimi OT Rubber Industrial Materials) is charged in a mill blender. An unvulcanized rubber sheet having a predetermined thickness was obtained.

Here, it was necessary to start the kneading of natural rubber and polybutadiene rubber with a Banbury mixer, and finally add the vulcanizing agent (sulfur) to uniformly disperse the vulcanizing agent (sulfur). The time was measured as “kneading time (T1)”.
And the thickness and width of the sheet | seat which disperse | distributed the vulcanizing agent are adjusted, The time until the said adjustment is completed and the unvulcanized rubber sheet which has desired thickness and width is obtained "rolling time (T2) Was measured.

Further, using a vulcanized rubber sheet obtained by hot pressing this unvulcanized rubber sheet, the shear modulus retention rate (60% / 0.3%) and 20 ° C. in the same manner as in “Evaluation 1”. Loss factor (tan δ) was measured.
The value of “shear modulus retention (%)” obtained here is an index representing the dispersibility of the filler.
Therefore, the value of “shear modulus retention (%)” of this reference sample was set as “dispersion index (D1)”.
Furthermore, the value of “loss factor (tan δ)” obtained here is an index representing energy saving.
Therefore, the value of “loss factor (tan δ)” of this reference sample was set as “energy saving index (S1)”.

(Production and determination of comparative sample (Example 6-12, Comparative example 5))
Next, a rubber sheet serving as a comparative sample with a blending content shown in Table 2 and a blending content different from that of the reference sample (Example 6) was produced.
Then, “kneading time (Tx)” and “rolling time (Ty)” in the production of this comparative sample were measured.
The percentage value [100% × (T1 / Tx)] obtained by dividing the “kneading time (T1)” of the reference sample by the “kneading time (Tx)” of this comparative sample is expressed as “workability during kneading”. It was used as an index for judgment.
Further, the percentage value [100% × (T2 / Ty)] obtained by dividing the “rolling time (T2)” of the reference sample by the “rolling time (Ty)” of the comparative sample is “workability during rolling”. It was used as an index for judging.
Both indicators were set so that the comparative sample had better workability, and the values were higher as the “kneading time (Tx)” and “rolling time (Ty)” were shorter.

Furthermore, the “dispersion index (Dx)” and “energy saving index (Sx)” of the comparative sample are obtained,
The percentage value [100% × (Dx / D1)] obtained by dividing the “dispersion index (Dx)” of this comparative sample by the “dispersion index (D1)” of the reference sample is judged as “filler dispersibility”. It was used as an indicator.
In addition, the percentage value [100% × (S1 / Sx)] obtained by dividing the “energy saving index (S1)” of the reference sample by the “energy saving index (Sx)” of the comparative sample is judged as “energy saving”. It was used as an indicator.
Here, the “dispersion index” is different from the “energy saving index”, “kneading time”, and “rolling time”, and the higher the value, the better the result.
Therefore, only the “dispersion index” is obtained by dividing the result of the comparative sample by the result of the reference sample.
In other words, both the “dispersibility of filler” and the “energy saving” index have higher values as good results are obtained as in “workability during kneading” and “workability during rolling”. Set.
These results are shown in Table 2.

Also from this result, according to the present invention, a rubber composition having a low loss factor can be obtained while maintaining basic physical properties such as tensile strength and tear strength, and a conveyor belt excellent in energy saving and durability can be obtained. I understand that
Moreover, from the above results, it can be seen that it is preferable to perform a coupling treatment with a sulfide-based silane coupling agent after performing an amino-based silane coupling treatment on silica.

In addition, from the above results, it is easy to manufacture a conveyor belt excellent in energy saving by adjusting the content of the amino silane coupling agent and the content of the alkylamine within a predetermined range with respect to the silica content. It can be seen that this is advantageous.

1: belt conveyor, 10: conveyor belt, 11: cover rubber, 12: core layer, 20: pulley, 30: support roller

Claims (7)

1. A conveyor belt provided with a front cover rubber layer and a back cover rubber layer as a cover rubber layer extending along the longitudinal direction of the belt,
   The rubber composition constituting at least the back side cover rubber layer includes a diene rubber, carbon black, silica, and a silane coupling agent, and a sulfide silane coupling agent and an amino system as the silane coupling agent. Conveyor belt containing silane coupling agent.
2. The rubber composition further comprises an alkylamine;
   The alkylamine has an alkyl group having 6 to 20 carbon atoms, and is either a monoalkylamine having one alkyl group or a dialkylamine having two alkyl groups. The conveyor belt described.
3. The rubber composition is
   The content of the amino silane coupling agent with respect to 100 parts by mass of silica is Xa parts by mass,
   The conveyor belt according to claim 2, wherein when the content of the alkylamine with respect to 100 parts by mass of silica is Xb parts by mass, all of the following formulas (1) to (3) are satisfied.
   
   3 ≦ Xa ≦ 10 (1)
   1 ≦ Xb ≦ 7 (2)
   4 ≦ (Xa + Xb) ≦ 14 (3)
4. A conveyor belt manufacturing method for producing a conveyor belt provided with a front side cover rubber layer and a back side cover rubber layer as a cover rubber layer extending along the belt longitudinal direction,
   A first step of producing a rubber composition containing a diene rubber, carbon black, silica, and a silane coupling agent, and containing a sulfide silane coupling agent and an amino silane coupling agent as the silane coupling agent. ,
   The conveyor belt manufacturing method which implements the 2nd process which forms at least the said back surface cover rubber layer with the rubber composition produced at the 1st process among the said surface side cover rubber layer and the said back surface cover rubber layer.
5. In the first step,
   First kneading a first compound in which one or more components among all the components contained in the rubber composition are insufficient;
   Carrying out a second kneading comprising a kneaded product obtained by the first kneading and kneading the second compound supplemented with the deficient components,
   In the first kneading, the first compound contains an amino silane coupling agent, and the first compound is kneaded with a sulfide silane coupling agent being insufficient,
   The conveyor belt manufacturing method according to claim 4, wherein in the second kneading, the rubber composition is prepared by kneading a second compound supplemented with a sulfide-based silane coupling agent.
6. Rubber composition comprising a diene rubber, carbon black, silica, and a silane coupling agent, and a sulfide silane coupling agent and an amino silane coupling agent as the silane coupling agent.
7. The content of the amino silane coupling agent with respect to 100 parts by mass of silica is Xa parts by mass,
   The rubber composition according to claim 6, wherein when the content of the alkylamine with respect to 100 parts by mass of silica is Xb parts by mass, all of the following formulas (1) to (3) are satisfied.
   
   3 ≦ Xa ≦ 10 (1)
   1 ≦ Xb ≦ 7 (2)
   4 ≦ (Xa + Xb) ≦ 14 (3)
   
   

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