JP2011074344A - Rubber composition for conveyer belt and conveyer belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a conveyer belt, which can keep fundamental physical properties such as high breaking strength, tear strength and abrasion resistance, and can perform sufficient power consumption decrease; and to provide a conveyer belt. <P>SOLUTION: The problems are solved with a rubber composition for conveyer belt, containing a rubber component comprising natural rubber (NR) and polybutadiene rubber (BR) and carbon black having 20-45 m<SP>2</SP>/g nitrogen absorption specific surface area (N<SB>2</SB>SA), and surface treated clay, wherein, the total content of the carbon black and the surface treated clay is 10-30 pts.mass per 100 pts.mass rubber component and the compounding ratio of the carbon black and the surface treated clay (carbon black/surface treated clay) is 0.3-3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

Conveyor belts are often used for transporting materials, etc., but they are required to be larger and stronger due to increased transport volume and improved transport efficiency. Has also appeared.
For this reason, the equipment cost and the power consumption are increasing, and a belt conveyor system with low cost and low power consumption is demanded. In particular, the cost of the belt conveyor is reduced by improving the rubber characteristics constituting the belt. Low power consumption is being studied.

For example, in Patent Document 1, “loss of physical properties of rubber on the inner surface of a belt that is in contact with the pulley of the conveyor belt in a conveyor belt used in a conveyance system for an article that is wound around a driving pulley and an idle pulley and travels. Conveyor belt characterized in that factor (tan δ) and dynamic elastic modulus (E ′) are 0.04 ≦ tan δ ≦ 0.12 and E ′ ≧ 20 kgf / cm ² , respectively, and “drive pulley”. A conveyor belt used in a system for conveying articles that are wound around an idler pulley, and the inner surface rubber of the conveyor belt is a polymer comprising 40 to 100 parts by weight of natural rubber and 60 to 0 parts by weight of BR rubber. The conveyor belt characterized by blending 20 to 55 parts by weight of carbon black ”.

  Further, Patent Document 2 states that in a conveyor belt provided with a cover rubber in contact with the belt support member on at least one of the upper and lower surfaces of the core body layer, the cover rubber contains silica and a silane coupling agent. Conveyor belts characterized by the above. "

Further, according to the present applicant, “a rubber composition for a conveyor belt containing 30 to 65 parts by mass of carbon black having colloidal characteristics shown below with respect to 100 parts by mass of a rubber component.
1) Nitrogen adsorption specific surface area (N ₂ SA) is 80 (m ² / g) or less 2) Iodine adsorption amount (IA) is 70 (mg / g) or less 3) Dibutyl phthalate (DBP) oil absorption is 100 (cm ³⁾ / 100 g) or more ”, or“ a rubber composition for conveyor belts having a frequency 10 Hz, dynamic strain 2%, loss coefficient tan δ at 20 ° C. is more than 0.120 and less than 0.200 ”(patents). Reference 3).

Further, Patent Document 4 describes in claim 1 that “a rubber selected from the group consisting of the following: (a) natural rubber, rubber derived from a diene monomer, and a mixture thereof;
(B) about 0.1 to about 10 phr of the following general formula (I):

Wherein R is a divalent acyclic aliphatic group having about 2 to 16 carbon atoms, a cycloaliphatic group having about 5 to 20 carbon atoms, about 6 to 18 carbon atoms. Or an aromatic aromatic group having about 7 to 24 carbon atoms, wherein these divalent groups may contain a heteroatom selected from O, N and S; X is 0 Or an integer from 1 to 3; and Y is hydrogen or —CH ₃ ), and (c) from about 0.1 to about 10 phr of the following general formula (II):

Wherein R ¹ is an alkylene group having 1 to 20 carbon atoms, a cycloalkylene group having 6 to 24 carbon atoms, an arylene group having 6 to 18 carbon atoms, or 7 to 25 carbons. Alkali-lene group having atoms and the following formula:

And is selected from the group consisting of divalent groups. A rubber compound having improved vulcanization return resistance comprising a bisbenzothiazolyldithio compound having The rubber compound according to claim 1, which is in the shape of a tire, a hose, a belt or a shoe sole, is described in claim 2.

JP-A-11-139523 JP 2004-10215 A Japanese Patent Laid-Open No. 2004-18752 JP-A-10-77361

However, the conveyor belt described in Patent Document 1 is intended to reduce power consumption by reducing the tan δ value. However, if the tan δ value is too small, the breaking strength (T _B ) and the breaking elongation (E _B ) Also decreases, and the tear strength and fatigue resistance may be inferior, causing surface damage to the cover rubber, etc. when the conveyor belt is running, causing the conveyor belt surface to fail and causing unstable operation. .
In addition, the conveyor belt described in Patent Document 2 has a problem that power consumption is not sufficiently reduced because the energy loss index is high.
Furthermore, since the energy loss index of the conveyor belt using the rubber composition for the conveyor belt described in Patent Document 3 is high, the power consumption is reduced due to differences in the belt operation line (for example, the gradient or bending of the line). There was a case that was not enough.
Furthermore, it was found that the belt using the compound described in Patent Document 4 has poor wear resistance when the natural rubber (NR) is more than 80 parts by mass. Furthermore, NR is if less than 25 parts by weight reduces the 25% modulus (M _25), energy loss index ([Delta] H) is increased, it was found that there is a problem that can not be achieved to reduce the power consumption. Furthermore, since the compound described in the cited document 4 contains silica but does not contain a silane coupling agent and diethylene glycol, there is a problem that the loss coefficient tan δ and the energy loss index (ΔH) become large and the power consumption cannot be reduced. I understood that.

  Therefore, the present invention provides a rubber composition for a conveyor belt and a conveyor belt that can maintain basic physical properties such as high breaking strength, tear strength, and wear resistance and can sufficiently reduce power consumption. Let it be an issue.

In order to solve the above-mentioned problems, the present inventors diligently studied and completed the present invention.
The present invention includes the following (1) to (6).
(1) a rubber component comprising natural rubber (NR) and polybutadiene rubber (BR), carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 20 to 45 m ² / g, and surface-treated clay, The total content of the carbon black and the surface treatment clay is 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component, and the compounding ratio of the carbon black and the surface treatment clay (carbon black / surface treatment) A rubber composition for conveyor belts having a clay) of 0.3 to 3.
(2) The rubber composition for a conveyor belt according to (1), wherein the polybutadiene rubber (BR) is a terminal-modified polybutadiene rubber.
(3) The rubber composition for a conveyor belt according to (2), wherein the terminal-modified polybutadiene rubber is obtained by NMP modification treatment.
(4) The amount ratio (NR / BR) between the natural rubber (NR) and the polybutadiene rubber (BR) in the rubber component is 50/50 to 90/10. The rubber composition for conveyor belts in any one.
(5) The rubber composition for conveyor belts according to any one of (1) to (4), wherein the surface-treated clay is a mercapto surface-treated clay.
(6) A conveyor belt having an upper surface cover rubber layer, a reinforcing layer, and a lower surface cover rubber layer, wherein at least the rear surface of the lower surface cover rubber layer is any one of the above (1) to (5) Conveyor belt formed by a rubber composition for use.

  According to the present invention, it is possible to provide a rubber composition for a conveyor belt and a conveyor belt that can maintain basic physical properties such as high breaking strength, tear strength, and wear resistance and can sufficiently reduce power consumption. it can.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the conveyor belt of the present invention.

The present invention will be described.
The present invention comprises the composition of the present invention and the conveyor belt of the present invention.

First, the composition of the present invention will be described.
The composition of the present invention includes a rubber component composed of natural rubber (NR) and polybutadiene rubber (BR), carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 20 to 45 m ² / g, surface-treated clay, The total content of the carbon black and the surface-treated clay is 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component, and the mixing ratio of the carbon black and the surface-treated clay (carbon It is a rubber composition for conveyor belts in which black / surface-treated clay is 0.3 to 3 (mass ratio).

The rubber component contained in the composition of the present invention will be described.
The rubber component contained in the composition of the present invention comprises natural rubber (NR) and polybutadiene rubber (BR) (hereinafter also simply referred to as “NR” and “BR”).

  The NR constituting the rubber component is a polymer having a structure in which cis-1,4-polyisoprene is bonded to the head and tail, and a commonly used natural rubber can be used.

  The BR constituting the rubber component preferably has a weight average molecular weight of 500,000 or more, more preferably 550,000 or more. When the weight average molecular weight is within this range, the rupture strength and tear strength after vulcanization of the resulting composition of the present invention are improved, and the wear resistance is also improved.

In the rubber composition of the present invention, BR is preferably a terminal-modified polybutadiene rubber.
The terminal-modified polybutadiene rubber is not particularly limited as long as the terminal is a modified BR. In addition, as a method for modifying the terminal of BR, for example, a method of modifying the terminal (active terminal) of BR using a denaturing agent can be used.
Specific examples of such modifiers include, for example, tin halides such as tin tetrachloride and tin tetrabromide; halogenated organotin compounds such as tributyltin chloride; silicon compounds such as silicon tetrachloride and chlorotriethylsilane. An isocyanate group-containing compound such as phenyl isocyanate; an amide compound such as N-methylpyrrolidone (NMP); a lactam compound; a urea compound; an isocyanuric acid derivative; Among these, BR modified with NMP is preferable. This is because the rupture strength and tear strength after vulcanization of the obtained composition of the present invention are improved, and wear resistance is also improved.

  By using such a terminal-modified polybutadiene rubber, the loss coefficient tan δ and energy loss index (ΔH) to be described later after vulcanization of the resulting composition of the present invention are both in a favorable range, so that power consumption is reduced. Can be sufficiently achieved. This is presumably because the modified end portion contributes to crosslinking, and thus the crosslinking density after vulcanization is increased.

A commercially available product can be used as the terminal-modified polybutadiene having a weight average molecular weight of 500,000 or more.
Specific examples include Nipol BR1250H (weight average molecular weight: 570,000, NMP modified) manufactured by Nippon Zeon.

Further, the amount ratio (NR / BR) of NR and BR in the rubber component is preferably 50/50 to 90/10, more preferably 60/40 to 85/15, and 70/30. More preferably, it is -80/20.
When the content ratio of NR and BR is in the above range, the resulting composition of the present invention has good rupture strength, tensile strength and abrasion resistance after vulcanization, and maintains the basic physical properties as a conveyor belt. can do. This is considered to be because the compatibility between NR and BR is improved, and the reinforcement is further improved.

  In the composition of the present invention, the content of the rubber component is preferably 60 to 75% by mass, and more preferably 67 to 72% by mass.

The carbon black contained in the composition of the present invention will be described.
Carbon black-containing compositions of the present invention, the nitrogen adsorption specific surface area (N ₂ SA) is 20~45m ² / g, is preferably 25~42m ² / g, in 27~40m ² / g More preferably. This is because the resulting composition of the present invention has good rupture strength, tensile strength and abrasion resistance after vulcanization, and can maintain the basic physical properties of the conveyor belt.
The nitrogen adsorption specific surface area (N ₂ SA) is measured according to ASTM D3037-89.

  As the carbon black, FEF-based or GPF-based carbon black for rubber classified by a general name can be used, and an FEF-based one is preferable. This is because the basic physical properties such as breaking strength, tear strength and abrasion resistance of the composition of the present invention obtained are further improved.

The surface-treated clay contained in the composition of the present invention will be described.
The surface-treated clay contained in the composition of the present invention is a surface-treated clay.
From the viewpoint of excellent reinforcement and viscoelasticity, the surface-treated clay is preferably a surface-treated clay having a functional group capable of reacting with a rubber component, and more preferably a mercapto surface-treated clay. The mercapto surface-treated clay is a surface-treated clay having a mercapto group.

The surface-treated clay is not particularly limited with respect to its production method. The clay used in producing the surface-treated clay is not particularly limited, and examples thereof include kaolin clay. Examples of the surface treatment agent used when producing the surface-treated clay include an organic compound having a reactive group capable of reacting with the clay and a functional group capable of reacting with the rubber component. Examples of functional groups capable of reacting with the rubber component include amino groups and mercapto groups. Specific examples of the surface treatment agent include, for example, alkoxysilyl groups (wherein _{n in the} formula —SiOR _n is an integer of 1 to 3, and other groups bonded to silicon atoms when n = 1 or 2 are not particularly limited). For example, an alkyl group may be mentioned).
For example, when producing a surface-treated clay using a mercaptosilane having an alkoxysilyl group as a surface treating agent, the mercapto group is imparted to the clay surface by the reaction of the alkoxysilyl group of mercaptosilane with the clay.
And the pendant (for example, functional group like a mercapto group) which surface treatment clay has carries out a crosslinking reaction with rubber | gum can form a chemical bond, and can express reinforcement property to a conveyor belt.

  In the composition of the present invention, the total content of the carbon black and the surface-treated clay is 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component (A). If it is this range, basic physical properties, such as breaking strength of a rubber composition, tear strength, and abrasion resistance, can be improved. The content is preferably 15 to 28 parts by mass, and particularly preferably 20 to 25 parts by mass in that these physical properties can be improved and the power consumption can be further reduced. If the content is too low, the rolling processability is inferior and the tensile strength tends to decrease. If the content is too high, tan δ described later tends to increase and ΔH and ΔH (index) also tend to increase. In addition, the viscosity of the composition is increased, the Mooney scorch is shortened, burns may occur, and rolling may not be possible.

  In the composition of the present invention, the compounding ratio of the carbon black and the surface-treated clay (carbon black / surface-treated clay: mass ratio) is 0.3 to 3, preferably 0.5 to 2.5. More preferably, it is 1.0-2.0. This is because the resulting composition of the present invention has good rupture strength, tensile strength and abrasion resistance after vulcanization, and can maintain the basic physical properties of the conveyor belt.

  In addition to the rubber component, the carbon black, and the surface treatment clay, the composition of the present invention contains a crosslinking agent such as a vulcanizing agent, a vulcanization aid, and a vulcanization accelerator, and a vulcanization retarder. In the range not impairing the object of the present invention, a compounding agent, a polymer and the like may be contained.

  The content of the vulcanizing agent, vulcanization accelerator, and vulcanization aid is preferably 0.1 to 10 parts by mass, and 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component. Particularly preferred. If the amount is less than 0.1 parts by mass, vulcanization is insufficient and the rubber composition is soft, and ΔH, which will be described later, may increase. The properties (stretchability, etc.) may be impaired and may not be suitable as a conveyor belt material.

The composition of the present invention may also contain a vulcanization retarder.
The content of the vulcanization retarder is preferably 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of additives and compounding agents include reinforcing agents (fillers), anti-aging agents, antioxidants, silane coupling agents, pigments (dyes), plasticizers, thixotropic agents, ultraviolet absorbers, flame retardants, Examples include solvents, surfactants (including leveling agents), dispersants, dehydrating agents, rust preventives, adhesion-imparting agents, antistatic agents, fillers (fillers), and processing aids.
As these additives and compounding agents, those generally used for rubber compositions can be used. Their blending amounts are not particularly limited and can be arbitrarily selected.

  The composition of the present invention is produced by adding the rubber component, the carbon black, the surface treatment clay, and various additives as necessary, kneading with a Banbury mixer or the like, and then vulcanizing agent, vulcanization aid. An agent and a vulcanization accelerator can be added and kneaded by a kneading roll machine or the like.

  The composition of the present invention can be vulcanized under the usual conditions. For example, it can be performed by heating at a temperature of about 140 to 150 ° C. for 0.5 hours.

When the composition of the present invention is used as a conveyor belt, the power consumption can be reduced, and the power consumption of the belt conveyor device can be reduced.
Moreover, since carbon black having specific colloidal characteristics is blended in the composition of the present invention, power consumption can be reduced when a conveyor belt is used, and high breaking strength, tear strength, and abrasion resistance can be maintained.
In particular, as a conveyor belt used in a belt conveyor device having a long transportation distance or a belt conveyor device having a large amount of transported goods, it exhibits superior performance such as power saving and high breaking strength.
The conveyor belt of the present invention exhibits excellent performance when used in the above apparatus, but it goes without saying that it can also be used in apparatuses other than these apparatuses (for example, conventional apparatuses having a short transportation distance). Performances such as power saving and high breaking strength can be exhibited.

Next, the conveyor belt of the present invention will be described.
The conveyor belt of the present invention can be formed using the composition of the present invention. It is preferable to use the composition of the present invention for at least the rubber on the back surface (in FIG. 1, the outer layer 16) that contacts the roller.
The conveyor belt of this invention is not specifically limited about the structure.
The conveyor belt of the present invention is, for example, a conveyor belt having an upper cover rubber layer, a reinforcing layer, and a lower cover rubber layer, and at least the back surface of the lower cover rubber layer is the rubber composition for conveyor belts of the present invention. Is formed as one of preferred embodiments. Moreover, it is mentioned as one of the preferable aspects that it is a conveyor belt which consists of an upper surface cover rubber layer, a reinforcement layer, and a lower surface cover rubber layer.
Hereinafter, an example of the conveyor belt of the present invention will be shown.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the conveyor belt of the present invention. In FIG. 1, 1 is a conveyor belt, 2 is a top cover rubber layer (cover rubber layer), 3 is a reinforcing layer, 4 is a bottom cover rubber layer (back cover rubber layer), 5 is a transporting surface, 11 and 16 are Outer layers 12 and 15 are inner layers.
As shown in FIG. 1, the conveyor belt 1 of the present invention has a reinforcing layer 3 as a central layer, and an upper cover rubber layer 2 and a lower cover rubber layer 4 are provided on both sides thereof. The lower cover rubber layer 4 is composed of two layers of an outer layer 16 and an inner layer 15. The outer and inner layers (outer layer 11 and inner layer 12, outer layer 16 and inner layer 15) of upper surface cover rubber layer 2 and lower surface cover rubber layer 4 are preferably formed using different rubber compositions.

In FIG. 1, the upper cover rubber layer 2 is composed of two layers, an outer layer 11 and an inner layer 12. However, in the conveyor belt of the present invention, the number of layers constituting the upper cover rubber layer 2 is limited to two. 1 may be sufficient and 3 or more may be sufficient. In the case of 3 or more, these layers may be formed using different rubber compositions.
The same applies to the bottom cover rubber layer 4.
The outer layer 11 constituting the transported object conveying surface 5 of the upper cover rubber layer 2 is preferably formed from a rubber composition having excellent heat resistance, wear resistance, oil resistance, etc. Therefore, the upper cover rubber layer 2 is It is preferably composed of two layers.
As described above, the outer layer 16 constituting the back surface (the surface in contact with the roller) of the lower cover rubber layer 4 is preferably formed using the composition of the present invention in order to reduce power consumption. The inner layer 15 of the lower cover rubber layer 4 is preferably formed from another rubber composition due to manufacturing cost reduction or the like. Therefore, the lower cover rubber layer 4 is preferably composed of two layers.

The reinforcing layer 3 is not particularly limited and can be appropriately selected from those used for ordinary conveyor belts. For example, a rubber paste is applied and infiltrated into a material made of cotton and chemical fibers or synthetic fibers. And a woven material obtained by folding an RFL-treated one, a special woven nylon canvas, a steel cord, and the like.
A reinforcement layer may be used independently and may laminate | stack and use 2 or more types of things.
The shape of the reinforcing layer 3 is also not particularly limited, and may be a sheet shape as shown in FIG. 1 or may be a wire-like reinforcing wire embedded in parallel.

The rubber composition for forming the inner layer 12 of the upper cover rubber layer 2 and the inner layer 15 of the lower cover rubber 4 is not particularly limited, and a rubber composition used for an ordinary conveyor belt can be appropriately selected and used.
The rubber composition may be used alone or in combination of two or more.

  The rubber composition for forming the outer layer 11 of the upper cover rubber layer 2 is not particularly limited, and a rubber composition used for a normal conveyor belt is made of basic characteristics (for example, heat resistance, wear resistance) required for the inner layer. The oil resistance, oil resistance, etc.) can be appropriately selected and used.

It does not specifically limit as a manufacturing method of the conveyor belt of this invention, The method used normally can be employ | adopted.
For example, first, the composition of the present invention is formed into a sheet shape using a calendar or the like, and then the obtained sheet and the sheet used for forming other layers and the reinforcing layer are arranged in a predetermined order. A method of laminating and pressurizing at a temperature of 150 to 170 ° C. for 10 to 60 minutes can be mentioned.

  Since the conveyor belt of the present invention uses the composition of the present invention at least for the outer layer of the lower cover rubber, it can reduce power consumption or power consumption while maintaining high breaking strength, wear resistance, and the like.

The following examples further illustrate the composition of the present invention in more detail, but the present invention is not limited thereto.
<Manufacture of rubber composition for conveyor belt>
A rubber composition for conveyor belts was produced by blending (parts by mass) with the composition shown in Table 1.

The obtained rubber composition for a conveyor belt is formed into a sheet shape, vulcanized by heating at 148 ° C. for 30 minutes, and the obtained vulcanized sheet is used as a test piece to obtain tensile stress (M ₂₅ ) and breaking strength (T _B ) , Elongation at break (E _B ), tear strength (TrA), wear resistance, hardness and loss factor (tan δ) were measured, and ΔH was calculated from the following formula [1]. The results are shown in Table 1.
ΔH = (SpGr × tan δ) / M ₂₅ formula [1]

<Tensile stress (M _25)>
Tensile stress M ₂₅ is in accordance with the method described in JIS K 6251, to measure the stress (MPa) Tensile at elongation of 25% (measuring temperature 23 ° C.).

<Blank tensile test>
Based on the method described in JIS K 6251, the breaking strength (T _B ) and the breaking elongation (E _B ) were measured.
<Tear Strength TrA>
The tear strength (TrA) was measured in accordance with the method described in JIS K6252.

<Abrasion resistance>
A DIN abrasion test was conducted according to JIS-K6264-2: 2005 using a test piece cut out from each prepared vulcanized rubber composition into a disc shape (diameter 16.2 mm × thickness 6 mm). The amount of wear (mm ³ ) when a DIN wear test was performed at room temperature was measured.

<Hardness>
Hardness (HS) was measured according to the method described in JIS K 6253.

<Loss factor (tan δ)>
Using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho, the sample was stretched 10% at a measurement temperature of 20 ° C., and a vibration with an amplitude of ± 2% was applied at a frequency of 10 Hz.

<ΔH>
From the measured value, ΔH was determined by the above equation [1].

Evaluation of tensile strength (M ₂₅ ), breaking strength (T _B ), elongation at break (E _B ), tear strength (tear), wear resistance (amount of wear), ΔH that satisfies the required characteristics of power-saving conveyor belts The standards are as shown in Table 2 below.

In the examples and comparative examples, the following rubbers, additives and the like were used.
Natural rubber (NR): Polybutadiene rubber manufactured by TECK BEE HANG (BR terminal modified): Nipol BR 1250H, manufactured by Nippon Zeon Co., Ltd., weight average molecular weight 570,000, polybutadiene rubber modified with NMP at the end Polybutadiene rubber (BR): Nipol BR 1220, manufactured by Nippon Zeon Co., Ltd., weight average molecular weight 460,000 carbon black (FEF): Dia Black E, manufactured by Mitsubishi Chemical Co., Ltd., nitrogen adsorption specific surface area 38 m ² / g
Carbon black (GPA): HTC # G, manufactured by Nippon Kayaku Co., Ltd., nitrogen adsorption specific surface area 27 m ² / g
Carbon black (HAF): Show black N330, manufactured by Showa Cabot Corporation, nitrogen adsorption specific surface area 67 m ² / g
Surface treatment clay 1: MERCAP 100, manufactured by Kentucky Tennessee Clay Company, Inc., surface treatment clay having a mercapto group Surface treatment clay 2: Nucap 290, J. Mol. M.M. Surface treatment clay having a mercapto group, manufactured by Huber Corporation, untreated surface clay: SUPREX PLAY, manufactured by Kentucky Tennessee Clay Company, silica: Nipseal AQ, manufactured by Tosoh Silica Co., Ltd., zinc oxide: manufactured by Shodo Chemical Co., Ltd., stearic acid: Japan Diethylene glycol manufactured by Yushi Co., Ltd .: Nippon Shokubai Co., Ltd. Silane coupling agent: Si69, manufactured by Evonik Degussa, Inc. Sulfur: oil-treated sulfur, manufactured by Karuizawa Seirensho

As is clear from the results shown in Table 1, Comparative Example 1 containing clay that has not been surface-treated, Comparative Example 2 having a nitrogen adsorption specific surface area (N ₂ SA) exceeding 45 m ² / g, and containing surface-treated clay Comparative Example 5 in which carbon black / surface-treated clay blend ratio exceeds 3, Comparative Example 7 and 8 in which carbon black and surface-treated clay are not included, Comparative Example 9 in which carbon black and surface-treated clay are not included, and the total content of carbon black and surface-treated clay is rubber In Comparative Examples 11 and 12, which exceed 30 parts by mass with respect to 100 parts by mass of the component, ΔH is high and power consumption cannot be sufficiently reduced. Further, Comparative Example 3 containing no polybutadiene rubber, Comparative Example 4 containing no carbon black, and Comparative Example 6 having a carbon black / surface-treated clay compounding ratio of less than 0.3 are inferior in wear resistance and maintain basic physical properties. I couldn't. Comparative Example 10 in which the total content of carbon black and surface-treated clay was less than 10 parts by mass with respect to 100 parts by mass of the rubber component had a low 25% modulus and could not maintain basic physical properties. In Comparative Example 12 in which the total content of carbon black and surface-treated clay exceeds 30 parts by mass with respect to 100 parts by mass of the rubber component, the tear strength is low and the basic physical properties cannot be maintained.
On the other hand, Examples 1-11 maintain basic physical properties, such as high breaking strength, tear strength, and abrasion resistance, (DELTA) H is low, and can fully aim at reduction of power consumption.

1: Conveyor belt 2: Upper cover rubber layer 3: Reinforcement layer 4: Lower cover rubber layer 5: Transported material transport surface 11, 16: Outer layer 12, 15: Inner layer

Claims (6)

A rubber component comprising natural rubber (NR) and polybutadiene rubber (BR);
Carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 20 to 45 m ² / g;
Containing surface treatment clay,
The total content of the carbon black and the surface-treated clay is 10 to 30 parts by mass with respect to 100 parts by mass of the rubber component,
A rubber composition for a conveyor belt, wherein a mixing ratio of the carbon black and the surface-treated clay (carbon black / surface-treated clay) is 0.3 to 3.   The rubber composition for a conveyor belt according to claim 1, wherein the polybutadiene rubber (BR) is a terminal-modified polybutadiene rubber.   The rubber composition for a conveyor belt according to claim 2, wherein the terminal-modified polybutadiene rubber is obtained by NMP modification treatment.   The conveyor according to any one of claims 1 to 3, wherein a quantity ratio (NR / BR) of the natural rubber (NR) and the polybutadiene rubber (BR) in the rubber component is 50/50 to 90/10. A rubber composition for a belt.   The rubber composition for a conveyor belt according to any one of claims 1 to 4, wherein the surface-treated clay is a mercapto surface-treated clay. A conveyor belt having an upper cover rubber layer, a reinforcing layer and a lower cover rubber layer,
A conveyor belt in which at least the back surface of the bottom cover rubber layer is formed by the rubber composition for a conveyor belt according to any one of claims 1 to 5.