JP6282406B2 - Rubber composition for air levitation conveyor belt and air levitation conveyor belt using the same - Google Patents

Description

  The present invention relates to a rubber composition for an air levitation conveyor belt and an air levitation conveyor belt using the same.

  Conventionally, an air floating conveyor belt has been used as an energy-saving conveyor belt. The air-floating conveyor belt usually has an upper cover rubber layer, a reinforcing layer, and a lower cover rubber layer. For example, Patent Document 1 has been proposed as a rubber composition used for forming a lower cover rubber layer of an air-floating conveyor belt.

JP 2002-217725 A

In the air-lifting conveyor belt, the lower cover rubber layer contacts the belt support at the trough conversion part until it completely troughs from the pulley, the part where the conveyed object is dropped from the chute at the start end of the forward path of the belt, etc. As a result, the driving resistance of the belt increases. Therefore, the bottom cover rubber layer needs to have low adhesion and low friction.
At the same time, in order to extend the life of the air-floating conveyor belt, the lower cover rubber layer needs to have wear resistance.
However, the inventor of the present application has found that a bottom cover rubber layer produced using a conventional rubber composition for an air levitation conveyor belt has high adhesion and friction properties and low wear resistance.
Then, an object of this invention is to provide the rubber composition for air levitation type conveyor belts which is excellent in low adhesiveness, low friction property, and abrasion resistance, and an air levitation type conveyor belt using the same.

  As a result of earnest research to solve the above problems, the inventor of the present invention has 100 parts by mass of a rubber component containing styrene butadiene rubber and butadiene rubber in a mass ratio (SBR / BR) of 95/5 to 70/30. The present inventors have found that a rubber composition containing 70 parts by mass or more of carbon black becomes a rubber composition for air-floating conveyor belts that is excellent in low adhesion, low friction, and wear resistance, and completed the present invention.

That is, the present invention provides the following rubber composition for an air levitation conveyor belt and an air levitation conveyor belt using the same.
1. For air-floating conveyor belts containing 70 parts by mass or more of carbon black with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber in a mass ratio of 95/5 to 70/30 (SBR / BR). Rubber composition.
2. Air levitation conveyor belts rubber composition according to the 1 24M4DBP absorption of the carbon black is 90cm ^3/100 g or more.
3. 3. The rubber composition for an air-lifting conveyor belt according to 1 or 2 above, wherein the amount of the carbon black is 110 parts by mass or less.
4). 4. The rubber composition for an air flotation type conveyor belt according to any one of the above 1 to 3, wherein the carbon black has an N ₂ SA of 80 m ² / g or more.
5. 5. The rubber composition for an air flotation type conveyor belt according to any one of the above 1 to 4, wherein the rubber component further contains natural rubber.
6). 5. The rubber composition for an air flotation type conveyor belt according to any one of the above 1 to 4, wherein the rubber component comprises styrene butadiene rubber and butadiene rubber.
7). An air levitation conveyor belt having a bottom cover rubber layer produced using the rubber composition for an air levitation conveyor belt according to any one of 1 to 6 above.

The rubber composition for an air flotation type conveyor belt of the present invention is excellent in low adhesion, low friction and wear resistance.
The air levitation conveyor belt of the present invention is excellent in low adhesion, low friction and wear resistance.

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

The present invention will be described in detail below.
The rubber composition for an air flotation type conveyor belt of the present invention (the rubber composition of the present invention)
For air-floating conveyor belts containing 70 parts by mass or more of carbon black with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber in a mass ratio of 95/5 to 70/30 (SBR / BR). It is a rubber composition.
The rubber composition of the present invention is excellent in low tack, low friction and wear resistance. Thus, since low adhesiveness and low friction can be improved, it is possible to reduce the driving resistance of the belt and to save power in the belt line. Furthermore, since the wear can be improved, the life of the conveyor belt can be extended.

The rubber component will be described below. The rubber component contained in the rubber composition of the present invention is not particularly limited except that it includes styrene butadiene rubber and butadiene rubber.
Styrene butadiene rubber (SBR) is not particularly limited as long as it is a copolymer of styrene and butadiene.
The weight average molecular weight of SBR is preferably 200,000 to 1,000,000 from the viewpoint that it is excellent in low tackiness, low friction and wear resistance, and has a low viscosity of the rubber composition and excellent workability. More preferably, it is 800,000. The weight average molecular weight of SBR was measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.
The amount of styrene in SBR is preferably 15 to 35% by mass of SBR, from the viewpoint of being excellent in low tack, low friction and wear resistance, and having a low viscosity of the rubber composition and excellent workability. More preferably, it is 30% by mass.

Butadiene rubber (BR) is not particularly limited.
The weight average molecular weight of the butadiene rubber is preferably 200,000 to 900,000 from the viewpoint of being excellent in low tackiness, low friction and wear resistance, and having a low viscosity of the rubber composition and excellent workability, More preferably, it is ˜700,000. The weight average molecular weight of BR was measured in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

In the present invention, the mass ratio (SBR / BR) of styrene butadiene rubber to butadiene rubber is 95/5 to 70/30. From the viewpoint of being excellent in low adhesiveness, low friction and wear resistance, and having a low viscosity of the rubber composition and excellent workability, it is preferably less than 90/10 and more preferably 89/11 to 75/25. Is more preferable, and it is still more preferable that it is 85 / 15-80 / 20.
The total amount of styrene butadiene rubber and butadiene rubber can be 90 to 100% by mass in the rubber component.

From the viewpoint of excellent rubber strength, the rubber component further includes natural rubber as one of preferred embodiments. Natural rubber is not particularly limited.
The amount of the natural rubber can be 10 parts by mass or less, preferably 0 to 10 parts by mass, in 100 parts by mass of the rubber component.

The rubber component is preferably composed of styrene butadiene rubber and butadiene rubber from the viewpoint of being excellent in low adhesiveness, low friction and abrasion resistance, and having a low viscosity of the rubber composition and excellent workability.
The rubber component is not particularly limited for its production. For example, a conventionally well-known thing is mentioned.

The carbon black will be described below.
The carbon black contained in the rubber composition of the present invention is not particularly limited. For example, a conventionally well-known thing is mentioned.

24M4DBP absorption of carbon black is low tack, low friction property, distinguished by abrasion resistance, from the viewpoint of the viscosity of the rubber composition is excellent in workability low, preferably at 90cm ^3/100 g or more, 95cm ³ / 100 g or more is more preferable. The 24M4DBP oil absorption is determined in accordance with JIS K6217-4.

The N ₂ SA (nitrogen adsorption specific surface area) of the carbon black is 80 m ² / g or more from the viewpoint of being excellent in low adhesiveness, low friction and wear resistance, and having a low viscosity of the rubber composition and excellent workability. Of 110 m ² / g or more is more preferable. N ₂ SA of carbon black is a value measured according to JIS K6217-2: 2001 “Part 2: Determination of specific surface area—nitrogen adsorption method—single point method”.

In the present invention, the amount of carbon black is 70 parts by mass or more with respect to 100 parts by mass of the rubber component. The amount of carbon black is more than 80 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoints of low adhesiveness, low friction and wear resistance, and low viscosity of the rubber composition and excellent workability. Is preferable, more than 90 parts by mass, more preferably 95 parts by mass or more, and particularly preferably 96 parts by mass or more.
Carbon blacks can be used alone or in combination of two or more.
The upper limit of the amount of carbon black can be 120 parts by mass or less with respect to 100 parts by mass of the rubber component. The amount of carbon black is preferably 110 parts by mass or less, from the viewpoint of being excellent in low tack, low friction, and abrasion resistance, and having a low viscosity of the rubber composition and excellent workability. More preferably.

  The rubber composition of the present invention may further contain an additive within the intended range, if necessary, in addition to the above components. Examples of the additive include a vulcanizing agent (for example, sulfur), a vulcanization aid, a vulcanization accelerator, a vulcanization retarder, and a compounding agent. Examples of compounding agents include reinforcing agents (fillers) other than carbon black, anti-aging agents, antioxidants, pigments (dyes), plasticizers, thixotropic agents, ultraviolet absorbers, flame retardants, solvents, and surfactants. Agents (including leveling agents), dispersants, dehydrating agents, rust preventives, adhesion-imparting agents, antistatic agents, fillers (fillers), processing aids and the like. The additive amount of the additive is not particularly limited and can be arbitrarily selected.

The rubber composition of the present invention is produced by kneading a rubber component, carbon black, and a compounding agent that can be used as necessary with a roll, a kneader, a Banbury mixer, etc., and then a vulcanizing agent, a vulcanizing auxiliary, It can be carried out by adding an accelerator or a vulcanization retarder and kneading with a kneading roll.
The rubber composition of the present invention can be vulcanized under usual conditions. Specifically, for example, it is performed by heating and pressurizing under a temperature of about 140 to 150 ° C.

  As an application of the rubber composition of the present invention, for example, an air floating type conveyor belt can be mentioned.

The air levitation conveyor belt of the present invention will be described below.
The air levitation conveyor belt of the present invention (conveyor belt of the present invention) is an air levitation conveyor belt having a bottom cover rubber layer manufactured using the rubber composition for an air levitation conveyor belt of the present invention.
The rubber composition used for the conveyor belt of the present invention is not particularly limited as long as it is a rubber composition for an air floating conveyor belt of the present invention. In the conveyor belt of the present invention, since the lower cover rubber layer of the conveyor belt is manufactured by the rubber composition of the present invention, it has excellent low adhesion, low friction, low driving resistance, excellent wear resistance and long life. It is.

One preferred embodiment of the conveyor belt of the present invention is an air-floating conveyor belt having an upper cover rubber layer, a reinforcing layer, and a lower cover rubber layer.
One preferred embodiment is that at least the back surface of the bottom cover rubber layer is formed by the rubber composition for an air-floating conveyor belt of the present invention.
The conveyor belt of the present invention will be described below with reference to the accompanying drawings. The conveyor belt of the present invention is not limited to the drawings.

  FIG. 1 is a cross-sectional view schematically showing an example of a preferred embodiment of the conveyor belt of the present invention. In FIG. 1, 1 indicates a conveyor belt. The conveyor belt 1 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 upper cover rubber layer 2 is composed of two layers, an outer layer 11 and an inner layer 12. The lower cover rubber layer 4 is composed of two layers, an outer layer 16 and an inner layer 15. The conveyor belt 1 has a conveyed product transport surface 5.

In the present invention, the outer layer and the inner layer of the lower surface cover rubber layer may be formed using different rubber compositions. The same applies to the upper cover rubber layer.
The number of layers constituting the bottom cover rubber layer may be one or more. It can be 2 or more. The same applies to the upper cover rubber layer.
Since the outer layer constituting the transporting surface (5 in FIG. 1) of the upper cover rubber layer is preferably formed from a rubber composition having excellent heat resistance, wear resistance, oil resistance, etc., the upper cover rubber layer Is preferably composed of two or more layers. Examples of the rubber composition used for producing the upper cover rubber layer include conventionally known rubber compositions.
The outer layer (16 in FIG. 1) constituting the back surface of the bottom cover rubber layer can be formed by the rubber composition for conveyor belts of the present invention. Therefore, it can be formed using another rubber composition. The lower cover rubber layer is preferably composed of two or more layers. Examples of the rubber composition used for producing the inner layer of the lower cover rubber layer include conventionally known rubber compositions.

  The core of the reinforcing layer is not particularly limited, and those used for ordinary conveyor belts can be appropriately selected and used. Specific examples thereof include a rubber paste for those made of cotton and chemical fibers or synthetic fibers. Examples include coated, infiltrated, RFL-treated folded, special woven nylon canvas, steel cord, etc. These may be used alone or in combination of two or more. Also good. The shape of the reinforcing layer is not particularly limited, and for example, a sheet-like (FIG. 1) or wire-like reinforcing wire may be embedded in parallel.

  In the conveyor belt of the present invention, the thickness of the lower cover rubber layer is preferably 5 to 20 mm, and more preferably 6 to 15 mm. Here, the thickness of the lower surface cover rubber layer refers to the total thickness of these layers when the lower surface cover rubber layer is composed of an inner layer and an outer layer.

  The manufacturing method of the conveyor belt of this invention is not specifically limited, The method etc. which are normally used are employable. Specifically, first, after kneading the raw material for each cover rubber layer using a roll, kneader, Banbury mixer, etc., it is molded into a sheet shape for each cover rubber layer using a calendar, etc. A method of laminating the obtained layers in a predetermined order so as to sandwich the reinforcing layer and pressurizing at a temperature of 150 to 170 ° C. for 10 to 60 minutes is suitably exemplified.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<Manufacture of rubber composition for air levitation conveyor belt>
Using the components shown in Table 1 below as the composition components (parts by mass) shown in the same table, these were uniformly mixed to produce a rubber composition (rubber composition) for an air flotation type conveyor belt.
<Vulcanization of rubber composition>
The rubber composition produced as described above was heated and pressurized at 148 ° C. for 30 minutes and vulcanized to produce a vulcanized rubber.

<Evaluation of rubber composition>
The rubber composition or vulcanized rubber produced as described above was evaluated as follows. The results are shown in Table 1 below.
-Dynamic friction coefficient The vulcanized rubber produced as described above was cut into a size of 10 mm in length x 10 mm in width x 10 mm in thickness to produce a vulcanized rubber test piece. Place the vulcanized rubber test piece on a disk-shaped iron plate, apply a vertical load of 4.90 N to the vulcanized rubber test piece, and press the vulcanized rubber test piece and the iron plate in a state of 300 mm / min. Rotating at a speed, the horizontal load applied to the rubber specimen was measured.
Then, the applied friction and the measured horizontal load were applied to the following formula to calculate the dynamic friction coefficient. The smaller this value is (less than 0.7), the lower the frictional resistance and the lower the driving resistance.
Coefficient of dynamic friction = horizontal load / vertical load

・ Adhesiveness After measuring the horizontal load, a load meter was set on the vulcanized rubber specimen, and the peel strength when peeling the vulcanized rubber specimen from the iron plate was measured by lifting the vulcanized rubber specimen upward. .
The smaller the peel strength (0.6 kgf or less), the lower the adhesiveness, and the lower the drive resistance.

-DIN abrasion The DIN abrasion test of the vulcanized rubber manufactured as mentioned above was done according to JIS-K6264-2: 2005. The amount of wear (mm ³ ) when a DIN wear test was performed at room temperature was measured.
Those having an abrasion amount of 150 mm ³ or less can be said to be excellent in abrasion resistance.

・ Minimum Mooney viscosity (Vm)
According to the method described in JIS K 6300-1: 2001, the torque applied to the rotor shaft was measured and recorded in Mooney units (M) using an L-shaped rotor under measurement conditions of a measurement temperature of 125 ° C. (this value) Is Mooney viscosity). A Mooney viscosity-time curve was prepared, and the lowest value in this curve was defined as the lowest Mooney viscosity (Vm) at 125 ° C.
When Vm is 80 or less, the processability is excellent.

The details of each component shown in Table 1 are as follows.
・ NR: Natural rubber, RSS # 3
SBR: styrene butadiene rubber, Nipol 1502 (manufactured by Nippon Zeon Co., Ltd.), weight average molecular weight 500,000, styrene content 23.5% by mass
-BR: butadiene rubber, Nipol BR1220 (manufactured by ZEON Corporation), weight average molecular weight 500,000-carbon black 1: ISAF (show black N220, manufactured by Cabot Japan)
Carbon black 2: SAF (Show Black S118, manufactured by Cabot Japan)
・ Carbon black 3: SAF (Niteron # 415UD, manufactured by Nisshin Carbon)
・ Oil: A-OMIX, Sankyo Oil Chemical Co., Ltd. ・ Sulfur: Oil-treated sulfur, Hosoi Chemical Co., Ltd. ・ Vulcanization accelerator: Tetramethylthiuram monosulfide (Sunceller TS, Sanshin Chemical Co., Ltd.)
In Table 1, 24M4DBP absorption units of carbon black 1-3 is cm ^3/100 g, a unit of N ₂ SA is m ² / g.

As is apparent from the results shown in Table 1, Comparative Examples 1 and 2 containing no butadiene rubber had poor wear resistance. Comparative Example 3 containing an excess of butadiene rubber had high tackiness. Comparative Example 4 with a small amount of carbon black had high friction and poor wear resistance.
Exemplary contrast Example 1 to 7 and Reference Example 1-6 low tack, low friction, excellent wear resistance.
Further, when the amount of carbon black is less than 110 parts by mass with respect to 100 parts by mass of the rubber component, the minimum Mooney viscosity is in an appropriate range and the processability is excellent.

DESCRIPTION OF SYMBOLS 1 Conveyor belt 2 Upper surface cover rubber layer 3 Reinforcement layer 4 Lower surface cover rubber layer 5 Carrying material conveyance surface 11, 16 Outer layer 12, 15 Inner layer

Claims (6)

Containing 100 parts by mass or more of carbon black with respect to 100 parts by mass of a rubber component containing styrene-butadiene rubber and butadiene rubber at a mass ratio of 85/15 to 80/20 (SBR / BR),
A rubber composition for an air-floating conveyor belt, wherein the carbon black has an N ₂ SA of 80 m ² / g or more. Air levitation conveyor belts rubber composition according to claim 1 24M4DBP absorption of the carbon black is 90cm ^3/100 g or more.   The rubber composition for an air flotation type conveyor belt according to claim 1 or 2, wherein the amount of the carbon black is 110 parts by mass or less.   The rubber composition for an air flotation type conveyor belt according to any one of claims 1 to 3, wherein the rubber component further contains natural rubber.   The rubber composition for an air flotation type conveyor belt according to any one of claims 1 to 3, wherein the rubber component comprises styrene butadiene rubber and butadiene rubber.   An air levitation conveyor belt having a bottom cover rubber layer produced using the rubber composition for an air levitation conveyor belt according to any one of claims 1 to 5.

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