JP2020007156A - Conveyer belt - Google Patents

Abstract

To provide a conveyer belt that has excellent strength.SOLUTION: The conveyer belt includes a belt main body 1. The belt main body 1 includes: a core body layer 11; and a front cover rubber layer (rubber layer) 12 and a back cover rubber layer (rubber layer) 13 laminated on both sides of the core body layer 11. The cover rubber layers 12, 13 are formed of a rubber composition that is formed by blending and mixing various types of compound agents into a rubber component and heating and pressing the resulted non-crosslinked rubber composition and crosslinking it by a crosslinking agent. The rubber composition forming the front cover rubber layer 12 and the back cover rubber layer 13 contains cellulose type fine fiber 14, thereby imparting excellent strength to the conveyer belt.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conveyor belt.

  It is known to apply rubber compositions containing so-called cellulose fibers to rubber products such as tires.

  For example, Patent Document 1 discloses that a rubber composition containing chemically modified microfibril cellulose having an average fiber diameter of 4 nm to 1 μm is applied to a pneumatic tire.

Japanese Patent No. 4581116

  However, application of a rubber composition containing cellulosic fine fibers to a conveyor belt has not been disclosed so far.

  It is an object of the present invention to provide a conveyor belt having excellent strength.

  The present invention is a conveyor belt having a belt body provided with a rubber layer, wherein the rubber layer contains cellulosic fine fibers.

  According to the present invention, a conveyor belt having excellent strength can be provided.

FIG. 2 is a sectional view of a belt main body 1 of the conveyor belt according to the first embodiment. FIG. 9 is a perspective view of a belt structure 2 of the steeply conveyer conveyor belt according to the second embodiment.

  Hereinafter, embodiments will be described in detail.

[Embodiment 1]
(Conveyor belt)
The conveyor belt V according to the first embodiment includes a belt main body 1. As shown in FIG. 1, the belt body 1 includes a core layer 11 and a front cover rubber layer (rubber layer) 12 and a back cover rubber layer (rubber layer) 13 laminated on both sides of the core layer 11. It is provided.

  The core layer 11 bears a tension applied to the belt due to a transported object or running resistance. Specifically, for example, the one made of a canvas 11a and an adhesive rubber 11c as shown in FIG. 1 and the one made of a steel cord 11b and an adhesive rubber 11c (not shown) are exemplified. As the canvas, polyester fiber, nylon (polyamide) fiber, aramid fiber, or the like is used. When a canvas is used, bonding is performed using RFL (resorcinol / formalin / latex) or the like. When a steel cord is used, the steel cord is treated by plating or the like. Thereafter, the core layer 11 is vulcanized and bonded to the front cover rubber layer 12 and the back cover rubber layer 13 together with the adhesive rubber 11c interposed between both surfaces of the canvas 11a or between the arrangement and both surfaces of the steel cord 11b.

  The cover rubber layers 12 and 13 are formed of a rubber composition obtained by mixing and kneading an uncrosslinked rubber composition obtained by mixing and kneading various compounding agents with a rubber component, and then heating and pressurizing and crosslinking with a crosslinking agent. The rubber composition forming the front cover rubber layer 12 and the back cover rubber layer 13 contains the cellulosic fine fibers 14. The inclusion of the cellulosic fine fibers 14 imparts excellent strength to the conveyor belt V.

  Examples of the rubber component include SBR (styrene / butadiene rubber), NR (natural rubber), BR (butadiene rubber), NBR (nitrile / butadiene rubber), CR (chloroprene rubber), and EPR (ethylene / propylene rubber). No. The rubber component is preferably one or more of these.

  The cellulosic fine fiber 14 is a fiber material derived from cellulosic fine fiber composed of a skeletal component of a plant cell wall obtained by finely loosening plant fiber. Examples of the raw material plant of the cellulosic fine fiber 14 include wood, bamboo, rice (rice straw), potato, sugarcane (bagasse), aquatic plants, seaweed, and the like. Of these, wood is preferred.

  The cellulosic fine fibers 14 may be cellulose fine fibers themselves, or may be hydrophobic treated cellulose fine fibers. Further, as the cellulosic fine fibers 14, the cellulosic fine fibers themselves and the hydrophobized cellulose fine fibers may be used in combination. From the viewpoint of dispersibility, the cellulosic fine fibers 14 preferably include hydrophobized cellulose fine fibers. Examples of the hydrophobized cellulose fine fibers include cellulose fine fibers in which some or all of the hydroxyl groups of cellulose have been substituted with hydrophobic groups, and cellulose fine fibers that have been hydrophobized and surface-treated with a surface treatment agent.

  Examples of the hydrophobization for obtaining cellulose fine fibers in which some or all of the hydroxyl groups of the cellulose are substituted with a hydrophobic group include esterification (acylation) (alkyl esterification, complex esterification, β-ketoesterification, etc.). ), Alkylation, tosylation, epoxidation, arylation and the like. Of these, esterification is preferred. Specifically, in the esterified hydrophobized cellulose fine fibers, a part or all of the hydroxyl groups of the cellulose is a carboxylic acid such as acetic acid, acetic anhydride, propionic acid, butyric acid, or a halide thereof (particularly chloride). Cellulose fine fibers acylated by Examples of the surface treatment agent for obtaining the cellulose fine fibers which have been hydrophobized by the surface treatment agent include silane coupling agents.

  From the viewpoint of improving the strength of the conveyor belt V, the cellulosic fine fibers 14 preferably have a wide fiber diameter distribution. The distribution range of the fiber diameter of the cellulosic fine fibers 14 preferably includes 3 to 500 nm from the viewpoint of improving the strength of the conveyor belt V.

  The average fiber diameter of the cellulosic fine fibers 14 contained in the rubber compositions forming the cover rubber layers 12 and 13 is preferably 10 nm or more and 200 nm or less from the viewpoint of improving the strength of the conveyor belt V.

  The distribution of the fiber diameter of the cellulosic fine fibers 14 was determined by freeze-pulverizing a sample of the rubber composition for forming the cover rubber layers 12 and 13 and then observing the cross section with a transmission electron microscope (TEM). The cell diameter is determined by arbitrarily selecting the cellulosic fine fiber 14 and measuring the fiber diameter based on the measurement result. The average fiber diameter of the cellulosic fine fibers 14 is determined as the number average of the fiber diameters of the 50 arbitrarily selected cellulosic fine fibers 14.

  The cellulosic fine fibers 14 may be those having a high aspect ratio produced by mechanical defibration means or those produced by chemical defibration means. Further, as the cellulosic fine fiber, a fiber produced by a mechanical fibrillation means and a fiber produced by a chemical fibrillation means may be used in combination. Examples of the defibrating device used for the mechanical defibrating means include a kneader such as a twin-screw kneader, a high-pressure homogenizer, a grinder, a bead mill, and the like. Examples of the treatment used for the chemical fibrillation means include an acid hydrolysis treatment and the like.

  The orientation direction of the cellulosic fine fibers 14 in the rubber composition forming the cover rubber layers 12 and 13 may be either the belt width direction or the belt length direction.

  From the viewpoint of improving the strength of the conveyor belt V, the content of the cellulosic fine fibers 14 in the rubber compositions forming the cover rubber layers 12 and 13 is preferably at least 1 part by mass, more preferably at least 1 part by mass. It is preferably at least 3 parts by mass, more preferably at least 5 parts by mass, and preferably at most 30 parts by mass, more preferably at most 20 parts by mass, even more preferably at most 10 parts by mass.

  Examples of the compounding agent to be added to the rubber composition forming the cover rubber layers 12 and 13 include a reinforcing agent, an oil, a processing aid, a vulcanization accelerator, an antioxidant, a vulcanization accelerator and a crosslinking agent. Can be

  Examples of the reinforcing agent include carbon black and silica. Examples of carbon black include channel black; furnace blacks such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234; thermal blacks such as FT and MT; acetylene Black and the like. The reinforcing agent may be composed of a single type, or may be composed of a plurality of types.

  For example, it is common to add carbon black as a reinforcing agent to a rubber product. However, according to the conveyor belt V according to the first embodiment, the cover rubber layers 12 and 13 include the cellulosic fine fibers 14. Since the strength of the cover rubber layers 12 and 13 is improved, the amount of carbon black added to the cover rubber layers 12 and 13 can be greatly reduced or no carbon black can be added.

  Therefore, the rubber composition forming the cover rubber layers 12 and 13 may be configured to contain carbon black as a reinforcing agent. In this case, the content of carbon black is set to 100 parts by mass of the rubber component. On the other hand, it is preferably at least 1 part by mass, more preferably at least 5 parts by mass, and preferably at most 20 parts by mass, more preferably at most 10 parts by mass. The content of carbon black is preferably the same as or higher than the content of cellulosic fine fibers. The ratio of the content of carbon black to the content of cellulosic fine fibers (content of carbon black / content of cellulosic fine fibers) is preferably 1 or more, more preferably 5 or more, and preferably 50 or more. Or less, more preferably 40 or less.

  On the other hand, the rubber composition forming the cover rubber layers 12 and 13 may have a configuration not containing carbon black as a reinforcing agent. In this case, the content of the cellulosic fine fibers is preferably 10 parts by mass or more based on 100 parts by mass of the rubber component.

  Examples of oils include petroleum softeners, mineral oils such as paraffin wax, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, falling raw oil, wood wax, rosin, pine And vegetable oils such as oils. The oil may be composed of a single type or a plurality of types. The content of the oil is, for example, 5 to 20 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition.

  Examples of the processing aid include stearic acid, polyethylene wax, and metal salts of fatty acids. The processing aid may be composed of a single type, or may be composed of a plurality of types. The content of the processing aid is, for example, 0.5 to 4 parts by mass based on 100 parts by mass of the rubber component of the rubber composition.

  Examples of the vulcanization accelerator include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids and derivatives thereof. The vulcanization accelerating aid may be composed of a single type, or may be composed of a plurality of types. The content of the vulcanization accelerator is, for example, 3 to 15 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition.

  Examples of the vulcanization accelerator include thiazole (eg, MBT, MBTS, etc.), thiuram (eg, TT, TRA, etc.), sulfenamide (eg, CZ, etc.), and dithiocarbamate (eg, BZ-P). And the like. The vulcanization accelerator may be composed of a single type, or may be composed of a plurality of types. The content of the vulcanization accelerator is, for example, 0.5 to 5 parts by mass based on 100 parts by mass of the rubber component of the rubber composition.

  Crosslinking agents include sulfur and organic peroxides. As the crosslinking agent, sulfur may be blended, or an organic peroxide may be blended, or both of them may be used in combination. The compounding amount of the crosslinking agent is, for example, 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component of the rubber composition in the case of sulfur, and 100 parts by mass of the rubber component in the case of an organic peroxide in the case of organic peroxide. For example, 1 to 5 parts by mass.

  According to the conveyor belt V according to the first embodiment having the above-described configuration, the rubber composition forming the cover rubber layers 12 and 13 contains the cellulosic microfibers 14, thereby imparting excellent strength to the conveyor belt V. can do.

  Since the strength of the cover rubber layers 12 and 13 can be controlled by the content of the cellulosic fine fibers 14 in the cover rubber layers 12 and 13, the desired strength can be adjusted by adjusting the content. Can be provided.

Further, the wear resistance of the cover rubber layers 12 and 13 can be improved. The abrasion resistance is a wear amount based on JIS K 6254 DIN abrasion test, preferably 200 mm ³ or less, more preferably 150 mm ³ or less, and still more preferably 100 mm ³ or less.

Further, since the cellulosic fine fibers 14 have a lower specific gravity than carbon black and silica as conventional reinforcing agents, the cover rubber layers 12 and 13 of the conveyor belt V according to the first embodiment are more than conventional ones. Is also light in specific gravity. Therefore, the weight of the conveyor belt can be reduced. The specific gravity of the cover rubber layers 12 and 13 is preferably 1.1 g / cm ³ or less.

  Further, by containing the cellulosic fine fibers 14, the elastic modulus of the cover rubber layers 12, 13 is greatly improved as compared with the conventional reinforcing agents such as carbon black and silica. Therefore, even if the addition amount of the reinforcing agent is reduced, the cover rubber layers 12 and 13 having the same performance can be obtained, so that the thickness of the conveyor belt V can be reduced. The elastic modulus of the cover rubber layers 12, 13 is a storage elastic modulus E '(MPa) based on JIS K 6394, and is preferably 3 MPa or more, and more preferably 30 MPa or less.

  In addition, the cover rubber layers 12 and 13 containing the cellulosic fine fibers 14 have a small loss tangent tan δ, and therefore have low running resistance. The loss tangent tan δ of the cover rubber layers 12, 13 obtained based on JIS K 6394 is preferably 0.1 or less at an ambient temperature of 20 ° C.

  Thus, in the conveyor belt V provided with the cover rubber layers 12 and 13 containing the cellulosic fine fibers 14, the weight and thickness of the conveyor belt can be reduced, and the running resistance can be reduced. Power consumption and energy saving can be achieved.

  Further, by using the cellulosic fine fibers 14 as the reinforcing agent, the amount of the reinforcing agent can be reduced as compared with the conventional reinforcing agent, so that the deterioration of the workability of the conveyor belt V can be suppressed. In addition, in the conventional conveyor belt, a reinforcing cloth is usually applied for reinforcement, but in the conveyor belt V according to the first embodiment, the reinforcing cloth is not required.

(Conveyor belt manufacturing method)
Next, a manufacturing process of the conveyor belt will be described. The manufacturing process of the conveyor belt includes a core layer forming step, a cover rubber layer forming step, and a vulcanizing step.

<Core layer forming step>
After the strip-shaped canvas wound in a roll shape is sequentially pulled out from the end, an adhesive rubber is applied or infiltrated, or an RFL (resorcin-formalin-latex) treatment is performed, and then the roll-shaped fabric is rewound into a roll shape again.

<Cover rubber layer forming step>
In this manner, an unvulcanized belt molded body is formed using the canvas subjected to the treatment for increasing the adhesiveness as the core layer 11. Specifically, while pulling out the canvas from the roll, unvulcanized rubber sheets are laminated on both the front and back sides of the canvas, and unvulcanized ear rubber material is attached to both ends in the width direction, and excess parts of both ears are cut By doing so, an unvulcanized belt molded body having a predetermined width and thickness is obtained. The unvulcanized belt formed body thus formed is sequentially wound around a drum. Usually, the thickness of the unvulcanized rubber sheet located on the transport surface side is greater than that of the unvulcanized rubber sheet located on the non-transport surface.

-Uncrosslinked rubber sheets 12 ', 13'-
The uncrosslinked rubber sheet used for the cover rubber layers 12 and 13 is produced as follows. That is, various rubber compounding agents are blended with the rubber component, kneaded with a kneading machine such as a kneader or a Banbury mixer, and the obtained uncrosslinked rubber composition is formed into a sheet by calendering or the like to form an uncrosslinked rubber sheet 12. ', 13' are prepared.

  In the present embodiment, the cellulosic fine fibers 14 are contained in advance in the rubber compositions of the cover rubber layers 12 and 13 or on their surfaces. The cellulosic fine fibers 14 may be contained in both the cover rubber layers 12 and 13, or the cellulosic fine fibers 14 may be contained only in one of the layers.

  As a specific method for incorporating the cellulosic fine fibers 14 into the surfaces of the cover rubber layers 12 and 13, when producing the rubber composition for the cover rubber layer, the cellulosic fine fibers 14 are kneaded with the rubber composition. After forming the unvulcanized belt molded body 1 ′ by laminating the cover rubber layers 12 and 13 above and below the core layer 11 using a rubber composition containing no cellulosic fine fibers 14, A method of adhering the cellulosic fine fibers 14 to the surfaces of the cover rubber layers 12 and 13 is exemplified.

  When the cellulosic fine fibers 14 are kneaded in the rubber composition, the following method is used.

  First, the cellulosic fine fibers 14 are added to the masticated rubber component and kneaded to be dispersed.

  Here, as a method of dispersing the cellulosic fine fibers 14 in the rubber component, for example, a dispersion (gel) obtained by dispersing the cellulosic fine fibers 14 in water is added to the rubber component kneaded with an open roll. A method of vaporizing water while kneading them, a method of mixing a dispersion (gel) in which the cellulosic fine fibers 14 are dispersed in water and a rubber latex to vaporize water. A method in which a rubber masterbatch is added to a masticated rubber component, a dispersion in which the hydrophobized cellulosic fine fibers 14 are dispersed in a solvent, and a solution in which the rubber component is dissolved in a solvent are mixed to form a solvent. A method in which a cellulose-based fine fiber / rubber masterbatch obtained by vaporization is added to a masticated rubber component, a dispersion in which the cellulose-based fine fibers 14 are dispersed in water ( What was triturated Le) lyophilized, how to put into a rubber component is masticated, methods and the like to introduce cellulosic fines 14 that hydrophobicized rubber component is masticated.

  Note that a surfactant may be further added to such a dispersion (gel) or master batch. Thereby, the compatibility between the cellulosic fine fibers 14 and the rubber component is improved.

  Next, while kneading the rubber component and the cellulosic fine fibers 14, various compounding agents are added and kneading is continued.

  Then, the obtained rubber composition is formed into a sheet by calendering or the like, thereby producing rubber sheets 12 'and 13'.

  As described above, when the cellulosic fine fibers 14 are kneaded at the time of compounding the rubber composition, from the viewpoint of improving the strength of the conveyor belt V, the ratio of the cellulosic fine fibers 14 in the rubber composition is 1 to 25. It is preferable that the mixture is kneaded so as to have a mass%, so that the cellulosic fine fibers 14 are contained on both the surface and the inside of the cover rubber layer.

Next, as a method of adhering the cellulosic fine fibers 14 to the surfaces of the cover rubber layers 12 and 13, a method of physically applying the cellulosic fine fibers 14, a method of adhering by using static electricity, and the like are used. be able to. In this case, from the viewpoint of improving the strength of the conveyor belt V, it is preferable to adhere the cellulosic fine fibers 14 so that the adhesion amount is 1 to 300 g / m ² per unit surface area of the cover rubber layer.

<Vulcanization process>
In the vulcanization step, the unvulcanized belt compact is vulcanized to form a conveyor belt V. The vulcanizing machine used in the vulcanizing process is equipped with a pair of upper and lower hot plates, in which an unvulcanized belt molded body is charged and pressed, and vulcanization is performed by applying heat and pressure for a certain period of time. To form a conveyor belt V having a desired width and thickness. For example, vulcanization is performed at a temperature of 150 ° C. to 160 ° C. and a surface pressure of 20 kg / cm ² for 15 minutes to 20 minutes.

[Embodiment 2]
Hereinafter, other embodiments according to the present invention will be described in detail. In the description of these embodiments, the same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description will be omitted.

(Conveyor belt for steeply inclined conveyance)
As shown in FIG. 2, the steeply conveyed conveyor belt V ′ according to the present embodiment includes a belt structure 2. The belt structure 2 includes a belt body 1, a pair of corrugated waves 22 in a wave shape in a plan view standing upright in the vicinity of both side edges on the belt body 1, and a predetermined interval between the pair of corrugated waves 22. It has a number of horizontal rails 23 provided in the circumferential direction of the belt main body 1.

  The steeply conveyed conveyor belt V 'can be used as a means for conveying a conveyed material such as sand, earth and sand, crushed stone, or a lump from a low place to a high place. In this case, the conveyed goods are loaded in a box including a portion surrounded by the belt main body 1, the corrugated rails 22 on both sides, and two adjacent horizontal rails 23. In the above description, the horizontal rail 23 is provided at an angle. However, the horizontal rail 23 may be formed at right angles to the belt main body 1 depending on the type of the conveyed object.

  The corrugated rail 22 is mainly for preventing the conveyed article from dropping to the side. Further, since the corrugated rail 22 is bent in a wave shape in a plan view, the corrugated rail 22 has a large lateral rigidity, so that even when a heavy conveyed object is loaded, it can be effectively prevented from falling off from the side part. The horizontal rail 23 is mainly for preventing the conveyed object from falling down.

  The corrugated rail 22 and the horizontal rail 23 have a rubber layer 22a and a rubber layer 23a, respectively. The rubber layers 22a and 23a are formed of a rubber composition containing the same rubber components and compounding agents as the cover rubber layers 12 and 13 of the belt body 1. Further, the corrugated rail 22 and the horizontal rail 23 may be configured to include the core layers 22b and 23b laminated on the rubber layers 22a and 23a, or may be formed only of the rubber layers 22a and 23a without the core layers 22b and 23b. It may be configured. The core layers 22b and 23b can have the same configuration as the core layer 11 described above.

  The corrugated beam 22 and the horizontal beam 23 can contain the cellulosic fine fibers 14 as in the case of the cover rubber layers 12 and 13 of the belt body 1. In the steeply conveyed conveyor belt V ′ according to the present embodiment, the rubber layer provided on at least one of the belt body 1, the corrugated rail 22 and the horizontal rail 23 contains the cellulosic fine fibers 14.

  According to the steeply conveyed conveyor belt V ′ according to the second embodiment, the cover rubber layers 12 and 13 and the rubber layers 22 a and 23 a contain the cellulose-based fine fibers 14, so that the conveyor belt has excellent strength. Can be granted.

  By using the rubber layers 12, 13, 22a and 23a containing the cellulosic fine fibers 14, the breaking elongation of the rubber layers is increased as compared with the conventional one. In general, in a high-strength rubber product, the elongation at break is reduced, but the rubber layers 12, 13, 22a, and 23a containing the cellulosic fine fibers 14 are excellent in strength and workability. The breaking elongation of the rubber layers 12, 13, 22a and 23a is preferably 450% or more.

  In addition, by using the rubber layers 12, 13, 22a, and 23a containing the cellulosic fine fibers 14, the bending fatigue resistance of the rubber layers is improved, and the durability of the conveyor belt V 'is improved. The bending fatigue resistance of the rubber layers 12, 13, 22a and 23a is a crack length (mm) at the time of bending 50,000 times according to JIS K 6260, and is preferably 25 mm or less.

(Method of manufacturing a conveyor belt for steeply inclined conveyance)
The rubber layers 22a and 23a of the corrugated rail 22 and the horizontal rail 23 can be manufactured by the same method as the cover rubber layers 12 and 13 according to the first embodiment. Further, the method for incorporating the cellulosic fine fibers 14 into the rubber layers 22a and 23a of the corrugated rail 22 or the horizontal rail 23 is also as described above.

  When the core layers 22b and 23b are provided, a belt molded body is manufactured as described above, and after the pressure vulcanization, the molded body is cut into a corrugated beam 22 or a horizontal beam 23. When the corrugated rail 22 is vulcanized under pressure, vulcanization is performed using a vulcanizer equipped with a corrugated hot plate. When the core layers 22b and 23b are not provided, a belt molded body including only the rubber layers 22a and 23a is manufactured, and pressure vulcanization is performed as described above.

[About the belt body of the conveyor belt]
As Examples 1 to 5 and Comparative Example 1, rubber sheets used for the cover rubber layers 12 and 13 of the belt main body 1 of the conveyor belt V according to the first embodiment and the steeply-conveying conveyor belt V ′ according to the second embodiment. Was prepared. Table 1 shows the composition of the rubber sheet and the results of various tests.

(Example 1)
-Cellulose dispersion gel-
A dispersion in which powdered cellulose (trade name: KC Floc W-50GK, manufactured by Nippon Paper Industries) is dispersed in water is prepared, and the dispersions are collided with each other using a high-pressure homogenizer to dissolve the powdered cellulose into cellulose fine fibers. A fine gel was obtained by dispersing cellulose fine fibers in water (hereinafter referred to as “cellulose dispersed gel”). Therefore, the cellulose fine fibers are produced by mechanical defibration means and have not been subjected to a hydrophobic treatment.

-Rubber sheet-
As shown in Table 1, as for the rubber sheet, 100 parts by mass of NBR rubber (product number: N230S, manufactured by JSR Corporation) was kneaded by Mixtron BB180 manufactured by Kobe Steel, and the cellulose dispersed gel was mixed with cellulose fine fiber. After adding so that the content might be 1 part by mass, the mixture was further kneaded to evaporate water. Then, 10 parts by mass of carbon black HAF (product number: Seast 3, manufactured by Tokai Carbon Co., Ltd.) was added as a reinforcing agent, and 7 parts by mass of DBP (product number: DBP, manufactured by Miyako Chemical Co., Ltd.) was added as an oil and further kneaded. Finally, 2 parts by weight of stearic acid as a processing aid (product number: beads stearic acid Tsubaki, manufactured by Sanyu Industrial Co., Ltd.), zinc oxide III as a vulcanization accelerator (product number: Zinhua No. 3A, Mitsui Mining & Smelting) 5 parts by mass, an antioxidant (product number: Nocrack 6C, Nocrack 224, Sunnoc Nocrack AW-N, manufactured by Ouchi Shinko Chemical Co., Ltd.) and 3 parts by mass, and a vulcanization accelerator (product number: Noxeller NS) -F, manufactured by Ouchi Shinko Chemical Co., Ltd.), and kneaded with a Banbury mixer. After kneading the rubber into a sheet by TSR, 2.5 parts by mass of sulfur (product number: Seimi OT, manufactured by Rubber Industrial Materials Co., Ltd.) as a cross-linking agent is charged by a mill blender, and the rubber sheet (thickness) 10 mm).

(Examples 2 to 5 and Comparative Example 1)
As shown in Table 1, Examples 2 to 5 differ from Example 1 in the amount of cellulose fine fiber and the amount of carbon black as a reinforcing agent, respectively. In particular, Examples 3 to 5 do not contain carbon black. Comparative Example 1 does not contain cellulose fine fibers.

[About Wave Pier]
As Examples 6 to 10 and Comparative Example 2, rubber sheets used as the rubber layer 22a of the corrugated rail 22 according to Embodiment 2 were produced. Table 2 shows the composition of the rubber sheet and the results of various tests.

(Example 6)
As shown in Table 2, the point that NR rubber (part number: SVR-L, manufactured by Mitomi Shoten Co., Ltd.) and recycled rubber (part number: TYREC-T-1, manufactured by Sawano Shoten Co., Ltd.) were used as rubber components. Except for this, a rubber sheet was manufactured in the same manner as in Example 1.

(Examples 7 to 10 and Comparative Example 2)
As shown in Table 2, Examples 7 to 10 are different from Example 6 in the amount of cellulose fine fiber and the amount of carbon black as a reinforcing agent, respectively. In particular, Examples 8 to 10 do not contain carbon black. Comparative Example 2 does not contain fine cellulose fibers.

[About the crossbar]
As Examples 11 to 15 and Comparative Examples 3 to 5, rubber sheets used as the rubber layer 23a of the horizontal rail 23 according to Embodiment 2 were produced. Table 3 shows the composition of the rubber sheet and the results of various tests.

(Example 11)
Except for using SBR rubber (product number: SBR1712, manufactured by JSR Corporation) and NR rubber (product number: SVR-L, manufactured by Mitomi Shoten Co., Ltd.) as the rubber components, the rubber was manufactured in the same manner as in Example 1. A sheet was manufactured.

(Examples 12 to 15 and Comparative Examples 3 to 5)
As shown in Table 3, Examples 12 to 15 differ from Example 11 in the amount of cellulose fine fiber and the amount of carbon black as a reinforcing agent, respectively. In particular, Examples 13 to 15 do not contain carbon black. Comparative Examples 3 to 5 did not contain cellulose fine fibers, Comparative Example 3 contained only carbon black, Comparative Example 4 contained nylon short fibers instead of cellulose fine fibers, and did not contain carbon black. Has a configuration including both nylon short fibers and carbon black.

<Test evaluation method>
(Average fiber diameter / fiber diameter distribution)
In Example 2, after the sample of the crosslinked rubber sheet was freeze-pulverized, its cross section was observed with a transmission electron microscope (TEM), and 50 fibers were arbitrarily selected to measure the fiber diameter. The number average was determined and defined as the average fiber diameter.

  Further, with respect to the rubber sheet sample of Example 2, the maximum value and the minimum value of the fiber diameter among 50 cellulose fine fibers were determined.

(specific gravity)
The specific gravity was determined by measuring the density D (g / cm ³ ) based on JIS K6268. In Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative values were evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.

(Energy saving)
Energy saving was determined by measuring the loss tangent tan δ based on JIS K 6394. As a test machine, "FT-Rheospectra DVE-V4" manufactured by Rheology Co., Ltd. was used. The test conditions were a frequency of 1.0 Hz, a temperature of 25 ° C., a sample thickness of 2.0 mm, a sample length of 8.00 mm, and a sample width of 5 mm. The measured value of the loss tangent tan δ was the maximum value when the sample strain amount with respect to the length was measured in the range of 0.1 to 10%. In Examples 1 to 5, the reciprocal (1 / tan δ) of the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100 and evaluated by the relative value of 1 / tan δ. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 evaluated 1 / tan δ obtained for the rubber sheet of Comparative Example 3 as 100, and evaluated the relative values thereof.

(Elastic modulus)
The elastic modulus was determined by measuring the storage elastic modulus E ′ (MPa) based on JIS K 6394. In Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative values were evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.

(Weatherability)
For weather resistance, a crack state was observed based on JIS K 6259. The number of cracks on the entire rubber sheet surface in the photographing range was counted for an optical microscope photograph of the rubber sheet surface at a predetermined magnification. In Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative values were evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.

(Wear resistance)
The test for abrasion resistance was based on JIS K 6264 (1993) “Method for testing wear of vulcanized rubber”. As a test machine, a DIN abrasion tester “Type 584c” (trade name) manufactured by KARL FRANK GMBH was used. The test piece had a diameter of 16 mm and a thickness of 6.0 mm. In addition, in Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative value was evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.

(Crack resistance)
The crack resistance was determined by measuring the number of times of crack occurrence in a dematcher method based on JIS K 6260. In Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative values were evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.

(Impact resistance (chip cutting property))
Impact resistance (tip-cutting property) was measured by the following method. That is, a needle mountain block in which three iron quenching pins each having a diameter of 5 mm are embedded in each surface of an iron hexahedron made of an equilateral triangle having a size of 45 mm, and an inner surface of a cylindrical iron container having an inner diameter of 155 mm and a height of 177 mm. Then, a sample rubber of 120 mm × 82 mm × 5 mm (thickness) whose mass has been measured in advance is fixed in a drum of six pieces by cross-linking molding using a molding frame. After that, the inside temperature of the drum was kept at about 70 ° C. using an infrared lamp of 100 V × 200 W for the drum, and the drum was rotated at a speed of 36 rpm for 7 days. Then, the needle mountain block was taken out, and the sample rubber was removed from the drum and adhered. The remaining rubber dust was completely removed, the mass was measured, and the volume was converted from the specific gravity to the volume, and the volume change rate was determined by the following equation (1). In Examples 1 to 5, the measured value obtained for the rubber sheet of Comparative Example 1 was set to 100, and the relative values were evaluated. Similarly, in Examples 6 to 10, Comparative Examples 2 and Examples 11 to 15 and Comparative Examples 4 and 5 were evaluated based on the relative values, with the measured value obtained for the rubber sheet of Comparative Example 3 being 100.
｛(Pre-volume)-(pre-volume) ÷ × 100 (1)

(Elongation at break)
The elongation at break was determined by measuring Eb (%) based on JIS K6251. In Examples 11 to 15 and Comparative Examples 4 and 5, the measured value obtained for the rubber sheet of Comparative Example 3 was set to 100, and the relative values were evaluated.

(Bending fatigue resistance)
The bending fatigue resistance was determined by measuring the crack length (mm) at the time of bending 50,000 times in the dematcher method based on JIS K 6260. In Examples 11 to 15 and Comparative Examples 4 and 5, the reciprocal of the measured value obtained for the rubber sheet of Comparative Example 3 was set to 100, and the relative value of the reciprocal of the measured value was evaluated.

<Test evaluation results>
[About the belt body of the conveyor belt]
According to Table 1, for the rubber sheet of Example 2, the average fiber diameter of the cellulose fine fibers was 90 nm. In the rubber sheet of Example 2, the minimum value and the maximum value of the fiber diameter of the cellulose fine fiber were 3 nm and 150 nm, respectively.

  According to Table 1, since the specific gravity of the rubber sheets of Examples 1 to 5 is lower than that of Comparative Example 1, the weight can be reduced.

  Further, compared to Comparative Example 1, the rubber sheets of Examples 1 to 5 show improvement in energy saving. In particular, when Examples 1 to 5 are compared with each other, as the content of the cellulose fine fiber increases, the energy saving property is improved.

  In addition, the elastic modulus is improved in the rubber sheets of Examples 1 to 5 as compared with Comparative Example 1. In particular, when Examples 1 to 5 are compared, the elastic modulus increases as the content of the cellulose fine fiber increases. It has improved significantly.

  Further, it can be seen that the weather resistance of the rubber sheets of Examples 1 to 5 is more suppressed than that of Comparative Example 1 from the occurrence of cracks. In particular, comparing Examples 1 to 5, it can be seen that Examples 3 to 5 containing no carbon black have significantly improved weather resistance as compared with Examples 1 and 2 containing carbon black.

  It can be seen that the abrasion resistance is improved in the rubber sheets of Examples 1 to 5 as compared with Comparative Example 1.

  It can be seen that the crack resistance is significantly improved in the rubber sheets of Examples 1 to 5 as compared with Comparative Example 1. In particular, comparing Examples 1 to 5, it can be seen that Examples 3 to 5, which do not contain carbon black, have significantly improved crack resistance as compared with Examples 1, 2 which contain carbon black.

  It can be seen that the impact resistance of the rubber sheets of Examples 1 to 5 is significantly improved as compared with Comparative Example 1. In particular, comparing Examples 1 to 5, it can be seen that Examples 3 to 5, which do not contain carbon black, have significantly improved impact resistance as compared with Examples 1, 2 which contain carbon black.

[About Wave Pier]
According to Table 2, since the specific gravity of the rubber sheets of Examples 6 to 10 is lower than that of Comparative Example 2, the weight can be reduced.

  In addition, energy saving is improved in the rubber sheets of Examples 6 to 10 as compared with Comparative Example 2.

  In addition, the elastic modulus is improved in the rubber sheets of Examples 6 to 10 as compared with Comparative Example 2, and particularly as compared with Examples 6 to 10, the elastic modulus increases as the content of the cellulose fine fiber increases. It has improved significantly.

  Further, it can be seen that the weather resistance of the rubber sheets of Examples 6 to 10 is more suppressed than that of Comparative Example 2 from the occurrence of cracks. In particular, comparing Examples 6 to 10, it can be seen that Examples 8 to 10 which do not contain carbon black have significantly improved weather resistance as compared with Examples 6 and 7 which contain carbon black.

  It can be seen that the wear resistance of the rubber sheets of Examples 6 to 10 is improved as compared with Comparative Example 2. Further, comparing Examples 6 to 10, the wear resistance is improved as the content of the cellulose fine fiber is increased.

  It can be seen that the crack resistance is significantly improved in the rubber sheets of Examples 6 to 10 as compared with Comparative Example 2. In particular, comparing Examples 6 to 10, it can be seen that Examples 8 to 10 that do not contain carbon black have significantly improved crack resistance as compared with Examples 6 and 7 that contain carbon black.

  It can be seen that the impact resistance is significantly improved in the rubber sheets of Examples 6 to 10 as compared with Comparative Example 2. In particular, comparing Examples 6 to 10, it can be seen that Examples 8 to 10 which do not contain carbon black have significantly improved impact resistance as compared with Examples 6 and 7 which contain carbon black.

[About the crossbar]
According to Table 3, since the specific gravity of the rubber sheets of Examples 11 to 15 is lower than that of Comparative Example 3, the weight can be reduced.

  In addition, energy savings are improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. In particular, when Examples 11 to 15 are compared, as the content of the cellulose fine fiber increases, the improvement in energy saving can be seen.

  Further, the elastic modulus is improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3, and particularly as compared with Examples 11 to 15, as the content of the cellulose fine fiber increases, the elastic modulus is It has improved significantly.

  Further, it can be seen that the weather resistance of the rubber sheets of Examples 11 to 15 is less suppressed than that of Comparative Example 3. In particular, comparing Examples 11 to 15, it can be seen that Examples 13 to 15, which do not contain carbon black, have significantly improved weather resistance as compared with Examples 11, 12 which contain carbon black.

  It can be seen that the abrasion resistance is improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. Moreover, when Examples 11 to 15 are compared, the wear resistance is improved as the content of the cellulose fine fiber is increased.

  It can be seen that the crack resistance is significantly improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. In particular, comparing Examples 11 to 15, it can be seen that Examples 13 to 15 which do not contain carbon black have significantly improved crack resistance as compared with Examples 11 and 12 which contain carbon black.

  It can be seen that the impact resistance is significantly improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. In particular, when comparing Examples 11 to 15, it can be seen that Examples 13 to 15 which do not contain carbon black have greatly improved impact resistance as compared with Examples 11 and 12 which contain carbon black.

  It can be seen that the elongation at break is increased in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. Also, comparing Examples 11 to 15, it can be seen that the elongation at break increases as the content of the cellulose fine fibers increases.

  It can be seen that the bending fatigue resistance is improved in the rubber sheets of Examples 11 to 15 as compared with Comparative Example 3. Further, comparing Examples 11 to 15, it can be seen that as the content of the cellulose fine fiber increases, the bending fatigue resistance improves.

  Comparative Example 4 contained only nylon short fibers instead of cellulose fine fibers and carbon black, but had specific gravity, abrasion resistance, crack resistance, and impact resistance. Similarly, the numerical values are improved, but it can be seen that the breaking elongation and the bending fatigue resistance are significantly inferior to those of Comparative Example 3.

  Comparative Example 5 contained carbon black and nylon staple fibers instead of cellulose fine fibers, but exhibited abrasion resistance, crack resistance, and impact resistance, similar to those in Examples 11 to 15. However, it can be seen that the specific gravity is inferior to Comparative Example 3, and the elongation at break and the flex fatigue resistance are significantly inferior to Comparative Example 3.

  The invention is useful in the conveyor belt art.

V Conveyor belt V 'Conveyor belt for steeply inclined conveyance (Conveyor belt)
1 Belt body 12 Front cover rubber layer (rubber layer)
13 Back cover rubber layer (rubber layer)
22 Wave rail 22a Rubber layer 23 Horizontal rail 23a Rubber layer

Claims (4)

A conveyor belt having a belt body with a rubber layer,
A conveyor belt wherein the rubber layer contains cellulosic fine fibers. The conveyor belt according to claim 1,
It further has a wave cross and a horizontal cross,
A conveyor belt, wherein at least one of the corrugated crosspiece and the horizontal crosspiece has a rubber layer containing cellulosic fine fibers. The conveyor belt according to claim 1 or 2,
A conveyor belt in which the distribution range of the fiber diameter of the cellulosic fine fibers is from 3 to 500 nm. The conveyor belt according to any one of claims 1 to 3,
A conveyor belt wherein the content of the cellulosic fine fibers is 1 to 25 parts by mass with respect to 100 parts by mass of the rubber component of the rubber layer.

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