JP4602531B2 - Conveyor belt and method for joining the conveyor belt - Google Patents

Description

【００３２】
【表２】

【００３３】
［実施例１］
線状心材に直径６．３ｍｍのスチールコードを用い、上記表１の配合１に記載の接着ゴム層用未加硫ゴム組成物と表２の配合３に記載のカバーゴム層用未加硫ゴム組成物とを用いて、ＪＩＳＫ６３６９「スチールコードコンベヤベルト」に記載の図６に従って実施例１の引張試験用試験片を作製した。
【００３４】
［実施例２］
カバーゴム層用未加硫ゴム組成物として表２の配合４に記載のものを用いた以外は上記実施例１と同様にして実施例２の引張試験用試験片を作製した。
【００３５】
［実施例３］
接着ゴム層用未加硫ゴム組成物として表１の配合２に記載のものを用いた以外は上記実施例１と同様にして実施例３の引張試験用試験片を作製した。
【００３６】
［比較例］
接着ゴム層用未加硫ゴム組成物として表１の配合２に記載のものを用い、カバーゴム層用未加硫ゴム組成物として表２の配合４に記載のものを用いた以外は上記実施例１と同様にして比較例の引張試験用試験片を作製した。
【００３７】
［特性の評価］
上記実施例１〜３及び比較例の引張試験用試験片を用いて動的疲労破壊試験を行い、耐疲労性を評価した。この耐疲労性の評価は、サーボパルサーを用いて試験片に繰り返し引張応力を負荷する動的疲労破壊試験を施し、破壊に至るまでの回数によって評価する。その結果を下記の表３に示した。なお、表３の耐疲労性の評価欄の数は、比較例の破壊回数を基準（１）とした比である。
【００３８】
【表３】

【００３９】
上記表３に示すように、従来のコンベヤベルトと同様の比較例の引張試験用試験片と比較して、接着ゴム層及びカバーゴム層にナイロン短繊維を分散含有する実施例１の引張試験用試験片が格段に高い耐疲労性を示し、接着ゴム層とカバーゴム層の一方にナイロン短繊維を分散含有する実施例２及び実施例３の引張試験用試験片も耐疲労性が向上している。また、実施例２と実施例３の引張試験用試験片を比較すると、接着ゴム層にナイロン短繊維を分散含有した実施例２の引張試験用試験片の方が、カバーゴム層にナイロン短繊維を分散含有した実施例３の引張試験用試験片よりも高い耐疲労性を示した。
【００４０】
【発明の効果】
以上説明したように、本発明のコンベヤベルト及びこのコンベヤベルトの接合方法によれば、接合部の耐疲労性が高く、長期間の使用が可能になる。従って、特に常設されるスチールコードコンベヤベルトやパイプコンベヤベルトに好適である。
【図面の簡単な説明】
【図１】（ａ）は本発明のコンベヤベルトを示す部分破断斜視図で、（ｂ）は（ａ）のコンベヤベルトの接合部周辺を示す平面図である。
【図２】（ａ）及び（ｂ）は図１のコンベヤベルトとは異なる形態の線状心材の組合構造を有するコンベヤベルトの接合部周辺を示す平面図である。
【図３】スチールコードコンベヤベルトの一般的なベルト材を示す斜視図である。
【符号の説明】
１ コンベヤベルト
２ ベルト材
３ 接合部
４ ゴム層
５ 線状心材
６ 接着ゴム層
７ カバーゴム層
８ 端縁
９ 接着ゴム層
１０ カバーゴム層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a conveyor belt and a method for joining the conveyor belt, and more particularly to a structure of a joint portion of a conveyor belt using a steel cord or the like as a linear core and a joining method thereof.
[0002]
[Prior art]
Steel cord conveyor belts, in which steel cords are disposed as reinforcing linear core materials, are widely used for transporting mineral resources and landfill sand from the mining site to the loading port. Recently, the steel cord conveyor belt is also frequently used as a pipe conveyor belt that is used by rolling a conveyance surface into a cylindrical shape in order to prevent spillage during conveyance.
[0003]
As shown in FIG. 3, the steel cord conveyor belt includes a steel cord 12 arranged in multiple stripes in the longitudinal direction in the intermediate layer, and the periphery of the steel cord 12 in order to improve the adhesion of the steel cord 12. A belt-like belt material 11 having an adhesive rubber layer 13 coated on the surface and a wear-resistant cover rubber layer 14 laminated on the front and back surfaces of the adhesive rubber layer 13 is used, and the belt material 11 is made endless. It is formed by joining.
[0004]
As a method for joining a steel cord conveyor belt using such a belt material 11, generally,
(A) a core material exposure step of removing the cover rubber layer 14 and the adhesive rubber layer 13 at both ends of the belt material 11 by various means to expose the steel cord 12 having a length corresponding to the joint;
(B) a pair of ends of the belt material 11 from which the steel cord 12 is exposed are attached, and a core material combining step of alternately combining the steel cords 12 in a predetermined manner;
(C) an adhesive rubber layer forming step of coating the unvulcanized rubber composition for the adhesive rubber layer around the combined steel cord 12 and forming the adhesive rubber layer 13;
(D) a cover rubber layer forming step of laminating the unvulcanized rubber composition for the cover rubber layer on the front and back surfaces of the adhesive rubber layer 13 to form the cover rubber layer 14;
(E) A method including a vulcanization step of vulcanizing and integrating the unvulcanized rubber composition of the adhesive rubber layer 13 and the cover rubber layer 14 is employed.
[0005]
[Problems to be solved by the invention]
The steel cord conveyor belt is used in various parts of the world with different climates, and is particularly applied to permanent long-distance lines and has been used for many years. On the other hand, the steel cord conveyor belt has a joint as described above, and such a joint is weaker than other parts, and the fatigue resistance of the joint is reduced. Will cause trouble and shorten the service life. Although the fatigue resistance can be improved by designing the joint part long, it is difficult to make it the same as the part other than the joint part, and the workability of the joint is lowered. Therefore, when the steel cord conveyor belt is used for a long period of time, improvement of the fatigue resistance of the joint becomes a major issue.
[0006]
The present invention has been made in view of these disadvantages, and an object of the present invention is to provide a conveyor belt that has high fatigue resistance at the joint and can be used for a long period of time, and a method for joining the conveyor belt.
[0007]
[Means for Solving the Problems]
An invention relating to a conveyor belt made to solve the above problems comprises a flat belt-like rubber layer and a linear core material arranged in a plurality of strips in the longitudinal direction in the rubber layer, and is endless in at least one place. A conveyor belt having a joined portion joined in a shape, wherein short fibers are dispersedly contained in a rubber layer of the joined portion.
[0008]
According to the conveyor belt, due to the short fibers dispersed and contained in the rubber layer of the joined portion, the fatigue resistance of the joined portion is remarkably improved, and the fatigue resistance equal to or higher than that of the portion other than the joined portion is exhibited. be able to. For this reason, the life of the conveyor belt is extended, and it can be used for a long time in a long-length conveyor, a pipe conveyor, or the like.
[0009]
In the case of a conveyor belt having an adhesive rubber layer in which the rubber layer is laminated around the linear core and a cover rubber layer laminated on the front side and the back side, the dispersion-containing portion of the short fiber at the joint is bonded to the rubber. A layer and / or a cover rubber layer may be used. Thus, instead of having a linear core directly in a single rubber layer, a conveyor belt that has an adhesive rubber layer interposed between the linear core and the cover rubber layer in order to improve the adhesion of the linear core. In this case, the above-described action can be achieved by dispersing short fibers in one or both of the adhesive rubber layer and the cover rubber layer. However, the dispersion of short fibers in the adhesive rubber layer disposed around the linear core material has a greater effect of improving the fatigue resistance.
[0010]
In the conveyor belt, the short fiber may be one or more selected from the group consisting of polyester fiber, nylon fiber, aramid fiber and cellulose fiber. In particular, these short fibers have a relatively large effect of reducing the elastic modulus and the coefficient of friction, and can effectively exhibit the above-described fatigue resistance improving effect. These short fibers are preferably preliminarily dipped in a resorcin-formalin-latex solution (RFL solution) and coated to improve adhesion to rubber.
[0011]
As content of the said short fiber, 1 part or more and 30 parts or less are preferable with respect to 100 parts of rubber components of each layer (rubber layer, adhesive rubber layer, or cover rubber layer). Here, the numerical value indicated by “part” means a ratio based on mass. By setting the content of the short fibers in the above range, the above-described fatigue resistance improving effect can be effectively exhibited without inhibiting the function as a conveyor belt, for example, flexibility.
[0012]
The invention relating to the method for joining conveyor belts made to solve the above problems is as follows: (a) a linear core material arranged in multiple strips in the longitudinal direction and an adhesive covering the periphery of the linear core material; A core material that uses a belt-like belt material provided with a rubber layer and a cover rubber layer laminated on the front surface side and the back surface side, and removes the adhesive rubber layer and the cover rubber layer at both ends of the belt material to expose the linear core material. An exposure step, (b) a core material combining step in which a pair of end portions of the belt material are attached and the exposed linear core materials are alternately combined, and (c) an adhesive rubber layer around the combined linear core materials. An adhesive rubber layer forming step of filling an unvulcanized rubber composition and forming an adhesive rubber layer at a joint; and (d) laminating an unvulcanized rubber composition for a cover rubber layer on the front and back surfaces of the adhesive rubber layer. Cover to form a cover rubber layer at the joint A method for joining a conveyor belt, comprising: a rubber layer forming step; and (e) a vulcanizing step of vulcanizing the unvulcanized rubber composition for the adhesive rubber layer and the unvulcanized rubber composition for the cover rubber layer, The unvulcanized rubber composition for the adhesive rubber layer and / or the unvulcanized rubber composition for the cover rubber layer contain short fibers in a dispersed manner.
[0013]
According to the joining method of the conveyor belt, the unvulcanized rubber composition for the adhesive rubber layer and / or the unvulcanized rubber composition for the cover rubber layer used in the adhesive rubber layer forming step and the cover rubber layer forming step is short. Since the fiber is dispersedly contained, the conveyor belt of the present invention, that is, a conveyor belt having high fatigue resistance and capable of long-term use can be produced.
[0014]
In the above short fiber blending step, as the short fiber to be used, one or two or more types selected from the group consisting of polyester fiber, nylon fiber, aramid fiber and cellulose fiber may be used for the same reason as above. The content of the short fibers is preferably 1 part or more and 30 parts or less with respect to 100 parts of the rubber component in the unvulcanized rubber composition.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1A is a partially broken perspective view showing the conveyor belt of the present invention, FIG. 1B is a plan view showing the periphery of the joint portion of the conveyor belt of FIG. 1A, and FIGS. FIG. 2B is a plan view showing the vicinity of a joint portion of a conveyor belt having a combination structure of linear cores having a form different from that of the conveyor belt of FIG. 1.
[0016]
The conveyor belt 1 of FIG. 1 is formed by using a belt-like belt material 2 and joining a pair of end portions of the belt material 2 in an endless manner as in the prior art. Therefore, the conveyor belt 1 has a joint 3 at least at one place.
[0017]
The belt material 2 has the same structure as that of the conventional belt material 19 (see FIG. 3B). Specifically, a plurality of linear core materials 5 are provided in an intermediate layer in the flat rubber layer 4. It is what has. The linear core material 5 is oriented in parallel with the longitudinal direction, and is arranged in multiple lines at substantially equal intervals. The rubber layer 4 includes an adhesive rubber layer 6 that covers the periphery of the linear core material 5 and a pair of cover rubber layers 7 that are laminated on the front and back surfaces of the adhesive rubber layer 6.
[0018]
The linear core material 5 is used to ensure mechanical strength such as tensile strength in the longitudinal direction of the conveyor belt 1. As a specific material of the linear core material 5, a metal or fiber woven cord, rope, cable, or the like is used, and a steel cord having a high tensile strength is generally used.
[0019]
The cover rubber layer 7 is formed from a rubber material having wear resistance, flexibility, and the like necessary for the conveyor belt 1. As a specific rubber composition constituting the cover rubber layer 7, natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), or a mixture thereof is used as a base rubber. A vulcanizing agent, a vulcanization accelerator, a reinforcing agent such as carbon black, a filler such as calcium carbonate, a plasticizer, an anti-aging agent, a processing aid, and the like, which are usually mixed, are appropriately used.
[0020]
The adhesive rubber layer 6 is covered around the linear core material 5 in order to improve the adhesion between the linear core material 5 and the cover rubber layer 7. Specific rubber compositions for constituting the adhesive rubber layer 6 are the same as those of the rubber composition constituting the cover rubber layer 7, and organic acid cobalt, HRH (formaldehyde generator / Formaldehyde receptor / silica) type adhesion promoter, lead oxide (PbO, Pb ₂ O ₃ ) and the like are blended.
[0021]
In the joint portion 3, the linear core members 5 extending from both end edges 8 of the belt member 2 to be joined are alternately combined so as to overlap each other when viewed from the belt width direction (one-stage overlap joint method). Similarly to the belt material 2, an adhesive rubber layer 9 is covered around the combined linear core material 5, and a pair of cover rubber layers 10 are laminated on the front and back surfaces of the adhesive rubber layer 9.
[0022]
In addition, as a method of combining the linear core materials 5 in the joint portion 3, a pair of opposing linear core materials 5 overlapped as seen from the width direction, as shown in FIG. A two-stage overlap joint method that alternately repeats the case of being combined with the state and the case of being attached to each other, or a pair of opposing linear core members 5 as shown in FIG. There is a three-stage overlap joint system in which two pairs of linear cores 5 between them are combined at different positions and the tips of each other are attached at different positions.
[0023]
The rubber composition constituting the adhesive rubber layer 9 and the cover rubber layer 10 of the joint 3 is the same as the rubber composition constituting the adhesive rubber layer 6 and the cover rubber layer 7 of the belt material 2, but the conveyor The belt 1 is characterized in that short fibers are dispersed and contained in the adhesive rubber layer 9 and / or the cover rubber layer 10 of the joint portion 3 by blending short fibers with the rubber composition. Thus, by the short fibers dispersed and contained in the rubber layer 4 of the joint portion 3, that is, the adhesive rubber layer 9 and / or the cover rubber layer 10, the fatigue resistance of the joint portion 3 of the conveyor belt 1 is significantly improved. As a result, the life of the conveyor belt 1 is extended, and the conveyor can be used for a long time. In view of the effect of improving the fatigue resistance, it is preferable to disperse short fibers in both the adhesive rubber layer 9 and the cover rubber layer 10, that is, the entire rubber layer 4, but one of the adhesive rubber layer 9 and the cover rubber layer 10. The effect of improving fatigue resistance can also be obtained by adding short fibers to the dispersion. In addition, when the short fiber is dispersed and contained in one of the adhesive rubber layer 9 and the cover rubber layer 10, the adhesive rubber layer disposed around the linear core material 5 rather than the cover rubber layer 10 containing the short fiber in a dispersed manner. The effect of improving the fatigue resistance is greater when the short fibers are dispersed in 9. This is because the fatigue failure usually occurs from the periphery of the linear core material 5, so that the overall fatigue resistance can be improved by increasing the fatigue resistance of the adhesive rubber layer 9 around the linear core material 5. .
[0024]
The material of the short fiber is not particularly limited and can be appropriately selected from synthetic fiber, natural fiber, and chemical fiber. Among them, the elastic modulus and friction coefficient of the adhesive rubber layer 9 and the cover rubber layer 10 Polyester fiber, nylon fiber, aramid fiber, and cellulose fiber are preferable, and the fatigue resistance of the conveyor belt 1 can be increased by using one or more selected from the group consisting of these fibers. Can be improved effectively. The short fibers are preferably subjected to an RFL liquid coating treatment or the like as an adhesion treatment.
[0025]
In the layer containing the short fibers in a dispersed manner, the content of the short fibers in the rubber composition constituting the layer is preferably 1 part or more and 30 parts or less with respect to 100 parts of the rubber component, and 5 parts or more and 20 parts. The following are particularly preferred: This is because if the content of short fibers is smaller than the above range, the above-mentioned fatigue resistance improvement effect cannot be effectively achieved. Conversely, if the content of short fibers exceeds the above range, unvulcanized This is because moldability is deteriorated due to a decrease in fluidity of the rubber composition, and the flexibility of the conveyor belt 1 is hindered.
[0026]
Next, a method for joining the conveyor belt 1 will be described. As described above, the conveyor belt 1 includes a plurality of linear core members 5 arranged in a stripe shape in the longitudinal direction on the intermediate layer, an adhesive rubber layer 6 laminated so as to cover the linear core members 5, and this It is formed by using a belt-like belt material 2 composed of a cover rubber layer 7 laminated on the front and back surfaces of the adhesive rubber layer 6 and joining a pair of end portions of the belt material 2 endlessly.
[0027]
A method of joining the belt material 2 is as follows.
(A) a core material exposing step of removing the rubber layers 4 at both ends of the belt material 2 and exposing the linear core material 5 from the both end edges 8 to a length necessary for joining;
(B) a pair of end edges 8 of the belt material 2 and a core material combination step of combining the exposed linear core materials 5 with the one-stage overlap joint method;
(C) a short fiber blending step of blending the short fibers with the unvulcanized rubber composition for the adhesive rubber layer 9 and / or the unvulcanized rubber composition for the cover rubber layer 10 that forms the joint portion 3;
(D) The unvulcanized rubber composition for the adhesive rubber layer 9 is filled in layers around the combined linear core material 5, and the unvulcanized rubber composition for the cover rubber layer 10 is further formed on the front and back surfaces of the adhesive rubber layer 9. A rubber layer forming step of forming a rubber layer between both end edges 8 by laminating
(E) a vulcanization step of vulcanizing the unvulcanized rubber composition for the adhesive rubber layer 9 and the unvulcanized rubber composition for the cover rubber layer 10 constituting the rubber layer 4 of the joint portion 3 with a portable vulcanizer or the like; Have
[0028]
The above core material exposure process will be described in detail. First, the linear core material 5 at the end of the belt material 2 is cut out one by one by using a cutter knife or the like, and an adhesive rubber layer is formed around the linear core material 5. The cover rubber layer 7 and the adhesive rubber layer 6 are removed so as to leave 6 thin. Next, the adhesive rubber layer 6 remaining around the linear core material 5 is buffed with sandpaper, a wire brush or the like, and the surface of the linear core material 5 is cleaned using a solvent or the like. Finally, after the solvent is dried, an adhesive cement (a rubber composition for the adhesive rubber layer 9 dissolved in a solvent) is applied to the exposed surface of the linear core material 5 and the end face of the belt material 2 to adhere to the adhesive rubber layer 9. Increase sex.
[0029]
In addition, the conveyor belt of this invention and the joining method of this conveyor belt are not limited to the said embodiment, For example, although the rubber layer 4 is made into the two-layer structure of the adhesive rubber layer 6 and the cover rubber layer 7, A single rubber layer is also possible.
[0030]
【Example】
EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, of course, this invention should not be interpreted limitedly based on description of this Example.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
[Example 1]
A steel cord having a diameter of 6.3 mm is used for the linear core material, and an unvulcanized rubber composition for an adhesive rubber layer described in Formula 1 in Table 1 and an unvulcanized rubber for a cover rubber layer described in Formula 3 in Table 2. Using the composition, a tensile test specimen of Example 1 was prepared according to FIG. 6 described in JIS K6369 “Steel Cord Conveyor Belt”.
[0034]
[Example 2]
A tensile test specimen of Example 2 was prepared in the same manner as in Example 1 except that the unvulcanized rubber composition for the cover rubber layer was used as described in Formulation 4 of Table 2.
[0035]
[Example 3]
A tensile test specimen of Example 3 was prepared in the same manner as in Example 1 except that the unvulcanized rubber composition for the adhesive rubber layer was used as described in Formulation 2 of Table 1.
[0036]
[Comparative example]
The above implementation except that the unvulcanized rubber composition for the adhesive rubber layer described in Formulation 2 in Table 1 was used, and the unvulcanized rubber composition for the cover rubber layer used in Formulation 4 of Table 2 was used. In the same manner as in Example 1, a test piece for a tensile test of a comparative example was produced.
[0037]
[Characteristic evaluation]
A dynamic fatigue fracture test was performed using the tensile test specimens of Examples 1 to 3 and the comparative example, and fatigue resistance was evaluated. This fatigue resistance is evaluated by performing a dynamic fatigue fracture test in which a tensile stress is repeatedly applied to a test piece using a servo pulser and the number of times until the fracture occurs. The results are shown in Table 3 below. The number in the evaluation column for fatigue resistance in Table 3 is a ratio based on the number of fractures of the comparative example as a reference (1).
[0038]
[Table 3]

[0039]
As shown in Table 3 above, the tensile test of Example 1 in which nylon short fibers are dispersedly contained in the adhesive rubber layer and the cover rubber layer as compared with the test specimen for the tensile test similar to the conventional conveyor belt. The test specimens showed extremely high fatigue resistance, and the tensile test specimens of Examples 2 and 3 in which nylon short fibers were dispersed and contained in one of the adhesive rubber layer and the cover rubber layer also had improved fatigue resistance. Yes. Further, when the tensile test specimens of Example 2 and Example 3 are compared, the tensile test specimen of Example 2 in which nylon short fibers are dispersed and contained in the adhesive rubber layer is shorter than the nylon short fibers in the cover rubber layer. The fatigue resistance was higher than that of the specimen for tensile test of Example 3 in which was dispersed and contained.
[0040]
【The invention's effect】
As described above, according to the conveyor belt and the method of joining the conveyor belt of the present invention, the joint has high fatigue resistance and can be used for a long time. Therefore, it is particularly suitable for a steel cord conveyor belt and a pipe conveyor belt that are permanently installed.
[Brief description of the drawings]
1A is a partially cutaway perspective view showing a conveyor belt of the present invention, and FIG. 1B is a plan view showing the periphery of a joint portion of the conveyor belt of FIG.
2 (a) and 2 (b) are plan views showing the vicinity of a joint portion of a conveyor belt having a combination structure of linear core materials in a form different from that of the conveyor belt of FIG.
FIG. 3 is a perspective view showing a general belt material of a steel cord conveyor belt.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Conveyor belt 2 Belt material 3 Joining part 4 Rubber layer 5 Linear core material 6 Adhesive rubber layer 7 Cover rubber layer 8 Edge 9 Adhesive rubber layer 10 Cover rubber layer

Claims (7)

A conveyor belt comprising a flat belt-like rubber layer and a linear core material arranged in a plurality of strips in the longitudinal direction in the rubber layer, and having a joined portion joined endlessly at at least one place, It contains short fibers dispersed in the rubber layer of the joint ,
The rubber layer has an adhesive rubber layer coated around the linear core material and a cover rubber layer laminated on the front surface side and the back surface side,
A conveyor belt characterized in that the dispersion-containing portion of short fibers in the joint is an adhesive rubber layer . The conveyor belt according to claim 1, wherein short fibers are dispersed and contained only in the joint portion .   The conveyor belt according to claim 1 or 2, wherein one or two or more types selected from the group consisting of polyester fibers, nylon fibers, aramid fibers, and cellulose fibers are used as the short fibers.   The conveyor belt according to claim 1, 2 or 3, wherein the content of the short fibers is 1 part or more and 30 parts or less with respect to 100 parts of the rubber component. A belt-shaped belt member comprising a linear core material arranged in multiple strips in the longitudinal direction, an adhesive rubber layer coated around the linear core material, and a cover rubber layer laminated on the front and back sides. Using a core material exposure step of exposing the linear core material by removing the adhesive rubber layer and the cover rubber layer at both ends of the belt material;
A core material combination step of combining a pair of end portions of the belt material and alternately combining the exposed linear core materials;
An adhesive rubber layer forming step of filling an unvulcanized rubber composition for an adhesive rubber layer around the combined linear core material and forming an adhesive rubber layer of a joint portion;
A cover rubber layer forming step of laminating an unvulcanized rubber composition for a cover rubber layer on the front surface and the back surface of the adhesive rubber layer, and forming a cover rubber layer of a joint;
A vulcanization step of vulcanizing the unvulcanized rubber composition for the adhesive rubber layer and the unvulcanized rubber composition for the cover rubber layer,
A method for joining conveyor belts, comprising dispersing short fibers in the unvulcanized rubber composition for an adhesive rubber layer.   The method for joining conveyor belts according to claim 5, wherein one or two or more types selected from the group consisting of polyester fiber, nylon fiber, aramid fiber and cellulose fiber are used as the short fibers.   The conveyor belt joining method according to claim 5 or 6, wherein the content of the short fibers is 1 part or more and 30 parts or less with respect to 100 parts of the rubber component in the unvulcanized rubber composition.

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