AU2018284627B2

AU2018284627B2 - Fiber-reinforced layer for conveyer belts and conveyer belt

Info

Publication number: AU2018284627B2
Application number: AU2018284627A
Authority: AU
Inventors: Nana Tashiro
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2017-06-12
Filing date: 2018-03-22
Publication date: 2021-04-08
Anticipated expiration: 2038-03-22
Also published as: CN110546084B; AU2018284627A1; CN110546084A; JP7059523B2; JP2019001553A; WO2018230072A1

Abstract

Provided are a fiber-reinforced layer and a conveyor belt which achieve improvement in adherence between a rubber and the fiber-reinforced layer when the rubber and the fiber-reinforced layer is to be separated along the width direction of the belt. A fiber-reinforced layer 3 having a woven structure in which warp yarns 4 extend in the longitudinal direction of the belt and weft yarns 5 extend in the width direction of the belt is embedded in a conveyor belt 1 as a core body 2, and the ratio A1/A2 of an exposed area A1 of the warp yarns 4 to an exposed area A2 of the weft yarns 5 is set to 3.0-5.0, in a plan view of the fiber-reinforced layer 3. In endless processing, a cover rubber 6 is separated, at the end sections 1a in the longitudinal direction of the belt, toward the width direction of the belt, a rubber component R is left as appropriate on a surface of the fiber-reinforced layer 3, and the left rubber component R is vulcanized by including therein a vulcanization adhesive 7 or the like, whereby the end sections 1a in the longitudinal direction of the belt are bonded together.

Description

FIBER REINFORCED LAYER FOR CONVEYOR BELT AND CONVEYOR BELT

Technical Field

[0001] The present invention relates to a fiber reinforced layer for a conveyor belt and a conveyor belt and particularly relates to a fiber reinforced layer for a conveyor belt and a conveyor belt that can provide improved fixation between rubber and the fiber reinforced layer when the rubber and the fiber reinforced layer are peeled off each other in the width direction of the conveyor belt.

Background Art

[0002] To form a band-like conveyor belt into an annular shape, so-called endless machining is performed. In the endless machining, a cover rubber at each of longitudinal end portions of the belt to be joined together is removed. In a conveyor belt in which fiber reinforced layers are used as a core, a slight amount of a rubber component (adhesive rubber or the like used to bond the cover rubber and the fiber reinforced layer together) remains on the surface of each of the fiber reinforced layers during the endless machining, and vulcanization is performed with a vulcanization adhesive or the like interposed between remaining pieces of the rubber component to join the belt longitudinal end portions together (see Patent Document 1, for example).

[0003] In order to remove the cover rubber laminated on and joined to the fiber reinforced layer, a cut is formed in the cover rubber, and the cover rubber is peeled from the fiber reinforced layer such that the peeling starts at the position of the cut. In an endless machining step, no problem is posed by peeling off the cover rubber in the longitudinal direction of the conveyor belt (hereinafter referred to as the belt longitudinal direction). However, in a case where the cover rubber is peeled off in the width direction of the conveyor belt (hereinafter referred to as the belt width direction), for example, in a configuration in which the conveyor belt is over-vulcanized, an excessively small amount of the rubber component or no rubber component may remain on the surface of the fiber reinforced layer from which the cover rubber has been peeled off. An excessively small amount of the remaining rubber component prevents the belt longitudinal end portions from being firmly joined together, and the lack of the remaining rubber component precludes junction of the belt longitudinal end portions.

[0004] The inventors of the present application pursued the cause of preventing the rubber component from remaining on the surface of the fiber reinforced layer in a case where the cover rubber is peeled off in the belt width direction. The inventors of the present application studied various means for eliminating the cause and thus created the invention of the present application.

Citation List Patent Literature

[0005] Patent Document 1: JP 2014-37280 A

[0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

[0006A] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

SUMMARY

[0007] An embodiment of the present disclosure provides a method for joining a conveyor belt, a fiber reinforced layer for the conveyor belt having a woven structure in which warp threads extend in a belt longitudinal direction and weft threads extend in a belt width direction is embedded as a core. In a plan view of the fiber reinforced layer, a ratio A1/A2 between an exposed area Al of the warp threads and an exposed area A2 of the weft threads is set to not less than 3.0 and not more than 5.0. In one longitudinal end portion and the other longitudinal end portion of the conveyor belt, a cover rubber is removed by peeling off the cover rubber from the fiber reinforced layer in a belt width direction whereby a rubber component remains on a surface of the fiber reinforced layer of the one end portion and the other end portion after the cover rubber has been peeled off. Each of the fiber reinforced layers is layered and vulcanized with a vulcanization adhesive interposed between the remaining rubber components. The one end portion and the other end portion are joined by joining the opposed surfaces of the fiber reinforced layer.

[0008] In a conveyor belt according to an embodiment of the present disclosure, the fiber reinforced layer for the conveyor belt described above is embedded at least as an uppermost layer and a lowermost layer of a core.

[0009] According to an embodiment of the present disclosure, in a plan view of the fiber reinforced layer, the ratio A1/A2 between the exposed area Al of the warp threads and the exposed area A2 of the weft threads is lower than a conventional ratio and is set to not less than 3.0 and not more than 5.0. Since the ratio A1/A2 is set to a value lower than the conventional ratio, in a case where the rubber and the fiber reinforced layer are peeled off each other in the belt width direction, filaments forming the warp threads are unlikely to be pulled open by the rubber. Accordingly, breakage of filament portions of the warp threads is suppressed, and an adhesive layer adhering to the surface of the fiber reinforced layer is less likely to be separated from the warp threads. Thus, according to an embodiment of the present disclosure, it is possible to improve fixation between the rubber and the fiber reinforced layer.

[0010] In a case where the rubber is peeled off in the belt longitudinal direction, the ratio A1/A2 set to not less than 3.0 prevents filaments forming the weft threads from being pulled excessively open by the rubber. Accordingly, regardless of the direction in which the rubber is peeled off, an appropriate amount of the rubber component can be left on the surface of the fiber reinforced layer. Thus, by vulcanizing the conveyor belt with a vulcanization adhesive or the like interposed between pieces of the rubber component remaining at the respective belt longitudinal end portions, the belt longitudinal end portions can be firmly joined together.

Brief Description of Drawings

[0011] FIG. 1 is a cross-sectional view illustrating a conveyor belt in which a fiber reinforced layer for the conveyor belt is embedded according to an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating the conveyor belt of FIG. 1 in a plan view. FIG. 3 is an explanatory diagram illustrating the conveyor belt of FIG. 1 mounted between pulleys. FIG. 4 is a cross-sectional view taken along line X-X in FIG. 3. FIG. 5 is an explanatory diagram illustrating the fiber reinforced layer of FIG. 1 in an enlarged plan view. FIG. 6 is an explanatory diagram illustrating a step of peeling a cover rubber of FIG. 1 in a cross-sectional view. FIG. 7 is an explanatory diagram illustrating, in a side cross-sectional view, a step of joining fiber reinforced layers with a rubber component remaining on surfaces of the layers.

WO 2018/230072 Al PCT/JP2018/011347

FIG. 8 is an explanatory diagram illustrating the fiber reinforced layers of FIG. 7 joined together in a side cross-sectional view. FIG. 9 is an explanatory diagram schematically illustrating, in an enlarged plan view, a fiber reinforced layer during a step of peeling a cover rubber. FIG. 10 is an explanatory diagram illustrating another embodiment of a fiber reinforced layer in an enlarged plan view.

Description of Embodiments

[0012] A fiber reinforced layer for a conveyor belt and a conveyor belt according to embodiments of the present invention will be described below based on the embodiments illustrated in the drawings.

[0013] In a conveyor belt 1 of an embodiment of the present invention illustrated in FIGS. 1 and 2, fiber reinforced layers 3 for a conveyor belt (hereinafter referred to as the fiber reinforced layers 3) of the embodiment of the present invention are embedded as a core 2. The core 2 is a member bearing tension occurring in the conveyor belt 1 that is mounted. Adhesive rubber is attached to a surface of each of the fiber reinforced layers 3, and a cover rubber 6 is disposed above and below the core 2, respectively. The core 2 and the cover rubber 6 are integrated by vulcanization bonding. The core 2 is continuous in the belt longitudinal direction, and a width direction dimension is slightly smaller than a belt width. Accordingly, both ends of the conveyor belt 1 in the width direction include an edge rubber without the core 2. Note that an arrow L in the drawing indicates the belt longitudinal direction (the longitudinal direction of the conveyor belt 1), and an arrow W indicates the belt width direction (the width direction of the conveyor belt 1).

[0014] As illustrated in FIGS. 3 and 4, the conveyor belt 1, formed into an annular shape by joining longitudinal ends of the belt 1 together, is mounted between pulleys 8a, 8b for use. On a conveying side where conveyed objects 10 are carried, both end portions of the belt in the width direction are supported, at a lower surface of the belt, by support rollers 9 with a rotating shaft inclined at a predetermined angle a with respect to the horizontal direction, and a central portion of the belt in the width direction is supported, at the lower surface of the belt, by the support roller 9 with a horizontal rotating shaft. Accordingly, both end portions of the belt in the belt width direction are bent upward with respect

WO 2018/230072 Al PCT/JP2018/011347

to the central portion in the belt width direction, and the conveyor belt 1 is used in a trough shape. When the conveyor belt 1 is bent around the pulleys 8a, 8b, the highest tensile stress is generated in the fiber reinforced layer 3 disposed at the outermost circumference of the annular conveyor belt 1, and the highest compressive stress is generated in the fiber reinforced layer 3 disposed at the innermost circumference.

[0015] In the present embodiment, the core 2 has a four-layer structure including four fiber reinforced layers 3 of the embodiment of the present invention. The core 2 is not limited to the four-layer structure and may have a single layer structure or any other multilayer structure.

[0016] As illustrated in FIG. 5, the fiber reinforced layer 3 has a plain weave structure in which warp threads 4 extend in the belt longitudinal direction and in which weft threads 5 extend in the belt width direction, the warp threads 4 and the weft threads 5 being alternately interlaced with one another in the vertical direction. The fiber reinforced layer 3 is embedded such that the extension direction of the warp threads 4 corresponds to the belt longitudinal direction.

[0017] As the warp threads 4, multifilament yarns are used that are formed by twisting a plurality of filaments. As the weft threads 5, monofilament yarns are used that are formed by twisting a multifilament yarn or a single filament. The warp threads 4 and the weft threads 5 can be made of the same material or different materials. As the warp threads 4, for example, polyester fibers are used, and as the weft threads 5, for example, polyamide fibers are used. Examples of polyamide fibers include nylon 6 and nylon 66.

[0018] In the embodiment of the present invention, in a plan view of the fiber reinforced layer 3, a ratio A1/A2 between an exposed area Al of the warp threads 4 and an exposed area A2 of the weft threads 5 is set to not less than 3.0 and not more than 5.0. The exposed area Al of the warp threads 4 is the area of the fiber reinforced layer 3 excluding portions that are covered with the weft threads 5 and are thus not visible, in a plan view. The exposed area A2 of the weft threads 5 is the area of the fiber reinforced layer 3 excluding portions that are covered with the warp threads and are thus not visible, in a plan view. In FIG. 5, the region of the exposed area Al is indicated by dot-dash oblique lines, and the region of the exposed area A2 is indicated by dashed oblique lines.

WO 2018/230072 Al PCT/JP2018/011347

[0019] It is important that the fiber reinforced layer has a sufficient strength in the belt longitudinal direction. Thus, the warp threads are commonly thicker than the weft threads, and in the related art, the ratio A1/A2 is, for example, not less than 5.3. On the other hand, the fiber reinforced layer 3 of the embodiment of the present invention has a smaller ratio A1/A2 than known fiber reinforced layers. In other words, the exposed area Al of the warp threads 4 is smaller in the fiber reinforced layer of the embodiment of the present invention than in the known fiber reinforced layers.

[0020] In a case where the conveyor belt 1 is formed into an annular shape, longitudinal ends la of the conveyor belt 1 shaped like a band are joined together by endless machining. In the endless machining, a cut is formed in the cover rubber 6, and the cover rubber is peeled off from the fiber reinforced layers 3 such that the peeling starts at the position of the cut. The cover rubber 6 is peeled off in the belt width direction as illustrated in FIG. 6.

[0021] In a case where the core 2 includes a plurality of the fiber reinforced layers 3, the cover rubber 6 is removed at each of the longitudinal ends la as illustrated in FIG. 7, to form the stepped fiber reinforced layers 3. One of the plurality of fiber reinforced layers 3 is peeled off in the belt width direction. In this peeling operation, the fiber reinforced layer 3 and the adhesive rubber between the fiber reinforced layers 3 are peeled off in the belt width direction. After the peeling operation, a slight amount of a rubber component R (adhesive rubber or the like) remains on the surface of each fiber reinforced layer 3.

[0022] Then, as illustrated in FIG. 8, a vulcanization adhesive 7 is applied to surfaces of pieces of the rubber component R remaining at the respective belt longitudinal end portions la. Then, vulcanization is performed with the vulcanization adhesive 7 or the like interposed between the pieces of the rubber component R to join the opposed surfaces of the plurality of layered fiber reinforced layers 3. Accordingly, the belt longitudinal ends la are joined together to form an annular conveyor belt 1.

[0023] During the peeling operation described above, a peeling force f acts on the warp threads 4 as illustrated in FIG. 9. Thus, gaps between filaments 4a forming the warp threads 4 are enlarged due to the peeling force f opening the filaments 4a. Note that the extension direction of the weft threads 5 is substantially orthogonal to the extension direction of the warp threads 4. Thus, even in a case where the peeling force f acts on the weft threads 5, filaments 5a forming the weft threads 5 are prevented from being opened like the filaments 4a forming the warp threads 4.

[0024] The inventors of the present application have found that, in a case where the filaments 4a are open, the filament 4a portions become easy to break, causing the adhesive layer adhering to the filaments 4a to adhere integrally to the peeled-off cover rubber 6 side, and that the adhesion partly contributes to hindering the rubber component R from remaining on the surface of the fiber reinforced layer 3. Thus, based on this finding, the ratio A1/A2 described above in the fiber reinforced layer 3 of the embodiment of the present invention is smaller than the ratio A1/A2 in the related art and is set to not more than 5.0.

[0025] Reducing the ratio A1/A2 decreases the area of the warp threads 4 on which the peeling force f acts directly. Thus, even with the action of the same peeling force f, the filaments 4a of the warp threads 4 are less likely to open, thus making the rubber component R more likely to remain on the surface of the fiber reinforced layer 3. As a result, even in a case where the rubber is peeled off in the belt width direction, the plurality of fiber reinforced layers 3 can be firmly joined together, and thus the longitudinal ends la can be firmly joined together.

[0026] When the ratio A1/A2 is less than 3.0, in a case where the rubber is peeled off in the belt longitudinal direction, the filaments 5a of the weft threads 5 are likely to be opened due to the peeling force exerted at that time in a case where the weft threads 5 are multi-filament yarns. As a result, the rubber component R is less likely to remain on the surface of the fiber reinforced layer 3. Thus, in the embodiment of the present invention, the ratio A1/A2 is set to not less than 3.0 and not more than 5.0.

[0027] The embodiment of the present invention provides a beneficial solution for a new problem posed in a case where rubber such as the cover rubber 6 is peeled off in the belt width direction, that is, a problem that has not been addressed for endless machining. Moreover, even in a case where the rubber is peeled off in the belt longitudinal direction or obliquely with respect to the belt longitudinal direction, a sufficient amount of the rubber component R remains

WO 2018/230072 Al PCT/JP2018/011347

on the surface of the fiber reinforced layer 3 after the peeling operation. This allows the longitudinal ends la to be firmly joined together.

[0028] Specifically, options for reducing the ratio A1/A2 include reducing the thickness of each of the warp threads 4 (reducing a fineness F1 of each warp thread 4), reducing the arrangement density of the warp threads 4, increasing the thickness of each of the weft threads 5 (increasing a fineness F2 of the weft thread 5), and increasing the arrangement density of the weft threads 5. An excessively reduced thickness of each warp thread 4 or an excessively reduced arrangement density of the warp threads 4 disadvantageously hinders the fiber reinforced layer 3 from being provided with the appropriate strength in the belt longitudinal direction. On the other hand, an excessively increased thickness of each weft thread 5 or an excessively reduced arrangement density of the warp threads 4 increases a crimp ratio of the warp threads 4 (the degree to which the warp threads 4 are bent in the vertical direction). This correspondingly increases temporal elongation of the mounted conveyor belt 1, leading to problems such as the likelihood of meandering of the conveyor belt 1. Thus, for the fineness Fl and the arrangement density of the warp threads 4, and the fineness F2 and the arrangement density of the weft threads 5, values within the appropriate ranges are set according to the usage conditions and the like of the conveyor belt 1.

[0029] Thus, a ratio F1/F2 between the fineness Fl of the warp thread 4 and the fineness F2 of the weft thread 5 is preferably set to not less than 1.5 and not more than 2.5. A ratio F1/F2 of less than 1.5 is likely to lead to an excessively high crimp ratio of the warp 4, and a ratio F1/F2 of more than 2.5 is likely to lead to an excessively large exposed area Al of the warp threads 4.

[0030] A twist coefficient Ti calculated by the following formula (1) for the weft threads 5 is preferably set to not less than 20 and not more than 50. 2 Twist coefficient TI = (T/10) x (D)/ ... (1) T in Formula (1) is the number of twists per 10 cm of the weft thread 5 and D is the fineness of the weft thread 5 (dtex).

[0031] The twist coefficient TI of less than 20 is advantageous in reducing the exposed area Al of the warp threads 4 but is disadvantageous in reducing the exposed area A2 of the weft threads 5 and also in ensuring sufficient fatigue

WO 2018/230072 Al PCT/JP2018/011347

resistance of the weft threads 5. A twist coefficient Ti of more than 50 is disadvantageous in reducing the exposed area Al of the warp threads 4.

[0032] The twist direction of the warp threads 4 and the weft threads 5 may be either an S direction (rightward twist) or a Z direction (leftward twist). However, as illustrated in FIG. 10, the warp threads 4 having opposite twist directions are preferably alternately arranged in the belt width direction such that each warp thread 4 alternates with the warp thread 4 having the opposite twist direction or such that a plurality of, for example, two warp threads 4 having the same twist direction alternate with the same number of warp threads 4 having the same twist direction that is opposite to the twist direction of the warp threads 4 described above. Since the warp threads 4 with the S twist direction and the warp threads 4 with the Z twist direction are alternately woven in the belt width direction, in a case where the cover rubber 6 is peeled off in the belt width direction, the filaments 4a of half of the warp threads 4 in the fiber reinforced layer 3 are likely to be opened, whereas the filaments 4a of the other half of the warp threads 4 are tightly twisted. Thus, regardless of whether the cover rubber 6 is peeled off from one side or the other side in the belt width direction, an appropriate amount of the rubber component R is likely to be left on the surface of the fiber reinforced layer 3. Accordingly, by configuring the fiber reinforced layer 3 such that the warp threads 4 with the S twist direction and the weft threads 4 with the Z twist direction are alternately woven in the belt width direction, the directionality of the fixation between the rubber and the fiber reinforced layer 3 can be eliminated.

[0033] Compared to polyester fibers, polyamide fibers adhere appropriately to the rubber. Thus, employing polyester fibers as the warp threads 4 and polyamide fibers as the weft threads 5 is advantageous in improving the fixation between the rubber and the fiber reinforced layer 3 when the rubber is peeled off in the belt width direction.

[0034] In a configuration in which the core 2 includes a plurality of fiber reinforced layers, the fiber reinforced layer 3 of the embodiment of the present invention may be used as all of the fiber reinforced layers. However, to keep costs low, the fiber reinforced layer 3 of the embodiment of the present invention can be used as only some of the fiber reinforced layers, while inexpensive general-purpose fiber reinforced layers can be used as the remaining fiber reinforced layers. In this case, the fiber reinforced layer 3 of the

WO 2018/230072 Al PCT/JP2018/011347

embodiment of the present invention is disposed at the outermost position; the outermost layer is most susceptible to heat caused by vulcanization when the conveyor belt 1 is produced.

[0035] In other words, the band-like conveyor belt 1 that has not been formed into an annular shape yet is configured such that the fiber reinforced layer 3 of the embodiment of the present invention is employed at least as the uppermost fiber and the lowermost layer of the fiber reinforced layer forming the core 2. Of course, the conveyor belt can be configured such that the fiber reinforced layer 3 of the embodiment of the present invention is employed only as the uppermost fiber and the lowermost layer. With such a configuration, the effect of the fiber reinforced layer 3 described above can be efficiently obtained with the used amount of the fiber reinforced layer 3 minimized.

Examples

[0036] As samples of the fiber reinforced layer, seven types of fiber reinforced layers (Conventional Example, Comparative Example, and Examples 1 to 5) were manufactured according to the specifications shown in Table 1. Additionally, samples of the conveyor belt were manufactured using each of the samples of the fiber reinforced layer. In Table 1, PET means polyester, and N66 means nylon 66. Additionally, in Table 1, Al means the exposed area of the warp threads, A2 means the exposed area of the weft threads, Fl means the fineness of the warp threads, and F2 means the fineness of the weft threads. The conveyor belt samples have the same configuration except for the configuration of the fiber reinforced layers forming the core. Two fiber reinforced layers are embedded in each of the conveyor belt samples.

[0037] The following belt length change rate and warp thread strength utilization factor were measured for each of the conveyor belt samples. Additionally, the following peel test (fixation between the fiber reinforced layer and the rubber) was performed on each of the fiber reinforced layer samples. The test results are as shown in Table 1.

WO 2018/230072 Al PCT/JP2018/011347

[0038]

[Table 1] Conventional Comparative Example Example Example Example Example

Example Example 1 2 3 4 5

Woven structure Plain weave <- - - - -

Warp PET thread Material Weft PET -<- N66 thread

Twisted

structure of Warp four 1100 thread dtex

filaments

Structure Twisted Twist Twisted structure structure structure of Weft of two of one four 1100 thread 1100 2100 dtex dtex dtex Specifications filaments filaments filament of fiber Arrangement Warp reinforced 61 61 61 61 61 61 61 density thread layer (Number of Weft threads/5 20 35 25 35 35 35 35 thread cm)

Warp Twist count 10.0 10.0 10.0 10.0 10.0 10.0 10.0 thread

(Number of Weft twists/10 9.0 9.0 9.0 13.0 7.5 7.5 7.5 thread cm)

Twist coefficient Tl 60 60 60 61 35 35 34

S/Z (one S-twist

Warp yarn twist thread alternates S direction with one Z-twist

thread)

Al/A2 5.3 2.5 4.0 4.0 4.4 3.5 3.1

Fl/F2 1.0 1.0 1.0 2.0 2.0 2.0 2.1

WO 2018/230072 Al PCT/JP2018/011347

Belt length change rate 100 200 120 130 120 100 100 (index value)

Warp thread strength utilization

factor 100 80 100 120 130 130 130

(index value)

Peel in belt

longitudinal 100 40 100 100 100 100 100 direction (index

value) Peel test

Peel in belt width

direction (index 100 400 400 400 450 450 500

value)

[0039] Belt Length Change Rate Each of the conveyor belt samples was mounted between pulleys under the same conditions, and traveling tests were performed under the same conditions. The circumferential length of the sample was measured before and after traveling, and the rate of change in circumferential length was determined. The rate of change is expressed as an index value and evaluated with Conventional Example being assigned as a reference 100. Smaller values indicate suppression of a temporal increase in circumferential length and the superiority of the fiber reinforced layer.

[0040] Warp Thread Strength Utilization Factor For each of the conveyor belt samples not having traveled yet, the strength utilization factor F for the warp threads calculated according to Formula (2) below was determined. The strength utilization factor F = (extension direction breaking strength of warp threads per unit width of fiber reinforced layer/ (tensile breaking strength of one warp thread x number of warp threads per unit width of fiber reinforced layer)) x 100% --- (2) The strength utilization factor F is an indicator indicating how much of the tensile strength inherently possessed by the warp thread in the fiber reinforced layer can be exerted, and a larger F value means effective, efficient

WO 2018/230072 Al PCT/JP2018/011347

exertion of the strength of the warp thread and the superiority of the fiber reinforced layer. In Table 1, the strength utilization factor of the Conventional Example is assigned as the reference 100, and a larger index value indicates superiority.

[0041] Peel Test Test pieces were produced using each fiber reinforced layer sample in accordance with JIS K 6256-1: 2013 "Adhesion to textile fabric". Each of the test pieces was obtained by vulcanizing each sample interposed between the adhesive rubber (NR weight ratio of 50%) and the cover rubber (NBR weight ratio of 20%, SBR weight ratio of 40%) for integration. Then, in accordance with JIS K 6256-1: 2013 "Adhesion to textile fabric", the sample and the adhesive rubber were peeled off each other, and the area of the adhesive rubber remaining on the surface of the sample, which had been joined to the adhesive rubber, was measured. The sample was peeled off in two directions: the belt longitudinal direction (extension direction of the warp threads) and the belt width direction (extension direction of the weft threads). In other words, the test conditions are common to each test piece except for the use of the different fiber reinforced layers. The area of the remaining adhesive rubber is expressed as an index value and evaluated with Conventional Example being assigned as the reference 100, and a larger index value means a larger amount of remaining adhesive rubber and the superiority of the fiber reinforced layer.

[0042] The results in Table 1 indicate that Examples 1 to 5 provide performance equivalent to that of Conventional Example in terms of the belt length temporal change rate, the fatigue resistance, and the warp thread strength utilization factor and leave a much larger amount of rubber in the fiber reinforced layer than Conventional Example in a case where the rubber and the fiber reinforced layer are peeled off each other in the belt width direction.

Reference Signs List

[0043] 1 Conveyor belt la Longitudinal end 2 Core 3 Fiber reinforced layer 4 Warp thread 4a Filament

WO 2018/230072 Al PCT/JP2018/011347

5 Weft thread 5a Filament 6 Cover rubber 7 Vulcanization adhesive 8a, 8b Pulley 9 Support roller 10 Conveyed object R Rubber component

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

[Claim 1] A method for joining a conveyor belt, a fiber reinforced layer for the conveyor belt having a woven structure in which warp threads extend in a belt longitudinal direction and weft threads extend in a belt width direction is embedded as a core, wherein in a plan view of the fiber reinforced layer, a ratio Al/A2 between an exposed area Al of the warp threads and an exposed area A2 of the weft threads being set to not less than 3.0 and not more than 5.0; in one longitudinal end portion and the other longitudinal end portion of the conveyor belt, a cover rubber is removed by peeling off the cover rubber from the fiber reinforced layer in a belt width direction whereby a rubber component remains on a surface of the fiber reinforced layer of the one end portion and the other end portion after the cover rubber has been peeled off; each of the fiber reinforced layers is layered and vulcanized with a vulcanization adhesive interposed between the remaining rubber components; and the one end portion and the other end portion are joined by joining the opposed surfaces of the fiber reinforced layer.
[Claim 2] The method for joining a conveyor belt according to claim 1, wherein a ratio F1/F2 between a fineness Fl of each of the warp threads and a fineness F2 of each of the weft threads is set to not less than 1.5 and not more than 2.5.
[Claim 3] The method for joining a conveyor belt according to claim 1 or 2, wherein a twist coefficient TI, calculated according to Formula (1), of the weft threads is set to not less than 20 and not more than 50, 2 twist coefficient TI = (T/10) x (D)1/ ... (1)

where T is the number of twists per 10 cm of the weft thread and D is the fineness (dtex) of the weft thread.
[Claim 4] The method forjoining a conveyor belt according to any one of claims I to 3, wherein the warp yarns with an S direction twist and the warp yarns with a Z direction twist are alternately arranged in the belt width direction.
[Claim 5] The method forjoining a conveyor belt according to any one of claims I to 4, wherein the warp threads comprise polyester fibers and the weft threads comprise polyamide fibers.
[Claim 6] The method for joining a conveyor belt comprising the fiber reinforced layer for a conveyor belt described in any one of claims 1 to 5 embedded in the conveyor belt as at least an uppermost layer and a lowermost layer of the core.

WO 2018/230072 A1 PCT/JP2018/011347 1/6

WO 2018/230072 A1 PCT/JP2018/011347 2/6

WO 2018/230072 A1 PCT/JP2018/011347 3/6

WO 2018/230072 A1 PCT/JP2018/011347 4/6

WO 2018/230072 A1 PCT/JP2018/011347 5/6

WO 2018/230072 A1 PCT/JP2018/011347 6/6