Conveyor belt

Abstract

Provided is a conveyor belt capable of reducing the possibility of breakage of a motor and / or a pulley in a conveying facility, without curing even in a low-temperature environment. A conveyor belt 1 is constituted by stacking a thermoplastic resin layer 11 having a durometer hardness A85 or less as specified in JIS K7311 at -30°C, and a canvas layer 12 obtained by impregnating a woven fabric 120 with polyester resin. The conveyor belt 1 can maintain flexibility even in a low-temperature environment, does not cure, and can reduce the possibility of breakage of a motor and / or a pulley in a conveying facility.

Description

Conveyor belt

[0001] The present invention relates to a conveyor belt.

[0002] Conveyor belts having a belt body in which a thermoplastic resin layer such as polyurethane resin and a canvas layer such as polyester canvas are laminated are used in various situations such as logistics and food factories. With the spread of frozen foods, such conveyor belts are sometimes used in warehouses with temperatures below -30°C.

[0003] For example, Patent Document 1 discloses a technology in which a resin layer is laminated on a canvas layer and multiple protrusions are formed on the surface of the resin layer as a conveyor belt for conveying food such as cooked rice, bread dough, etc. Also, Patent Document 2 discloses a toothed belt for power transmission and conveyance, which includes a main body made of a thermoplastic elastomer, a core wire as a tension member, and canvas covering the belt tooth surface.

[0004] JP 2021-134038 A JP 2004-347054 A

[0005] However, the techniques described in Patent Documents 1 and 2 have a problem in that when a conveyor belt is used in a low-temperature environment of −30° C. or below, the thermoplastic resin layer used in the belt body hardens, making the conveyor belt susceptible to damage such as cracks on the surface of the thermoplastic resin layer and breakage of the joints of the belt body. Even if the conveyor belt is not damaged, the reduced flexibility increases the load on the motors and pulleys of the conveying equipment on which the conveyor belt is tensioned, which may result in damage to these parts.

[0006] In addition, for example, in cold regions, if the conveyor belt is left in a low-temperature environment for a long period of time, such as when the conveyor equipment is stopped at night and restarted the next morning, the conveyor belt may become hard even if the temperature does not reach -30°C, and the conveyor belt in contact with the pulley may become imprinted with the pulley. If the conveyor belt becomes imprinted with the pulley, a load is placed on the motor when the conveyor belt is running, which may lead to deterioration or damage to the conveyor equipment.

[0007] An object of the present invention is to provide a conveyor belt that does not harden even in a low-temperature environment and that reduces the possibility of damage to motors and pulleys of conveyor equipment.

[0008] The conveyor belt of the present invention is a conductive conveyor belt and is constructed by laminating at least one thermoplastic resin layer having a durometer hardness of A85 or less as specified in JIS K7311 at −30° C. and a canvas layer.

[0009] According to the present invention, the flexibility of the conveyor belt can be maintained even in a low-temperature environment, and the belt does not harden, reducing the possibility of damage to the motors and pulleys of the conveyor equipment.

[0010] FIG. 1 is a schematic diagram showing the configuration of a conveying facility according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of a conveying belt according to a first embodiment. FIG. 3 is a cross-sectional view showing the configuration of a conveying belt according to a second embodiment. FIG. 4 is a cross-sectional view showing the configuration of a conveying belt according to a third embodiment. FIG. 5 is a cross-sectional view showing the configuration of a conveying belt according to a fourth embodiment. FIG. 6 is a cross-sectional view showing the configuration of a conveying belt according to a fifth embodiment. FIG. 7 is a cross-sectional view showing the configuration of a conveying belt according to a sixth embodiment. FIG. 8 is a cross-sectional view showing the configuration of a conveying belt according to a seventh embodiment. FIG. 9 is a cross-sectional view showing the configuration of a conveying belt according to an eighth embodiment. FIG. 10 is a cross-sectional view showing the configuration of a conveying belt according to a ninth embodiment. FIG. 11 is a cross-sectional view showing the configuration of a conveying belt according to a tenth embodiment.

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the same components are given the same reference numerals and redundant description will be omitted.

[0012] (1) First Embodiment Fig. 1 is a schematic diagram showing the configuration of a conveying equipment CM equipped with a conveying belt 1 according to this embodiment. The conveying equipment CM includes a drive pulley DP and a driven pulley TP (simply referred to as pulleys DP and TP when no distinction is made) that are spaced apart from each other. The conveying belt 1, which is an endless belt formed by connecting ends of a band-shaped belt with a joint, is wound around the drive pulley DP and the driven pulley TP. The conveying equipment CM can also be used in other embodiments, such as the second embodiment.

[0013] The drive pulley DP is driven to rotate by a power source such as a motor (not shown), moving the conveyor belt 1 toward the driven pulley TP. The front surface of the conveyor belt 1 serves as a conveying surface 1A on which an object to be conveyed (CG) is placed. The back surface 1B of the conveyor belt 1, which faces the conveying surface 1A, contacts the pulleys DP and TP. The object to be conveyed (CG) moves in the conveying direction together with the conveying surface 1A due to the rotation of the drive pulley DP.

[0014] Next, a conveyor belt 1 according to the first embodiment will be described. As shown in FIG. 2, the conveyor belt 1 is formed by laminating a thermoplastic resin layer 11 and a canvas layer 12. The surface of the thermoplastic resin layer 11 of the conveyor belt 1 forms a flat conveying surface 1A, and the exposed back surface of the canvas layer 12 forms the back surface 1B of the conveyor belt 1. The thickness of the conveyor belt 1 is preferably 0.6 mm or more and 8.0 mm or less. Considering the conveying capacity of the conveyed object CG, the thickness of the conveyor belt 1 is more preferably 0.6 mm or more and 3.5 mm or less. In the following description, the left-right direction in FIG. 2 is the conveying direction of the conveyor belt 1, and the depth direction of the paper in FIG. 2 is the width direction of the conveyor belt 1, which is perpendicular to the conveying direction. This also applies to other embodiments, such as the second embodiment.

[0015] The thermoplastic resin layer 11 is composed of a thermoplastic resin having a glass transition temperature of -30°C or lower, such as an ether-based thermoplastic polyurethane resin. Furthermore, the thermoplastic resin layer 11 preferably has a durometer hardness of A85 or lower at -30°C as defined in JIS K7311, and more preferably a durometer hardness of A75 to A79. This durometer hardness A is an index indicating the hardness of rubber, thermoplastic elastomers, etc., and is measured using a durometer type A in JIS K7311. Having a glass transition temperature of -30°C or lower allows the thermoplastic resin layer 11 to maintain its flexibility and not harden even in low-temperature environments, reducing the possibility of damage to the motor and pulleys DP and TP of the conveying equipment CM. In particular, if the thermoplastic resin layer 11 has a durometer hardness of A85 or lower at -30°C, it will not harden even in low-temperature environments of -30°C. Since the conveying belt 1 does not harden even in a low temperature environment of -30°C, even if the conveying belt 1 is stretched over the pulleys DP and TP, the possibility of damaging the motor of the conveying equipment CM or the pulleys DP and TP is further reduced, and the conveyed object CG can be conveyed stably.

[0016] Furthermore, the thermoplastic resin layer 11 preferably has a durometer hardness of A75 or more at 23°C, which corresponds to room temperature. By making the thermoplastic resin layer 11 have a durometer hardness of A75 or more at 23°C, the thermoplastic resin layer 11 itself can be imparted with tensile strength. The conveyor belt 1 is primarily imparted with tensile strength by the canvas layer 12. However, it is preferable to provide a thermoplastic resin layer 11 having a durometer hardness of A75 or more at 23°C so that the thermoplastic resin layer 11 also imparts tensile strength at room temperature. The tensile strength of the conveyor belt 1 in a low-temperature environment of -30°C is preferably less than 150% of the tensile strength in a room-temperature environment of 23°C. The tensile strength can be measured using a tensile tester equipped with a thermostatic chamber that can be adjusted to a -30°C environment. The measurement method involves grasping the top and bottom of the conveyor belt 1 in the longitudinal direction, stretching it at a specific elongation rate, and measuring the tension after leaving it to stand for 30 minutes. The elongation rate during the test is preferably the elongation rate actually used.

[0017] An example of a thermoplastic resin layer 11 that satisfies these performance requirements is Pandex T-8375 (registered trademark: manufactured by DIC Covestro Polymer Co., Ltd.), an ether-based thermoplastic polyurethane resin. Pandex T-8375 has a durometer hardness of A77 at 23°C and a durometer hardness of A85 or less at -30°C. The color of the resin constituting the thermoplastic resin layer 11 is not particularly limited, and it may be transparent or colored and opaque. When the belt ends are joined to form the endless conveyor belt 1, the thickness of the thermoplastic resin layer 11 is preferably 0.3 mm or greater to ensure that the joints at the belt ends have strength equivalent to that of a resin belt with a durometer hardness of A80 or greater.

[0018] The canvas layer 12 includes a woven fabric 120 and an impregnated resin portion 123. The thickness of the canvas layer 12 is preferably 0.3 mm or more and 1.0 mm or less. The woven fabric 120 is formed by weaving weft yarns 121 along the width direction of the conveyor belt 1 and warp yarns 122 along the conveying direction. The weft yarns 121 and warp yarns 122 may be made of, for example, PET (Poly Ethylene Terephthalate) or nylon, and are not particularly limited in material. The weft yarns 121 and warp yarns 122 may be either monofilament or multifilament. However, it is preferable that the weft yarns 121 be monofilament or multifilament and the warp yarns 122 be multifilament. By using multifilament warp yarns 122, the tensile strength of the warp yarns 122 can be improved, thereby improving the tensile strength of the conveyor belt 1 in the running direction. Furthermore, by using monofilaments for the weft yarns 121, the flexibility of the canvas layer 12 can be ensured, and the flexibility of the conveyor belt 1 is not impaired.

[0019] The impregnated resin portion 123 is used to improve the adhesion between the woven fabric 120 and the thermoplastic resin layer 11, and is formed in the gaps in the weave of the woven fabric 120. A thermoplastic urethane resin generally used for adhesive treatment can be used as the impregnated resin portion 123. Ether-based polyurethane, ester-based polyurethane, or polycarbonate-based urethane resin is preferred as the thermoplastic urethane resin for the impregnated resin portion 123. The impregnated resin portion 123 can be formed by performing a dipping process or a coating process on the woven fabric 120 to impregnate the woven fabric 120 with the thermoplastic urethane resin.

[0020] It is preferable to impart electrical conductivity to the conveyor belt 1 to provide an antistatic effect. Examples of methods for imparting electrical conductivity include a method of incorporating an electrically conductive filler into at least one of the thermoplastic resin layer 11 and the impregnated resin portion 123 of the canvas layer 12, and a method of weaving electrically conductive threads or metal wires into at least one of the weft threads 121 and the warp threads 122 that constitute the woven fabric 120 of the canvas layer 12.

[0021] The conductive filler that imparts an antistatic effect is not particularly limited as long as it can impart conductivity when blended with a resin, and examples thereof include carbon-based fillers such as carbon black, carbon nanotubes, carbon fiber, and graphite, as well as oxides of iron and copper. Carbon-based conductive fillers are particularly preferred because of their high conductivity. The surface electrical resistance of the conveyor belt 1 is 10 ９ Preferably, the electrical resistance is Ω / □ or less. As the conductive thread that provides the antistatic effect, metal threads such as iron and copper threads, carbon fiber, etc. can be used.

[0022] According to the above configuration, the conveyor belt 1 is constructed by laminating one thermoplastic resin layer 11 having a durometer hardness of A85 or less as specified in JIS K7311 at -30°C and one canvas layer 12. This allows the conveyor belt 1 to maintain flexibility even in low-temperature environments without hardening, reducing the possibility of damage to the motor and pulleys DP and TP of the conveyor equipment CM. Verification tests were conducted in which the conveyor belt 1 having the above configuration was wound around the pulleys DP and TP of the conveyor equipment CM and conveyed the object CG in a low-temperature environment of -30°C. The verification tests confirmed that the object CG could be conveyed more than 10 million times. Furthermore, by using the flexible thermoplastic resin layer 11 as the conveying surface 1A of the conveyor belt 1, the object CG can be efficiently conveyed without slipping on the conveying surface 1A, even in low-temperature environments.

[0023] (2) Second Embodiment In the first embodiment, the conveyor belt 1 is described in which one thermoplastic resin layer 11 and one canvas layer 12 are laminated. However, the present invention is not limited to this. For example, a conveyor belt may be provided in which two thermoplastic resin layers and two canvas layers are laminated alternately. As shown in FIG. 3 , the conveyor belt 2 according to the second embodiment has a thermoplastic resin layer 11, a canvas layer 12, a thermoplastic resin layer 11B, and a canvas layer 12B laminated in this order. That is, the conveyor belt 2 according to the second embodiment has a canvas layer 12B disposed as the bottom layer, a thermoplastic resin layer 11B laminated on the canvas layer 12B, a canvas layer 12 laminated on the thermoplastic resin layer 11B, and a thermoplastic resin layer 11 laminated on the canvas layer 12.

[0024] The lower thermoplastic resin layer 11B preferably has the same configuration as the upper thermoplastic resin layer 11 and is preferably formed from the same thermoplastic resin as the thermoplastic resin layer 11 described above. That is, the thermoplastic resin layer 11B is composed of a thermoplastic resin with a glass transition temperature of -30°C or lower, such as an ether-based thermoplastic polyurethane resin, and preferably has a durometer hardness of A85 or lower at -30°C as specified in JIS K7311, and more preferably a durometer hardness of A75 or higher to A79 or lower. Furthermore, the thermoplastic resin layer 11B preferably has a durometer hardness of A75 or higher at 23°C, which corresponds to room temperature. In this case, the thickness of the thermoplastic resin layer 11B is preferably 0.3 mm or higher, similar to the thermoplastic resin layer 11 described above. The thermoplastic resin layer 11B disposed as the lower layer does not necessarily have to have the same configuration as the upper thermoplastic resin layer 11. For example, it may have a thickness different from that of the thermoplastic resin layer 11, or may be formed from a thermoplastic resin different from that of the thermoplastic resin layer 11.

[0025] The lower canvas layer 12B preferably has the same configuration as the upper canvas layer 12, and preferably includes the same woven fabric 120 and impregnated resin portion 123 as the canvas layer 12 described above. Here, the description of the woven fabric 120 and the impregnated resin portion 123 will be omitted as they would be redundant. Note that the canvas layer 12B disposed as the lower layer does not necessarily have to have the same configuration as the upper canvas layer 12; for example, it may have a different thickness dimension from the canvas layer 12, or may be composed of a woven fabric and an impregnated resin portion made of a different material from the canvas layer 12.

[0026] According to the above configuration, the conveyor belt 2 according to the second embodiment can achieve the same functions and effects as the first embodiment. Furthermore, the conveyor belt 2 has two canvas layers 12, 12B, which improves the tensile strength of the entire conveyor belt 2. Therefore, the conveyor belt 2 can be wound around a long distance between the drive pulley DP and the driven pulley TP, even in conveying equipment CM where the distance between the drive pulley DP and the driven pulley TP is large. Furthermore, because the tensile strength of the conveyor belt 2 is improved, it can also convey heavy objects CG.

[0027] In the second embodiment described above, the conveyor belt 2 is described as having two thermoplastic resin layers, 11 and 11B, and two canvas layers, 12 and 12B, stacked alternately. However, the present invention is not limited to this. In another embodiment, the conveyor belt may have three or more thermoplastic resin layers and three or more canvas layers, with the same number of thermoplastic resin layers and canvas layers stacked alternately. Even in this case, the thermoplastic resin layer 11 is provided as the top layer of the conveyor belt.

[0028] (3) Third Embodiment Next, a third embodiment of the present invention will be described. As shown in Fig. 4, the conveyor belt 3 according to the third embodiment has a configuration in which a thermoplastic resin layer 11 and a canvas layer 12 are laminated together, and a thermoplastic resin layer 11B is further provided on the back surface of the canvas layer 12. That is, the conveyor belt 3 has the canvas layer 12 as a core, and the thermoplastic resin layers 11 and 11B are laminated on the front and back surfaces of the canvas layer 12.

[0029] According to the above configuration, the conveyor belt 3 according to the third embodiment can also achieve the same functions and effects as those of the first embodiment. Furthermore, even if the thermoplastic resin layers 11, 11B of the conveyor belt 3 shrink when the temperature changes from a normal temperature environment to a low temperature environment, by laminating the thermoplastic resin layers 11, 11B symmetrically on the front and back surfaces of the canvas layer 12, which serves as the core, the shrinkage of the conveyor belt 3 in a low temperature environment is less likely to be uneven, and warping or the like of the conveyor belt 3 can be prevented in a low temperature environment.

[0030] In the third embodiment, too, it is preferable that the thermoplastic resin layer 11B arranged as the lower layer has the same configuration as the thermoplastic resin layer 11 of the upper layer, but the present invention is not limited to this, and for example, it may have a thickness dimension different from that of the thermoplastic resin layer 11, or may be formed from a thermoplastic resin different from that of the thermoplastic resin layer 11.

[0031] (4) Fourth Embodiment Next, a fourth embodiment of the present invention will be described. As shown in Fig. 5, the conveyor belt 4 according to the fourth embodiment differs from the conveyor belt 2 according to the second embodiment in that a thermoplastic resin layer 11C is further provided on the back surface of the lower canvas layer 12B in the configuration of the conveyor belt 2 according to the second embodiment. In this case, the conveyor belt 4 has a core made of a thermoplastic resin layer 11B and canvas layers 12, 12B respectively laminated on the front and back surfaces of the thermoplastic resin layer 11B, a thermoplastic resin layer 11 is further laminated on the front surface of the upper canvas layer 12, and a thermoplastic resin layer 11C is also laminated on the back surface of the lower canvas layer 12B.

[0032] According to the above configuration, the conveyor belt 4 according to the fourth embodiment can achieve the same functions and effects as those of the second embodiment. In addition, since the conveyor belt 4 includes two canvas layers 12, 12B, the tensile strength of the conveyor belt 4 is improved accordingly, and the conveyor belt 4 can convey heavy objects CG.

[0033] In the fourth embodiment, too, it is preferable that the thermoplastic resin layer 11C arranged as the bottom layer has the same configuration as the upper thermoplastic resin layer 11, but the present invention is not limited to this, and for example, it may have a thickness dimension different from that of the thermoplastic resin layer 11, or may be formed from a thermoplastic resin different from that of the thermoplastic resin layer 11.

[0034] (5) Fifth Embodiment In the first embodiment, the conveyor belt 1 having the thermoplastic resin layer 11 with the conveying surface 1A formed flat was described. However, the present invention is not limited to this. For example, as shown in Fig. 6, the conveyor belt 5 may have a thermoplastic resin layer 51 with a basis weight treatment applied to the conveying surface 5A. The conveyor belt 5 according to the fifth embodiment differs from the first embodiment in that the conveying surface 5A of the thermoplastic resin layer 51 is subjected to a basis weight treatment. Since the canvas layer 12 has the same configuration as in the first embodiment, the description of the canvas layer 12 will be omitted here, and the following description will focus on the thermoplastic resin layer 51.

[0035] The thermoplastic resin layer 51 is formed of the same thermoplastic resin as the thermoplastic resin layer 11 of the first embodiment described above. That is, the thermoplastic resin layer 51 is composed of a thermoplastic resin having a glass transition temperature of -30°C or lower, such as an ether-based thermoplastic polyurethane resin, and preferably has a durometer hardness of A85 or lower at -30°C as defined in JIS K7311, and more preferably a durometer hardness of A75 or higher and A79 or lower. Furthermore, the thermoplastic resin layer 51 preferably has a durometer hardness of A75 or higher at 23°C, which corresponds to room temperature. In this case, the thickness of the thermoplastic resin layer 51 is preferably 0.3 mm or higher, similar to the thermoplastic resin layer 11 described above.

[0036] The surface roughness Rz of the conveying surface 5A, as defined in JIS B0601, is preferably 15 μm or more and 100 μm or less, and more preferably 20 μm or more and 50 μm or less. Here, the surface roughness Rz refers to the 10-point average roughness as defined in JIS B0601, and the surface roughness can be measured, for example, using a Handysurf (trade name: manufactured by Tokyo Seimitsu Co., Ltd.). If the surface roughness Rz exceeds 100 μm, the unevenness of the conveying surface 5A becomes too large, which may easily become the starting point for cracks in the conveying belt 5 in a low-temperature environment of -30°C. If the surface roughness Rz is less than 15 μm, the coefficient of friction of the conveying surface 5A becomes small. As a result, when the conveying belt 5 is inclined, the conveyed object CG may not be able to be held on the conveying surface 5A, which may reduce the conveying efficiency of the conveyed object CG.

[0037] As a method of applying basis weight treatment to the conveying surface 5A, the thermoplastic resin layer 51 is heated to soften it, and then a taffeta roll, cloth roll, or the like is pressed against the surface of the thermoplastic resin layer 51, thereby forming an uneven conveying surface 5A having a predetermined surface roughness.

[0038] According to the above configuration, the conveying belt 5 according to the fifth embodiment can also achieve the same functions and effects as those of the first embodiment. Furthermore, in the conveying belt 5, by forming the conveying surface 5A having a surface roughness Rz of 15 μm or more and 100 μm or less on the surface of the thermoplastic resin layer 51, it is possible to reduce the possibility of cracks starting to occur in a low-temperature environment, and it is also possible to more reliably prevent the conveyed object CG from slipping on the conveying belt 5, thereby improving the conveying efficiency of the conveyed object CG.

[0039] (6) Sixth Embodiment Next, a sixth embodiment of the present invention will be described. As shown in Fig. 7, a conveyor belt 6 according to the sixth embodiment has a structure in which a canvas layer 12 is used as a core, and thermoplastic resin layers 51, 51B are laminated on the front and back surfaces of the canvas layer 12. In addition to this structure, the conveyor belt 6 has a conveying surface 5A in which the upper thermoplastic resin layer 51 has been subjected to a basis weight treatment, and a back surface 5B in which the lower thermoplastic resin layer 51 has also been subjected to a basis weight treatment.

[0040] The lower thermoplastic resin layer 51B preferably has the same configuration as the upper thermoplastic resin layer 51 and is preferably formed from the same thermoplastic resin as the thermoplastic resin layer 51 described above. That is, the thermoplastic resin layer 51B is formed from a thermoplastic resin having a glass transition temperature of -30°C or lower, such as an ether-based thermoplastic polyurethane resin, and preferably has a durometer hardness of A85 or lower at -30°C as specified in JIS K7311, and more preferably a durometer hardness of A75 to A79. The thickness of the thermoplastic resin layer 51B is preferably 0.3 mm or greater, similar to the thermoplastic resin layer 51 described above. Note that the thermoplastic resin layer 51B disposed as the lower layer does not necessarily have to have the same configuration as the upper thermoplastic resin layer 51. For example, it may have a different thickness from the thermoplastic resin layer 51 or may be formed from a different thermoplastic resin than the thermoplastic resin layer 51.

[0041] According to the above configuration, the conveyor belt 6 according to the sixth embodiment can achieve the same functions and effects as those of the fifth embodiment. Furthermore, even if the thermoplastic resin layers 51, 51B of the conveyor belt 6 shrink when the temperature changes from room temperature to low temperature, the thermoplastic resin layers 51, 51B are laminated symmetrically on the front and back surfaces of the canvas layer 12, which serves as the core, so that uneven shrinkage of the conveyor belt 6 in low temperature environments is unlikely to occur, and warping of the conveyor belt 6 in low temperature environments can be prevented. Furthermore, the back surface 5B of the other thermoplastic resin layer 51B of the conveyor belt 6 is also subjected to a basis weight treatment, which improves the frictional force against the pulleys DP, TP of the conveyor equipment CM, suppresses slippage on the pulleys DP, TP, and improves the conveying efficiency of the conveyed goods CG.

[0042] In the sixth embodiment, the conveyor belt 6 is described in which a thermoplastic resin layer 51 having a conveying surface 5A that has been subjected to a basis weight treatment is laminated on the surface of the canvas layer 12, and a thermoplastic resin layer 51B having a back surface 5B that has also been subjected to a basis weight treatment is laminated on the back surface of the canvas layer 12. However, the present invention is not limited to this. As a conveyor belt according to another embodiment, for example, a thermoplastic resin layer 11 having a flat conveying surface 1A as shown in FIG. 1 may be laminated as the top layer on the surface of the canvas layer 12, and a thermoplastic resin layer 51B having a back surface 5B that has been subjected to a basis weight treatment may be laminated on the back surface of the canvas layer 12, so that only the back surface 5B of the conveyor belt is subjected to a basis weight treatment.

[0043] (7) Seventh Embodiment Next, a seventh embodiment of the present invention will be described. As shown in Fig. 8, the conveyor belt 7 according to the seventh embodiment has a core made of a thermoplastic resin layer 11B and canvas layers 12, 12B laminated on the front and back surfaces of the thermoplastic resin layer 11B, and further has a configuration in which a thermoplastic resin layer 51 is laminated on the front surface of the upper canvas layer 12 and a thermoplastic resin layer 51B is laminated on the back surface of the lower canvas layer 12B. The upper thermoplastic resin layer 51 has a conveying surface 5A that has been subjected to a basis weight treatment, and the lower thermoplastic resin layer 51B has a back surface 5B that has been subjected to a basis weight treatment.

[0044] The lower thermoplastic resin layer 51B preferably has the same configuration as the upper thermoplastic resin layer 51, and is preferably formed from the same thermoplastic resin as the above-mentioned thermoplastic resin layer 51. The upper canvas layer 12 and the lower canvas layer 12B preferably have the same configuration, and each preferably includes a woven fabric 120 and an impregnated resin portion 123.

[0045] According to the above configuration, the conveyor belt 7 according to the seventh embodiment can achieve the same functions and effects as those of the sixth embodiment. In addition, since the conveyor belt 7 includes two canvas layers 12, 12B, the tensile strength of the conveyor belt 7 is improved, and the conveyor belt 7 can convey heavy objects CG.

[0046] In the seventh embodiment, the core is formed of a thermoplastic resin layer 11B and fabric layers 12, 12B laminated on the front and back surfaces of the thermoplastic resin layer 11B. However, the present invention is not limited to this. For example, the core may be formed by providing two or more thermoplastic resin layers and three or more fabric layers, with the thermoplastic resin layer at the center and fabric layers and thermoplastic resin layers alternately laminated on the front and back surfaces of the central thermoplastic resin layer. Even in this case, the thermoplastic resin layer 51 is provided as the top layer of the conveyor belt, and the thermoplastic resin layer 51B is provided as the bottom layer.

[0047] In the seventh embodiment, the conveyor belt 7 is described in which a thermoplastic resin layer 51 having a conveying surface 5A that has been subjected to a basis weight treatment is laminated on the surface of the canvas layer 12, and a thermoplastic resin layer 51B having a back surface 5B that has also been subjected to a basis weight treatment is laminated on the back surface of the canvas layer 12B. However, the present invention is not limited to this. As a conveyor belt according to another embodiment, for example, a thermoplastic resin layer 11 having a flat conveying surface 1A as shown in FIG. 1 may be laminated as the top layer on the surface of the canvas layer 12, and a thermoplastic resin layer 51B having a back surface 5B that has been subjected to a basis weight treatment may be laminated on the back surface of the canvas layer 12B, so that the basis weight treatment is applied only to the back surface of the conveyor belt.

[0048] (8) Eighth Embodiment Next, an eighth embodiment of the present invention will be described. As shown in Fig. 9, the conveyor belt 8 according to the eighth embodiment has a configuration in which a thermoplastic resin layer 51, a canvas layer 12, a thermoplastic resin layer 11B, a canvas layer 12B, a thermoplastic resin layer 11C, and a canvas layer 12C are laminated in this order, and the uppermost thermoplastic resin layer 51 is subjected to a basis weight treatment to provide a conveying surface 5A. In this case, the conveyor belt 8 has the canvas layer 12C as the lowermost layer, and the pulleys DP and TP of the conveying equipment CM contact the back surface 5B of the canvas layer 12C.

[0049] The upper thermoplastic resin layer 11B and the lower thermoplastic resin layer 11C preferably have the same configuration. Furthermore, the thermoplastic resin layers 11B and 11C are preferably formed from the same thermoplastic resin as the uppermost thermoplastic resin layer 51. The upper canvas layer 12, the middle canvas layer 12B, and the lower canvas layer 12C preferably have the same configuration, and each preferably includes a woven fabric 120 and an impregnated resin portion 123.

[0050] According to the above configuration, the conveyor belt 8 according to the eighth embodiment can achieve the same functions and effects as those of the fifth embodiment. In addition, since the conveyor belt 8 includes three canvas layers 12, 12B, and 12C, the tensile strength of the conveyor belt 8 is improved accordingly, and the conveyor belt 8 can convey heavy objects CG.

[0051] In the eighth embodiment, the core is formed of thermoplastic resin layers 11B, 11C and canvas layers 12, 12B, 12C. However, the present invention is not limited to this. For example, the core may be formed by providing three or more thermoplastic resin layers and four or more canvas layers, with the canvas layer at the center and thermoplastic resin layers and canvas layers alternately stacked on the front and back sides of the central canvas layer. Even in this case, a thermoplastic resin layer 51 is provided as the top layer of the conveyor belt.

[0052] (9) Ninth Embodiment In the above-described first to eighth embodiments, the conveyor belts 1, 2, 3, 4, 5, 6, 7, and 8 were described as conveyor belts each having a thermoplastic resin layer 11, 51 as the uppermost layer, and a canvas layer laminated together at least one thermoplastic resin layer having a durometer hardness of A85 or less as defined in JIS K7311 at -30°C. However, the present invention is not limited thereto. For example, a conveyor belt according to another embodiment may be a conveyor belt having a thermoplastic resin layer having a durometer hardness of A85 or less as defined in JIS K7311 at -30°C and a canvas layer laminated together at least one layer, and a canvas layer laminated together at least one layer, and a canvas layer laminated together at the uppermost layer and the lowermost layer.

[0053] 10, the conveyor belt 9 according to the ninth embodiment has a thermoplastic resin layer 11B as a core, and canvas layers 12, 12B are laminated on the front and back surfaces of the thermoplastic resin layer 11B. The conveyor belt 9 has a conveying surface 9A on the top canvas layer 12, and pulleys DP, TP of the conveying equipment CM contact the back surface 9B of the bottom canvas layer 12.

[0054] The thermoplastic resin layer 11B has the same configuration as the thermoplastic resin layer 11 of the first embodiment described above. That is, the thermoplastic resin layer 11B is made of a thermoplastic resin having a glass transition temperature of −30° C. or lower, such as an ether-based thermoplastic polyurethane resin, and preferably has a durometer hardness of A85 or lower at −30° C. as defined in JIS K7311, and more preferably a durometer hardness of A75 or higher and A79 or lower. The thickness of the thermoplastic resin layer 11B is preferably 0.3 mm or higher.

[0055] The upper canvas layer 12 and the lower canvas layer 12B preferably have the same configuration, and preferably include a woven fabric 120 and an impregnated resin portion 123. Here, the description of the woven fabric 120 and the impregnated resin portion 123 is omitted because it would be redundant. Note that the canvas layer 12B disposed as the lower layer does not necessarily have to have the same configuration as the upper canvas layer 12, and for example, it may have a different thickness dimension from the canvas layer 12, or may be composed of a woven fabric and an impregnated resin portion made of a different material from the canvas layer 12.

[0056] According to the above configuration, the conveyor belt 9 of the ninth embodiment is configured by laminating a thermoplastic resin layer 11B having a durometer hardness of A85 or less as defined in JIS K7311 at -30°C and canvas layers 12 and 12B. As a result, the conveyor belt 9, like the first embodiment, can maintain flexibility even in low-temperature environments without hardening, reducing the possibility of damage to the motor and pulleys DP and TP of the conveyor equipment CM. Furthermore, the conveyor belt 9 has a conveying surface 9A in the upper canvas layer 12 and a back surface 9B in the lower canvas layer 12B that contacts the motor and pulleys DP and TP of the conveyor equipment CM. The canvas layers 12 and 12B create an uneven conveying surface 9A and a back surface 9B. Therefore, the conveyor belt 9 has an uneven surface that makes the conveying surface 9A and the back surface 9B less slippery and less susceptible to wear due to the woven fabric 120.

[0057] (10) Tenth Embodiment Next, a tenth embodiment of the present invention will be described. As shown in Fig. 11, a conveyor belt 10 according to the tenth embodiment has a configuration in which a canvas layer 12B is used as a core, and thermoplastic resin layers 11B, 11C are laminated on the front and back surfaces of the canvas layer 12B. In addition, the conveyor belt 10 has a configuration in which a canvas layer 12 having a conveying surface 9A is laminated on the front surface of the upper thermoplastic resin layer 11B, and a canvas layer 12C having a back surface 9B is laminated on the back surface of the lower thermoplastic resin layer 11C.

[0058] The upper thermoplastic resin layer 11B and the lower thermoplastic resin layer 11C preferably have the same configuration, and are preferably formed from the same thermoplastic resin as the thermoplastic resin layer 11 of the first embodiment described above. The upper canvas layer 12, the middle canvas layer 12B, and the lower canvas layer 12C preferably have the same configuration, and each preferably includes a woven fabric 120 and an impregnated resin portion 123.

[0059] According to the above configuration, the conveyor belt 10 according to the tenth embodiment can achieve the same functions and effects as those of the ninth embodiment. In addition, the conveyor belt 10 is provided with three layers, namely, the canvas layers 12, 12B, and 12C, and these canvas layers 12, 12B, and 12C further improve the tensile strength of the conveyor belt 10, making it possible to convey heavy objects CG.

[0060] (11) Other Embodiments The present invention is not limited to the above-described embodiments, and includes the following modifications: The conveyor belt may be a conveyor belt configured by laminating at least one thermoplastic resin layer having a durometer hardness of A85 or less as defined in JIS K7311 at -30°C and one or more canvas layers, and may be, for example, a conveyor belt that combines the configurations of the first to tenth embodiments described above.

[0061] In addition, as another embodiment of the first to tenth embodiments described above, for example, a conveying belt may be formed by laminating thermoplastic resin layers 11, 11B, 11C, 51, 51B and canvas layers 12, 12B, 12C with another functional resin layer, such as a conductive resin layer, interposed therebetween. Furthermore, in the first, second, sixth, and eighth embodiments, the surfaces of the thermoplastic resin layers 11, 51 are the conveying surfaces 1A, 5A, and the surface of the canvas layer 12 is the back surface of the conveying belt (the surface contacting the pulleys DP, TP) 1B, 5B. However, the present invention is not limited thereto. The surfaces of the thermoplastic resin layers 11, 51 may be the back surface of the conveying belt (the surface contacting the pulleys DP, TP), and the surface of the canvas layer 12 may be the conveying surface. Other specific structures and shapes, etc., may be used when implementing the present invention as long as the object of the present invention can be achieved.

[0062] 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Conveying belt 11, 11B, 11C, 51, 51C Thermoplastic resin layer 12, 12B, 12C Canvas layer 1A, 5A, 9A Conveying surface

Claims

1. A conductive conveyor belt, comprising at least one laminate of a thermoplastic resin layer having a durometer hardness of A85 or less at -30°C as specified in JIS K7311 and a canvas layer.

2. The conveyor belt according to claim 1, wherein the thermoplastic resin layer has a durometer hardness of A75 or more at 23° C. as defined in JIS K7311.

3. The conveyor belt according to claim 1, wherein the thermoplastic resin layer has a glass transition temperature of -30°C or lower.

4. The conveyor belt according to any one of claims 1 to 3, wherein the conveying surface of the conveyor belt has a surface roughness Rz, as defined in JIS B0601, of 15 µm or more and 100 µm or less.

5. The conveyor belt according to any one of claims 1 to 3, wherein a conveying surface of the conveyor belt is the canvas layer.

Images