Conveyor belt

Abstract

To provide a conveyor belt capable of reducing environmental load compared to the conventional art.SOLUTION: A conveyor belt 10 includes: a belt body 12 formed of a resin composition; and a conductive resin layer 14 provided on a surface 12b opposite to a conveying surface 12a of the belt body 12, where the resin composition includes a thermoplastic polyurethane resin containing a biomass-derived component. The conveyor belt 10 contains the thermoplastic polyurethane resin containing the biomass-derived component, thereby reducing the use of a petrochemical-derived component. Thus, it can reduce environmental load compared to the conventional art.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conveyor belts are used for transporting various objects or objects such as cardboard boxes containing objects. The conveyor belt is stretched around a plurality of rollers provided on a roller conveyor, for example, and moves the objects by running in at least one direction. As such a conveyor belt, a configuration using a belt body formed of a thermoplastic polyurethane resin has been conventionally known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-104875 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because thermoplastic polyurethane resins are composed of petrochemically derived components (components derived from fossil fuels), there are concerns about their use in the future due to the growing awareness of the need to reduce the use of petroleum, which is a dwindling resource.In addition, petrochemically derived resin products emit large amounts of carbon dioxide when incinerated, so there are concerns about the burden they place on the global environment.

[0005] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a conveyor belt that can reduce the environmental load compared to conventional conveyor belts. [Means for solving the problem]

[0006] The conveyor belt of the present invention has a belt body formed of a resin composition and a conductive resin layer provided on the surface of the belt body opposite to the conveying surface, and the resin composition contains a thermoplastic polyurethane resin containing a biomass-derived component. Effect of the Invention

[0007] According to the present invention, the use of petrochemically derived components can be reduced, and therefore the environmental load can be reduced accordingly compared to conventional methods. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a configuration of a conveyor belt according to an embodiment of the present invention. [Diagram 2] 1 is a graph showing the relationship between load and elongation obtained from a tensile test. [Diagram 3] 1 is a graph showing the relationship between load and elongation obtained from a tensile test for a conveyor belt using an ester-based thermoplastic polyurethane resin containing a biomass-derived component in the belt body and a conveyor belt using an ester-based thermoplastic polyurethane resin made of a petroleum-derived component. [Figure 4] FIG. 4 is a partially enlarged view of FIG. [Diagram 5] 1 is a graph showing the relationship between load and elongation obtained from a tensile test for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ester-based thermoplastic polyurethane resin sheet made of a petroleum-derived component. [Figure 6] FIG. 6 is a partially enlarged view of FIG. 5. [Figure 7] 1 is a graph showing the relationship between load and elongation obtained from a tensile test for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component. [Figure 8] FIG. 8 is a partially enlarged view of FIG. [Figure 9]1 is a graph showing the change in hardness (JIS-A) of an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component, an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component, and an ester-based thermoplastic polyurethane resin sheet made of a petrochemical-derived component before and after immersion in an aqueous sodium hypochlorite solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment of the present invention will now be described in detail with reference to the drawings.

[0010] (1)<Conveyor belt configuration> As shown in FIG. 1, the conveyor belt 10 according to the present embodiment has a configuration in which a belt body 12 and a conductive resin layer 14 are superimposed. In this case, the conveyor belt 10 has a conductive resin layer 14 laminated on a surface 12b opposite to the conveying surface 12a of the belt body 12. The conveyor belt 10 is an endless belt with both ends joined together, and is stretched around a plurality of rollers provided on a roller conveyor, for example, and runs in one direction by the rotation of the rollers. When the conveyor belt 10 is used by being stretched around the rollers, the stretch range required for the conveyor belt 10 is about 1 to 5% and the tension in this stretch range is important. As described above, the conveyor belt 10 used for the roller conveyor needs to have a certain degree of stretch, and therefore it is desirable that the conveyor belt 10 be made of only resin.

[0011] One surface of the belt body 12 is a conveying surface 12a that comes into contact with the object to be conveyed. The conveyor belt 10 conveys the object in the traveling direction, for example, by running in one direction with the object placed on the conveying surface 12a. Note that the conveyor belt 10 may also convey the object by running in a state in which the object is sandwiched between the conveyor belt 10 and the conveying surface of another conveyor belt that runs parallel to the conveyor belt 10.

[0012] The conveyor belt 10 according to this embodiment is given tensile strength by the belt body 12. For this reason, the thickness of the belt body 12 is made larger than the thickness of the conductive resin layer 14. The conductive resin layer 14 has small irregularities formed on a surface 14a opposite to the surface in contact with the belt body 12, and these irregularities increase the frictional force with the rollers.

[0013] The thickness of the conveyor belt 10 is preferably 0.5 mm or more and 3.0 mm or less, taking into consideration the conveying ability of stably conveying an object placed on the conveying surface 12a of the conveyor belt 10. The conductive resin layer 14 is not limited in color or thickness as long as it has conductivity, but is formed to be smaller than the thickness of the belt main body 12. In this example, when the thickness of the belt main body 12 is 1.0 mm, the thickness of the conductive resin layer 14 is about 0.05 mm (0.2 mm including the unevenness of the surface 14a).

[0014] (2) <Belt body> The belt body 12 is formed of a resin composition containing a thermoplastic polyurethane resin containing a biomass-derived component. "Biomass-derived" means that the biomass-derived material is a renewable organic resource (plant or animal-derived) excluding fossil resources.

[0015] In addition to the thermoplastic polyurethane resin containing the biomass-derived component, the resin composition containing the thermoplastic polyurethane resin may appropriately contain, for example, a pigment, a reinforcing agent, a filler, an antioxidant, a plasticizer, an ultraviolet absorber, a flame retardant, a solvent, a surfactant (including a leveling agent), a dispersant, a dehydrating agent, a rust inhibitor, an adhesion promoter, an antistatic agent, a processing aid, a hydrolysis inhibitor, etc. Also, the thermoplastic polyurethane resin containing the biomass-derived component may be used alone as the resin composition.

[0016] Thermoplastic polyurethane resins containing biomass-derived components include ether-based and ester-based resins, and are particularly preferably ester-based. Ester-based thermoplastic polyurethane resins containing biomass-derived components have higher tear resistance and oil resistance than ether-based thermoplastic polyurethane resins containing biomass-derived components. For this reason, the conveyor belt 10 can be used in environments where tear resistance and oil resistance are required by using an ester-based thermoplastic polyurethane resin containing a biomass-derived component as a constituent material of the belt body 12.

[0017] The ester-based thermoplastic polyurethane resin can be obtained by reacting a polyol component and an isocyanate component, and further, if necessary, other components such as a chain extender. The ester-based thermoplastic polyurethane resin has a soft segment made of a polyol component derived from a biomass, and a hard segment made of an isocyanate component derived from a petrochemical.

[0018] The ester-based thermoplastic polyurethane resin preferably contains only a polyol component derived from a biomass-derived component as a polyol component, but may also contain a polyol component derived from a petrochemical component in addition to the polyol component derived from a biomass-derived component. The ester-based thermoplastic polyurethane resin according to this embodiment contains a polyester polyol derived from a biomass-derived component as a polyol component. Examples of the polyester polyol derived from a biomass-derived component include short-chain diols and polyols derived from plants such as castor beans (castor bean seeds).

[0019] The isocyanate component contained in the ester-based thermoplastic polyurethane resin may be an isocyanate component derived from a biomass or a petrochemically derived isocyanate component.

[0020] Examples of the isocyanate component include aliphatic polyisocyanates and alicyclic polyisocyanates. Examples of the aromatic polyisocyanates include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylene diisocyanate (XDI), and naphthalene diisocyanate (NDI). Examples of the aliphatic polyisocyanates include hexamethylene diisocyanate (HDI). Examples of the alicyclic polyisocyanates include isophorone diisocyanate (IPDI). Examples of the isocyanate component that can be used include polyisocyanates modified with carbodiimide (carbodiimide-modified polyisocyanates), isocyanurate-modified polyisocyanates, and urethane prepolymers (for example, reaction products of polyols and excess polyisocyanates having isocyanate groups at the molecular terminals). These may be used alone as the isocyanate component, or two or more of them may be used in combination.

[0021] The biomass ratio of the belt body 12 according to the present embodiment is preferably 10 wt% or more and 95 wt% or less. By making the biomass ratio 10 wt% or more, it is possible to suppress petrochemical-derived components and reduce the environmental load.

[0022] Furthermore, from the viewpoint of hardness (JIS-A), the biomass degree of the belt body 12 is more preferably 50 [wt%] or more and 70 [wt%] or less. Here, in order to stably transport the transported object placed on the transport surface 12a of the transport belt 10, the belt body 12 desirably has a hardness of 80 (JIS-A) or more and 90 (JIS-A) or less as required in accordance with JIS K7311. Since the hardness of the ester-based thermoplastic polyurethane resin containing a biomass-derived component is 80 (JIS-A) and the biomass degree is about 70 [wt%], and the hardness is 90 (JIS-A) and the biomass degree is about 50 [wt%], from the viewpoint of hardness (JIS-A), the biomass degree is more preferably 50 [wt%] or more and 70 [wt%] or less.

[0023] The biomass degree of the belt body 12 can be determined from the weight ratio of the components based on the biomass degree specified for each component contained in the resin composition. If the belt body is manufactured only from a thermoplastic polyurethane resin consisting only of petrochemically derived components, the biomass degree of the belt body is 0% since no biomass-derived components are contained in the belt body. Note that the biomass degree of the belt body 12 can also be determined by calculating the content of biologically derived radiocarbon in the belt body 12 by radiocarbon measurement, since fossil resources such as petroleum do not contain radioactive carbon (C14).

[0024] The biomass content of the belt body 12 can be adjusted, for example, by adjusting the content of the ester-based thermoplastic polyurethane resin containing a biomass-derived component in the resin composition constituting the belt body 12, or by adjusting the content of the polyol component of the biomass-derived component or the isocyanate component of the biomass-derived component, which are components of the ester-based thermoplastic polyurethane resin.

[0025] (3) <Conductive resin layer> The conductive resin layer 14 is a resin layer to which electrical conductivity has been added, and is provided in order to impart an antistatic effect to the conveyor belt 10. The conductive resin layer 14 is formed by incorporating a conductive filler into a resin of petrochemical origin. In this embodiment, the conductive resin layer 14 is formed by blending carbon black into a thermoplastic polyurethane resin.

[0026] The resin constituting the conductive resin layer 14 is not particularly limited as long as it has abrasion resistance and elasticity. For example, in addition to thermoplastic polyurethane resin made from petrochemical-derived components, vulcanized rubber, polyester elastomer, etc. can also be used.

[0027] The conductive filler is not particularly limited as long as it can be mixed with the resin to provide electrical conductivity. For example, carbon-based fillers such as carbon black, carbon nanotubes, carbon fibers, and graphite, and oxides of iron and copper can be used. In particular, carbon-based conductive fillers are preferred because of their high electrical conductivity. The surface electrical resistance of the conductive resin layer 14 is 10 9 [Ω / □] or less is desirable.

[0028] (4) <Manufacturing method of conveyor belt> The conveyor belt 10 can be manufactured by any method as long as the belt body 12 and the conductive resin layer 14 are not peeled off. For example, when manufacturing by the extrusion lamination method, a conductive resin mixed with molten resin is spread on a cloth material (or release paper, etc.) whose surface has been subjected to a release treatment to form the conductive resin layer 14. A resin composition that is a raw material of the belt body 12 is melted and extruded from an extruder in the form of a film and supplied to the surface of the conductive resin layer 14 on the cloth material, and these are fed to a cooling roller for lamination. The belt body 12 and the conductive resin layer 14 thus integrated are peeled off from the cloth material to obtain the conveyor belt 10.

[0029] (5) <Action and Effects> In the above configuration, the conveyor belt 10 has a belt body 12 formed of a resin composition, and a conductive resin layer 14 provided on a surface 12b opposite to the conveying surface 12a of the belt body 12, and the resin composition contains a thermoplastic polyurethane resin containing a biomass-derived component. By containing the thermoplastic polyurethane resin containing a biomass-derived component, the conveyor belt 10 can suppress the use of petrochemical-derived components, and therefore the environmental load can be reduced compared to conventional methods.

[0030] In addition, the conveyor belt 10 uses an ester-based thermoplastic polyurethane resin containing a biomass-derived component, which has high tear resistance and oil resistance, as the thermoplastic polyurethane resin containing a biomass-derived component contained in the resin composition. This allows the conveyor belt 10 to be used in environments where tear resistance and oil resistance are required, as compared to when an ether-based thermoplastic polyurethane resin is used.

[0031] (6) <Tensile test> <Manufacturing of conveyor belt body> Next, a tensile test was performed on the conveyor belt 10 to examine the relationship between the load and the elongation rate. The conveyor belt 10 of Example 1 was manufactured by an extrusion lamination method. Specifically, a conductive resin composition was obtained by blending a conductive filler with a thermoplastic polyurethane resin made of molten petrochemical-derived components, and the obtained conductive resin composition was spread on a cloth material with a release treatment on the surface to produce a sheet-like conductive resin layer 14 supported on the cloth material. Next, a polyester-based thermoplastic polyurethane resin (manufactured by DIC Covestro Polymer Co., Ltd.) containing a biomass-derived component, which has a biomass content of about 70 [wt%] and a hardness of 80 (JIS-A) required in accordance with JIS K7311, was melted and extruded from an extruder into a film shape and supplied, and the obtained belt main body 12 and the sheet-like conductive resin layer 14 supported on the cloth material were overlapped and sent to a cooling roller to be laminated. Next, the laminate in which the belt body 12 and the conductive resin layer 14 were integrated was peeled off from the fabric material, and the peeled laminate was used as the conveyor belt 10.

[0032] An uneven pattern was generated on the surface of the conductive resin layer 14 due to the traces of the peeled fabric material. The thickness of the belt body 12 was 1.0 [mm], the thickness of the conductive resin layer 14 including the unevenness of the surface 14a was 0.2 [mm], and the thickness of the conveyor belt 10 was 1.2 [mm]. The obtained conveyor belt 10 was cut to prepare a dumbbell-shaped test piece (also called a biomass-derived product) having a width of 10 [mm] and a length of 400 [mm].

[0033] <Elongation rate and load> A tensile test was performed on the biomass-derived product of Example 1 at a tensile speed of 50 [mm / min] using a measuring device (Autograph AGS-5kNG) manufactured by Shimadzu Corporation, and the load [N / mm] and elongation rate [%] were measured. As a result, the results shown in FIG. 2 were obtained. From FIG. 2, for example, in Example 1, the load per 1 [mm] of width of the conveyor belt 10 at an elongation rate of 10 [%] was 1.5 [N / mm] or less. It can be said that the conveyor belt 10 of Example 1 can keep the tension low, and therefore the load applied to the roller around which the conveyor belt 10 is wound can be reduced, and damage to the roller can be prevented.

[0034] (7) <Tensile test of conveyor belts made of different resins> In the same manner as above, a conveyor belt 10 using an ester-based thermoplastic polyurethane resin containing a biomass-derived component for the belt body 12, and a conveyor belt using an ester-based thermoplastic polyurethane resin made of a petrochemical-derived component for the belt body were manufactured. Both belts were similar except for the type of resin used for the belt body.

[0035] The conveyor belts obtained above using different resins for the belt body were subjected to a tensile test in the same manner as above to measure the load [N / mm] and the elongation rate [%]. As a result, the results shown in FIG. 3 were obtained. FIG. 3 shows the relationship between the load [N / mm] and the elongation rate [%] for a conveyor belt 10 using an ester-based thermoplastic polyurethane resin containing a biomass-derived component for the belt body 12 (shown as "biomass-derived (ester-based)" in FIG. 3) and a conveyor belt using an ester-based thermoplastic polyurethane resin made of a petroleum-derived component for the belt body (shown as "petroleum-derived (ester-based)" in FIG. 3). FIG. 4 is an enlarged view of the range of elongation rate of 10% or less in FIG. 3.

[0036] As shown in Figures 3 and 4, when comparing the load versus elongation rate in a range of elongation rate of 10% or less between a conveyor belt 10 using an ester-based thermoplastic polyurethane resin containing a biomass-derived component for the belt body 12 and a conveyor belt using an ester-based thermoplastic polyurethane resin made of petroleum-derived components for the belt body, the load versus elongation rate tends to be similar for both, or the conveyor belt 10 using an ester-based thermoplastic polyurethane resin containing a biomass-derived component for the belt body 12 tends to be lower.

[0037] (8) <Tensile test of different resin sheets 1> An ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ester-based thermoplastic polyurethane resin sheet made of a petrochemical-derived component were prepared.

[0038] A tensile test was carried out on each of the above resin sheets in the same manner as above, and the load [N / mm] and elongation rate [%] were measured. As a result, the results shown in FIG. 5 were obtained. FIG. 5 shows the relationship between the load [N / mm] and elongation rate [%] for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component (shown as "biomass-derived (ester-based)" in FIG. 5) and an ester-based thermoplastic polyurethane resin sheet made of a petroleum-derived component (shown as "petroleum-derived (ester-based)" in FIG. 5). FIG. 6 is an enlarged view of the range of elongation rates of 25% or less in FIG. 5.

[0039] As shown in Figures 5 and 6, when comparing the load versus elongation rate for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ester-based thermoplastic polyurethane resin sheet made of petrochemical-derived components in the range of elongation rates of 25% or less, the load versus elongation rate tends to be similar for both, or the ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component tends to be lower.

[0040] (9) <Tensile test of different resin sheets 2> An ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component were prepared.

[0041] A tensile test was carried out on each of the above resin sheets in the same manner as above, and the load [N / mm] and elongation rate [%] were measured. As a result, the results shown in FIG. 7 were obtained. FIG. 7 shows the relationship between the load [N / mm] and the elongation rate [%] for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component (shown as "biomass-derived (ester-based)" in FIG. 7) and an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component (shown as "biomass-derived (ether-based)" in FIG. 7). FIG. 8 is an enlarged view of the range of elongation rates of 25% or less in FIG. 7.

[0042] As shown in Figures 7 and 8, when comparing the load versus elongation rate between an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component and an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component in an elongation rate range of 25% or less, the ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component tends to have a lower load versus elongation rate.

[0043] (10) <Changes in hardness before and after immersion in sodium hypochlorite solution> In the same manner as described above, an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component, an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component, and an ester-based thermoplastic polyurethane resin sheet composed of a petrochemical-derived component were prepared, and their hardness (JIS-A) was measured before and after immersion in an aqueous sodium hypochlorite solution as follows.

[0044] First, the hardness (JIS-A) of each resin sheet was measured at five points using an MD-1 hardness tester under conditions of a temperature of 23°C and a relative humidity of 50%RH, and the hardness (JIS-A) before immersion in the sodium hypochlorite aqueous solution was determined. Each resin sheet was adjusted so that the hardness (JIS-A) of each resin sheet before immersion in the sodium hypochlorite aqueous solution was about 80.

[0045] Next, each of the above resin sheets was immersed in an aqueous sodium hypochlorite solution having a concentration of 5000 ppm and a temperature of 20° C. for 4 weeks, and the hardness (JIS-A) after immersion in the aqueous sodium hypochlorite solution was determined in the same manner as above.

[0046] 9 is a graph showing the change in hardness (JIS-A) before and after immersion in a sodium hypochlorite aqueous solution for an ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component (shown as "biomass-derived (ester-based)" in FIG. 9), an ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component (shown as "biomass-derived (ether-based)" in FIG. 9), and an ester-based thermoplastic polyurethane resin sheet made of a petrochemical-derived component (shown as "petrochemical-derived (ester-based)" in FIG. 9). In FIG. 9, the hardness before immersion for each resin sheet is shown as 100%. The change in hardness (%) before and after immersion in a sodium hypochlorite aqueous solution for four weeks was about 11% for the ester-based thermoplastic polyurethane resin sheet containing a biomass-derived component, about 14% for the ether-based thermoplastic polyurethane resin sheet containing a biomass-derived component, and about 7% for the ester-based thermoplastic polyurethane resin sheet made of a petrochemical-derived component. The hardness change (%) of the ester-based thermoplastic polyurethane resin sheet containing biomass-derived components before and after immersion in a sodium hypochlorite aqueous solution for four weeks was smaller than that of the ether-based thermoplastic polyurethane resin sheet containing biomass-derived components. [Explanation of symbols]

[0047] 10 Conveyor belt 12 Belt body 12a Conveying surface 14 Conductive resin layer

Claims

1. A belt body formed of a resin composition; a conductive resin layer provided on a surface of the belt body opposite to a conveying surface; A conveyor belt having The resin composition comprises a thermoplastic polyurethane resin containing a biomass-derived component.

2. The thermoplastic polyurethane resin is an ester-based resin. The conveyor belt according to claim 1.

3. The thermoplastic polyurethane resin has a soft segment composed of a polyol component derived from the biomass and a hard segment composed of an isocyanate component derived from a petrochemical component. The conveyor belt according to claim 2.

4. The belt body has a biomass content of 10 wt% or more and 95 wt% or less. The conveyor belt according to claim 2.

5. The load per 1 mm of width of the conveyor belt when the elongation rate of the conveyor belt is 10% is 1.5 N / mm or less. The conveyor belt according to claim 2.

Images