Seat structure and belts

Abstract

To provide a sheet structure and a belt having high heat resistance and chemical resistance and high degree of design freedom.SOLUTION: Provided is a sheet structure provided with a base material having a first main surface and a second main surface on the reverse side of the first main surface, and a protrusion provided on at least one of the first main surface and the second main surface. The base material includes a woven fabric containing heat-resistant fibers and a first fluororesin for covering at least a part of a surface of the woven fabric. The protrusion includes a second fluororesin and is porous. A belt provided with the sheet structure is also provided.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a seat structure and a belt. [Background technology]

[0002] Conveyor belts and other conveyor belts are used not only in the manufacture of various products but also in various fields such as the logistics industry. In order to prevent the belt from meandering, a cord (e.g., braided cord) or a stainless steel pin is generally attached (fixed) to the roll contact surface of the belt to serve as a meandering prevention guide. A roll or pulley on which the belt is attached is provided with a groove on the outer periphery, and the belt is attached so that the position of the attached cord or pin and the position of the groove are aligned. Since the cord or pin follows the groove during belt running, the belt can run stably with less meandering. Note that the cord or pin may be directly attached to the belt base material, but since there is a possibility that the attachment part (fixing part) may deteriorate due to the belt running, the attachment part may be reinforced. A specific example of reinforcement is ear reinforcement.

[0003] Also, in order to prevent objects placed on the belt from falling or to fix the position, there is a method of attaching (fixing) fabric, fluororesin film, cord, etc. to the belt surface to make a crosspiece, for example. In this case, there is a possibility that the attachment part (fixing part) may deteriorate, so for example, the attachment part may be reinforced by providing ear reinforcement.

[0004] Examples of belts equipped with meandering prevention guides will be described with reference to Figures 16 to 19. In each figure, the longitudinal direction in which the belt travels, i.e., the machine direction (MD), is shown as the Y-axis direction, the transverse direction (TD) is shown as the X-axis direction, and the thickness direction is shown as the Z-axis direction.

[0005] 16 and 17 show an example of a belt with a cord-type belt guide. The illustrated belt 30 includes a belt body including a belt base material 31 and a reinforcing portion 10 consisting of a reinforcing member 11 provided in the vertical direction at both ends of the belt base material 31, and a cord 32 provided in the vertical direction on one of the reinforcing portions 10. The cord 32 may be provided on both reinforcing portions 10, or the reinforcing portion 10 may be omitted. The cord 32 is fixed to the belt body by a sewing thread 35. As shown in FIG. 17, the sewing thread 35 penetrates the belt base material 31, the portion of the reinforcing member 11 that is interposed between the belt base material 31 and the cord 32, and the cord 32 in the thickness direction. Although no example is shown, the sewing thread 35 may penetrate not only the portion of the reinforcing member 11 on one side of the belt base material 31 (the lower side in FIG. 17) but also the portions on both sides of the belt base material 31, that is, the sewing thread 35 may penetrate the entire reinforcing portion 10 in the thickness direction.

[0006] The reinforcing portion 10 is provided to reinforce the belt since the sewing thread 35 penetrates the belt base material 31 when the cord 32 is attached, and the portion where the cord 32 is attached may be damaged and broken during belt running. As mentioned above, the reinforcing portion 10 may be omitted.

[0007] The cord 32 is, for example, a braided cord made of aramid fiber. The sewing thread 35 is, for example, a thread made of aramid fiber, a thread made of glass fiber, a thread made of carbon fiber, or a thread made of fluororesin. A dispersion of fluororesin is applied to the cord 32 before it is attached to the belt body. The dispersion of fluororesin is, for example, a liquid in which a fluororesin such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinylether copolymer resin (PFA), or tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP) is dispersed in water. The cord 32 is sewn to the belt base material 31 using the sewing thread 35, and then molded into a shape by heat pressing.

[0008] 17, the cord 32 provided on the main surface facing the pulley 22 can function as a belt guide to prevent meandering. When the belt 30 is running, the cord 32 runs along a groove 23 provided on the outer circumferential surface around the rotation axis c of the pulley 22, thereby suppressing meandering of the belt 30.

[0009] A specific example is the meandering prevention cord described in Patent Document 1 (Utility Model No. 30226211). The meandering prevention cord includes a core made of thin threads made of aramid fibers and a braided body provided on the outer periphery thereof, which is made by alternately braiding S-stranded threads and Z-stranded threads made of aramid fibers. Furthermore, PTFE is applied to the core and braided body. Patent Document 2 (JP Patent Publication 5-162832) describes a fluororesin cord used as a meandering prevention liner. The fluororesin cord includes a rod-shaped unsintered portion made of PTFE resin and a sintered portion made of PTFE resin provided on the outer periphery thereof.

[0010] 18 and 19 show an example of a belt with a pin-type belt guide. The belt 30 of this example has a plurality of stainless steel guide pins 33 arranged at regular intervals along the vertical direction on one of the reinforcing parts 10 instead of the cord 32, unlike the previous example. The guide pins 33 may be provided on both reinforcing parts 10, or the reinforcing parts 10 may be omitted. As shown in FIG. 19, the guide pin 33 includes a crimping head 33a and a crimping foot 33b, and is fixed by crimping through a through hole provided in the belt body. The crimping head 33a and the crimping foot 33b do not directly contact the reinforcing member 11, but a washer 36 made of resin such as PTFE is interposed between them. The provision of the washer 36 reduces damage to the reinforcing member 11 and the belt base material 31 caused by metal parts. The periphery of the washer 36 may be fixed to the reinforcing member 11 and the belt base material 31 by sewing.

[0011] 19, a portion of the crimped head 33a of the guide pin 33 protruding from the main surface facing the pulley 22 can function as a belt guide for preventing meandering. When the belt runs, the guide pin 33 runs along a groove 23 provided on the outer circumferential surface around the rotation axis c of the pulley 22, thereby suppressing meandering of the belt 30.

[0012] An example of a belt with crosspieces will be described with reference to Figures 20 and 21. In each figure, the longitudinal direction (MD), transverse direction (TD), and thickness direction of the belt are indicated as the Y-axis direction, the X-axis direction, and the Z-axis direction, respectively.

[0013] 20 and 21 show an example of a belt with a crosspiece. The illustrated belt 30 includes a belt base material 31 and a plurality of crosspieces 34 arranged on the belt base material 31 at regular intervals along the vertical direction. In this example, a fabric or a fluororesin film is folded so that the crosspiece has an inverted T-shape, and is fused to the main surface of the belt base material 31 as a crosspiece. In addition to the example shown in the figure, crosspieces having various shapes, such as triangular and trapezoidal cross sections, are commonly used. The crosspieces 34 are fused to the belt base material 31 via the fluororesin-containing layer 5 obtained after applying a dispersion of a fluororesin such as PTFE, PFA, and FEP to the mounting portion of the crosspiece 34, drying, and baking the dispersion. Alternatively, a molten film of a fluororesin such as PFA and FEP is sandwiched between the belt base material 31 and the crosspiece 34 as the fluororesin-containing layer 5 and fused.

[0014] Alternatively, although no example is shown, a member similar to the cord 32 shown in Figures 16 and 17 can be used as a crosspiece instead of the meandering prevention guide. The cord as a crosspiece is provided on the main surface that becomes the belt conveying surface. The cord as a crosspiece is attached (fixed) in the same manner as in the meandering prevention guide. As with the meandering prevention guide, belt reinforcement may be applied to the portion where the crosspiece is attached.

[0015] The shape and arrangement of the bars are not limited to the above example, and bars of various shapes may be used. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] Utility Model No. 3022611 [Patent Document 2] Japanese Patent Application Publication No. 5-162832 Summary of the Invention [Problem to be solved by the invention]

[0017] The belt substrate may be a heat-resistant substrate made of a woven fabric of heat-resistant fibers such as glass fiber coated with a fluororesin. The fluororesin allows such a heat-resistant substrate to withstand a temperature of, for example, 260° C. and to have chemical resistance.

[0018] For example, a braid made of aramid fiber is used for the cord-type meandering prevention belt guide. Since aramid fiber is a synthetic fiber of resin, the more heat is applied, the more the resin decomposes. Therefore, when the braid made of aramid fiber is used continuously, the heat resistance temperature is 200°C, which does not cover the temperature range in which the belt base material can be used. In addition, there are limitations in terms of chemical resistance, and depending on the usage environment, it deteriorates when exposed to chemicals and lacks durability. There is also a weakness that it cannot be used in ultraviolet (UV) equipment. Furthermore, since it is made of braided fibers, it is difficult to remove dirt when it becomes dirty. In addition, in equipment using a running belt, a pulley with a diameter of about φ75 mm is used, but it is required to minimize the diameter of the pulley as much as possible in order to compact the equipment and reduce the step when transferring the transported goods between belts. With the flexibility of the braid, it is difficult to further reduce the diameter of the pulley. In addition, even if the belt guide is made of a fluororesin molded product with a solid structure, there is a concern that the flexibility is limited and the followability to the small diameter pulley may be insufficient. Braided cords made of aramid fibers are easily worn, producing a lot of aramid fiber wear powder and lint, which act as foreign matter and interfere with quality control.

[0019] In the case of metal pin type belt guides, the contact noise between the pin and the roll or pulley while the belt is running is an issue. In addition, there is a problem that metal wear powder due to the contact becomes foreign matter. Furthermore, metal pins include parts that protrude not only from the back surface of the belt that contacts the roll or pulley but also from the front surface of the belt on which the transported goods are placed (for example, the crimping foot 33b and washer 36 shown in FIG. 19), which can be a constraint.

[0020] Fixing the belt guide requires sewing using aramid fiber threads, etc., which makes it difficult to maintain processing accuracy and increases the number of processing steps. In particular, the guide processing at the site where the belt is used is sometimes done by hand sewing, and in that case, the finish varies depending on the skill of the worker. In addition, because the aramid fiber threads penetrate the belt base material during sewing, holes are made in the fluororesin coating at the guide fixing points. For example, liquids that may contain chemicals, such as processing liquids or leaks from the transported goods, may seep in and deteriorate the woven fabric.

[0021] The materials used for the bars (fabric, fluororesin film, cord, etc.) are hard, and there is little freedom in their workability and shape. Depending on the shape and arrangement of the bars, their hardness can affect the running performance of the belt. Furthermore, contact between the bars and the transported goods can damage the goods (products) or cause foreign matter to get mixed in.

[0022] When attaching (fixing) the cord as a crosspiece, the same material as the cord-type meandering prevention belt guide must be used and the same sewing process must be performed, which poses problems related to the heat resistance, chemical resistance, UV resistance, and processing accuracy mentioned above.

[0023] An object of the present invention is to provide a seat structure and a belt that have high heat resistance and chemical resistance and also have a high degree of freedom in design. [Means for solving the problem]

[0024] According to the embodiment, a sheet body having a first main surface and a second main surface on the back side of the first main surface, and a Porous Polytetrafluoroethylene Cord The sheet body includes a substrate including a woven fabric containing heat-resistant fibers and a first fluororesin coating at least a portion of a surface of the woven fabric. The porous polytetrafluoroethylene cord is a uniaxially stretched product of an extrusion molding of polytetrafluoroethylene fine powder.

[0025] According to an embodiment, there is provided a belt having the above-mentioned sheet structure. The belt has a ring-shaped structure in which ends of the sheet structure are joined together. Effect of the Invention

[0026] The sheet structure and belt having the above-mentioned configuration have high heat resistance and chemical resistance, and also have a high degree of freedom in design. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a perspective view illustrating an example of a seat structure according to an embodiment. [Diagram 2] FIG. 13 is a perspective view illustrating a seat structure according to another embodiment of the present invention. [Diagram 3] FIG. 1 is a perspective view illustrating an example of a belt according to an embodiment. [Figure 4] FIG. 1 is a cross-sectional view illustrating an example of a belt according to an embodiment. [Diagram 5] FIG. 4 is a cross-sectional view illustrating another example of a belt according to an embodiment of the present invention. [Figure 6] FIG. 2 is a cross-sectional view showing an example of an ear reinforcement. [Figure 7] FIG. 13 is a cross-sectional view showing a schematic diagram of another example of an ear reinforcement. [Figure 8] FIG. 13 is a cross-sectional view showing a schematic diagram of yet another example of an ear reinforcement. [Figure 9] FIG. 1 is a cross-sectional view illustrating an example of a sheet structure according to an embodiment. [Figure 10] FIG. 11 is a cross-sectional view illustrating another example of a sheet structure according to an embodiment of the present invention. [Figure 11]FIG. 11 is a cross-sectional view illustrating a schematic configuration of a sheet structure according to another embodiment of the present invention. [Figure 12] FIG. 13 is a plan view illustrating a further example of a seat structure according to an embodiment of the present invention. [Figure 13] FIG. 13 is a side view showing the seat structure shown in FIG. 12 . [Figure 14] FIG. 13 is a plan view illustrating a still further example of a seat structure according to an embodiment of the present invention. [Figure 15] FIG. 15 is a side view showing the seat structure shown in FIG. 14 . [Figure 16] FIG. 1 is a perspective view illustrating an example of a conventional belt. [Figure 17] FIG. 1 is a cross-sectional view that illustrates an example of a conventional belt. [Figure 18] FIG. 13 is a perspective view illustrating another example of a conventional belt. [Figure 19] FIG. 11 is a cross-sectional view that illustrates a schematic diagram of another example of a conventional belt. [Figure 20] FIG. 11 is a plan view illustrating a schematic diagram of still another example of a conventional belt. [Figure 21] FIG. 19 is a schematic side view of the belt shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, the embodiments will be described with reference to the drawings as appropriate. Note that the same reference numerals are used to designate common components throughout the embodiments, and duplicated descriptions will be omitted. Also, each figure is a schematic diagram for explaining the embodiments and for facilitating understanding thereof, and the shapes, dimensions, ratios, etc. may differ from those of the actual device, but these can be appropriately modified in design by taking into consideration the following explanation and known techniques.

[0029] The sheet structure according to the embodiment includes a fluororesin protrusion on at least one of the first main surface of the sheet body and the second main surface behind it, that is, on one or both of the two surfaces of the sheet body. The protrusion can be a guide to prevent meandering and / or a rail to prevent falling.

[0030] An example of such a sheet structure is shown in Fig. 1. In each drawing in which the X-axis, Y-axis, and Z-axis are indicated as in Fig. 1, the Y-axis direction corresponds to the longitudinal direction in which the sheet structure or belt travels, that is, the machine direction (MD), the X-axis direction corresponds to the transverse direction (TD), and the Z-axis direction corresponds to the thickness direction.

[0031] The illustrated sheet structure 1 includes a sheet body including a base material 2 and a reinforcing portion 10 consisting of reinforcing members 11 provided in the vertical direction at both lateral ends of the base material 2, a guide 3 provided in the vertical direction on one of the reinforcing portions 10 on one main surface side of the sheet body, and a plurality of crosspieces 4 arranged at regular intervals on the other main surface of the sheet body. The reinforcing portion 10 can be omitted. The guide 3 and the crosspieces 4 are each fixed to the sheet body by a fluororesin-containing layer 5. Here, the guides 3 and the crosspieces 4 protruding from the main surface of the sheet body are collectively referred to as protrusions.

[0032] The substrate 2 includes a woven fabric containing heat-resistant fibers and a first fluororesin that covers at least a part of the surface of the woven fabric. Examples of heat-resistant woven fabrics include glass fibers, aramid fibers, carbon fibers, and mixtures of two or more selected from these. Glass fibers are non-flammable and have electrical insulation properties. On the other hand, aramid fibers have excellent strength and a certain degree of chemical resistance. Carbon fibers are stronger, lighter, and more conductive than glass fibers.

[0033] The woven fabric may be, for example, a plain weave woven fabric of heat-resistant fibers, or a mesh cloth made of woven rovings of a plurality of heat-resistant fibers. Examples of the mesh cloth include leno weave and twill weave.

[0034] Examples of the first fluororesin include polytetrafluoroethylene (PTFE; tetrafluoroethylene resin), tetrafluoroethylene-perfluoroalkylvinylether copolymer resin (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP). The first fluororesin may be one type or two or more types. The first fluororesin preferably contains PTFE.

[0035] The substrate 2 may contain a filler. The filler is desirably mixed or dispersed in the fluororesin. Examples of the filler include carbon materials, inorganic substances (titanium oxide, boron nitride, silicon oxide, zinc oxide, etc.), and various pigments. One or more types of filler may be used. The form of the filler is not particularly limited, and may be granular, fibrous, acicular, etc.

[0036] The protrusions provided on each of the main surfaces (first and second main surfaces) on both sides of the sheet body, i.e., the guide 3 and the crosspiece 4, contain a second fluororesin. The protrusions may be porous molded products or porous molded products of the second fluororesin. The protrusions may be made porous, for example, by stretching a precursor made of the second fluororesin. The illustrated guide 3 has a square cord and the crosspiece 4 has an inverted T-shape, but the shapes of the protrusions are not limited to those shown in the drawings. In addition to the above, the shapes of the protrusions may be various, such as a round cord, a trapezoid, a tube, etc. Since the protrusions can be obtained by molding or forming the second fluororesin, the degree of freedom in the shapes of the guide 3 and the crosspiece 4 is extremely high.

[0037] Another example of the shape of the protrusion is shown in Fig. 2. In the seat structure 1 shown in the figure, instead of a single rectangular cord-shaped guide, multiple trapezoidal guides 3 are arranged at regular intervals along the vertical direction on one of the reinforcing parts 10.

[0038] Examples of the second fluororesin include fluororesins that can be molded into a porous form, such as PTFE, PFA, and FEP. The second fluororesin may be one type or two or more types. The second fluororesin preferably contains PTFE.

[0039] The fluororesin-containing layer 5 contains a third fluororesin derived from the means for fusing the protrusions onto the main surface of the sheet body. The protrusions can be attached (fixed) by, for example, sandwiching a fluororesin film such as PTFE and FEP between the protrusions and the sheet body and heat fusing them. Alternatively, a dispersion of a fluororesin such as PTFE, PFA, or FEP can be applied to the heat-sealed portion of the sheet body, the protrusions, or both of them, dried, and then heat-sealed after contacting both. The third fluororesin can contain, that is, PTFE, PFA, FEP, etc. The type of the third fluororesin can be one type or two or more types.

[0040] The projections may be attached to the sheet body by sewing instead of fusing. When sewing without fusing, the projections may come into contact with the sheet body directly without the fluororesin-containing layer. From the viewpoint of maintaining the chemical resistance and dirt resistance of the sheet body, it is preferable to fix the projections by fusing without sewing. The projections may be fused and then sewn. For sewing, for example, aramid fiber threads, glass fiber threads, carbon fiber threads, and fluororesin threads can be used. Since the heat resistance temperature of aramid fiber threads is about 200°C, which is lower than the heat resistance temperature of the sheet body (for example, about 260°C), it is preferable to use glass fiber threads, carbon fiber threads, or fluororesin threads. In addition, sewing threads in which the above fiber threads are coated with fluororesin can also be used. After sewing, the shape of the projections may be adjusted by performing a molding process using a hot press.

[0041] The sheet structure 1 can be used, for example, as a belt base material for a belt used in manufacturing products, etc. A specific example of use of the sheet structure 1 will be described as an embodiment of a belt including the sheet structure.

[0042] An example of a belt according to the embodiment is shown in Fig. 3. The illustrated belt 20 includes a sheet structure according to the embodiment. The belt 20 is formed by joining sheet structures in a circular or endless shape.

[0043] There is no particular limitation on the form in which the ends of the belt base material are joined to form the annular structure of the belt 20. The joining method can be appropriately selected from known methods such as a method of partially overlapping both ends of the belt base material (overlap method), a method of butting both end faces (butt method), and a method of overlapping or butting the ends after providing an inclination at the ends (skiver joint method) depending on the installation environment and operating conditions of the belt.

[0044] 3 shows a state in which the belt 20 is attached to a pulley 22. The belt 20 includes a belt body including a substrate 2, a guide 3 provided on one main surface of the belt body, and a plurality of crosspieces 4 arranged at regular intervals on the other main surface of the belt body. The guide 3 and the crosspieces 4 are fixed to the back and front surfaces of the sheet body by a fluororesin-containing layer 5, respectively.

[0045] The guide 3 is provided on the main surface of the belt body, the back surface facing the pulley 22. The guide 3 is aligned along the traveling direction 99 of the belt 20. The guide 3 provided on the main surface facing the pulley 22 functions as a belt guide to prevent meandering.

[0046] With reference to FIG. 4, an overview of how the guide 3 prevents meandering will be described. Here, an example is shown in which a sheet structure having only the guide 3 as a porous protrusion and no crosspiece is used for the belt 20. The guide 3 is provided via a fluororesin-containing layer 5 on the main surface of the belt body facing the outer circumferential surface of the pulley 22 centered on the rotation axis c. The position of the belt 20 in the lateral direction corresponds to the position of the groove 23 provided on the outer circumferential surface of the pulley 22. The guide 3 runs along the groove 23 of the pulley 22 during belt running, thereby suppressing meandering of the belt 20.

[0047] The guide 3 formed of a porous material containing the second fluororesin can be fixed to the belt body (sheet body) by fusion, and does not require sewing processing for attachment. Therefore, as in the examples shown in Figs. 3 and 4, even if the reinforcing part is omitted, there is no need to worry about damage to the fixed part of the guide 3 to the belt body during running. The reinforcing part may be provided, and for example, as in the example belt 20 shown in Fig. 5, the reinforcing part 10 may be provided by sandwiching a reinforcing member 11 between the base material 2 and the guide 3 (and the fluororesin-containing layer 5). When the guide 3 is fixed by sewing, it is desirable to provide the reinforcing part 10 in consideration of the possibility that the belt body is damaged and broken by the belt running. The reinforcing part 10 may also be provided when the guide 3 is fixed by fusion instead of sewing. The reinforcing part 10 exemplified here is formed by wrapping processing described later, but the form of the reinforcing part 10 is not limited to that shown in the figure.

[0048] In addition, when a mesh cloth is used as the woven fabric contained in the substrate, it is desirable to provide a reinforcing portion along the edge of the substrate. In a mesh-type woven fabric, the strength (binding force) of the fluororesin that binds the rovings together is weaker than in a plain weave woven fabric, and the rovings may become unraveled. By providing a reinforcing member on the edge of the substrate, the rovings that constitute the mesh cloth can be prevented from becoming unraveled. In addition, a reinforcing portion may be provided on the mesh cloth in order to secure an area for fusing the protrusions. Examples of the mesh cloth include a mesh cloth in which the rovings are woven with a leno weave and a mesh cloth in which the rovings are woven with a twill weave.

[0049] Specific examples of the reinforcing portion will be described with reference to Figs.

[0050] FIG. 6 shows an example of ear reinforcement by lamination. In lamination, a reinforcing fabric or a reinforcing fluororesin film is fused as a reinforcing member 11 to the front or back surface of the base material 2 to provide a reinforcing portion 10. Here, the reinforcing portion 10 is provided at the ear portion of the base material 2, that is, the end portion in the lateral direction. The position where the reinforcing portion is provided by lamination is not limited to the ear portion. For example, the reinforcing portion can be provided in the center of the base material 2.

[0051] 7 shows an example of reinforcement of the selvedge by wrapping. In the wrapping process, the end of the base material 2 is wrapped with a reinforcing fabric or a reinforcing fluororesin film, etc., and then fused to provide the reinforcing portion 10.

[0052] 8 shows an example in which the edge is reinforced by folding. In the folding process, the edge of the base material 2 is folded to the front side or the back side and fused to provide the reinforcement 10.

[0053] Examples of the reinforcing fabric used in lamination and wrapping include glass fiber fabric, aramid fiber fabric, and carbon fiber fabric. The fabric can be appropriately selected depending on the environment in which the sheet structure is used. For example, in an environment exceeding 200°C, glass fiber or carbon fiber fabric is preferable as a reinforcing fabric because it has no such concerns, compared to aramid fiber fabric, which has a concern about the heat resistance temperature limit (200°C) due to heat shrinkage. However, aramid fiber is superior in terms of bending fatigue, and it is preferable to use aramid fiber, which has a higher strength retention rate in an environment of 200°C or less, as a reinforcing fabric. Examples of the reinforcing film include PTFE skiving film and unsintered PTFE film. The unsintered PTFE film is a material used in sealing tape, and becomes sintered when fusion is performed.

[0054] The fusion can be performed, for example, by applying a dispersion of fluororesin such as PTFE, PFA, or FEP to the reinforcing portion, drying the dispersion, and then baking (firing). Alternatively, a molten film of fluororesin such as PFA or FEP is sandwiched between the substrate and the reinforcing member, and fusion is performed.

[0055] The position of the protrusion as a meandering prevention belt guide is not particularly limited. For example, the belt guide may be provided near the end of the sheet structure or belt in the horizontal direction, or in the center. The number of rows of belt guides along the vertical direction of the sheet structure or belt is not limited to one row. For example, two or more rows of belt guides may be provided on one main surface of the sheet body. The position and number of rows of belt guides are appropriately set according to the roll or pulley side portion such as a groove that functions as a meandering prevention mechanism together with the belt guide.

[0056] Specific examples will be described with reference to Figures 9 to 11. Figures 9 to 11 show examples in which the reinforcing parts are omitted, but in any case, for example, ear reinforcement may be provided along one or both ends in the horizontal direction. Also, belt guides may be provided on one or both reinforcing parts.

[0057] 9 shows a sheet structure 1 in which a row of guides 3 is provided at a position close to one end of the substrate 2 in the horizontal direction. The value of the width W from the end of the substrate 2 to the installation position of the guides 3 is not particularly limited, but a specific example is 15 mm. Note that in this example, the center position of the guides 3 is shown as the installation position of the guides 3.

[0058] 10 shows a sheet structure 1 in which two rows of guides 3 are provided at positions close to both lateral ends of a base material 2. A width W1 from one end of the base material 2 to an installation position of one guide 3 and a width W2 from the other end to an installation position of the other guide 3 may have the same value or may have different values.

[0059] 11 shows a sheet structure 1 in which a row of guides 3 is provided at the middle position in the horizontal direction of the substrate 2. A width W1 from one end of the substrate 2 to the installation position of the guides 3 and a width W2 from the other end to the center of the guides 3 may have the same value or different values. In other words, the installation position of the guides 3 may be exactly in the center in the horizontal direction or may be shifted from the center.

[0060] The above describes an example in which a guide and a crosspiece are provided on both sides of the sheet structure (the belt base material of the belt), and an example in which only a guide is provided on one side. However, the sheet structure according to the embodiment also includes a configuration in which only a crosspiece is included as a protrusion.

[0061] 12 and 13 show examples of a sheet structure including only bars as protrusions. The illustrated sheet structure 1 includes a substrate 2 and a plurality of bars 4 provided on one main surface of the substrate 2 via a fluororesin-containing layer 5. The illustrated bars 4 have an inverted T-shape, but the shape of the bars 4 is not limited to that shown in the drawings. For example, as in the examples shown in FIGS. 14 and 15, the sheet structure 1 may include bars 4 having a rectangular prism shape, or may include bars of various other shapes. In the examples shown in FIGS. 12 to 15, the bars 4 are arranged to cross the substrate 2 in the horizontal direction, but the arrangement of the bars 4 is not limited to that shown in the drawings, and may be appropriately set according to, for example, the transported object and the transport route.

[0062] The use of the sheet structure according to the embodiment is not limited to a belt substrate.

[0063] In the seat structure and belt according to the embodiment, the meandering prevention guides, bars, and other protrusions are formed from molded or formed products of a porous fluororesin (second fluororesin), and therefore have the same heat resistance temperature (260°C) as the seat body and belt body. Therefore, they can be used at a continuous use temperature of 260°C. For example, since the aramid fibers used in the belt guides and bars of conventional cord specifications can be eliminated, the heat shrinkage of the aramid fibers can be used in an expanded environment beyond the limit of the cord specifications, which had a continuous use heat resistance temperature of 200°C.

[0064] In addition, the inclusion of the second fluororesin gives the protrusions themselves high chemical resistance. The protrusions are resistant to ultraviolet (UV) rays, making it possible to use the sheet structure and belt in UV equipment. In addition, dirt is less likely to remain on the protrusions.

[0065] Since fluororesin can be molded (formed) into various shapes as protrusions, it is possible to respond to the needs and specifications of the seat structure and belt. For example, in the case of conventional cord types, the dimensions are limited depending on the specifications of the braid, but by molding or processing a new porous material to suit the application, various three-dimensional guides and bars can be easily prepared. In addition, porous protrusions are highly flexible and can exhibit high followability even for small diameter pulleys. Furthermore, protrusions made of porous fluororesin molded products have superior abrasion resistance compared to braids made of aramid fibers, for example. Therefore, not only is durability high, but foreign matter can also be reduced.

[0066] The attachment (fixing) of protrusions to the seat body or belt body does not require reinforcement or sewing, and can be easily attached by heat pressing. It is also flexible, allowing for a high degree of freedom. In addition, while there are cases where the structure of the sewing device makes it impossible to attach to the center of a wide belt with sewing, heat fusion makes it possible to attach directly to the center of the belt. By attaching a meandering prevention guide to the center of the belt, the burden on the belt body caused by the belt travel restriction by the guides on both ends is reduced, and breakdowns due to belt breakage can be reduced.

[0067] Since sewing can be omitted, the number of steps can be reduced and work management can be simplified. In addition, the attachment of the protrusions can be done by hot pressing such as ironing, and by using jigs, it is not dependent on the worker's skill.

[0068] Conventional metal pin type belt guides have problems with the generation and contamination of metal wear powder, but in the case of use as a guide for protrusions according to the embodiment, the use of fluororesin has achieved significant measures against wear powder. Therefore, it is suitable for driving in usage environments where a high level of cleanliness is required. Even when used as a rail, there is little contamination by foreign matter due to contact with the transported object, and the level of cleanliness is extremely high. EXAMPLES

[0069] Examples will be described below, but the embodiments are not limited to the examples described below.

[0070] <Belt running test> [Sample preparation] Example A A PTFE-coated fabric was produced as the substrate for the sheet body as described below. A porous PTFE cord was produced as described below and used for the porous molded product as the protrusions.

[0071] The PTFE-coated fabric was produced as follows. A plain-woven glass fiber fabric was immersed in a PTFE dispersion and then baked. This immersion and baking process was repeated several times to produce a substrate in which the surface of the glass fiber woven fabric was coated with PTFE. The substrate obtained was in the shape of a belt with a thickness of 0.240 mm. The substrate was cut to a size of 290 mm x 917 mm to obtain a sheet body.

[0072] The porous PTFE cord was produced as follows. After adding 18 parts by mass of naphtha (extrusion aid) to 100 parts by mass of PTFE fine powder, the mixture was mixed using a turbulator mixer to prepare a mixture. The mixture was then molded into a cylindrical shape using a preformer. The resulting preform was placed in an extruder. The resulting extrusion molded product was dried in a heating furnace to remove the extrusion aid. The extrusion molded product was uniaxially stretched in the length direction at a temperature below the melting point of PTFE. At this time, the stretching was performed so that the length in the longitudinal direction became about three times its original size. Next, the product was fired to obtain a porous PTFE cord having a rectangular cross-sectional shape of 8 mm x 3 mm.

[0073] The porous PTFE cord was fused to one side of the sheet body so that the center of the cord was located 10 mm from one edge along the long side, to obtain a sheet structure equipped with a meandering prevention guide as a protrusion. A PFA film having a thickness of 25 μm was used for the fusion. Both ends of the sheet body in the longitudinal direction were joined by an overlap method so that the sheet structure was annular, to obtain an endless belt equipped with a meandering prevention belt guide.

[0074] [Evaluation test] A belt running test was carried out on the endless belt using a small shrink wrapping machine PIKO 90-6S manufactured by Daiwa Hytex Co., Ltd. Specifically, the conveyor belt of the PIKO 90-6S was replaced with the endless belt, and a continuous operation test was carried out under the following conditions.

[0075] Test conditions Continuous operation: 20h / day (12,000 flexes / day) x 9 days (total of 108,000 flexes) Roll diameter: φ50 mm x 2 (with groove on one side; approx. 11 mm wide) Traveling speed: 5m / min Temperature: Continuous heating (far infrared heater), bottom heater internal control Belt temperature: Belt surface temperature is around 205℃ (Measured on the surface of the moving belt at the bottom heater installation area inside the device).

[0076] As a result of continuous running under the above conditions, no change in the overall dimensions of the belt was observed, and stable running was confirmed.

[0077] <Peel strength test> [Sample preparation] (Example B1-1) A substrate was prepared in the same manner as in Example A of the running test. The obtained substrate was cut into a size of 50 mm x 180 mm to form a sheet body. In addition, a porous PTFE cord having a rectangular cross-sectional shape of 4 mm x 4 mm was produced in the same manner as in Example A, except that the shape and size of the die installed in the extruder were changed and weak stretching was performed so that the length in the longitudinal direction was about twice that of the original length.

[0078] The porous PTFE cord was fused to one side of the sheet body along the long side at the center of the short side to obtain a sheet structure with protrusions. However, one end of the cord was left unfused to the sheet body. A PFA film having a thickness of 25 μm was used for the fusion.

[0079] Five samples of the sheet structure were prepared using the above procedure.

[0080] (Example B1-2) Five samples of the sheet structure were prepared in the same manner as in Example B1-1, except that when producing the porous PTFE cord, the stretching strength was increased so that the length in the longitudinal direction was about three times larger.

[0081] (Example B1-3) Five samples of the sheet structure were prepared in the same manner as in Example B1-1, except that when producing the porous PTFE cord, the stretching strength was increased so that the length in the longitudinal direction was increased by about five times.

[0082] (Example B1-4) A substrate was prepared in the same manner as in Example A of the running test. The obtained substrate was cut into a size of 50 mm x 180 mm to form a sheet body. A porous PTFE cord was also produced in the same manner as in Example A.

[0083] The porous PTFE cord was fused to one side of the sheet body along the long side at the center of the short side to obtain a sheet structure with protrusions. However, one end of the cord was left unfused to the sheet body. A PFA film having a thickness of 25 μm was used for the fusion.

[0084] Five samples of the sheet structure were prepared using the above procedure.

[0085] (Examples B2-1 to B2-4) Five samples of the sheet structure were prepared using the same procedures as in Examples B1-1 to B1-4, except that instead of using a PFA film to fuse the porous PTFE cord to the sheet body, a dispersion of PFA resin was applied to the fusion points.

[0086] (Examples B3-1 to B3-4) Five samples of the sheet structure were prepared using the same procedures as in Examples B2-1 to B2-4, except that the fusion surface of the porous PTFE cord was roughened using abrasive paper before applying the PFA resin dispersion to fuse the porous PTFE cord to the sheet body.

[0087] [Evaluation test] The peel strength of the PTFE cord relative to the sheet body in each sample prepared in Examples B1-1 to B3-4 (hereinafter collectively referred to as Example B) was measured using a method based on the 180-degree peel test specified in Japanese Industrial Standard JIS K 6854-2:1999.

[0088] In the peel strength test for each of the examples B, peeling occurred not between the sheet body and the PTFE cord, but between the woven fabric and the PTFE coating in the sheet body. As shown by this result, the cords fused without sewing were firmly attached to the sheet body.

[0089] <Heat shrinkage test> [Sample preparation] Example C A substrate was prepared in the same manner as in Example A of the running test. The obtained substrate was cut to a size of 70 mm x 800 mm to form a sheet body. A porous PTFE cord was also produced in the same manner as in Example A.

[0090] The porous PTFE cord was fused to one side of the sheet body along the long side at the center of the short side to obtain a sheet structure having protrusions. A PFA film having a thickness of 25 μm was used for the fusion.

[0091] [Evaluation test] The obtained sheet structure was placed in a furnace set at 260°C and held there for 1 hour. After 1 hour had passed, the sheet structure was removed and left at room temperature (about 25°C) for 20 minutes, and the length of the sheet structure in the longitudinal direction was measured after it had cooled. This process of holding in the furnace, cooling and measuring the dimensions was repeated up to three times. The shrinkage rate of the sheet structure each time it was held in the furnace and cooled was calculated relative to its initial length (800 mm) before it was held in the furnace the first time. The results are shown in Table 1 below. Table 1 shows the long side length at each stage and the shrinkage rate relative to the initial length.

[0092] [Table 1]

[0093] As the above results show, there was almost no shrinkage of the sheet structure even in an environment of 260°C. This shows that a continuous use temperature of 260°C could be achieved.

[0094] <Immersion test> [Sample preparation] Example D A substrate was prepared in the same manner as in Example A of the running test. The obtained substrate was cut into a size of 200 mm x 120 mm to form a sheet body. A porous PTFE cord was also produced in the same manner as in Example B1-2 (stretched 3 times, 4 mm x 4 mm cross section).

[0095] The porous PTFE cord was fused to one side of the sheet body along the short side at the center of the longitudinal direction to obtain a sheet structure having protrusions. A PFA film having a thickness of 25 μm was used for the fusion.

[0096] (Comparative Example) A substrate was prepared in the same manner as in the running test of Example A. The obtained substrate was cut to a size of 200 mm x 120 mm to form a sheet body.

[0097] A PFA dispersion was applied to an aramid fiber braid having a cross-sectional shape of 4 mm x 4 mm. Then, the aramid fiber braid was sewn to one side of the sheet body along the short side direction at the center of the longitudinal direction using aramid fiber thread. Thus, a sheet structure was obtained.

[0098] [Evaluation test] One each of the sheet structures produced in Example D and Comparative Example was placed in a shallow metal container. Canola oil or soy sauce was poured into the container, and samples were prepared by immersing the sheet structure according to Example D in canola oil and soy sauce, and samples were prepared by immersing the sheet structure according to Comparative Example in canola oil and soy sauce, respectively. After immersing each sheet structure for 3 days, it was removed from the canola oil or soy sauce and visually observed.

[0099] In the sheet structure obtained in Example D, both the sample immersed in canola oil and the sample immersed in soy sauce had canola oil or soy sauce attached to the surface of the sheet and cord, but no penetration into the substrate was observed. In contrast, in the sheet structure obtained in the comparative example, in addition to surface adhesion, the sample immersed in canola oil had penetration into the substrate over a width of several centimeters around the aramid fiber braid, and the sample immersed in soy sauce had penetration into the substrate over a width of several millimeters around the aramid fiber braid.

[0100] As shown above, if the PTFE coating layer of the sheet body is damaged by the sewing thread, dirt can reach the base material through that point. If protrusions such as cords are attached by fusion rather than sewing, the coating layer on the surface of the base material will not be damaged and the base material can be protected.

[0101] <Soil adhesion test and cleaning ease check> [Sample preparation] Example E A substrate was prepared in the same manner as in Example A of the running test. The obtained substrate was cut into a size of 200 mm x 120 mm to form a sheet body. In addition, a porous PTFE cord having a rectangular cross-sectional shape of 4 mm x 4 mm was produced in the same manner as in Example A, except that the shape and dimensions of the die installed in the extruder were changed.

[0102] The porous PTFE cord was fused to one side of the sheet body along the short side at the center of the longitudinal direction to obtain a sheet structure having protrusions. A PFA film having a thickness of 25 μm was used for the fusion.

[0103] (Comparative Example) A sheet structure was prepared in the same manner as in the comparative example of the above immersion test.

[0104] [Evaluation test] (dirt adhesion test) Water (150 ml) was added to hot cake mix (Morinaga & Co., Ltd.; 150 g) and stirred until homogenous. In addition, food coloring (green) was added to color the mixture green for identification purposes.

[0105] A sample was prepared by piling green hot cake batter on one side of the sheet structure produced in Example E so as to partially cover the PTFE cord. In addition, a sample was prepared by piling green batter on the opposite side so as to partially cover the back side of the fused surface of the PTFE cord.

[0106] A sample was prepared by piling a green fabric on one side of the sheet structure produced in the comparative example so as to partially cover the aramid fiber braid, and a green fabric was also piling on the other side so as to partially cover the sewing thread.

[0107] Each sheet structure sample with the green dough piled on it was placed in an incubator set at 250°C, left for 15 minutes, then removed from the incubator and cooled to room temperature (about 25°C). Each sheet structure sample with the green dough piled on it was placed in an incubator set at 250°C, baked for 20 minutes, then removed from the incubator and cooled to room temperature (about 25°C).

[0108] The baked green mass was then physically removed from each side of each cooled sheet structure and visually inspected for staining, the results of which are shown in Table 2 below.

[0109] [Table 2]

[0110] (Ease of cleaning confirmed) Next, the ease of cleaning the residue after peeling off the green mass of each sample baked for 20 minutes was confirmed as follows. The back side of the sheet structure of each sample opposite to the side on which the cord or aramid braid was attached (i.e., the conveying surface in the case of a belt) was cleaned with a Kimwipe moistened with alcohol, and the degree of remaining deposits was compared. The sheet surface of the sample according to Example E could be cleaned cleanly, but a small amount of deposits remained on the threads of the sewing threads of the comparative example.

[0111] From the above results, it can be seen that by replacing the braided cord made of aramid fibers or the like with a porous fluororesin cord, it is possible to reduce the adhesion of dirt to both sides of the substrate and improve the ease of cleaning.

[0112] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. The invention as originally claimed in the present application is set forth below. [1] A sheet body including a substrate including a woven fabric including a heat-resistant fiber and a first fluororesin that covers at least a portion of a surface of the woven fabric, and having a first main surface and a second main surface on the back side of the first main surface; a porous protrusion including a second fluororesin provided on at least one of the first main surface and the second main surface; A seat structure comprising: [2] The sheet structure according to [1], wherein the first fluororesin includes at least one selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, and tetrafluoroethylene-hexafluoropropylene copolymer resin. [3] The sheet structure according to [1] or [2], wherein the second fluororesin includes one or more selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, and tetrafluoroethylene-hexafluoropropylene copolymer resin. [4] The sheet structure according to [1] or [2], further comprising a fluororesin-containing layer between the sheet body and the protrusions, the fluororesin-containing layer containing a third fluororesin. [5] A sheet structure according to [1] or [2], A belt having a ring-shaped structure in which the ends of the sheet structure are joined together. [Explanation of symbols]

[0113] 1...sheet structure, 2...base material, 3...guide, 4...crosspiece, 5...fluororesin-containing layer, 10...reinforcing portion, 11...reinforcing member, 20...belt, 22...pulley, 23...groove, 30...belt, 31...belt base material, 32...cord, 33...guide pin, 33a...rivet head, 33b...rivet foot, 34...crosspiece, 35...sewing thread, 36...washer, 99...traveling direction.

Claims

1. A sheet body including a substrate including a woven fabric including a heat-resistant fiber and a first fluororesin that covers at least a portion of a surface of the woven fabric, the sheet body having a first main surface and a second main surface on the back side of the first main surface; a porous polytetrafluoroethylene cord provided on at least one of the first main surface and the second main surface, the porous polytetrafluoroethylene cord being a uniaxially stretched product of an extrusion molding of polytetrafluoroethylene fine powder; A seat structure comprising:

2. 2. The sheet structure according to claim 1, wherein the first fluororesin comprises at least one selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkylvinylether copolymer resin, and tetrafluoroethylene-hexafluoropropylene copolymer resin.

3. 3. The sheet structure according to claim 1, further comprising a tetrafluoroethylene-perfluoroalkylvinylether copolymer resin film between the sheet body and the porous polytetrafluoroethylene cord.

4. A sheet structure as described in claim 1 or 2, further comprising a fluororesin-containing layer between the sheet body and the porous polytetrafluoroethylene cord and made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin.

5. The seat structure according to claim 1 or 2 is provided. A belt having a ring-shaped structure in which the ends of the sheet structure are joined together.

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