JP7739713B2 - Textile and cable covers for robot arms - Google Patents

Description

The present invention relates to a wear-resistant fabric and a cable cover for a robot arm.

Taking advantage of the low coefficient of friction of fluororesin, sliding fabrics have been developed that improve friction durability by turning fluororesin into fibers and arranging them on the surface of sliding components as woven or nonwoven fabrics. Furthermore, because fluororesin fibers generally have low strength, a technique has been disclosed that improves sliding durability by interweaving fluororesin fibers with fibers stronger than the fluororesin fibers. Examples of such interweaving techniques include double-layered fabrics in which fluororesin fibers are arranged on the sliding surface and fibers other than fluororesin fibers on the non-sliding surface, and fabrics made from composite yarns formed from fluororesin fibers and fibers other than fluororesin fibers.

For example, Patent Document 1 discloses a heat- and wear-resistant multilayer fabric consisting of a sliding fabric containing fluororesin fibers and a base fabric. By optimizing the base surface, the fabric exhibits high heat and wear resistance, ensuring long-term sliding performance even when exposed to high-temperature environments. The PTFE worn away by sliding is absorbed by the entanglement points (bonding points due to entanglement) between the sliding fabric and the base fabric and the sliding surface of the base fabric. A portion of the PTFE coats the entanglement points and the sliding fabric-side surface of the base fabric, while the remaining PTFE accumulates in the uneven portions of the base fabric. Even as the entire multilayer fabric wears away, the PTFE accumulated in the uneven portions of the base fabric continues to coat the base fabric surface, resulting in a continuous PTFE-coated fabric surface, maintaining long-term sliding performance.

Patent document 2 discloses a self-lubricating fabric that includes a composite yarn formed from a fluororesin fiber and another fiber, in which the surface area of the other fiber on one side of the fabric accounts for 0 to 30% of the surface area of the entire composite yarn.

Patent No. 6398189 International Publication No. 2017/020821

The fabric described in Patent Document 1 above was a double-layered fabric in which PTFE fibers and other fibers were separately arranged in a sliding fabric layer and a base fabric layer, respectively. As a result, when exposed to high-speed sliding under a high load, the fluororesin fibers were easily expelled, and there was an issue that sufficient long-term sliding durability could not be achieved.

The self-lubricating fabric described in Patent Document 2 uses a composite yarn made of fluororesin fiber and other fibers, which allows fluorine wear particles to easily transfer to other fibers adjacent to the fluororesin fiber, improving sliding durability under high loads. However, because the proportion of fluororesin fiber in the composite yarn was excessively high compared to the other fibers in order to achieve low friction, the release of wear particles from the fluororesin fiber was not sufficiently suppressed when exposed to high-speed sliding under high loads, leaving room for improvement in long-term sliding durability.

Therefore, the objective of the present invention is to provide a woven fabric that has low friction and can exhibit long-term sliding properties even when subjected to high-speed frictional forces under high loads.

To solve this problem, the present invention has the following configuration.

A woven fabric using a composite yarn of fluororesin fiber A and fiber B other than fluororesin fiber as at least one of the warp and weft yarns, in which the mass ratio α of fluororesin fiber A in the composite yarn is 5 to 70%, and the ratio X/Y of the area ratio X of fluororesin fiber on the surface of the woven fabric to the mass ratio Y of fluororesin fiber in the woven fabric is 1 or more and 5 or less.

The woven fabric is made by using a composite yarn as either the warp or weft yarn, and using fiber B as either the weft or warp yarn perpendicular to the composite yarn.

The woven fabric, wherein the area ratio X is 10% or more and 60% or less.

The above-mentioned woven fabric, wherein the composite yarn is a twisted yarn obtained by twisting together fluororesin fiber A and fiber B other than fluororesin fiber.

The woven fabric in which fiber B constituting the ply-twisted yarn is a twisted yarn.

The woven fabric, wherein the fluororesin fiber A is made of polytetrafluoroethylene resin.

The woven fabric wherein fiber B is a fiber having a tensile strength of 7 cN/dtex or more.

The fabric wherein fiber B is a fiber having a tensile strength of 15 to 50 cN/dtex.

The above-mentioned woven fabric, wherein fiber B is a fiber having a heat resistance temperature of 280°C or higher.

The woven fabric wherein fiber B is a fiber having a tensile modulus of 450 to 800 cN/dtex.

The woven fabric, wherein fiber B is an organic fiber.

The woven fabric, wherein fiber B is a fiber selected from liquid crystal polyester fiber, para-aramid fiber, and polyparaphenylene benzobisoxazole fiber.

A cable cover for a robot arm that uses the above-mentioned fabric in at least part.

The present invention provides a woven fabric that has low friction and can exhibit long-term sliding properties even when subjected to high-speed friction forces under high loads.

The woven fabric of the present invention uses a composite yarn of fluororesin fiber A and a fiber B other than fluororesin fiber in at least one of the warp and weft yarns, and is characterized in that the mass ratio α of fluororesin fiber A in the composite yarn is 5 to 70%, and the ratio of the area ratio X of fluororesin fiber A on the surface of the fabric to the mass ratio Y of fluororesin fiber A in the woven fabric is 1 to 5. By arranging the fluororesin fiber in the woven fabric as a composite yarn with a fiber other than fluororesin fiber, the fluororesin fiber and fiber B are adjacent to each other in the woven fabric, facilitating the transfer of fluorine abrasion powder generated by abrasion of fluororesin fiber A due to sliding to fiber B, forming a self-lubricating film and resulting in excellent wear durability under high loads. Furthermore, for high-speed sliding under high loads, the mass ratio of the fluororesin fiber in the composite yarn, the area ratio of the fluororesin fiber, and the mass ratio of the fluororesin fiber in the woven fabric can be optimized, respectively, so that the fiber other than fluororesin fiber serves as a skeletal fiber to support the woven fabric, thereby achieving long-term sliding performance even when subjected to high-speed frictional forces under high loads.

The woven fabric of the present invention uses a composite yarn of fluororesin fiber A and fiber B other than fluororesin fiber for at least one of the warp and weft. More preferably, the composite yarn is used for either the warp or weft, and fiber B is used for either the weft or warp, which is perpendicular to the composite yarn. This configuration makes it easier to obtain a woven fabric with an appropriate value for X/Y, as described below. Furthermore, an embodiment in which the composite yarn is used for the warp and fiber B is used for the weft is particularly preferred. Since the crimp of weaving yarns is generally larger in the warp and smaller in the weft, this configuration makes it easier for the composite yarn containing fluororesin fiber A to be exposed on the surface of the fabric, and fiber B is arranged linearly in the woven fabric, improving the strength utilization efficiency of fiber B. Note that when the crimp of the weft is larger than that of the warp, it is also preferable to use fiber B for the warp and composite yarn for the weft. When a composite yarn is used for either the warp or weft, it is preferable that the weft or warp, which is perpendicular to the composite yarn, is the same type of fiber as fiber B. The term "same type of fiber" as used herein refers to fibers made of the same polymer, but the number of filaments and fineness do not need to be the same. The term "same polymer" as used herein refers only to the fact that the polymers constituting the fibers are substantially the same, and the presence or absence of additives and the type of additives may be different. Furthermore, "substantially the same" does not necessarily mean strict identicalness; it may refer to a combination of a homopolymer and a copolymer, or a copolymer and another copolymer, as long as the main repeating unit is the same and the resulting woven fabric does not significantly impair the occurrence of wrinkles or the anisotropy of sliding durability described below. By using the same type of fiber as fiber B used in the composite yarn as the weft or warp yarn perpendicular to the composite yarn, it is possible to suppress the occurrence of wrinkles due to the difference in thermal shrinkage between the warp and weft yarns, and to reduce the anisotropy of sliding durability due to the difference in yarn strength.

The mass ratio α of fluororesin fiber A in the composite yarn is 5 to 70%. By setting the mass ratio α of fluororesin fiber A in the composite yarn to this value, an optimal balance can be achieved between low friction, the transfer of fluororesin wear powder to fiber B, and the strength of fiber B as an aggregate. 25 to 60% is more preferable, and 40 to 55% is particularly preferable in terms of the balance between strength and sliding properties. If the mass ratio α of fluororesin fiber A in the composite yarn is less than 5%, low friction is significantly impaired. If it is greater than 70%, breakage of the fluororesin fiber and emission of fluororesin wear powder become significant, making it impossible to achieve the desired durability.

The means for obtaining a composite yarn from fluororesin fiber A and fiber B is not particularly limited, and can be selected from methods such as plying, blending, and blended spinning. Using plying and blending allows filament yarns to be selected for fluororesin fiber A and fiber B, which is preferable because it increases the strength of the composite yarn. Using blending allows the fluororesin fiber A single yarn and fiber B single yarn that make up the composite yarn to be more uniformly combined, resulting in a composite yarn that is uniform in the cross-sectional direction. Using plying and twisting allows a composite yarn to be obtained without entanglement, resulting in a composite yarn that is uniform in the longitudinal direction.

When a composite yarn is obtained by plying and twisting fluororesin fiber A and fiber B, the number of twists during plying and twisting is preferably such that the twist factor k is 1,000 or more and 25,000 or less. Here, the twist factor k is calculated by the following formula, where T [t/m] is the number of twists per meter and D [dtex] is the fineness of the composite yarn.
k = T × D ^0.5
More preferably, it is 1,000 or more and 10,000 or less, and particularly preferably 2,000 or more and 7,000 or less.

When a composite yarn is obtained by plying and twisting fluororesin fiber A and fiber B, it is preferable that fiber B be twisted before plying and twisting. Twisting can suppress the opening of fiber B due to abrasion during weaving, preventing the phenomenon in which the opened fiber B covers the fluororesin fiber A in the composite yarn, impairing low friction. In this case, the twist coefficient of fiber B before plying and twisting is preferably 500 to 5,000. Furthermore, if it is 500 to 3,000, in addition to the above effects, the twisting improves the strength of fiber B, and when woven, fiber B exists more firmly as a skeletal fiber, improving sliding durability. A twist coefficient of 900 to 3,000 is particularly preferable. If the twist coefficient of fiber B is greater than 5,000, the strength may be lower than before twisting. When twisting fiber B, a process of simply twisting raw yarn of the desired fineness may be used, or a process of twisting together yarns of a fineness smaller than the desired fineness may be used. For example, when preparing fiber B having a twist number of 33 [t/m] and a fineness of 850 [dtex], a raw yarn of fiber B having a fineness of 850 [dtex] may be twisted at 33 [t/m], or two raw yarns of fiber B having a fineness of 425 [dtex] may be ply-twisted at 33 [t/m].

In the woven fabric of the present invention, the ratio X/Y, where X is the area ratio of fluororesin fiber A on the woven fabric surface and Y is the mass ratio of fluororesin fiber A in the woven fabric, is from 1 to 5. The area ratio of fluororesin fiber A on the woven fabric surface referred to here means the proportion of the area _SA of fluororesin fiber A to the photographed area S _tot when the surface of the fabric is photographed with a microscope, and is calculated by the following formula:

Area ratio X of fluororesin fiber A = S _A / S _tot × 100 [%]
X/Y represents the degree to which the fluororesin fibers A present in the woven fabric are distributed on the surface of the woven fabric, and the larger the X/Y, the more concentrated the fluororesin fibers are present on the surface of the woven fabric. To achieve excellent wear durability, it is important to strike a balance between low friction at the initial stage of sliding and low friction as the woven fabric wears due to sliding. X/Y is preferably 1 to 2, and even more preferably 1.2 to 1.65. A ratio of 1.2 to 1.6 is particularly preferable, as it can provide particularly excellent wear durability while maintaining initial sliding properties. When X/Y is less than 1, the amount of fluororesin fibers A present on the surface of the woven fabric is reduced relative to the mass ratio of fluororesin fibers A in the woven fabric. Therefore, when subjected to high-speed sliding under a high load, the frictional resistance relative to the fabric strength is relatively high at the initial stage of sliding, which makes it prone to early breakage initiation and results in insufficient wear durability. The larger the X/Y ratio, the more the amount of fluororesin fiber A present on the surface of the woven fabric relative to the mass ratio of fluororesin fiber A in the woven fabric. When X/Y is greater than 5, the amount of fluororesin fiber A present on the surface of the woven fabric becomes excessively large. Therefore, when exposed to high-speed sliding under a high load, although the frictional resistance can be reduced in the early stages of sliding, the fluororesin fiber wear generates fluorine wear dust, which is expelled early and the fluororesin fiber remaining in the woven fabric is depleted. As a result, the frictional resistance becomes relatively high compared to the fabric strength in the middle to late stages of sliding, and sufficient wear resistance cannot be obtained.

The area ratio X of fluororesin fiber A on the woven fabric surface is preferably 10% or more and 60% or less. If the area ratio X of fluororesin fiber A on the woven fabric surface is 10% or more, frictional resistance at the initial stage of sliding can be reduced to a certain extent, and wear resistance can be ensured. If the area ratio X of fluororesin fiber A on the woven fabric surface is 60% or less, fibers other than fluororesin fiber can be present to a certain extent as skeletal fibers in the woven fabric, and wear resistance can be ensured. From the perspective of reducing frictional resistance at the initial stage of sliding and skeletal fiber arrangement in the fabric, a more preferable condition is 20% or more and 55% or less, and a particularly preferable condition is 40% or more and 55% or less.

The mass ratio Y of the fluororesin fibers in the woven fabric is preferably 5% or more and 55% or less. It is more preferably 15% or more and 55% or less, and a particularly preferred condition is 25% or more and 45% or less.

To ensure that X/Y falls within the above range, it is preferable to arrange more fluororesin fibers on the surface of the woven fabric. In other words, to achieve X/Y within the above range, when making the composite yarn, more fluororesin fibers can be arranged near the surface of the composite yarn, or the weave structure can be controlled so that more fluororesin fibers are exposed on the surface of the woven fabric.

In the present invention, the means for obtaining a composite yarn is not particularly limited. However, in order to arrange a large amount of fluororesin fiber near the surface layer of the composite yarn when it is produced, it is relatively easy to employ a ply-and-twist process and control the ply-and-twist conditions. Specifically, methods that can be employed include covering fiber B with fluororesin fiber A, plying a ply-and-twist yarn of fiber B and fluororesin fiber A with fluororesin fiber A again, and applying high tension to fiber B during ply-and-twist to arrange fluororesin fiber A in the sheath side of the composite yarn. When a composite yarn is obtained by plying and twisting fluororesin fiber A and fiber B without using the special methods listed above, the volume ratio and area ratio of fluororesin fiber A in the composite yarn are approximately equal. Increasing the area ratio of fluororesin fiber in the composite yarn also increases the mass ratio Y of fluororesin fiber A in the woven fabric. Therefore, other means, such as controlling the weave structure, are typically used to control X/Y within the range of 1 to 5.

In the present invention, the weave is not particularly limited, but methods for controlling the weave to expose more of the fluororesin fiber on the surface of the fabric include using a 3/1 twill weave, a 2/1 twill weave, a satin weave, etc., and varying the ratio of exposed warp and weft threads on the surface. By arranging yarns containing more fluororesin fiber A in the warp or weft thread that is more exposed on the surface, it is possible to control X/Y to a range of 1 or more and 5 or less. However, in 2/2 twill weaves and simple plain weaves, the warp and weft threads are exposed to the same extent on the surface, making it difficult to expose more of the fluororesin fiber on the surface of the fabric when using ordinary composite yarns.

In the present invention, the fluororesin that is a component of the fluororesin fiber may be one composed of monomer units containing one or more fluorine atoms in the main chain or side chain. Among these, those composed of monomer units with a large number of fluorine atoms are preferred.

The above-mentioned monomer units containing one or more fluorine atoms preferably account for 70 mol% or more of the repeating structural units of the polymer, more preferably 90 mol% or more, and even more preferably 95 mol% or more.

Examples of monomers containing one or more fluorine atoms include fluorine atom-containing vinyl monomers such as tetrafluoroethylene, hexafluoropropylene, and chlorotrifluoroethylene, and of these, it is preferable to use at least tetrafluoroethylene.

Examples of fluororesins that can be used include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-p-fluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer (ETFE), etc., either alone or in blends of two or more types.

In fluororesins containing tetrafluoroethylene units, a higher content of tetrafluoroethylene units is preferable in terms of sliding properties, and copolymers in which 90 mol% or more, preferably 95 mol% or more of the total is tetrafluoroethylene are preferred, and it is most preferable to use polytetrafluoroethylene fibers as a homopolymer of tetrafluoroethylene.

The fluororesin fiber A used in the present invention can be in the form of either a monofilament consisting of a single filament or a multifilament consisting of multiple filaments, but from the standpoint of weaving ability and surface irregularities when made into a fabric, multifilament is preferred.

The total fineness of the fluororesin fiber A used in the present invention is preferably within the range of 50 to 6,000 dtex. It is more preferably within the range of 500 to 5,500 dtex, and even more preferably within the range of 400 to 1,500 dtex. If the total fineness of the fibers constituting the fabric is 50 dtex or more, a certain level of fiber strength can be ensured, and thread breakage during weaving can be reduced, improving processability. If it is 6,000 dtex or less, good processability during weaving can be achieved.

As the fiber B, organic fibers such as cotton, polyester fiber, polyamide fiber, polyparaphenylene terephthalamide (para-aramid) fiber, polymetaphenylene isophthalamide (meta-aramid) fiber, polyphenylene sulfide (PPS) fiber, polyparaphenylene benzobisoxazole (PBO) fiber, ultra-high molecular weight polyethylene (UHMWPE) fiber, and liquid crystal polyester fiber, as well as inorganic fibers such as glass fiber, carbon fiber, and silicon carbide fiber can be used, but from the standpoint of processability, organic fibers are preferred.

From the perspective of improving the abrasion resistance of the woven fabric, it is preferable that fiber B has a tensile strength of 7 cN/dtex or more. The tensile strength of fiber B is more preferably 15 to 50 cN/dtex, and even more preferably 18 to 50 cN/dtex. This further reduces fiber breakage even when subjected to high-speed sliding under high load, and helps form a self-lubricating film as the fluororesin fiber wears.

From the perspective of durability in environments where frictional heat is generated due to sliding, it is preferable that fiber B has a heat resistance temperature of 280°C or higher. Heat resistance temperature here means that the melting point, softening point, or decomposition point is at or above that temperature. If fiber B has two or more of the melting point, softening point, and decomposition point, the lower temperature is used. It is more preferable that the heat resistance temperature of the above fiber is 300°C or higher. Furthermore, by using a fiber with no melting point, softening due to frictional heat can be suppressed, resulting in excellent wear resistance.

From the perspective of dimensional stability of the woven fabric, it is preferable that fiber B has a tensile modulus of 20 to 800 cN/dtex. Furthermore, if fiber B has a tensile modulus of 450 to 800 cN/dtex, the fabric structure can be maintained even when subjected to high-speed sliding under high load, resulting in particularly excellent abrasion resistance. If fiber B has a tensile modulus of 20 cN/dtex or more, the dimensional stability of the fabric is improved, resulting in a fabric with excellent abrasion resistance. If the tensile modulus is 800 cN/dtex or less, the rigidity of the fiber is not too high, and weaving properties are not impaired even when interwoven with low-rigidity fluororesin fibers, which is preferable. The elongation of fiber B is preferably 1 to 15%, and more preferably 1 to 5%. Among these, a value of 1 to 3% is particularly preferable because it can reduce dimensional change in the fabric when frictional force is applied. If fiber B has an elongation of 1% or more, thread breakage during weaving is reduced, improving processability. If the thickness is within the range of 1 to 15%, the dimensional stability of the fabric is improved, and the fabric can be used in areas where dimensional accuracy is required as a sliding fabric.

In view of the above, it is particularly preferred that fiber B is a fiber selected from liquid crystal polyester fiber, para-aramid fiber, and polyparaphenylene benzobisoxazole fiber.

The form of fiber B is not particularly limited, and either filament (long fiber) or spun (spun yarn) may be used, but filament is preferred from the standpoint of tensile strength and tensile rigidity. Furthermore, either a monofilament consisting of a single filament or a multifilament consisting of multiple filaments can be used, but multifilaments are particularly preferred because they have a large surface area, making it easier for fluorine abrasion powder generated by abrasion of fluororesin fiber A to be transferred to fiber B.

The total fineness of fiber B is preferably within the range of 200 to 4000 dtex. A range of 4000 to 4000 dtex is more preferable, and even more preferably within the range of 800 to 2000 dtex. If the total fineness of the fibers making up the fabric is 200 dtex or more, the fibers are strong, preventing fiber breakage during abrasion and reducing thread breakage during weaving, improving processability. If the total fineness is 4000 dtex or less, the unevenness of the fabric surface is small, minimizing the impact on low friction properties.

To further enhance the abrasion resistance of the woven fabric obtained as described above, the fabric can be impregnated with a resin. The resin used for the impregnation can be a thermosetting or thermoplastic resin. Thermosetting resins include, but are not limited to, phenolic resin, melamine resin, urea resin, unsaturated polyester resin, epoxy resin, polyurethane resin, diallyl phthalate resin, silicone resin, polyimide resin, vinyl ester resin, and modified resins thereof. Thermoplastic resins include vinyl chloride resin, polystyrene resin, ABS resin, polyethylene resin, polypropylene resin, fluororesin, polyamide resin, polyacetal resin, polycarbonate resin, and polyester resin. Synthetic rubbers or elastomers such as thermoplastic polyurethane, butadiene rubber, nitrile rubber, neoprene, and polyester elastomers are also preferred. Resins primarily composed of phenolic resin and polyvinyl butyral resin, unsaturated polyester resin, vinyl ester resin, polyethylene, polypropylene, and other polyolefin resins, as well as polyester resins, are preferred due to their impact resistance, dimensional stability, strength, and cost. These thermosetting and thermoplastic resins may contain various additives that are commonly used industrially for their purposes, applications, and to improve productivity or properties in the manufacturing and processing steps. For example, modifiers, plasticizers, fillers, release agents, colorants, diluents, etc. The term "major component" as used herein refers to the component with the largest mass ratio among the components excluding the solvent. In the case of a resin whose main components are a phenolic resin and a polyvinyl butyral resin, this means that the mass ratios of these two resins are first and second (in no particular order).

When using a thermosetting resin, the most common method for impregnating the fabric with resin is to dissolve the thermosetting resin in a solvent to prepare a varnish, and then impregnate and coat the fabric with the varnish using processes such as knife coating, roll coating, comma coating, and gravure coating. When using a thermoplastic resin, melt extrusion lamination is commonly used.

If necessary, a lubricant or the like can be added to the woven fabric of the present invention. There are no particular restrictions on the type of lubricant, but silicone-based lubricants or fluorine-based lubricants are preferred.

The woven fabric of the present invention thus obtained is a ply-twisted fabric with an optimized composition of fluororesin fiber A and non-fluororesin fiber B. Therefore, even when subjected to high-speed sliding under high loads, it suppresses the emission of fluorine wear particles. Furthermore, fiber B functions as a skeletal fiber supporting fluororesin fiber A, resulting in long-term sliding durability. Therefore, the woven fabric of the present invention exhibits high sliding durability in applications that have traditionally been difficult to use for long periods due to high-speed sliding under high loads, achieving extremely high industrial practicality. Therefore, it exhibits high durability in applications requiring sliding properties, such as sliding fabrics. It is particularly preferred for use in cable covers for robot arms. Robot arm cable covers using at least a portion of the woven fabric of the present invention have low friction and fabric strength, resulting in a long product life, even in usage environments where they rub against parts of equipment at high speeds under high loads.

Below, examples of the present invention are described along with comparative examples.

The measurement methods for various properties used in this example are as follows:

(1) Fineness The fabric was disassembled, and the fineness of the disassembled yarn was measured in accordance with JIS L1013:2010 "Testing Methods for Chemical Fiber Filament Yarns" 8.3.B Method (simplified method). However, if the amount of disassembled yarn required for the above measurement method cannot be secured, the results of the test using the maximum length and number of trials that can be secured shall be used instead.

(2) Tensile strength of fiber The fabric was disassembled, and the breaking strength of the disassembled yarn was measured in accordance with 8.5 of JIS L1013:2010 "Testing method for chemical fiber filament yarn." However, if the amount of disassembled yarn required for the above measurement method cannot be secured, the results of the test using the maximum length and number of trials that can be secured shall be used instead.

(3) Fiber elongation The woven fabric was disassembled, and the elongation (elongation rate) of the disassembled yarn was measured in accordance with 8.5 of JIS L1013:2010 "Testing method for chemical fiber filament yarn." However, if the amount of disassembled yarn required for the above measurement method cannot be secured, the results of the test using the maximum length and number of trials that can be secured shall be used instead.

(4) Tensile modulus: In the measurement of (3), it was calculated from the modulus at an elongation of 0.5% (average slope from an elongation of 0.45% to an elongation of 0.55%).

(5) Mass ratio α of fluororesin fiber A in the composite yarn
The woven fabric was cut into a 200 mm warp x 200 mm weft, and then the warp and weft yarns were separated to obtain separated yarns. Five composite yarns were randomly selected from the obtained separated yarns for each of the warp separated yarns and weft separated yarns, and the composite yarns were separated into fluororesin fiber A and other fibers, and the masses of each were measured. The total mass of the five composite yarns was W, and the total mass of the fluororesin fiber A in the five composite yarns was _WF , and the mass ratio α of the fluororesin fiber A in the composite yarn was calculated using the following formula:
α=W _F /W×100 [%]
However, if the amount of yarn required for the above measurement method cannot be secured for the disassembled yarn, the results of the test using the maximum length and number of trials that can be secured shall be used instead.

(6) Weave Density In accordance with 8.6.1 of JIS L1096:2010 "Testing Methods for Woven and Knit Fabrics," the sample was placed on a flat table, and unnatural wrinkles and tension were removed. The number of warp threads and weft threads contained within 50 mm intervals at different points was counted, and the average value for each was calculated for each unit length.

(7) Area ratio X of fluororesin fiber A on the surface of the fabric
The fabric was photographed at 50x magnification using a Keyence microscope "VHX-2000," the photographed area was designated S _tot , the area occupied by fluororesin fiber A was designated S _A , and the area ratio of fluororesin fiber A was calculated using the following formula: However, when X differs between the front and back surfaces, the larger value of X is used as the representative value.
Area ratio X of fluororesin fiber A = S _A / S _tot × 100 [%]
The photographed area S _tot and the area S _A occupied by the fluororesin fiber A were calculated using image analysis software "WinR00F2015" manufactured by Mitani Corporation.

(8) Mass ratio Y of fluororesin fiber A in the woven fabric
After cutting the woven fabric into a length of 200 mm x width of 200 mm, the warp and weft yarns were disassembled and the total mass W of the disassembled yarns was measured. Next, only the composite yarns were selected from the disassembled yarns, and the total mass _W1 of the composite yarns in the woven fabric was measured. Next, the fluororesin fiber that was present alone in the woven fabric, rather than the composite yarns, was selected and its total mass _W2 was measured. The mass ratio Y of the fluororesin fiber A in the woven fabric was calculated using the following formula.
Y=(W ₁ ×α/100+W ₂ )/W×100 [%]
However, if the amount of yarn required for the above measurement method cannot be secured for the disassembled yarn, the results of the test using the maximum length and number of trials that can be secured shall be used instead.

(9) Number of twists The woven fabric was disassembled, and the number of twists of the disassembled yarn was measured in accordance with 8.13.1 of JIS L1013:2010 "Testing methods for chemical fiber filament yarns."
However, if the amount of yarn required for the above measurement method cannot be secured for the disassembled yarn, the results of testing using the maximum length and number of trials that can be secured may be used instead.

(10) Dynamic friction coefficient: Measured by the ring wear test shown below.

In accordance with Method A of JIS K7218:1986 "Sliding abrasion test method for plastics," the fabric was sampled to a length of 30 mm and a width of 30 mm, placed on a stainless steel plate of the same size and approximately 3 mm thick, and fixed in a sample holder.

The mating material was a hollow cylindrical ring made of S45C with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a length of 15 mm. The surface of the ring was polished with a sandpaper to adjust the surface roughness to Ra = 0.8 μm ± 0.1. A roughness measuring instrument (Mitutoyo "SJ-201") was used to measure the roughness.

The ring wear tester used was an A&D Model EFM-III-EN. Tests were conducted at a friction load of 20 MPa and a friction speed of 400 mm/s, the sliding torque was measured, and the average friction coefficient up to break was calculated. Since the static friction coefficient is included immediately after the start of sliding, the average friction coefficient from 1 second after the start of sliding (sliding distance 0.4 m) to break was calculated as the dynamic friction coefficient.

Those with a dynamic friction coefficient of less than 0.055 were rated A, those with a coefficient of dynamic friction of 0.055 or more and 0.060 or less were rated B, those with a coefficient of dynamic friction of 0.060 or more and 0.065 or less were rated C, and those with a coefficient of dynamic friction of more than 0.065 were rated D.

(11) Sliding durability distance In the above ring abrasion test, sliding was continued until the fabric broke, and those that did not break even after sliding for 60 m were rated as A, those that broke after sliding for 50 m or more but less than 60 m were rated as B, those that broke after sliding for 40 m or more but less than 50 m were rated as C, those that broke after sliding for 25 m or more but less than 40 m were rated as D, and those that broke after sliding for less than 25 m were rated as E.

Example 1
A composite yarn was obtained by plying and twisting a PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) having a total fineness of 880 dtex, a single yarn count of 120 filaments, and a twist count of 33 t/m with a liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) having a total fineness of 850 dtex, a single yarn count of 144 filaments, and a twist count of 33 t/m at a twist count of 167 t/m. Then, a 3/1 twill fabric was produced on a loom using the ply and twisted yarn as the warp and a liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) having a total fineness of 1700 dtex and a single yarn count of 288 filaments. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 2
A woven fabric was obtained in the same manner as in Example 1, except that the composite yarn used in Example 1 was used as the warp and weft.

Comparative Example 1
A woven fabric was obtained in the same manner as in Example 1, except that PTFE fiber ("Toyoflon" (registered trademark), manufactured by Toray Industries, Inc.) having a total fineness of 1760 dtex and a single filament count of 240 was used for the weft.

Example 3
A liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 425 dtex and a single filament count of 72 filaments was plied with a PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 880 dtex and a single filament count of 120 filaments. The plied yarn was then plied with a liquid crystal polyester fiber with a total fineness of 425 dtex and a single filament count of 72 filaments at a twist rate of 167 t/m to obtain a plied yarn. A 3/1 twill fabric was produced on a loom using the plied yarn as the warp and liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1700 dtex and a single filament count of 288 filaments as the weft. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 4
A liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 850 dtex and a single filament count of 144 filaments was plied with a PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 440 dtex and a single filament count of 60 filaments. The plied yarn was then plied with a PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 440 dtex and a single filament count of 60 filaments at a twist rate of 167 t/m to obtain a plied yarn. A 3/1 twill fabric was produced on a loom using the plied yarn as the warp and a liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1700 dtex and a single filament count of 288 filaments as the weft. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 5
A woven fabric was obtained in the same manner as in Example 1, except that the number of twists of fiber B before plying and twisting was 0 t/m.

Example 6
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 440 dtex, a single yarn count of 60 filaments, and a twist count of 33 t/m was combined with a liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1275 dtex, a single yarn count of 216 filaments, and a twist count of 33 t/m to obtain a combined and twisted yarn at a twist count of 167 t/m. Then, a 3/1 twill fabric was produced on a loom using the combined and twisted yarn as the warp and a liquid crystal polyester fiber ("Scivelas" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1700 dtex and a single yarn count of 288 filaments. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 7
A woven fabric was obtained in the same manner as in Example 6, except that the composite yarn used in Example 6 was used as the warp and weft.

Comparative Example 2
A woven fabric was obtained in the same manner as in Example 6, except that the warp yarns used in Example 6 were used as the weft yarns, and the weft yarns used in Example 6 were used as the warp yarns.

Example 8
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 880 dtex, a single filament count of 120 filaments, and a twist count of 33 t/m was combined with a polyparaphenylene terephthalamide fiber ("Kevlar" (registered trademark) manufactured by DuPont-Toray Co., Ltd.) with a total fineness of 850 dtex, a single filament count of 144 filaments, and a twist count of 33 t/m to obtain a doubled-twisted yarn at a twist count of 167 t/m. A 3/1 twill fabric was then produced on a loom using the doubled-twisted yarn as the warp and polyparaphenylene terephthalamide fiber ("Kevlar" (registered trademark) manufactured by DuPont-Toray Co., Ltd.) with a total fineness of 1700 dtex and a single filament count of 288 filaments as the weft. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 9
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 880 dtex, a single yarn count of 120 filaments, and a twist count of 33 t/m was combined with a polyester fiber ("Tetoron" polyethylene terephthalate fiber manufactured by Toray Industries, Inc.) with a total fineness of 850 dtex, a single yarn count of 144 filaments, and a twist count of 33 t/m at a twist count of 167 t/m to obtain a doubled-twisted yarn. A 3/1 twill fabric was then produced on a loom using the doubled-twisted yarn as the warp and polyester fiber ("Tetoron" polyethylene terephthalate fiber manufactured by Toray Industries, Inc.) with a total fineness of 1700 dtex and a single yarn count of 288 filaments as the weft. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Example 10
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 880 dtex, a single yarn count of 120 filaments, and a twist count of 33 t/m was combined with a polyphenylene sulfide fiber ("Torcon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 850 dtex, a single yarn count of 144 filaments, and a twist count of 33 t/m at a twist count of 167 t/m to obtain a combined and twisted yarn. Then, a 3/1 twill fabric was produced on a loom using the combined and twisted yarn as the warp and polyphenylene sulfide fiber ("Torcon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1700 dtex and a single yarn count of 288 filaments as the weft. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

Comparative Example 3
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 440 dtex, single yarn count of 60 filaments, and twist count of 33 t/m was combined with a polyester fiber ("Tetoron" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 44 dtex and single yarn count of 18 filaments, a polyethylene terephthalate fiber, at a twist count of 210 t/m, to obtain a doubled-twisted yarn. Then, a five-ply satin fabric was produced on a loom using the doubled-twisted yarn as the warp and a polyester fiber ("Tetoron" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 26 s/2 (454 dtex) as the weft. The fabric was then scouring-tested in a scouring tank at 80°C and heat-set at 180°C.

Comparative Example 4
A PTFE fiber ("Toyoflon" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 2660 dtex, single yarn count of 360 filaments, and twist count of 33 t/m was ply-twisted with a carbon fiber ("Torayca" (registered trademark) manufactured by Toray Industries, Inc.) with a total fineness of 1980 dtex, single yarn count of 3000 filaments, and twist count of 33 t/m at a twist count of 167 t/m to obtain a ply-twisted yarn. Then, using this ply-twisted yarn as the warp and weft, a 2/2 twill fabric was produced on a loom. The fabric was then scoured in a scouring tank at 80°C and heat-set at 180°C.

The evaluation results for the composite yarn composition, fabric composition, dynamic friction coefficient, and sliding durability distance for the fabrics described in the examples and comparative examples are summarized in Tables 1 and 2.

Claims (13)

A woven fabric using a composite yarn of fluororesin fiber A and fiber B other than fluororesin fiber as at least one of the warp and weft yarns, wherein the mass ratio α of fluororesin fiber A in the composite yarn is 5 to 60%, and the ratio X/Y of the area ratio X of fluororesin fiber on the surface of the woven fabric to the mass ratio Y of fluororesin fiber in the woven fabric is 1 or more and 1.65 or less. 2. The woven fabric according to claim 1, wherein a composite yarn is used as either the warp or weft yarn, and fiber B is used as either the weft or warp yarn perpendicular to the composite yarn. The woven fabric according to claim 1 or 2, wherein the area ratio X is 10% or more and 60% or less. The woven fabric according to any one of claims 1 to 3, wherein the composite yarn is a plied yarn obtained by plying together fluororesin fiber A and fiber B other than fluororesin fiber. The woven fabric according to claim 4, wherein fiber B constituting the ply-twisted yarn is a twisted yarn. The woven fabric according to any one of claims 1 to 5, wherein the fluororesin fiber A is made of polytetrafluoroethylene resin. A woven fabric according to any one of claims 1 to 6, wherein fiber B has a tensile strength of 7 cN/dtex or more. The woven fabric described in claim 7, wherein fiber B has a tensile strength of 15 to 50 cN/dtex. A woven fabric according to any one of claims 1 to 8, wherein fiber B has a heat resistance temperature of 280°C or higher. A woven fabric according to any one of claims 1 to 9, wherein fiber B has a tensile modulus of elasticity of 450 to 800 cN/dtex. The woven fabric according to any one of claims 1 to 10, wherein fiber B is an organic fiber. The woven fabric according to any one of claims 1 to 11, wherein fiber B is a fiber selected from liquid crystal polyester fiber, para-aramid fiber, and polyparaphenylene benzobisoxazole fiber. A cable cover for a robot arm, at least in part made from the woven fabric described in any one of claims 1 to 12.