JPH0160569B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a liner cloth used for winding up unvulcanized rubber seals, and more specifically, it is a woven fabric made of a composite or mixed yarn of fibers made of a high-melting point polymer component and fibers made of a low-melting point polymer component. This invention relates to a liner cloth in which the intersection points of warp and weft yarns constituting the fabric are fused by melting of a low-melting polymer component, and the surface of the fabric is smooth. Rubber products such as tires and conveyor belts are made by laminating and gluing multiple sheets of unvulcanized rubber into sheets to achieve the desired thickness. By the way, unvulcanized rubber sheets are sticky, so for the purpose of preventing adhesion between sheets,
Conventionally, unvulcanized rubber sheets are generally wound into rolls by interposing woven fabrics such as natural fibers and synthetic fibers or polyolefin films for storage and transportation, and are rolled when used for processing rubber products. I put it back and use a rubber sheet. However, natural fibers such as silk and polyolefin films lack durability. Moreover, in the case of silk fabrics, when an unvulcanized rubber sheet is rolled into the fabric, a large amount of fuzz adheres to the surface of the rubber sheet, reducing the adhesiveness of the surface of the rubber sheet and causing problems in the processing of rubber products. This drawback is a phenomenon observed in synthetic fiber fabrics using spun yarn. In addition, polyolefin film liners tend to wrinkle over time, and the wrinkles are directly transferred to the surface of the rubber sheet.When processing rubber products by laminating unvulcanized rubber sheets, there are This has the disadvantage of entrapping air and increasing the number of defective products. Generally, the following properties are required for liner cloth for unvulcanized rubber sheets. (a) When only the rubber sheet is used from the liner cloth rolled up with the unvulcanized rubber sheet, it must be easy to separate from the unvulcanized rubber sheet. (b) Do not reduce the adhesion of the surface of the unvulcanized rubber sheet in contact with the liner cloth. (c) Wrinkles (particularly diameter wrinkles) are unlikely to occur during winding work, and winding workability is good. (d) It must be durable and inexpensive because it can be used repeatedly. (e) It should have little expansion and contraction and good dimensional stability. Among the above-mentioned required characteristics, a liner cloth that does not satisfy characteristics (a) and (b) is considered a fatal defect and cannot be used. In particular, in recent years, as tire production technology has improved, tires have become more radial, and highly activated substances have been blended into unvulcanized rubber to improve adhesion to tire reinforcing cords such as steel, which has also improved the adhesiveness of rubber sheets. The performance requirements for liner cloth are becoming stricter. Recently, durable synthetic fiber liners have begun to be used, but when using fabrics made of spun yarn, the adhesiveness of the unvulcanized rubber sheet surface decreases due to fluff adhesion similar to the silk fabric described above, and the texture of the fabric deteriorates. This causes air to be trapped in the uneven parts of the surface, causing a decrease in the adhesiveness of the rubber sheet. On the other hand, long fiber woven fabrics do not have the problem of reducing the adhesiveness of the rubber sheet due to fluff, but have the same drawback of reducing the adhesiveness of the rubber sheet from above the tissue. In other words, synthetic fiber fabrics satisfy mechanical properties, but
This means that there is a problem with the surface condition. For example, if a fabric made of spun yarn is used as a liner cloth, the liner should be treated with a chemical treatment that will not impede the adhesion of the rubber sheet even if it transfers to the rubber sheet surface, in order to improve the peelability from the rubber sheet. Cloth is sometimes used, but it lacks durability against repeated use. That is, a durable woven fabric with a surface shape in which the convex portions at the intersections of the threads constituting the woven fabric has a surface smoothness similar to that of a film can be said to be optimal. In addition, liner cloth is normally used repeatedly over a long period of time, and from the viewpoint of durability, it is necessary to be able to withstand winding, unwinding, and wear due to friction under specified tension conditions. In both cases, the tensile strength at break of the fabric before use is preferably 10 kg or more per cm, and synthetic fibers are superior if wear during use is taken into consideration. In view of these required physical properties, we have developed a liner cloth as a result of intensive research that has excellent durability, good peelability from unvulcanized rubber sheets, and does not reduce the adhesiveness of the rubber sheet surface. That is, the liner cloth for unvulcanized rubber sheets of the present invention is composed of at least two types of polymer components having a melting point difference of 30°C or more, and is woven with composite fibers in which the fiber cross-sectional circumference of the low perfect point polymer component is 40% or more. woven fabric, or a woven fabric woven from a blended yarn or mixed twisted yarn of the composite fiber and other synthetic fibers having a melting point higher than that of the low melting point polymer component by 30°C or more, and the woven fabric is It is heated and pressurized to a temperature higher than the melting temperature of the low melting point polymer component of the composite fibers that make up the woven fabric, so that part or all of the fibers that make up the woven fabric are fused, suppressing fluff and making the surface of the woven fabric smooth. This liner cloth for unvulcanized rubber is characterized by: The liner cloth of the present invention may be composed of a woven fabric made of a single yarn of the above-mentioned composite fibers, or may be composed of a blended yarn or mixed yarn of the above-mentioned composite fibers and other synthetic fibers. , in any case, a woven fabric containing composite fibers as described above,
For example, the composite fiber is passed through two heated rolls with a surface temperature that softens and melts the low melting point polymer component without affecting the high melting point polymer component of the composite fiber, applying an appropriate linear pressure, e.g., 0.1 to 1.0 kg/cm. By doing so, the low melting point polymer component on at least the surface of the woven fabric is softened and melted, the uneven structure on the woven fabric surface is flattened, and the fuzz of the fibers is suppressed to smooth the woven fabric surface. That is, a composite fiber having a low melting point polymer component as described above is used as a constituent fiber of a woven fabric, and the low melting point polymer component is used to flatten and smooth the surface of the woven fabric, and also to bond between the fibers,
The point is that it suppresses fuzz. In the present invention, the composite fiber must be made of at least two polymer components having different melting points. The difference in melting point between the two components should be at least 30°C. For example, as a high melting point polymer component,
Polyethylene terephthalate, polypropylene, etc. are suitable, and as the low melting point polymer component, polyethylene, saponified ethylene vinyl acetate copolymer, etc. are suitable. In addition to these combinations, a combination of a conventionally known fiber-forming homopolymer and a copolymer obtained by copolymerizing the polymer with another monomer to have a lower melting point than the homopolymer is of course applicable. Generally, liner cloth used for unvulcanized rubber sheets is used at temperatures ranging from room temperature to about 80°C, so it is preferable to make it from a fibrous material that has less heat shrinkage and thermal creep in that temperature range.
It is preferable that the thermal shrinkage or thermal creep under heating conditions of 80° C. for 1 hour is 5% or less. Further, as mentioned above, it is necessary that the tensile strength is 10 kg or more per 1 cm width. That is, if the shape of the liner cloth changes significantly under heating, wrinkles are likely to occur during repeated use, which will adversely affect the surface of the rubber sheet. The high melting point polymer component of the composite fiber must function as a strong support member for the liner cloth, and the other fibers used in combination with the composite fiber must also have the ability to function as strong support members. . In view of the above, other fibers to be used in combination with the composite fibers include, for example, in addition to the fibers of the polymer materials mentioned as the high melting point polymer component, polyvinyl alcohol fibers and the like are also effective. Of course, when blending fibers that function as other strong support members with the composite fibers, if the proportion of the low melting point polymer component in the entire woven fabric is too small, the desired effect of the present invention cannot be achieved. Composite fibers must account for at least 10% (wt) of the total amount including other fibers. The conjugate fiber used in the present invention is defined as one in which at least 40% of the circumference of the fiber in cross section is a low melting point polymer component. In other words, it is sufficient that at least 40% of the surface of the composite fiber is occupied by a low melting point polymer component, and the structure of the fiber does not matter. A core-sheath type is more preferable, in which a high-melting point polymer component serving as a strong supporting member is placed at the core, and a low-melting point polymer component surrounds this. The means for heating and smoothing the woven fabric was not specified, but the easiest method in practice is to pass it between a pair of pressure rollers heated to a predetermined temperature as described above. As mentioned above, a melting point difference of 30°C is sufficient between the high melting point polymer component and the low melting point polymer component of the composite fiber, and other fibers other than the composite fiber used as a strong support member also have a high melting point polymer component of the composite fiber. Same as low melting point polymer component and melting point difference is 30℃
It is enough. If the melting point difference is less than 30°C, the high melting point polymer component and the combined fibers will be adversely affected by heating and pressurization when smoothing the surface of the woven fabric, which will cause a decrease in the strength of the strong support member, which is undesirable. . As described above, in the present invention, some of the fibers constituting the liner cloth are made of a low melting point polymer component, and by softening and melting this after weaving, the fluff is suppressed by adhesion between the fibers, and the surface of the woven fabric is flattened and smoothed. This product eliminates the drawbacks of conventional liner cloths made of natural or synthetic fibers or liner sheets made of synthetic resin, and is of high practical value. Example 1 50% polyvinyl alcohol fiber and PE sheath,
A plain woven fabric was woven using a 20 count blended yarn with PET as the core and 50% by weight of composite fiber with PE and PET component ratio of 40:60. Both sides of the plain woven fabric were smoothed by passing it between two heated rollers prepared in advance and heated to a surface temperature of 150°C under a linear pressure of 0.2 kg/cm. When the resulting fabric, which is smooth on both sides, is rolled up as a liner cloth together with an SBR-based unvulcanized rubber sheet, the tackiness of the rubber sheet is as shown in Table 1 below. This was a marked improvement over the previous case. Moreover, the releasability from rubber was good. Example 2 Composite fiber 50 made of 50% polyester fiber, PE sheath, PP core, and the component ratio of PE and PP is 40:60.
A plain woven fabric was woven using a 20-count blended yarn blended at a weight ratio of %. A liner cloth was made by smoothing both sides under the same conditions as in Example 1, and after being rolled up together with an SBR unvulcanized rubber sheet, the tackiness of the rubber sheet surface was equal to that of the existing liner cloth. This was a marked improvement compared to the case. The peelability between the liner cloth and the rubber was also good. Example 3 A spun yarn made of 100% polyvinyl alcohol fiber (number 20) and 100% composite fiber made of PET (core), vinyl acetate, vinyl alcohol, copolymer (melting point 165°C) (sheath) Number of twists per 20th thread
A plain woven fabric was woven using alternately twisted and single-twisted cords with a twist direction S of 45 times/10cm. This is the surface temperature prepared in advance.
The fabric was passed between two heated rollers at 175°C under a linear pressure of 0.2 kg/cm to obtain a fabric with smoothness on both sides. After winding this up together with an SBR unvulcanized rubber sheet, the surface tackiness of the rubber sheet side was measured. As a result, the same effects as in Examples 1 and 2 were obtained. The above is summarized in Table 1.

[Table] (Note) ◎ Excellent, ○ Fair, △ Slightly inferior, ×
inferior

Claims (1)

[Claims] 1. Liner cloth for unvulcanized rubber has a melting point difference of 30
A woven fabric woven from composite fibers consisting of at least two types of polymer components having a temperature of 30°C or more, the fiber cross-sectional circumference of the low melting point polymer component being 40% or more, or the composite fiber and the low melting point polymer component therein. A woven fabric woven from a blended yarn or mixed yarn with other synthetic fibers having a high melting point of ℃ or higher, and the woven fabric is heated to a temperature higher than the melting temperature of the low-melting point polymer component of the composite fibers that make up the woven fabric. A liner cloth for unvulcanized rubber, characterized in that part or all of the fibers constituting the woven cloth are fused under pressure. 2. The liner cloth for unvulcanized rubber according to claim 1, wherein the woven fabric has a tensile strength at break of 10 kg or more per cm width, and the high melting point polymer component of the composite fibers is polyester or polypropylene. 3. The liner cloth for unvulcanized rubber according to claim 1, wherein the low melting point polymer component of the composite fibers is polyethylene, copolyester, nylon, or saponified ethylene-vinyl acetate copolymer. 4. The liner cloth for unvulcanized rubber according to claims 1 to 3, wherein the synthetic fibers to be blended or mixed and twisted with the composite fibers are polyvinyl alcohol fibers or polyester fibers.