JPH0252931B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for adhering aromatic polyamide fibers and rubber compounds, and more specifically, the bending stability and adhesion of aromatic polyamide fibers in a composite of aromatic polyamide fibers and rubber compounds. The present invention also relates to a method of adhering aromatic polyamide fibers and a rubber compound, which have excellent binding properties of fiber filaments. (Prior Art) Generally, industrial rubber products such as rubber hoses, power transmission belts, conveyor belts, and tires are reinforced using fiber materials for rubber reinforcement. In order to improve performance, aromatic polyamide fibers (for example, Kevlar, trade name), which have better physical properties than polyamide fibers, polyester fibers, etc., have come to be widely used. However, this type of aromatic polyamide fiber,
It is a high-strength, high-modulus organic fiber that has good thermal stability, strength and modulus retention under high temperature and high humidity, and excellent dimensional stability under heat and humidity. It has the drawbacks of poor adhesion with compounds and poor bending fatigue stability when made into a composite. In particular, in cut edge type V-belts, V-ribbed belts, and toothed belts in which the cut surfaces of the fiber cords are exposed, there is a problem in that the fiber filaments jump out from the cut surfaces (hereinafter referred to as fraying). Therefore, in order to improve these issues,
Various methods have been studied from different perspectives. That is, conventional methods for such improvement include a method of treating with a resorcinol-formalin-rubber latex adhesive liquid (hereinafter referred to as RFL liquid), a method of pre-treating with an epoxy or isocyanate compound, and then treating with an RFL liquid, etc. However, the former method has good bending fatigue stability but poor adhesion, while the latter method has good adhesion but the treated fibers become stiff and the bending fatigue stability is poor. However, none of these have yet been fully satisfied. The inventors of the present invention have long dealt with the above-mentioned circumstances and endeavored to improve them, and first pretreated aromatic polyamide fibers with a mixed solution of an epoxy compound having at least one epoxy group and liquid rubber. We proposed an adhesion method in which the material is treated with RFL liquid and then vulcanized in close contact with unvulcanized rubber. Although this method significantly improved the bending fatigue stability and fraying compared to the conventional method, there was still a problem that the adhesiveness was somewhat inferior, and there remained room for further investigation. (Problems to be Solved by the Invention) The present invention not only improves these problems, but also improves the bending fatigue stability and fraying of a composite made of aromatic polyamide fibers and a rubber composition. The purpose is to improve the adhesive strength between the two. (Means for solving the invention) That is, the present invention has two characteristics:
One method involves soaking pre-twisted or aligned aromatic polyamide fibers in rubber glue or a resorcinol-formalin-latex solution and drying them, and then collecting and twisting a plurality of aromatic polyamide fibers that have undergone the above treatment. The other method is to bond the aromatic polyamide fibers and the rubber compound by vulcanizing the aromatic polyamide fibers in close contact with the unvulcanized rubber. Rubber glue or resorcinol - formalin -
After being dipped in a latex solution and dried, a plurality of the above-treated aromatic polyamide fibers are collected and twisted, further dipped in the above-mentioned rubber glue or resorcinol-formalin-latex solution and dried, and then unvulcanized. A method of adhering aromatic polyamide fibers and rubber compounds by vulcanizing them in close contact with rubber. That is, in the bonding method of the present invention, aromatic polyamide fibers are adhesive-treated in advance, several fiber cords are collected and twisted, and the surface of the obtained fiber cord is evenly coated with adhesive. It is possible to increase the binding force between the cords and to prevent fibrillation of the filaments. If the cords thus obtained are further subjected to adhesive treatment, the binding force between the cords will further increase, and the object of the present invention can be further enhanced. The aromatic polyamide fiber used in the present invention refers to one in which the fibrous material is poly p- or m-benzamide, poly-p-phenylene terephthalamide, or poly-m-phenylene isophthalamide fiber, and Rubber compounds used as adherends include SBR, EPT, IIR, CR, NR, etc. alone or blends thereof, among which CR compounds alone or blends with these are the most preferred compounds. It is. Further, the rubber glue used in the present invention is SBR,
It is a mixture of EPT, IIR, CR, NR, etc., dissolved in a solvent, and an adhesion promoter such as an isocyanate compound or an epoxy compound may be added to the rubber glue. Next, the fibers were immersed in this rubber glue for 0.1 to 0.5 minutes, and
Heat treatment at 200℃. When a resorcinol-formalin-rubber latex mixture (RFL liquid) is used instead of the rubber paste, the fibers are immersed in this RFL liquid for 0.1 to 0.5 minutes and heat treated at 150°C to 230°C. The RFL liquid used here preferably has a molar ratio of resorcin to formalin of 1:0.5 to 3 from the viewpoint of adhesive strength. The rubber latex is usually a synthetic rubber latex, and the synthetic rubber latex includes chloroprene rubber latex and styrene-butadiene-vinylpyridine rubber latex, which may be used alone or in combination. The adhesive-treated fibers have superior adhesive strength, bending resistance, and fiber filament binding properties compared to conventional methods, and can be used for power transmission belts, conveyor belts,
It can be applied to products such as toothed belts and tires. Hereinafter, embodiments of the method of the present invention will be explained more specifically and in detail with reference to Examples. (Example) Example 1 A cord of aromatic polyamide fiber (using Dupont's Kevlar product name) with a composition of 1500D/1 and pre-twisted 11 times/10cm was coated with rubber glue having the composition shown in Table 1. Or after soaking in RFL treatment solution,
Heat treated at 150℃ for 2 minutes, then treated
Collect 4 cords of 1500D/1 configuration, 11 times/10cm
(Example No. 1, No. 3). Further, the twisted cord was immersed in a treatment solution having the same composition as shown in Table 1, and then heat treated at 150° C. for 2 minutes (Example No. 2, No. 4). These treated cords were then spun onto adhesive tape spread on a drum and a 3 mm thick chloroprene rubber compound from Table 3 was laminated thereon. Then, this laminated sample was cut and vulcanized at 150°C for 30 minutes. After vulcanization, the sample was cut into a width of 25 mm and tested at a tensile rate using a peel tester (Shimadzu: Autograph). Peel adhesion was measured at 50 mm. The results are also listed in Table 1. In addition, in the table, comparative example No. 2 is
This is a case where an aromatic polyamide fiber cord having a 1500D/1×4 structure was treated only with RFL liquid (Table 2). Example 2 Each cord treated in Example 1 was spun onto a 1.0 mm thick chloroprene rubber compound shown in Table 3, which was separately wound on a drum, and a chloroprene rubber compound of the same thickness and composition was placed on top of the chloroprene rubber compound of Table 3 above. Layering rubber compounds,
Steam vulcanization was carried out at 8 kg/cm ² for 30 minutes, and a sample in which two cords were embedded was prepared from the vulcanized product. Then, this sample was wrapped around a rotating bending bar located vertically, one end of the sample was fixed to a frame, a load of 2 kg was applied to the other end, and the rotating bending bar was reciprocated 5000 times to conduct a bending test. The strength of the sample was measured at a tensile speed of 50 mm/min. The results are also listed in Table 1 above. Example 3 The vulcanized product prepared in Example 2 was cut along the embedded cord with a knife just above the cord, and the cut surface of the cord was rubbed with a fingernail 10 times to determine the degree of fraying. visually inspected in 5 stages (A: none;
B: hard to fray, C: frays a little, D: frays easily, E: frays). These results are also shown in Table 1 above.

[Table] *2 Manufactured by Petrochemical Company

【table】

[Table] (Effects of the invention) As described above, the adhesive method of the present invention is superior to the conventional method in which several aromatic polyamide fibers are collected and twisted, and then adhesive treatment is performed. By collecting and twisting the adhesive-treated cords, the resulting cord has good cohesion, and it is also possible to suppress fibrillation of the filament and prevent it from fraying. In order to re-bond the cords, it is possible to apply the adhesive evenly around each component cord, which has an excellent effect of further improving the bending fatigue stability of the composite and the fraying of the fibers.

Claims (1)

[Scope of Claims] 1. After immersing first-twisted or aligned aromatic polyamide fibers in rubber glue or a resorcinol-formalin-latex solution and drying them, a plurality of aromatic polyamide fibers subjected to the above treatment are prepared. A method for adhering aromatic polyamide fibers and a rubber compound, which comprises gathering and twisting the fibers, and then vulcanizing the fibers in close contact with unvulcanized rubber. 2. After immersing the pre-twisted or aligned aromatic polyamide fibers in rubber glue or resorcinol-formalin-latex solution and drying, collect a plurality of the above-treated aromatic polyamide fibers and twist them. A method for adhering aromatic polyamide fibers and a rubber compound, characterized in that the fibers are further immersed in the rubber glue or resorcinol-formalin-latex solution, dried, and then vulcanized in close contact with unvulcanized rubber.