JPH03211041A - Fiber reinforced rubber product - Google Patents

Abstract

PURPOSE:To improve drastically bend and fatigue resistance, by a method wherein a core thread is provided within a hollow part of a braided round rope having the hollow part braided cylindrically of an even number of yarn stripes of at least 4 pieces in a reinforcement body. CONSTITUTION:A reinforcement body 2 is constituted of a plurality of round braided ropes 7, 7,... having hollow part 8 braided cylindrically of an uneven number of yarn stripes 6, 6,... of at least 4 pieces and a core yarn 9 inserted and arranged within the hollow part 8 of the round braided ropes 7 each. An inorganic fiber, organic fiber and metallic fiber are used as a kind of the yarn stripe. Furthermore, either spun yarn comprised of a long fiber and short fiber or mixed yarn of them may be good, the same may be selected appropriately in accordance with requiring properties of a cogged belt A in short. If a braided number of the yarn stripes 6 constituting the round braided rope 7 are of an even number of pieces of at least 4 pieces, they are good whichever number they may be. A reason why the braided number of the yarn stripes are made into the uneven number of pieces of at least 4 pieces is that it is necessary to form the cylindrical hollow part 8 within the braided rope.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to fiber-reinforced rubber products, and particularly to improvements in reinforcing bodies embedded in the product body.

(Prior Art) Conventionally, rubber products such as belts, tires, and hoses have been required to have properties such as high strength, high modulus of elasticity, high dimensional stability, and high adhesiveness. In order to satisfy this requirement, reinforcing bodies such as reinforcing cords made of fibers and cloth-like materials are embedded in the rubber product body. As this reinforcing body, a twisted yarn made by twisting a plurality of threads is generally used, and the types are plied yarn, plied yarn,
It can be divided into single-twisted yarn, rung-twisted yarn, etc.

Currently, among the above-mentioned twisted threads, plied threads are most often used for reinforcing bodies of the above-mentioned rubber products.

However, in rubber products whose reinforcement is made of plied yarn, there are parts where the monofilaments strongly contact each other at deep angles within the plied yarn, so this strong contact area can cause premature wear, breakage, or a decrease in strength. However, there was a problem that the bending fatigue resistance deteriorated.

Therefore, as a fiber-reinforced rubber product that has improved the above-mentioned problem (bending fatigue resistance), a product in which the reinforcing body is composed of single-twisted yarn or rung-twisted yarn has been proposed (Japanese Patent Laid-Open No. 59-1
(See Publication No. 9744).

(Problem to be Solved by the Invention) However, as mentioned above, rubber products in which the reinforcing body is composed of single-twisted yarn or rung-twisted yarn have a structure that requires less stretching and dip treatment compared to rubber products in which the reinforcing body is composed of plied yarn. The tensile modulus of elasticity decreases, resulting in a decrease in dimensional stability.

By the way, braided cords have been used since ancient times. Among these braids, round braids have particularly excellent bending fatigue resistance due to their structural characteristics, and are also better than twisted threads in terms of dimensional stability, so they are used in rubber products. It is preferable to use it as a reinforcing body because it can improve both the physical properties of bending fatigue resistance and dimensional stability. However, since the above-mentioned round braid is braided into a cylindrical shape with a hollow part formed inside, it becomes flat when stretched, and although it is better than twisted thread in terms of dimensional stability, it is not fully satisfactory. It's not something you can do.

The present invention has been made in view of these points, and its purpose is to use a traditional round braid instead of twisted yarn, and to take appropriate means to bury the hollow part of the braid. In addition to improving the bending fatigue resistance of rubber products, the objective is to further improve the dimensional stability and further increase the bending rigidity.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention targets a rubber product in which a reinforcing body made of fibers is embedded in a rubber product body, and in this case, the above-mentioned reinforcement The body is composed of a round braid having a hollow part made of an even number of threads of four or more in a cylindrical shape, and a core thread provided in the hollow part of the round braid. do.

(Function) With the above configuration, in the present invention, the reinforcing body made of fibers embedded in the rubber product body is a round shape having a hollow part made of an even number of threads of 4 or more in a cylindrical shape. Since the core yarn is provided in the hollow portion of the round braid, the structural characteristic of the round braid is that uniform stress is applied to the monofilaments that make up the yarn, and the bending fatigue resistance is greatly improved.

Furthermore, the core yarn provided in the hollow portion prevents the flattening phenomenon during elongation, thereby improving the dimensional stability of the rubber product and also increasing the bending rigidity.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows a toothed belt A as a fiber-reinforced rubber product according to an embodiment of the present invention. The toothed bell) A consists of an extension rubber layer 1, a reinforcing body 2 made of fibers embedded in the extension rubber layer 1, and an extension on one side of the extension rubber layer 1 (lower side in FIG. 3). 3. A plurality of (only two are shown in FIG. 3) tooth portions β integrally formed of the same rubber as the rubber layer 1;・・・
A belt body 4 is provided as a product body, and a canvas 5 is integrally attached to the surface side of the teeth 3 of the belt body 4.

As a feature of the present invention, as shown in enlarged detail in FIG. 1 and FIG. A plurality of round braids 7 having a hollow part 8 braided into a cylindrical shape,
7. . . . and a core thread 9 inserted into the hollow portion 8 of each round braid 7. The yarns 6 may be made of inorganic fibers, organic fibers, metal fibers, etc., and may also be spun yarns made of long fibers and short fibers, or mixed yarns thereof. It may be selected as appropriate depending on the required performance of the attached belt A. Further, the number of yarns 6 that make up the round braid 7 is not limited as long as it is an even number of 4 or more. In this way, the reason why the number of strands to be driven is set to an even number of 4 or more is because it is necessary to form a cylindrical hollow part 8 inside the braid, and the hollow part 8 cannot be formed with an odd number of strands. Furthermore, the total denier number of the yarn 6, the monofilament denier number, etc. may be appropriately selected according to the required performance of the toothed belt A. Further, the type of the core yarn 9 may be the same type or different type of fiber as the yarn 6, depending on the use and purpose.

Further, the round braid 7 assembled as described above is made of, for example, epoxy resin, before being embedded in the extension rubber layer 1.
Adhesive treatment and stretching treatment are performed using a combination of adhesives such as isocyanate compounds, ethylene urea compounds, and resorcinol formalin latex (RFL). Note that the adhesive treatment method is to apply the adhesive to the reinforcing body 2.
The dipping method is preferable because it is necessary to uniformly impregnate the round braid 7 from the surface to the inside.

Next, a bending fatigue test was conducted on the toothed belt A according to the present example configured as described above, together with a comparative example, under the following conditions and procedures, and the results are shown in Table 1 below. In addition, in the numerical values in Table 1, the upper column represents the belt strength maintenance rate, and the lower column represents the belt elongation, for both the present example and the comparative example.

[Configuration of the toothed bell of this example) A] The round braid 7 constituting the reinforcing body 2 is made of 4-stranded Kevlar (trade name, manufactured by DuPont) 1500 de (
A hollow part 8 having a torque denier of 6000 de and a core thread 9 made of Tetron having a diameter of 330 de as inserted therein was used. This round braid 7 is first dipped in an adhesive made of an isocyanate compound to form a subcoat layer, and then,
A second coat layer is formed by dipping in resorcinol formalin latex (RFL) adhesive, and then CR
A top coat layer was formed by immersing it in paste rubber, and then a stretching process was performed. These stretched plural circular braids 7,7. ... are arranged in a spiral on the extension rubber layer 1 made of CR rubber, and after forming the toothed portion 3 made of CR rubber so as to embed the circular braid 7 thereon, the toothed portion 3
By applying a nylon canvas 5 to the surface and molding and vulcanizing it, the plurality of circular braids 7, 7. A toothed belt A was obtained in which a reinforcing body 2 in which a core thread 9 was inserted into each hollow part 8 was embedded in a belt main body 4. In addition, during the adhesive treatment, the adhesive is uniformly impregnated from the surface to the inside of the round braid 7.

[Structure of toothed belt of comparative example] The construction is the same as that of the present example except that the core thread 9 is not inserted into the hollow part 8 of the round braid 7.

[Procedure for bending fatigue test] As shown in Fig. 4, four large pulleys 10, 10,...
・and four small pulleys 11, 11 . arranged between adjacent large pulleys 10, 10. A belt bending tester equipped with... was prepared, and the toothed belt was passed between the large and small pulleys 10 and 11 of the belt bending tester, and a predetermined tension was applied to the toothed belt with the weight 12. I ran it in this condition. Note that the diameter of each of the small pulleys 11 is 30 mm. In addition, the toothed belt goes around and the four small pulleys 11, 11
．． . . . once each, or the number of times the belt is bent by each small pulley 11 four times, is defined as one cycle.

Table 1 As is clear from the test data in Table 1, both the present example and the comparative example were excellent in belt strength maintenance rate. However, there is a considerable difference in belt elongation between the two, especially when the number of belt bending is 1 x 108, it was 0.10% in this example, but 0.21% in the comparative example.
%, indicating that this example had better dimensional stability. This means that in this example, the round braid 7
This is because the core thread 9 is inserted into the hollow portion 8 of the braid 7, thereby regulating the flattening phenomenon when the round braid 7 is stretched.

As described above, in this embodiment, the reinforcing body 2 embedded in the belt main body 4 is made of an even number of threads 6.6. ...
Since the round braid 7 has a hollow part 8 that is braided into a cylindrical shape, the structural characteristics of the round braid 7 are that uniform stress is applied to the monofilaments that make up each yarn 6, which increases the durability. Bending fatigue resistance can be significantly improved.

In addition, in the above embodiment, the tensile modulus after stretching and dip treatment is larger than that of a reinforcing body made of twisted yarn due to the structure of the round braid 7, which reduces the dimensional stability of the toothed bell l-A. It can be improved.

Furthermore, in the above embodiment, since the core thread 9 is inserted into the hollow part 8 of the round braid 7 to fill the hollow part 8, the flattening phenomenon during stretching is regulated by the core thread 9,
Thereby, the dimensional stability of the toothed belt A can be further improved, and the bending rigidity can also be increased.

In addition, in the above embodiment, by selecting the material, thickness, etc. of the core thread 9, the toothed belt A (round braided cord 7)
It has the advantage that the bending rigidity of can be freely adjusted depending on the purpose and application.

Further, in the above embodiment, the toothed belt A is shown as the rubber product, but it is not limited to this, and may be a transmission belt or a conveyance belt such as a V belt, a flat belt, or a ribbed belt. Needless to say, the present invention can also be applied to rubber products other than belts, such as tires and hoses.

(Effects of the Invention) As explained above, according to the present invention, the reinforcing body 1 is inserted into the hollow part of the circular braid, which has a hollow part braided in a cylindrical shape with an even number of threads of four or more. Since the cord is provided in the fiber, it is possible to further improve the dimensional stability in addition to the improvement in bending fatigue resistance, and furthermore, it is possible to increase the bending rigidity.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is an enlarged longitudinal side view of a circular braid, FIG. 2 is an enlarged front view of the same, FIG. 3 is a longitudinal front view of a toothed belt, and FIG. 4 is a sectional view of a bent belt. It is a schematic block diagram of a test machine. 2... Reinforcement body 4... Belt body (product body) 6... Thread 7... Round braid 8... Hollow part 9... Core yarn A... Toothed belt (fiber Reinforced rubber products) 2

Claims (1)

[Claims] (1) A rubber product in which a reinforcing body made of fibers is embedded in a rubber product body, and the reinforcing body has a hollow part formed into a cylindrical shape by an even number of threads of 4 or more. A fiber-reinforced rubber product comprising a round braided cord and a core thread provided in the hollow portion of the round braided cord.