JPS6363798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a rubber hose reinforced with nylon filament yarns, particularly a nylon reinforced rubber hose in which each nylon filament yarn is wound at intervals without being tightly wound. be.

As shown in FIG. 1, the rubber hose reinforced with fibers includes one in which reinforcing fibers 3 are wound around an inner tube rubber 1 in close contact with each other and the reinforcing fibers 3 are covered with a rubber cover 2; As shown in FIG. 2, there is a type in which reinforcing fibers 3 are wound around an inner tube rubber 1 at intervals, and the reinforcing fibers 3 are covered with a rubber cover 2.

By the way, as for those using nylon filament yarns as reinforcing fibers, it is generally known that the nylon filament yarns are placed in close contact with each other as shown in Figure 1, but the nylon filament yarns are closely spaced as shown in Figure 2. In particular, those that are wound using the braid method (one thread is wound vertically and the other thread alternately), or those that are wound using the spiral method (one thread is wound spirally and then wrapped around the other thread) There are relatively few cases where the other thread is wound spirally.

The reason for this is that the nylon filament thread shrinks due to the heat generated during vulcanization of the rubber hose, and becomes embedded in the inner tube rubber. That is, fiber-reinforced rubber hoses are generally made by extruding an inner tube rubber, winding fibers around it, supplying a cover rubber around it, extruding it, and then vulcanizing it. When vulcanization is performed from the unvulcanized state shown in the cross-sectional view of FIG. This is because there is a problem in that unevenness occurs on the inner and outer surfaces of the rubber 1 and the cover rubber 2. In particular, when the fibers are wound around the inner tube rubber under tension as in the above-mentioned blade method or spiral method, the fibers are elongated by the tension, and this elongated amount is directly contracted by the heat of vulcanization. Therefore, the amount that a nylon filament yarn shrinks during vulcanization is the sum of the amount of contraction the yarn itself has and the amount of elongation caused by the tension when the yarn is wound in a braided or spiral manner. Become. Note that when the thread densely covers the inner tube rubber as shown in Figure 1, even if the thread contracts, the pressure will be applied to the entire surface of the inner tube rubber, so the thread will not be dug in and the resulting Problems with uneven rubber hoses rarely occur.

In order to overcome the drawbacks of using nylon filament yarn and winding the yarn at intervals as shown in FIG. 2, it is necessary to reduce the shrinkage of the nylon filament yarn during vulcanization.

One way to reduce the shrinkage of fibers for reinforcing rubber hoses is to give the fibers a thermal history equivalent to vulcanization in advance, that is, heat them in a steam atmosphere in advance, so-called moist heat treatment. There is.

However, in the case of nylon filament yarn, it has a lower elastic modulus and is easier to stretch than other hose fibers, such as rayon, vinylon, polyester, etc., and its elastic modulus further decreases significantly when subjected to moist heat treatment. . Therefore, when using nylon filament yarn, even if you wind it around a hose with a low tension, the amount of elongation will be large, making it impossible to reduce the amount of shrinkage overall, so this is not an effective countermeasure. Must not be.

Therefore, the present invention has discovered a treatment method that reduces the shrinkage rate of the nylon filament yarn itself and hardly causes a decrease in the elastic modulus. By winding the nylon filament yarn in such a way that the yarns do not come into close contact with each other, and then vulcanizing the nylon filament yarn after covering it with cover rubber, a rubber hose is obtained in which the nylon filament yarn does not get stuck.

That is, in order to prevent a decrease in the elastic modulus, the nylon filament yarn is subjected to a dry heat treatment (commonly known as heat setting) in which it is heated under tension at a high temperature under normal humidity as a pretreatment, and then the hose is heated without tension. When the above-mentioned moist heat treatment corresponding to the steam vulcanization state described above is applied, a nylon filament yarn is obtained which does not significantly reduce its elastic modulus and hardly shrinks due to the heat during vulcanization. The present invention involves preparing a nylon filament yarn that has undergone the above treatment, and winding it spirally around the outer circumference of an inner tube rubber with intervals between the yarns. The tube is coated with a cover rubber and then vulcanized, thereby making it possible to prevent the nylon filament yarn from getting stuck in the inner tube rubber as described above.

Next, experiments conducted regarding the present invention will be explained.

The samples were a nylon filament yarn (hereinafter referred to as raw yarn) made by twisting two 6,6 nylon filaments (1260 denier), and a nylon filament yarn (hereinafter referred to as raw yarn) that was subjected to dry heat treatment at 240℃ for 80 seconds. (hereinafter referred to as "dry heat treated yarn"), nylon filament yarn (hereinafter referred to as "wet heat treated yarn") obtained by subjecting the raw yarn to wet heat treatment at 150°C for 30 minutes in a steam oven; Thereafter, a nylon filament yarn (hereinafter referred to as "mainly treated yarn") which had been further subjected to the above-mentioned moist heat treatment was prepared.

A tensile test was then conducted to measure the elongation of these four types of nylon filament yarns. The results are shown in Figure 5. In the figure, A is raw yarn,
B shows the results for the dry heat treated yarn, C shows the results for the wet heat treated yarn, and D shows the results for this treated yarn. As shown in the figure,
The elastic modulus of the dry heat treated yarn B is lower than that of the raw yarn A, but the elastic modulus of the wet heat treated yarn C is much lower. On the other hand, the elastic modulus of the treated yarn D is slightly lower than that of the dry heat treated yarn B, but much higher than that of the moist heat treated yarn C.

Next, use these four types of nylon filament threads.
Similar to the moist heat treatment above, place in a steam pot at 150℃ for 30 minutes.
The shrinkage rate was measured before and after the treatment. As a result, the raw yarn A was 19.1%, the dry heat treated yarn B was 3.0%, the moist heat treated yarn C was 0.5%, and the fully treated yarn D was
It was 0.5%.

As is known from the above experimental results, when nylon filament yarn is used to reinforce rubber hoses,
It can be seen that although the raw yarn does not elongate much due to tension during winding, it contracts significantly during vulcanization. Furthermore, a dry heat treated yarn subjected to only dry heat treatment has a larger elongation during winding than the original yarn, and also has a considerably larger shrinkage during vulcanization, resulting in a larger overall amount of shrinkage. Furthermore, it can be seen that the moist heat treated yarn subjected only to the moist heat treatment has almost no shrinkage during vulcanization, but elongation during winding is extremely large, resulting in a large amount of shrinkage. On the other hand, this treated yarn, which was subjected to wet heat treatment after dry heat treatment, has an elongation during winding that is similar to the above dry heat treated yarn, and almost no shrinkage during vulcanization, similar to the above wet heat treated yarn. Therefore, the overall amount of shrinkage is smaller than the other three types. Therefore, a rubber hose in which this treated yarn is applied for reinforcement, is wound around an inner tube rubber extruded by a conventional method, is further covered with a cover rubber, and then vulcanized is vulcanized. The reinforcing fibers do not get stuck due to shrinkage and the resulting unevenness on the inner and outer surfaces of the hose does not occur, and the reinforcing effect is good and the appearance is excellent.The fluid flow resistance of the fluid inside the hose is also high due to the unevenness on the inner surface of the hose. That's not going to happen.

[Brief explanation of drawings]

Figure 1 is a partially cutaway side view of a rubber hose in which reinforcing fibers are wound closely together, and Figure 2 is a partially cutaway side view of a rubber hose in which reinforcing fibers are wound at intervals. The side view, FIGS. 3 and 4 are cross-sectional views of a rubber hose in which reinforcing fibers are wound at intervals, and FIG. 3 shows the state before vulcanization, and FIG. 4 shows the state after vulcanization. FIG. 5 is a diagram showing experimental results regarding the present invention. 1... Inner tube rubber, 2... Cover rubber, 3... Nylon filament thread for reinforcement.

Claims (1)

[Claims] 1 Prepare a nylon filament yarn that has been subjected to a dry heat treatment in which it is heated under normal humidity while applying tension, and then subjected to a wet heat treatment in which it is heated in a steam atmosphere without applying tension, and this nylon filament yarn is Wind the thread around the outer circumference of the inner rubber tube in a spiral shape with intervals between the threads,
A method for manufacturing a nylon-reinforced rubber hose, which comprises covering the outer periphery of an inner rubber tube wound with nylon filament thread with a cover rubber and vulcanizing the hose.