JPH022030B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a resin-rubber composite hose that is mainly used in hydraulic piping systems for machine tools, construction machinery, and the like. (Prior art) Conventionally, the above-mentioned hoses have been made by bonding a reinforcing layer made of braided or spirally braided fiber threads of polyamide, polyester, etc. to an inner tube of thermoplastic resin such as polyamide resin, polyethylene resin, polyester resin, etc. A hose is known in which the reinforcing layer is further covered with a rubber outer tube,
Such hoses are generally used in the applications listed above.
It is used under high pressures of Kg/cm ² or more, and in order to maintain durability such as pulling force and pressure resistance, it is customary to attach a connecting fitting to the end of the hose. (Problems to be Solved by the Invention) However, in such conventional hoses, the reinforcing layer is not provided in a state that is cut into the inner pipe, and the reinforcing layer is fixed to the inner pipe by adhesive. It has the following drawbacks. (1) In the initial stage of use, the reinforcing layer is fixed to the inner tube by adhesive, so the reinforcing layer may become disordered (disturbance of the braid angle due to sliding in the longitudinal direction of the hose).
However, the reinforcing layer restrains the inner tube, resulting in poor hose flexibility. (2) On the other hand, for long-term use, the adhesive strength between the reinforcing layer and the inner tube decreases, and eventually peeling occurs.As a result, the reinforcing layer becomes disordered, reducing the pressure resistance and pulling force. Further, durability performance such as impulse life is reduced due to internal fluid loaded by hydraulic equipment such as a pump, and impulse transmission is not performed sufficiently. (3) Disadvantages of (2) above, especially the need to lengthen the tightening part of the connecting fitting in order to maintain the pulling force, which increases costs and does not guarantee sufficient durability. The present invention was invented based on the above circumstances, and an object of the present invention is to provide a hose with excellent durability that solves the drawbacks of the conventional hoses. (Means for solving the problems) The present invention provides a fiber reinforced layer on the resin inner tube,
Furthermore, in a hose formed by covering the reinforcing layer with a rubber outer tube, the inner tube is made of a thermoplastic resin having a flow start temperature 5° to 15° C. higher than the vulcanization temperature of the outer tube, and the reinforcing layer is reinforced. The layer is configured as a braided layer formed of heat-shrinkable fiber yarn having a heat shrinkage rate of 2 to 8% at the vulcanization temperature of the outer tube, and a part of the reinforcing layer is attached to the outer peripheral surface of the inner tube. The gist is a hose constructed by incorporating The present invention will be explained in detail below. The inner tube 1 is made of thermoplastic resin such as polyamide resin (nylon 6, nylon 66, nylon 11, nylon 12, modified nylon copolymer, etc.), polyester resin, polyethylene resin, or the like. The outer tube 3 is made of general-purpose rubber such as chloroprene rubber (CR), nitrile rubber (NBR), ethylene propylene diene rubber (EPDM), butyl rubber (IIR), and chlorosulfonated polyethylene rubber (CSM). The reinforcing layer 2 is constructed by braiding heat-shrinkable fiber yarns such as polyamide, polyester, or vinylon. Thickness, number of threads, twist of yarn, braid density, etc. are appropriately selected and determined as necessary. An example of a method for manufacturing the hose 10 of the present invention as shown in FIG. 1 using the above-mentioned components is as follows. That is, after the inner tube 1 is extruded, the reinforcing layer 2 is braided onto the inner tube 1. [If necessary, the reinforcing layer 2 may be adhesively fixed to the inner tube 1. [After that, the outer tube 3 is extruded and coated on the reinforcing layer 2, and the outer tube 3 is further coated on the reinforcing layer 2.
Coat the lead pipe on top. Then, in this state, internal pressure is applied to the inner tube 1, and the desired hose 10 is obtained by heating and vulcanizing molding in this state. As explained above, these are the characteristics of the hose 10 of the present invention. As a means for forming a structure in which a part of the reinforcing layer 2 is bitten into the inner tube 1, under the above-mentioned conditions in which the outer tube 3 is covered with a lead pipe and the inner tube 1 is loaded with internal pressure. , unvulcanized outer tube 3
When heated and vulcanized, the resin constituting the inner tube 1 becomes fluidized (softened) due to the heat during vulcanization, and the reinforcing layer 2
Since the fiber threads constituting the reinforcing layer 2 are thermally shrunk, a portion of the reinforcing layer 2, that is, the fiber threads in contact with the inner tube 1, easily bite into the inner tube 1. At this time, the inner tube 1 of the reinforcing layer 2
The degree of biting into the hose and the dimensional stability of the hose depend on factors such as internal pressure, thermal shrinkage rate of the fiber thread, vulcanization temperature, vulcanization time, and resin flow start temperature (softening temperature). For example, the vulcanization temperature may be set at a temperature 5 to 15 degrees Celsius lower than the flow start temperature of the resin. (including modification by adding plasticizers and the like to achieve fluidization at lower temperatures). If the temperature exceeds the above temperature range at the lower limit, fluidization of the resin becomes noticeable, variations in the wall thickness, dimensions, etc. of the inner tube 1 increase, and the penetration of the reinforcing layer 2 into the inner tube 1 becomes disordered. If it comes off, the reinforcing layer 2 will not bite into the inner tube 1 sufficiently. Furthermore, the heat shrinkage rate of the fiber yarns constituting the reinforcing layer 2 is also important, and the commonly used molding conditions (150°C x 30°C) are also important.
In vulcanization), those having a heat shrinkage rate of 2 to 8% are preferred. If the lower limit of this range deviates from this range, the reinforcing layer 2 will not penetrate into the inner tube 1 sufficiently, and if it deviates from the upper limit, the reinforcing layer 2 will dig into the inner tube 1 too much, causing variations in the wall thickness, dimensions, etc. of the inner tube 1. This will have a negative impact on durability. Regarding the setting of the vulcanization sound intensity, it is necessary to pay attention to the above-mentioned considerations, but also the vulcanization characteristics of the rubber constituting the outer tube 3 or the reinforcing layer 2 and the inner tube 1 to the outer tube 3.
When adhering these, it is also necessary to consider suppressing a decrease in adhesive strength. In addition, in the present invention, the reinforcing layer 2 is effective when braided, and not all of the reinforcing layer 2 but a part thereof, that is, the inner tube 1 of the crossed upper thread and lower thread is in contact with the inner tube 1. If a part of the bobbin thread (fiber thread) is bitten, the bitten part becomes a restraining point and can prevent the overall braiding of the reinforcing layer 2 from becoming disordered. The braiding angle (resting angle) of the reinforcing layer 2, which accounts for the contribution rate, is maintained,
It maintains good pressure resistance and also exhibits great resistance against pulling out. In addition, the internal pressure applied to the inner tube 1 is 2 to 6 kg/cm ² depending on water pressure, etc., and the wall thicknesses of the inner tube 1 and outer tube 3 are also selected appropriately, and the flexibility of the hose is For improvement, an intermediate rubber layer can also be provided between the inner tube 1 and the outer tube 3. The usefulness of the present invention will be explained below based on Examples and Comparative Examples. Examples 1 to 6 Using the materials shown in Table 1, first, an inner tube (inner diameter 9.5 mm,
After extrusion molding (wall thickness 1.0 mm), heat at 150℃ on the inner tube.
× 5 polyester fiber threads (1000 denier/2 threads) with a heat shrinkage rate of 6% in 30 minutes are combined, and 2 to 3
The blades were braided at a resting angle with a braiding tension of Kg/braid (number of braids: 24). Next, an outer tube (outer diameter 16 mm, wall thickness 1.0 mm) was covered thereon. Furthermore, a lead pipe with a wall thickness of 2 mm was coated on the outer pipe, an internal pressure (water pressure) of 5 kg/cm ² was applied to the inner pipe, and heat vulcanization molding was performed under the conditions shown in Table 1. The desired hose was obtained by cutting into the tube. Regarding the hose obtained in this way, Table 1
Performance evaluations were performed as described in . In addition, the length of the joint part (tightening part) of the connection fitting is 28 mm.
The tightening rate was 30%. Comparative Example 1 After extruding an inner tube (inner diameter 9.5 mm, wall thickness 1.0 mm) using the materials shown in Table 1, the inner tube was heated at 150°C.
A polyester fiber yarn having a heat shrinkage rate of 10% after 30 minutes was braided in the same manner as in the example. At this time, adhesive was applied on the inner tube to fix the reinforcing layer to the inner tube. Next, an outer tube (outer diameter 16 mm, wall thickness 1.0 mm) was covered thereon. In the thus obtained hose, the reinforcing layer does not dig into the inner tube. The performance of this hose was evaluated in the same manner as in the examples. In addition, the length of the joint part (tightening part) of the connection fitting is 40 mm.
The tightening rate was 30% as in the example. Comparative Examples 2 to 3 After extruding an inner tube (inner diameter 9.5 mm, wall thickness 1.0 mm) using the materials shown in Table 1, five polyester fiber threads (1000 denier/2 threads) with a heat shrinkage rate of 6% were extruded. The yarns were combined and braided in the same manner as in the example. Next, an outer tube (outer diameter 16 mm, wall thickness 1.0 mm) was covered thereon, and heat vulcanization molding was performed under the conditions shown in Table 1. The performance of the thus obtained hose was evaluated. Incidentally, the same connecting fittings as in the example were used, and the tightening rate was also the same. Further, notes regarding each performance evaluation test shown in Table 1 are shown below. (Note 1) Bursting pressure (Kg/cm ² ) (Note 2) Tensile strength of connection fittings and hose (Kg),
Measurement temperature: 20℃ (Note 3) Impact durability test (according to JISB-8362-1983) (Fluid oil temperature: 93℃, maximum impact pressure: 140Kg/cm ² × 150%) (Note 4) Minimum bending radius ( mm)

[Table] As is clear from the above results, in Comparative Example 1, the reinforcing layer did not dig into the inner tube, and in Comparative Example 3, the reinforcing layer did not dig into the inner tube sufficiently. There is a problem with durability. In Comparative Example 2, the flow start temperature of the inner tube material was the same as the vulcanization temperature of the outer tube rubber, so even though internal pressure was applied, there were large variations in the wall thickness, dimensions, etc. of the inner tube, and a good product could not be obtained. Nakatsuta. On the other hand, the hoses of each example had high pulling force, pressure resistance,
It was confirmed that the product has excellent durability and is of high quality and has a long life with no decrease in impulse transmission efficiency. (Effects of the Invention) The hose of the present invention as described in detail above can be used not only at the initial stage of use but also during long-term use, in the vicinity of the tightening part of the connection fitting of the hose caused by impulses from hydraulic equipment such as pumps. Even when the hose pulsates (expansion and contraction in the radial direction of the hose) or when the hose is bent during use, the braid of the reinforcing layer is not disturbed, and the pulling force and pressure resistance of the tightening part of the hose connection fitting are maintained. Since the durability performance of the hose can be ensured well, the life of the hose can be significantly improved, and impulse transmission can also be carried out smoothly. Furthermore, there is no need to increase the length of the connection fitting tightening part, which was conventionally done to ensure the life of the hose.In fact, according to the hose of the present invention, the length can be reduced by about 30% compared to the conventional hose. However, it does not impair its performance, and has significant practical effects such as significant cost reduction. Further, according to the present invention, even if the reinforcing layer is not fixed to the inner tube or the outer tube by adhesive, the braiding of the reinforcing layer can be prevented from becoming disordered simply by biting a part of the reinforcing layer into the inner tube. It can be moved while the reinforcing layer is biting in, and it also has additional effects such as not impairing the flexibility of the hose.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the hose of the present invention. 1... Inner tube, 2... Reinforcement layer, 3... Outer tube, 10
……hose.

Claims (1)

[Scope of Claims] 1. A hose comprising a resin inner tube provided with a fiber reinforcing layer and a rubber outer tube coated on the reinforcing layer, wherein the inner tube is heated to a vulcanization temperature of 5°C higher than the vulcanization temperature of the outer tube. A braided braid made of a thermoplastic resin with a flow start temperature that is 15° to 15°C higher, and a reinforcing layer made of heat-shrinkable fiber yarn with a heat shrinkage rate of 2 to 8% at the vulcanization temperature of the outer tube. A hose characterized in that the reinforcing layer is formed as a layer and a part of the reinforcing layer is bitten into the outer peripheral surface of the inner tube.