JPH0624326A - Hydraulic brake hose for automobile - Google Patents

Abstract

PURPOSE:To provide a hydraulic brake hose having X reduced moisture permeability. CONSTITUTION:In a brake hose comprising a first fiber reinforcement yarn layer 2 applied on an outer circumference of an inner surface rubber layer 1, an intermediate rubber layer 3 applied on an outer circumference of the first reinforcement yarn layer '2, a second fiber reinforcement yarn layer 4 applied on an outer circumference of the intermediate rubber layer 3, and an outer surface rubber layer 5 applied on an outer circumference of the second reinforcement yarn layer 4, the inner surface rubber layer 1 comprises ethylene- propylene-diene rubber compound, the intermediate rubber layer 3 comprises regular butyl rubber compound in a thickness of 0.1-0.5mm, and the outer surface rubber layer 5 comprises blended matter of ethylene-propylene-diene rubber/ chloroprene rubber at a weight ratio of 10/0-3/7. Vapor lock in the brake hose can thus be prevented to improve safety, heat resistance is improved, and a long life can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake hose for automobiles, and more particularly to a hydraulic brake hose with reduced moisture permeability.

[0002]

2. Description of the Related Art As shown in FIG. 1, a hydraulic brake hose for an automobile has a first fiber reinforcing yarn layer 2 on the outer periphery of an inner rubber layer 1.
The intermediate rubber layer 3, then the second fiber reinforcing yarn layer 4 and the outer rubber layer 5 are provided on the outer periphery thereof. The material of each layer is styrene-butadiene rubber (SB
R) type rubber, natural rubber (NR) in the intermediate rubber layer 3,
The outer rubber layer 5 is made of a blend rubber mainly composed of chloroprene rubber (CR) or an ethylene-propylene-diene rubber (EPDM) alone or as a blend rubber. Polyvinyl alcohol (PVA) yarns having a small elongation are usually used for the fiber reinforcing yarn layers 2 and 4.

The selection and combination of such structures and materials are determined in consideration of the bending fatigue resistance, the repeated pressurization resistance, and the brake fluid resistance to the brake fluid required for the hydraulic brake hose for automobiles. ing.

[0004]

When the brake hose is mounted on an actual vehicle and used for a long period of time, moisture is absorbed from the outside of the hose to the outer rubber layer and the second layer by the breathing action caused by bending and repeated pressurization.
It penetrates into the brake fluid through the fiber reinforcing yarn layer, the intermediate rubber layer, the first fiber reinforcing layer, and the inner rubber layer. If this amount of water absorption increases, the boiling point of the brake fluid decreases, vapor lock occurs under severe temperature conditions, and in the worst case, the brake may not work. Therefore, there is a demand for a brake hose that does not allow water to easily penetrate.

As a means for reducing the amount of water permeation, there is a method of using a metal pipe or a fluororubber as a constituent material of a hose. However, flexibility and rocking durability are provided in a brake line connecting a vehicle body and wheels. Therefore, when a metal pipe is used, it is damaged by fatigue. Further, although reduction of water permeation can be achieved by using fluororubber, it is very expensive and is not industrially practical.

Regular butyl rubber (IIR) has a very low water permeability and can prevent the permeation of water.
If it comes into contact with the brake fluid, it will soften and deteriorate over a long period of use.

An object of the present invention is to provide a brake hose having a structure capable of reducing water permeability without impairing the properties required for each layer of a hydraulic brake hose for automobiles.

[0008]

That is, the hydraulic brake hose for automobiles of the present invention comprises an inner rubber layer made of an EPDM compound, an intermediate rubber layer made of an IIR compound having a wall thickness of 0.1 to 0.5 mm, and an outer rubber layer. Layer is 10 by weight ratio of EPDM / CR
It is characterized by comprising a blend of / 0 to 3/7.

[0009]

Actions and Examples The rubber material of each rubber layer constituting the hydraulic brake hose for automobile will be described below. First, an EPDM compound is used for the inner rubber layer. It is conceivable to use IIR with extremely low water permeability for the inner rubber layer, but IIR exhibits softening deterioration behavior with respect to the brake fluid, and also has a low impact resilience, so there is a problem with the sealing pressure characteristic of the mouthpiece. It is not appropriate because it is. EPDM has a lower water permeation than the conventional SBR (styrene-butadiene rubber) system, and is excellent in brake fluid resistance, heat resistance, and sealing pressure characteristics at high temperatures.

Regular IIR having extremely low moisture permeability is used for the intermediate rubber layer. IIR of the intermediate rubber layer is I
Although the purpose of performance can be achieved by IR alone, IIR may cause variation in wall thickness at the time of taking out from a roll after thin layer rolling by a roll or during thin layer extrusion coating. Therefore,
In order to facilitate workability without impairing the effect of low water permeability, it is desirable to mix the partially crosslinked IIR in an amount of 5 to 30% by weight. If the amount of the partially crosslinked IIR is small, the processability is not improved, and if it is too large, the dispersibility of the compound may be deteriorated, and it is necessary to prolong the kneading time.

For the outer rubber layer, EPDM or a blend of EPDM and CR having excellent heat resistance, weather resistance and ozone resistance is used. The CR blend is up to 70% by weight, preferably up to 60% by weight. If the CR is too large, ozone resistance and cold resistance are deteriorated.

In the brake hose of the present invention, the amount of water penetrating into the brake fluid is reduced and the heat resistance is improved, so that the safety can be improved and the life of the brake hose can be extended about twice. You can

The brake hose of the present invention can be manufactured by a method similar to the conventional method. That is, the extruded tube is covered on the mandrel and the first reinforcing yarn is braided.
After covering the outer periphery with an intermediate rubber layer, the second reinforcing yarn is braided and at the same time an adhesive treatment is applied. Then, it can be manufactured by coating the outer surface rubber and steam vulcanizing. The thickness of each rubber layer is usually 0.8 to 1.2 mm for the inner rubber layer 1, 0.1 to 0.5 mm for the intermediate rubber layer 3, 1.0 to 1.4 mm for the outer rubber layer 5, and the fiber reinforcing yarns 2 and 4 are PVA yarns. Conventionally used yarns such as can be used.

The function of the intermediate rubber layer is to prevent the frictional fatigue between the reinforcing threads by interposing it between the reinforcing threads, and with a thinness of 0.1 to 0.5 mm, further 0.2 to 0.4 mm. Fully functional. If the thickness of the intermediate rubber layer is too large, the caulking stress is dispersed in the intermediate rubber layer when the fitting is joined to the mouth fitting by the caulking, and the sealing pressure characteristic is deteriorated.

Next, the hydraulic brake hose of the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited to such Examples.

Example 1 EPDM compound as the inner rubber layer, regular IIR compound as the intermediate rubber layer, and EPDM / CR as the outer rubber layer.
(90/10 weight ratio) A hydraulic brake hose for automobiles was produced by the following method using a blend and a PVA-based fiber reinforcing yarn.

After the inner tube was extruded by an extruder, the mandrel was inserted, and the outer circumference of which the first reinforcing yarn was braided by a braiding machine was coated with intermediate rubber rolled to 0.3 mm by a roll machine. Blade the second reinforcing yarn. After the second reinforcing yarn blade, the outer periphery is subjected to RPL adhesive treatment. After that, the outer surface rubber is covered with an extruder and vulcanized with a vulcanizing can. The finished hose has an inside diameter of 3.4 mm and an outside diameter of 10.5
mm and the wall thickness was 3.55 mm.

The water permeability and the high temperature bending fatigue resistance of the produced brake hose were examined in the following manner. The results are shown in Table 1.

(Moisture Permeability) Brake fluid (GC # 418 AA (DOT4) manufactured by CCI) was enclosed in a hose having a length of 305 mm so that the hose was completely immersed in water at 70 ° C.
After soaking for a period of time, the amount of water in the brake fluid is quantified by the Karl Fischer method.

(High temperature bending fatigue resistance) Install a brake hose (300mm) as shown in Fig. 2, and put 50kgf / cm ² inside the hose.
Liquid pressure is applied, and this is fixed in the atmosphere at 120 ° C with the B side mouth fitting fixed, and the A side mouth fitting is bent vertically (stroke length 13
cm. Cycle 150 times / min) and check the number of bends until the hose bursts.

Examples 2 to 4 Example 1 except that the material for the rubber layer was changed to that shown in Table 1.
A hydraulic brake hose for automobiles was produced in the same manner as in 1. and moisture permeability and high temperature bending fatigue were examined in the same manner as in Example 1. The results are shown in Table 1.

Incidentally, in Examples 3 to 4 in which the IIR containing 10% by weight of the partially crosslinked IIR was used, the processability of the intermediate rubber layer was considerably improved.

Comparative Examples 1 to 3 Example 1 except that the material for the rubber layer was changed to that shown in Table 1.
A hydraulic brake hose for automobile was manufactured in the same manner as in 1. and moisture permeability and high temperature bending fatigue resistance were examined in the same manner as in Example 1. The results are shown in Table 1.

The abbreviations in Table 1 are as follows.

EPDM: ethylene-propylene-diene rubber SBR: styrene-butadiene rubber NR: natural rubber IIR: regular butyl rubber CR: chloroprene rubber partially crosslinked IIR: degree of crosslinking 70 to 85%

[0026]

[Table 1]

[0027]

EFFECT OF THE INVENTION By using EPDM having low moisture permeability and excellent heat resistance for the inner rubber layer and IIR having extremely low moisture permeability for the intermediate rubber layer, it penetrates into the brake fluid from the outside of the hose. By reducing the amount of water, preventing vapor lock that may lead to personal injury, and improving heat resistance, the hose can have a long life, and can play a safer role as a brake hose for a longer time. You can Further, when the partially crosslinked IIR is mixed in the intermediate rubber layer, the workability is remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing the structure of an automotive hydraulic brake hose of the present invention.

FIG. 2 is an explanatory diagram of a high temperature bending fatigue resistance test used in Examples of the present invention.

[Explanation of symbols]

 1 Inner Surface Rubber Layer 2 First Fiber Reinforcement Thread Layer 3 Intermediate Rubber Layer 4 Second Fiber Reinforcement Thread Layer 5 Outer Surface Rubber Layer

Claims (2)

[Claims] 1. A first fiber-reinforced yarn layer is provided on the outer periphery of an inner rubber layer, and an intermediate rubber layer is provided on the outer periphery of the first fiber-reinforced yarn layer,
A second fiber reinforcing yarn layer is applied to the outer periphery of the intermediate rubber layer,
In a brake hose with an outer rubber layer on the outer circumference of the reinforcing thread layer, the inner rubber layer is made of an ethylene-propylene-diene rubber compound, the intermediate rubber layer is made of a regular butyl rubber compound having a wall thickness of 0.1 to 0.5 mm, and the outer rubber layer is made. A hydraulic brake hose for vehicles, characterized in that the layer comprises a blend of ethylene / propylene / diene rubber / chloroprene rubber in a weight ratio of 10/0 to 3/7. 2. The intermediate rubber layer contains 5 to 5 partially cross-linked butyl rubber.
The brake hose according to claim 1, which is mixed in an amount of 30% by weight.