JPH06206283A - Brake hose - Google Patents

Abstract

PURPOSE:To suppress composite deterioration due to impregnation of moisture and improve pressure resistance, fatigue resistance, high reliability, etc., on the basis of forming an inner layer rubber of a brake hose of halogenated butyl rubber and a specific ratio of ethylene-propylene-diene rubber. CONSTITUTION:A brake hose comprises an inner layer rubber 1, and a first fiber reinforcing layer 21, an intermediate rubber layer 22, a second fiber reinforcing layer 23 and an outer layer rubber 3 sequentially arranged on an outer periphery of the rubber 1. In this case, the rubber 1 is formed of halogenated butyl rubber and ethylene-propylene-diene rubber(EPDM). The EPDM is set to 30-70wt.% to total quantity with the butyl rubber. The layer 22 is set in thickness to 0.05-0.5mm, so set that permeability constant of brake fluid or moisture at 40 deg.C is 0.5-10 times as large as that of the rubber 1 and set to five times or less as large as that of the rubber 3. Further, the EPDM is set to 20 or more of iodination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake hose used for automobiles and the like.

[0002]

Brake hoses are used as hydraulic pressure transmission hoses connecting a vehicle body and wheel calipers, and are important safety parts for automobiles (vehicles) and the like.

Generally, a brake hose is provided with an inner rubber layer through which a brake fluid flows, an intermediate rubber layer provided on the outer periphery of the inner layer rubber with a first fiber reinforcement layer interposed therebetween, and a second fiber reinforcement layer provided on the outer periphery thereof. It is composed of an outer rubber layer.

Conventionally, in the above-mentioned brake hose, styrene-butadiene rubber (hereinafter referred to as SBR) excellent in brake fluid resistance and EPDM are used as the inner rubber layer, and EPDM is the most popular as the fiber reinforcing layer because of its excellent reinforcing property. Polyvinyl alcohol fiber (commercially available from Kuraray Co., Ltd. as “vinylon fiber”), or a braided layer of rayon fiber, polyamide fiber, polyester fiber, etc.,
The intermediate rubber layer is made of natural rubber that has good adhesion to the fiber reinforcement layer and has excellent fatigue resistance, and the outer layer rubber is made of chloroprene rubber (hereinafter, CR) that is excellent in weather resistance and mechanical properties.
, Or a blend rubber mainly composed of CR is used.

[0005]

However, although the conventional brake hose having such a structure exhibits excellent pressure resistance, fatigue resistance, and high reliability under normal use conditions, it does not operate at high temperatures. It has been found that a small amount of water permeates from the outer layer when used for a long period of time under the condition of high humidity and corrosive atmosphere. Moreover, it has been found that the amount of water permeation increases when a hygroscopic hose constituent material or a hose fluid substance such as boric acid ester added to the brake fluid is present in the hose. In addition, the hygroscopic borate ester, together with the hygroscopic moisture, may cause composite deterioration of the hose constituent material, for example, the fiber reinforcing layer.

Therefore, it is an object of the present invention to provide a brake hose in which moisture in the atmosphere does not permeate into the inner rubber layer.

[0007]

In view of the above problems, the present invention includes a halogenated butyl rubber and EPDM in the inner rubber layer to prevent moisture in the atmosphere from permeating into the inner rubber layer, and the EPDM is halogenated. It is intended to provide a brake hose having 30 to 70% by weight based on the total amount of butyl rubber.

The intermediate rubber layer has a thickness of 0.05 to 0.5.
The permeation coefficient of brake fluid or water at 40 mm and 40 ° C is 0.5 to 10 times that of the inner rubber layer and 5 times or less that of the outer rubber layer.

The EPDM has an iodine value of 20 or more, and the halogenated butyl rubber and EPDM have a sulfur-vulcanized structure.

The reason why EPDM is set to 30 to 70% by weight based on the total amount of the halogenated butyl rubber is that the brake fluid or moisture permeation inhibiting property and the brake fluid resistance are the best. The reason why the iodine value of EPDM is limited to 20 or more is that if it is less than that, sufficient mechanical properties cannot be obtained. Other structures of the EPDM are not particularly limited, but those having an ethylene content of 40 to 60% by weight and the third component of ENB type are preferable from the viewpoint of cold resistance and the ability to prevent permeation of brake fluid and water. The reason why the vulcanization system is limited to sulfur vulcanization is that other vulcanization systems, for example, peroxide vulcanization, have low mechanical strength and cause a problem of metal corrosivity due to dehalogenation reaction.

Further, the thickness of the intermediate rubber layer is 0.05 to 0.
The reason why it is limited to 5 mm is that the moisture permeation inhibiting property and the hose outer diameter can be balanced. The permeability coefficient of the brake fluid or water at 40 ° C is 0.5 to 1 of the inner layer rubber.
The reason for limiting the amount to 0 times or less than 5 times that of the outer layer rubber is that if it is less than 0.5, boric acid will be accumulated in the first fiber reinforcing layer and the dissolution of vinylon fibers will be promoted.
If it is more than 0 times, sufficient water permeation inhibiting property cannot be exhibited, and if it exceeds 5 times that of the outer rubber layer, dissolution of vinylon fiber due to boric acid occurs in the second fiber reinforcing layer in a short time. Because I will do it.

Further, as the outer layer rubber, any rubber having excellent weather resistance and mechanical properties may be used, and a CR type blend rubber, EP
DM or the like can be used.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The brake hose of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the structure of a brake hose according to an embodiment of the present invention. This brake hose includes an inner rubber layer 1 and a first fiber reinforcement layer 2 on the outer periphery thereof.
1 and the EP provided on the outer periphery of the intermediate rubber layer 22 via the second fiber reinforcing layer 23.
The outer rubber layer 5 is made of DM.

The inner layer rubber 1 is a halogenated butyl rubber,
It comprises EPDM, which is 30 to 70% by weight, based on the total amount with halogenated butyl rubber.

The intermediate rubber layer 22 has a thickness of 0.05 to 0.5.
At 40 mm and 40 ° C., the permeability coefficient of the brake fluid or water is 0.5 to 10 times that of the inner rubber layer and 5 times or less that of the outer rubber layer.

The first fiber reinforcing layer 21 and the second fiber reinforcing layer 23
Is composed of a braid of vinylon fibers.

In the above construction, the first and second fiber reinforcing layers are vinylon fiber braid layers, and the outer rubber layer is C.
Eight types of different materials for the inner rubber layer and the intermediate rubber layer as shown in Table 1 as R (Examples 1 to 3 and Comparative Examples 1 to 5)
Brake hoses were manufactured, and the brake fluid permeability, water permeability, and brake fluid resistance of each were measured by the following test methods. (1) Brake fluid permeability test inner diameter 10 mm, rubber thickness 1.0 mm, were weighed weight W ₀ of the sample obtained by sealing the brake fluid to the rubber tube of length 80 mm, allowed to stand for 168 hours in then 70 ° C..
After taking out, the weight W ₁ of the sample is weighed, and the difference between W _{1 and} W ₀ is obtained as the transmission amount. The evaluation of the brake fluid permeability is shown as a comparative value when the permeation amount of Comparative Example 1 is 1. (2) Water permeability test Prepare a hose with a length of 305 mm with metal fittings on both ends.
After preliminary drying at 100 ° C. for 24 hours, a brake fluid is put into the hose, and then the metal fittings at both ends are sealed to obtain a sample. Next, the sample is immersed in distilled water at 70 ° C. for 72 hours. Finally, the brake fluid of the sample was collected, and the water content in the brake fluid was measured by the Karl Fischer method. The evaluation of the water permeability is shown as a comparative value when the permeation amount of Comparative Example 1 is 1. (3) Brake fluid resistance 150 ° C based on the immersion test method of JIS K6301
At 72, the hardness change after immersion for 72 hours was determined.

[0019]

[Table 1] As can be seen from the measurement results in Table 1, EPD is used as the inner rubber layer.
M is 30 to 7 relative to the total amount with halogenated butyl rubber
In Examples 1 to 3 in which 0% by weight was blended, the brake fluid and water permeation inhibiting properties were extremely good. On the other hand, Comparative Examples 2 and 3 in which the inner rubber layer or the inner rubber layer and the intermediate rubber layer are made of EPDM
In comparison with Comparative Example 1 which does not use EPDM at all, the brake fluid and water permeation inhibiting property can be made small to some extent, but Examples 1 to 3 have not been reached. Further, in Comparative Example 4 in which EPDM was blended as the inner layer rubber in an amount of 90% by weight based on the total amount of the halogenated butyl rubber, the permeation inhibiting property was E
No difference from PDM alone can be obtained, and conversely EP as inner layer rubber
Comparative Example 5 in which DM was blended in an amount of 10% by weight based on the total amount of the halogenated butyl rubber was severely deteriorated by the brake fluid and had a practical problem.

Next, as shown in Table 2, eleven kinds (Examples 4 to 8 and Comparative Examples 1 and 8) in which the materials of the inner rubber layer, the intermediate rubber layer and the outer rubber layer and the thickness of the intermediate rubber layer were changed 7-1
The brake hose of 1) was manufactured, and a brake fluid permeation test under moist heat was carried out to obtain the relationship between the amount of boron accumulated in the first and second fiber reinforcing layers and the ratio of the brake fluid permeation coefficient of each rubber layer. A water permeability test was also conducted in parallel with this. A correlation is obtained between the amount of boron and the amount of vinylon fiber dissolved by boric acid. The brake fluid permeation test under moist heat was performed as follows.

A hose having a length of 200 mm with fittings at both ends is prepared, a brake fluid is put into the hose, and then the fittings at both ends are sealed to obtain a sample. Next, the sample is placed at 90 ° C
After leaving it in a constant temperature and humidity of 0% RH for 720 hours, this is taken out, the vinylon fibers of the first and second fiber reinforcing layers are collected, and heated at 500 ° C. for 1 hour to be incinerated. Pure water was added to the ashed sample, the sample was heated at 40 ° C. for 2 hours for extraction, the insoluble matter was filtered, and then the boron in the filter was quantified by inductively coupled plasma emission spectrometry.

[0022]

[Table 2] In the measurement results of Table 2, the amount of boron in the fiber reinforcing layer was 0.
If it exceeds 20 to 0.25%, the dissolution of vinylon fibers can be visually confirmed. As can be seen, in Comparative Example 7 in which the brake fluid permeability coefficient of the intermediate rubber layer at 40 ° C. is less than 0.5 times that of the inner rubber layer, Comparative Example 7 in the first fiber-reinforced layer is 0.5 times more than in Example 5. As the amount of boron increases, the risk of vinylon fiber dissolving increases. On the contrary, in Comparative Example 8 which exceeds 10 times, the amount of water permeation cannot be effectively reduced as compared with Comparative Example 1 as compared with Example 4 which is 7 times. Therefore, as in Examples 4 to 8, it is understood that the brake fluid permeability coefficient of the intermediate rubber layer is preferably 0.5 to 10 times that of the inner rubber layer. Further, in Comparative Example 9 in which the brake fluid permeability coefficient of the intermediate rubber layer exceeds 5 times that of the outer rubber layer, the amount of boron in the second fiber reinforcing layer, not in the first fiber reinforcing layer, increases. Furthermore, the thickness of the intermediate rubber layer is 0.
Comparative Example 10 having a thickness of less than 05 mm did not have sufficient water permeation inhibiting property as compared with Example 7 having a thickness of 0.05 mm, and
In Comparative Example 11 thicker than 0.5 mm, the dissolution of vinylon fibers in the second fiber reinforcing layer is promoted as compared with Example 8 having a thickness of 0.5 mm. Therefore, it is understood that it is preferable to set the thickness of the intermediate rubber layer to be between 0.05 mm and 0.5 mm as in Examples 4 to 8.

Finally, in the inner rubber layer containing 40% by weight of EPDM with respect to the total amount of the halogenated butyl rubber, the iodine value of EPDM and the vulcanization system were changed.
Brake hoses of the types (Examples 9 and 10 and Comparative Examples 12 to 14) were manufactured, and a physical property test and a metal corrosiveness evaluation test based on JISK 6301 were performed. As the vulcanization system, the following sulfur vulcanization system and peroxide vulcanization system were used.

(1) Sulfur vulcanization compounding recipe (parts by weight) H-IIR 60 EPDM 40 zinc oxide 5 stearic acid 1 FEF carbon 70 paraffin oil 5 sulfur 0.5 vulcanization accelerator CZ 1 vulcanization accelerator TT 1 Vulcanization accelerator D 0.5 (2) Peroxide vulcanization system compounding recipe (parts by weight) H-IIR 60 EPDM 40 Stearic acid 1 FEF carbon 70 Paraffin oil 5 DCP40 2 PEG number 4000 1

The metal corrosiveness was evaluated as follows. First, a JIS K 6301 compression set test sample was sandwiched between two galvanized steel plates, 10% compression was applied, and the sample was allowed to stand at 120 ° C. for 168 hours. After taking out
The corrosion state of the rubber contact portion of the steel plate was visually determined.

[0026]

[Table 3] As can be seen from the test results of Table 3, Comparative Example 12 having an iodine value lower than 20 does not have sufficient strength as compared with Examples 9 and 10 having an iodine value higher than 20. Further, Comparative Example 13 using peroxide vulcanization has a remarkably small compression set, but has problems in strength and corrosiveness. In contrast, EP
As the DM, grades having an iodine value of 20 or more were used, and the sulfur vulcanizing examples 9 and 10 had high strength and good metal corrosiveness.

[0027]

As described above, the brake hose of the present invention uses the hygroscopic hose constituent material and the hygroscopic fluid substance in the hose, and has a high temperature, high humidity, corrosive atmosphere, etc. The amount of water permeation into the hose is extremely small even under long-term conditions, and as a result, it is possible to completely prevent the composite deterioration that occurs when the hygroscopic hose constituent material, the hygroscopic fluid substance in the hose, water, etc. overlap. With this, pressure resistance,
Fatigue resistance and high reliability can be remarkably improved.
It is industrially useful.

[Brief description of drawings]

FIG. 1 is a perspective sectional view showing an embodiment of the present invention.

[Explanation of symbols]

1 Inner layer rubber 3
Outer rubber layer 21 First fiber reinforcing layer 22
Intermediate rubber layer 23 Second fiber reinforcing layer

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[Procedure amendment]

[Submission date] July 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

[0005]

However, although the conventional brake hose having such a structure exhibits excellent pressure resistance, fatigue resistance, and high reliability under normal use conditions, it cannot be used under severe temperature conditions. It has been found that a trace amount of water permeates from the outer layer when used for a long period of time under the condition of high humidity and corrosive atmosphere. The water that has penetrated into the hose is
Not only to lower the boiling point, but also to combine with boric acid ester added to the brake fluid, hose constituent materials,
For example, there is a concern that the fiber reinforcing layer may be compositely deteriorated.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoji Kobayashi 3-1, 1-1 Sukegawa-cho, Hitachi City, Ibaraki Hitachi Cable Company, Ltd. (72) Inventor Hideki Horikoshi 3-1-1, Sukegawa-cho, Hitachi City, Ibaraki No. 1 in the electric wire factory of Hitachi Cable, Ltd.

Claims (4)

[Claims] 1. A brake hose in which a first fiber reinforcing layer, an intermediate rubber layer, a second fiber reinforcing layer, and an outer layer rubber are sequentially provided on the outer circumference of the inner layer rubber, wherein the inner layer rubber is halogenated butyl rubber and ethylene. Including propylene diene rubber (hereinafter referred to as EPDM),
The EPDM is 30 to 70% by weight based on the total amount of the halogenated butyl rubber and the brake hose. 2. The intermediate rubber layer has a thickness of 0.05-0.
The brake hose according to claim 1, wherein the permeability coefficient of the brake fluid or water at 5 mm and 40 ° C is 0.5 to 10 times that of the inner rubber layer and 5 times or less that of the outer rubber layer. 3. The brake hose of claim 1, wherein the EPDM has an iodine value of 20 or more. 4. The halogenated butyl rubber and the E
The brake hose according to claim 1, wherein the PDM is sulfur vulcanized.