JPH04277378A - Slidable seal part - Google Patents

Abstract

PURPOSE:To provide a slidable seal part of which adhesion phenomenon against the sliding face of a sliding lip is hardly generated and increase of sliding resistance is small even at increasing load in the perpendicular direction to the sliding direction. CONSTITUTION:In a slidable seal part provided with a sliding lip part 1a and a seal projecting part 1b, it is featured that at least the sliding lip part is formed out of a rubber compound combined with other subsidiary materials and lubricant in rubber component.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding seal component having a sliding lip portion and a seal convex portion. Here, the sliding seal parts include seal parts that require sliding performance as well as sealing performance, such as dust boots, piston cups, O-rings, protectors, and the like.

[0002] In the following explanation, the compounding unit is a weight unit unless otherwise specified. Moreover, "PHR" is the amount of the auxiliary material mixed with respect to 100 parts of the polymer component (rubber component).

0003

2. Description of the Related Art Here, explanation will be given by taking as an example a dust boot used in a pad-type disc brake as shown in FIG. 1, but the invention is not limited to this.

[0004] The dust boot includes a sliding ring portion 1;
It is composed of a fixed ring part 3 and a bellows part 5 that connects both ring parts 1 and 3. The sliding ring portion 1 is fitted into the inner circumferential groove 7a of the hole of the caliper 7, and the fixed ring portion 3 is fitted into the outer circumferential annular groove 9a of the sliding pin 9. The sliding ring portion 1 has a sliding rib portion 1a on the inner peripheral surface.
A compression type seal protrusion, that is, a seal lip portion 1b is formed on the outer surface.

In the dust boot configured as described above, in order to maintain the sealing performance of the outer circumferential seal lip portion 1b, the sliding ring portion 1 is radially connected to the bottom surface of the inner circumferential annular groove of the caliper 7 and the sliding pin 9. It is necessary to apply a compressive action between the outer peripheral surface of the

[0006]

[Problems to be Solved by the Invention] However, in order to improve the sealing performance of the outer circumferential seal lip portion 1b, if the compression allowance (tightening allowance) of the seal lip portion 1b is increased, the sliding lip portion 1a will be relatively damaged. The pressing load on the sliding pin 9 also increases, and there is a risk that the sliding lip portion 1a may stick to the sliding pin, and the sliding resistance increases. That is, the improvement of the sealing performance of the seal lip portion 1b, the prevention of adhesion of the sliding lip portion 1a to the pin, and the reduction of sliding resistance were in a trade-off relationship.

[0007] In view of the above, the present invention makes it difficult for the sliding lip to stick to the sliding surface even when the load in the direction perpendicular to the sliding direction increases, and to reduce the sliding resistance. The aim is to provide a slidable sealing part that is also small in size.

[0008]

[Means for Solving the Problems] The present invention solves the above problems with the following configuration.

[0009] In the sliding seal component including a sliding lip portion and a seal convex portion, at least the sliding lip portion is formed of a rubber compound containing a rubber component and a lubricant together with other auxiliary materials. It is characterized by

0010

[Detailed explanation of means]

(1) The sliding seal component of the present invention has a sliding lip portion 1
A and the seal convex portion 1b are provided as a prerequisite. Here, the seal convex portion, that is, the seal lip portion 1b is of a compression type, but may be of a bend type.

(2) The sliding seal component of the present invention is characterized in that at least the sliding lip portion is formed of a rubber compound containing a rubber component, other auxiliary materials, and a lubricant.

■Here, the rubber component is not particularly limited as long as it is a rubber commonly used for seal parts, and may include ethylene propylene rubber (hereinafter abbreviated as "EPR"), nitrile rubber, butyl rubber, styrene-butadiene rubber, etc. Select from blended rubbers according to the required performance of each seal component. For example, in the case of the dust boots, EPR, which has excellent weather resistance, heat resistance, aging resistance, ozone resistance, etc., is desirable.

■ The EPR mentioned above includes a binary copolymer of ethylene and α-olefin (usually propylene), abbreviated as EPM, and a copolymer of ethylene, α-olefin, and a crosslinking diene (such as ethylidene norbornene). Both terpolymers abbreviated as EPDM are included. Usually, EPDM is used because of its good workability.

(2) The vulcanization system for the rubber compound is arbitrary, such as a sulfur vulcanization system or a peroxide vulcanization system. From the viewpoint of wear resistance, sulfur vulcanization systems are preferred, and from the viewpoints of resistance to setting (compression set resistance), compression set resistance, etc., peroxide vulcanization systems are preferred.

[0015] Other auxiliary materials include zinc white, stearic acid, carbon black, calcium carbonate, vulcanization accelerator, vulcanizing agent, and
There are process oils, etc.

The use of stearic acid is not essential since the lubricant described below also functions as stearic acid.

(2) Another aspect of the present invention is that the lubricant is entirely or mainly composed of a higher fatty acid amide having 12 to 20 carbon atoms, and the blending amount of the higher fatty acid amide is 0.5 to 10.
phr is a characteristic constituent requirement.

[0018] If the number of carbon atoms is less than 12, sufficient lubricant action cannot be exerted, and if the number of carbon atoms is more than 20, the dispersibility in the rubber compound decreases, and the initial physical properties are adversely affected. Furthermore, examples of fatty acids corresponding to the higher fatty acid amide include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. Among these, oleic acid amide is particularly desirable.

■ The blending amount of the higher fatty acid amide is 0.
If it is less than 5 phr, it is difficult to achieve the effect of reducing sliding resistance, which is the effect of the present invention, and even if it exceeds 10 phr, the effect of reducing sliding resistance does not increase any further, and the dispersibility of the higher fatty acid amide is also poor. Become.

[0020] Furthermore, the higher fatty acid amide may be combined with other lubricants. As other lubricants, one or more types can be selected from silicone-based, fatty acid-based, metal soap-based, hydrocarbon-based, ester-based, etc. The amount of other lubricants is 0.5-9 ph
The total amount of r, sushi and lubricant shall not exceed 10 phr.

Examples of each of the above-mentioned lubricants are shown below. Silicone-based...Silicone oil, silicone resin powder, etc.

[0022] Fatty acid type: stearic acid, palmitic acid,
Oleic acid etc. Metallic soaps...Metal salts of stearic acid such as lead, cadmium, barium, calcium, and zinc.

Hydrocarbons: liquid paraffin, natural paraffin, polyethylene wax, etc. Ester type...butyl stearate, cetyl palmitate, stearic acid monoglyceride, etc.

(3) The slidable seal part of the present invention is produced by mixing and kneading a rubber component with a lubricant that satisfies the above requirements together with the above auxiliary materials using a transfer/injection molding machine. , dust boots, piston cups, and other sliding seal parts. At this time, only the sliding lip portion may contain the lubricant.

The dust boot shown in FIG. 2 is an improved product of FIG. 1, in which the seal lip portion is formed on the outer end surface of the sliding ring portion 1A, and a metal insert 4 having an L-shaped cross section is provided. is integrated into the outer periphery of the sliding ring portion 1. In this configuration, the seal lip portion 1
Since the pressure contact direction of the sliding lip portion 1a and c are perpendicular to each other, Fig. 1
The pressure force as large as in is not applied to the sliding lip portion. However, in order to reduce sliding resistance, it is desirable to apply the present invention.

[0026]

[Operations and Effects of the Invention] Due to the above-described structure, the slidable seal part of the present invention has a lower sliding effect at the sliding part than a seal part that does not contain a lubricant, as shown in the test examples described later. Resistance is significantly reduced. This is particularly noticeable when the lubricant is a higher fatty acid amide. Therefore, even if the load in the direction perpendicular to the sliding direction increases, it is difficult for the sliding lip to stick to the sliding surface, and the sliding resistance increases little. It becomes possible. In addition, when the present invention is applied to a piston cup, when the rigidity and compression allowance of the rubber part are increased to ensure sealing performance, the frictional noise that occurs when the piston slides, so-called "squeal", is reduced. It can also be prevented from occurring.

The reason for these effects is presumed to be that the lubricant in the rubber bleeds out, forming a lubricating thin film at the interface of the sliding part.

[0028]

[Test Examples] Test examples conducted to confirm the effects of the present invention will be explained below.

(1) Based on the following formulation, the lubricant of the type shown in Table 1 was blended with EPDM along with other auxiliary materials, and the rubber material after kneading was press-vulcanized (conditions: 170
℃ x 15 minutes), a sheet of 2 mmt was obtained.

Example/Comparative Example EP
R compounding prescription EPDM rubber *1)
100 parts zinc white
5
Part FEF black
50 copies
Pros oil tel (paraffin type)
20 parts co-crosslinking agent

5 parts organic peroxide

Part 5 Lubricant

Variable *1) “EPT3
045'' Manufactured by Mitsui Petrochemicals Co., Ltd. On each rubber sheet prepared in this way, a hemispherical bowl-shaped glass slider (radius: 3 cm) with a 200 g weight placed on it was placed 20 cm on the rubber sheet.
m sliding (pulling speed 20 cm/min), the load reading of the load cell at that time, the beginning of sliding, and the average value at the time of sliding were used as static and dynamic sliding resistance, respectively.

The results are shown in Table 1, and it can be seen that Examples 1 to 5, which meet the structural requirements of the present invention, have lower sliding resistance than Comparative Examples that do not contain a lubricant in the rubber compound. I understand. In particular, Examples 1 to 3 containing higher fatty acid amides
has significantly reduced sliding resistance.

[0032] Also, regarding each rubber material, JIS K
6301, normal physical properties, heat resistance (heat aging conditions: 120°C x 70h air heating), and compression set (heat treatment time: 120°C x 22h) were also measured, and the results are also shown in Table 1. From the results in Table 1, the examples of the present invention are as follows:
It can be seen that there is almost no difference in physical properties such as normal physical properties. The meanings of the symbols in the table are as follows.

[0033] Normal physical properties...HS (JIS A): hardness,
TB: tensile strength, EB: elongation at break, M100:
Tensile stress at 100% elongation.

Heat resistance...△HS: Change in hardness, △TB
: Rate of change in tensile strength, △EB: Rate of change in elongation at break.

Compression set: CS: Compression set rate.

[0036]

[Table 1]

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of a dust boot which is an application example of the slidable seal component of the present invention.

FIG. 2 is a half-sectional view of a dust boot that is also an improved version of FIG. 1;

[Explanation of symbols]

1, 1A...Sliding ring part, 1a...Sliding lip part, 1b, 1c...Seal lip part (seal convex part), 3, 3A
...Fixing ring part, 5, 5A... Bellows part, 7... Caliper, 9... Sliding pin.

Claims (5)

[Claims] Claim 1: A sliding seal component comprising a sliding lip portion and a seal convex portion, wherein at least the sliding lip portion is formed of a rubber compound containing a rubber component and a lubricant together with other auxiliary materials. A sliding seal component characterized by: 2. In claim 1, the rubber component is ethylene propylene rubber, and the lubricant is entirely or mainly composed of a higher fatty acid amide having 12 to 20 carbon atoms, and the blending amount of the higher fatty acid amide is 0.5~10ph
A slidable seal component characterized in that: r. 3. In claim 2, the lubricant to be combined with the higher fatty acid amide is selected from among silicone-based, fatty acid-based, metal soap-based, hydrocarbon-based, and ester-based,
A sliding seal component characterized in that one or more types are selected. 4. The sliding seal component according to claim 2, wherein the higher fatty acid amide is oleic acid amide. 5. The sliding seal component according to claim 3, wherein the silicone-based lubricant is silicone oil.