JPS62141326A - Friction material - Google Patents

Abstract

PURPOSE:To prevent sticking of iron and a friction material by providing a void between iron and a metal which can be a sacrifice anode for iron to prevent the generation of rust even if dew condensation is caused in the void. CONSTITUTION:5mg/cm<2>-30mg/cm<2> of metal which can be a sacrifice anode for iron is stuck to the surface of a friction material, and a groove or a hole is provided in a layer of the metal which can be a sacrifice anode for iron. That is, after metal which can be a sacrifice anode is stuck to the friction surface, a device like a frog having a lot of needle-like projections is forced in the friction surface to make holes. Accordingly, a void is formed between iron and the metal which can be a sacrifice anode for iron, so that even if dew condensation is caused in the void, rust will not be generated to prevent sticking of iron and the friction material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to friction materials such as clutch facings and brake linings used in power transmission of automobiles.

(Conventional technology and its problems) Friction materials, especially clutch facings, have excellent friction properties (stable single-frequency coefficient), wear resistance9 mechanical properties (high berth strength),
It is required to have excellent shudder resistance and adhesion resistance.

Recently, among the above properties, sticking resistance has become an important characteristic item.

In most cases, friction materials contain a small amount of salt, and this salt promotes rusting of the mating material, iron. In particular, salt containing chlorine ions (CJ-) and sulfate radicals (804"-) significantly accelerates the rusting of iron. If industrial machinery, automobiles, etc. that use friction materials are left in storage for a long period of time, ,
Rust may occur between the iron and the friction material, causing the two to stick together. In areas with large temperature differences, dew condensation tends to form between the steel and the friction material, and this condensation causes rust between the steel and the friction material, causing the problems described above. . A way to solve this problem is to use sodium nitrite, phosphoric acid, and phosphates in the friction material composition.

JP-A No. 58, 1983, containing rust preventive agents such as boric acid and borate.
As disclosed in Japanese Patent No. 81238, there is a method of thermally spraying a metal that can be used as an iron sacrificial anode onto the surface of a friction material.

However, the former rust prevention method requires high relative humidity.

This method is effective when the friction material absorbs a large amount of moisture, but under conditions where the friction material absorbs moisture and dries at the same time, the anti-rust agent becomes unevenly distributed and cannot be sufficiently effective.

The climate in areas where rusting actually occurs is low temperature and high humidity at night, but high temperature and low humidity during the day, which causes the friction material to absorb moisture and dry out. The latter rust prevention method.

Although it is more effective than adding rust inhibitors, especially when the amount of metal deposited that can serve as a sacrificial anode for iron is small, 5 mg/
If it is less than cm'2, the rust prevention effect cannot be maintained for a long period of time. Furthermore, if there is a large amount of metal that can be used as a sacrificial iron anode attached, it becomes difficult for the salt (electrolyte) necessary for sacrificial anode action to be eluted from the friction material.

For this reason, a portion, that is, a void, is likely to be formed where the iron and the metal that can be used as the sacrificial anode do not come into close contact with each other, and when dew condensation occurs in this void, the anticorrosive effect of the sacrificial anode becomes insufficient.

The object of the present invention is to provide a friction material that does not suffer from the above-mentioned drawbacks.

(Means for Solving the Problems) As a result of various studies regarding the above-mentioned drawbacks, the present inventors found that 5 mg/g of metal that can serve as a sacrificial iron anode was added to the surface of the friction material.
cm' ~ 30 mg/cm'' and provided grooves and/or holes in the layer of metal that can be used as a sacrificial anode for iron, a void is created between the iron (the other material) and the metal that can be used as a sacrificial anode for iron. It was confirmed that rust did not occur even if dew condensed in the gap, and the problems caused by the adhesion of iron and friction material were resolved.

In the present invention, a metal capable of forming an iron sacrificial anode is deposited on the surface of a friction material at a thickness of 5 mg/cm' to 30 mg/cm', and grooves and/or holes are provided in the metal layer capable of forming an iron sacrificial anode. Regarding friction materials.

In the present invention, a metal that can serve as a sacrificial anode for iron refers to a metal that, when coexisting with iron in the electrochemical mechanism of rust, serves as an anode instead of iron and prevents iron from rusting. For example, zinc, aluminum, magnesium, etc.
These metals may be used alone or in a mixture of two or more without any particular limitation.

In addition, these metals may be attached to the surface of the iron and/or friction material by thermal spraying in the form of wires or powders. From the viewpoint of friction material properties, it is preferable to thermally spray the binder onto the surface of the friction material.

The iron sacrificial anode is a metal that can be used in an amount of 5mg on the surface of the friction material.
/cm' to 30mg/cm" preferably 10mg/cm
It is necessary to deposit up to 25 mg/cm. If it is less than 5 mg/cm, the rust prevention effect cannot be maintained for a long time, and if it exceeds 30 mg/cm, the performance as a friction material will deteriorate. In particular, there are disadvantages such as a decrease in the initial coefficient of friction.Moreover, excessive adhesion may lead to increased costs.

The hole in the metal layer, which can be used as a sacrificial iron anode, has a diameter of 3 m.
It is preferably less than m, and more preferably less than 1+um. Further, the width of the groove is preferably 3 mm or less, more preferably 1 mm or less. Note that there is no particular restriction on the number of grooves and/or holes.

There are no particular restrictions on the method of forming the holes or grooves.

For example, in the case of clutch facings, brake linings, etc., after attaching a metal that can be used as a sacrificial anode to the friction surface, holes can be made by pushing a tool like a sword pin with many needle-like protrusions into the friction surface. . Alternatively, the grooves may be formed using a sharp knife. Alternatively, holes or gaps may be provided in the metal foil in advance and then the metal foil may be pressed against the friction surface. Furthermore, irregularities such as grooves may be formed on the surface of the friction material, and then a metal that can be used as a sacrificial anode may be deposited by thermal spraying.

Grooves and/or holes are indispensable for effective sacrificial anode action. Without grooves and/or holes, the salt necessary for sacrificial anode action will not be leached from the friction material. A void is likely to be formed between the material and the metal that can serve as the anode, and when dew condensation occurs within this void, the anticorrosive effect of the sacrificial anode becomes insufficient.

In order to make the sacrificial anode effect more effective, it is desirable that the friction material contains such salt that when it absorbs moisture, the friction material has a concentration of about 0.01 to 1.0% by weight.

(Example) The present invention will be explained below with reference to Examples.

Example 1 Class 4 asbestos (manufactured by Jones Manpuill)
85 parts by weight and 15 parts by weight of Sufu were uniformly mixed, and then processed into a carding machine to form an asbestos web. 82 parts by weight of this asbestos web was mixed with wear-resistant powder of thermoset cashew shell oil (manufactured by Tohoku Kako, trade name: FF1800). ) was dispersed in an amount of 18 parts by weight, and applied to a condenser to obtain an asbestos sliver containing abrasion-resistant powder, which was further twisted using a spinning machine to form a single yarn with a diameter of 1 ff [m]. Next, two of these single yarns and one brass wire having a diameter of 0.16 mm were twisted together to form a wear-resistant powder-containing diasbestos yarn of 2.56/m.

This abrasion-resistant powder-containing diasbest yarn is coated with melamine-modified phenol resin (manufactured by Dainippon Ink).
A coated yarn was obtained by impregnating and adhering the yarn to a concentration of 0.00% by weight.

Next, the coated yarn was unevenly formed into a tablet in the shape of a clutch facing, and this was heated to 150±5°C.

Heat and pressure molding was performed for 8 minutes at a pressure of 300 kg/cm''.

Thereafter, the surface was polished, and after heat treatment at 200° C. for 8 hours, the surface was further polished to obtain a clutch facing in the shape specified in the drawing.

Next, a zinc wire with a purity of 95% was melted using a thermal spraying machine manufactured by Kato Metallicon Industries, trade name KR,-5, and the clutch facing obtained above was melted under the conditions of a voltage of 15 V, a current of 20 A, and an air pressure of 5 kg/cm. 10 mg/cm'' of zinc was thermally sprayed onto the surface. After this, the diameter is 0.5 at intervals of 5 barrels.
An instrument with an ann needle was pushed into the clutch facing to create a hole in the thin layer of zinc.

Next, the clutch facing, which had holes in the zinc thin film layer, was pressed against the mating material, gray cast iron (JIS G5011), with a surface pressure of 2 kg/cm', and rusting and sticking force tests were conducted under the conditions shown in Table 1. .

The results are shown in Table 1. The following Examples and Comparative Examples were also tested for rust development and adhesion strength in the same manner.

Note that the clutch facing obtained in Example 1 contained 0.3
Salinity in weight% (Ca”, Na”, Mo”, C
l-, SO4''-, etc.).

Example 2 75 parts by weight of class asbestos (manufactured by Carey) and 25 parts by weight of Sufu were uniformly mixed with No. 4, and then an asbestos web was made using a carding machine. 85 parts by weight of this asbestos web was heat-cured with cashew shell oil. After dispersing 18 parts by weight of abrasion-resistant powder (manufactured by Tohoku Kako, trade name: FF1800), the mixture was poured into a condenser to obtain an asbestos sliver containing abrasion-resistant powder. The following steps are similar to those in Example 1 and Example 1
A clutch facing was obtained using a similar material.

Next, Example 1 was applied to the surface of the clutch facing obtained above.
Zinc was thermally sprayed at 20 cm/cm' in the same manner as above. Thereafter, a clutch facing with holes provided in the zinc thin film layer was obtained in the same manner as in Example 1. Note that the clutch facing obtained in Example 2 contained 0.1% by weight of salt.

91 Example 3 Cutting grooves measuring 1 mm x 5 mm were provided in a zinc foil having a thickness of 30 μm (21.5 mg/cm 11 ) at 7.5 mm intervals. Next, this was pressed onto the surface of the clutch facing obtained in Example 1 under conditions of a pressure of 100 kg/cm'' and a temperature of 150±5° C. to obtain a clutch facing with grooves formed in the zinc foil.

Comparative Example 1 4 mg/ml was applied to the surface of the clutch facing obtained in Example 1.
cm' of zinc was deposited by thermal spraying, and otherwise the same method as in Example 1 was used to obtain a clutch facing in which holes were formed in the zinc thin film layer.

Comparative Example 2 33 m on the surface of the clutch facing obtained in Example 2
A clutch facing was prepared by thermally spraying and depositing zinc at a concentration of g/cm', but otherwise using the same method as in Example 2, with holes formed in the zinc thin film layer.

Comparative Example 3 12mg was applied to the surface of the clutch facing obtained in Example 1.
/cm'' of zinc was deposited by thermal spraying. However, no holes, grooves, etc. were provided in the thin zinc film layer.

*The test was carried out in a 24-hour cycle, alternating between a factory temperature of 6°C and a humidity of 92°C and a temperature of 44°C and a humidity of 40°C.

*2 Recovery of friction coefficient was slow compared to other examples and comparative examples. In addition, the shudder resistance also deteriorated.

*3 The clutch facing obtained in Example 1 is not subjected to anti-rust treatment.

*4 Brake lining without anti-rust treatment.

(Effects of the Invention) The friction material of the present invention maintains its anti-corrosion effect for a long period of time even under high temperature and high humidity environments, environments where moisture absorption and dryness are repeated, and it also maintains its anti-corrosion effect for a long period of time even in environments where moisture absorption and dryness are repeated. It is extremely effective industrially.

Claims (1)

[Claims] 1. 5 m of metal that can be used as an iron sacrificial anode is placed on the surface of the friction material.
A friction material formed by providing grooves and/or holes in a metal layer to which g/cm^2 to 30 mg/cm^2 is deposited and which can serve as a sacrificial iron anode. 2. The friction material according to claim 1, wherein the friction material is a clutch facing.