JP4313458B2 - Friction material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a friction material suitable as a brake member material, such as a clutch facing material and a brake material, used in a braking device for automobiles, aircraft, railway vehicles, and industrial equipment.
[0002]
[Prior art and problems to be solved by the invention]
As a friction material for a braking member, a friction material obtained by dispersing and binding asbestos in an organic or inorganic binder has been used so far. However, since this product has insufficient friction and wear characteristics such as heat resistance, and asbestos has environmental health problems such as carcinogenicity, there is a strong demand for the development of alternative products.
[0003]
In response to such demands, friction materials using potassium titanate fibers as base fibers or friction modifiers have been proposed. Potassium titanate fibers do not have carcinogenic properties like asbestos, have excellent heat resistance, and have excellent characteristics that they are effective in preventing fade phenomenon and improving the thermal stability of friction characteristics.
[0004]
However, even with friction materials containing potassium titanate fibers, the current situation is that the solution to the problem of the “squeal” of the braking device is not adequately addressed.
Moreover, since the potassium titanate fiber has a fiber shape, it is bulky, inferior in fluidity, and has a problem that it adheres to the wall of the supply channel at the time of manufacture and closes it.
[0005]
An object of the present invention is to eliminate the above-mentioned conventional problems, and to provide a friction material having excellent friction and wear characteristics and excellent productivity.
[0006]
[Means for Solving the Problems]
The friction material of the present invention is characterized by containing layered and plate-like potassium potassium titanate as a friction modifier.
[0007]
The layered and plate-like potassium titanate 8 used as a friction modifier in the present invention has friction and wear characteristics that are stable against temperature changes, and is suitable as a friction modifier for friction materials. And since it does not have a fiber shape like a potassium titanate fiber, there is little possibility that a supply path will be obstruct | occluded in a manufacturing process, and also worsening of the working environment by an inhalable fiber will not arise.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As the shape of the layered / plate-like potassium titanate used in the present invention, those having a major axis of 10 to 500 μm and a minor axis (thickness) of 50 to 1000 nm are particularly preferably used from the viewpoint of improving frictional wear characteristics.
[0009]
Moreover, it is preferable that 3-50 weight% of layered and plate-shaped 8 potassium titanate is mix | blended in the friction material of this invention. If 3% by weight or more is not blended, the effect of improving the friction and wear characteristics may not be manifested. Even if it exceeds 50% by weight, no further improvement in the friction and wear characteristics can be expected. May be disadvantageous.
[0010]
Although it does not restrict | limit especially as a synthesis | combining method of the layered and plate-shaped potassium 8 titanate used as a friction modifier by this invention, For example, it can manufacture with the following method.
[0011]
_{K x Li y Ti 2-y} O 4 ( where, x is 0.5 to 1.0, y denotes a number of 0.25 to 1.0.) Layered-plate titanate represented by Prepare salt first. In this layered / plate-like titanate, a flux raw material powder mixed so that each element has a desired molar ratio (x and y above) is heated at a temperature of 1100 to 1200 ° C., for example, and then removed. The crystal can be grown by cooling, and the resulting product can be produced by heating and humidifying with water and removing the flux. The K _x Li _y Ti layered-plate titanate represented by _2-y O _4, acid treatment with hydrochloric acid or the like or other mineral acids and organic acids, and the layered-plate titanate. The obtained layered / plate-like titanic acid is dispersed in a saturated aqueous KOH solution and stirred, for example, for about 30 minutes to 5 hours. After separating by filtration, layered and plate-like potassium titanate 8 can be obtained by firing. In general, the firing is preferably performed at a temperature of about 450 to 700 ° C., and the firing time is preferably about 1 to 5 hours.
[0012]
As a specific example of the friction material of the present invention, for example, a friction material comprising a base fiber, a friction adjusting material, and a binder can be exemplified. As a blending ratio of each component in the friction material, 1 to 60 parts by weight of a base fiber, a friction modifier is 20 to 80 parts by weight including a layered / plate-like potassium titanate, 10 to 40 parts by weight of a binder, Examples of other components include 0 to 60 parts by weight.
[0013]
Examples of the base fiber include resin fibers such as aramid fibers, metal fibers such as steel fibers and brass fibers, carbon fibers, glass fibers, ceramic fibers, rock wool, and wood pulp. These substrate fibers are treated with a surface treatment such as aminosilane, epoxysilane or vinylsilane, silane coupling agents, titanate coupling agents or phosphate esters to improve dispersibility and adhesion to the binder. May be used.
[0014]
As the friction modifier in the friction material of the present invention, in addition to the layered / plate-like potassium potassium titanate, other friction modifiers may be used in combination as long as the effects of the present invention are not impaired. For example, organic powder such as vulcanized or unvulcanized natural, synthetic rubber powder, cashew resin powder, resin dust, rubber dust, carbon black, graphite powder, molybdenum disulfide, barium sulfate, calcium carbonate, clay, mica, talc, Diatomaceous earth, Antigolite, Sepiolite, Montmorillonite, Zeolite, Sodium trititanate, Sodium pentatitanate, Potassium titanate, Potassium titanate, and other inorganic powders, Metal powders such as copper, aluminum, zinc and iron, Alumina And oxide powders such as silica, chromium oxide, titanium oxide, and iron oxide.
[0015]
As binders, thermosetting resins such as phenol resin, formaldehyde resin, melamine resin, epoxy resin, acrylic resin, aromatic polyester resin, urea resin, natural rubber, nitrile rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, Thermoplastics such as polyisoprene rubber, acrylic rubber, high styrene rubber, elastomers such as styrene propylene diene copolymer, polyamide resin, polyphenylene sulfide resin, polyether resin, polyimide resin, polyether ether ketone resin, thermoplastic liquid crystal polyester resin Examples thereof include organic binders such as resins and inorganic binders such as alumina sol, silica sol, and silicone resin.
[0016]
In addition to the above components, the friction material of the present invention may contain components such as a rust inhibitor, a lubricant, and an abrasive as necessary.
There is no restriction | limiting in particular in the case of manufacture of the friction material of this invention, According to the manufacturing method of a conventionally well-known friction material, it can manufacture suitably.
[0017]
If an example of the manufacturing method of the friction material of this invention is given, a base material fiber will be disperse | distributed in binder, and it mix | blends combining a friction modifier and the other component mix | blended as needed, and mixes a friction material composition. An example is a method of preparing and then injecting the composition into a mold and pressurizing and heating to form a binder.
[0018]
As another example, the binder is melt-kneaded in a twin screw extruder, compounded from the side hopper in combination with the base fiber, the friction modifier and other components blended as necessary, and extruded. An example is a method of machining into a desired shape after molding.
[0019]
As another example, after the friction material composition is dispersed in water or the like and made on a paper making net, dehydrated and made into a sheet, it is heated and pressed with a press machine to form a binder, An example is a method of appropriately cutting and polishing the obtained friction material to obtain a desired shape.
[0020]
【Example】
The following examples further illustrate the present invention.
Reference Example K _0.8 Li _0.2 Ti _1.8 O _{4 The} layered / plate-like titanate was acid-treated in hydrochloric acid to form a layered / plate-like titanate, which was then dispersed in a saturated aqueous KOH solution. Stir for hours. After separation by filtration, the mixture was baked at 600 ° C. for 2 hours to obtain layered and plate-like potassium potassium titanate.
[0021]
Examples 20 parts by weight of layered and plate-like potassium titanate (major axis 50-60 [mu] m, minor axis (thickness) 0.3 [mu] m, aspect ratio about 180-200) obtained in Reference Example, aramid fiber (product) The name “Kevlar pulp”, average length 3 mm, manufactured by Toray Industries, Inc.) 10 parts by weight, binder (phenolic resin) 20 parts by weight, barium sulfate 50 parts by weight, a raw material mixture, applied pressure 300 kgf / cm ² , normal temperature, After pre-molding for 1 minute, binder molding (pressing force 150 kgf / cm ² , temperature 170 ° C., time 5 minutes) was performed using a mold, and after molding, heat treatment (held at 180 ° C. for 3 hours) was performed. After removal from the mold, polishing was performed to obtain a test disk pad A (JIS D 4411 test piece).
The fluidity of the friction modifier was good, and the raw material mixture was easy to prepare.
[0022]
【The invention's effect】
The friction material of the present invention has an excellent and stable friction coefficient and wear resistance over a wide temperature range from low temperature to high temperature. Therefore, by using it as a brake member material used in automobiles, railway vehicles, aircraft, various industrial equipment, etc., for example, a clutch facing material and a brake material such as a brake lining and a disk pad, the braking function is improved. Stabilization and service life improvement effect can be obtained.
[0023]
The friction material of this invention has the following effects by containing layered and plate-like potassium potassium titanate as a friction modifier.
1) Since the friction modifier has a flat layered structure, stable friction and wear characteristics can be obtained.
2) Since the aspect ratio of the friction modifier is large, it contributes to improving the strength of the friction material itself.
3) The fluidity of the friction modifier is high and the adjustment of the raw material mixture is easy.
4) Very little inhalable dust is generated and the work environment can be kept clean.
5) High heat resistance and stable friction coefficient in a wide temperature range from low to high.

Claims (3)

A friction material comprising a layered / plate-shaped potassium potassium titanate having a major axis of 10 to 500 μm and a thickness of 50 to 1000 nm as a friction modifier.   The friction material according to claim 1, comprising 3 to 50% by weight of layered and plate-like potassium potassium titanate. Layered and plate-like potassium potassium titanate is K _x Li _y Ti _2-y O ₄ (Wherein x represents a number of 0.5 to 1.0 and y represents a number of 0.25 to 1.0, respectively). The friction material according to claim 1 or 2, which is obtained by dispersing plate-like titanic acid in a saturated KOH aqueous solution.