JP2000034468A - Wet friction material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wet friction material which exhibits excellent resistance to heat and wear and excellent noise properties even in the use under a high load and thus retains a stable and high coefficient of friction by adding a hard porous carbon material to a wet friction material mainly comprising a fibrous substrate, a filler, and a friction modifier. SOLUTION: Pref., a carbon material has a carbon content of 60-100 wt.%, a Vickers hardness of 200 Hv or higher or a compression strength of 400 kgf/cm2 or higher, a porosity of 15-50%, and a particle size of 10-200 μm. Such a carbon material can be prepd, by carbonizing, baking, and vitrifying a material contg, an org, resin at 300-1,500 deg.C, Pref., the friction material contains 1-30 wt.% hard porous carbon material, 20-80 wt.% fibrous substrate, 10-50 wt.% filler, and 1-10 wt.% friction modifier. Further addition of a thermosetting resin binder is also pref.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an automobile, an industrial machine,
The present invention relates to a wet friction material used for a friction engagement device such as a clutch or a brake used in an agricultural machine or the like immersed in oil.

[0002]

2. Description of the Related Art In a friction engagement device used in oil of an automobile, an industrial machine, an agricultural machine, etc., a plurality of disk plates each having a wet friction material adhered to the surface of a substrate (core metal) usually made of metal. And, a plurality of separate plates as a friction mating member composed of a single plate such as a metal plate are alternately arranged, and in lubricating oil, these plates are pressed against each other and released, and The transmission / cutoff of the driving force or the actuation / release of the braking is performed.

[0003] Conventionally, as a wet friction material using such a friction engagement device used in oil, a paper-based wet friction material called "paper friction material" is generally used. This wet friction material is formed by impregnating a paper binder obtained by forming a base fiber such as pulp or aramid fiber and a friction modifier or filler with a resin binder made of a thermosetting resin, and then heating and curing. It was done.

In such a paper-based wet friction material, as a thermosetting resin impregnated into a paper body as a resin binder, heat resistance, bonding (adhesion) and mechanical strength are enhanced, and friction characteristics and abrasion resistance are improved. Phenolic resins are generally used to maintain properties and the like, and improvements using modified phenolic resins have been made.

However, even when a modified phenolic resin or the like is used as a binder for a papermaking body, the frictional coefficient can be increased, but the molecular bond of the binder is weakened, resulting in a heat resistance. Tends to decrease. For this reason, there has been a problem that the friction coefficient is reduced in a short time when the device is continuously used under a high load condition, and the noise and abrasion resistance are also rapidly reduced.

[0006]

SUMMARY OF THE INVENTION The present invention provides a wet friction material having heat resistance, abrasion resistance, excellent noise characteristics, and maintaining a stable high coefficient of friction even under conditions of high load use. The task is to provide.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above problems can be solved by using hard porous carbon as one component of a friction material, and have completed the present invention.

That is, the present invention relates to a base fiber, a filler,
And a wet friction material containing a friction adjusting material as a main component,
It is a wet friction material characterized by containing hard porous carbon.

The present invention also provides the wet friction material, wherein the content of the hard porous carbon is 1 to 30% by weight based on the total amount of the friction material.

[0010] The present invention also relates to 1 to 30% by weight of hard porous carbon, 20 to 80% by weight of base fiber, 10 to 50% by weight of filler, 1 to 10% by weight of friction modifier, based on the total amount of friction material. % Of the wet friction material.

The wet friction material further comprises a thermosetting resin binder in an amount of 10 to 60% by weight of the whole friction material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[0013] The present invention is a wet friction material mainly comprising a base fiber, a filler and a friction modifier, characterized by containing hard porous carbon.

First, the hard porous carbon will be described. The hard porous carbon used in the friction material of the present invention refers to a hard, porous material containing carbon. The hard porous carbon of the present invention may be composed only of carbon, or may contain a substance other than carbon with carbon as a main component. Here, the content of carbon is 60 to 100% by weight.
Is preferably within the range.

The term "hard" means that the carbon material has a high strength and has a Vickers hardness of 200 Hv or more or a compressive strength of 400 kgf / cm ² or more. The compressive strength is 400 kg to 1000 kgf / c in consideration of the wear resistance of the friction material and the wear resistance of the mating material of the friction material.
m ² range, and Vickers hardness is 200-2000.
It is preferably in the range of Hv.

The term “porous” refers to a state in which a solid has many small voids inside or on the surface. The porosity of the hard porous carbon is preferably in the range of 15 to 50% in consideration of smooth cooling by lubricating oil flow and maintaining the strength of the friction material.
More preferably, it is in the range of 0%. Here, the porosity refers to a percentage of the volume of pores (voids) with respect to the total volume of hard porous carbon.

The particle size of the hard porous carbon is preferably in the range of 10 to 200 μm, more preferably 30 to 12 μm.
Those having a particle size distribution in the range of 0 μm are used.

Specifically, density: 1.25 (g / cm ³ ), coefficient of friction: 0.13, Vickers hardness: 200 to 2000 Hv (average 400 H)
v), compressive strength: 400 to 1000 kgf / cm ² Young's modulus: 3000 MPa, porosity: 15 to 50%.

Such a hard porous carbon is prepared by preparing a carbon material containing an organic resin in a nitrogen atmosphere at 300 ° C. to 1500 ° C.
It can be produced by firing at a temperature of carbonization and then vitrification (JP-A-10-101453).

The base fibers used in the friction material of the present invention include cellulosic fibers such as wood pulp and linter pulp, and aromatic polyamide fibers (aramid fibers and the like; commercially available products manufactured by DuPont, trade name Kevlar, etc.). ), Organic fibers such as novoloid fibers and acrylic fibers, inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, or metal fibers such as whiskers, steel fibers, copper fibers, and brass fibers.

Examples of the filler used in the friction material of the present invention include inorganic oxides such as diatomaceous earth, calcium carbonate, magnesium carbonate, and potassium titanate, and specific examples thereof include hard materials such as alumina, silica, and zirconia. Metal oxide particles of copper, brass, iron, zinc, and the like; layered inorganic substances such as vermiculite and mica; and inorganic compounds such as barium sulfate, calcium carbonate, and magnesium oxide.

The friction modifier used in the friction material of the present invention includes organic friction modifiers such as resin dust (for example, cashew dust and melamine dust) and rubber dust, and solids such as graphite (graphite), molybdenum disulfide, and activated carbon. A lubricant or the like can be used.

In the present specification, the term "friction modifier" is used without including hard porous carbon.

The friction material of the present invention is a wet friction material mainly comprising a base fiber, a filler and a friction modifier.

The content of the hard porous carbon with respect to the total amount of the friction material is preferably 1 to 30% by weight, more preferably 1 to 30% by weight.
20% by weight. When the content of the hard porous carbon is within this range, friction characteristics such as heat resistance, abrasion resistance and noise are good, and a high friction coefficient is obtained.

As the base fiber, one or a combination of two or more of the above base fibers can be used. The content of the base fiber is preferably from 20 to
It is 80% by weight, more preferably 40 to 60% by weight.

As the filler, one of the above-mentioned fillers is used.
Species or a combination of two or more can be used. The content of the filler is preferably 10 to 10% of the total amount of the friction material.
It is 50% by weight, more preferably 15 to 45% by weight.

Further, as the friction adjusting material, one or a combination of two or more of the above friction adjusting materials can be used. The content of the friction modifier is preferably 1 to 10% by weight, more preferably 3 to 8% by weight, based on the total amount of the friction material.

As the binder, a thermosetting resin such as a phenol resin, an epoxy resin, a melamine resin, and a silicone resin, or a modified resin thereof can be suitably used. The thermosetting resin binder has a role of binding the respective components of the friction material, and the amount of the binder used is preferably 10 to 60% by weight, more preferably 20% by weight, based on the total amount of the friction material. ５０50% by weight.

The friction material of the present invention can improve durability such as abrasion resistance and noise while maintaining a high friction coefficient by using hard porous carbon as the friction material. This is because the porosity of the hard porous carbon is high, so that a large number of pores smoothly disperse the generated frictional heat by holding and flowing the lubricating oil (oil cooling effect).
However, it is conceivable to improve noise when using a clutch, a brake or the like including the friction material. In addition, because the porosity is high, cooling by the flow of lubricating oil is smoothed, the load on the friction material is reduced even when used under high load conditions, and durability such as wear resistance is improved. Conceivable. Furthermore, it is considered that the high strength has good durability such as abrasion resistance, and that the hard porous structure appropriately attacks the mating material, so that a high friction coefficient can be maintained.

The wet friction material of the present invention can be used for, for example, automobiles,
It can be used as a frictional engagement device used in oils of industrial machines, agricultural machines, etc., that is, a friction material for a multi-plate clutch or a multi-plate brake used in lubricating oil. Further, it can be suitably used as a friction material of a wet friction engagement device such as a clutch or a brake used in other oils.

The friction material of the present invention is obtained by impregnating a paper binder obtained by forming the above-mentioned hard porous carbon, base fiber, filler and friction modifier with a resin binder made of a thermosetting resin. . Next, the paper body impregnated with the resin binder is appropriately dried, and then heated generally at a temperature of 120 to 250 ° C., whereby the resin binder is cured. The thus obtained friction material is applied to a substrate to which an adhesive has been applied in advance, and
It is used by bonding by heating at a temperature of ° C. Further, the paper body impregnated with the resin binder can be directly hot pressed on the substrate. In this case, curing of the resin binder and adhesion to the substrate are performed simultaneously.

[0033]

Embodiments of the present invention will be described below.

[0034]

Examples 1 to 6, Comparative Examples 1 and 2 (1) Production of Friction Material <Examples 1 to 6> Table 2 shows the types and amounts (% by weight) of raw material components of the friction material used in this example. Is shown. The hard porous carbon used here was made by mixing oil-extracted defatted bran with a phenolic resin and heating and pressing while degassing, then incinerating this molded product The temperature is gradually raised from 250 ° C. to 500 ° C. while flowing nitrogen gas in the furnace, and then carbonized and calcined for 2 hours while maintaining the temperature at 500 ° C., and then the temperature is gradually lowered to vitrify. .

Using a papermaking stock solution in which the types and amounts of materials shown in Table 2 were dispersed, papermaking was performed with a papermaking machine to a thickness of 0.7 mm.
Was obtained. Then, after drying this paper body, it was punched into a ring having an outer diameter of 133 mm and an inner diameter of 113 mm to obtain a ring-shaped paper body. Then, this ring-shaped paper body was impregnated with a phenol resin solution by a dipping method.
Next, the resin was air-dried and then heated at a temperature of 150 ° C. for 10 minutes to cure the resin. The wet friction material thus obtained was superimposed on a substrate to which an adhesive was applied in advance, sandwiched by a jig, and then heated and formed at 230 ° C. for 60 minutes to obtain friction materials of Examples 1 to 6. Examples 1 to 6
Of the friction material, that is, the proportion of the phenol resin in the entire friction material after the heat molding was 30% by weight.

In Examples 1 to 5, friction materials were manufactured with the amount of hard porous carbon added being 1, 5, 10, 20, and 30% by weight based on the total amount of the friction materials.

In Example 6, a friction material was produced by replacing a part of the aramid fiber of Example 2 with natural pulp fiber.

<Comparative Examples 1 and 2> For comparison with the friction materials of Examples 1 to 6, hard porous carbon was replaced with artificial graphite (porosity of 5 to 10%) used as a solid lubricant, or Activated carbon which is typically a porous carbon material (porosity 25 to 35)
%), The friction materials of Comparative Examples 1 and 2 were produced. (2) Evaluation test (friction performance test and measurement of wear amount) Next, the friction materials of Examples 1 to 6 thus produced,
With respect to the friction materials of Comparative Example 1 and Comparative Example 2, an evaluation experiment regarding the friction characteristics and wear resistance was performed.

More specifically, a friction performance test (SAE No. 2) was performed for each friction material under the conditions shown in Table 1.
The coefficient of friction was measured.

Further, the thickness of the friction material after the test was measured, and the wear amount was obtained by subtracting the thickness from the previously measured initial value. Table 2 shows the results.

[0041]

[Table 1] (3) Evaluation of Noise Properties For the friction materials of Examples 1 to 6 and Comparative Examples 1 and 2, SEA No. In the friction performance test according to No. 2, sensory evaluation was performed on the noise generation level to evaluate the noise property. That is, the noise generation level was evaluated on a five-point scale of 1 to 5; one or two points were evaluated as “noise: ◎”; three points were evaluated as “noise:」 ”; Noise: × "
And Table 2 shows the results. It should be noted that, in the present specification, improving the noise property means reducing the noise generation level.

[0042]

[Table 2] (4) Results In Examples 1 to 5, evaluation tests were performed by changing the amount of hard porous carbon added to 1, 5, 10, 20, and 30% by weight based on the total amount of the friction material. Within the range of ２０20% by weight, good results of improving durability while maintaining a high coefficient of friction were obtained.

In Example 6, a part of the aramid fiber of Example 2 was replaced with natural pulp fiber, but the effect was not affected by the type of fiber, and similar good results were obtained.

In Comparative Example 1, artificial graphite (porosity of 5 to 10) was used.
%) Was used in place of the hard porous carbon, but had an effect on noise and abrasion resistance, but could not obtain a high coefficient of friction.

In Comparative Example 2, activated carbon (porosity 25-35)
%) Was used instead of hard porous carbon. In this case, a high friction coefficient can be maintained by the porous structure of activated carbon,
Although effective for noise, wear was remarkably large.

[0046]

According to the wet friction material of the present invention, the hard porous carbon is blended with the friction material, so that even under a high load condition,
It has good friction characteristics such as heat resistance, wear resistance and noise, and can maintain a high friction coefficient.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J058 BA21 BA31 BA41 BA76 FA01 FA11 FA31 GA07 GA20 GA26 GA27 GA28 GA34 GA35 GA45 GA55 GA57 GA58 GA85 GA86 GA88 GA92 GA93 GA94

Claims (4)

[Claims] 1. A wet friction material mainly comprising a base fiber, a filler, and a friction modifier, wherein the wet friction material contains hard porous carbon. 2. The wet friction material according to claim 1, wherein the content of the hard porous carbon is 1 to 30% by weight based on the total amount of the friction material. 3. The composition according to claim 1, comprising 1 to 30% by weight of hard porous carbon, 20 to 80% by weight of base fiber, 10 to 50% by weight of filler, and 1 to 10% by weight of friction modifier. 2. The wet friction material according to 2. 4. The wet friction material according to claim 3, further comprising a thermosetting resin binder in an amount of 10 to 60% by weight of the whole friction material.