JP2878120B2 - Brake pad - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vehicle, brake pads etc. Industrial, lining, or of the friction material to be used as clutch facings and the like, in particular, Burekipa
It relates to head.

[0002]

2. Description of the Related Art A friction material used for a disc brake pad, a drum brake shoe, and the like of an automobile frictionally engages with a disc rotor and a brake drum, which are mating members, and plays an important role of converting kinetic energy into heat energy. I am carrying it. For this reason, the friction material always generates heat and becomes high temperature. Therefore, such a friction material is required to have stable friction characteristics with a small change in friction coefficient even with a temperature change, in addition to heat resistance, wear resistance and the like. Further, it is necessary that the aggressiveness against the opposing member is low and that no judder is generated, and the characteristics required for the friction material cover various items.

Therefore, conventionally, in order to satisfy these various characteristics, the friction material is constituted as a composite material.
That is, the friction material is aramid fiber, a fiber base material that forms a skeleton such as potassium titanate fiber, a resin binder such as a phenol resin that binds and holds the fiber base material, and a matrix of these fibers and the binder. It is generally composed of various fillers that are dispersed and filled. Examples of the filler include fillers such as barium sulfate and calcium carbonate, solid lubricants such as graphite and molybdenum disulfide, cashew dust, metal powder, abrasives such as silica, and other friction adjusting agents. Additives and the like are used.

[0004] The characteristics required of the friction material include:
There is also no unpleasant noise (noise) generated in the brake, that is, no squeal. Moreover, this demand has been increasing in recent years as automobiles have become faster and more sophisticated.

[0005] Means well-known and performed in the past to prevent the occurrence of such squeals are as follows:
To mix rubber dust (rubber powder) as a filler in the friction material. Such an example is described in, for example, JP-A-5-331452, in which a friction material is formed in a two-layer structure, and a large amount of rubber powder is added to the friction material layer on the back metal side. I have.

[0006]

By mixing rubber dust with the friction material, the vibration damping effect of the friction material improves the squeal performance of the friction material, and the noise during braking can be reduced.

However, since rubber dust has low heat resistance, blending it with a friction material tends to deteriorate the fade performance of the friction material, such as a decrease in the friction coefficient μ during fading. Therefore, the above-mentioned Japanese Patent Application Laid-Open No. 5-33145 has been proposed.
In the apparatus disclosed in Japanese Patent Publication No. 2 (1990), the friction material is formed in a two-layer structure, a large amount of rubber dust is added to the friction material layer on the back metal side, and the amount of rubber dust in the friction material layer on the friction surface side is reduced. . However, forming the friction material in a two-layer structure in this way is more troublesome than forming the friction material in a single layer.

Accordingly, an object of the present invention is to provide a brake pad having improved squeal performance without deteriorating fade performance.

[0009]

The friction material of the present invention is a friction material containing a fiber base material, a resin binder, and a filler.
The filler contains cashew-rubber composite dust composed of a composite of a cured component of cashew nut shell liquid and a rubber component.

The cured product of cashew nut shell liquid is composed of the same components as cashew dust, and is obtained by curing cashew nut shell liquid (cashew oil) with an aldehyde such as furfural or formaldehyde or a curing agent such as hexamethylenetetramine. It is. The rubber component of the composite dust is equivalent to rubber dust, and includes nitrile rubber (NBR), styrene / butadiene rubber (SBR), natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), and the like. It consists of a vulcanizate of rubber. Therefore, the cashew / rubber composite dust can be said to be a composite of cashew dust and rubber dust.

The cashew / rubber composite dust composed of a composite of these components can be produced by various methods. One method is, for example, kneading a rubber such as NBR, a vulcanizing agent such as sulfur, and an additive such as carbon black, adding a polymer of cashew nut shell liquid and furfural and the like, and further mixing. This is a method in which the mixture is cured by heating to cause polycondensation, followed by cooling and pulverization. In this case, instead of the rubber kneaded material, a fine powder of rubber dust prepared in advance can be used. Also, make a fine powder of cashew dust in advance,
This can be granulated using a rubber solution containing a vulcanizing agent and additives. Further, instead of this granulation method,
The fine powder of cashew dust and a rubber containing a vulcanizing agent and additives can be kneaded, and the kneaded product can be vulcanized and then pulverized.

In such a cashew / rubber composite dust, a component (hereinafter, simply referred to as a "cashew component") composed of a cured cashew nut shell liquid and a rubber component can be in any ratio. However, in order to sufficiently prevent a decrease in fade performance, it is preferable that the cashew component is 30% by weight or more and the rubber component is 70% by weight or less. Further, the cashew component is 50% by weight or more, and the rubber component is 50% by weight. % Is preferable. Also,
In order to sufficiently improve the squealing performance, 90 cashew ingredients
% By weight or less, and the rubber component is preferably 10% by weight or more. Therefore, the preferable ratio of the cashew component to the rubber component is 30 to 90% by weight of the cashew component and 10 to 70% by weight of the rubber component, and more preferably 50 to 90% by weight of the cashew component and 10 to 50% by weight of the rubber component. It is.

The cashew / rubber composite dust can be blended with the friction material in an arbitrary ratio depending on the required squealing performance and the like, but is generally blended in a ratio of 1 to 20% by weight. it can. However, since this composite dust has an action as cashew dust, a preferred method of blending this composite dust is at least one of cashew dust used in friction materials blended as having excellent friction performance. Part is replaced with the composite dust. Thereby, the squealing performance can be improved without affecting various excellent friction performances.

Incidentally, in the friction material of the present invention, the fiber base material, the resin binder, and other fillers are the same as those in the prior art.

As the fiber base material, glass fiber, rock wool, silicate fiber, alumina fiber, carbon fiber,
Potassium titanate fiber, inorganic fiber such as slag wool, steel fiber, stainless steel fiber, metal fiber such as copper fiber, aramid fiber, novoloid fiber, nylon fiber,
Organic fibers such as rayon fibers can be used. And these fibers are used alone or in appropriate combination,
It can be used according to the specific type or application of the friction material.

As the resin binder, phenol resin, melamine resin, epoxy resin, polyimide resin, polyester resin, rubber such as SBR, or the like can be used. However, among these, a phenol resin or a modified product thereof is also the most commonly used one, which is preferable.

Examples of the filler include fillers such as barium sulfate and calcium carbonate, solid lubricants such as graphite, molybdenum disulfide and trimonized antimony, and metals such as cashew dust, copper powder, zinc powder and brass powder. An abrasive agent such as powder or silica, or other additives for adjusting friction can be used.

The friction material of the present invention is prepared by mixing the above-mentioned cashew / rubber composite dust with a fiber base material, a resin binder, and other fillers, preforming the mixture, and then heating and pressing. It can be manufactured by a usual thermoforming method.

[0019]

According to the present invention, since the cashew nut shell liquid contains a cashew / rubber composite dust composed of a composite of a cured product component and a rubber component, the squealing performance is obtained by the vibration damping action of the rubber component of the cashew / rubber composite dust. And the occurrence of squeal during braking is reduced. Since the heat resistance of the rubber component is enhanced by the cured product component of the cashew nut shell liquid that is integrally compounded with the rubber component, a decrease in fade performance is prevented.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to an embodiment in which the present invention is applied to a disc brake pad.

<Production of Cashew / Rubber Composite Dust> First, a cashew / rubber composite dust composed of a composite of a cured component (cashew component) of a cashew nut shell liquid and a rubber component used in an embodiment of the present invention was prepared. It was manufactured as follows.

The cashew / rubber composite dust used in Examples 1 to 5 was prepared by kneading rubber, sulfur as a vulcanizing agent, carbon black, and an antioxidant in advance, and adding the mixture to a cashew nut shell liquid. The polymer (average degree of polymerization 4.0) and furfural were added and further mixed, and then heated (polymerized (condensed)). The obtained cured product was cooled and then pulverized. This manufacturing method is referred to as a “mixed polymerization” type.

In Examples 1 to 4, nitrile rubber (NBR) was used as the rubber, and in Example 5, styrene-butadiene rubber (SBR) was used. The ratio between the cashew component and the rubber component was changed. In Example 1, 90% by weight of the cashew component and 10% by weight of the rubber component, and in Examples 2 and 5, 70% by weight of the cashew component and 30% by weight of the rubber component
In Example 3, cashew component 50% by weight, rubber component 50% by weight, Example 4 30% by weight cashew component,
The rubber component was 70% by weight.

The cashew / rubber composite dust used in Example 6 was prepared by using fine cashew dust powder prepared in advance.
It was produced by granulating using a viscous liquid of rubber to which a vulcanizing agent (sulfur), carbon black and an antioxidant were added, and drying by heating. In addition, this manufacturing method is called "granulation" type.

Here, NBR was used as the rubber, and the ratio was 70% by weight of the cashew component and 30% by weight of the rubber component.

The types of the cashew / rubber composite dust (composite dust) thus produced, the ratio of the cashew component (% by weight), the ratio of the rubber component (% by weight) and the type of rubber are shown in FIG. 1 together.

<Manufacture of Pads> The disc brake pads (for PD51 type calipers) of Examples 1 to 6 were manufactured using the cashew rubber composite dust manufactured as described above.

Here, the friction material had the composition shown in Table 1 below.

[0029]

[Table 1]

Then, the friction material raw material of this composition including the cashew rubber composite dust is sufficiently and uniformly mixed by a V-shaped blender, and then the powdery mixture is charged into a preforming mold, and at room temperature, 200 kg / cm. ^The preform was pressed at a pressure of ² for 1 minute. The preform of the friction material was set in a thermoforming mold together with a back metal having a surface coated with a phenol resin adhesive in advance, and a pressure of 400 kg / cm ² was applied.
Thermoforming at a temperature of 60 ° C. for 10 minutes. And this is 2
Heat treatment was performed at 50 ° C. for 120 minutes. Thus, a disc brake pad was obtained.

Further, for comparison with these examples,
The disc brake pads of Comparative Example 1 and Comparative Example 2 were manufactured in the same manner as in Example. Here, Comparative Example 1 uses cashew dust in place of the cashew / rubber composite dust in the formulation of Table 1 above. Therefore, the friction material of Comparative Example 1 contains 5% by weight of cashew dust. In Comparative Example 2 , rubber dust was used in place of the cashew / rubber composite dust in the composition shown in Table 1 above. The rubber dust is made of NBR.

<Evaluation Test> Example 1 manufactured as described above
The fade performance and squeal performance of the disc brake pads of Example 6 and Comparative Examples 1 and 2 were tested and evaluated, respectively.

Regarding the fade performance, see PD51-18.
Using V-type caliper brake, inertia 5.0kg
The first fade was performed under the condition of f · m · s ² according to JASO-C406-82, and the minimum friction coefficient μ at the time of the fade was measured.

Further, regarding the squealing performance, the vehicle speed is 10 to 5
The state of occurrence of brake squeak (noise) at 0 km / h, brake fluid pressure of ^{2 to} 40 kg / cm ² , and temperature of 50 to 200 ° C. was examined and evaluated according to the following criteria. ：: No squeal generated □: Slight squeal generated △: Squeal generated slightly ×: Squeal generated <Test results> The results of the above tests are shown in FIG.

As shown in FIG. 1, the disc brake pads of Examples 1 to 6 using the cashew / rubber composite dust composed of the cashew component and the rubber component provided good results in fade performance and squeal performance. Obtained.

That is, in Comparative Example 1 in which only cashew dust was used, the minimum μ at the time of fade was relatively high at 0.20, but squealing occurred at the time of braking. In Comparative Example 2 using dust, the squealing performance was particularly excellent, but the minimum friction coefficient μ during fading was as low as 0.12, and the fading performance was poor. On the other hand, in Example 1 in which the composite dust containing 90% of the cashew component and 10% of the rubber component was used, although the minimum friction coefficient μ at the time of fading was the same as that of Comparative Example 1, the squealing performance was obtained. Have been improved. In addition, each rubber component is 3
In Examples 2 and 3 in which 0% and 50% were set, the minimum friction coefficient μ at the time of fading was slightly reduced, but the squealing performance was significantly improved.

However, in Example 4 in which the rubber component was 70%, the squealing performance was remarkably improved, but the minimum friction coefficient μ at the time of fading tends to decrease. for that reason,
It is understood that the rubber component of the composite dust is preferably 70% or less, and more preferably 50% or less. Also, from the standpoint of squeal performance, the rubber component is 10%
In Example 1, since the brake squeal is slightly generated, it is understood that the rubber component of the composite dust is preferably 10% or more.

Further, the ratios of the cashew component and the rubber component were the same between Example 2, Example 5 and Example 6, and the type of rubber used and the method of producing composite dust were different.
The same results are obtained for the minimum friction coefficient μ and the brake squeal performance during these fades. From this, it can be seen that there is no difference between the fade performance and the squealing performance depending on the type of rubber and the method of producing the composite dust.

In the above, the disc brake pad has been particularly described as an example. However, the present invention is not limited to this, and various friction materials such as lining of a drum brake or clutch facing are used. Can be applied to

[0040]

As described above, the brake pad of the present invention comprises a friction material containing a fibrous base material, a resin binder, and a filler, and as a filler, a cured material component of cashew nut shell liquid. Cashews composed of composites with rubber components
Contains rubber composite dust and cashew nut shell
The weight ratio of the liquid cured product component to the rubber component is
The cured component of the shoe nut shell liquid is 30 to 9
0% by weight, and the rubber component is 10 to 70% by weight .

Accordingly, the generation of squeal during braking can be reduced by the rubber component of the cashew / rubber composite dust, and the heat resistance of the rubber component can be increased by the cured component of the cashew nut shell liquid integrated with the rubber component. Therefore, it is possible to prevent a decrease in the friction coefficient μ at the time of fading. In addition, since cashew / rubber composite dust also has the effect of cashew dust,
Friction characteristics such as abrasion resistance and stability of friction coefficient of the brake pad can be maintained and improved. Therefore, blanking
By replacing at least a part of the cashew dust of the rake pad with the cashew / rubber composite dust, it is possible to improve the squealing performance without affecting other friction characteristics.

[Brief description of the drawings]

FIG. 1 shows cashew / rubber composite dust used for disc brake pads of Examples and Comparative Examples of the present invention;
It is a table | surface figure which shows the result of the evaluation test.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toru Honma 1st Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Masaaki Kobayashi 2-1, Asahimachi, Kariya City, Aichi Prefecture Aisin Seiki Co., Ltd. (56) References JP-A-62-261725 (JP, A) JP-A-63-293335 (JP, A) JP-A-63-66232 (JP, A) JP-A-5-320622 (JP, A) (58) Fields surveyed (Int.Cl. ⁶ , DB name) C08J 5/00-5/02 C08J 5/12-5/22 C09K 3/14 F16D 69/02

Claims (1)

(57) [Claims] 1. A friction material comprising a fiber base material, a resin binder, and a filler, wherein the filler comprises a cashew / rubber composite dust comprising a composite of a cured component of a cashew nut shell liquid and a rubber component. And Kash
Of the hardened component and rubber component of nut shell liquid
The quantitative ratio is the cured product of the cashew nut shell liquid.
The content is 30 to 90% by weight, and the rubber component is 10 to 70 weight
Brake pad characterized in that the amount is%.