JP4438486B2 - Friction material - Google Patents

Description

  The present invention relates to a friction material used for a disk pad, a brake lining or the like of an automobile.

  This type of friction material generally includes a fiber base selected from organic fibers, inorganic fibers, metal fibers, and the like, a powder raw material composed of a friction modifier and a filler, and a binder composed of a phenol resin and the like. It is manufactured by mixing and thermoforming the mixed raw material composition.

  In addition, in this type of friction material, an antimony compound has been conventionally added for the purpose of ensuring wear resistance in a high temperature range and suppressing deterioration of the face-to-face attack by a metal catch generated in the high temperature range. However, the use of antimony compounds has been refrained from the viewpoint of environmental problems, and alternative raw materials have been used.

  As such a friction material, for example, a friction material using tin and / or tin sulfide as an alternative raw material for an antimony compound has been proposed for the purpose of ensuring wear resistance in a high temperature range (Patent Document 1). reference).

  In addition, a friction material containing titanium sulfide and metal sulfides other than metal composite sulfides as an alternative raw material for antimony compounds for the purpose of suppressing deterioration of the face-to-face attack due to metal catches generated at high temperatures. It has been proposed (see Patent Document 2).

Furthermore, for the purpose of improving wear resistance and maintaining lubricity at high temperatures, a friction material containing a nitrogen acid compound composed of a nitrogen compound and an acid as a flame retardant has been proposed as an alternative raw material for the antimony compound. (See Patent Document 3).
Japanese Patent Laid-Open No. 2002-226834 JP 2003-313312 A JP 2002-173667 A

  However, according to the study by the present inventors, in the friction material described in Patent Document 1, tin and / or tin sulfide is antimony for wear resistance in a high temperature range (particularly 400 ° C. or more). It cannot be a complete replacement of the compound, and in order to ensure its performance, a large amount of other lubricants such as graphite must be added, resulting in a significant reduction in braking effectiveness.

  Further, in the friction material described in Patent Document 2, by adding a large amount of sulfide, a sulfide film is easily generated on the surface of the counterpart material, and the brake effect is greatly reduced and low-frequency squeal is generated. It tends to occur.

  Further, the friction material described in Patent Document 3 has a low effect on the fade resistance in a high temperature region (particularly 350 ° C. or more) due to decomposition of the nitrogen compound.

  The present invention has been made in view of the above-described circumstances, and provides a friction material capable of ensuring wear resistance, a face-to-face attack suppression effect and fade resistance while suppressing the use of an antimony compound as much as possible. Objective.

  In order to achieve the above object, the present inventors have intensively studied alternative raw materials having properties close to the properties of the antimony compound such as wear resistance. The present invention has been found experimentally as a result of such studies.

That is, in the invention according to claim 1, in the friction material including the fiber base material, the friction modifier, and the binder, at least one of zinc stannate (ZnSnO ₃ ) and zinc hydroxystannate (ZnSn (OH) ₆ ) is present. It is contained and the content is characterized by being greater than 0.05% by volume and less than 25% by volume.

Here, at least one of zinc stannate and zinc hydroxystannate is contained, and the content thereof is greater than 0.05% by volume and less than 25% by volume. Any one of these is contained in an amount larger than 0.05% by volume and less than 25% by volume, or when both are contained, the total content of both is more than 0.05% by volume. is that a greater than 25% by volume.

  ADVANTAGE OF THE INVENTION According to this invention, the friction material which can ensure abrasion resistance, a face-attack attack inhibitory effect, and fade resistance can be provided, suppressing use of an antimony compound as much as possible.

Furthermore, as in the invention described in claim 2 , the content is more preferably 1% by volume or more and 10% by volume or less.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below.

  FIG. 1 is a diagram showing a schematic configuration of a brake pad 10 as a friction material according to an embodiment of the present invention, and schematically shows a positional relationship between the brake pad 10 and a rotating rotor 20. Moreover, in FIG. 1, (b) is AA schematic sectional drawing of (a).

  As shown by the arrow Y1 in FIG. 1A, when the rotor 20 as the counterpart material is rotating, the brake pad 10 is in the direction of the arrow Y2 in FIG. Pushed in the direction. In this state, the rotor 20 slides, whereby a braking action is exhibited. The rotor 20 is made of an iron-based metal.

  The brake pad 10 of this embodiment is a bond made of a fiber base material selected from inorganic fibers, organic fibers, metal fibers, etc., a powder raw material consisting of a friction modifier and a filler, a binder resin such as a phenol resin, and the like. The raw material composition obtained by mixing with the material is thermoformed.

  Here, in the brake pad 10 of the present embodiment, as the fiber base material, a fiber base material used for a general brake pad, that is, a metal fiber, an organic fiber, an inorganic fiber, or the like may be used.

  Copper fiber, steel fiber or stainless fiber can be used as the metal fiber, aramid fiber or carbon fiber can be used as the organic fiber, and glass fiber or potassium titanate can be used as the inorganic fiber. A fiber, a ceramic fiber, a calcium silicate fiber, etc. are employable.

  Moreover, as a friction modifier, you may use the friction modifier employ | adopted as a general brake pad, ie, a lubricant, an inorganic oxide powder, etc.

  For example, graphite (graphite), molybdenum disulfide, zinc sulfide, etc. can be employed as the lubricant, and silica, alumina, silicon carbide, zirconium oxide, zirconium silicate, etc. can be employed as the inorganic oxide powder. it can.

  Further, as the filler, an inorganic material and an organic material are usually used in combination. Barium sulfate, calcium carbonate, calcium hydroxide, mica, kaolin, talc, etc. can be adopted as inorganic fillers, and cashew dust, rubber dust, etc. can be adopted as organic fillers. it can.

  Moreover, a general binder resin can be adopted as the binder. Specifically, urea resin, melamine resin, epoxy resin, urethane resin, polyimide resin, etc. or modified resins thereof can be employed as well as commonly used powdery phenol resins.

Thus, in the brake pad 10 as a friction material composed of a fiber base material, a friction modifier, a binder, and the like, in this embodiment, zinc stannate (ZnSnO ₃ ) and zinc hydroxystannate are further used as extreme pressure additives. At least one of (ZnSn (OH) ₆ ) is contained, and the content thereof is less than 25% by volume.

  Here, at least one of zinc stannate and zinc hydroxystannate is contained, and the content is less than 25% by volume means that any one of zinc stannate and zinc hydroxystannate is 25 alone. If it is contained less than volume% or both are contained, the total content of both is less than 25 volume%.

  By including at least one of these zinc stannates and zinc hydroxystannates, it is possible to obtain desired wear resistance, face-to-face attack suppression effect, and fade resistance while considering environmental issues.

  Furthermore, the hardness of these tin compounds such as zinc stannate and zinc hydroxystannate is almost the same as that of the disk rotor 20 which is the counterpart material, and there is almost no adhesion to the counterpart material sliding surface, and within the above content range. If there is, there is almost no effect on braking, noise and vibration.

  In addition, in the brake pad 10 of this embodiment, it is possible to obtain a higher effect by using it together with an antimony compound as long as environmental problems allow.

  And according to the brake pad 10 of this embodiment which has such a feature point, it is a friction material which can ensure abrasion resistance, a confrontation attack suppression effect, and fade resistance, suppressing use of an antimony compound as much as possible. Can be provided.

  In addition, although content of an above-described tin compound is less than 25 volume%, since it becomes the tendency for brake effect to fall that it is 25 volume% or more, it is because it is not suitable for practical use.

  Moreover, it is preferable that this content is larger than 0.05 volume%. This is because if 0.05% by volume or less, the effect is small, and metal catching is likely to occur at high temperatures. If it says further, it is more preferable that this content is 1 volume% or more and 10 volume% or less.

  The brake pad 10 of the present embodiment is manufactured through a manufacturing process as shown in FIG. 2 using the raw material composition containing the tin compound described above. FIG. 2 is a process diagram showing a method for manufacturing the brake pad 10 according to the present embodiment.

(Weighing process)
First, a fiber base material, a powder raw material composed of a friction modifier, a filler, and the like, a binder, and a powder of the tin compound are weighed at a predetermined composition ratio.

(Mixing process)
Each measured raw material component is put into a mixer and mixed dry. For example, a general mixer such as an Eirich mixer can be used as the mixer. The raw material composition is produced through the steps up to here.

(Weighing process)
Next, this raw material composition is taken out from the mixer, and weighed to separate a predetermined amount.

  Subsequently, a predetermined amount of the raw material composition is put into a mold, and thereafter thermoforming is performed. Here, in order to make the separated raw material composition into a block body, a preliminary molding, that is, an extrusion molding may be performed using another mold before performing the main molding.

(Main molding process)
For example, in a mold heated to 160 ° C., the above-described separated raw material composition or the raw material composition used in the extrusion molding is put and pressed to produce a molded body.

(Heat treatment process)
Thereafter, the molded body produced by the main molding process is cured by, for example, heat treatment at 200 ° C. or higher. Thus, the brake pad 10 is completed.

  Hereinafter, examples of the present embodiment will be shown and described more specifically.

  Examples 1 to 4 and Comparative Examples 1 to 3 are shown below. Table 1 shows the raw material components and amounts used in the brake pads of these examples. The present invention is not limited to these examples.

この表１では、繊維基材としては、アラミド繊維、銅繊維を用い、摩擦調整剤としては黒鉛を用いている。

In Table 1, aramid fibers and copper fibers are used as the fiber base material, and graphite is used as the friction modifier.

  In Table 1, cashew dust, calcium hydroxide, mica, zirconium oxide, and barium sulfate were used as the filler, and powdered phenol resin was used as the binder as the binder.

As extreme pressure additives, zinc stannate (ZnSnO ₃ ) and zinc hydroxystannate (ZnSn (OH) ₆ ) and antimony sulfide were used for comparison. Here, in Table 1, the raw material composition, that is, the amount of each raw material component is volume% (vol%).

Example 1
Aramid fiber 10% by volume, copper fiber 5% by volume, graphite 5% by volume, cashew dust 10% by volume, calcium hydroxide 2% by volume, mica 10% by volume, zirconium oxide 1% by volume, barium sulfate 34% by volume, zinc stannate Weigh 3% by volume of (ZnSnO ₃ ) and 20% by volume of powdered phenolic resin. Of these raw materials, finely powdered raw material, powdered phenolic resin and zinc stannate (powdered raw material) are uniformly mixed by dry method for 5 minutes using an Eirich mixer. Thereafter, the remaining fiber raw material and coarse raw material were added and further mixed for 3 minutes to obtain a raw material mixture.

This raw material composition was put into a mold heated to 160 ° C. so as to have a predetermined shape, and pressed for 10 minutes under the condition of 200 kg / cm ² to produce a molded body. Thereafter, this molded body was cured at 230 ° C. for 3 hours to produce a brake pad of this example.

(Example 2)
10% by volume of aramid fiber, 5% by volume of copper fiber, 5% by volume of graphite, 10% by volume of cashew dust, 2% by volume of calcium hydroxide, 10% by volume of mica, 1% by volume of zirconium oxide, 27% by volume of barium sulfate, hydroxystannic acid 10% by volume of zinc (ZnSn (OH) ₆ ) and 20% by volume of powdered phenol resin were weighed and mixed, molded and cured in the same manner as in Example 1 to produce a brake pad of this example.

(Example 3)
10% by volume of aramid fiber, 5% by volume of copper fiber, 5% by volume of graphite, 10% by volume of cashew dust, 2% by volume of calcium hydroxide, 10% by volume of mica, 1% by volume of zirconium oxide, 31.5% by volume of barium sulfate, tin Zinc oxide (ZnSnO ₃ ) 2% by volume, zinc hydroxystannate (ZnSn (OH) ₆ ) 3.5% by volume, and powdered phenol resin 20% by volume were weighed, mixed, molded, and cured in the same manner as in Example 1 above. The brake pad of this example was produced.

In this example, the content of the extreme pressure additive is 5.5 as a total of 2% by volume of zinc stannate (ZnSnO ₃ ) and 3.5% by volume of zinc hydroxystannate (ZnSn (OH) ₆ ). % By volume.

Example 4
Aramid fiber 10% by volume, copper fiber 5% by volume, graphite 5% by volume, cashew dust 10% by volume, calcium hydroxide 2% by volume, mica 10% by volume, zirconium oxide 1% by volume, barium sulfate 34% by volume, antimony sulfide 2 Volume%, zinc stannate (ZnSnO ₃ ) 1 volume%, and powdered phenol resin 20 volume% were weighed and mixed, molded and cured in the same manner as in Example 1 to produce a brake pad of this example. In this example, a trace amount of an antimony compound is contained to an extent that is environmentally acceptable.

(Comparative Example 1)
Aramid fiber 10% by volume, copper fiber 5% by volume, graphite 5% by volume, cashew dust 10% by volume, calcium hydroxide 2% by volume, mica 10% by volume, zirconium oxide 1% by volume, barium sulfate 36.95% by volume, tin Zinc acid (ZnSnO ₃ ) 0.05% by volume and powdered phenol resin 20% by volume were weighed and mixed, molded and cured in the same manner as in Example 1 to produce a brake pad of this example.

(Comparative Example 2)
Aramid fiber 10% by volume, copper fiber 5% by volume, graphite 5% by volume, cashew dust 10% by volume, calcium hydroxide 2% by volume, mica 10% by volume, zirconium oxide 1% by volume, barium sulfate 12% by volume, zinc stannate 25% by volume of (ZnSnO ₃ ) and 20% by volume of powdered phenol resin were weighed and mixed, molded and cured in the same manner as in Example 1 to produce a brake pad of this example.

(Comparative Example 3)
Aramid fiber 10% by volume, copper fiber 5% by volume, graphite 5% by volume, cashew dust 10% by volume, calcium hydroxide 2% by volume, mica 10% by volume, zirconium oxide 1% by volume, barium sulfate 33% by volume, antimony sulfide 4 Volume% and 20% by volume of powdered phenol resin were weighed and mixed, molded and cured in the same manner as in Example 1 to produce a brake pad of this example.

  The brake pad of Comparative Example 3 is a brake pad containing a conventional general antimony compound, and the characteristics of the brake pad of this example serve as a comparative reference in the following brake pad evaluation.

(Brake pad evaluation)
The brake pads of Examples 1 to 4 and Comparative Examples 1 to 3 were investigated by evaluating the average coefficient of friction, the coefficient of friction during fading, the amount of wear, the occurrence of metal catch, and the impact on the environmental load. The results of evaluating the characteristics of the brake pads of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 2 below.

平均摩擦係数は、日本自動車規格（ＪＡＳＯ）による一般性能試験（Ｃ４０７に準拠）の平均摩擦係数を表している。この平均摩擦係数はブレーキパッドの効きの指標となるものであり、その値が大きいほどブレーキ効きがよいことになる。

The average friction coefficient represents the average friction coefficient of a general performance test (conforming to C407) according to the Japan Automobile Standard (JASO). This average coefficient of friction serves as an index of the effectiveness of the brake pad, and the larger the value, the better the braking effectiveness.

  The friction coefficient at the time of fading represents the minimum friction coefficient at high temperature during the evaluation of the average friction coefficient. The friction coefficient at the time of fading serves as an index of fading resistance. The larger the value, the better the fading resistance.

  The amount of wear is determined by measuring the amount of wear at each temperature (100 ° C, 200 ° C, 300 ° C, 400 ° C) in a wear test according to temperature (according to C406) by JASO and converting it to the amount of wear per 1000 braking cycles. And evaluated. This amount of wear serves as an index of wear resistance, and the smaller the value, the better the wear resistance.

  The metal catch was evaluated for the following criteria by checking whether or not the metal catch was generated when measuring the wear amount at each temperature in the wear test. “◎”: Extremely good (no metal catch), “◯”: Good (less than several small metal catches with a major axis of 3 mm or less), “△”: Slightly bad (many small metal catches), “×”: Bad (major axis) There is a large metal catch of 5mm or more).

  Regarding the impact on the environmental load, except for the brake pad of Comparative Example 3 containing an antimony compound, there is no problem, that is, {circle around (0)}, but Example 4 contains an antimony compound although it is within an allowable range. Therefore, the evaluation is “△”. Of course, Comparative Example 3 containing an antimony compound is indicated as “x”.

(Evaluation result of Example 1)
Average friction coefficient is 0.40, friction coefficient at fade is 0.27, wear is 100 ° C: 0.08mm, 200 ° C: 0.09mm, 300 ° C: 0.26mm, 400 ° C: 0.45mm, metal The occurrence of catches was 100 ° C. to 300 ° C .: ◎, 400 ° C .: ◯.

(Evaluation result of Example 2)
Average friction coefficient is 0.40, friction coefficient at fade is 0.28, wear is 100 ° C: 0.08mm, 200 ° C: 0.10mm, 300 ° C: 0.27mm, 400 ° C: 0.47mm, metal The occurrence of catches was 100 ° C. to 300 ° C .: ◎, 400 ° C .: ◯.

(Evaluation result of Example 3)
Average friction coefficient is 0.40, friction coefficient during fading is 0.27, wear amount is 100 ° C: 0.08 mm, 200 ° C: 0.09 mm, 300 ° C: 0.24 mm, 400 ° C: 0.44 mm, metal The occurrence of catches was 100 ° C. to 300 ° C .: ◎, 400 ° C .: ◯.

(Evaluation result of Example 4)
Average friction coefficient is 0.40, friction coefficient at fade is 0.25, wear is 100 ° C: 0.07mm, 200 ° C: 0.09mm, 300 ° C: 0.22mm, 400 ° C: 0.42mm, metal The occurrence of catch was 100 ° C. to 400 ° C .: A.

(Evaluation result of Comparative Example 1)
Average friction coefficient is 0.42, friction coefficient at fade is 0.21, wear is 100 ° C: 0.10mm, 200 ° C: 0.12mm, 300 ° C: 0.32mm, 400 ° C: 0.67mm, metal The occurrence of catches was 100 ° C .: 、, 200 ° C .: ◯, 300 ° C .: Δ, 400 ° C .: x.

(Evaluation result of Comparative Example 2)
Average friction coefficient is 0.32, friction coefficient at fade is 0.26, wear is 100 ° C: 0.08mm, 200 ° C: 0.11mm, 300 ° C: 0.18mm, 400 ° C: 0.39mm, metal The occurrence of catch was 100 ° C .: ◎, 200 ° C .: ◯, 300 ° C. and 400 ° C .: Δ.

(Evaluation results of Comparative Example 3)
Average friction coefficient is 0.40, friction coefficient at fade is 0.24, wear amount is 100 ° C: 0.08mm, 200 ° C: 0.09mm, 300 ° C: 0.25mm, 400 ° C: 0.48mm, metal The occurrence of catch was 100 ° C. to 400 ° C .: A.

  About the mixed state in a brake pad, in Examples 1-4 and Comparative Example 3, the mixing was uniform, but in Comparative Examples 1 and 2, the mixing was non-uniform. This is because in Comparative Example 1 and Comparative Example 2, the content of the tin compound is too small or too large.

In Comparative Example 1, the content of zinc stannate (ZnSnO ₃ ) is small, and the brake pad using the conventional antimony compound is substantially similar to the composition excluding the antimony compound. The effect has not been demonstrated.

  That is, as shown in Table 2, in Comparative Example 1, the friction coefficient at the time of fading is low, the amount of wear in the high temperature range is large, and metal catches are generated in the high temperature range. Suppressing effect and fading resistance have not been secured.

Further, in Comparative Example 2 in which the content of zinc hydroxystannate (ZnSn (OH) ₆ ) is too large, although the occurrence of metal catches is small, the average friction coefficient is greatly reduced, which is not suitable for practical use. In Comparative Example 2, the adhesion of zinc hydroxystannate to the disk rotor sliding surface, which is the counterpart material, has been slightly confirmed.

  And in Examples 1-4, the antimony compound is not used or its use is suppressed as much as possible, and by setting the content of the tin compound as an alternative raw material in the range shown in the above embodiment, the average friction coefficient, Fade friction coefficient, wear amount, occurrence of metal catch, impact on environmental load, all characteristics are no problem, ensuring wear resistance, face-to-face attack suppression effect and fade resistance .

  As described above, the present invention has been described with reference to the above-described embodiments, examples, and the like. However, the present invention is not limited to the application as a brake pad for an automobile disc brake shown in FIG. Needless to say, the present invention can be applied to pads, various brake pads other than automobiles such as automobiles and railway vehicles, brake linings, and clutch facings.

  In short, the present invention can be applied to a friction material composed of a fiber base material, a friction modifier and a binder.

It is a figure showing a schematic structure of a brake pad concerning an embodiment of the present invention. It is process drawing which shows the manufacturing method of the brake pad which concerns on the said embodiment.

Explanation of symbols

10: Brake pad as friction material, 20: Rotor.

Claims (2)

In a friction material comprising a fiber base material, a friction modifier and a binder,
A friction material comprising at least one of zinc stannate and zinc hydroxystannate, the content of which is greater than 0.05% by volume and less than 25% by volume. The friction material according to claim 1 , wherein the content is 1 volume% or more and 10 volume% or less.

Images