JP7043930B2 - Manufacturing method of non-fired ceramic friction material, brake pad and non-fired ceramic friction material - Google Patents

Description

The present invention relates to a non-fired ceramic friction material, a brake pad, and a method for manufacturing a non-fired ceramic friction material.

Conventionally, a brake pad including a lining that comes into contact with a disc rotor and a back plate to which the lining is fixed is known (for example, Patent Documents 1 and 2).
As a brake pad of this type, one using ceramics as a friction material is known.

Japanese Unexamined Patent Publication No. 11-31127 Japanese Unexamined Patent Publication No. 2008-281060 Japanese Unexamined Patent Publication No. 2008-239433

In this type of brake pad, wear debris is generated by friction between the disc rotor and the lining, but if the particle size of the wear debris is small, it may be scattered in the atmosphere.
Therefore, the present invention provides a method for manufacturing a non-fired ceramic friction material, a brake pad, and a non-fired ceramic friction material that can suppress the scattering of wear debris caused by friction between the disc rotor and the lining into the atmosphere. It is an object.

The non-fired ceramic friction material of the embodiment is a ceramic particle composed of at least one of silicic acid and silicate, and has a collection efficiency of 50% or less of particles having an aerodynamic diameter of 2.5 μm or less. It is provided with a matrix obtained by adhering the ceramic particles remaining after classification in (1) to each other via an adhesive layer and solidifying the ceramic particles, and a friction material composition.
According to this configuration, when forming a brake pad using a non-fired ceramic friction material, it has sufficient strength, can obtain desired friction characteristics, and suppresses scattering of wear debris into the atmosphere. be able to.

In the above configuration, the ceramic particles may be ceramic particles in which particles having an aerodynamic diameter of 7.0 μm or less are collected with a collection efficiency of 50%.
According to this configuration, the collected silica powder does not effectively contain particles having a particle size corresponding to so-called PM2.5, and the wear powder is more reliably scattered into the atmosphere. Can be suppressed.

In the above configuration, the adhesive layer may contain metal cations.
According to this configuration, ceramic particles composed of at least one of silicic acid and silicate can be reliably adhered to each other, have sufficient strength, and have a desired performance including desired frictional properties (a lining (). Alternatively, a brake pad) can be formed.

The brake pad of the embodiment includes a lining made of any of the above-mentioned non-fired ceramic friction materials.
According to this configuration, it is possible to easily obtain a brake pad having sufficient strength, desired friction characteristics, and a lining capable of suppressing the scattering of wear debris into the atmosphere.

Further, in the method for producing a non-fired ceramic friction material of the embodiment, 50% or less of ceramic particles composed of at least one of silicic acid and silicate and particles having an aerodynamic diameter of 2.5 μm or less are captured. The classification process of classifying and removing by collecting efficiency, the grinding process of activating at least the surface of the ceramic particles remaining by the classification by mechanochemical treatment, and the mixing of the friction material composition with the ceramic particles whose surface has been activated. A mixing process, a kneading process in which an alkaline solution is added to a mixture of ceramic particles and a friction material composition and kneaded to form a ceramic gel, and molding is performed while defoaming from the ceramic gel to obtain a ceramic temporary molded body. It includes a foaming process and a solidification / drying process of solidifying and drying the ceramic temporary molded body at a predetermined temperature of 200 ° C. or lower to obtain a non-fired ceramic friction material.

According to this configuration, when forming a brake pad while suppressing energy consumption during manufacturing, it has sufficient strength, desired friction characteristics can be obtained, and wear debris is suppressed from scattering into the atmosphere. It is possible to obtain a non-firing ceramic friction material that can be used.

In the above configuration, in the solidification / drying process, the ceramic temporary molded product is dried in a constant temperature furnace at a first temperature for a first predetermined time, and further at a second temperature higher than the first temperature for a first predetermined time. A long second predetermined time drying may be performed.
According to this configuration, it is possible to obtain a non-fired ceramic friction material having sufficient strength and capable of obtaining desired friction characteristics.

FIG. 1 is a schematic perspective view of a disc brake to which the disc pad of the embodiment is applied. FIG. 2 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is an external perspective view of the brake pad of the embodiment. FIG. 4 is an explanatory diagram of the manufacturing process of the lining of the embodiment. FIG. 5 is an explanatory diagram of the collection efficiency of silica powder. FIG. 6 is an explanatory diagram of a processing state of the ceramic powder. FIG. 7 is a schematic configuration explanatory view of the solidified body of non-fired ceramics of the embodiment. FIG. 8 is an explanatory diagram of the effect of the embodiment.

Next, exemplary embodiments of the present invention will be described in detail with reference to the drawings.
The configurations of the embodiments shown below, as well as the actions and results (effects) brought about by the configurations, are examples. The present invention can also be realized by configurations other than those disclosed in the following embodiments. Further, according to the present invention, it is possible to obtain at least one of various effects (including derivative effects) obtained by the configuration.

FIG. 1 is a schematic perspective view of a disc brake to which the disc pad of the embodiment is applied.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
The disc brake 1 of the embodiment is a disc rotor 2 that is assembled to an axle hub (rotating body (not shown) and rotates integrally with wheels (not shown), and a caliper 3 that is arranged so as to straddle the peripheral edge of the disc rotor 2. And have.

In the following description, the axial direction of the disc rotor 2 is referred to as the rotor axial direction, the radial direction of the disc rotor 2 is referred to as the rotor radial direction, and the circumferential direction of the disc rotor 2 is referred to as the rotor circumferential direction. The rotor circumferential direction intersects the rotor radial direction.

The caliper 3 is supported by a mounting 11 fixed to a support member provided on the vehicle body, a caliper body 12 movably supported by the mounting 11 in the rotor axial direction, and a mounting 11 movably supported in the rotor axial direction. It includes a pair of brake pads 20, 30 and so on.

The caliper body 12 is movably attached to the mounting 11 in the rotor axial direction by a pair of slide pins 14. The caliper body 12 extends the disc rotor 2 from the vehicle body side so as to straddle the rotor axis direction. The caliper body 12 has a cylinder portion 12a into which a piston 15 (pressing member) is inserted at one end portion (left side, base end portion in FIG. 2) in the rotor axial direction. The caliper body 12 has a pair of claws 12b (pressing members) at the other end portion (right side, tip portion in FIG. 2) in the rotor axial direction. The claw 12b is located on the other side of the disc rotor 2 in the rotor axial direction, and is positioned at a distance from the disc rotor 2 in the rotor axial direction.

As shown in FIG. 2, the piston 15 is located on one side of the disc rotor 2 in the rotor axial direction and is spaced apart from the disc rotor 2 in the rotor axial direction. The piston 15 is included in the caliper 3. The piston 15 advances toward the disc rotor 2 by hydraulic pressure, and pushes the brake pad 20 interposed between the piston 15 and the disc rotor 2 toward the disc rotor 2. Specifically, the piston 15 has a pressing portion 15a (pressing surface) included in the end portion on the brake pad 20 side, and the pressing portion 15a pushes the brake pad 20 toward the disc rotor 2.

Along with this, the caliper body 12 moves due to the reaction force of the pressing force which is the pressing force of the pressing portion 15a, and the claw 12b of the caliper body 12 causes the brake pad 30 interposed between the disc rotor 2 and the claw 12b. Push toward the disc rotor 2.

More specifically, the claw 12b has a pressing portion 12c (pressing surface) included in the end portion on the brake pad 30 side, and the pressing portion 12c pushes the brake pad 30 toward the disc rotor 2. That is, the pair of brake pads 20 and 30 are pressed against the disc rotor 2 by the pressing portion 15a of the piston 15 or the pressing portion 12c of the claw 12b, respectively.
Further, a shim 40 is interposed between the back plates of the brake pads 20 and 30 and the caliper body 12.

Next, the configuration of the brake pad will be described.
In this case, the brake pad 20 and the brake pad 30 have the same configuration. Therefore, the brake pad 20 will be described below as an example.

FIG. 3 is an external perspective view of the brake pad of the embodiment.
The brake pad 20 is in contact with the back plate 21 having the first surface F1 and the first surface F1, is located on the side opposite to the first surface F1 with respect to the center in the thickness direction, and is substantially parallel to the first surface F1. It is provided with a lining 22 having a second surface F2.

The raw material of the lining 22 includes ceramic particles and a friction material raw material composed of at least one of silicic acid and silicate.
For example, ceramic particles composed of at least one of silicic acid and silicate, which are raw materials for the lining 22, are required to have at least a surface made of silicic acid and / or silicate. As the material of such ceramic particles, for example, clay minerals such as bentonite, kaolinite, metakaolin, and montmorillonite, and SiO _{2 -} Al ₂ O3 based inorganic powders such as quartz and mullite can be used.
In addition, wastes such as fly ash, glitter, glass, paper sludge, and aluminum dross can be used as ceramics.

Examples of ceramics whose surface is composed of silicic acid and / or silicate include silicon nitride, silicon carbide, aluminosilicate (zeolite), sialon (SiAlON), siliconoxynitride (SiON), and siliconoxycarbide (silicon). SiOC) and the like.

Further, as the friction material, the conventional friction material composition can be used as it is. That is, as the friction material composition, a friction material composition containing a fiber base material, an organic filler and an inorganic filler can be used.

Here, as the base fiber, glass fiber, carbon fiber, metal fiber, ceramic fiber, rock wool, aramid fiber, acrylic fiber and the like can be used.

As the organic filler, organic powder such as cashew dust and rubber dust can be used.

As the inorganic filler, inorganic powder particles such as alumina and zirconia, lubricants such as graphite, antimony sulfide and tin sulfide, and metal powder particles such as copper, aluminum and zinc can be used.

Next, the lining manufacturing process will be described.
FIG. 4 is an explanatory diagram of the manufacturing process of the lining of the embodiment.
The manufacturing process of the lining 22 is roughly classified into a classification step (step S10), a grinding step (step S11), a mixing step (step S12), a kneading step (step S13), a defoaming step (step S14), and a solidification step. -There is a drying step (step S15).

Hereinafter, they will be described in order.
<Classification process>
Silica (SiO ₂ ) powder as ceramic particles is classified by a classifier for classifying particles having an aerodynamic diameter of 2.5 μm or less with a collection efficiency of 50% or less (step S10).

FIG. 5 is an explanatory diagram of the collection efficiency of silica powder.
As a result, the silica powder collected by the classifier (mainly particles having an aerodynamic diameter of 2.5 μm or more) is used as the raw material ceramic particles. As a result, as shown in FIG. 5, the raw material ceramic particles are in a state in which particles having a particle diameter corresponding to so-called PM2.5 are hardly contained.

Further, if the silica powder is classified by a classification device that classifies particles having an aerodynamic diameter of 7.0 μm or less with a collection efficiency of 50%, the collected silica powder contains particles corresponding to so-called PM2.5. Particles of diameter are not effectively included.

<Grinding process>
Next, the silica powder is ground to obtain a silica powder whose surface has been activated by mechanochemical treatment (step S11).
In this case, a metal capable of forming a metal cation in a portion that can come into contact with the silica powder as ceramic particles (for example, a crushing member such as a crushing ball, a pestle, a wear plate, a rod, and a crushing container such as a crushing drum and a mortar). Since the treatment is performed using an apparatus using a material containing atoms, the surface of the ceramic particles can be further activated.

FIG. 6 is an explanatory diagram of a processing state of the ceramic powder.
FIG. 6A is an explanatory diagram of the ceramic powder 51 as a raw material before the grinding step.
As shown in FIG. 6A, the ceramic powder (silica powder) 51 as a raw material before the grinding step is a homogeneous powder having crystallinity as a whole and corresponds to so-called PM2.5. There are almost no particles with the same particle size.

In the grinding step, specifically, by grinding the ceramic powder 51 with a planetary ball mill for 15 minutes, as shown in FIG. 6 (b), the surface is amorphous mechanically amorphized. The activated ceramic powder 52 having the quality active layer 52a is obtained.

That is, in the amorphous active layer 52a of the activated ceramic powder 52, the silica network structure of the ceramic powder 51 is in an amorphous state (amorphous state), and is easily eroded by alkali. ing.
Further, the amorphous active layer 52a of the activated ceramic powder 52 is in a state where metal cations (for example, Fe, Si, Al, etc.) are mixed from the material of the ball or container for grinding in the grinding step. It has become.

In this case, ideally, grinding until the change in particle size distribution with time is considered to facilitate dissolution by an alkaline aqueous solution, and the obtained solidified ceramics is considered to be dense and have high mechanical strength. .. However, it is considered that the state is effectively sufficient by grinding with a planetary ball mill for about 15 minutes.

In the above description, a planetary ball mill was used in the grinding process, but in order to perform mechanochemical action, it is effective to apply various forces such as impact, friction, compression, and shear in a complex manner. In addition to the above-mentioned planetary ball mill, specific examples thereof include a mixing device such as a ball mill, a vibration mill, and a medium stirring type mill, a ball medium mill, a roller mill, and a crusher such as a mortar. In addition, it is not necessary to apply various forces such as impact, friction, compression, and shear in a complex manner. For example, a jet crusher capable of exerting mainly impact, crushing, and other forces on the object to be crushed. Etc. can also be used. Further, the device for performing the mechanochemical action is not limited to these.

<Mixing process>
Next, a predetermined friction material composition containing an abrasive as another raw material is added to the silica powder whose surface has been activated in the grinding step (step S12), and a mixing treatment is performed (step S13).

Specifically, the mixing process is performed for 900 minutes by, for example, a rotary ball mill.

<Alkaline treatment process>
In the alkali treatment step, the activated ceramic powder 52 is added with an alkaline aqueous solution containing an alkali metal hydroxide and / or an alkaline earth metal hydroxide (step S14) and kneaded (step S15).

Devices for mixing and kneading the alkaline aqueous solution and the activated ceramic powder 52 include, for example, a dual arm kneader, a pressurized kneader, an Erich mixer, a super mixer, a planetary mixer, a Banbury mixer, and a continuous mixer. , Or a known device such as a continuous kneader.

It is also possible to use a vacuum clay kneader to remove unwanted air bubbles during the mixing and kneading steps. By removing unnecessary bubbles before solidification, it becomes easier to improve the density and strength of the obtained solidified ceramic body.

By this alkali treatment step, the amorphous active layer 52a is melted and dehydrated and condensed into a gel-like or highly viscous slurry-like state in which the abrasive particles are uniformly mixed.

In this case, metal cations such as iron ions Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , and aluminum ion Al ³⁺ contained in the amorphous active layer 52a are contained in the amorphous active layer 52a which is easily negatively charged. It is considered that an ionic bond is easily formed with the hydroxyl group (OH group) and the silanol group (Si—OH group).

<Defoaming process>
In the above alkali treatment step, since kneading is performed in the atmosphere, a gel-like or highly viscous slurry-like substance containing the activated ceramic powder 52 (hereinafter referred to as activated ceramic gel) has many bubbles. Includes.

Therefore, in the defoaming step, the activated ceramic gel containing the activated ceramic powder 52 subjected to the alkali treatment was placed in a molding die, pressurized by a press device, vibrated by a vibrating device, and depressurized by a depressurizing device. Defoaming treatment is performed in this state (step S16).
As a result, the density of the finally formed solidified ceramic body and the strength of the matrix are improved, and the abrasive particles can be more reliably held.

<solidification / drying process>
In the activated ceramic gel after defoaming, metal cations such as Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , and aluminum ion Al ^{3+ tend} to be negative-negative hydroxyl groups (OH groups) or silanol groups (Si-OH). It is attracted to the base) and is adsorbed on the surface of the activated ceramic powder 52. This adsorption state is generated on the surface of a plurality of activated ceramic powders 52 by one metal cation such as Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , and aluminum ion Al ³⁺ , and eventually the activated ceramic powder. The bonding force between the 52s will be increased.

Furthermore, when dehydration condensation occurs by binding a metal cation such as Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , aluminum ion Al ³⁺ and a hydroxyl group (OH group) or a silanol group (Si—OH group), it is active by chain polymerization. A matrix (base material) is formed by the chemical powder 52, and the grinding material mixed in the mixing step is held in the matrix having increased strength.

Then, the activated ceramic gel in this state is dried in a constant temperature furnace for a first predetermined time at a first temperature in a first solidification / drying step and at a second temperature higher than the first temperature for a second predetermined time. By going through the second solidification / drying step, the amorphous active layer 52a dissolved in the alkali treatment step is reprecipitated, so that the precipitation layer 54a is generated as shown in FIG. 6 (c).

During the formation of the precipitation layer 54a, metal cations such as Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , and aluminum ion Al ³⁺ are more fluidly activated. Hydroxy groups (OH groups) or silanols on the surface of the ceramic powder 52 are activated. An adhesive layer 54b that is more firmly bonded to the group (Si—OH group) and serves as an adhesive between the activated ceramic powders 52 is formed, and the strength of the solidified ceramic body is improved.

Specifically, the first solidification / drying step of drying in a constant temperature furnace at a first temperature = 60 ° C. for a first predetermined time = 300 minutes, and the second predetermined time = 900 minutes at a second temperature = 80 ° C. By going through the second solidification / drying step of drying, the amount of gel around the activated ceramic powder 52 can be reduced without increasing the strain, and it is possible to form a matrix with higher strength. It has become.

In this case, the first temperature in the first solidification / drying step and the second temperature in the second solidification / drying step may be appropriately selected depending on the type of ceramics as a raw material and the type and concentration of the alkaline aqueous solution. The first temperature is preferably in the range of room temperature to 60 ° C. The second temperature is preferably in the range of room temperature to 200 ° C. Further, the second temperature is higher than the first temperature, and the second predetermined time is preferably longer than the first predetermined time in order to obtain a denser matrix.

FIG. 7 is a schematic configuration explanatory view of the solidified body of non-fired ceramics of the embodiment.
FIG. 7 shows a state in which only the abrasive is contained in the non-fired ceramic solidified body for easy understanding.

The lining 22 includes a matrix 54MTX constituting a solidified body of non-fired ceramics.
The matrix 54MTX is configured such that the ceramic particles 54X having the above-mentioned precipitation layer 54a and the adhesive layer 54b are adhered to each other via the adhesive layer 54b.

The grinding material 60 is firmly held in the matrix 54MTX.
The matrix (base material) 54MTX of the unfired ceramic solidified body having such a structure obtained as a result of the above treatment has sufficient strength (shear strength of 17 Mpa or more) and surely holds the abrasive 60. It is possible to obtain a sufficient friction coefficient as a brake pad (for example, in the above example, the average friction coefficient Ave.μ = 0.45).

In the above description, the case where Fe ²⁺ , Fe ³⁺ , silica ion Si ⁴⁺ , aluminum ion Al ³⁺ , etc. are used as the metal cations mixed in the grinding step has been described, but the present invention is not limited to this, and other metal cations may be used. It is also possible to strengthen the bonds between the silica particles constituting the matrix.

As described above, according to the present embodiment, by configuring the lining as a lining capable of holding the abrasive by using non-fired ceramics, it is possible to manufacture a lining with energy saving, and by extension, a brake pad, and a brake pad lining. It is possible to demonstrate sufficient performance.

FIG. 8 is an explanatory diagram of the effect of the embodiment.
As described above, the matrix (base material) 54MTX of the non-fired ceramic solidified body is configured such that the ceramic particles 54X having the precipitation layer 54a and the adhesive layer 54b are adhered to each other via the adhesive layer 54b.

In this state, when the disc brake 1 is braked, a shearing force acts on the matrix 54MTX, and in this case, the adhesive layer 54b is most stressed.
Therefore, for example, when a shearing force acts along the broken line X, one ceramic particle 54X is separated from the matrix 54MTX as shown in the lower left of FIG.

Similarly, when a shearing force acts along the broken line Y, the three ceramic particles 54X are separated from the matrix 54MTX as shown in the lower left of FIG.

That is, when a shearing force acts on the matrix 54MTX, it is usually separated in units of one or more ceramic particles 54X, so that the size of the ceramic particles 54X is PM2.5 or larger as in the embodiment. By having the size of, it is possible to suppress the probability that PM2.5 is scattered in the air.

[2] Modification of Embodiment In the above description, in the classification step, silica (SiO ₂ ) powder as ceramic particles is classified, and particles having an aerodynamic diameter of 2.5 μm or less are classified with a collection efficiency of 50% or less. The silica powder (mainly particles with an aerodynamic diameter of 2.5 μm or more) collected by the classification device was used as the raw material ceramic particles, and the surface was first activated in the grinding step in the mixing step. Although surface-active alumina was added to the silica powder, it is also possible to add a thermoplastic resin to more reliably suppress the scattering of the wear powder into the atmosphere.

Here, the thermoplastic resin added is a usage mode assumed in a brake device in which the brake pad 20 is actually used, more specifically, a temperature band of the brake in which the brake pad 20 is assumed to be mainly used. The material is selected according to.

Further, the thermoplastic resin to be added is a thermoplastic resin having a difference between the heat distortion temperature and the melting point of 100 ° C. or higher, more preferably 150 ° C. or higher, and an alkali (for example, strong alkali) in the alkali treatment. It needs to be a thermoplastic resin that is resistant to potassium hydroxide solution).
More preferably, the heat distortion temperature of the thermoplastic resin 65 is 50 degrees or higher, and the melting point is 400 degrees or lower.

Such a condition is that in the temperature range from the heat distortion temperature to the melting point, the thermoplastic resin is in a softened state and exhibits properties similar to an eraser or clay, so that it takes in wear debris. In order to efficiently form a paste-like, granular, needle-like kneaded material having a size that does not scatter into the atmosphere, or a group of kneaded materials in which these kneaded materials adhere to each other, and without modification in alkali treatment. This is to maintain the characteristics.

The formation of the kneaded body by the thermoplastic resin added here will be described in more detail.
First, when the lining 22 of the brake pad 20 is pressed against the disc rotor 2, the disc rotor 2 and the lining 22 slide relative to each other, and friction causes wear debris of the base material of the lining 22 to be generated, and frictional heat causes the lining. And the temperature of the disc rotor rises. As a result, the thermoplastic positive resin held in the matrix of the lining 22 reaches the heat distortion temperature.

The thermoplastic resin that has reached the heat distortion temperature and is in a softened state is subjected to shearing force by the wear debris, and the softened body that is a part of the thermoplastic resin is separated.

At the same time, the softened body, which is a thermoplastic resin in a softened state, functions as a binder and is kneaded with abrasion powder as it is rolled in the gap between the disc rotor 2 and the lining 22, and is in the form of a paste or granules. Alternatively, a needle-shaped (leaf roll-shaped) kneaded body is formed.
Further, when the brake temperature is lowered, the kneaded bodies in the softened state are in a state of adhering to each other, forming a group of kneaded bodies having a larger size, and further suppressing scattering becomes possible.

The brake temperature at this time is set to substantially correspond to the temperature between the heat distortion temperature and the melting point of the thermoplastic resin contained in the lining 22 if the brake device is used as expected. Therefore, it is possible to reliably form the kneaded body and maintain the state in which the abrasion powder is taken in, and it is possible to suppress the abrasion powder from scattering into the atmosphere as a single fine particle.

Polyetheretherketone (PEEK) and nylon (registered trademark) are examples of thermoplastic resins that satisfy these conditions and can maintain the friction coefficient required for the brake pad 20 above the required predetermined value. ), Polyamide (PA) 6 and polyamide 66, polyphenylene sulfide (PPS), non-modified polypropylene (PP), polybenzimidazole (PBI) and the like.

Here, the thermal properties of these thermoplastic resins will be described in detail.
Since the polyetheretherketone has a heat distortion temperature of 155 ° C and a melting point of 340 ° C, the difference is 185 ° C. The thermal decomposition temperature is 450 ° C. or higher.
Since the polyamide 6 has a heat distortion temperature of 68 ° C. and a melting point of 225 ° C., the difference is 157 ° C. The thermal decomposition temperature is 320 ° C. or higher.

Since the polyamide 66 has a heat distortion temperature of 75 ° C. and a melting point of 265 ° C., the difference is 190 ° C. The thermal decomposition temperature is 350 ° C. or higher.
Since polyphenylene sulfide has a heat distortion temperature of 135 ° C. and a melting point of 290 ° C., the difference is 155 ° C. The thermal decomposition temperature is 500 ° C. or higher.

Since the non-denatured polypropylene has a heat distortion temperature of 60 ° C. and a melting point of 168 ° C., the difference is 108 ° C.
Polybenzimidazole has a heat distortion temperature of 410 ° C., a melting point of which is not clear, and a thermal decomposition temperature of 600 ° C. or higher.

Next, the selection of the thermoplastic resin used when actually forming the brake pad will be described.
The usage mode of the brake device described above is specifically a traveling pattern mainly assumed in the brake device in which the brake pad 20 is actually used.

Therefore, it is a temperature band of the brake temperature (hereinafter referred to as the brake temperature band) that frequently appears (used) when traveling in the assumed running pattern, and the brake pad 20 is in the brake temperature band. A suitable material will be selected.

Hereinafter, the brake temperature zone and the thermoplastic resin suitable for the brake temperature zone will be specifically described.

[2.1] When the frequency of use of the brake while driving in the city is relatively high When the frequency of use of the brake while driving in the city is relatively high, more specifically, in the case of driving in the city, for example, there are many downhill slopes. , Corresponds to the case where the brake is used relatively frequently.
In addition, the amount of wear debris produced increases in proportion to the brake temperature.

In this case, assuming that the frequency of brake use follows a normal distribution, the range of ± 1σ with respect to the standard deviation σ from the temperature at which the brake is used most frequently, which corresponds to the mean value, is out of the total number of brake uses. Approximately 68.3% of the number of uses is included, the range of ± 2σ includes approximately 95.5% of the total number of brakes used, and the range of ± 3σ includes the total number of brakes used. Approximately 99.7% of usages are included.
Therefore, the brake temperature band defined by the brake temperature at which the frequency of use becomes almost 0 corresponds to the range of approximately ± 3σ.

By the way, when the frequency of use of the brake during driving is relatively high in urban driving, the most frequently used temperature corresponding to the average value of the normal distribution = 250 ° C., and the brake temperature band corresponding to the range of approximately ± 3σ is It is a temperature range of 100 ° C to 400 ° C.

From this, the temperature corresponding to the standard deviation σ is (400-100) / 6 = 50 ° C., so the brake temperature band corresponding to the range of approximately ± 1σ is the temperature band of 200 ° C. to 300 ° C. The brake temperature band corresponding to the range of approximately ± 2σ is a temperature range of 150 ° C to 350 ° C.

In other words, it is in a softened state in the temperature range of ± 50 ° C. at least with respect to the most frequently used temperature = 250 ° C., and at least the temperature range corresponding to the heat distortion temperature to the melting point is 100 ° C. or higher, more preferably. If the temperature range corresponding to the heat distortion temperature to the melting point is 150 ° C. or higher and the thermoplastic resin is used, it is considered that the effect can be exhibited in the use of 68.3% or more of the brakes.

Further, in the selection of the thermoplastic resin, it is desired that the average temperature between the heat distortion temperature and the melting point is close to the temperature at which the brake device is most frequently used.

Considering these factors, it is considered that among the above-mentioned thermoplastic resins, the most suitable for the brake temperature band shown in FIG. 8 is the polyetheretherketone.

Therefore, by retaining the polyetheretherketone in the lining 22, the temperature zone in which the brake is used frequently in urban driving is the temperature between the heat distortion temperature and the melting point of the polyetheretherketone. They are almost the same, and it is possible to surely form a kneaded body or a group of kneaded bodies and suppress the scattering of the abrasion powder alone into the atmosphere.

[2.2] When the frequency of use of the brake while driving in the city is relatively low When the frequency of use of the brake while driving in the city is relatively low, more specifically, in the case of driving in the city, for example, there are many flat roads. , Corresponds to the case where the brake is used relatively infrequently.

When the brake is used relatively infrequently in city driving, the brake temperature is most often used at around 190 ° C, and the brake device is used more frequently in the brake temperature band = 130 ° C to 250 ° C. There is.

Therefore, assuming that the frequency of use of the brake follows a normal distribution, as in the case where the frequency of use of the brake during driving is relatively high in the above-mentioned city driving, the normal distribution is used when the frequency of use of the brake is relatively low in the city driving. The most frequently used temperature corresponding to the average value of is 190 ° C., and the temperature corresponding to the standard deviation σ is (280-100) / 6 = 30 ° C., so that the brake corresponds to a range of approximately ± 1σ. The temperature band is a temperature band of 160 ° C. to 220 ° C., and the brake temperature band corresponding to a range of approximately ± 2σ is a temperature band of 130 ° C. to 250 ° C.

Considering these factors, it is considered that the polyamide 6, polyamide 66 and polyphenylene sulfide are most suitable for the brake temperature zone shown in FIG. 9 among the above-mentioned thermoplastic resins. Here, the polyamide 6 and the polyamide 66 are so-called nylon 6 [registered trademark] and nylon 66 [registered trademark].

[2.3] In the case of a hybrid vehicle (HV) or an electric vehicle (EV) In a hybrid vehicle or an electric vehicle, the regenerative brake using an electric motor is controlled in coordination with the hydraulic brake, so that the brake is driven at a relatively high speed. If so, the braking force from the regenerative brake is used, and when the speed is relatively low, the braking force from the hydraulic brake is mainly used, and the frequency of use of the brake pad is relative to the case where the hydraulic brake is used alone. The brake temperature is relatively low.

In the case of a hybrid vehicle or an electric vehicle, the brake temperature is most frequently used at around 80 ° C., and the brake device is frequently used in the brake temperature range = 50 ° C. to 150 ° C.

Therefore, as in the case where the frequency of use of the brake during driving is relatively high in the above-mentioned city driving, assuming that the frequency of use of the brake follows a normal distribution, even in this case, as in the case of FIG. 8, the hybrid vehicle or Assuming that the frequency of use of the brakes in the case of an electric vehicle also follows a normal distribution, in the case of a hybrid vehicle or an electric vehicle, the most frequently used temperature corresponding to the mean value of the normal distribution is 80 ° C., and the standard deviation is σ. Since the corresponding temperature is (160-0) / 6 = 27 ° C., the brake temperature band corresponding to the range of approximately ± 1σ is the temperature band of 53 ° C. to 107 ° C., which corresponds to the range of approximately ± 2σ. The braking temperature band to be applied is a temperature range of 26 ° C to 134 ° C.

Considering these factors, it is considered that among the above-mentioned thermoplastic resins, non-modified polypropylene is most suitable for the brake temperature zone shown in FIG.

[2.4] In the case of high-load driving In the case of high-load driving, more specifically, the brakes are frequently used on long downhill slopes in mountainous areas, or the brakes are high due to sudden braking on highways. This corresponds to the case of load driving.

As shown in FIG. 11, in the case of high load driving, the brake temperature is most frequently used at around 500 ° C, and the brake device is frequently used in the brake temperature band = 400 ° C to 600 ° C. ing.

Therefore, assuming that the frequency of use of the brake follows a normal distribution even in the case of high load driving, as in the case of the above-mentioned case where the frequency of use of the brake during driving is relatively high, the most corresponding to the average value of the normal distribution. The frequently used temperature = 500 ° C., and the brake temperature band corresponding to the range of approximately ± 3σ is the temperature range of 400 ° C. to 600 ° C.

Therefore, among the above-mentioned thermoplastic resins, polybenzimidazole is considered to be the most suitable.

As described above, the thermoplastic resin mixed in the lining has a difference between the heat distortion temperature and the melting point of at least 100 degrees, so that the temperature distribution of the frequency of use of the brake follows a normal distribution. Assuming, the thermoplastic resin can maintain the softened state in the brake temperature range corresponding to the range of approximately ± 1σ with the temperature most frequently used as the average value, and the kneaded body or kneaded body is surely with respect to the friction powder. Flocks can be formed.

More preferably, by using a thermoplastic resin having a difference between the heat distortion temperature and the melting point of at least 150 degrees, the temperature range in which the softened state can be maintained is expanded and the kneaded body or kneaded body is more reliably used. Flocks can be formed.

In addition, by setting the heat distortion temperature of the thermoplastic resin to 50 degrees or more and the melting point to 400 degrees or less, it is possible to expand the options of the actual thermoplastic resin and facilitate the selection while surely forming the kneaded body. Is possible.

In the above description, the case of the floating type as the disc brake 1 has been described as an example, but the pistons as the pressing members are arranged facing each other, and the pistons arranged facing each other press the pair of brake pad pad assemblies against the disc rotor. The so-called opposed type (opposed piston type) having a configuration can be similarly applied.

In the above description, the lining of the brake pad used for the disc brake is made of non-fired ceramic friction material, and the lining is supported by the back plate to form the brake pad. However, the brake is not provided with the back plate. It is also possible to form it as a pad.

In the above description, the lining or brake pad used for the disc brake has been described, but it is also possible to form the brake shoe of the drum brake.

1 ... Disc brake, 2 ... Disc rotor, 3 ... Caliper, 11 ... Mounting, 12 ... Caliper body, 12a ... Cylinder part, 15 ... Piston, 20 ... Brake pad, 21 ... Back plate, 22 ... Lining, 30 ... Brake pad , 40 ... shim, 51 ... ceramic powder, 52 ... activated ceramic powder, 52a ... amorphous active layer, 54MTX ... matrix (base material), 54X ... ceramic particles, 54a ... precipitation layer, 54b ... adhesive layer , 60 ... Grinding material.

Claims (6)

Ceramic particles composed of at least one of silicic acid and silicate, and particles with an aerodynamic diameter of 2.5 μm or less are classified with a collection efficiency of 50% or less, and the remaining ceramic particles are adhered. A matrix that is solidified by adhering to each other via an agent layer,
Friction material composition and
Non-fired ceramic friction material with. The ceramic particles are ceramic particles in which particles having an aerodynamic diameter of 7.0 μm or less are collected with a collection efficiency of 50%.
The non-fired ceramic friction material according to claim 1. The non-fired ceramic friction material according to claim 1 or 2, wherein the adhesive layer contains a metal cation. A brake pad having a lining made of the non-fired ceramic friction material according to any one of claims 1 to 3. A classification process in which ceramic particles composed of at least one of silicic acid and silicate are classified and removed with an aerodynamic diameter of 2.5 μm or less with a collection efficiency of 50% or less.
A grinding process in which at least the surface of the ceramic particles remaining by the classification is activated by mechanochemical treatment, and
A mixing process of mixing the friction material composition with the ceramic particles whose surface has been activated, and
A kneading process in which an alkaline solution is added to a mixture of the ceramic particles and the friction material composition and kneaded to form a ceramic gel.
The defoaming process of obtaining a ceramic temporary molded product by molding while defoaming from the ceramic gel.
The solidification / drying process of solidifying and drying the ceramic temporary molded product at a predetermined temperature of 200 ° C. or lower to obtain a non-fired ceramic friction material.
A method for manufacturing a non-fired ceramic friction material. In the solidification / drying process, the ceramic temporary molded product is dried in a constant temperature furnace at a first temperature for a first predetermined time, and further, at a second temperature higher than the first temperature, longer than the first predetermined time. Dry for a second predetermined time,
The method for producing a non-fired ceramic friction material according to claim 5.

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