WO2015159642A1 - Brake piston, disc brake, method for manufacturing brake piston, and thermosetting resin composition - Google Patents

Abstract

This brake piston (100) is used in a disc brake and is provided with: a piston body (110) comprising a resin member (101); and metallic members (102). The piston body (110) has an opening (120). The metallic members (102) are provided so as to cover side end surfaces (125) of the opening (120) in the piston body (110). The side end surfaces (125) of the opening (120) in the piston body (110) and the metallic members (102) are joined, and the metallic members (102) have roughened layers comprising fine protrusions and recesses and provided on the joining surfaces (103) of the metallic members (102), the joining surfaces (103) being joined to at least the piston body (110). The side end surfaces (125) of the opening (120) in the piston body (110) and the metallic members (102) are joined because portions of the resin member (101) are present within the recesses which constitute the protrusions and recesses of the roughed layers.

Description

Brake piston, disc brake, method for producing brake piston, and thermosetting resin composition

The present invention relates to a brake piston, a disc brake, a method for manufacturing a brake piston, and a thermosetting resin composition.

In the case of brake pistons for disc brakes, resin-made brake pistons are being studied for the purpose of weight reduction.

For example, there are the following as conventional techniques related to a resin brake piston.
Patent Document 1 (Japanese Patent Laid-Open No. 8-93916) discloses a resin piston used for a disc brake, in which a metal reinforcing member is formed at least at a corner portion on the pressure receiving surface side of the brake fluid pressure of the resin piston. A resin-made piston is described.

In Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-148158), a metal cap that covers the outer peripheral surface, the inner peripheral surface, and the open end surface of the open end is integrated with the open end of the cup-shaped synthetic resin piston main body. The piston to be joined is described.

JP-A-8-93916 JP 2011-148158 A

However, according to the study of the present inventor, it has been clarified that the conventional resin brake piston has a oxidative deterioration of the piston surface due to heat damage, and the mechanical strength gradually decreases. Conventional resin brake pistons are excellent in terms of light weight, but there is still room for improvement in terms of reliability.

The present invention has been made in view of the above circumstances, and provides a brake piston excellent in performance balance between light weight and reliability.

According to the present invention,
A brake piston used for a disc brake,
A piston body having an opening and made of a resin member;
A metal member provided so as to cover the side end surface of the opening of the piston main body,
The side end face of the opening in the piston main body and the metal member are joined,
The metal member has a roughened layer composed of fine irregularities on at least a joint surface to be joined to the piston main body part,
The brake piston in which the side end face of the opening in the piston main body and the metal member are joined by the presence of a part of the resin member inside the concave portion constituting the concave and convex portions of the roughened layer. Provided.

Furthermore, according to the present invention,
A disc brake comprising the above brake piston is provided.

Furthermore, according to the present invention,
A manufacturing method for manufacturing the brake piston,
Preparing a metal member and a mold;
Disposing the metal member in the molding space of the mold; and
Filling the molding space with a thermosetting resin composition containing a thermosetting resin;
The resin member comprising the thermosetting resin composition and the metal member by curing the thermosetting resin composition in a state where at least a part of the thermosetting resin composition is in contact with the metal member. To obtain a brake piston,
A method for manufacturing a brake piston is provided.

Furthermore, according to the present invention,
A thermosetting resin composition used for forming the resin member constituting the brake piston,
A thermosetting resin composition including a thermosetting resin and a filler is provided.

According to the present invention, it is possible to provide a brake piston having an excellent performance balance between lightness and reliability.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

It is sectional drawing which shows an example of the structure of the brake piston of embodiment which concerns on this invention. It is a schematic diagram for demonstrating the example of the cross-sectional shape of the recessed part which comprises the roughening layer of the metal member surface of embodiment which concerns on this invention. It is sectional drawing which shows an example of the structure of the disc brake of embodiment which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar constituent elements are denoted by common reference numerals, and description thereof is omitted as appropriate. Unless otherwise specified, the numerical range “˜” represents the following from the above.

[Brake piston]
First, the brake piston according to the present embodiment will be described.
FIG. 1 is a cross-sectional view showing an example of the structure of a brake piston 100 according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining an example of the cross-sectional shape of the concave portion constituting the roughened layer on the surface of the metal member 102 according to the embodiment of the present invention.

The brake piston 100 according to the present embodiment is used for a disc brake, and includes a piston main body 110 made of a resin member 101 and a metal member 102. The piston main body 110 has an opening 120. The metal member 102 is provided so as to cover the side end face 125 of the opening 120 of the piston main body 110. Further, the side end surface 125 of the opening 120 in the piston main body 110 and the metal member 102 are joined, and the metal member 102 has a roughened layer made of fine irregularities on at least the joint surface 103 joined to the piston main body 110. Have. And the side end surface 125 of the opening part 120 in the piston main-body part 110 and the metal member 102 are joined because some resin members 101 exist in the inside of the recessed part 201 which comprises the said unevenness | corrugation of a roughening layer. .

The brake piston 100 according to the present embodiment is used for, for example, the disc brake 300 shown in FIG. FIG. 3 is a cross-sectional view showing an example of the structure of the disc brake 300 according to the embodiment of the present invention.
The disc brake 300 according to this embodiment includes a disc rotor 301, a brake pad 302, a hydraulic cylinder device 303, a caliper 304, a brake piston 100, and a seal 305. The disc brake 300 is mounted on a vehicle, for example.
The disk rotor 301 is connected to a rotating shaft (not shown). Brake pads 302 are provided on both sides of the disc rotor 301 to apply a frictional force to the disc rotor 301 by acting from both sides of the disc rotor 301 to act and react.
Further, the caliper 304 has a structure in which a hydraulic cylinder device 303 for pressing and driving the brake pad 302 is incorporated. The hydraulic cylinder device 303 incorporates the brake piston 100 according to the present embodiment.
A seal 305 is provided between the brake piston 100 and the hydraulic cylinder device 303.

Next, the operation of the disc brake 300 will be described. When the brake fluid is introduced into the hydraulic cylinder device 303, the brake fluid pressure in the hydraulic cylinder device 303 is increased, and thereby the brake piston 100 presses the brake pad 302. As a result, the brake pad 302 presses the disc rotor 301 to brake the rotating shaft.

The shape of the brake piston 100 according to the present embodiment is usually cylindrical or columnar.
In the brake piston 100 according to the present embodiment, the metal member 102 is provided at a position facing the brake pad 302. That is, in the brake piston 100 according to the present embodiment, the metal member 102 is provided on a surface that presses the brake pad 302. Thereby, it can be suppressed that the surface of the piston main body 110 made of the resin member 101 is oxidized and deteriorated due to heat damage from the brake pad 302 side, and the mechanical strength is gradually lowered.

The brake piston 100 has a linear expansion coefficient α _R in the range from 25 ° C. of the resin member 101 to the glass transition temperature, and a linear expansion coefficient α _M in the range from 25 ° C. of the metal member 102 to the glass transition temperature of the resin member 101. The absolute value of the difference (α _R −α _M ) is preferably 10 ppm / ° C. or less, more preferably 5 ppm / ° C. or less. If the difference in the linear expansion coefficient is not more than the above upper limit value, the thermal stress due to the difference in linear expansion that occurs when the brake piston 100 is exposed to a high temperature can be further suppressed. That is, if the difference in the linear expansion coefficient is not more than the upper limit value, the dimensional stability of the brake piston 100 at a high temperature can be further improved.
In the present embodiment, when the linear expansion coefficient has anisotropy, an average value thereof is represented. For example, when the resin member 101 is in the form of a sheet, when the linear expansion coefficient in the flow direction (MD) is different from the linear expansion coefficient in the vertical direction (TD), the average value thereof is the linear expansion coefficient α of the resin member 101. _R.

The brake piston 100 is not particularly limited, but it is preferable that the side end face 125 of the opening 120 in the piston main body 110 and the metal member 102 are joined without an adhesive. The resin member 101 and the metal member 102 have excellent bonding strength even without an adhesive. Therefore, the manufacturing process of the brake piston 100 can be simplified.

In the brake piston 100, it is preferable that a part of the filler (B) to be described later is present inside the concave portion 201 that constitutes the concave and convex portions of the roughened layer. Thereby, the mechanical strength of the area | region where the resin member 101 and the metal member 102 penetrate | invaded mutually can be improved further.

The average major axis by image analysis of the electron micrograph of the filler (B) present in the recess 201 is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 4.0 μm or less. . Thereby, the mechanical strength of the area | region where the resin member 101 and the metal member 102 penetrate | invaded mutually can be improved further.

Further, the average aspect ratio of the filler (B) existing inside the recess 201 is preferably 1 or more and 50 or less, more preferably 1 or more and 40 or less.

The average major axis and average aspect ratio of the filler (B) present in the recess 201 can be measured from the SEM photograph as follows. First, a cross section of the roughened layer is photographed with a scanning electron microscope. From the observation image, 50 fillers (B) existing inside the recess 201 are arbitrarily selected, and their major diameters (fiber length in the case of fibrous fillers, and major axis in the planar direction in the case of plate-like fillers). Dimension) and a short diameter (in the case of a fibrous filler, the fiber diameter, in the case of a plate-like filler, the dimension in the thickness direction) are measured. The average major axis is obtained by integrating all major axes and dividing by the number. Similarly, the average minor axis is obtained by integrating all minor axes and dividing by the number. The average major axis with respect to the average minor axis is defined as the average aspect ratio.

The filler (B) present in the recess 201 is a group consisting of wollastonite, kaolin clay, talc, calcium carbonate, zinc oxide, calcium silicate hydrate, aluminum borate whisker, and potassium titanate fiber. It is preferable that it is 1 type, or 2 or more types chosen from.

Next, the operation and effect of this embodiment will be described. The brake piston 100 according to the present embodiment is provided with a metal member 102 at a position facing the brake pad 302. Thereby, it can be suppressed that the surface of the piston main body 110 made of the resin member 101 is oxidized and deteriorated due to heat damage from the brake pad 302 side, and the mechanical strength is gradually lowered.
Furthermore, the brake piston 100 according to the present embodiment has a side end face 125 of the opening 120 in the piston main body 110 due to the presence of a part of the resin member 101 inside the recess 201 that forms the unevenness of the roughened layer. And the metal member 102 are joined. Thereby, even if it exposes to high temperature for a long time, the joining strength of piston main-body part 110 and metal member 102 can be maintained. As a result, it is possible to further suppress the deterioration of the mechanical strength due to the oxidative deterioration of the surface of the piston main body 110 made of the resin member 101 due to the heat damage from the brake pad 302 side.
Moreover, since the piston main body part 110 consists of the resin member 101, the brake piston 100 which concerns on this embodiment can be reduced in weight compared with the brake piston which consists only of the same kind of metal, maintaining required intensity | strength. Thus, for example, an energy-saving vehicle can be realized when mounted on a vehicle.
From the above, according to this embodiment, it is possible to provide the brake piston 100 that is excellent in the performance balance between lightness and reliability.

<Resin member>
Hereinafter, the resin member 101 according to the present embodiment will be described.
The resin member 101 is formed, for example, by curing a thermosetting resin composition (P) including a thermosetting resin (A) and a filler (B).

Examples of the thermosetting resin (A) include phenol resin, epoxy resin, unsaturated polyester resin, diallyl phthalate resin, melamine resin, oxetane resin, maleimide resin, urea (urea) resin, polyurethane resin, silicone resin, and benzoxazine. A resin having a ring, a cyanate ester resin, or the like is used. These may be used alone or in combination of two or more.
Among these, phenol resins that are excellent in heat resistance, workability, mechanical properties, electrical properties, adhesion, and wear resistance are preferably used.
The content of the thermosetting resin (A) is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 30% by mass or less, when the entire resin member 101 is 100% by mass. is there.

Examples of the phenol resin include novolak phenol resins such as phenol novolak resin, cresol novolak resin, and bisphenol A type novolak resin; Examples thereof include resol type phenol resins such as oil-melted resol phenol resin; aryl alkylene type phenol resins and the like. These may be used alone or in combination of two or more.
Among these, a novolak type phenol resin is preferable because it is easily available, inexpensive, and has good workability by roll kneading.

In the above phenol resin, when a novolac type phenol resin is used, hexamethylenetetramine is usually used as a curing agent. Although hexamethylenetetramine is not particularly limited, it is preferably used in an amount of 10 to 25 parts by weight, more preferably 13 to 20 parts by weight, based on 100 parts by weight of the novolac type phenol resin. When the amount of hexamethylenetetramine used is not less than the above lower limit, the curing time during molding can be shortened. Moreover, the external appearance of the brake piston 100 obtained can be improved as the usage-amount of hexamethylenetetramine is below the said upper limit.

From the viewpoint of improving the mechanical strength of the resin member 101, the thermosetting resin composition (P) preferably contains a filler (B). However, in this embodiment, the elastomer (D) described later is excluded from the filler (B).
The content of the filler (B) is preferably 50% by mass or more and 90% by mass or less, and more preferably 60% by mass or more and 80% by mass or less when the entire resin member 101 is 100% by mass. By making the content of the filler (B) within the above range, it is possible to further improve the mechanical strength of the obtained resin member 101 while improving the workability of the thermosetting resin composition (P). it can. Thereby, it is possible to obtain a brake piston 100 that is more excellent in the bonding strength between the resin member 101 and the metal member 102. Further, by adjusting the type and content of the filler (B), it is possible to adjust the value or the like of the linear expansion coefficient alpha _R of the resin member 101 to be obtained.

Examples of the filler (B) include a fibrous filler, a granular filler, and a plate-like filler. Here, the fibrous filler is a filler whose shape is fibrous. The plate-like filler is a filler whose shape is plate-like. The granular filler is a filler having a shape other than a fiber or plate including an indefinite shape.

Examples of the fibrous filler include glass fiber, carbon fiber, asbestos fiber, metal fiber, wollastonite, attapulgite, sepiolite, rock wool, aluminum borate whisker, potassium titanate fiber, calcium carbonate whisker, and titanium oxide whisker. And fibrous inorganic fillers such as ceramic fibers; and fibrous organic fillers such as aramid fibers, polyimide fibers, and polyparaphenylene benzobisoxazole fibers. These may be used alone or in combination of two or more.

Examples of the plate-like filler and granular filler include talc, kaolin clay, calcium carbonate, zinc oxide, calcium silicate hydrate, mica, glass flakes, glass powder, magnesium carbonate, silica, titanium oxide, Alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, aluminum borate, calcium borate, sodium borate, aluminum nitride, boron nitride, silicon nitride, the above fibers For example, a pulverized product of a filler. These may be used alone or in combination of two or more.

The filler (B) is 1 filler (B1) having an average particle diameter of more than 5 μm in the weight-based particle size distribution measured by the laser diffraction / scattering particle size distribution measurement method when the total amount of the filler (B) is 100% by mass. It is preferable that the content is from 100% by mass to 100% by mass, and more preferably from 2% by mass to 98% by mass. Thereby, the mechanical strength of the resin member 101 obtained can be further improved while improving the workability of the thermosetting resin composition (P). Although the upper limit of the average particle diameter of a filler (B1) is not specifically limited, For example, it is 100 micrometers or less.
More preferably, the filler (B1) includes a fibrous filler or a plate-like filler having an average major axis of 5 μm to 50 mm and an average aspect ratio of 1 to 1000.
The average major axis and average aspect ratio of the filler (B1) can be measured from an SEM photograph as follows, for example. First, a plurality of fibrous fillers or plate-like fillers are photographed with a scanning electron microscope. From the observation image, 50 fibrous fillers or plate-like fillers are arbitrarily selected, and their major diameters (fiber length in the case of fibrous fillers, planar major dimension in the case of plate-like fillers) and The short diameter (in the case of a fibrous filler, the fiber diameter, in the case of a plate-like filler, the dimension in the thickness direction) is measured. The average major axis is obtained by integrating all major axes and dividing by the number. Similarly, the average minor axis is obtained by integrating all minor axes and dividing by the number. The average major axis with respect to the average minor axis is defined as the average aspect ratio.

The filler (B1) is preferably one or more selected from wollastonite, glass fiber, carbon fiber, glass bead, calcium carbonate and the like. When such a filler (B1) is used, the mechanical strength of the resin member 101 can be particularly improved.

In addition, the filler (B) has an average particle size of 0.1 μm or more and 5 μm or less in a weight-based particle size distribution measured by a laser diffraction / scattering particle size distribution measurement method when the total amount of the filler (B) is 100% by mass. The filler (B2) is preferably contained in an amount of 0% by mass to 99% by mass, and more preferably 2% by mass to 98% by mass. Thereby, the filler (B) can be sufficiently present inside the recess 201. As a result, the mechanical strength of the region where the resin member 101 and the metal member 102 have entered each other can be further improved.
As the filler (B2), the average major axis is preferably 0.1 μm or more and 100 μm or less, more preferably 0.2 μm or more and 50 μm or less, and the average aspect ratio is preferably 1 or more and 50 or less, more preferably 1 or more and 40 or less. It is more preferable to include a fibrous filler or a plate-like filler.
The average major axis and average aspect ratio of the filler (B2) can be measured from an SEM photograph as follows, for example. First, a plurality of fibrous fillers or plate-like fillers are photographed with a scanning electron microscope. From the observation image, 50 fibrous fillers or plate-like fillers are arbitrarily selected, and their major diameters (fiber length in the case of fibrous fillers, planar major dimension in the case of plate-like fillers) and The short diameter (in the case of a fibrous filler, the fiber diameter, in the case of a plate-like filler, the dimension in the thickness direction) is measured. The average major axis is obtained by integrating all major axes and dividing by the number. Similarly, the average minor axis is obtained by integrating all minor axes and dividing by the number. The average major axis with respect to the average minor axis is defined as the average aspect ratio.

As such a filler (B2), one type selected from wollastonite, kaolin clay, talc, calcium carbonate, zinc oxide, calcium silicate hydrate, aluminum borate whisker, and potassium titanate fiber or Two or more are preferred.

Further, the filler (B) may be subjected to a surface treatment with a coupling agent such as a silane coupling agent (C) described later.

The thermosetting resin composition (P) may further contain a silane coupling agent (C). By including the silane coupling agent (C), the adhesion between the resin member 101 and the metal member 102 can be improved. Further, by including the silane coupling agent (C), the affinity between the thermosetting resin (A) and the filler (B) is improved, and as a result, the mechanical strength of the resin member 101 is further improved. be able to.

The content of the silane coupling agent (C) is not particularly limited because it depends on the specific surface area of the filler (B), but is preferably 0.01 parts by mass or more and 4 parts by mass with respect to 100 parts by mass of the filler (B). 0.0 part by mass or less, and more preferably 0.1 part by mass or more and 1.0 part by mass or less. When the content of the silane coupling agent (C) is within the above range, the mechanical strength of the resin member 101 can be further improved while sufficiently covering the filler (B).

Examples of the silane coupling agent (C) include epoxy groups such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. -Containing alkoxysilane compounds; mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane; γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2- Ureido group-containing alkoxysilane compounds such as ureidoethyl) aminopropyltrimethoxysilane; γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxy Isocyanato group-containing alkoxysilane compounds such as silane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, γ-isocyanatopropyltrichlorosilane; γ-amino Amino group-containing alkoxysilane compounds such as propyltriethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane; And hydroxyl group-containing alkoxysilane compounds such as -hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane.
These may be used alone or in combination of two or more.

The manufacturing method of a thermosetting resin composition (P) is not specifically limited, Generally, it can manufacture by a well-known method. For example, the following method is mentioned. First, thermosetting resin (A), if necessary, filler (B), silane coupling agent (C), elastomer (D), curing agent, curing aid, release agent, pigment, flame retardant, weather resistance An agent, an antioxidant, a plasticizer, a lubricant, a sliding agent, a foaming agent and the like are blended and mixed uniformly. Next, the obtained mixture is heated and melt-kneaded by a kneading apparatus such as a roll, a kneader, a twin-screw extruder alone, or a combination of a roll and another kneading apparatus. Finally, the thermosetting resin composition (P) is obtained by granulating or pulverizing the obtained mixture.

The linear expansion coefficient α _R in the range from 25 ° C. to the glass transition temperature of the resin member 101 is preferably 10 ppm / ° C. or more and 35 ppm / ° C. or less, more preferably 10 ppm / ° C. or more and 25 ppm / ° C. or less. When the linear expansion coefficient α _R is within the above range, the reliability of the brake piston 100 can be further improved.

<Metal member>
Hereinafter, the metal member 102 will be described.

From the viewpoint of improving the bonding strength between the piston main body 110 and the metal member 102, the metal member 102 has a roughened layer made of fine irregularities on the bonding surface 103 of the metal member 102 with the piston main body 110. . Here, the roughened layer refers to a region having a plurality of recesses 201 provided on the surface of the metal member 102.

The thickness of the roughened layer is preferably 3 μm or more and 40 μm or less, more preferably 4 μm or more and 32 μm or less, and particularly preferably 4 μm or more and 30 μm or less. When the thickness of the roughened layer is within the above range, the bonding strength between the piston main body 110 and the metal member 102 can be further improved. Here, in this embodiment, the thickness of the roughened layer represents the depth D3 of the largest depth among the plurality of recesses 201, and can be calculated from an electron microscope (SEM) photograph.

It is preferable that the cross section of the recess 201 has a shape having a cross section width D2 larger than the cross section width D1 of the opening 203 in at least a part between the opening 203 and the bottom 205 of the recess 201.
As shown in FIG. 2, the cross-sectional shape of the recess 201 is not particularly limited as long as D2 is larger than D1, and can take various shapes. The cross-sectional shape of the recess 201 can be observed with, for example, an electron microscope (SEM).

If the cross-sectional shape of the recess 201 is the above-mentioned shape, the reason why the brake piston 100 with better bonding strength can be obtained is not necessarily clear, but the surface of the bonding surface 103 is between the resin member 101 and the metal member 102. This is thought to be because the anchor effect is even stronger.
When the cross-sectional shape of the concave portion 201 is the above shape, the resin member 101 is caught between the opening 203 and the bottom portion 205 of the concave portion 201, so that the anchor effect works effectively. Therefore, it is considered that the bonding strength between the piston main body 110 and the metal member 102 is improved.

The average depth of the recess 201 is preferably 0.5 μm or more and 40 μm or less, and more preferably 1 μm or more and 30 μm or less. When the average depth of the recess 201 is equal to or less than the above upper limit value, the thermosetting resin composition (P) can sufficiently enter the depth of the recess 201, so that the resin member 101 and the metal member 102 enter each other. The mechanical strength of the region thus obtained can be further improved. Since the ratio of the filler (B) existing inside the recess 201 can be increased when the average depth of the recess 201 is equal to or more than the above lower limit value, the region where the resin member 101 and the metal member 102 have entered each other The mechanical strength of can be improved. Therefore, when the average depth of the recess 201 is within the above range, the bonding strength between the piston main body 110 and the metal member 102 can be further improved.
The average depth of the recess 201 can be measured from a scanning electron microscope (SEM) photograph as follows, for example. First, a cross section of the roughened layer is photographed with a scanning electron microscope. From the observation image, 50 concave portions 201 are arbitrarily selected and their depths are measured. The average depth is obtained by integrating all the depths of the recesses 201 and dividing the sum by the number.

The average cross-sectional width of the opening 203 of the recess 201 is preferably 2 μm or more and 60 μm or less, more preferably 3 μm or more and 50 μm or less, and further preferably 3 μm or more and 30 μm or less. When the average cross-sectional width of the opening 203 is not more than the above upper limit value, the anchor effect between the resin member 101 and the metal member 102 can be expressed more strongly. When the average cross-sectional width of the opening 203 is equal to or greater than the above lower limit value, the ratio of the filler (B) present in the recess 201 can be increased, so that the joint surface between the piston main body 110 and the metal member 102 can be increased. The strength of the resin member 101 can be improved. Therefore, when the average cross-sectional width of the opening 203 is within the above range, the bonding strength between the piston main body 110 and the metal member 102 can be further improved.
The average cross-sectional width of the opening 203 can be measured from an SEM photograph as follows, for example. First, a cross section of the roughened layer is photographed with a scanning electron microscope. From the observation image, 50 concave portions 201 are arbitrarily selected, and their cross-sectional widths D1 are measured. The average cross-sectional width is obtained by integrating all the cross-sectional widths D1 of the openings 203 and dividing the sum by the number.

The surface roughness Ra of the bonding surface 103 of the metal member 102 is preferably 0.5 μm or more and 40.0 μm or less, more preferably 1.0 μm or more and 20.0 μm or less, and particularly preferably 1.0 μm or more and 10. 0 μm or less. When the surface roughness Ra is within the above range, the bonding strength between the piston main body 110 and the metal member 102 can be further improved.
Further, the maximum height Rz of the joint surface 103 of the metal member 102 is preferably 1.0 μm or more and 40.0 μm or less, and more preferably 3.0 μm or more and 30.0 μm or less. When the maximum height Rz is within the above range, the bonding strength between the piston main body 110 and the metal member 102 can be further improved. Ra and Rz can be measured according to JIS-B0601.

The ratio of the actual surface area by the nitrogen adsorption BET method to the apparent surface area of the joining surface 103 at least joined to the piston main body 110 (hereinafter also simply referred to as a specific surface area) is preferably 100 or more. Is 150 or more. When the specific surface area is equal to or greater than the lower limit, the bonding strength between the piston main body 110 and the metal member 102 can be further improved. The specific surface area is preferably 400 or less, more preferably 380 or less, and particularly preferably 300 or less. When the specific surface area is less than or equal to the upper limit, the bonding strength between the piston main body 110 and the metal member 102 can be further improved.

Here, the apparent surface area in the present embodiment means a surface area when it is assumed that the surface of the metal member 102 is smooth without unevenness. For example, when the surface shape is a rectangle, it is represented by vertical length × horizontal length. On the other hand, the actual surface area by the nitrogen adsorption BET method in the present embodiment means the BET surface area obtained from the adsorption amount of nitrogen gas. For example, using a specific surface area / pore distribution measurement device (BELSORPmini II, manufactured by Nippon Bell Co., Ltd.) for a vacuum dried sample to be measured, the nitrogen adsorption / desorption amount at liquid nitrogen temperature is measured, and based on the nitrogen adsorption / desorption amount Can be calculated.
When the specific surface area is within the above range, it is not always clear why the brake piston 100 having further excellent bonding strength can be obtained. However, the surface of the bonding surface 103 with the piston main body 110 is formed between the resin member 101 and the metal. This is considered to be because the anchor effect with the member 102 can be expressed more strongly.
When the specific surface area is equal to or greater than the lower limit, the contact area between the resin member 101 and the metal member 102 is increased, and the region where the resin member 101 and the metal member 102 enter each other increases. As a result, it is considered that the area where the anchor effect works increases and the bonding strength between the piston main body 110 and the metal member 102 is further improved.
On the other hand, if the specific surface area is too large, the proportion of the metal member 102 in the region where the resin member 101 and the metal member 102 have entered each other decreases, and the mechanical strength of this region is reduced. Therefore, when the specific surface area is equal to or less than the upper limit value, the mechanical strength of the region where the resin member 101 and the metal member 102 enter each other is further improved. As a result, the piston main body 110 and the metal member 102 It is considered that the bonding strength of the steel can be further improved.
From the above, when the specific surface area is within the above range, the surface of the joint surface 103 with the resin member 101 can exhibit the anchor effect between the resin member 101 and the metal member 102 even more strongly. It is inferred that

The metal member 102 is not particularly limited, but at least the glossiness of the joint surface 103 joined to the piston main body 110 is preferably 0.1 or more, more preferably 0.5 or more, and further preferably 1 or more. It is. When the glossiness is equal to or higher than the lower limit, the bonding strength between the piston main body 110 and the metal member 102 can be further improved. Further, the glossiness is preferably 30 or less, more preferably 20 or less. When the glossiness is less than or equal to the upper limit value, the bonding strength between the piston main body 110 and the metal member 102 can be further improved. Here, the glossiness in the present embodiment indicates a value at a measurement angle of 60 ° measured in accordance with ASTM-D523. The glossiness can be measured using, for example, a digital glossiness meter (20 °, 60 °) (GM-26 type, manufactured by Murakami Color Research Laboratory).
When the glossiness is within the above range, the reason why the brake piston 100 that is more excellent in the bonding strength is not necessarily clear, but the surface of the bonding surface 103 with the piston main body 110 has a more messy structure, This is probably because the anchor effect between the resin member 101 and the metal member 102 can be expressed more strongly.

The metal material constituting the metal member 102 is not particularly limited, and examples thereof include iron, stainless steel, aluminum, aluminum alloy, magnesium, magnesium alloy, copper, and copper alloy from the viewpoint of availability and price. These may be used alone or in combination of two or more. Among these, stainless steel is preferable from the viewpoint of corrosion resistance and high strength.

Next, a method for forming a roughened layer on the surface of the metal member 102 will be described.
The roughened layer can be formed, for example, by chemically treating the surface of the metal member 102 using a surface treatment agent.
Here, the chemical treatment of the surface of the metal member 102 using the surface treatment agent itself has been performed in the prior art. However, the present inventors consider factors such as (1) the combination of the metal member and the surface treatment agent, (2) the temperature and time of the chemical treatment, and (3) the post-treatment of the surface of the metal member after the chemical treatment. It has been found that a roughened layer capable of further improving the bonding strength between the piston main body 110 and the metal member 102 can be obtained by performing a high degree of control. In order to obtain a roughened layer that can further improve the bonding strength between the piston main body 110 and the metal member 102, it is particularly important to control these factors to a high degree.
Hereinafter, an example of a method for forming a roughened layer on the surface of the metal member 102 will be described. However, the formation method of the roughening layer which concerns on this embodiment is not limited to the following examples.

First, (1) a combination of a metal member and a surface treatment agent is selected.
When a metal member composed of iron or stainless steel is used, it is preferable to select an aqueous solution in which an inorganic acid, a chlorine ion source, a cupric ion source, and a thiol compound are combined as necessary as a surface treatment agent.
When a metal member composed of aluminum or an aluminum alloy is used, it is preferable to select an aqueous solution in which an alkali source, an amphoteric metal ion source, a nitrate ion source, and a thio compound are combined as necessary as a surface treatment agent.
When a metal member composed of magnesium or a magnesium alloy is used, an alkali source is used as the surface treatment agent, and it is particularly preferable to select an aqueous solution of sodium hydroxide.
When using a metal member composed of copper or a copper alloy, as a surface treatment agent, an inorganic acid such as nitric acid or sulfuric acid, an organic acid such as an unsaturated carboxylic acid, a persulfate, hydrogen peroxide, an imidazole, or a derivative thereof, Tetrazole and its derivatives, aminotetrazole and its derivatives, azoles such as aminotriazole and its derivatives, pyridine derivatives, triazine, triazine derivatives, alkanolamines, alkylamine derivatives, polyalkylene glycol, sugar alcohol, cupric ion source, chlorine It is preferable to select an aqueous solution using at least one selected from an ion source, a phosphonic acid chelating agent, an oxidizing agent, and N, N-bis (2-hydroxyethyl) -N-cyclohexylamine.

Next, (2) the metal member is immersed in a surface treatment agent, and the surface of the metal member is chemically treated. At this time, the processing temperature is, for example, 30 ° C. The treatment time is appropriately determined depending on the material and surface state of the metal member to be selected, the type and concentration of the surface treatment agent, the treatment temperature, etc., and is, for example, 30 to 300 seconds. At this time, it is important that the etching amount of the metal member in the depth direction is preferably 3 μm or more, more preferably 5 μm or more. The etching amount in the depth direction of the metal member can be evaluated by calculating from the weight, specific gravity and surface area of the dissolved metal member. The etching amount in the depth direction can be adjusted by the type and concentration of the surface treatment agent, the treatment temperature, the treatment time, and the like.
In this embodiment, by adjusting the etching amount in the depth direction, the thickness of the roughened layer, the average depth of the recesses 201, the specific surface area, the glossiness, Ra, Rz, and the like can be adjusted.

Finally, (3) post-treatment is performed on the surface of the metal member after chemical treatment. First, the metal member surface is washed with water and dried. Next, the chemically treated metal member surface is treated with an aqueous nitric acid solution or the like.
Through the above procedure, the metal member 102 having the roughened layer according to the present embodiment can be obtained.

[Brake piston manufacturing method]
Next, a method for manufacturing the brake piston 100 will be described. Although it does not specifically limit as a manufacturing method of the brake piston 100, For example, the injection molding method, the transfer molding method, the compression molding method, the injection compression molding method etc. are mentioned. Among these, the injection molding method and the compression molding method are particularly suitable.

The manufacturing method of the brake piston 100 according to the present embodiment includes, for example, the following steps.

First, a metal member 102 and a mold are prepared. As the metal member 102, it is preferable to prepare the metal member 102 in which at least a portion to be joined to the piston main body 110 is roughened from the viewpoint of improving adhesion and durability.

Next, the metal member 102 is placed in the molding space of the mold.
Next, the inside of the molding space is filled with the fluidized thermosetting resin composition (P) using, for example, an injection molding machine. Subsequently, by curing the thermosetting resin composition (P) in a state where at least a part of the thermosetting resin composition (P) is in contact with the metal member 102, the thermosetting resin composition (P) can be cured. The resin member 101 and the metal member 102 are joined. From the above, the brake piston 100 is obtained.

The thermosetting resin composition (P) preferably has high fluidity in order to perform molding well. Therefore, the thermosetting resin composition (P) has a melt viscosity at 175 ° C. of preferably 10 Pa · s to 3000 Pa · s, and more preferably 30 Pa · s to 2000 Pa · s. The melt viscosity at 175 ° C. can be measured by, for example, a thermal fluidity evaluation apparatus (flow tester) manufactured by Shimadzu Corporation.

In order to realize the thermosetting resin composition (P) having such a viscosity behavior, for example, the type and amount of the thermosetting resin (A) described above, the type and amount of the filler (B), an elastomer, What is necessary is just to adjust the kind and quantity of (D) suitably.

In the method of manufacturing the brake piston 100 according to the present embodiment, in the step of filling the molding space with the fluidized thermosetting resin composition (P), the metal member is caused by the flow pressure of the thermosetting resin composition (P). It is preferable to fill the molding space with the thermosetting resin composition (P) while pressing 102 against the molding surface of the mold. By doing so, it is possible to obtain a brake piston 100 of good quality that suppresses the generation of burrs and has excellent adhesion between the metal member 102 and the piston main body 110.

In the present embodiment, the molding conditions of the brake piston 100 are not particularly limited because they vary depending on the molding method employed, but generally known molding conditions in the employed molding method can be employed. When a compression molding method is used as the molding method, for example, molding conditions of a temperature of 150 to 180 ° C., a pressure of 5 to 30 MPa, and a curing time of 30 seconds to 5 minutes can be mentioned.

As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and various structures other than the above can also be employ | adopted.

Hereinafter, the present embodiment will be described in detail with reference to examples and comparative examples. In addition, this embodiment is not limited to description of these Examples at all.

Example 1
<Preparation of thermosetting resin composition (P1)>
20.0% by mass of novolak-type phenolic resin (PR-51305, manufactured by Sumitomo Bakelite Co., Ltd.), 3.0% by mass of hexamethylenetetramine, glass fiber A (CS3E479, manufactured by Nittobo Co., Ltd., average particle size: 11 μm, average major axis) : 3 mm, average aspect ratio: 270) 3.0% by mass, Wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm) 55.0% by mass, calcined clay (Imelice) 16.0% by mass, Pole Star 501, average particle size: 0.6 μm), 1.0% by mass of magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.), and 2.0% by mass of other components such as a lubricant %, Each is dry-mixed, melted and kneaded with a heating roll at 90 ° C., crushed and cooled to a granular thermosetting resin It was obtained Narubutsu (P1).

<Surface treatment of metal members>
First, a stainless steel sheet A (80 mm × 10 mm, thickness 1.0 mm, density 7.93 g / cm ³ , thermal conductivity 16.7 W / (m · K), SUS304) not subjected to surface treatment was prepared. Further, an aqueous solution of sulfuric acid (50% by mass), cupric sulfate pentahydrate (3% by mass), potassium chloride (3% by mass), and thiosalicylic acid (0.0001% by mass) was prepared. And in the obtained aqueous solution (30 degreeC), the stainless steel sheet A was immersed and rock | fluctuated, and 15 micrometers (calculated from the weight which stainless steel decreased) was dissolved in the depth direction. Subsequently, it washed with water and dried and the stainless steel sheet 1 was obtained.

<Evaluation method of metal member>
(Measurement of surface roughness of metal parts)
The surface shape of the joint surface between the metal member and the resin member at a magnification of 20 was measured using an ultra-deep shape measuring microscope (VK9700 manufactured by Keyence Corporation). As for the surface roughness, Ra and Rz were measured. Ra and Rz were measured according to JIS-B0601.
The stainless sheet 1 had an Ra of 2.5 μm and an Rz of 15.3 μm.

(Measurement of specific surface area)
The sample to be measured was vacuum-dried at 120 ° C. for 6 hours, and then the nitrogen adsorption / desorption amount at the liquid nitrogen temperature was measured using an automatic specific surface area / pore distribution measuring device (BELSORPmini II, manufactured by Nippon Bell Co., Ltd.). The actual surface area by the nitrogen adsorption BET method was calculated from the BET plot. The specific surface area was calculated by dividing the actual surface area measured by the nitrogen adsorption BET method by the apparent surface area.
The specific surface area of the stainless steel sheet 1 was 250.

(Measurement of surface gloss of metal parts)
The glossiness of the surface of the metal member is measured at 60 ° in accordance with ASTM-D523 using a digital gloss meter (20 °, 60 °) (GM-26, manufactured by Murakami Color Research Laboratory Co., Ltd.). It was measured.
The glossiness of the stainless steel sheet 1 was 10.

(Observation of the surface of metal members)
The surface of the metal member was photographed with an electron microscope (SEM), and the structure of the roughened layer existing on the surface of the metal member was observed. From this observed image, the thickness of the roughened layer, the cross-sectional shape of the recess, the average depth of the recess, and the average cross-sectional width of the opening were determined.
The thickness of the roughened layer of the stainless steel sheet 1 was 15 μm, the average depth of the recesses was 13 μm, and the average cross-sectional width of the openings was 14 μm. Further, as shown in FIG. 2, the cross section of the concave portion has a shape having a cross sectional width larger than the cross sectional width of the opening portion in at least a part from the opening portion to the bottom portion of the concave portion.

(Measurement of linear expansion coefficient α _M )
The linear expansion coefficient α _M in the range from 25 ° C. to the glass transition temperature of the resin member was measured under a compression condition of 5 ° C./min using a thermomechanical analyzer TMA (manufactured by TA Instruments, EXSTAR6000). The linear expansion coefficient α _M of the stainless steel sheet 1 was 17 ppm / ° C.

<Production of metal resin composite>
A metal resin composite 1 was produced using the obtained thermosetting resin composition (P1) and the stainless steel sheet 1. Specifically, it was produced by the following procedure.
First, the stainless steel sheet 1 having a thickness of 1 mm was placed in the mold without being fixed. Next, the thermosetting resin composition (P1) was heated so that the thickness after curing was 3 mm, and a predetermined amount was injected into the mold. At this time, the stainless steel sheet 1 was pressed against the inner wall of the mold by the fluid pressure of the thermosetting resin composition (P1). Finally, the thermosetting resin composition (P1) was cured by compression molding to obtain a metal resin composite 1 that was a two-layer sheet of a resin member sheet having a thickness of 3 mm and a stainless sheet 1 having a thickness of 1 mm. This metal resin composite 1 was used as a test piece 1. The compression molding conditions were an effective pressure of 20 MPa, a mold temperature of 175 ° C., and a curing time of 3 minutes.

(Observation of joint surface of metal resin composite)
The cross section of the joint surface of the metal resin composite 1 was photographed with an electron microscope (SEM), and the structure of the cross section of the joint surface was observed. From this observed image, the presence or absence of a filler inside the recess was determined. The presence or absence of a filler inside the recess was also confirmed from energy dispersive X-ray fluorescence analysis.

(Measurement of linear expansion coefficient α _R )
Using a thermomechanical analyzer TMA (manufactured by TA Instruments, EXSTAR6000), the linear expansion coefficient α _R in the range from 25 ° C. to the glass transition temperature of the resin member sheet was measured under compression conditions of 5 ° C./min. The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P1) was 15 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 2 ppm / ° C.

(Bending strength retention)
The obtained test piece 1 was stored in a 350 ° C. atmosphere for 100 hours. At this time, the stainless steel sheet 1 was placed on the upper side and stored.
The bending strength of the test pieces before and after storage was measured in an atmosphere of 25 ° C. according to JIS K 6911, and the bending strength retention rate was calculated. At this time, the test was performed with the stainless steel sheet 1 placed on the lower side.

(Reliability evaluation of brake piston)
First, a brake piston shown in FIG. 1 was produced under the same conditions as those for producing the test piece 1. Next, the obtained brake piston was housed in a caliper, and stored for 100 hours while the metal member was in contact with the hot plate at 350 ° C. Thereafter, the presence or absence of peeling of the metal member was examined.
The evaluation criteria are as follows.
◯: No separation was observed between the piston main body and the metal member. ×: Partial separation was observed between the piston main body and the metal member, or bulge was observed on the surface of the piston main body.

(Example 2)
A metal resin composite 2 was produced in the same manner as in Example 1 except that the following thermosetting resin composition (P2) was used instead of the thermosetting resin composition (P1). This metal resin composite 2 was used as a test piece 2, and the same evaluation as in Example 1 was performed.
20.0% by mass of novolak-type phenolic resin (PR-51305, manufactured by Sumitomo Bakelite Co., Ltd.), 3.0% by mass of hexamethylenetetramine, glass fiber A (CS3E479, manufactured by Nittobo Co., Ltd., average particle size: 11 μm, average major axis) : 3 mm, average aspect ratio: 270) 1.5% by mass, Wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm) 55.0% by mass, calcined clay (Imelice) 17.5% by mass, Pole Star 501, average particle diameter: 0.6 μm), 1.0% by mass of magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.), and 2.0% by mass of other components such as a lubricant. %, Each is dry-mixed, melted and kneaded with a heating roll at 90 ° C., crushed and cooled to a granular thermosetting resin It was obtained Narubutsu (P2).
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P2) was 15 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 2 ppm / ° C.

Example 3
A metal resin composite 3 was produced in the same manner as in Example 1 except that the following thermosetting resin composition (P3) was used instead of the thermosetting resin composition (P1). This metal resin composite 3 was used as a test piece 3 and evaluated in the same manner as in Example 1.
20.0% by mass of novolak-type phenolic resin (PR-51305, manufactured by Sumitomo Bakelite Co., Ltd.), 3.0% by mass of hexamethylenetetramine, glass fiber A (CS3E479, manufactured by Nittobo Co., Ltd., average particle size: 11 μm, average major axis) : 3 mm, average aspect ratio: 270) 4.5% by mass, wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm) 55.0% by mass, calcined clay (Imelice) 14.5% by mass, Pole Star 501, average particle size: 0.6 μm), 1.0% by mass of magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.), and 2.0% by mass of other components such as a lubricant %, Each is dry-mixed, melted and kneaded with a heating roll at 90 ° C., crushed and cooled to a granular thermosetting resin It was obtained Narubutsu (P3).
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P3) was 16 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 1 ppm / ° C.

Example 4
A metal resin composite 4 was produced in the same manner as in Example 1 except that the following thermosetting resin composition (P4) was used instead of the thermosetting resin composition (P1). This metal resin composite 4 was used as a test piece 4 and evaluated in the same manner as in Example 1.
Resol type phenol resin (Sumitomo Bakelite Co., Ltd., PR-513723) 20.0% by mass, glass fiber A (CS3E479, Nittobo Co., Ltd., average particle size: 11 μm, average major axis: 3 mm, average aspect ratio: 270) 20.0% by mass, wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm), 40.0% by mass, calcined clay (Imeris, Polestar 501, average particle size) : 0.6 μm) is 15.0% by mass, magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.) is 2.0% by mass, and other components such as a lubricant are 3.0% by mass, each of which is dry-mixed. The mixture was melt-kneaded with a heating roll at 0 ° C., cooled into a sheet, and pulverized to obtain a granular thermosetting resin composition (P4).
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P4) was 13 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 4 ppm / ° C.

(Example 5)
A metal resin composite 5 was produced in the same manner as in Example 1 except that the following thermosetting resin composition (P5) was used instead of the thermosetting resin composition (P1). The metal resin composite 5 was used as a test piece 5 and the same evaluation as in Example 1 was performed.
Resol type phenol resin (Sumitomo Bakelite Co., Ltd., PR-513723) 20.0% by mass, glass fiber A (CS3E479, Nittobo Co., Ltd., average particle size: 11 μm, average major axis: 3 mm, average aspect ratio: 270) 10.0% by mass, wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm), 40.0% by mass, calcined clay (manufactured by Imeris, Polestar 501, average particle size) : 0.6 μm) is 25.0% by mass, magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.) is 2.0% by mass, and other components such as a lubricant are 3.0% by mass, each of which is dry-mixed. The mixture was melt-kneaded with a heating roll at 0 ° C., cooled into a sheet, and pulverized to obtain a granular thermosetting resin composition (P5).
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P5) was 12 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 5 ppm / ° C.

(Example 6)
A metal resin composite 6 was prepared in the same manner as in Example 1 except that the following stainless steel sheet 2 was used instead of the stainless steel sheet 1. This metal resin composite 6 was used as a test piece 6 and evaluated in the same manner as in Example 1.
An aqueous solution of sulfuric acid (50 mass%), cupric sulfate pentahydrate (3 mass%), potassium chloride (3 mass%), and thiosalicylic acid (0.0001 mass%) was prepared. And in the obtained aqueous solution (30 degreeC), the stainless steel sheet A was immersed and rock | fluctuated, and 30 micrometers (calculated from the weight which stainless steel decreased) was dissolved in the depth direction. Subsequently, it washed with water and dried and the stainless steel sheet 2 was obtained.
The characteristics of the stainless steel sheet 2 were as follows.
Ra: 2.8 μm
Rz: 28.0 μm
Specific surface area: 280
Glossiness: 8
Roughening layer thickness: 30 μm
Average depth of recess: 28 μm
Average cross-sectional width of the opening: 5 μm
Linear expansion coefficient α _M : 17 ppm / ° C.
In addition, the cross section of the concave portion has a shape having a cross sectional width larger than the cross sectional width of the opening portion at least at a part between the opening portion and the bottom portion of the concave portion.

(Example 7)
A metal resin composite 7 was prepared in the same manner as in Example 1 except that the following stainless steel sheet 3 was used instead of the stainless steel sheet 1. The metal resin composite 7 was used as a test piece 7, and the same evaluation as in Example 1 was performed.
An aqueous solution of sulfuric acid (50 mass%), cupric sulfate pentahydrate (3 mass%), potassium chloride (3 mass%), and thiosalicylic acid (0.0001 mass%) was prepared. And in the obtained aqueous solution (30 degreeC), the stainless steel sheet A was immersed and rock | fluctuated, and was dissolved 4 micrometers (calculated from the weight which stainless steel decreased) in the depth direction. Subsequently, it washed with water and dried and the stainless steel sheet 3 was obtained.
The characteristics of the stainless steel sheet 3 were as follows.
Ra: 1.1 μm
Rz: 4.0 μm
Specific surface area: 165
Glossiness: 13
Roughening layer thickness: 4 μm
Average depth of recess: 4 μm
Average cross-sectional width of the opening: 3 μm
Linear expansion coefficient α _M : 17 ppm / ° C.
In addition, the cross section of the concave portion has a shape having a cross sectional width larger than the cross sectional width of the opening portion at least at a part between the opening portion and the bottom portion of the concave portion.

(Example 8)
A metal resin composite 8 was produced in the same manner as in Example 1 except that the following thermosetting resin composition (P6) was used instead of the thermosetting resin composition (P1). This metal resin composite 8 was used as a test piece 8, and the same evaluation as in Example 1 was performed.
20.0% by mass of novolak-type phenolic resin (PR-51305, manufactured by Sumitomo Bakelite Co., Ltd.), 3.0% by mass of hexamethylenetetramine, glass fiber A (CS3E479, manufactured by Nittobo Co., Ltd., average particle size: 11 μm, average major axis) : 3 mm, average aspect ratio: 270) 3.0% by mass, Wollastonite B (manufactured by NYCO Minerals, NYAD5000, average particle size: 3 μm, average major axis: 9 μm, average aspect ratio: 3) 55.0 mass %, 16.0% by mass of calcined clay (Imeris, Polestar 501, average particle size: 0.6 μm), 1.0% by mass of magnesium oxide (manufactured by Kamishima Chemical Co., Ltd.), other lubricants, etc. 2.0% by mass of the components were each dry-mixed, melted and kneaded with a heating roll at 90 ° C., cooled into a sheet, and pulverized The thermosetting resin composition of granulated (P6) was obtained.
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P6) was 14 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 3 ppm / ° C.

Example 9
A metal resin composite 9 was prepared in the same manner as in Example 1 except that the following thermosetting resin composition (P7) was used instead of the thermosetting resin composition (P1). This metal resin composite 9 was used as a test piece 9, and the same evaluation as in Example 1 was performed.
20.0% by mass of novolak-type phenolic resin (PR-51305, manufactured by Sumitomo Bakelite Co., Ltd.), 3.0% by mass of hexamethylenetetramine, glass fiber A (CS3E479, manufactured by Nittobo Co., Ltd., average particle size: 11 μm, average major axis) : 3 mm, average aspect ratio: 270) 3.0% by mass, wollastonite A (manufactured by NYCO Minerals, NYAD325, average particle size: 10 μm, average major axis: 50 μm) 71.0% by mass, magnesium oxide (Kanjima) (Chemical Industry Co., Ltd.) 1.0% by mass and other components such as a lubricant 2.0% by mass, respectively, were dry-mixed, melted and kneaded with a heating roll at 90 ° C., and cooled into a sheet. The product was pulverized to obtain a granular thermosetting resin composition (P7).
The average value of the linear expansion coefficient α _R of the resin member sheet having a thickness of 3 mm made of the thermosetting resin composition (P7) was 15 ppm / ° C. Therefore, the absolute value of the difference in linear expansion coefficient (α _R −α _M ) was 2 ppm / ° C.

(Comparative Example 1)
Instead of the stainless steel sheet 1, a metal resin composite 10 was produced in the same manner as in the eighth example except that the stainless steel sheet A that was not subjected to the surface treatment used in the first example was used. This metal resin composite 10 was used as a test piece 10 and evaluated in the same manner as in Example 1.
The characteristics of the stainless steel sheet A were as follows.
Ra: 0.5 μm
Rz: 0.7 μm
Specific surface area: 50
Glossiness: 260
Linear expansion coefficient α _M : 17 ppm / ° C.
Further, the cross section of the concave portion was not in a shape having a cross sectional width larger than the cross sectional width of the opening portion in at least a part between the opening portion and the bottom portion of the concave portion.

(Comparative Example 2)
A resin member 11 was produced in the same manner as in Example 8 except that the stainless steel sheet 1 was not used. This resin member 11 was used as a test piece 11 and the same evaluation as in Example 1 was performed.

Table 1 and Table 2 show the above blending ratios and evaluation results. In addition, even if it performs each above-mentioned evaluation regarding a resin member, a metal member, and a metal resin composite using the test piece cut out from the brake piston produced in Example 1, the same evaluation result as the test piece 1 is obtained. It is understood. Moreover, even if the shape of the test piece cut out from the brake piston is different from the shape of the test piece 1, it is understood that the same evaluation result can be obtained by converting as necessary. The same applies to Examples 2 to 9 and Comparative Examples 1 and 2.

The metal resin composites 1 to 9 obtained in Examples 1 to 9 were excellent in bending strength retention. Even if the brake piston manufactured under the same conditions as those of the metal resin composites 1 to 9 is stored for 100 hours while the metal member is kept in contact with the hot plate at 350 ° C., both the piston main body and the metal member No peeling was observed during the period.
Further, since the brake pistons of Examples 1 to 9 were made of a metal resin composite, they were lighter than brake pistons made of only the same kind of metal.
From the above, the brake pistons of Examples 1 to 9 were excellent in performance balance between light weight and reliability.
On the other hand, the metal resin composite 10 obtained in Comparative Example 1 and the resin member 11 obtained in Comparative Example 2 were both inferior in bending strength retention. When the brake piston produced under the same conditions as the metal resin composite 10 was stored for 100 hours while the metal member was kept in contact with the hot plate at 350 ° C., peeling was observed between the piston body and the metal member. Further, when the brake piston manufactured under the same condition as the resin member 11 was stored for 100 hours while being in contact with a hot plate at 350 ° C., blisters were generated on the surface. That is, the brake pistons of Comparative Examples 1 and 2 were inferior in the performance balance between lightness and reliability.

This application claims priority based on Japanese Patent Application No. 2014-084268 filed on April 16, 2014, the entire disclosure of which is incorporated herein.

Claims (17)

1. A brake piston used for a disc brake,
   A piston body having an opening and made of a resin member;
   A metal member provided so as to cover a side end surface of the opening of the piston main body,
   The side end surface of the opening in the piston main body and the metal member are joined,
   The metal member has a roughened layer composed of fine irregularities on at least a joint surface to be joined to the piston main body part,
   The brake piston in which the side end face of the opening in the piston main body and the metal member are joined by the presence of a part of the resin member inside the concave portion constituting the irregularity of the roughened layer.
2. The brake piston according to claim 1,
   The brake piston has a cross-sectional shape in which the cross-sectional shape of the concave portion has a cross-sectional width larger than the cross-sectional width of the opening portion in at least a part between the opening portion and the bottom portion of the concave portion.
3. The brake piston according to claim 1 or 2,
   The brake piston, wherein the roughened layer has a thickness in the range of 3 µm to 40 µm.
4. The brake piston according to any one of claims 1 to 3,
   A brake piston having a gloss of 0.1 to 30 at a measurement angle of 60 ° measured in accordance with ASTM-D523 of the joint surface of the metal member joined to the piston main body.
5. The brake piston according to any one of claims 1 to 4,
   A brake piston, wherein a ratio of an actual surface area according to a nitrogen adsorption BET method to an apparent surface area of the joint surface joined to the piston main body portion of the metal member is 100 or more and 400 or less.
6. The brake piston according to any one of claims 1 to 5,
   The brake member is a brake piston made of a thermosetting resin composition including a thermosetting resin and a filler.
7. The brake piston according to claim 6,
   A brake piston in which a part of the filler is present inside a recess that constitutes the unevenness of the roughened layer.
8. The brake piston according to claim 7,
   The filler present inside the recess is a kind selected from the group consisting of wollastonite, kaolin clay, talc, calcium carbonate, zinc oxide, calcium silicate hydrate, aluminum borate whisker, and potassium titanate fiber Or two or more brake pistons.
9. The brake piston according to any one of claims 6 to 8,
   The brake piston, wherein the thermosetting resin is a phenol resin.
10. The brake piston according to any one of claims 1 to 9,
    A brake piston in which the side end face of the opening in the piston main body and the metal member are joined without an adhesive.
11. The brake piston according to any one of claims 1 to 10,
    The metal member is a brake piston formed of one or more metal materials selected from the group consisting of iron, stainless steel, aluminum, aluminum alloy, magnesium, magnesium alloy, copper and copper alloy.
12. A disc brake comprising the brake piston according to any one of claims 1 to 11.
13. A manufacturing method for manufacturing the brake piston according to any one of claims 1 to 11,
    Preparing a metal member and a mold;
    Disposing the metal member in a molding space of the mold; and
    Filling the molding space with a thermosetting resin composition containing a thermosetting resin;
    The resin member made of the thermosetting resin composition and the metal member by curing the thermosetting resin composition in a state where at least a part of the thermosetting resin composition is in contact with the metal member. To obtain a brake piston,
    A method for manufacturing a brake piston.
14. The method of manufacturing a brake piston according to claim 13,
    In the step of preparing the metal member and the mold,
    A method for manufacturing a brake piston, comprising preparing the metal member having a roughened surface of at least a portion to be joined to the resin member of the surface of the metal member.
15. In the manufacturing method of the brake piston according to claim 13 or 14,
    In the filling step, the brake piston is manufactured by filling the molding space with the thermosetting resin composition while pressing the metal member against the molding surface of the mold by the flow pressure of the thermosetting resin composition. Method.
16. A thermosetting resin composition used for forming the resin member constituting the brake piston according to any one of claims 1 to 11,
    A thermosetting resin composition comprising a thermosetting resin and a filler.
17. In the thermosetting resin composition according to claim 16,
    The thermosetting resin composition, wherein the thermosetting resin is a phenol resin.

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