Brake pad, metal-containing composition, brake, and method for producing brake pad

Abstract

This brake pad has, on a sliding surface, a metal-containing layer containing 70% by mass or more of a resin and at least one compound selected from the group consisting of a titanium compound, a magnesium compound and a lithium compound.

Description

Brake pad, metal-containing composition, brake, and method for manufacturing brake pad

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to brake pads, metal-containing compositions, brakes, and methods of making brake pads.

[0002] Disc brakes used in automobiles, motorcycles, etc. are components in which a disc rotor is sandwiched between two disc brake pads, and braking is performed by friction between them.

[0003] Disc brake pads typically used in automobiles, motorcycles, and other vehicles are manufactured by mixing organic fibers, inorganic fibers, metal fibers, friction modifiers, and phenolic resins, combining them with a metal plate called a backplate in a press, hardening them into a predetermined shape, heat treating them, and then processing them into the desired shape (see, for example, Patent Document 1). After the heat treatment, the pads may be scorched, a process in which the surface is baked at high temperatures, to stabilize the coefficient of friction. After these processes, a mixture of resin, abrasives, and the like may be applied to the friction surface. This is done to address the problem of insufficient contact between the disc brake pad and the disc rotor at the start of braking, resulting in a lower-than-normal coefficient of friction.

[0004] Patent No. 5797073

[0005] The braking force of a disc brake is generated by the friction between the disc rotor and brake lining, but initially (for example, when a new brake is installed), the two components do not bond well together. Normally, the initial state of the disc rotor surface is pure iron, but as the disc rotor is used, a transfer film from the friction material forms on the surface, stabilizing the coefficient of friction and wear. Therefore, it takes several hundred braking cycles to achieve the originally designed braking friction.

[0006] In recent years, as electric vehicles have become more common and battery mass has increased, brakes have also become larger to ensure braking force in emergencies. However, regenerative braking reduces the brake load during normal operation. This has created a problem in that it takes time for the braking force to reach the designed braking force. Meanwhile, as autonomous driving of automobiles progresses, if a constant braking force cannot be obtained at all times, the vehicle will not decelerate as designed, which is an even greater problem.

[0007] The present disclosure has been made in consideration of the above-described conventional circumstances, and aims to provide a brake pad having excellent stability in the initial friction coefficient, a manufacturing method for a brake pad capable of producing the brake pad, a metal-containing composition, and a brake equipped with the brake pad.

[0008] Specific means for achieving the above object are as follows. <1> A brake pad having, on its sliding surface, a metal-containing layer containing 70 mass % or more of a resin and at least one compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds. <2> The brake pad according to <1>, wherein the metal-containing layer contains a resin that supports the at least one compound on the sliding surface, and does not contain particles having an average particle diameter of more than 50 μm or a fibrous substrate. <3> The brake pad according to <1> or <2>, wherein the metal-containing layer has a thickness of 1 μm to 1000 μm. <4> A metal-containing composition that includes at least one compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, and at least one material selected from a resin and a resin precursor, and is used to form a metal-containing layer containing the at least one compound and resin on a substrate of a brake pad. <5> The metal-containing composition according to <4>, wherein the at least one material is thermosetting or photocurable. <6> The metal-containing composition according to <4> or <5>, wherein the at least one compound includes the titanium compound, and the titanium compound is at least one selected from the group consisting of titanium oxide, lithium titanate, potassium titanate, magnesium titanate, lithium potassium titanate, and titanocene. <7> The metal-containing composition according to any one of <4> to <6>, wherein a total content of the at least one compound is 1 mass % to 80 mass %. <8> A brake comprising a brake rotor and the brake pad according to any one of <1> to <3>. <9> A method for manufacturing a brake pad, comprising: adhering to a substrate of the brake pad a powder containing at least one compound selected from the group consisting of a titanium compound, a magnesium compound, and a lithium compound; or applying to a substrate of the brake pad a liquid composition in which the powder is dissolved or dispersed in a liquid.

[0009] According to one embodiment of the present disclosure, it is possible to provide a brake pad having excellent stability of the initial friction coefficient, a brake pad manufacturing method and metal-containing composition capable of producing the brake pad, and a brake including the brake pad.

[0010] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit the present disclosure.

[0011] In the present disclosure, numerical ranges indicated using "to" include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in the present disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another staged numerical range. Furthermore, in numerical ranges described in the present disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple corresponding substances. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, particles corresponding to each component may include multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified. In the present disclosure, the term "layer" includes cases where the layer is formed over the entire area when the area where the layer is present is observed, as well as cases where the layer is formed only in a part of the area. The average particle size of the particles refers to the 50% (median) diameter (D50) determined from the volume distribution of particle size distribution measured with a laser diffraction / scattering particle size distribution analyzer. The average particle size can be measured, for example, with an LA-920 (manufactured by Horiba, Ltd.).

[0012] [Brake Pad] The brake pad of the present disclosure has, on its sliding surface, a metal-containing layer containing 70 mass % or more of at least one compound selected from the group consisting of a titanium compound, a magnesium compound, and a lithium compound (hereinafter also referred to as a "specific metal compound") and a resin.

[0013] The brake pad of the present disclosure exhibits excellent stability of the coefficient of friction during the initial break-in process between the brake pad and the brake rotor, thereby shortening the break-in process. The reason for this is presumed to be as follows: specific metal compounds penetrate the surface of the brake rotor and form a dense metal-containing layer on the sliding surface, thereby shortening the break-in process and achieving a stable coefficient of friction.

[0014] Furthermore, with the brake pads of the present disclosure, for example, the coefficient of friction is stabilized from around 100°C at the start of use to around 300°C, particularly around 100°C, improving brake pad wear. As a result, wear debris can be reduced, reducing the generation of substances harmful to the environment and humans. Furthermore, the use of environmental pollutants can also be reduced.

[0015] The brake pads of the present disclosure can reduce the number of braking cycles required to achieve a predetermined braking force, thereby shortening the time required to achieve stable braking force, even in vehicles with a low braking load, such as electric vehicles.

[0016] The brake pad of the present disclosure may be, for example, a brake pad used in an automobile, a motorcycle, etc. The brake pad may be a pad for a disc brake.

[0017] The brake pad of the present disclosure may have a metal-containing layer on the sliding surface, and the metal-containing layer may be formed on at least a portion of the sliding surface, or the metal-containing layer may be formed on a portion of the sliding surface, or the metal-containing layer may be formed on the entire sliding surface. The area of ​​the sliding surface on which the metal-containing layer is formed may be 50% to 100%, or may be 70% to 100%, of the total area of ​​the sliding surface.

[0018] The specific metal compound includes a compound containing at least one cation selected from the group consisting of titanium cations, magnesium cations, and lithium cations, such as hydroxides, carbonates, sulfates, halides, oxides, complex acid salts such as titanium complex acid salts, and organometallic compounds such as organometallic compounds containing titanium.

[0019] Examples of hydroxides include magnesium hydroxide and lithium hydroxide. Examples of carbonates include magnesium carbonate and lithium carbonate. Examples of sulfates include titanium sulfate and magnesium sulfate. Examples of halides include titanium trichloride, titanium tetrachloride, magnesium chloride, magnesium bromide, lithium chloride, and lithium bromide. Examples of oxides include titanium oxide and magnesium oxide. Examples of titanium complex salts include M ｘ O (titanium oxide) ｙ The titanium complex salt is represented by the general formula: ｘ O is an oxide containing a cation represented by M, and x and y are integers. Examples of titanium composite salts include lithium titanate, magnesium titanate, lithium potassium titanate, titanocene, potassium titanate, and lithium potassium titanate. Examples of organometallic compounds containing titanium include titanocene and bis(η5-cyclopentadienyl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium.

[0020] The specific metal compound is preferably a titanium compound, and from the viewpoint of shortening the friction stabilization time, the titanium compound is preferably at least one selected from the group consisting of titanium oxide, lithium titanate, potassium titanate, magnesium titanate, lithium potassium titanate, and titanocene.

[0021] The specific metal compound contained in the metal-containing layer may be in the form of particles. In this case, the particle diameter of the specific metal compound is preferably ½ or less of the film thickness described below, from the viewpoint of forming a highly uniform metal-containing layer. From the viewpoint of safety, the particle diameter of the specific metal compound is preferably 0.3 μm or more, more preferably 0.3 μm to 50 μm, and even more preferably 0.3 μm to 25 μm.

[0022] The amount of the specific metal compound contained in the metal-containing layer, i.e., the amount of the specific metal compound carried per unit area of ​​the sliding surface of the brake pad, also depends on the density of the specific metal compound. However, from the viewpoint of preferably exhibiting the effects of the invention and reducing the amount of the specific metal compound used, it is preferable to set the amount to 0.01 mg / cm. ２ ~25 mg / cm ２ and preferably 0.2 mg / cm ２ ~12.5mg / cm ２ It is more preferable that:

[0023] Methods for forming a metal-containing layer on the sliding surface of a brake pad include a method of adhering a powder of a specific metal compound or a powder containing a specific metal compound to the substrate of the brake pad, a method of applying a liquid composition in which the powder is dissolved or dispersed in a liquid to the substrate of the brake pad, and a method of forming a metal-containing layer all at once or in stages on the sliding surface during the manufacturing process of the brake pad. Methods for applying the metal-containing layer to the substrate of the brake pad include a method of applying the liquid composition by a dispenser, spray, cast coating, spin coating, etc.

[0024] From the viewpoint of suppressing the powder falling off, the metal-containing layer contains a resin that supports a specific metal compound on the sliding surface. The resin that supports the specific metal compound on the sliding surface is preferably one that can form a resin coating film on the sliding surface, and may be, for example, one formed from a resin precursor.

[0025] Examples of methods for forming a metal-containing layer containing a resin that supports a specific metal compound on the sliding surface include a method in which a powder of the specific metal compound or a powder containing the specific metal compound is dissolved or dispersed in a liquid, and the liquid composition in which the above-mentioned resin or a resin precursor thereof is dissolved or dispersed in a liquid is applied to the substrate of the brake pad.

[0026] The resin or its resin precursor is preferably dissolved in a liquid that dissolves or disperses the powder. When a liquid composition is used, it is preferable to heat the liquid composition after application in order to evaporate the liquid. The heating temperature depends on the boiling point of the liquid in the liquid composition, but is preferably a temperature between the boiling point minus 30°C and the boiling point plus 130°C.

[0027] When a liquid composition containing the resin or its resin precursor is used, the resin coating film formed on the sliding surface may be heated as needed to form a metal-containing layer containing a resin that supports a specific metal compound on the sliding surface. At this time, heating may be performed at a temperature equal to or higher than the melting point of the resin as needed.

[0028] The resin or resin precursor thereof may be a thermoplastic material, or may be a thermosetting or photocurable material. For example, the metal-containing layer may be formed by heating the resin coating film formed on the sliding surface or by irradiating the resin coating film with light to cure the resin coating film.

[0029] The above-mentioned resin or its resin precursor, which is a thermosetting or photocurable material, may be dissolved or dispersed in a liquid that dissolves or disperses powder. The above-mentioned resin and its resin precursor may be used in combination from the viewpoint of adjusting the melting point of the material and the viscosity of the liquid composition. When the resin precursor is liquid, the resin precursor may be a liquid that dissolves or disperses powder, and may not contain any other liquid.

[0030] When the above-mentioned resin or its resin precursor, which is a thermosetting material, is used, the resin coating film needs to be heated to a temperature higher than the curing initiation temperature, and when a polymerization initiation catalyst is used, the resin coating film needs to be heated to a temperature higher than the polymerization initiation temperature.When the above-mentioned resin or its resin precursor, which is a photocurable material, is used, it is preferable to use a photopolymerization initiator, and a wavelength and exposure amount suitable for the photopolymerization initiator are required.

[0031] As a method for forming the specific metal-containing layer, a method in which a powder of a specific metal compound or a powder containing a specific metal compound is mixed with the above-mentioned resin or a resin precursor thereof and then pressure-heat-molded onto the sliding surface side of the brake pad substrate can be mentioned. Alternatively, when manufacturing the brake pad substrate, a mold can be filled with the friction material composition and the backing metal in two layers, and then pressure-heat-molded.

[0032] Examples of the resins include epoxy resins, phenolic resins, urethane resins, fluororesins, polyester resins, amide resins, amide-imide resins, imide resins, melamine resins, urethane resins, phenoxy resins, silicone resins, silicic acid resins, acrylic resins, and olefin resins. Examples of the resin precursors include precursors of these resins. The resins or resin precursors may be used independently, either singly or in combination. From the viewpoint of applicability and availability, the resins and resin precursors preferably include at least one selected from the group consisting of epoxy resins, phenolic resins, silicic acid resins, acrylic resins, and precursors thereof, more preferably at least one of phenolic resins and acrylic resins, even more preferably phenolic resins, and particularly preferably thermosetting phenolic resins.

[0033] The total content of the specific metal compounds may be 10% by mass to 80% by mass, or may be 20% by mass to 70% by mass, based on the total amount of the metal-containing layer.

[0034] The content of the resin may be 20% by mass to 90% by mass, or 30% by mass to 80% by mass, based on the total amount of the metal-containing layer.

[0035] The total content of the specific metal compound and resin is 70% by mass or more, or may be 70% by mass to 100% by mass, or may be 90% by mass to 100% by mass, based on the total amount of the metal-containing layer.

[0036] The metal-containing layer preferably contains a resin that supports at least one compound on the sliding surface, and does not contain particles having an average particle size of more than 50 μm or a fibrous base material. When the brake pad includes a friction material containing particles having an average particle size of more than 50 μm and a fibrous base material, the metal-containing layer is preferably a layer separate from the friction material, and is preferably formed on at least a portion of the friction material.

[0037] The thickness of the metal-containing layer may be 1 μm to 1000 μm, or 10 μm to 500 μm. By making the thickness of the metal-containing layer 500 μm or less, the friction stabilization time can be shortened and the resin can be prevented from turning into tar when heated, which can cause a decrease in the friction coefficient, known as fade.

[0038] [Metal-Containing Composition] The metal-containing composition of the present disclosure contains at least one compound (specific metal compound) selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, and at least one material selected from a resin and a resin precursor, and is a composition used for forming a metal-containing layer containing the at least one compound and a resin on a substrate of a brake pad.

[0039] The metal-containing composition of the present disclosure is used, for example, to form a metal-containing layer on the sliding surface of a substrate of a brake pad formed using a friction material and a backing metal. The friction material may be, for example, a member formed by molding a friction material composition containing inorganic fibers, organic fibers, metal fibers, an abrasive, a friction modifier, and a phenolic resin. The brake pad of the present disclosure can be obtained by forming a metal-containing layer using the metal-containing composition of the present disclosure.

[0040] Preferred forms of the specific metal compound and at least one material of the resin and resin precursor contained in the metal-containing composition of the present disclosure are as described above in the section on brake pads.

[0041] The metal-containing composition of the present disclosure may be a liquid material (for example, the liquid composition described above) or a powder material. A liquid material is preferred from the viewpoint that a highly uniform metal-containing layer can be formed and various application methods can be adopted. Methods for applying the powder material to the brake pad substrate include powder coating using a tribo gun, corona gun, etc. Alternatively, the metal-containing layer can be formed by pressurized heat molding during production. Methods for applying the liquid material to the brake pad substrate include spraying, roll coating, etc.

[0042] The ratio of the total amount of resin and resin precursor to the total amount of specific metal compound (resin and resin precursor / specific metal compound) may be 0.2 to 10, 0.5 to 8, or 1 to 5 in terms of mass ratio, from the viewpoint of suppressing powder falling and fading.

[0043] The metal-containing composition of the present disclosure contains, as essential components, a specific metal compound and at least one material selected from the group consisting of a resin and a resin precursor, and may, if necessary, contain a liquid that dissolves or disperses the specific metal compound (e.g., a powdered specific metal compound), a polymerization initiator, other additives, and the like.

[0044] From the viewpoint of forming a metal-containing layer having excellent thickness uniformity, the metal-containing composition of the present disclosure preferably contains a liquid that dissolves or disperses specific metal compounds. The total content of the specific metal compounds may be appropriately adjusted depending on whether the specific metal compounds are dissolved or dispersed in the liquid.

[0045] In the metal-containing composition of the present disclosure, the total content of the specific metal compounds may be 1% by mass to 80% by mass, or 5% by mass to 70% by mass, relative to the total amount of the metal-containing composition, from the viewpoints of enabling spray coating and facilitating adjustment of the film thickness.

[0046] In the metal-containing composition of the present disclosure, the total content of the resin and the resin precursor may be 3% by mass to 99% by mass, or 10% by mass to 95% by mass, based on the total amount of the metal-containing composition.

[0047] When a liquid that dissolves or disperses a specific metal compound is used in the metal-containing composition of the present disclosure, the total content of the specific metal compound, resin, and resin precursor may be 5% by mass to 50% by mass, or 10% by mass to 30% by mass, relative to the total amount of the metal-containing composition.

[0048] The liquid for dissolving or dispersing the specific metal compound is preferably a liquid having a boiling point of −30° C. to 220° C., from the viewpoint of volatilizing at room temperature or within the usable temperature range of a general hot air dryer, and more preferably a liquid having a boiling point of −30° C. to 130° C., from the viewpoint of drying efficiency. A boiling point of −30° C. or higher tends to facilitate film thickness adjustment by adjusting the volatilization rate of the liquid, and a boiling point of 130° C. or lower tends to enable a reduction in the amount of heat required to distill off the liquid.

[0049] Examples of liquids having a boiling point of −30° C. to 220° C. include water, diethyl ether, acetone, methyl ethyl ketone, ethyl acetate, ethanol, toluene, xylene, N-methylpyrrolidone, dimethylacetamide, and 1-methoxy-2-propanol. Examples of liquids having a boiling point of −30° C. to 130° C. include diethyl ether, acetone, methyl ethyl ketone, ethyl acetate, ethanol, toluene, and 1-methoxy-2-propanol.

[0050] When a liquid that dissolves or disperses a specific metal compound is used in the metal-containing composition of the present disclosure, the content of the liquid may be 30% by mass to 95% by mass, or may be 50% by mass to 90% by mass, relative to the total amount of the metal-containing composition.

[0051] When at least one of the resin and the resin precursor is a thermosetting or photocurable material, the metal-containing composition of the present disclosure may contain a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator.

[0052] As the polymerization initiator, commercially available radical or cationic polymerization initiators can be used, and organic peracids, azo-based radical polymerization initiators, etc. may also be used. As a radical photopolymerization initiator, bis(η5-cyclopentadienyl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium (e.g., Irgacure 784 manufactured by IGM Resins) may also be used. This material can serve as both a photopolymerization initiator and a titanium compound.

[0053] The metal-containing composition of the present disclosure may contain other additives, such as crosslinkers, sensitizers, friction modifiers, viscosity modifiers, surfactants, leveling agents, metal deactivators, colorants, and fragrances.

[0054] An example of the crosslinking agent is hexamethylenetetramine. When a crosslinking agent is used, it is preferable to further use a phenolic resin, and the amount of the crosslinking agent used is preferably 1% by mass to 12% by mass, more preferably 3% by mass to 8% by mass, based on the phenolic resin contained in the metal-containing composition.

[0055] [Brake] The brake of the present disclosure includes a brake rotor and the brake pad of the present disclosure described above. The brake may include a disc rotor and a disc brake pad, and may be a brake used in an automobile, a motorcycle, or the like.

[0056] The brake rotor may be an iron or iron alloy rotor, preferably a cast iron rotor or a stainless steel rotor.

[0057] The brake pad may be, for example, a component formed using a friction material formed by molding a friction material composition and a backing metal. A primer layer for surface modification to enhance the adhesive effect of the backing metal to the friction material, and an adhesive layer for bonding the backing metal and the friction material may be further interposed between the backing metal and the friction material.

[0058] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples in any way.

[0059] (Preparation of anatase-type titanium oxide coating solution) 2 g of anatase-type titanium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dispersed in a solution of 4 g of phenolic resin and 20 g of methyl ethyl ketone to obtain an anatase-type titanium oxide coating solution. Phenolic resin 1, which was a straight phenolic resin (manufactured by Cashew Co., Ltd., hexamethylenetetramine-free) to which 6% by mass of hexamethylenetetramine had been added, was used as the phenolic resin. Because titanium oxide settles over time, the solution was thoroughly stirred immediately before use to disperse the titanium oxide.

[0060] Example 1 (Preparation of Pad Containing Anatase-Type Titanium Oxide on the Sliding Surface) The anatase-type titanium oxide coating solution prepared above was sprayed evenly onto the surface of a phenolic resin pad 2 of Comparative Example 2 described below, yielding a pad with a coating layer having a calculated thickness of approximately 200 μm. The disc brake pad was then heated in a constant temperature oven in stages from 125° C. to 200° C. to harden the phenolic resin, yielding a test pad with a titanium oxide layer.

[0061] Comparative Example 1 (Preparation of Phenolic Resin Pad 1) 20 g of phenolic resin 1 was filled into a mold, and the temperature was increased stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0062] Comparative Example 2 (Preparation of Phenolic Resin Pad 2) 7 g of barium sulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 2.5 g of aramid fiber (manufactured by Teijin DuPont), 0.5 g of α-alumina (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 9 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0063] (Friction Evaluation) The test pads of each Example or Comparative Example were cut into test pieces (10 mm x 10 mm x approximately 15 mm, two pieces), and the time and temperature until the friction coefficient stabilized were evaluated using a friction measuring machine (FRICTRON EFM-3-F-ADX manufactured by A&D Co., Ltd.) with a cast iron rotor. The test conditions were 3000 rpm (revolutions per minute) and 370 N. The internal temperature was continuously measured approximately 5 mm from the pad surface using a thermocouple.

[0064] The friction coefficient increased initially, then gradually decreased and stabilized. To evaluate the friction coefficient, the friction coefficient obtained from 30 seconds after the start was approximated by a quintic equation using numerical processing (Microsoft Excel). The differential value of this approximation was calculated, and the time and temperature at which the change was -0.001 or more was considered to be the time when friction stabilized. The results are shown in Table 1.

[0065]

[0066] As shown in Example 1 of Table 1, the coefficient of friction was stabilized by applying an anatase titanium oxide coating solution to the surface of the pad. This is presumably because a specific metal compound penetrates the rotor surface and forms a dense surface film on the sliding surface of the rotor, thereby stabilizing the initial coefficient of friction.

[0067] In order to identify a specific metal compound that exhibits the same effect as in Example 1, a pad simulating the surface layer was prepared and subjected to a friction test.

[0068] Example 2 (Preparation of Anatase-Type Titanium Oxide-Containing Pad) 2 g of anatase-type titanium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0069] Example 3 (Preparation of titanocene-containing pad) 2 g of titanocene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0070] [Example 4] (Preparation of Potassium Titanate-Containing Pad) 2 g of potassium titanate (manufactured by Alfa Aesar) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0071] [Example 5] (Preparation of Lithium Carbonate-Containing Pad) 2 g of lithium carbonate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed, filled into a mold, and heated stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0072] [Example 6] (Preparation of magnesium oxide-containing pad) 2 g of heavy magnesium oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0073] [Example 7] (Preparation of magnesium sulfate-containing pad) 2 g of magnesium sulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0074] [Example 8] (Preparation of magnesium hydroxide-containing pad) 2 g of magnesium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed and filled into a mold. The temperature was then raised stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0075] Example 9 (Preparation of Lithium Sulfate-Containing Pad) 2 g of lithium sulfate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 18 g of phenolic resin 1 were uniformly mixed, filled into a mold, and heated stepwise from 125°C to 200°C under reduced pressure in the pressure range of 3 MPa to 6 MPa to obtain a test pad.

[0076] Friction evaluation was carried out using the test pads of Examples 2 to 9. The friction evaluation was carried out in the same manner as described above, and the results are shown in Table 2 together with those of Comparative Examples 1 and 2 described above.

[0077]

[0078] As shown in Examples 2 to 9 in Table 2, the inclusion of a specific metal compound shortened the time until friction stabilization and stabilized the friction coefficient at a lower temperature. As in Example 1, this is presumably because the specific metal compound penetrates the rotor surface and forms a dense surface film on the sliding surface of the rotor, thereby achieving stability in the initial friction coefficient.

[0079] The disclosure of Japanese Patent Application No. 2024-057351, filed on March 29, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A brake pad having a metal-containing layer on its sliding surface, the metal-containing layer containing 70% by mass or more of at least one compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, and a resin.

2. A brake pad according to claim 1, wherein the metal-containing layer contains a resin that supports the at least one compound on the sliding surface, and does not contain particles having an average particle size of more than 50 μm or a fibrous base material.

3. The brake pad according to claim 1, wherein the thickness of said metal-containing layer is 1 μm to 1000 μm.

4. A metal-containing composition comprising at least one compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, and at least one material selected from the group consisting of a resin and a resin precursor, and used to form a metal-containing layer containing the at least one compound and a resin on the substrate of a brake pad.

5. The metal-containing composition of claim 4, wherein said at least one material is heat-curable or photo-curable.

6. The metal-containing composition of claim 4, wherein the at least one compound comprises the titanium compound, and the titanium compound is at least one selected from the group consisting of titanium oxide, lithium titanate, potassium titanate, magnesium titanate, lithium potassium titanate, and titanocene.

7. The metal-containing composition according to any one of claims 4 to 6, wherein the total content of the at least one compound is 1% by mass to 80% by mass.

8. A brake comprising a brake rotor and a brake pad according to any one of claims 1 to 3.

9. A method for manufacturing a brake pad, comprising adhering a powder containing at least one compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds to a substrate of a brake pad, or applying a liquid composition in which the powder is dissolved or dispersed in a liquid to the substrate of the brake pad.

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