Resin composition, brake rotor, kit for brake rotor production, brake rotor manufacturing method, and brake

Abstract

This resin composition contains at least one metal compound selected from the group consisting of titanium compounds, magnesium compounds and lithium compounds, an epoxy compound, and water, and is used for coating a sliding surface of a brake rotor.

Description

Resin composition, brake rotor, kit for producing brake rotor, method for manufacturing brake rotor, and brake

[0001] The present disclosure relates to a resin composition, a brake rotor, a kit for producing a brake rotor, a method for manufacturing a brake rotor, and a brake.

[0002] A disc brake, which is a type of brake used in a moving body (vehicle) equipped with wheels such as an automobile, a motorcycle, or a railway vehicle, is basically composed of a brake rotor and a pair of brake pads arranged on both sides of the brake rotor. The brake rotor is a disc-shaped member that rotates with the wheel, and when the brake pad is pressed against the brake rotor, a frictional force is generated between the two members, decelerating or stopping the rotation of the wheel.

[0003] Since the material of the brake rotor generally contains iron, rust may occur on the surface (hereinafter also referred to as the sliding surface) that contacts the brake pad of the brake rotor. When rust occurs on the sliding surface of the brake rotor, the brake pad and the brake rotor may stick together, making it difficult for the brake rotor to rotate, or vibration called brake judder may occur due to the difference in rust thickness between the part where the brake rotor contacts the brake pad and other parts. Therefore, various rust prevention treatments are being considered for the sliding surface of the brake rotor.

[0004] For example, Patent Document 1 proposes performing a chemical conversion treatment called dacro-dip treatment on the sliding surface of the brake rotor. Patent Document 2 proposes performing a nitriding treatment on the sliding surface of the brake rotor. Patent Documents 3 and 4 propose applying a material containing a reducing compound to the sliding surface of the brake rotor.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-323073 Patent Document 2: Japanese Patent Application Laid-Open No. 2016-164439 Patent Document 3: Japanese Patent Application Laid-Open No. 2004-510924 Patent Document 4: Japanese Patent No. 5706197

[0006] The sliding surface of a brake rotor changes to a new surface due to friction with the brake pads during the use of disc brakes. Therefore, preventing rust on the sliding surface of the brake rotor is more important during the period from the manufacture of the disc brake to its installation and use in a vehicle than during the period when the disc brake is installed and used in a vehicle. Furthermore, the braking force of a disc brake obtained by the friction between the brake rotor and brake pads tends to have unstable friction characteristics in its initial state (e.g., when new). Therefore, there is a need for the development of surface treatment technology for brake rotors that provides excellent initial rust prevention and contributes to the stabilization of initial friction characteristics. In addition, there is a growing demand for reducing the cost required for surface treatment of brake rotors and ensuring the safety of the surface treatment process.

[0007] This disclosure is made in view of the above-mentioned conventional circumstances and aims to provide a resin composition that enables the low-cost and safe manufacture of a brake rotor with excellent initial rust prevention effect and stability of initial friction characteristics, a brake rotor manufacturing kit containing the resin composition, and a method for manufacturing a brake rotor using the resin composition. Furthermore, this disclosure aims to provide a brake rotor with excellent initial rust prevention effect and stability of initial friction characteristics, and a brake equipped therewith.

[0008] The specific means for achieving the above objectives are as follows: <1> A resin composition used for coating the sliding surface of a brake rotor, comprising at least one metal compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, an epoxy compound, and water. <2> The resin composition according to <1>, wherein the metal compound comprises a titanium compound. <3> The resin composition according to <2>, wherein the titanium compound comprises at least one selected from the group consisting of titanium oxide and titanium black. <4> The resin composition according to any one of <1> to <3>, wherein the epoxy compound is dissolved or dispersed in water. <5> The resin composition according to any one of <1> to <4>, wherein the epoxy compound comprises a bisphenol-type epoxy compound. <6> The resin composition according to any one of <1> to <5>, which hardens at a temperature of 150°C or lower. <7> The resin composition according to any one of <1> to <6>, further comprising a curing accelerator for the epoxy compound, wherein the curing accelerator is dissolved in water. <8> A resin composition according to any one of <1> to <7>, further comprising an imidazole compound and hexamethylenetetramine. <9> A brake rotor having a layer containing a cured product of the resin composition according to any one of <1> to <8> on its sliding surface. <10> The brake rotor according to <9>, wherein the thickness of the layer is 1 μm to 100 μm. <11> A brake rotor manufacturing kit comprising the resin composition according to any one of <1> to <8> and the body of the brake rotor. <12> A method for manufacturing a brake rotor, comprising applying the resin composition according to any one of <1> to <8> to the sliding surface of the body of the brake rotor, and curing the resin composition to form a layer containing a cured product of the resin composition on the sliding surface. <13> A brake comprising the brake rotor according to <9> and a brake pad.

[0009] This disclosure provides a resin composition that enables the low-cost and safe manufacture of a brake rotor with excellent initial rust prevention and stability of initial friction characteristics, a brake rotor manufacturing kit containing the resin composition, and a method for manufacturing a brake rotor using the resin composition. Furthermore, this disclosure provides a brake rotor with excellent initial rust prevention and stability of initial friction characteristics, and a brake equipped therewith.

[0010] The following describes in detail the forms for implementing this disclosure. However, this disclosure is not limited to the following embodiments. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit this disclosure.

[0011] In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced by the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance 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 types of substances present in the composition, unless otherwise specified. In this disclosure, each particle corresponding to each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for the mixture of the multiple types of particles present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where, when observing the region in which the layer exists, it is formed not only over the entire region but also over only a portion of the region.

[0012] [Resin Composition] The resin composition of this disclosure comprises at least one metal compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds (hereinafter also referred to as "specific metal compound"), an epoxy compound, and water, and is a resin composition used for coating the sliding surface of a brake rotor.

[0013] The resin compositions of this disclosure are used for coating the sliding surfaces of brake rotors. More specifically, the resin compositions of this disclosure are used to form a layer on the sliding surfaces of brake rotors that includes a cured product of the resin compositions of this disclosure.

[0014] As shown in the embodiments described later, the sliding surface of a brake rotor on which a layer containing the cured resin composition of the present disclosure is formed exhibits superior initial rust prevention and superior stability of initial friction characteristics compared to the sliding surface of a brake rotor on which a layer containing the cured resin composition of the present disclosure is not formed. Furthermore, the layer containing the cured resin composition of the present disclosure is formed by applying the resin composition to the sliding surface of the brake rotor and curing it by heating or the like. Therefore, rust prevention treatment can be performed in a simpler and less costly manner compared to plating, chemical conversion treatment, etc. Furthermore, the resin composition of the present disclosure contains water as a solvent. Therefore, the resin composition of the present disclosure has a lower risk of fire, health damage, etc. during work compared to resin compositions in which the solvent is an organic solvent. The components contained in the resin composition of the present disclosure will be described below.

[0015] (Specific Metal Compounds) The resin compositions of this disclosure include, as specific metal compounds, at least one metal compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds.

[0016] Examples of specific metal compounds include compounds containing at least one metal cation selected from the group consisting of titanium cations, magnesium cations, and lithium cations. For example, examples of specific metal compounds include hydroxides, carbonates, sulfates, halides, oxides, complex salts such as titanium complex salts, titanium black, and organometallic compounds such as titanium-containing organometallic compounds.

[0017] 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 trichlorotitanium, tetrachlorotitanium, magnesium chloride, magnesium bromide, lithium chloride and lithium bromide. Examples of oxides include titanium dioxide and magnesium oxide. Examples of titanium complex salts include M ｘ O (Titanium Oxide) ｙ It is a titanium complex salt represented by the general formula. In the general formula, M ｘ O is an oxide containing a cation represented by M, and x and y are integers. Examples of titanium complex 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-pyrrole-1-yl)-phenyl)titanium.

[0018] From the viewpoint of initial rust prevention effect and stability of initial friction characteristics, the resin composition preferably contains a titanium compound as a specific metal compound. From the viewpoint of shortening the time until the initial friction characteristics stabilize, the specific metal compound preferably contains at least one selected from the group consisting of titanium oxide, titanium black, lithium titanate, potassium titanate, magnesium titanate, lithium potassium titanate, and titanocene, and more preferably at least one selected from the group consisting of titanium oxide and titanium black. From the viewpoint of availability, titanium oxide is preferred, and from the viewpoint of painting it black, titanium black is preferred.

[0019] Certain metal compounds may be in particulate form. In this case, the average particle size 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, from the viewpoint of safety. In this disclosure, the average particle size of the particles refers to the 50% (median) diameter (D50) obtained from the volume distribution of the particle size distribution measured by 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.).

[0020] The amount of a specific metal compound contained in the resin composition is not particularly limited and can be selected according to the desired properties of the layer obtained by curing the resin composition. From the viewpoint of the initial rust prevention effect and the stability of the initial friction properties of the layer obtained by curing the resin composition, the amount of the specific metal compound contained in the resin composition is preferably 10% by mass or more of the total solid content contained in the resin composition, more preferably 20% by mass or more, and even more preferably 30% by mass or more. From the viewpoint of the strength of the layer obtained by curing the resin composition, the amount of the specific metal compound contained in the resin composition is preferably 90% by mass or less of the total solid content contained in the resin composition, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0021] (Epoxy Compounds) The resin compositions of this disclosure include epoxy compounds. In this disclosure, an epoxy compound means a compound containing one or more epoxy groups in its molecule. From the viewpoint of polymerization reactivity, it is preferable that the epoxy compound included in the resin composition contains two or more epoxy groups in its molecule. The resin compositions of this disclosure harden by a polymerization reaction of the epoxy compound to form a cured product. The method for hardening the resin compositions of this disclosure is not particularly limited, but from the viewpoint of work efficiency in rust prevention treatment, it is preferable to harden by heating.

[0022] By including an epoxy compound along with a specific metal compound in the resin composition, the shedding of the specific metal compound from the layer obtained by curing the resin composition can be suppressed, and the rust-preventive effect of the layer can be well maintained.

[0023] Specifically, the epoxy compounds included in the resin composition include: novolac-type epoxy compounds (phenol novolac-type epoxy compounds, orthocresol novolac-type epoxy compounds, etc.) which are obtained by condensing or co-condensing a compound having a phenolic hydroxyl group (hereinafter also called a phenol compound) with an aliphatic aldehyde compound such as formaldehyde, acetaldehyde, or propionaldehyde under an acidic catalyst and then epoxidizing the novolac compound; triphenylmethane-type epoxy compounds which are obtained by condensing or co-condensing a phenolic compound with an aromatic aldehyde compound such as benzaldehyde or salicylaldehyde and then epoxidizing the triphenylmethane-type phenol compound; bisphenol-type epoxy compounds which are diglycidyl ethers of bisphenol compounds such as bisphenol A and bisphenol F; biphenyl-type epoxy compounds which are diglycidyl ethers of alkyl-substituted or unsubstituted biphenols; stilbene-type epoxy compounds which are diglycidyl ethers of stilbene-based phenol compounds; and diglycidyl ethers of bisphenol S, etc. Epoxy compounds containing sulfur atoms that are zyl ethers; epoxy compounds that are glycidyl ethers of alcohols such as butanediol, polyethylene glycol, and polypropylene glycol; glycidyl ester type epoxy compounds that are glycidyl esters of polycarboxylic acid compounds such as phthalic acid, isophthalic acid, and tetrahydrophthalic acid; glycidylamine type epoxy compounds in which the active hydrogen bonded to the nitrogen atom of aniline, diaminodiphenylmethane, isocyanuric acid, etc., is substituted with a glycidyl group; dicyclopentadiene type epoxy compounds that are epoxidized from a co-condensation compound of dicyclopentadiene and a phenol compound; alicyclic epoxy compounds such as vinylcyclohexene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and 2-(3,4-epoxy)cyclohexyl-5,5-spiro(3,4-epoxy)cyclohexane-m-dioxane, in which the intramolecular olefin bond is epoxidized; paraxylylene-modified epoxy compounds that are glycidyl ethers of paraxylylene-modified phenol compounds;Examples of epoxy compounds include: metaxylylene-modified epoxy compounds, which are glycidyl ethers of metaxylylene-modified phenol compounds; terpene-modified epoxy compounds, which are glycidyl ethers of terpene-modified phenol compounds; dicyclopentadiene-modified epoxy compounds, which are glycidyl ethers of dicyclopentadiene-modified phenol compounds; cyclopentadiene-modified epoxy compounds, which are glycidyl ethers of cyclopentadiene-modified phenol compounds; polycyclic aromatic ring-modified epoxy compounds, which are glycidyl ethers of polycyclic aromatic ring-modified phenol compounds; naphthalene-type epoxy compounds, which are glycidyl ethers of naphthalene ring-containing phenol compounds; halogenated phenol novolac-type epoxy compounds; hydroquinone-type epoxy compounds; trimethylolpropane-type epoxy compounds; linear aliphatic epoxy compounds obtained by oxidizing olefin bonds with peracids such as peracetic acid; and aralkyl-type epoxy compounds, which are epoxidized aralkyl-type phenol compounds such as phenol aralkyl compounds and naphthol aralkyl compounds. Furthermore, epoxides of silicone compounds and epoxides of acrylic resins can also be cited as epoxy compounds. The epoxy compounds contained in the resin composition may be one type or two or more types.

[0024] From the viewpoint of being easily available, easy to handle, and enabling a variety of coating forms for the resin composition, bisphenol-type epoxy compounds are preferred as the epoxy compounds included in the resin composition, and bisphenol A-type or bisphenol F-type epoxy compounds are more preferred.

[0025] From the viewpoint of exhibiting sufficient thermosetting properties, the epoxy equivalent of the epoxy compound is preferably 1500 g / eq or less, preferably 1200 g / eq or less, and more preferably 1000 g / eq or less. The lower limit of the epoxy equivalent of the epoxy compound is not particularly limited. From the viewpoint of balancing the physical properties of the layer obtained by curing the resin composition, the epoxy equivalent of the epoxy compound may be 100 g / eq or more, 200 g / eq or more, or 500 g / eq or more. The epoxy equivalent of the epoxy resin shall be a value measured by a method in accordance with JIS K 7236:2009.

[0026] From the viewpoint of good dispersion of a specific metal compound in a layer obtained by curing a resin composition, it is preferable that the epoxy compound contained in the resin composition is dissolved or dispersed in water. Examples of epoxy compounds dissolved in water include epoxy compounds having hydrophilic functional groups, such as glycerol polyglycidyl ether. Examples of epoxy compounds dispersed in water include bisphenol-type epoxy compounds.

[0027] The amount of epoxy compound contained in the resin composition is not particularly limited and can be selected according to the desired properties of the layer obtained by curing the resin composition. For example, the amount of epoxy compound contained in the resin composition may be selected from 10% to 75% by mass of the total solid content contained in the resin composition.

[0028] The mass ratio of the total amount of epoxy compounds to the total amount of specific metal compounds (epoxy compound / specific metal compound) may be in the range of 0.2 to 10, 0.5 to 8, or 1 to 5, from the viewpoint of suppressing the shedding and fading of the specific metal compounds. In this disclosure, "fade" refers to the phenomenon in which the resin component turns into tar due to heating. The occurrence of fade may cause a decrease in the coefficient of friction on the sliding surface of the brake rotor.

[0029] (Water) The resin composition of this disclosure contains water. The amount of water contained in the resin composition is not particularly limited and can be selected according to the desired viscosity of the resin composition. For example, the amount of water contained in the resin composition may be selected from 15% to 95% by mass of the total resin composition.

[0030] (Other components) If necessary, the resin compositions of this disclosure may contain components other than certain metal compounds, epoxy compounds, and water. For example, the resin compositions of this disclosure may contain curing agents, curing accelerators, etc.

[0031] As a curing agent, any known curing agent containing active hydrogen that can react with epoxy compounds can be used without particular limitation. For example, phenol compounds, acid anhydrides, amine compounds, etc., can be used as curing agents. Examples of phenol compounds include phenol novolac compounds, cresol novolac compounds, and phenol aralkyl compounds. Examples of acid anhydrides include docecenyl succinic anhydride, polyazelaic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic anhydride. Specific examples of amine compounds include aliphatic amine compounds, aromatic amine compounds, dicyandiamide, and melamine. The resin composition may contain only one or more curing agents. From the viewpoint of promoting good curing of the resin composition, it is preferable that the curing agent contained in the resin composition is dissolved or dispersed in water, and more preferably dissolved in water.

[0032] When the resin composition contains a curing agent, the equivalent ratio of the epoxy compound to the curing agent (epoxy compound / curing agent) is preferably 0.4 to 2.0, and more preferably 0.6 to 1.2, from the viewpoint of sufficiently curing the resin composition.

[0033] Examples of curing accelerators included in the resin composition include imidazole compounds, tertiary amine compounds, and phosphorus compounds. Examples of imidazole compounds include imidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, and 1-(2-cyanoethyl)-2-phenylimidazole. Examples of tertiary amine compounds include benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo[5.4.0]undeca-7-ene, and hexamethylenetetramine. Examples of phosphorus compounds include triphenylphosphine. The resin composition may contain only one or two or more curing accelerators. From the viewpoint of effectively promoting the curing properties of the resin composition, it is preferable that the curing accelerators included in the resin composition be dissolved or dispersed in water, and more preferably dissolved in water.

[0034] In one embodiment, the resin composition may contain an imidazole compound and hexamethylenetetramine as curing accelerators. Resin compositions containing an imidazole compound and hexamethylenetetramine tend to lower the temperature at which the polymerization reaction of the epoxy compound occurs. Lowering the temperature at which the polymerization reaction of the epoxy compound occurs allows the process of heating the resin composition applied to the sliding surface of the brake rotor to form a layer to be carried out at a lower temperature. As a result, energy required for the rust prevention treatment of the brake rotor can be saved, and manufacturing costs can be reduced. The resin composition may also contain an imidazole compound selected from imidazole, 2-methylimidazole, and 2-ethyl-4-methylimidazole, and hexamethylenetetramine as curing accelerators. Since these compounds are readily soluble in water, they become dissolved in water in the resin composition of this disclosure and can effectively promote the polymerization reaction of the epoxy compound.

[0035] When the resin composition contains a curing accelerator, it is preferable that the amount of the accelerator is 0.1 to 10 parts by mass per 100 parts by mass of the epoxy compound, from the viewpoint of ensuring a smooth curing reaction of the resin composition and obtaining a cured product with excellent strength.

[0036] If necessary, the resin composition may also contain components such as organic solvents, polymerization initiators, crosslinking agents, sensitizers, friction modifiers, viscosity modifiers, elastic modifiers, surfactants, leveling agents, rust inhibitors, thickeners, colorants, metal deactivators, fragrances, and resins.

[0037] Examples of organic solvents include alcohol-based solvents, glycol-based solvents, ester-based solvents, ketone-based solvents, ether-based solvents, and aromatic solvents. Among these, alcohol-based solvents are preferred from the viewpoint of miscibility with water. When the resin composition contains an organic solvent, the amount is preferably 15% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less, of the total liquid medium (sum of water and organic solvent) contained in the resin composition. It is preferable that the resin composition does not contain an organic solvent.

[0038] The temperature at which the curing reaction of the resin composition occurs (curing temperature) is not particularly limited and can be selected according to the method of use of the resin composition. From the viewpoint of manufacturing brake rotors in a low-cost and safe manner, the curing temperature of the resin composition is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. From the viewpoint of the handling of the resin composition, the curing temperature of the resin composition is preferably 80°C or higher, more preferably 90°C or higher, and even more preferably 100°C or higher.

[0039] [Brake Rotor] The brake rotor of the present disclosure has a layer containing a cured product of the resin composition of the present disclosure on the sliding surface. The brake rotor of the present disclosure is excellent in the initial rust prevention effect and the stability of the initial friction coefficient. The reason is presumed as follows. The layer containing the cured product of the resin composition contains a specific metal compound. Therefore, before the start of use of the brake rotor, an excellent rust prevention effect is exhibited. Furthermore, after the start of use of the brake rotor, due to the friction with the brake pad, a part of the specific metal compound contained in the layer penetrates into the fine uneven structure on the surface of the brake rotor, and a dense layer is formed on the sliding surface. As a result, excellent stability of the friction coefficient is exhibited. From the viewpoint of easily forming a dense layer on the sliding surface of the brake rotor by friction with the brake pad, the layer containing the cured product of the resin composition preferably contains a titanium compound as the specific metal compound.

[0040] Since the generation of rust on the sliding surface before the start of use of the brake rotor of the present disclosure is suppressed, the cured product of the resin composition enters between the brake rotor and the friction material, and the contact area between them increases. Therefore, the number of times of braking repeated until the friction coefficient after the start of use of the brake rotor reaches a predetermined value can be reduced. As a result, for example, even in a vehicle with a small normal brake load such as an electric vehicle, a stable braking force can be obtained early.

[0041] The brake rotor of the present disclosure is used, for example, as a component of a vehicle brake. The type of vehicle is not particularly limited, and examples include automobiles (including motorcycles), bicycles, railway vehicles, and the like. The brake rotor of the present disclosure may be a brake rotor (disc rotor) of a disc brake.

[0042] The material of the main body of the brake rotor is not particularly limited. In one embodiment, the main body of the brake rotor contains iron and may be subjected to at least one surface treatment such as grinding, polishing, and machining. Examples of brake rotors containing iron include cast iron brake rotors. In the present disclosure, cast iron means an iron alloy containing carbon in the range of 2.14% to 6.67% by mass. The method of performing the surface treatment is not particularly limited and can be selected from known methods. An example of machining is roller burnishing. The surface treatment may be applied to all or part of the surface of the brake rotor.

[0043] The layer disposed on the sliding surface of the brake rotor contains a specific metal compound. The amount of the specific metal compound contained in the layer per unit area is not particularly limited. From the viewpoint of exhibiting a sufficient rust prevention effect and stable friction characteristics, the amount of the specific metal compound per unit area is preferably 0.01 mg / cm ２ or more, and more preferably 0.2 mg / cm ２ or more. From the viewpoint of suppressing the dropout of the specific metal compound from the layer, the amount of the specific metal compound per unit area is preferably 25 mg / cm ２ or less, and more preferably 12.5 mg / cm ２ or less.

[0044] From the viewpoint of exhibiting a sufficient rust prevention effect and stable friction characteristics, the amount of the specific metal compound contained in the layer is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more of the entire layer. From the viewpoint of suppressing the dropout of the specific metal compound from the layer, the amount of the specific metal compound contained in the layer is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less of the entire layer.

[0045] The layer disposed on the sliding surface of the brake rotor contains a polymer of an epoxy compound. By including a polymer of an epoxy compound in the layer, the dropout of the specific metal compound from the layer is suppressed and a good rust prevention effect is maintained.

[0046] The thickness of the layer placed on the sliding surface of the brake rotor is not particularly limited. From the viewpoint of achieving a sufficient rust prevention effect, the thickness of the layer is preferably 1 μm or more, more preferably 5 μm, and even more preferably 10 μm or more. From the viewpoint of stabilizing the coefficient of friction early and suppressing the occurrence of fade, the thickness of the layer is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

[0047] [Brake rotor manufacturing kit] The brake rotor manufacturing kit of this disclosure comprises the resin composition of this disclosure described above and the body of a brake rotor. In this disclosure, the body of a brake rotor means a brake rotor in which the layer obtained by curing the resin composition has not been formed on the sliding surface.

[0048] The brake rotor manufacturing kit of this disclosure is used to manufacture a brake rotor having a layer containing a cured resin composition on its sliding surface. The method for manufacturing a brake rotor using the brake rotor manufacturing kit of this disclosure may be carried out by the method described later for manufacturing a brake rotor.

[0049] [Method for Manufacturing a Brake Rotor] The method for manufacturing a brake rotor according to the present disclosure includes applying the above-described resin composition to the sliding surface of the body of the brake rotor, and curing the resin composition to form a layer containing the cured resin composition on the sliding surface.

[0050] The method for applying the resin composition of this disclosure to the sliding surface of the brake rotor body is not particularly limited and can be carried out using known means such as a dispenser, spray, cast coater, or spin coater.

[0051] The method for curing the resin composition applied to the sliding surface of the brake rotor body is not particularly limited. For example, the resin composition can be cured by heating it to a temperature at which polymerization of the epoxy compounds contained in the resin composition occurs. The heating temperature (maximum temperature) can be, for example, 200°C or less, 180°C or less, 160°C or less, 150°C or less, 140°C or less, or 130°C or less. The method for heating the resin composition is not particularly limited and can be carried out using known apparatus.

[0052] Before curing the resin composition applied to the sliding surface of the brake rotor body, a drying treatment may be performed to remove water and, if necessary, organic solvents contained in the resin composition. The drying treatment may include heating the resin composition. The heating temperature can be set considering the boiling points of the water and, if necessary, organic solvents contained in the resin composition.

[0053] [Brake] The brake of this disclosure comprises the brake rotor of this disclosure described above and brake pads. More specifically, it comprises the brake rotor of this disclosure described above and a pair of brake pads that sandwich the brake rotor. The brake of this disclosure may also comprise a disc rotor and disc brake pads. The brake of this disclosure may be used in automobiles (including motorcycles), bicycles, railway vehicles, etc.

[0054] The brake pads included in the brake system of this disclosure can be any commonly used brake pads without particular limitation. The brake pad includes, for example, a friction material that contacts the sliding surface of the brake rotor and a base plate. Specific examples of brake pads include steel pads, semi-steel pads, organic material pads, and a preferred example is a non-asbestos organic material pad. The brake pad may further include, between the base plate and the friction material, a primer layer for surface modification to enhance the adhesion effect of the base plate to the friction material, an adhesive layer for bonding the base plate and the friction material, and so on.

[0055] The present disclosure will be described in further detail below with reference to examples, but the present disclosure is not limited in any way by these examples.

[0056] <Example 1> (Preparation of Resin Composition 1) Resin composition 1 was obtained by mixing the following materials with 21 g of water. The amounts of aqueous dispersion shown below are the amounts containing water. Aqueous dispersion of rutile-type titanium dioxide (concentration: approximately 71% by mass): 4.0 g Aqueous dispersion of bisphenol A type liquid epoxy compound (product name: Adeka Resin EM-051R, manufactured by ADEKA Corporation, epoxy equivalent: 650 g / eq, non-volatile component concentration: approximately 50% by mass): 5.8 g Aqueous dispersion of carbon as a colorant (concentration: approximately 32% by mass): 453 mg Hexamethylenetetramine: 159 mg 2-ethyl-4-methylimidazole: 159 mg Calcium hydroxide as a rust inhibitor (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 286 mg Zinc phosphate monohydrate as a rust inhibitor (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 286 mg Thickener (product name: Adekanol UH-420, manufactured by ADEKA Corporation): 79 mg

[0057] A brake rotor made of cast iron (FC250) with a diameter of 280 mm and a thickness of 28 mm was prepared for use in the friction evaluation described later. The outer surface (tire side) of the brake rotor was preheated to approximately 130°C, and approximately 11 g of resin composition 1 was spray-coated evenly to the outer surface of the brake rotor. Then, the brake rotor was heated in a hot air dryer at approximately 130°C for 10 minutes. Next, the inner surface (opposite side of the outer surface) of the brake rotor was preheated to approximately 130°C, and approximately 11 g of resin composition 1 was spray-coated evenly to the inner surface of the brake rotor. Then, the brake rotor was heated in a hot air dryer at approximately 130°C for 10 minutes. Through the above steps, a brake rotor was obtained in which layers (thickness: approximately 20 μm) containing cured resin composition 1 were formed on the outer surface and the inner surface, respectively.

[0058] (Friction evaluation test) The friction evaluation test uses a test pad (HP69H, Resonaq Corporation, pad area: 60 cm²). ２The aforementioned test pads, a brake rotor with a layer containing the cured resin composition 1 formed on it, and a brake dynamometer (manufactured by Shin Nippon Tokki Co., Ltd.) were used to conduct friction evaluation tests under conditions of 20°C and 60% humidity. Specifically, tests were conducted in which the brakes were repeatedly applied under conditions of an initial speed of 40 km / h and a deceleration of 1.5 m / sec. The coefficient of friction from the start to the end (stop) of the 1st, 50th, 100th, and 200th brake applications was measured continuously, and the average value was calculated as the average coefficient of friction. The results are shown in Table 1.

[0059] (Corrosion Prevention Evaluation Test) Resin composition 1 was spray-coated onto one side of a cast iron (FC250) brake rotor (64 mm in diameter), and heated in a hot air dryer at approximately 130°C for 10 minutes to form a layer (approximately 25 μm thick) containing the cured resin composition 1. A 2 cm high spacer was placed in a plastic case with air holes at the top in the direction of gravity, and the brake rotor was placed on the spacer. The brake rotor was positioned so that the side of the brake rotor that did not have the layer containing the cured resin composition 1 facing the spacer. Next, water was added to the plastic case to a height of 1 cm, and the test was started by leaving the plastic case filled with water undisturbed in an environment of 23°C. The occurrence of rust on the surface where the layer containing the cured resin composition 1 was formed was observed at the start of the test (day 0), and 1 day and 7 days after the start of the test. The results are shown in Table 1.

[0060] <Example 2> Resin composition 2 was obtained by mixing the following materials with 21 g of water. The amounts of aqueous dispersions shown below include the amount of water. Aqueous dispersion of rutile titanium dioxide (concentration: approximately 71% by mass): 4.0 g Aqueous dispersion of aqueous epoxy compound (product name: Adeka Resin EM-434AN, manufactured by ADEKA Corporation, non-volatile components: approximately 31% by mass): 9.4 g Aqueous dispersion of carbon as a colorant (concentration: approximately 32% by mass): 453 mg Calcium hydroxide as a rust inhibitor (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 286 mg Zinc phosphate monohydrate as a rust inhibitor (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.): 286 mg Thickening agent (product name: Adekanol UH-420, manufactured by ADEKA Corporation): 79 mg

[0061] The outer surface of the same brake rotor used in Example 1 was preheated to approximately 130°C, and approximately 12 g of resin composition 2 was spray-coated evenly to the outer surface of the brake rotor. Then, the brake rotor was heated in a hot air dryer at approximately 130°C for 10 minutes. Next, the inner surface of the brake rotor was preheated to approximately 130°C, and approximately 12 g of resin composition 2 was spray-coated evenly to the inner surface of the brake rotor. Then, the brake rotor was heated in a hot air dryer at approximately 130°C for 10 minutes. Through the above steps, a brake rotor was obtained in which layers (thickness: approximately 20 μm) containing cured resin composition 2 were formed on the outer and inner surfaces. Next, friction evaluation tests and rust prevention evaluation tests of the brake rotor were performed in the same manner as in Example 1. The results are shown in Table 1.

[0062] <Comparative Example 1> A brake rotor used in Example 1 was subjected to friction evaluation tests and rust prevention evaluation tests in the same manner as in Example 1, but without forming a layer containing the cured resin composition 1. The results are shown in Table 1.

[0063]

[0064] The average friction coefficient shown in "1st time" in Table 1 is the average friction coefficient measured during the first braking, the average friction coefficient shown in "50th time" is the average friction coefficient measured during the 50th braking, the average friction coefficient shown in "100th time" is the average friction coefficient measured during the 100th braking, and the average friction coefficient shown in "200th time" is the average friction coefficient measured during the 200th braking.

[0065] As shown in the friction evaluation test results, the brake rotors of Examples 1 and 2, which had layers containing the cured resin composition of this disclosure, showed a high coefficient of friction from the initial stage immediately after the start of the test. Furthermore, the fluctuation in the coefficient of friction when the number of braking cycles was increased was relatively small and within an acceptable range.

[0066] As shown in the results of the rust prevention evaluation test, the brake rotors of Examples 1 and 2, which had layers containing the cured resin composition of this disclosure, showed no rust formation for 7 days after the layer was formed, demonstrating excellent initial rust prevention effect.

Claims

1. A resin composition comprising at least one metal compound selected from the group consisting of titanium compounds, magnesium compounds, and lithium compounds, an epoxy compound, and water, used for coating the sliding surface of a brake rotor.

2. The resin composition according to claim 1, wherein the metal compound comprises a titanium compound.

3. The resin composition according to claim 2, wherein the titanium compound comprises at least one selected from the group consisting of titanium oxide and titanium black.

4. The resin composition according to claim 1, wherein the epoxy compound is dissolved or dispersed in water.

5. The resin composition according to claim 1, wherein the epoxy compound comprises a bisphenol-type epoxy compound.

6. The resin composition according to claim 1, which hardens at a temperature of 150°C or lower.

7. The resin composition according to claim 1, further comprising a curing accelerator for epoxy compounds, wherein the curing accelerator is dissolved in water.

8. The resin composition according to claim 1, further comprising an imidazole compound and hexamethylenetetramine.

9. A brake rotor having a sliding surface comprising a layer containing a cured resin composition according to any one of claims 1 to 8.

10. The brake rotor according to claim 9, wherein the thickness of the layer is 1 μm to 100 μm.

11. A kit for manufacturing a brake rotor, comprising a resin composition according to any one of claims 1 to 8, and a brake rotor body.

12. A method for manufacturing a brake rotor, comprising: applying a resin composition according to any one of claims 1 to 8 to the sliding surface of the body of the brake rotor; and curing the resin composition to form a layer containing a cured product of the resin composition on the sliding surface.

13. A brake comprising the brake rotor and brake pad described in claim 9.

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