Coating agent

Abstract

A coating agent comprising: (A) a resin having a film-forming property; (B) silicone rubber particles which are an addition reaction product of a curable liquid silicone composition containing the following components; and water, (B-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule; (B-2) an organopolysiloxane resin containing R13SiO1 / 2 units and SiO4 / 2 units, the molar ratio of the R13SiO1 / 2 units to the SiO4 / 2 units being 0.60-1.7 (in the formula, R1 each independently represents a substituted or unsubstituted monovalent hydrocarbon group having 1-30 carbon atoms and not having an alkenyl group, or an alkenyl group having 2-8 carbon atoms, and at least one of all R1 represents an alkenyl group); and (B-3) an organohydrogenpolysiloxane having two or more silicon atom-bonded hydrogen atoms per molecule, the amount of component (B-2) being 1.0-65 parts by mass per 100 parts by mass of the total of component (B-1), component (B-2), and component (B-3), and the mass ratio of component (A) to component (B) being 85: 15-25: 75 in the coating agent.

Description

Technical Field

[0001] The present invention relates to a coating agent, and more particularly to an aqueous coating agent for a rubber material that provides a hardened film having excellent wear resistance and surface smoothness to a base material composed of the rubber material. Background Art

[0002] Conventionally, in order to impart surface smoothness, abrasion resistance, water repellency, antifouling properties, and anti-adhesion properties to various rubbers, a method of coating the surface with a silicone-based aqueous composition or a urethane-based aqueous composition and curing the composition has been used.

[0003] In order to improve the surface smoothness and wear resistance, Patent Document 1 proposes to mix spherical silicone rubber particles in a film-forming water-based silicone composition. The light scattering property of the particles can also impart matte properties to the coating film. However, the wear resistance to friction under load is not sufficient.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 11-49955

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating agent, particularly an aqueous coating agent for rubber, which forms a coating film having excellent surface smoothness and wear resistance even against high-load friction. Summary of the invention

[0008] Technical means of solving problems

[0009] The present inventors have conducted intensive research to achieve the above object and have concluded that silicone rubber particles in the coating film are broken by load. The present inventors have found that the above object can be achieved by mixing silicone rubber particles having high rubber strength and high elongation into the coating agent, thereby completing the present invention.

[0010] Specifically, it has been found that the above problems can be solved by blending silicone rubber particles into a coating agent containing a film-forming resin, wherein the silicone rubber particles are an addition reaction product of a silicone composition obtained by further blending an organopolysiloxane resin having an alkenyl group into a composition containing a diorganopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane having silicon-bonded hydrogen as raw materials.

[0011] That is, the present invention provides the following coating agent.

[0012] A coating agent comprising: (A) a resin having film-forming properties;

[0013] (B) silicone rubber particles, which are an addition reaction product of a curable liquid silicone composition comprising the following components (B-1), (B-2) and (B-3); and

[0014] water,

[0015] (B-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule,

[0016] (B-2) an organopolysiloxane resin containing R 1 3SiO 1 / 2 Unit and SiO 4 / 2 Unit, R 1 3SiO 1 / 2 Unit relative to SiO 4 / 2 The molar ratio of the unit is 0.60 to 1.7 (in the formula, R 1 are independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and all R 1 is alkenyl), and

[0017] (B-3) organohydrogenpolysiloxane, having two or more silicon-bonded hydrogen atoms (called SiH groups) in one molecule,

[0018] The amount of the component (B-2) is 1.0 to 65 parts by mass relative to 100 parts by mass of the total of the components (B-1), (B-2) and (B-3).

[0019] In the coating agent, the mass ratio of the component (A) to the component (B) is 85:15 to 25:75.

[0020] The present invention also provides a coating agent, which further has at least one feature selected from the following [1] to [9].

[0021] [1] The coating agent according to claim 1, wherein the (B-1) diorganopolysiloxane has an alkenyl group content of 0.0025 mol / 100 g to 0.034 mol / 100 g, the (B-2) organopolysiloxane resin has an alkenyl group content of 0.001 mol / 100 g or more, and the (B-3) organohydrogenpolysiloxane has an SiH group content of 0.030 mol / 100 g to 1.30 mol / 100 g.

[0022] [2] According to the coating agent, wherein the amount of (A) the resin having film-forming properties is 0.5 to 59 parts by mass, the amount of (B) the silicone rubber particles is 0.3 to 52 parts by mass, and the amount of water is 30 to 98 parts by mass, relative to 100 parts by mass of the coating agent.

[0023] [3] The coating agent according to the present invention, wherein the silicone rubber particles have a volume average particle size of 0.5 μm to 50 μm and are spherical.

[0024] [4] The coating agent described above, comprising an emulsion of the resin having film-forming properties.

[0025] [5] According to the coating agent, the resin having film-forming properties is at least one selected from urethane resin, vinyl chloride resin, acrylic resin, silicone-acrylic copolymer resin, silicone-urethane copolymer resin, styrene-butadiene-acrylonitrile resin, polyester resin, amide resin, and silicone rubber.

[0026] [6] The coating agent according to the above-mentioned embodiment, wherein the resin having film-forming properties is at least one selected from the group consisting of urethane resins, silicone rubbers, and silicone-urethane copolymer resins.

[0027] [7] The coating agent according to the above-mentioned coating agent, wherein the amount of the silicone rubber particles in the aqueous dispersion containing the silicone rubber particles is 5% by mass to 70% by mass based on the mass of the aqueous dispersion.

[0028] [8] According to the coating agent, the silicone rubber particles contain the following silicone rubber: for a rubber sheet with a thickness of 1 mm that has been heat treated at 150°C for 30 minutes, the elongation at break of a dumbbell-shaped No. 3 test piece measured in accordance with Japanese Industrial Standards (JIS) K 6251:2017 is 15% or more, and the tensile strength at break measured in accordance with JIS K 6251:2017 is 0.9 MPa or more.

[0029] [9] According to the coating agent, it is a coating agent for rubber materials.

[0030] Effects of the Invention

[0031] The coating agent of the present invention can form a film having excellent surface smoothness and wear resistance even against high-load friction. Therefore, the aqueous coating agent for rubber of the present invention can be used for the purpose of improving the sliding property, wear resistance and antifouling property of rubber rollers and preventing adhesion of O-rings, packings, gaskets, etc., and is particularly effective for improving the wear resistance, improving the sliding property and preventing squeaking of weather stripping rubber around car doors or trucks. DETAILED DESCRIPTION

[0032] Hereinafter, the present invention will be described in detail.

[0033] [(A) ingredient]

[0034] The component (A) of the present invention is an emulsion of a film-forming resin. The film-forming resin refers to a resin that can form a solid film by volatilizing water in the emulsion or by heat treatment.

[0035] The solid content of the emulsion of the resin (A) is not particularly limited, but is preferably 5% to 80% by mass, more preferably 20% to 60% by mass, relative to the mass of the emulsion. The dispersion medium of the emulsion is preferably water.

[0036] The emulsion of the resin (A) may contain an anionic surfactant or a nonionic surfactant. If the resin is self-emulsifying, it may not contain a surfactant.

[0037] In order to make the emulsion of the resin (A) have the ability to form a film, the volume average particle size of the resin is preferably small. Specifically, it is 5nm to 1000nm, more preferably 50nm to 500nm, and even more preferably 100nm to 400nm. In addition, in the present invention, the volume average particle size of the resin is measured using a laser diffraction / scattering particle size measuring device.

[0038] The film formed by the emulsion of the resin preferably has an elongation of 50% or more when cut and a tensile strength of 1.0 MPa or more when cut. If the elongation is low when cut, the film will break when the coated base rubber is deformed. It is more preferably 100% or more, and more preferably 200% or more. If the tensile strength is low when cut, the wear resistance of the film of the coating agent decreases. It is more preferably 1.5 MPa or more, and more preferably 2.0 MPa or more.

[0039] In the present invention, the elongation at break and the tensile strength at break are values ​​measured by the test method specified in JIS K 6251 on a dumbbell No. 3 test piece having a thickness of 1 mm and heat-treated at 150° C. after volatilization and removal of water.

[0040] The resin emulsion having film forming properties may be a conventionally known film forming resin. For example, emulsions of urethane resin, vinyl chloride resin, acrylic resin, silicone-acrylic copolymer resin, silicone-urethane copolymer resin, styrene-butadiene-acrylonitrile resin, polyester resin, amide resin, and silicone rubber may be cited. Preferably, urethane resin emulsion, silicone rubber emulsion, or silicone-urethane copolymer resin is used. Two or more emulsions of different resin types may be used in combination.

[0041] [(B) ingredient]

[0042] The component (B) of the present invention is a water dispersion of silicone rubber particles. The component (B) does not have the ability to form a film.

[0043] The particle shape of the aqueous dispersion (B) of silicone rubber particles is preferably spherical. In this specification, the so-called "spherical" means that the particle shape is not only a sphere, but also a deformed sphere whose average length of the longest axis / length of the shortest axis (aspect ratio) is usually 1.0 to 4.0, preferably 1.0 to 2.0, more preferably 1.0 to 1.6, and even more preferably 1.0 to 1.4. The particle shape can be confirmed by observing the particles using an optical microscope, an electron microscope, etc. In addition, it can be measured by a particle shape analysis device using a dynamic image analysis method.

[0044] The volume average particle size of the particles may be 0.5 μm to 50 μm. If the particle size is small, the surface smoothness of the obtained film is low, and if the particle size is large, the wear resistance may be deteriorated. Preferably, it is 1.0 μm to 30 μm, more preferably 1.5 μm to 20 μm, and even more preferably 1.9 μm to 15 μm. In the present invention, the volume average particle size of the silicone rubber particles is measured by a Coulter counter method (resistance method).

[0045] The silicone rubber of the silicone rubber particles is an addition reaction product of a curable liquid silicone composition, wherein the curable liquid silicone composition comprises (B-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule, (B-2) an organopolysiloxane resin having alkenyl groups, and (B-3) an organohydrogenpolysiloxane having two or more SiH groups in one molecule.

[0046] The diorganopolysiloxane having two or more alkenyl groups in one molecule of the component (B-1) is represented by the following average composition formula (1).

[0047] R 2 a R 3 b SiO (4-a-b) / 2 (1)

[0048] In the formula, R 2 are independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms and not having an alkenyl group, R 3 Each is independently an alkenyl group having 2 to 8 carbon atoms, and a and b are positive numbers satisfying 0<a<3, 0<b≦3, and 0.1≦a+b≦3.

[0049] The diorganopolysiloxane represented by the average composition formula (1) may be used alone or in combination of two or more.

[0050] R 2It is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms, preferably a monovalent hydrocarbon group having 1 to 22 carbon atoms, and more preferably a monovalent hydrocarbon group having 1 to 18 carbon atoms.

[0051] As R 2 , for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, decyl, undecyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, triacontyl, etc.; aryl groups such as phenyl, tolyl, naphthyl, etc.; aralkyl groups such as benzyl, phenethyl, etc.; cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, etc.; and hydrocarbon groups in which a part or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with atoms such as halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms) and / or substituents such as acryloyloxy, methacryloyloxy, amino, epoxy, glycidyloxy, carboxyl, etc. Preferably, all R 2 50 mol % or more of the groups are methyl groups.

[0052] R 3 Examples thereof include a vinyl group, an allyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, and an octenyl group. A vinyl group, an allyl group, and a hexenyl group are preferred, and a vinyl group is more preferred.

[0053] a and b are preferably positive numbers satisfying 0<a≦2.295, 0.005≦b≦2.3, and 0.5≦a+b≦2.3.

[0054] In the silicone rubber particles, the alkenyl content of component (B-1) is preferably 0.0025 mol / 100 g to 0.034 mol / 100 g. If it is more than 0.034 mol / 100 g, the strength or elongation of the silicone rubber may be reduced. If it is less than 0.0025 mol / 100 g, it becomes a structure with a high degree of polymerization, so the viscosity becomes high, and the viscosity of the curable liquid silicone containing components (B-2) and (B-3) becomes high, and the emulsification described later may become difficult. It is more preferably 0.0030 mol / 100 g to 0.027 mol / 100 g, and even more preferably 0.0035 mol / 100 g to 0.020 mol / 100 g.

[0055] The viscosity of the component (B-1) at 25°C is preferably 100,000 mm 2 / s or less, more preferably 50,000 mm 2 / s or less. If the viscosity is higher than 100,000mm 2 / s, the viscosity of the curable liquid silicone containing the components (B-2) and (B-3) becomes high, and the emulsification described later may become difficult. The lower limit of the viscosity is not particularly limited, but is less than about 130 mm2 / s, it is difficult for the olefin content to be less than 0.034 mol / 100 g, so as long as 130 mm 2 / s or more, especially 200mm 2 / s or more.

[0056] The structure of the component (B-1) may be any of linear, cyclic and branched, and is particularly preferably linear or branched with fewer branch units. The bonding site of the alkenyl group is not particularly limited, and may be bonded to a silicon atom at any of the side chain and the terminal of the molecule.

[0057] Examples of the linear structure include a structure represented by the following general formula (2).

[0058] [Chemistry 1]

[0059]

[0060] In the formula, R 2 , R 3 As described above, c is a positive number of 10 to 1,500, preferably a positive number of 30 to 1,200, more preferably a positive number of 50 to 950, and further preferably a positive number of 80 to 800, d is a positive number of 0 or less, and e is 0, 1, 2 or 3, wherein d and e are numbers satisfying d+2×e≧2.

[0061] Examples of the branched structure include: 2 SiO 3 / 2 The structure represented by the following general formula (3) is branched by units.

[0062] [Chemistry 2]

[0063]

[0064] In the formula, R 2 , R 3 As described above, f is a positive number of 10 to 1,500, preferably a positive number of 30 to 1,200, more preferably a positive number of 50 to 950, and further preferably a positive number of 80 to 800, g is a positive number of 0 or 50, h is a positive number of 1 to 10, and i is 0, 1, 2 or 3, wherein g and i are numbers satisfying g+i≧1.

[0065] As SiO 4 / 2 An example of a structure branched by a unit of the present invention is the structure represented by the following general formula (4).

[0066] [Chemistry 3]

[0067]

[0068] In the formula, R 2 , R 3 As described above, j is a positive number of 10 to 1,500, preferably a positive number of 30 to 1,200, more preferably a positive number of 50 to 950, and further preferably a positive number of 80 to 800, k is a positive number of 0 or 50, l is a positive number of 1 to 5, and m is 0, 1, 2 or 3, wherein k and m are numbers satisfying k+m≧1.

[0069] (B-2) component contains R 1 3SiO 1 / 2 Unit and SiO 4 / 2 It is an organopolysiloxane resin having alkenyl groups and having 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 3

[0070] In the formula, R 1 Each of R is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or an alkenyl group having 2 to 8 carbon atoms. 1 At least one of the organopolysiloxane resins may be used alone, or two or more may be used in combination.

[0071] The monovalent hydrocarbon group not having an alkenyl group has a carbon number of 1 to 30, preferably 1 to 20, and more preferably 1 to 10. Examples of the monovalent hydrocarbon group not having an alkenyl group include R 2 The exemplified groups are preferably all R 2 50 mol % or more of the groups are methyl groups.

[0072] Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, allyl, propenyl, butenyl, pentenyl and hexenyl. Preferred are vinyl and allyl, and more preferred are vinyl.

[0073] In organopolysiloxane resin, R 1 3SiO 1 / 2 unit (hereinafter referred to as M unit) and SiO 4 / 2 The molar ratio of the units (hereinafter referred to as Q units) (ie, [mole of M units] / [mole of Q units]) is 0.60 to 1.7, preferably 0.65 to 1.3, and more preferably 0.70 to 1.1.

[0074] The component (B-2) may contain (R 4 O)SiO 3 / 2 Unit. In the formula, R 4 are independently a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms. (R 4 O)SiO 3 / 2 The unit is derived from the raw material. 4O groups undergo condensation reaction, but sometimes unreacted R 4 O group. Examples of the unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, and hexyl. 4 O)SiO 3 / 2 The content of the unit (referred to as Q3 unit) is preferably (R 4 O)SiO 3 / 2 Unit and SiO 4 / 2 The molar ratio of the unit [(R 4 O)SiO 3 / 2 mole of unit] / [SiO 4 / 2 That is, [mol of Q3 unit] / [mol of Q unit] is preferably 0 to 0.50, more preferably 0.01 to 0.40, and even more preferably 0.02 to 0.30.

[0075] The component (B-2) may contain R within a range that does not impair the property of forming a solid at 25° C. and the solubility in the components (B-1) and (B-3) in the production of the silicone rubber particles (A) described below. 5 SiO 3 / 2 Unit and / or R 6 2SiO 2 / 2 Unit. In the formula, R 5 and R 6 R is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms. 5 SiO 3 / 2 Unit (called T unit) and R 6 2Si 2 / 2 The content of the unit (referred to as D unit) is preferably such that [moles of T units and D units] / [moles of Q units] is 0.3 or less.

[0076] The alkenyl amount of component (B-2) is preferably 0.001 mol / 100 g or more. If it is less than 0.001 mol / 100 g, the strength or elongation of the silicone rubber becomes low. It is more preferably 0.005 mol / 100 g or more, and further preferably 0.01 mol / 100 g or more. There is no particular upper limit, but if it is more than 2.0 mol / 100 g, the molar ratio [mole of M unit] / [mole of Q unit] cannot be less than 1.7, so it only needs to be 0.8 mol / 100 g or less, especially 0.50 mol / 100 g or less.

[0077] The polystyrene-equivalent weight average molecular weight of the component (B-2) as determined by gel permeation chromatography is preferably from 1,000 to 10,000, more preferably from 2,000 to 8,000.

[0078] The organohydrogenpolysiloxane having two or more SiH groups in one molecule of the component (B-3) is preferably represented by the following average composition formula (5).

[0079] R 7 n H o SiO (4-n-o) / 2 (5)

[0080] In the formula, R 7 Each is independently an unsubstituted or substituted monovalent hydrocarbon group having 1 to 30 carbon atoms and not having an alkenyl group. n and o are numbers satisfying 0<n<3, 0<o≦3, and 0.1≦n+o≦3.

[0081] One type of the organohydrogenpolysiloxane represented by the average composition formula (5) may be used alone, or two or more types may be used in combination.

[0082] R 7 The number of carbon atoms in R is 1 to 30, preferably 1 to 22, and more preferably 1 to 18. 7 Can be listed as R 2 The exemplary monovalent hydrocarbon groups are preferably R 7 80 mol% or more of the moles are methyl groups, more preferably 95% or more of the moles are methyl groups. n and o are preferably positive numbers satisfying 0<n≦2.295, 0.005≦o≦2.3, and 0.5≦n+o≦2.3.

[0083] The amount of SiH groups in component (B-3) is preferably 0.030 mol / 100 g to 1.30 mol / 100 g. If it is less than 0.030 mol / 100 g, the strength or elongation of the silicone rubber will be reduced. If it is more than 1.30 mol / 100 g, the dispersed particles may aggregate in the aqueous dispersion of silicone rubber particles described later. It is more preferably 0.050 mol / 100 g to 1.10 mol / 100 g, and even more preferably 0.10 mol / 100 g to 0.90 mol / 100 g.

[0084] The viscosity of the component (B-3) at 25°C is preferably 100,000 mm 2 / s or less, more preferably 10,000 mm 2 / s or less. If the viscosity is 100,000mm 2 / s or less, silicone microparticles with a narrow particle size distribution can be obtained particularly easily by the production method described later. The lower limit of the viscosity is not particularly limited as long as it is 0.4 mm 2 / s or above, especially 2mm 2 / s or more. In addition, the structure of the component (B-3) may be any of a straight chain, a ring, and a branched structure, and is particularly preferably a straight chain or a branched structure. In addition, the bonding site of the hydrogen atom bonded to the silicon atom is not particularly limited, and the hydrogen atom may be bonded to the silicon atom of any of the side chain and the terminal of the molecule.

[0085] Examples of the linear structure include a structure represented by the following general formula (6).

[0086] [Chemistry 4]

[0087]

[0088] In the formula, R 7 As described above, p is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and further preferably 10 to 100, q is a positive number of 0 or 300 or less, preferably 1 to 100, and more preferably 2 to 60, and r is 0, 1, 2 or 3, wherein q and r are numbers satisfying q+2×r≧2.

[0089] Examples of the branched structure include: 7 SiO 3 / 2 The structure represented by the following general formula (7) is branched by units.

[0090] [Chemistry 5]

[0091]

[0092] In the formula, R 7 As described above, s is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and further preferably 10 to 100, t is a positive number of 0 or 300 or less, preferably 1 to 100, and more preferably 2 to 60, u is a positive number of 1 to 10, and v is 0, 1, 2 or 3, wherein t and v are numbers satisfying t+v≧1.

[0093] As SiO 4 / 2 An example of a structure in which a unit is branched is the structure represented by the following general formula (8).

[0094] [Chemistry 6]

[0095]

[0096] In the formula, R 7As described above, w is a positive number of 1,500 or less, preferably 1 to 1000, more preferably 5 to 500, and further preferably 10 to 100, x is a positive number of 0 or 300 or less, preferably 1 to 100, and more preferably 2 to 60, y is a positive number of 1 to 5, and z is 0, 1, 2 or 3, wherein x and z are numbers satisfying x+z≧1.

[0097] In addition, there can be mentioned a structure represented by the following unit formula (9) having two or more hydrogen atoms bonded to a silicon atom per molecule.

[0098] [R 7 3SiO 1 / 2 ] a1 [H(R 7 )2SiO 1 / 2 ] b1 [SiO 4 / 2 ] c1

[0099] [R 8 OSiO 3 / 2 ] d1 (9)

[0100] In the formula, R 7 Same as above, R 8 is a hydrogen atom or an unsubstituted monovalent hydrocarbon group having 1 to 6 carbon atoms, a1 is 0 or a positive number, b1 is a positive number, c1 is a positive number, and d1 is 0 or a positive number. The upper limits of a1, b1, c1, and d1 are each a number satisfying 20.

[0101] A curable liquid silicone composition is prepared by mixing and dissolving a diorganopolysiloxane (B-1) having two or more alkenyl groups in one molecule, an organopolysiloxane resin (B-2) having alkenyl groups, and an organohydrogenpolysiloxane (B-3) having two or more SiH groups in one molecule.

[0102] The curable liquid silicone composition is a composition in which the component (B-2) is set to 1.0 to 65 parts by mass relative to the total amount of the component (B-1), the component (B-2) and the component (B-3) of 100 parts by mass. If the component (B-2) is less than 1.0 parts by mass, the elongation or strength of the silicone rubber decreases. If it is more than 65 parts by mass, the viscosity of the liquid silicone composition increases, and the emulsification described later becomes difficult. It is preferably 2.0 to 55 parts by mass, and more preferably 4.0 to 45 parts by mass.

[0103] The curable liquid silicone composition preferably has a composition in which the number ratio of SiH groups in component (B-3) is 0.9 to 3.0 relative to the total amount of alkenyl groups in component (B-1) and alkenyl groups in component (B-2). If the number ratio of SiH groups in component (B-3) is less than 0.9, the elongation or strength of the silicone rubber decreases. If it is higher than 3.0, the dispersed particles may aggregate in the aqueous dispersion of silicone rubber particles described later. More preferably, it is in the range of 1.0 to 2.3.

[0104] The silicone rubber of the silicone rubber particles is an addition reaction product of the curable liquid silicone composition. It is preferred to use a catalyst in the addition reaction. Examples of the catalyst for the addition reaction include platinum group metal catalysts used in hydrosilylation reactions. For example, the following can be cited: platinum group metal monomers such as platinum (including platinum black), rhodium, and palladium; platinum chloride, chloroplatinic acid, and chloroplatinates such as H2PtCl4·XH2O, H2PtCl6·XH2O, NaHPtCl6·XH2O, KHPtCl6·XH2O, Na2PtCl6·XH2O, K2PtCl4·XH2O, PtCl4·XH2O, PtCl2, and Na2HPtCl4·XH2O (wherein X is an integer from 0 to 6, preferably 0 or 6); alcohol-modified chloroplatinic acid; complexes of platinum chloride, chloroplatinic acid, and olefins; complexes of chloroplatinic acid and vinyl siloxane; complexes of platinum and vinyl siloxane; catalysts in which platinum group metals such as platinum black and palladium are loaded on carriers such as alumina, silica, and carbon; rhodium-olefin complexes; chlorotri(triphenylphosphine)rhodium (Wilkinson catalyst), etc. One type may be used alone, or two or more types may be used in combination.

[0105] The amount of the platinum group metal catalyst to be formulated is an effective amount as an addition reaction catalyst, and is an amount such that the amount of the platinum group metal in the platinum group metal catalyst relative to the total amount of the component (B-1), the component (B-2) and the component (B-3) is generally about 0.1 ppm to 500 ppm, preferably about 0.5 ppm to 200 ppm, and more preferably about 1 ppm to 100 ppm, calculated on a mass basis.

[0106] The curing conditions of the addition reaction of the curable liquid silicone composition are not particularly limited, but are preferably performed at a temperature of 1° C. to 100° C. for 1 hour or more. The temperature is preferably 10° C. to 100° C.

[0107] The silicone rubber of the silicone rubber particles preferably has an elongation at break of 15% or more and a tensile strength at break of 0.9 MPa or more. The elongation at break and the tensile strength at break refer to the values ​​measured by the test method specified in JIS K 6251:2017 for a dumbbell-shaped No. 3 test piece with a thickness of 1 mm that has been heat treated at 150°C for 30 minutes. If the elongation or tensile strength is low, the wear resistance of the obtained film deteriorates. More preferably, the elongation at break is 20% or more and the tensile strength at break is 1.0 MPa or more. The upper limit of the elongation at break is not particularly limited, as long as it is 1000% or less, especially 500% or less. The upper limit of the tensile strength at break is not particularly limited, as long as it is 20 MPa or less, especially 10 MPa or less.

[0108] The silicone rubber type A durometer hardness of the silicone rubber particles is preferably in the range of 20 to 95. The hardness refers to the value measured by the test method specified in JIS K 6253:2012 for a test piece heat-treated at 150°C for 30 minutes. If the hardness is low, the surface smoothness of the obtained film is low, and if the hardness is high, the wear resistance is deteriorated. It is more preferably in the range of 40 to 85.

[0109] Silicone rubber may also contain silicone oil, organic silane, inorganic powder, organic powder, antioxidant and the like.

[0110] The aqueous dispersion (B) of silicone rubber particles of the present invention is a composition containing, in addition to silicone rubber particles, a surfactant and water. The surfactant functions as a dispersant for silicone rubber particles. In addition, as described later, it also functions as an emulsifier for a curable liquid silicone composition in the production of the aqueous dispersion of silicone rubber particles.

[0111] The surfactant is not particularly limited and may be a nonionic surfactant, an anionic surfactant, a cationic surfactant or two ionic surfactants. A nonionic surfactant or an anionic surfactant is preferred. These may be used alone or in combination of two or more.

[0112] Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, glycerol fatty acid esters, polyoxyethylene glycerol fatty acid esters, polyglycerol fatty acid esters, propylene glycol fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene hydrogenated castor oil fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, polyoxyethylene modified organopolysiloxanes, and polyoxyethylene polyoxypropylene modified organopolysiloxanes.

[0113] Preferred are polyoxyethylene alkyl ethers or polyoxyethylene polyoxypropylene alkyl ethers having a hydrophilic-lipophilic balance (HLB) value of 12.0 to 19.0. More preferred are polyoxyethylene alkyl ethers or polyoxyethylene polyoxypropylene alkyl ethers having an alkyl group with a carbon number of 10 to 18. In addition, the HLB value is more preferably 13.0 to 18.0.

[0114] In addition, the HLB value here is a value calculated by Griffin's formula represented by the following formula.

[0115] HLB = [molecular weight of the polyoxyethylene part and the alcohol part / molecular weight of the surfactant] × 20

[0116] When two or more nonionic surfactants having different HLB values ​​are used in combination, the HLB value is a weighted average value.

[0117] Examples of the anionic surfactant include alkyl sulfate ester salts such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfate ester salts, polyoxyethylene alkylphenyl ether sulfate ester salts, sulfate ester salts of fatty acid alkylolamides, alkylbenzene sulfonates, polyoxyethylene alkylphenyl ether sulfonates, α-olefin sulfonates, α-sulfofatty acid ester salts, alkylnaphthalene sulfonates, alkyldiphenyl ether disulfonates, alkane sulfonates, N-acyltaurates, dialkyl sulfosuccinates, monoalkyl sulfosuccinates, polyoxyethylene alkyl ether sulfosuccinates, fatty acid salts, polyoxyethylene alkyl ether carboxylates, N-acylamino acid salts, monoalkyl phosphate ester salts, dialkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts, and the like.

[0118] Preferred are alkyl sulfates having an alkyl group with 10 to 18 carbon atoms, polyoxyethylene alkyl ether sulfates, sulfates of fatty acid alkylolamides, alkylbenzene sulfonates, α-sulfofatty acid esters, alkane sulfonates, N-acyltaurates, polyoxyethylene alkyl ether sulfosuccinates, polyoxyethylene alkyl ether carboxylates, N-acylamino acid salts, monoalkyl phosphates, dialkyl phosphates, polyoxyethylene alkyl ether phosphates, α-olefin sulfonates having an olefin with 10 to 18 carbon atoms, alkylnaphthalene sulfonates having an alkyl group with 1 to 14 carbon atoms, and alkyldiphenylether disulfonates having an alkyl group with 6 to 14 carbon atoms.

[0119] Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, polyoxyethylene alkyldimethylammonium salts, dimeroxyethylene alkylmethylammonium salts, trimeroxyethylene alkylammonium salts, alkylbenzyldimethylammonium salts, alkylpyridinium salts, monoalkylamine salts, and monoalkylamideamine salts.

[0120] Examples of the amphoteric surfactant include alkyl dimethyl amine oxide, alkyl dimethyl carboxy betaine, alkyl amidopropyl dimethyl carboxy betaine, alkyl hydroxysulfobetaine, and alkyl carboxymethyl hydroxyethyl imidazolinium betaine.

[0121] The amount of surfactant is 0.05 to 20 parts by mass relative to 100 parts by mass of silicone rubber particles. If it is less than 0.05 parts by mass, the emulsification of the curable liquid silicone composition described later cannot be performed, and the stability of the aqueous dispersion may decrease. Even if it is more than 20 parts by mass, the water dispersibility of the silicone rubber particles will not be improved, and the properties of the materials such as the prepared coating may be damaged. It is preferably 0.10 to 10 parts by mass, and more preferably 0.20 to 2 parts by mass.

[0122] The amount of water in the aqueous dispersion (B) of silicone rubber particles of the present invention is 20 to 2,000 parts by mass, preferably 40 to 1,000 parts by mass, based on 100 parts by mass of silicone rubber particles. The amount of silicone rubber particles based on the mass of the aqueous dispersion is preferably 5 to 70% by mass.

[0123] [Method for producing aqueous dispersion of silicone rubber particles (B)]

[0124] The aqueous dispersion (B) of silicone rubber particles can be produced by a known method. For example, the following method can be cited: a surfactant and water are added to a curable liquid silicone composition comprising component (B-1), component (B-2) and component (B-3), emulsified to form an emulsion, and then a platinum group metal catalyst is added to perform an addition reaction.

[0125] For emulsification, a general emulsifying and dispersing machine can be used, and examples thereof include: a high-speed rotating centrifugal radial agitator such as a homodisper; a high-speed rotating shearing agitator such as a homomixer; a high-pressure jet emulsifying and dispersing machine such as a homogenizer; a colloid mill; an ultrasonic emulsifying machine, etc. As long as emulsification can be achieved and the desired particle size can be formed, the stirring speed, time, etc. are not particularly limited.

[0126] After the emulsion is prepared, a platinum group metal catalyst is added. However, if the dispersibility in water is poor, it is preferably added to the emulsion in a state dissolved in a surfactant. Examples of the surfactant include the surfactants described above, and nonionic surfactants are particularly preferred. A method of pre-blending a platinum group metal catalyst in a curable liquid silicone composition is also possible, but in such a case, it is necessary to adjust the temperature, adjust the amount of the catalyst, or blend a reaction regulator, so that the reaction does not proceed until the emulsification is completed.

[0127] The addition reaction can be carried out at room temperature (1° C. to 30° C.), but in order to accelerate the reaction speed or increase the reaction rate, it can also be carried out under heating at less than 100° C. The addition reaction time is appropriately selected.

[0128] When silicone oil, organosilane, inorganic powder, organic powder, antioxidant, etc. are contained in the silicone rubber particles, these may be dissolved or dispersed in the curable liquid silicone composition.

[0129] In the present invention, the water dispersion of the silicone rubber particles or the silicone rubber particles are used in a coating agent. It is desirable that after the coating agent containing the silicone rubber particles is applied to the substrate, it is heat-treated at a temperature of 100°C to 300°C for 1 minute to 3 hours. By heat treatment, the addition reaction rate is improved, and the elongation and strength of the silicone rubber are increased. In addition, before the silicone rubber particles are mixed in a coating or a coating agent, they can be heat-treated at a temperature of 100°C to 300°C for 1 minute to 3 hours.

[0130] [Coating agent]

[0131] The coating agent of the present invention is a composition comprising the resin having film-forming property, the silicone rubber particles, and water. More specifically, it can be obtained by mixing an emulsion of the resin having film-forming property with an aqueous dispersion of the silicone rubber particles. The mixing can be performed using a conventionally known mixing and stirring machine including stirring blades of a paddle type, an anchor type, etc.

[0132] The mass ratio of the film-forming solid content in the (A) component to the silicone rubber particles in the (B) component is in the range of 85:15 to 25:75. If the ratio of the (B) component is small, the surface smoothness or wear resistance of the obtained film is low, and if the ratio of the (B) component is large, the wear resistance deteriorates. It is preferably 80:20 to 30:70. In addition, the amount of the (A) component in the coating agent is 0.5% to 59% by mass, preferably 1.2% to 50% by mass, and more preferably 2.5% to 42% by mass, based on the amount of resin. In addition, the amount of the (B) component in the coating agent is 0.3% to 52% by mass, preferably 0.7% to 44% by mass, and more preferably 1.5% to 37% by mass, based on the amount of silicone rubber.

[0133] In order to adjust the amount of components in the coating agent, water may be added. The coating agent of the present invention is aqueous, and the amount of water in the coating agent is 30% to 98% by mass, preferably 40% to 95% by mass, and more preferably 50% to 90% by mass. In the coating agent, various organic or inorganic pigments, wax emulsions, silicone oil emulsions, wettability enhancers, adhesion enhancers such as emulsions of chlorinated polyolefins, preservatives, tackifiers, pH adjusters, defoamers, etc. may be appropriately added as needed within the range that does not impair the effects of the present invention.

[0134] The coating agent of the present invention is suitable for coating on a substrate containing a rubber material. The rubber material is not particularly limited, and examples thereof include natural rubber, ethylene-propylene-diene monomer (EPDM), styrene butadiene rubber (SBR), chloroprene rubber, isoprene-isobutylene rubber, and nitrile rubber. The form of the substrate is not particularly limited, and may be any form such as a porous body or a hard body.

[0135] Examples of methods for applying the coating agent to the substrate include brushing, spraying, roller coating, flow coating, dip coating, and bar coating. The coating is preferably applied so that the thickness of the cured film is in the range of 1 μm to 40 μm, particularly 2 μm to 20 μm.

[0136] It is desirable to heat-treat the substrate at 100°C to 300°C after the coating agent is applied to the substrate. The resin component in the (A) component undergoes polymerization reaction or welding to form a high-strength film, and the addition reaction rate of the silicone rubber particles in the (B) component is increased, thereby increasing the hardness, elongation and strength of the silicone rubber. As a result, the surface smoothness and wear resistance are improved.

[0137] Example

[0138] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0139] In addition, in the examples, the dynamic viscosity is a value measured at 25°C using a capillary viscometer.

[0140] The following film-forming resin emulsion of the component (A) was prepared.

[0141] (A)-1: Adeka Bon-Tighter HUX-564

[0142] Urethane emulsion, solid content concentration = 40%, volume average particle size = 320nm, manufactured by ADEKA Co., Ltd.

[0143] (A)-2: Chaline RU-911

[0144] Urethane silicone emulsion, solid content concentration = 36%, volume average particle size = 260nm, manufactured by Nissin Chemical Industry Co., Ltd.

[0145] (A)-3: KM-9749

[0146] Silicone rubber emulsion, solid content concentration = 43%, volume average particle size = 190 nm, manufactured by Shin-Etsu Chemical Co., Ltd. The film properties of the component (A) were measured in the following manner.

[0147] The resin emulsion was poured into a polypropylene tray in an amount to give a thickness of about 1 mm after drying, and dried at 25° C. for 48 hours. The dried product was peeled off from the tray and heated in a hot air circulation thermostatic bath at 105° C. for 60 minutes to obtain a sheet.

[0148] The elongation at break and tensile strength at break of dumbbell-shaped No. 3 test pieces were tested according to the method specified in JIS K 6251: 2017. Six sheets were overlapped and the rubber hardness was measured using a type A durometer tester according to the method specified in JIS K 6251: 2017. The results are shown in Table 1.

[0149] [Table 1]

[0150]

[0151] [Production of Aqueous Dispersion of Silicone Rubber Particles as Component (B)]

[0152] The following polysiloxane was prepared.

[0153] (B-1)-1: represented by formula (10), vinyl content of 0.00627 mol / 100 g, dynamic viscosity of 5,060 mm 2 / s vinyl-containing dimethyl polysiloxane

[0154] [Chemistry 7]

[0155]

[0156] (B-1)-2: represented by formula (11), vinyl content of 0.00369 mol / 100 g, dynamic viscosity of 30,500 mm 2 / s vinyl-containing dimethyl polysiloxane

[0157] [Chemistry 8]

[0158]

[0159] (B-1)-3: represented by formula (12), vinyl content of 0.0179 mol / 100 g, dynamic viscosity of 386 mm 2 / s vinyl-containing dimethyl polysiloxane

[0160] [Chemistry 9]

[0161]

[0162] (B-1)-4: a dissolve of (A-1)-1 and (A-1)-3 in a mass ratio of 40:60, with a vinyl content of 0.0132 mol / 100 g and a dynamic viscosity of 1080 mm 2 / s vinyl-containing dimethyl polysiloxane

[0163] (B-1)-5: represented by formula (13), vinyl content of 0.0348 mol / 100 g, dynamic viscosity of 125 mm 2 / s vinyl-containing dimethyl polysiloxane

[0164] [Chemistry 10]

[0165]

[0166] (B-1)-6: represented by formula (14), vinyl content of 0.120 mol / 100 g, dynamic viscosity of 23 mm 2 / s vinyl-containing dimethyl polysiloxane

[0167] [Chemistry 11]

[0168]

[0169] (B-1)-7: represented by formula (15), vinyl content of 0.180 mol / 100 g, dynamic viscosity of 10 mm 2 / s vinyl-containing dimethyl polysiloxane

[0170] [Chemistry 12]

[0171]

[0172] (B-2)-1: Contains (CH3)3SiO 1 / 2 Unit, (CH3)2(CH=CH2)SiO 1 / 2 Unit, SiO 4 / 2 Unit, HOSiO 3 / 2 Unit, and CH3OSiO 3 / 2 units and a vinyl group-containing methyl polysiloxane resin having the following molar ratio.

[0173] Molar ratio ([(CH3)3SiO 1 / 2 ]+[(CH3)2(CH=CH2)SiO 1 / 2 ]) / [SiO 4 / 2 ] is 0.83;

[0174] Molar ratio [(CH3)3SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.71;

[0175] Molar ratio [(CH3)2(CH=CH2)SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.12;

[0176] Molar ratio ([HOSiO 3 / 2 ]+[CH3OSiO 3 / 2 ] / [SiO 4 / 2 ]) is 0.088;

[0177] Molar ratio [HOSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.041;

[0178] Molar ratio [CH3OSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.047,

[0179] The vinyl content was 0.089 mol / 100 g and the weight average molecular weight was 4,100.

[0180] (B-2)-2: Contains (CH3)3SiO 1 / 2 Unit, (CH=CH2)3SiO 1 / 2Unit, SiO 4 / 2 Unit, HOSiO 3 / 2 Unit, and C2H5OSiO 3 / 2 units and a vinyl group-containing methyl polysiloxane resin having the following molar ratio.

[0181] Molar ratio ([(CH3)3SiO 1 / 2 ]+[(CH=CH2)3SiO 1 / 2 ]) / [SiO 4 / 2 ] is 1.01;

[0182] Molar ratio [(CH3)3SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.90;

[0183] Molar ratio [(CH=CH2)3SiO 1 / 2 ] / [SiO 4 / 2 ] is 0.11;

[0184] Molar ratio ([HOSiO 3 / 2 ]+[C2H5OSiO 3 / 2 ] / [SiO 4 / 2 ]) is 0.10;

[0185] Molar ratio [HOSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.050;

[0186] Molar ratio [C2H5OSiO 3 / 2 ] / [SiO 4 / 2 ] is 0.050,

[0187] The vinyl content was 0.23 mol / 100 g and the weight average molecular weight was 5,730.

[0188] (B-3)-1: represented by formula (16), SiH group content is 0.418 mol / 100 g, dynamic viscosity is 27 mm 2 / s methyl hydrogen polysiloxane

[0189] [Chemistry 13]

[0190]

[0191] (B-3)-2: represented by formula (17), SiH group content is 0.744 mol / 100 g, dynamic viscosity is 117 mm 2 / s methyl hydrogen polysiloxane

[0192] [Chemistry 14]

[0193]

[0194] (B-3)-3: represented by formula (18), SiH group content is 0.137 mol / 100 g, dynamic viscosity is 37 mm 2 / s methyl hydrogen polysiloxane

[0195] [Chemistry 15]

[0196]

[0197] [Production of Component (B)-1]

[0198] A curable liquid silicone composition was prepared by mixing and dissolving a vinyl-containing dimethylpolysiloxane (B-1)-1, a vinyl-containing methylpolysiloxane resin (B-2)-1, and a methylhydrogenpolysiloxane (B-3)-1 at a mass ratio of 63.0:27.0:10.0. The ratio of the number of SiH groups in the methylhydrogenpolysiloxane to the total amount of the vinyl groups in the vinyl-containing dimethylpolysiloxane and the vinyl groups in the vinyl-containing methylpolysiloxane resin was 1.49.

[0199] 500.0 g of a curable liquid silicone composition, 2.0 g of polyoxyethylene tridecyl ether (ethylene oxide addition mole number = 15 mol) and 80.0 g of water were placed in a 1-liter glass beaker, and stirred at 6,000 rpm using a homogenizer. As a result, it became an oil-in-water type, and thickening was confirmed. Stirring was continued for 15 minutes. Next, 415.6 g of water was added while stirring at 2,000 rpm to obtain a uniform white emulsion. The emulsion was transferred to a 1-liter glass flask with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15°C to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. The mixture was stirred at the temperature for 6 hours to cure the curable liquid silicone by addition reaction, thereby obtaining an aqueous dispersion of silicone rubber particles (B)-1. The total amount of polyoxyethylene tridecyl ether and polyoxyethylene lauryl ether was 0.64 parts by mass relative to 100 parts by mass of the obtained silicone rubber particles.

[0200] The silicone rubber particles (B)-1 were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that it was 6.7 μm.

[0201] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic oven at 150°C for 30 minutes to volatilize and remove water, thereby further promoting the addition reaction. The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0202] The tensile strength at break and the elongation at break of the silicone rubber of the silicone rubber particles were measured as follows.

[0203] 0.24 parts by mass of an isododecane solution of a platinum-vinyl disiloxane complex (0.5% platinum content) and 0.05 parts by mass of 1,1-dimethylpropoxytrimethylsilane (reaction regulator) were mixed with 100 parts by mass of a curable liquid silicone composition prepared in the same composition as in Example 1, and poured into a polypropylene tray so as to have a thickness of about 1 mm. After being left at 25°C for 24 hours, the cured silicone was peeled off the tray and heated in a constant temperature bath at 150°C for 30 minutes to obtain a non-sticky silicone rubber sheet. The silicone rubber sheet was cut into the shape and size of a dumbbell No. 3 test piece specified in JIS K6251:2017, and the tensile strength at break and the elongation at break were measured according to the method specified in JIS K6251:2017. The tensile strength at break was 6.5 MPa, and the elongation at break was 101%.

[0204] The hardness of the silicone rubber of the silicone rubber particles was measured as follows.

[0205] 0.24 parts by mass of an isododecane solution of a platinum-vinyl disiloxane complex (0.5% platinum content) and 0.05 parts by mass of 1,1-dimethylpropoxytrimethylsilane (reaction regulator) were mixed with 100 parts by mass of a curable liquid silicone composition prepared with the same composition as in Example 1, and poured into an aluminum petri dish so as to have a thickness of 10 mm. After being left at 25°C for 24 hours, it was heated in a thermostatic bath at 150°C for 30 minutes to obtain a non-sticky silicone rubber. The hardness of the silicone rubber was measured using a type A durometer specified in JIS K6253, and the result was 58.

[0206] [Production of Component (B)-2 to Component (B)-12]

[0207] A water dispersion of silicone rubber particles was obtained in the same manner as in component (B)-1 except that a curable liquid silicone composition obtained by mixing and dissolving a vinyl-containing dimethylpolysiloxane, a vinyl-containing methylpolysiloxane resin, and a methylhydrogenpolysiloxane shown in Table 2 was used.

[0208] Table 2 shows the volume average particle size of the silicone rubber particles, the shape of the silicone rubber particles, the tensile strength at break of the silicone rubber, the elongation at break of the silicone rubber, and the hardness of the silicone rubber measured in the same manner as for component (B)-1.

[0209]

[0210] [Production of Component (B)-13]

[0211] A curable liquid silicone composition was prepared by mixing and dissolving a vinyl-containing dimethyl polysiloxane (B-1)-4, a vinyl-containing methyl polysiloxane resin (B-2)-1, and a methyl hydrogen polysiloxane (B-3)-1 at a mass ratio of 62.0:26.6:11.4. The composition was the same as that of the curable liquid silicone composition of the silicone rubber particles (B)-12. The tensile strength at break was 3.0 MPa, the elongation at break was 75%, and the hardness of the rubber measured by a type A durometer was 61.

[0212] 500.0 g of a curable liquid silicone composition, 1.0 g of polyoxyethylene tridecyl ether (ethylene oxide addition mole number = 15 mol) and 100.0 g of water were placed in a 1-liter glass beaker and stirred at 6,000 rpm using a homogenizer. As a result, the mixture became an oil-in-water type and thickening was confirmed. Stirring was continued for 15 minutes. Next, 396.6 g of water was added while stirring at 2,000 rpm to obtain a uniform white emulsion. The emulsion was transferred to a 1-liter glass flask equipped with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15°C to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. Stirring was performed at the temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.

[0213] The silicone rubber particles were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that the particle size distribution was 11 μm.

[0214] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic oven at 150°C for 30 minutes to volatilize and remove water, thereby further promoting the addition reaction. The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0215] [Production of Component (B)-14]

[0216] Into a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as that used in the manufacture of the silicone rubber particles (B)-13, 6.0 g of polyoxyethylene tridecyl ether (ethylene oxide addition mole number = 15 moles), and 40.0 g of water were placed, and stirred at 6,000 rpm using a homogenizer. As a result, it became an oil-in-water type, and thickening was confirmed. Next, the mixer was changed to a disperser and stirred at 4,000 rpm for 15 minutes. The mixer was changed to a homogenizer again, and 451.6 g of water was added while stirring at 2,000 rpm, resulting in a uniform white emulsion. The emulsion was transferred to a 1-liter glass flask equipped with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15° C. to 20° C., a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. Stirring was performed at the temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.

[0217] The silicone rubber particles were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that it was 1.9 μm.

[0218] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic oven at 150°C for 30 minutes to volatilize and remove water, thereby further promoting the addition reaction. The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0219] [Production of Component (B)-15]

[0220] Into a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as that used in the preparation of the silicone rubber particles (B)-13, 4.0 g of polyoxyethylene tridecyl ether (ethylene oxide addition mole number = 15 mol) and 80.0 g of water were placed, and stirred at 6,000 rpm using a homogenizer. As a result, it became an oil-in-water type, and thickening was confirmed. Stirring was continued for 15 minutes. Next, while stirring at 2,000 rpm, 413.6 g of water was added, and a uniform white emulsion was obtained. The emulsion was transferred to a 1-liter glass flask equipped with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15°C to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. The mixture was stirred at the above temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.

[0221] The silicone rubber particles were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that it was 4.5 μm.

[0222] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic oven at 150°C for 30 minutes to volatilize and remove water, thereby further promoting the addition reaction. The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0223] [Production of Component (B)-16]

[0224] Into a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as that used in the preparation of the silicone rubber particles (B)-13, 1.3 g of polyoxyethylene tridecyl ether (ethylene oxide addition mole number = 15 mol) and 80.0 g of water were placed, and stirred at 6,000 rpm using a homogenizer. As a result, it became an oil-in-water type, and thickening was confirmed. Stirring was continued for 15 minutes. Next, while stirring at 2,000 rpm, 416.3 g of water was added, and a uniform white emulsion was obtained. The emulsion was transferred to a 1-liter glass flask equipped with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15°C to 20°C, a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl-containing disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. The mixture was stirred at the above temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.

[0225] The silicone rubber particles were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that the particle size distribution was 8.7 μm.

[0226] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic oven at 150°C for 30 minutes to volatilize and remove water, thereby further promoting the addition reaction. The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0227] [Production of Component (B)-17]

[0228] Into a 1-liter glass beaker, 500.0 g of the same curable liquid silicone composition as that used in the manufacture of the silicone rubber particles (B)-13, 5.7 g of a 35% sodium pentylnaphthalenesulfonate aqueous solution (amount of sodium pentylnaphthalenesulfonate = about 2.0 g) and 76.0 g of water were placed, and stirred at 6,000 rpm using a homogenizer. As a result, the mixture became an oil-in-water type, and thickening was confirmed. Next, the mixer was changed to a disperser, and stirred at 4,000 rpm for 15 minutes. The mixer was changed to a homogenizer again, and 415.9 g of water was added while stirring at 2,000 rpm to obtain a uniform white emulsion. The emulsion was transferred to a 1-liter glass flask equipped with a stirring device using an anchor-type stirring blade, and after adjusting the temperature to 15° C. to 20° C., a mixed solution of 1.2 g of an isododecane solution of a platinum-vinyl disiloxane complex (platinum content 0.5%) and 1.2 g of polyoxyethylene lauryl ether (ethylene oxide addition mole number = 9 mol) was added under stirring. Stirring was performed at the temperature for 6 hours to obtain an aqueous dispersion of silicone rubber particles.

[0229] The silicone rubber particles were spherical when observed under an optical microscope, and the volume average particle size was measured using a particle size distribution measuring apparatus "Coulter Multisizer 3" (trade name, manufactured by Beckman Coulter Co., Ltd.) to find that the particle size distribution was 6.4 μm.

[0230] About 2 g of the obtained aqueous dispersion of silicone rubber particles was placed in an aluminum petri dish and heated in a hot air circulation thermostatic bath at 150° C. for 30 minutes to evaporate and remove water and further promote the addition reaction.

[0231] The obtained dried product was a non-sticky granular product, and its shape was spherical when observed under an electron microscope.

[0232] [Manufacturing of Silicone Rubber Particles for Comparative Example]

[0233] A water dispersion of silicone rubber particles was obtained in the same manner as component (B)-1 except that a curable liquid silicone composition prepared by mixing and dissolving a vinyl-containing dimethylpolysiloxane and a methylhydrogenpolysiloxane as shown in Table 3 was used. The volume average particle size of the silicone rubber particles, the shape of the silicone rubber particles, the tensile strength at break of the silicone rubber, the elongation at break of the silicone rubber, and the hardness of the silicone rubber measured in the same manner as component (B)-1 are shown in Table 3.

[0234] [Table 3]

[0235]

[0236] [Example 1 to Example 16, Comparative Example 1 to Comparative Example 4]

[0237] The (A) emulsion of the film-forming resin ((A)-1 or (A)-2), the (B) aqueous dispersion in which the addition reaction product of the curable liquid silicone composition, i.e., silicone rubber particles, is dispersed in an amount of 50% by mass, and water are mixed in the amounts shown in Tables 4, 5, and 6 to prepare a water-based coating agent. The obtained water-based coating agent is applied to one side of an EPDM rubber sheet (thickness 2 mm) using a brush, and heated in a hot air circulation thermostatic bath at 150°C for 5 minutes to form a hardened film. The hardened film is evaluated for surface smoothness and wear resistance according to the following evaluation method. The results are shown in Tables 4, 5, and 6.

[0238] [Surface smoothness test]

[0239] The dynamic friction coefficient against glass was measured using a friction and wear tester "Tribo Gear Type 40" (trade name, manufactured by Shinto Chemical Co., Ltd.). The glass plate was fixed to a workbench, and a 50 mm x 50 mm EPDM rubber sheet was attached to the indenter using double-sided tape. The dynamic friction coefficient was measured by reciprocating the indenter under the conditions of a load of 500 g, a moving speed of 1,000 mm / min, and a moving distance of 80 mm. The lower the dynamic friction coefficient, the higher the surface smoothness.

[0240] [Wear resistance test]

[0241] A wear test was conducted at a load of 300 g using a friction and wear tester "Tribo Gear Type 40" (trade name, manufactured by Shinto Chemical Co., Ltd.) using a stainless steel ball.

[0242] A 25mm×150mm EPDM rubber sheet was fixed on a workbench, and the pressure head was set to a stainless steel ball with a diameter of 10mm. It was reciprocated under the conditions of load: 300g, moving speed: 6,000mm / min, and moving distance: 50mm. Observation was performed at the reciprocating times of 1, 10, 50, 100, 500, 1000, 1500, and 2000, and the test was performed until the film peeling was observed. The results show the number of reciprocating times when the film peeling was observed.

[0243] [Table 4]

[0244]

[0245] [Table 5]

[0246]

[0247] [Table 6]

[0248]

[0249] ※(B)-18, (B)-19 and (B)-20 are compositions that do not contain component (B-2)

[0250] As shown in Tables 4 and 5, the coating agent of the present invention can form a coating film having excellent surface smoothness and abrasion resistance.

[0251] [Example 17 to Example 30, Comparative Example 5 to Comparative Example 8]

[0252] The emulsion of the film-forming resin ((A)-3) described above, the aqueous dispersion in which the addition reaction product of the curable liquid silicone composition (B) is dispersed in an amount of 50% by mass of silicone rubber particles, and water are mixed in the amounts shown in Tables 7, 8 and 9 to prepare an aqueous coating agent. The obtained aqueous coating agent is applied to one side of an EPDM rubber sheet (thickness 2 mm) using a brush, and heated in a hot air circulation thermostatic bath at 150°C for 5 minutes to form a hardened film. The surface smoothness and wear resistance of this hardened film are evaluated according to the following evaluation method. The results are shown in Tables 7, 8 and 9.

[0253] [Surface smoothness test]

[0254] The dynamic friction coefficient with respect to glass was measured using a friction and wear tester "Tribo Gear Type 40" (trade name, manufactured by Shinto Chemical Co., Ltd.).

[0255] Fix the glass plate on the workbench and attach a 50mm×50mm EPDM rubber sheet to the indenter with double-sided tape. Move it back and forth under the conditions of load: 500g, moving speed: 1,000mm / min, and moving distance: 80mm, and measure the dynamic friction coefficient at this time. The lower the dynamic friction coefficient, the higher the surface smoothness.

[0256] [Wear resistance test]

[0257] A wear test was conducted at a load of 1,000 g using a friction and wear tester "Tribo Gear Type 40" (trade name, manufactured by Shinto Chemical Co., Ltd.) using a stainless steel ball.

[0258] A 25mm×150mm EPDM rubber sheet was fixed on a workbench, and the pressure head was set to a stainless steel ball with a diameter of 10mm. It was reciprocated under the conditions of load: 1,000g, moving speed: 6,000mm / min, and moving distance: 50mm. Observation was performed at the reciprocating times of 100 times, 500 times, 1000 times, 1500 times, 2000 times, 2500 times, 3000 times, 3500 times, and 4000 times, and the test was performed until the film peeling was observed. The results show the number of reciprocating times when the film peeling was observed.

[0259]

[0260] [Table 8]

[0261]

[0262] [Table 9]

[0263]

[0264] ※(B)-20 is a composition that does not contain component (B-2)

[0265] As shown in Tables 7 and 8, the coating agent of the present invention can form a coating film having excellent surface smoothness and wear resistance even against high-load friction.

[0266] Industrial Applicability

[0267] The coating agent of the present invention can be used for the purpose of improving the sliding property, wear resistance and antifouling property of rubber rollers and preventing adhesion of O-rings, packings, gaskets, etc., and is particularly effective for improving the wear resistance, improving the sliding property and preventing squeaking of weather stripping rubber around car doors or trucks.

Claims

1. A coating agent comprising: (A) a resin having film-forming properties; (B) silicone rubber particles, which are an addition reaction product of a curable liquid silicone composition comprising the following components (B-1), (B-2) and (B-3); and water, (B-1) a diorganopolysiloxane having two or more alkenyl groups in one molecule; (B-2) an organopolysiloxane resin containing R 1 3SiO 1 / 2 Unit and SiO 4 / 2 Unit, R 1 3SiO 1 / 2 Unit relative to SiO 4 / 2 The molar ratio of the unit is 0.60 to 1.7, (In the formula, R 1 are independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 30 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and all R 1 at least one of which is alkenyl); and (B-3) organohydrogenpolysiloxane, having two or more silicon-bonded hydrogen atoms (called SiH groups) in one molecule, The amount of the component (B-2) is 1.0 to 65 parts by mass relative to 100 parts by mass of the total of the components (B-1), (B-2) and (B-3). In the coating agent, the mass ratio of the component (A) to the component (B) is 85:15 to 25:

75.

2. The coating agent according to claim 1, wherein the (B-1) diorganopolysiloxane has an alkenyl group content of 0.0025 mol / 100 g to 0.034 mol / 100 g, the (B-2) organopolysiloxane resin has an alkenyl group content of 0.001 mol / 100 g or more, and the (B-3) organohydrogenpolysiloxane has an SiH group content of 0.030 mol / 100 g to 1.30 mol / 100 g.

3. The coating agent according to claim 1, wherein the amount of (A) the film-forming resin is 0.5 to 59 parts by mass, the amount of (B) the silicone rubber particles is 0.3 to 52 parts by mass, and the amount of water is 30 to 98 parts by mass, relative to 100 parts by mass of the coating agent. 4 . The coating agent according to claim 1 , wherein the silicone rubber particles have a volume average particle diameter of 0.5 μm to 50 μm and are spherical. The coating agent according to claim 1 , comprising an emulsion of the resin having film-forming properties.

6. The coating agent according to claim 1, wherein the resin having film-forming properties is at least one selected from urethane resins, vinyl chloride resins, acrylic resins, silicone-acrylic copolymer resins, silicone-urethane copolymer resins, styrene-butadiene-acrylonitrile resins, polyester resins, amide resins, and silicone rubber. 7 . The coating agent according to claim 6 , wherein the film-forming resin is at least one selected from the group consisting of urethane resin, silicone rubber, and silicone-urethane copolymer resin. 8 . The coating agent according to claim 1 , wherein the aqueous dispersion containing the silicone rubber particles has an amount of 5% by mass to 70% by mass based on the mass of the aqueous dispersion.

9. The coating agent according to any one of claims 1 to 8, wherein the silicone rubber particles comprise a silicone rubber having an elongation at break of a dumbbell-shaped No. 3 test piece measured in accordance with Japanese Industrial Standard K6251:2017 of 15% or more for a rubber sheet having a thickness of 1 mm subjected to a heat treatment at 150° C. for 30 minutes, and a tensile strength at break measured in accordance with Japanese Industrial Standard K 6251:2017 of 0.9 MPa or more. 10 . The coating agent according to claim 1 , which is a coating agent for a rubber material.

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