Coating agents and resin components

Abstract

To provide a coating agent which enables formation of a coating film that is excellent in adhesion to a base material composed of a resin and has high durability to scratches by simple work, and a resin member having a coating film formed from the coating agent.SOLUTION: A coating agent contains a film formation component containing silsesquioxane having a Ta structural unit and a TC structural unit represented by the following composition formulae, and (meth)acrylate (excluding silsesquioxane), and a film curing component. The molar ratio of the content of the Ta structural unit to the total of the content of the Ta structural unit and the content of the Tc structural unit in the silsesquioxane exceeds 0 mol% and 45 mol% or less. The weight average molecular weight of the silsesquioxane is 2,000 or more. Ta structural unit: (R1SiO3 / 2). Tc structural unit: (R2SiO3 / 2). In the formulae, R1 is a (meth)acryloyl group, and R2 is a monovalent hydrocarbon group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to coating agents and resin components. [Background technology]

[0002] Traditionally, inorganic materials such as steel, aluminum, and glass have been used for components in vehicles such as automobiles and trains. In recent years, however, in order to reduce the weight of vehicles, there has been a trend to replace inorganic materials with organic materials such as plastics. However, while organic materials are lighter than inorganic materials, they are also softer and more easily scratched.

[0003] Therefore, in order to improve the scratch resistance of parts made of organic materials, a technique has been proposed to form a hard coating on the surface of the parts. For example, Patent Document 1 describes a coating member having a resin substrate, a primer layer formed on the surface of the resin substrate, and a hard coat layer formed on the primer layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-240294 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when forming a coating consisting of a two-layer structure of a primer layer and a hard coat layer, as in the coating member described in Patent Document 1, it is necessary to sequentially perform the following steps: applying a primer to a resin substrate, drying the primer to form a primer layer, applying a coating agent on the primer layer, and curing the coating agent to form a hard coat layer. As a result, the coating process becomes complicated and leads to increased costs associated with the coating process.

[0006] This invention has been made in view of the above background, and aims to provide a coating agent that can form a coating film with excellent adhesion to a resin substrate and high durability against scratches through simple work, and a resin member having a coating film formed from this coating agent. [Means for solving the problem]

[0007] One aspect of the present invention is a silsesquioxane comprising a Ta structural unit represented by the following compositional formula (1) and a Tc structural unit represented by the following compositional formula (2), A film-forming component comprising (meth)acrylate (excluding the silsesquioxane mentioned above), The film hardening component is configured to generate bases and radicals when irradiated with ultraviolet light, The molar ratio of the content of the Ta structural unit to the total content of the Tc structural unit in the silsesquioxane is greater than 0 mol% and less than or equal to 45 mol%, The coating agent is wherein the weight-average molecular weight of the silsesquioxane is 2,000 or more. (R 1 SiO 3 / 2 ) ···(1) (R 2 SiO 3 / 2 ) ···(2)

[0008] However, the above composition formula (1) It is derived from (meth)acryloxyalkyltrialkoxysilane. It is a structural unit, and the composition formula (2) This is a structural unit derived from alkyltrialkoxysilane. That is the case.

[0009] Another aspect of the present invention is a substrate made of resin, A resin member having a coating film formed on the substrate, The coating film is composed of a cured product of the coating agent according to the above embodiment. The coating film has a surface layer exposed on the surface of the resin member and an inner layer interposed between the surface layer and the base material, and the average concentration of Si atoms in the surface layer is higher than the average concentration of Si atoms in the inner layer, in the resin member.

Advantages of the Invention

[0010] The film-forming components in the coating agent include the specific silsesquioxane and (meth)acrylate. Further, the film-curing component in the coating agent is configured to be able to generate a base and radicals when irradiated with ultraviolet light. When such a coating agent is irradiated with ultraviolet light, a base and radicals are generated from the film-curing component. The base generated from the film-curing component can condense the silsesquioxane by a sol-gel reaction. Also, the radicals generated from the film-curing component can polymerize (meth)acrylate and silsesquioxane by radical polymerization.

[0011] Therefore, by irradiating the coating agent with ultraviolet light, the sol-gel reaction and radical polymerization can proceed in parallel. As a result, an inorganic component derived from silsesquioxane can be segregated on the surface of the coating film to improve the durability against scratches, and an organic component can be segregated in the vicinity of the base material in the coating film to improve the adhesion to the base material. Further, the coating agent can form a coating film having excellent adhesion to a base material made of resin and high durability against scratches by a simple operation of irradiating ultraviolet light after applying the coating agent to the base material.

[0012] As described above, according to the above aspect, it is possible to provide a coating agent capable of forming a coating film having excellent adhesion to a base material made of resin and high durability against scratches by a simple operation, and a resin member having a coating film formed from this coating agent.

Brief Description of the Drawings

[0013] [Figure 1] Figure 1 is a mapping image of Si atoms of a test piece produced using coating agent A1 in Experimental Example 1. [Figure 2] Figure 2 is a mapping image of Si atoms of a test piece produced using coating agent A2 in Experimental Example 1.

Mode for Carrying Out the Invention

[0014] (Coating Agent) The coating agent has a film-forming component that forms a coating film upon curing and a film-curing component for curing the film-forming component. Hereinafter, the constitution of each component contained in the coating material will be described.

[0015] 〔Film-Forming Component〕 The film-forming component contains silsesquioxane and (meth)acrylate.

[0016] · Silsesquioxane The silsesquioxane contained in the film-forming component has a Ta structural unit represented by the following compositional formula (1) and a Tc structural unit represented by the following compositional formula (2). (R 1 SiO 3 / 2 ) ···(1) (R 2 SiO 3 / 2 ) ···(2)

[0017] However, the above compositional formula (1) This is a structural unit derived from (meth)acryloxyalkyltrialkoxysilane. and the above compositional formula (2) This is a structural unit derived from alkyltrialkoxysilane. are as follows. R in the above compositional formula (2) 2 is It is a monovalent hydrocarbon group, More specifically, it may be a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, etc. From the viewpoint of more surely obtaining the above-described effects, R in the above compositional formula (2) 2It is preferably a monovalent saturated hydrocarbon group, more preferably a saturated hydrocarbon group having 18 or fewer carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0018] Some of the Si atoms in the silsesquioxane are bonded to hydroxyl groups (-OH) or alkoxy groups (-OR). Therefore, the silsesquioxane can condense with bases generated from the film-curing component, forming inorganic components in the coating film. Furthermore, the (meth)acryloyl groups in the silsesquioxane can polymerize together with the (meth)acryloyl groups in the (meth)acrylate by radicals generated from the film-curing component.

[0019] The molar ratio of the content of Ta structural units to the total content of Tc structural units in the silsesquioxane is greater than 0 mol% and less than or equal to 45 mol%. Furthermore, the weight-average molecular weight of the silsesquioxane is 2,000 or more. By setting the content of Ta structural units in the silsesquioxane within the specified range, and the weight-average molecular weight of the silsesquioxane within the specified range, inorganic components derived from silsesquioxane can be segregated on the surface of the cured coating film. As a result, a surface layer mainly composed of inorganic components can be formed on the surface of the coating film, and an inner layer mainly composed of organic components can be formed between the surface layer and the substrate. A coating film having such a two-layer structure exhibits excellent adhesion to the resin substrate and durability against scratches.

[0020] If the content of Ta structural units in silsesquioxane exceeds 45 mol% relative to the sum of the content of Ta structural units and Tc structural units, the inorganic components tend to be uniformly distributed throughout the cured coating film, which may lead to a decrease in scratch resistance. In this case, wrinkles are more likely to occur on the surface of the coating film, which may lead to deterioration of the appearance of the resin component on which the coating film is formed. To avoid these problems, the content of Ta structural units in silsesquioxane should be 45 mol% or less relative to the sum of the content of Ta structural units and Tc structural units.

[0021] The content of Ta structural units in silsesquioxane is preferably 5 mol% or more, more preferably 10 mol% or more, even more preferably 15 mol% or more, particularly preferably 20 mol% or more, and most preferably 25 mol% or more, relative to the sum of the content of Ta structural units and Tc structural units. In this case, the wear resistance of the coating film can be further improved.

[0022] In determining a preferred range for the content of Ta structural units in silsesquioxane, the aforementioned upper and lower limits for the content of Ta structural units can be arbitrarily combined. For example, the preferred range for the content of Ta structural units in silsesquioxane may be 5 mol% to 45 mol%, 10 mol% to 45 mol%, 15 mol% to 45 mol%, 20 mol% to 45 mol%, or 25 mol% to 45 mol% relative to the sum of the content of Ta structural units and Tc structural units.

[0023] If the weight-average molecular weight of silsesquioxane is less than 2,000, the inorganic components tend to be uniformly distributed throughout the coating film after curing, which may lead to a decrease in scratch resistance. In this case, the abrasion resistance of the coating film may also decrease. These problems can be easily avoided by setting the weight-average molecular weight of silsesquioxane to 2,000 or more, preferably 2,500 or more, more preferably 3,000 or more, even more preferably 3,500 or more, and particularly preferably 4,000 or more.

[0024] On the other hand, if the weight-average molecular weight of silsesquioxane becomes excessively large, the viscosity of the coating agent may increase excessively, potentially leading to a deterioration in workability during the application of the coating agent. From the viewpoint of avoiding such problems, the weight-average molecular weight of silsesquioxane is preferably 25,000 or less, more preferably 20,000 or less, even more preferably 15,000 or less, and particularly preferably 13,000 or less.

[0025] In determining the preferred range for the weight-average molecular weight of silsesquioxane, the aforementioned upper and lower limits for the weight-average molecular weight of silsesquioxane can be arbitrarily combined. For example, the preferred range for the weight-average molecular weight of silsesquioxane may be 2,000 to 25,000, 2,000 to 20,000, 2,500 to 15,000, 3,000 to 15,000, 4,000 to 15,000, or 4,000 to 13,000.

[0026] The silsesquioxane may further contain the Q structural unit represented by the following compositional formula (3). In this case, it is preferable that the molar ratio of the Q structural unit content to the sum of the Ta structural unit content, Tc structural unit content and Q structural unit content in the silsesquioxane is greater than 0 mol% and less than or equal to 25 mol%. (SiO 4 / 2 ) ···(3)

[0027] By introducing Q structural units into silsesquioxane, the wear resistance of the coating film can be further improved. From the viewpoint of improving the wear resistance of the coating film, the content of Q structural units in silsesquioxane is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 3 mol% or more, relative to the sum of the content of Ta structural units, Tc structural units, and Q structural units.

[0028] On the other hand, if the Q structural unit content in silsesquioxane is excessively high, aggregates of silsesquioxane are likely to form in the coating film, which may lead to deterioration of the coating film's appearance and a decrease in its abrasion resistance. These problems can be easily avoided by setting the Q structural unit content in silsesquioxane to preferably 25 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less, particularly preferably 10 mol% or less, and most preferably 8 mol% or less, relative to the sum of the Ta structural unit content, Tc structural unit content, and Q structural unit content.

[0029] In determining a preferred range for the Q structural unit content in silsesquioxane, the aforementioned upper and lower limits for the Q structural unit content can be arbitrarily combined. For example, the preferred range for the Q structural unit content in silsesquioxane may be 1 mol% to 20 mol%, 1 mol% to 15 mol%, 2 mol% to 10 mol%, 2 mol% to 8 mol%, or 3 mol% to 8 mol% relative to the sum of the Ta structural unit content, Tc structural unit content, and Q structural unit content.

[0030] The silsesquioxane content in the coating agent is preferably 30 to 150 parts by mass, more preferably 40 to 125 parts by mass, and even more preferably 50 to 100 parts by mass, per 100 parts by mass of (meth)acrylate. In this case, a better balance can be obtained between the hardness improvement effect of the inorganic component and the adhesion and flexibility improvement effects of the organic component.

[0031] The silsesquioxane used in the coating agent is obtained, for example, by condensing a plurality of alkoxysilanes, including a (meth)acryloxyalkyltrialkoxysilane that forms the Ta structural unit and an alkyltrialkoxysilane that forms the Tc structural unit.

[0032] Examples of (meth)acryloxyalkyltrialkoxysilanes that form the Ta structural unit include 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-methacryloxypropyltriethoxysilane. These (meth)acryloxyalkyltrialkoxysilanes may be used alone in the synthesis of silsesquioxane. Alternatively, silsesquioxane can be synthesized by using two or more (meth)acryloxyalkyltrialkoxysilanes in combination.

[0033] Examples of alkyltrialkoxysilanes that form the Tc structural unit include methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, isopropyltriethoxysilane, and n-butyltriethoxysilane. These alkyltrialkoxysilanes may be used alone in the synthesis of silsesquioxane. Alternatively, silsesquioxane can be synthesized by using two or more alkyltrialkoxysilanes in combination.

[0034] When introducing the Q structural unit into silsesquioxane, the synthesis of silsesquioxane can be carried out using tetraalkoxysilanes in addition to the trialkoxysilanes mentioned above. Examples of tetraalkoxysilanes that can serve as the Q structural unit include tetramethoxysilane and tetraethoxysilane. These tetraalkoxysilanes may be used alone in the synthesis of silsesquioxane. Alternatively, silsesquioxane can be synthesized by using two or more types of tetraalkoxysilanes in combination.

[0035] The reaction conditions for synthesizing silsesquioxane using alkoxysilane are not particularly limited; the alkoxysilane can be condensed using known methods.

[0036] (Meth)acrylate In this specification, (meth)acrylate refers to acrylic acid esters and methacrylic acid esters. However, silsesquioxane is excluded from the definition of (meth)acrylate. (Meth)acrylate contained in the film-forming component can undergo radical polymerization by radicals generated from the film-curing component, forming organic components in the coating film. In addition, (meth)acrylate can react with the (meth)acryloyl group contained in silsesquioxane and bond to the silsesquioxane.

[0037] By incorporating (meth)acrylate into the coating agent, an inner layer mainly composed of organic components can be formed in the coating film. As a result, the adhesion between the substrate and the coating film can be further improved.

[0038] The film-forming component may contain one type of (meth)acrylate selected from the group consisting of acrylates and methacrylates, or it may contain two or more types of (meth)acrylates. Examples of (meth)acrylates that can be included in the film-forming component include (meth)acrylic acid monoesters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, 1-methylethyl (meth)acrylate, butyl (meth)acrylate, 2-methylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate; (meth)acrylic acid diesters such as 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and isocyanurate ethylene oxide modified di(meth)acrylate; and (meth)acrylic acid esters having three or more (meth)acryloyl groups, such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and isocyanurate ethylene oxide modified tri(meth)acrylate. Furthermore, the (meth)acrylate may be a monomer of the compound described above, or it may be an oligomer obtained by polymerizing multiple monomers in advance.

[0039] It is preferable that the (meth)acrylate has three or more (meth)acryloyl groups per molecule. In this case, the structural units derived from (meth)acrylate and the structural units derived from silsesquioxane can be polymerized in a network-like manner. As a result, the hardness of the coating film can be increased and its resistance to scratches can be further improved. Furthermore, from the viewpoint of further improving weather resistance, it is preferable that the (meth)acrylate has an isocyanuric ring.

[0040] [Film curing component] The coating agent contains a film-curing component for promoting the curing reaction of the film-forming component. The film-curing component is configured to generate both a base and a radical when irradiated with ultraviolet light. For example, the film-curing component may contain a photobase generator configured to generate both a base and a radical when irradiated with ultraviolet light. Alternatively, the film-curing component may contain both a photobase generator configured to generate a base when irradiated with ultraviolet light and a photoradical polymerization initiator configured to generate a radical when irradiated with ultraviolet light.

[0041] • Photobase generator A photobase generator only needs to be configured to generate at least a base when irradiated with ultraviolet light. In other words, a compound that generates only a base when irradiated with ultraviolet light can be used as a photobase generator. Alternatively, a compound that generates both a base and a radical when irradiated with ultraviolet light can also be used as a photobase generator.

[0042] More specifically, as a photobase generator, a compound can be used that has an ultraviolet light absorbing portion in its molecular structure containing aromatic rings such as benzene rings, naphthalene rings, phenanthrene rings, anthracene rings, anthraquinone rings, xanthene rings, and thioxanthene rings, and a base portion that is bonded to the ultraviolet light absorbing portion and contains structural units that become bases when detached from the ultraviolet light absorbing portion, such as primary to tertiary amino groups, quaternary ammonium cations, carbamoyl groups, carbamate bonds, imino bonds, and nitrogen-containing heterocycles.

[0043] Examples of such compounds include 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium=n-butyltriphenyl borate, (Z)-{[bis(dimethylamino)methylidene]amino}-N-cyclohexyl(cyclohexylamino)methaneiminium=tetrakis(3-fluorophenyl) borate, 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidium=2-(3-benzoylphenyl)propionate, N,N-diethylcarbamate 9-anthrylmethyl, (E)-1-piperidino-3-(2-hydroxyphenyl)-2-propen-1-one, and imidazole-1-carboxylic acid 1 Examples include -(anthraquinone-2-yl)ethyl, 4-(methacryloyloxy)piperidine-1-carboxylic acid (2-nitrophenyl)methyl, cyclohexylcarbamate 1,2-bis(4-methoxyphenyl)-2-oxoethyl, cyclohexylcarbamate 2-nitrobenzyl, 2-(9-oxoxanthene-2-yl)propionic acid 1,5,7-triazabicyclo[4.4.0]deca-5-ene, 2-(9-oxoxanthene-2-yl)propionic acid 1,5-diazabicyclo[4.3.0]nona-5-ene, 2-(9-oxoxanthene-2-yl)propionic acid 1,8-diazabicyclo[5.4.0]undeca-7-ene, acetophenone O-benzoyloxime, 2-(piperidine-1-carbonyl)benzaldehyde, nifedipine, etc. The photobase generator is preferably one or more compounds selected from the group consisting of 1,2-bis(4-methoxyphenyl)-2-oxoethyl cyclohexylcarbamate, 2-nitrobenzyl cyclohexylcarbamate, 1,5,7-triazabicyclo[4.4.0]deca-5-ene 2-(9-oxoxanthene-2-yl)propionic acid, 1,5-diazabicyclo[4.3.0]nona-5-ene 2-(9-oxoxanthene-2-yl)propionic acid, and 1,8-diazabicyclo[5.4.0]undeca-7-ene 2-(9-oxoxanthene-2-yl)propionic acid.

[0044] • Initiator of photoradical polymerization The film-curing component may contain a photoradical polymerization initiator. The photoradical polymerization initiator is configured to generate radicals when the coating agent is irradiated with ultraviolet light. By incorporating a photoradical polymerization initiator into the coating agent, radical polymerization of the film-forming component can be promoted, and organic components can be formed in the coating film.

[0045] Examples of photoradical polymerization initiators that can be used include acetophenone compounds, benzophenone compounds, α-ketoester compounds, phosphine oxide compounds, benzoin compounds, titanocene compounds, acetophenone / benzophenone hybrid photoinitiators, oxime ester photoinitiators, and camphorquinone.

[0046] Examples of acetophenone compounds include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, diethoxyacetophenone, oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone} and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one.

[0047] Examples of benzophenone compounds include benzophenone, 4-phenylbenzophenone, 2,4,6-trimethylbenzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Examples of α-ketoester compounds include methylbenzoyl formate, 2-(2-oxo-2-phenylacetoxyethoxy)ethyl ester of oxyphenylacetic acid, and 2-(2-hydroxyethoxy)ethyl ester of oxyphenylacetic acid.

[0048] Examples of phosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Examples of benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether. Examples of acetophenone / benzophenone hybrid photoinitiators include 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfinyl)propan-1-one. Examples of oxime ester photopolymerization initiators include 2-(O-benzoyloxime)-1-[4-(phenylthio)]-1,2-octanedione.

[0049] As a photoradical polymerization initiator, one compound selected from these compounds may be used, or two or more compounds may be used in combination.

[0050] The amount of film-hardening component in the coating agent, the ratio of photobase generator to photoradical polymerization initiator, etc., can be appropriately set according to the composition of the film-hardening component. For example, the amount of film-hardening component in the coating agent can be appropriately set from a range of 0.1 parts by mass to 10 parts by mass per 100 parts by mass of film-forming component.

[0051] [Other additives] In addition to film-forming and film-hardening components, the coating agent may also contain additives known for use in coating agents, to the extent that they do not impair the hardening of the coating agent. For example, the coating agent may contain additives such as ultraviolet absorbers, radical scavengers, and hindered amine-based light stabilizers to suppress the degradation of the coating film. By using these additives, it is possible to expect an improvement in the weather resistance of the coating film.

[0052] Furthermore, the coating agent may contain surface modifiers such as leveling agents and defoaming agents as additives. By using these additives, the thickness of the coating agent can be made uniform when applied to the substrate. As a result, it is possible to further improve the scratch resistance of the resin component with the coating film.

[0053] (Resin component) A resin member can be obtained by applying the coating agent onto a resin substrate and then curing it. The resin member obtained in this way is A base material made of resin, It has a coating film formed on the substrate, The coating film is composed of a cured product of the coating agent. Furthermore, the coating film comprises a surface layer exposed on the surface of the resin member, It has an inner layer interposed between the surface layer and the substrate, The average concentration of Si atoms in the surface layer is higher than the average concentration of Si atoms in the inner layer.

[0054] Since the coating film is composed of a cured product of the coating agent, it has a surface layer mainly derived from silsesquioxane and an inner layer mainly derived from (meth)acrylate. Therefore, the resin member has excellent durability against scratches. Furthermore, the coating film also has excellent adhesion to the substrate.

[0055] Since the coating film formed by curing the coating agent is transparent, for example, by applying the coating agent to the surface of a transparent window component, i.e., a component that replaces window glass made of inorganic material, a transparent window component that is lighter than glass made of inorganic material can be obtained.

[0056] Furthermore, for example, by applying the coating agent to the surface of a body panel, a clear coat layer can be formed on the surface of the body panel. In addition, if necessary, a coloring agent such as a pigment can be added to the coating agent to color the coating film.

[0057] In the aforementioned resin component, the resin constituting the base material can be appropriately selected according to the application of the resin component. For example, when the resin component is used as a transparent window component, polycarbonate resin can be used as the base material. Polycarbonate resin has excellent properties required for transparent window components, such as weather resistance, strength, and transparency. Therefore, by forming the transparent coating film on a base material made of polycarbonate resin, a resin component suitable for use as a transparent window component can be obtained.

[0058] The resin member comprises, for example, a preparation step of preparing a base material made of resin, A coating step of applying the coating agent onto the surface of the substrate, A curing step in which a coating film consisting of a cured product of the coating agent is formed on the surface of the substrate by irradiating the coating agent with ultraviolet light, It can be manufactured by a manufacturing method having [a certain characteristic].

[0059] In the above-described manufacturing method, for applying the coating agent in the coating step, an appropriate device can be selected and used from among known coating devices such as spray coaters, flow coaters, spin coaters, dip coaters, bar coaters, and applicators, depending on the desired film thickness, the shape of the equipment, etc.

[0060] After the application process, a step of heating and drying the coating agent may be performed as needed.

[0061] For the irradiation of ultraviolet light during the curing process, an appropriate light source can be selected and used from among known light sources capable of generating ultraviolet light, such as mercury lamps, metal halide lamps, light-emitting diodes, and excimer lamps, depending on the absorption wavelength of the film curing component and the required amount of light. Furthermore, during the curing process, ultraviolet light may be irradiated in an atmospheric environment or in a nitrogen atmosphere. If necessary, the coating agent may be heated to accelerate the reaction while irradiating with ultraviolet light.

[0062] Furthermore, after the curing process, a step may be performed to heat the coating film to accelerate curing, if necessary. [Examples]

[0063] An example of the coating agent described above will now be explained. The coating agent in this example contains a film-forming component comprising a silsesquioxane having a Ta structural unit represented by the following compositional formula (1) and a Tc structural unit represented by the following compositional formula (2), and a (meth)acrylate (excluding the silsesquioxane), and a film-curing component configured to generate bases and radicals when irradiated with ultraviolet light. Furthermore, the molar ratio of the content of Ta structural units to the total content of Tc structural units in the silsesquioxane is greater than 0 mol% and less than or equal to 45 mol%, and the weight-average molecular weight of the silsesquioxane is 2,000 or more. (R 1 SiO 3 / 2 ) ···(1) (R 2 SiO 3 / 2 ) ···(2)

[0064] However, the above composition formula (1) This is a structural unit derived from (meth)acryloxyalkyltrialkoxysilane. The composition formula (2) This is a structural unit derived from alkyltrialkoxysilane. That is the case.

[0065] The silsesquioxane used in this example is as follows:

[0066] • Silsesquioxane Silsesquioxanes A1 to A12, shown in Tables 1 and 2, were synthesized by condensing several types of alkoxysilanes, including alkyltrialkoxysilanes and (meth)acryloxyalkyltrialkoxysilanes, using known methods. Specifically, the (meth)acryloxyalkyltrialkoxysilane used in this example is either methacryloxypropyltriethoxysilane (MAcSi(OEt)3) or methacryloxypropyltrimethoxysilane (MAcSi(OMe)3). Specifically, the alkyltrialkoxysilane used in this example is methyltriethoxysilane (MeSi(OEt)3). Specifically, the tetraalkoxysilane used in this example is tetraethoxysilane (Si(OEt)4).

[0067] (Meth)acryloxyalkyltrialkoxysilanes serve as the Ta structural units in silsesquioxane. Therefore, the "Ta structural units" column in Tables 1 and 2 shows the molar ratio of (meth)acryloxyalkyltrialkoxysilane used in the synthesis of silsesquioxane. Similarly, the "Tc structural units" column in Tables 1 and 2 shows the molar ratio of alkyltrialkoxysilanes that serve as Tc structural units in silsesquioxane, and the "Q structural units" column shows the molar ratio of tetraalkoxysilanes that serve as Q structural units in silsesquioxane. In addition, the "Ta / (Ta+Tc)" column in Table 1 shows the molar ratio of the Ta structural unit content to the sum of the Ta structural unit content and the Tc structural unit content, and the "Q / (Ta+Tc+Q)" column shows the molar ratio of the Q structural unit content to the sum of the Ta structural unit content, the Tc structural unit content and the Q structural unit content.

[0068] Furthermore, the "Weight-Average Molecular Weight" column in Tables 1 and 2 shows the weight-average molecular weight in polyethylene terms, obtained by gel permeation chromatography.

[0069] [Table 1]

[0070] [Table 2]

[0071] (Experimental Example 1) In this example, three types of coating agents (coating agents B1 to B3) shown in Table 3 were prepared using silsesquioxanes with different weight-average molecular weights. The coating agents in this example consist of a film-forming component containing 100 parts by mass of (meth)acrylate and 75 parts by mass of silsesquioxane, a film-curing component containing 3 parts by mass of a photobase generator, and a solvent for dissolving the film-forming component and the film-curing component.

[0072] The (meth)acrylate used in this example is specifically a mixture containing isocyanurate ethylene oxide modified triacrylate (M-315, manufactured by Toagosei Co., Ltd.). The silsesquioxane used in this example is one of silsesquioxanes A1 to A3, as shown in Table 3. The photobase generator used in this example is 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidium=2-(3-benzoylphenyl)propionate.

[0073] In this example, coating agents B1 to B3 shown in Table 3 were prepared by dissolving the aforementioned compounds in a solvent.

[0074] Next, a 5mm thick substrate made of polycarbonate resin was prepared, and one of the coating agents B1 to B3 was applied to the surface of the substrate using a bar coater. After applying the coating agent to the substrate, the substrate was pre-baked by heating it for 3 minutes in a hot air drying oven set to 100°C.

[0075] After pre-baking, a curing process was carried out in which the coating agent was irradiated with ultraviolet light to form a coating film consisting of cured coating material on the surface of the substrate. In this example, the ultraviolet light irradiation was performed in a nitrogen atmosphere. A high-pressure mercury lamp was used as the ultraviolet light source. The illuminance of the ultraviolet light was 250 mW / cm². 2 The exposure dose was 2500 mJ / cm². 2 That's what I decided.

[0076] After irradiation with ultraviolet light, the coating film was post-baked by heating it for 10 minutes in a hot air drying oven set to 130°C. Test pieces were obtained as a result. The obtained test pieces were colorless and transparent. The thickness of the coating film formed on the substrate was approximately 50 μm.

[0077] Using the test pieces obtained as described above, the layer structure, appearance, and abrasion resistance of the coating film were evaluated.

[0078] [Layer structure of the coating film] After exposing the cross-section of the test piece, a mapping image of Si atoms in the cross-section was obtained using scanning secondary electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX). Based on the Si atom mapping image, it was determined whether the layer structure of the coating film was a layer-separated structure with a surface layer and an inner layer, or a single-layer structure consisting of a single layer. As an example, Figure 1 shows a cross-section of test piece 1a prepared using coating agent B1. Figure 2 shows a cross-section of test piece 1b prepared using coating agent B2. In Figures 1 and 2, the brightly lit areas indicate areas with a high concentration of Si atoms.

[0079] As shown in Figure 1, the coating film 2a, which is made of the cured product of coating agent B1, has a surface layer 21 that is exposed on the surface 10 of the test piece 1a and appears relatively bright, and an inner layer 22 that is interposed between the surface layer 21 and the substrate 3 and appears darker than the surface layer 21. According to Figure 1, it can be seen that the surface layer 21 and the inner layer 22 are clearly separated in the coating film 2a. Furthermore, the surface layer 21 appears brighter than the inner layer 22, and the average concentration of Si atoms in the surface layer 21 is higher than the average concentration of Si atoms in the inner layer. From these results, it can be seen that the coating film 2a, which is made of the cured product of coating agent B1, has a layered structure consisting of two layers: the surface layer 21 and the inner layer 22.

[0080] On the other hand, as shown in Figure 2, the coating film 2b, which is made from the cured product of coating agent B2, consists of a single layer. Furthermore, according to Figure 2, the entire surface from the boundary with the substrate 3 to the surface 10 is displayed with uniform brightness, and it can be understood that Si atoms are distributed throughout the coating film 2b. From these results, it can be understood that the coating film made from the cured product of coating agent B1 consists of a single layer.

[0081] The layer structure determined based on the mapping images of Si atoms is shown in the "Layer Structure" column of Table 3.

[0082] 〔exterior〕 The appearance of the coating film was evaluated visually. If the coating film was transparent and its surface was smooth, "Good" was written in the "Appearance" column of Table 3. If the coating film was opaque or had irregularities such as wrinkles on its surface, "Poor" was written.

[0083] [Abrasion resistance] Abrasion testing of the coating film was performed using a Taber abrasion tester, and the abrasion resistance was evaluated based on the increase in haze value ΔH (unit: %) after the abrasion test. More specifically, after measuring the haze value of the test piece before the abrasion test, the test piece was mounted on the Taber abrasion tester. The abrasion test was then performed by abrading the coating film of the test piece with an abrasion wheel. In this example, the abrasion wheel of the Taber abrasion tester was CS-10F. The load in the abrasion test was 500gf, and the number of rotations was 1000.

[0084] After conducting abrasion tests under the aforementioned conditions, the haze value of the test pieces after the test was measured using a haze meter. The increase in haze value was then calculated by subtracting the haze value of the test piece before the test from the haze value of the test piece after the test. The "Abrasion Resistance" column in Table 3 shows the increase in haze value ΔH (unit: %) for the coating film obtained using each coating agent.

[0085] [Table 3]

[0086] The film-forming components of coating agents B1 and B3 contain (meth)acrylate and silsesquioxane. Furthermore, as shown in Table 3, the weight-average molecular weight of the silsesquioxane used in these coating agents, and the molar ratio of the Ta structural unit content to the sum of the Ta and Tc structural unit content, are all within the specified range. Therefore, the coating films formed using coating agents B1 and B3 have a two-layer structure consisting of a surface layer and an inner layer, and exhibit excellent scratch resistance. In addition, the coating films formed using these coating agents have a good appearance and excellent abrasion resistance.

[0087] On the other hand, coating agent B2 uses silsesquioxane A2, which has a weight-average molecular weight smaller than the aforementioned specific range. Therefore, the coating film formed using coating agent B2 consists of a single layer in which inorganic components are uniformly distributed, and has poor durability against scratches.

[0088] (Experimental Example 2) In this example, four types of coating agents (coating agents C1 to C4) were prepared using silsesquioxanes with different Ta structural unit contents, as shown in Table 4. The specific composition of coating agents C1 to C4 is the same as that of the coating agents in Experimental Example 1, except that one of the silsesquioxanes A4 to A7 was used in the preparation of the coating agents, and that an additional 2 parts by mass of photoradical polymerization initiator was included in the film curing component, as shown in Table 4. The photoradical polymerization initiators used in this example were Omnirad819 and Omnirad754 (both manufactured by IGM Resins BV). "Omnirad" is a registered trademark of IGM Group BV.

[0089] Using the coating agent prepared in this manner, the layer structure, appearance, and abrasion resistance of the coating film were evaluated using the same method as in Experimental Example 1. The results are shown in Table 4. Note that the coating agent in this example differs from the coating agent in Experimental Example 1 in that it contains a photoradical polymerization initiator in the film curing component. Furthermore, the value of the increase in haze value ΔH obtained from the abrasion test is greatly influenced by the condition of the abrasion wheel used in the abrasion test. The condition of the abrasion wheel used in the abrasion test in this example is different from the condition of the abrasion wheel used in the abrasion test in Experimental Example 1. For these reasons, the value of the increase in haze value ΔH obtained in this example cannot be directly compared with the value of ΔH obtained in Experimental Example 1.

[0090] [Table 4]

[0091] As shown in Table 4, the weight-average molecular weight of silsesquioxane used in coating agents C3 and C4, and the molar ratio of the content of Ta structural units to the total content of Tc structural units are all within the specified range. Therefore, the coating films formed using coating agents C3 and C4 have a two-layer structure consisting of a surface layer and an inner layer, and exhibit excellent scratch resistance. Furthermore, the coating films formed using these coating agents have a good appearance. Among these coating agents, coating agent C3, due to its moderately high content of Ta structural units, was able to further improve the abrasion resistance of the coating film compared to coating agent C4.

[0092] On the other hand, coating agents C1 and C2 use silsesquioxane with an excessively high content of Ta structural units. As a result, the coating films formed using these coating agents consist of a single layer with uniformly distributed inorganic components, resulting in poor scratch resistance. Furthermore, the coating films formed using these coating agents developed wrinkles on the surface, resulting in a poor appearance. In addition, because the coating films formed using coating agents C1 and C2 developed wrinkles on the surface, it was not possible to compare the increase in haze value ΔH after the abrasion test with ΔH in coating films with a smooth surface. Therefore, "Unable to evaluate" was written in the "Abrasion Resistance" column for coating agents C1 and C2.

[0093] (Experimental Example 3) In this example, three types of coating agents (coating agents D1 to D3) were prepared using silsesquioxanes with different Q structural unit content, as shown in Table 5. The specific composition of coating agents D1 to D3 is the same as that of the coating agent in Experimental Example 1, except that one of silsesquioxanes A3, A8, or A11 was used in the preparation of the coating agent, as shown in Table 5.

[0094] Using the coating agent prepared in this manner, the layer structure, appearance, and abrasion resistance of the coating film were evaluated using the same method as in Experimental Example 1. The results are shown in Table 5. For the same reasons as in Experimental Example 2, the increase in haze value ΔH obtained in this example cannot be directly compared with the ΔH values ​​obtained in other experimental examples.

[0095] [Table 5]

[0096] As shown in Table 5, the weight-average molecular weight of silsesquioxane used in coating agents D1 and D3, and the molar ratio of the content of Ta structural units to the total content of Tc structural units are all within the specified range. Therefore, the coating films formed using coating agents D1 and D3 have a two-layer structure consisting of a surface layer and an inner layer, and exhibit excellent scratch resistance. Furthermore, the coating films formed using these coating agents have a good appearance. Among these coating agents, coating agent D3, because its Q structural unit content is within the specified range, was able to further improve the abrasion resistance of the coating film compared to coating agent D1, which does not contain Q structural units.

[0097] On the other hand, coating agent D2 uses silsesquioxane A8, which has an excessively high content of Q structural units. As a result, aggregates of inorganic components formed in the coating film formed using coating agent D2, giving it an opaque appearance. Furthermore, because aggregates of inorganic components formed in the coating film formed using coating agent D2, the increase in haze value ΔH of the coating film formed using coating agent D2 cannot be compared with the increase in haze value ΔH of a coating film with a smooth surface. Therefore, "Unable to evaluate" was written in the "Abrasion Resistance" column for coating agent D2.

[0098] (Experimental Example 4) In this example, four types of coating agents (coating agents E1 to E4) were prepared using silsesquioxanes that contain Q structural units and have different Ta structural unit content, as shown in Table 6. The specific composition of coating agents E1 to E4 is the same as that of the coating agents in Experimental Example 2, except that one of the silsesquioxanes A9 to A12 was used to prepare the coating agents, as shown in Table 6.

[0099] Using the coating agent prepared in this manner, the layer structure, appearance, and abrasion resistance of the coating film were evaluated using the same method as in Experimental Example 1. The results are shown in Table 6. For the same reasons as in Experimental Example 2, the increase in haze value ΔH obtained in this example cannot be directly compared with the ΔH values ​​obtained in other experimental examples.

[0100] [Table 6]

[0101] As shown in Table 6, the weight-average molecular weight of silsesquioxane used in coating agents E2 to E4, and the molar ratio of the content of Ta structural units to the total content of Tc structural units, are all within the specified range. Therefore, the coating films formed using coating agents E2 to E4 have a two-layer structure consisting of a surface layer and an inner layer, and exhibit excellent scratch resistance. Furthermore, the coating films formed using these coating agents have a good appearance. Among these coating agents, coating agents E2 and E3, having a moderately high content of Ta structural units, were able to further improve the abrasion resistance of the coating film compared to coating agent E4, which has a low content of Ta structural units.

[0102] On the other hand, coating agent E1 uses silsesquioxane with an excessively high content of Ta structural units. As a result, the coating film formed using coating agent E1 consists of a single layer and has poor scratch resistance. In addition, the coating film formed using coating agent E1 developed wrinkles on its surface, resulting in a poor appearance. Furthermore, because the coating film formed using coating agent E1 developed wrinkles on its surface, it was not possible to compare the increase in haze value ΔH after the abrasion test with ΔH in a coating film with a smooth surface. Therefore, "Unable to evaluate" was written in the "Abrasion Resistance" column for coating agent E1.

[0103] The embodiments of the coating agent and resin component according to the present invention have been described above based on Experimental Examples 1 to 4. However, the specific embodiments of the coating agent and resin component according to the present invention are not limited to those of the experimental examples, and the configuration can be modified as appropriate without impairing the spirit of the present invention.

[0104] For example, the coating agent according to the present invention may take the following embodiments as shown in [1] to [8].

[0105] [1] A silsesquioxane comprising a Ta structural unit represented by the following compositional formula (1) and a Tc structural unit represented by the following compositional formula (2), A film-forming component comprising (meth)acrylate (excluding the silsesquioxane mentioned above), The film hardening component is configured to generate bases and radicals when irradiated with ultraviolet light, The molar ratio of the content of the Ta structural unit to the total content of the Tc structural unit in the silsesquioxane is greater than 0 mol% and less than or equal to 45 mol%, A coating agent wherein the weight-average molecular weight of the silsesquioxane is 2,000 or more. (R 1 SiO 3 / 2 ) ···(1) (R 2 SiO 3 / 2 ) ···(2) (However, R in the above composition formula (1) 1 R is an acryloyl group or a methacryloyl group, and R in the above composition formula (2) 2 (This is a monovalent hydrocarbon group.)

[0106] [2] The coating agent according to [1], wherein the molar ratio of the content of the Ta structural unit to the sum of the content of the Ta structural unit and the content of the Tc structural unit in the silsesquioxane is 20 mol% or more and 45 mol% or less. [3] The coating agent according to [1] or [2], wherein the weight-average molecular weight of the silsesquioxane is 2,000 or more and 15,000 or less.

[0107] [4] The coating agent according to any one of [1] to [3], wherein the silsesquioxane further contains a Q structural unit represented by the following composition formula (3), and the molar ratio of the content of the Q structural unit to the sum of the content of the Ta structural unit, the Tc structural unit, and the Q structural unit in the silsesquioxane is greater than 0 mol% and less than or equal to 25 mol%. (SiO 4 / 2 ) ···(3) [5] The coating agent according to any one of [1] to [4], wherein the content of the silsesquioxane is 30 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the (meth)acrylate.

[0108] [6] The coating agent according to any one of [1] to [5], wherein the film curing component includes a photobase generator configured to generate both bases and radicals when irradiated with ultraviolet light. [7] The coating agent according to any one of [1] to [5], wherein the film curing component comprises a photobase generator configured to generate a base when irradiated with ultraviolet light, and a photoradical polymerization initiator configured to generate radicals when irradiated with ultraviolet light. [8] The coating agent according to any one of [1] to [7], wherein the (meth)acrylate has an isocyanuric ring.

[0109] Furthermore, the resin member according to the present invention may take the form shown in [9] below.

[0110] [9] A base material made of resin, A resin member having a coating film formed on the substrate, The coating film is composed of a cured product of the coating agent described in any one of [1] to [8], The coating film comprises a surface layer exposed on the surface of the resin member, It has an inner layer interposed between the surface layer and the substrate, A resin member wherein the average concentration of Si atoms in the surface layer is higher than the average concentration of Si atoms in the inner layer. [Explanation of symbols]

[0111] 1a Test piece 2a Coating film 21 Surface layer 22 Inner layer 3 Base material

Claims

1. A coating agent for forming a coating film on the surface of a resin substrate, Silsesquioxane and, A film-forming component comprising (meth)acrylate (excluding the silsesquioxane mentioned above), The film hardening component is configured to generate bases and radicals when irradiated with ultraviolet light, The silsesquioxane is a silsesquioxane comprising a Ta structural unit derived from (meth)acryloxyalkyltrialkoxysilane and a Tc structural unit derived from alkyltrialkoxysilane, or a silsesquioxane comprising the Ta structural unit, the Tc structural unit, and a Q structural unit represented by the following compositional formula (3), wherein the molar ratio of the Q structural unit content to the sum of the content of the Ta structural unit, the Tc structural unit, and the Q structural unit content is greater than 0 mol% and less than or equal to 25 mol%, The molar ratio of the content of the Ta structural unit to the total content of the Tc structural unit in the silsesquioxane is greater than 0 mol% and less than or equal to 45 mol%, The weight-average molecular weight of the silsesquioxane is 2,000 or more. The silsesquioxane content is 30 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the (meth)acrylate. A coating agent wherein the film curing component comprises (i) a photobase generator configured to generate both a base and a radical when irradiated with ultraviolet light, or (ii) a photobase generator configured to generate a base when irradiated with ultraviolet light and a photoradical polymerization initiator configured to generate a radical when irradiated with ultraviolet light. (SiO 4 / 2) ... (3)

2. The coating agent according to claim 1, wherein the molar ratio of the content of the Ta structural unit to the sum of the content of the Ta structural unit and the content of the Tc structural unit in the silsesquioxane is 20 mol% or more and 45 mol% or less.

3. The coating agent according to claim 1, wherein the weight-average molecular weight of the silsesquioxane is 2,000 or more and 15,000 or less.

4. The coating agent according to claim 1, wherein the silsesquioxane comprises the Ta structural unit, the Tc structural unit, and the Q structural unit represented by the composition formula (3).

5. The coating agent according to claim 1, wherein the (meth)acrylate has an isocyanuric ring.

6. The coating agent according to claim 1, wherein the weight-average molecular weight of the silsesquioxane is 4,000 or more and 15,000 or less.

7. The coating agent according to claim 1, wherein the weight-average molecular weight of the silsesquioxane is 5,000 or more and 10,000 or less.

8. The coating agent according to claim 1, wherein the content of silsesquioxane is 30 parts by mass or more and 75 parts by mass or less per 100 parts by mass of (meth)acrylate.

9. A base material made of resin, A resin member having a coating film formed on the substrate, The coating film is composed of a cured product of the coating agent described in any one of claims 1 to 8. The coating film comprises a surface layer exposed on the surface of the resin member, It has an inner layer interposed between the surface layer and the substrate, A resin member wherein the average concentration of Si atoms in the surface layer is higher than the average concentration of Si atoms in the inner layer.

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