Optical coating agent and film for urethane-based primer

Abstract

To provide a coating agent that can form a film with superior weather-resistant adhesion to a urethane-based primer layer, is resistant to loss of transparency under exposure to light, and further exhibits a high refractive index, and also to provide a film for a urethane-based primer.SOLUTION: A coating agent of the present invention is used for coating on a urethane-based primer layer, and comprises at least the following components: (A) an epoxy acrylate, (B) an aromatic urethane acrylate, and (C) one or more selected from the group consisting of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate and a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, wherein the epoxy acrylate has a biphenyl moiety in the molecule.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an optical coating agent used for coating a urethane-based primer layer, and a film for a urethane-based primer. [Background technology]

[0002] Active energy ray-curable resin compositions that can be cured by active energy rays such as ultraviolet rays are used, for example, in coating agents and can form films on various substrates. Such films can exhibit various functions depending on the characteristics of the components contained in the coating agent. In order to improve the functionality of such films, various curable resin compositions have been proposed as coating agents.

[0003] As a coating agent containing a curable resin composition, for example, Patent Document 1 proposes an active energy ray-curable composition whose main component is a urethane (meth)acrylate obtained by reacting a polyol, a polyether polyol, a polyisocyanate, and a (meth)acrylate having a hydroxyl group. Because the coating agent made from such a composition is urethane-based, it is said to be capable of forming a film that is excellent in crack resistance and elasticity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-189651 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, a urethane primer layer has also been coated with a coating agent containing an active energy ray-curable resin composition. In this case, the film formed on the urethane primer layer is required to have excellent adhesion.

[0006] However, the inventors have found that conventional coating agents have a problem in that their weather-resistant adhesion to a urethane-based primer layer is easily reduced. That is, even if a coating film (film) is formed on a urethane-based primer layer using a conventional coating agent, the adhesion to the urethane-based primer layer gradually decreases when the surface is exposed to sunlight or other light for a long period of time (e.g., outdoor exposure). Furthermore, the film surface is prone to a decrease in transparency when exposed to sunlight or other light for a long period of time. While it is possible to improve weather resistance by selecting the types of components contained in the coating agent, this can also result in a decrease in transparency and refractive index. In this case, it is difficult to apply the coating agent to optical applications, for example, and there is a problem in that its applications are limited. From this perspective, there has been a need for a coating agent that has excellent weather-resistant adhesion to a urethane-based primer layer, is resistant to a decrease in transparency even when exposed to light, and is capable of forming a film with a high refractive index.

[0007] The present invention has been made in view of the above, and aims to provide a coating agent and a coating for a urethane primer that can form a film that has excellent weather-resistant adhesion to a urethane primer layer, that is resistant to loss of transparency even when exposed to light, and that has a high refractive index. [Means for solving the problem]

[0008] As a result of extensive research into achieving the above object, the present inventors have found that the above object can be achieved by using a specific epoxy acrylate, an aromatic urethane acrylate, and a polyfunctional acrylic compound as essential components, and have thus completed the present invention.

[0009] That is, the present invention includes, for example, the subject matter described in the following sections. Item 1 An optical coating agent used for coating a urethane-based primer layer, The following components (A), (B) and (C) (A) component: epoxy acrylate, (B) component: aromatic urethane acrylate; Component (C): at least one selected from the group consisting of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, and a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate; Contains at least The epoxy acrylate has a biphenyl moiety in the molecule. Section 2 Item 2. The optical coating agent according to item 1, wherein the epoxy acrylate has two or more acryloyl groups in the molecule. Section 3 Item 2. The optical coating agent according to item 1, wherein the aromatic urethane acrylate has two or more acryloyl groups in the molecule. Section 4 Item 4. A urethane-based primer coating film containing a cured product of the optical coating agent according to any one of Items 1 to 3. Section 5 Item 4. Use of the optical coating agent according to any one of items 1 to 3 in a urethane-based primer. Section 6 Item 4. A method for using a coating agent or a method for forming a film, comprising a step of forming a film on a urethane-based primer layer using the optical coating agent according to any one of Items 1 to 3. [Effects of the Invention]

[0010] The coating agent of the present invention can form a film that has excellent weather-resistant adhesion to a urethane-based primer layer, and in addition, is resistant to deterioration in transparency even when exposed to light, and can have a high refractive index. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0012] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. In addition, in this specification, numerical values ​​connected with "to" mean a numerical range that includes the numbers before and after "to" as the lower and upper limits.

[0013] The optical coating agent of the present invention is an optical coating agent used for coating a urethane-based primer layer, and comprises the following components (A), (B), and (C): (A) component: epoxy acrylate, (B) component: aromatic urethane acrylate; Component (C): at least one selected from the group consisting of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, and a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate; Here, the epoxy acrylate has a biphenyl moiety in the molecule.

[0014] The optical coating agent of the present invention (hereinafter sometimes simply referred to as "the coating agent of the present invention" or "coating agent") can be used to form a film on a urethane-based primer layer. The coating agent of the present invention contains the aforementioned components (A), (B), and (C), and thus can form a film with excellent weather-resistant adhesion to the urethane-based primer layer, and furthermore, is resistant to loss of transparency even when exposed to light, and can have a high refractive index. Therefore, a film formed from the coating agent of the present invention maintains high adhesion to the urethane-based primer layer and high transparency even when exposed to outdoor environments.

[0015] Component (A) Component (A) is an epoxy acrylate containing a biphenyl moiety in the molecule. By including component (A) in the coating agent, the film obtained from the coating agent has excellent weather-resistant adhesion to the urethane primer layer and is less likely to lose transparency even when exposed to light.

[0016] In the epoxy acrylate, the number of biphenyl moieties present in the molecule is, for example, one or more, preferably four or less, more preferably three or less, even more preferably two or less, and particularly preferably one.

[0017] An example of a biphenyl moiety is a group formed by removing at least one hydrogen atom from each benzene ring of biphenyl. Such a biphenyl moiety is preferably divalent, for example, a moiety derived from a divalent group represented by "-Ph-Ph-" (Ph represents CH). The divalent group represented by "-Ph-Ph-" is, for example, a group formed by removing hydrogen atoms at the para positions of both benzene rings.

[0018] The biphenyl moiety may be, for example, a group formed by removing one hydrogen atom from each hydroxyl group of biphenol. In this case, the biphenyl moiety is, for example, a moiety derived from a divalent group represented by "-O-Ph-Ph-O-" (Ph represents CH). The divalent group represented by "-O-Ph-Ph-O-" is, for example, a group formed by substituting oxygen for the hydrogen atoms at the para positions of both benzene rings.

[0019] In the divalent group forming the biphenyl moiety, at least one hydrogen atom of at least one or both of the two benzene rings may be substituted with another substituent. The other substituent is not particularly limited, and examples thereof include a linear or branched alkyl group having about 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.

[0020] The epoxy acrylate has, in addition to the biphenyl moiety, a group derived from an epoxy group or a glycidyl group. The number of the groups derived from the epoxy group or the glycidyl group in the epoxy acrylate molecule is preferably 2 or more, and is preferably 4 or less, more preferably 3 or less, and particularly preferably 2.

[0021] The group derived from an epoxy group or a glycidyl group is, for example, a group represented by the following formula (1): —CH2—CH(OH)—CH2— (1) or a divalent group represented by The following equation (2) —CH2—CH(OH)— (2) By having a group derived from an epoxy group or a glycidyl group in the molecule, the epoxy acrylate tends to give a coating with an appropriate hardness and excellent weather-resistant adhesion to a urethane primer layer.

[0022] It is preferable that the epoxy acrylate does not have a urethane bond in the molecule.

[0023] The epoxy acrylate has at least one acryloyl group in the molecule, and preferably two or more acryloyl groups in the molecule, which makes it easier for the resulting coating to have an appropriate hardness and excellent weather-resistant adhesion to the urethane primer layer.

[0024] In this specification, the term "acryloyl group" includes not only an acryloyl group but also a methacryloyl group.

[0025] The epoxy acrylate more preferably has four or less acryloyl groups in the molecule, even more preferably three or less, and particularly preferably two.

[0026] The acryloyl groups are preferably bonded to both ends of the epoxy acrylate molecule by covalent bonds, for example.

[0027] The acryloyl group can be directly bonded to the group derived from the epoxy group or glycidyl group described above. For example, the oxygen of the acryloyl group can be directly bonded to the group represented by formula (1) or formula (2).

[0028] A specific example of the epoxy acrylate is a compound represented by the following general formula (3).

[0029] [ka]

[0030] Here, in equation (3), R 1 and R 2 are the same or different and are alkyl groups having 1 to 10 carbon atoms, and m and n are the same or different and are integers of 0 to 4. When m is 0, R 1 means that there is no 2Therefore, when m and n are 0, this means that there are four hydrogen atoms in each benzene ring of the biphenyl moiety (i.e., the biphenyl moiety is a divalent group represented by -CH-CH-).

[0031] R 1 and R 2 are the same or different and are preferably linear or branched alkyl groups having 1 to 10 carbon atoms, more preferably alkyl groups having 1 to 4 carbon atoms, and even more preferably alkyl groups having 1 to 2 carbon atoms. m and n are preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. When m and n are 1, R 1 and R 2 is preferably bonded at the ortho position relative to the epoxy acrylate moiety in the formula (3).

[0032] In the compound represented by formula (3), the biphenyl moiety is a group formed by removing one hydrogen atom from each hydroxyl group of the biphenol, i.e., the biphenyl moiety is a divalent group represented by "-O-Ph-Ph-O-" (i.e., -O-C6H4-C6H4-O-).

[0033] The coating agent of the present invention may contain one type of component (A) alone or two or more types. When the coating agent of the present invention contains two types of component (A), for example, it may contain two types of compounds represented by formula (3). Specific examples include a compound in which m and n are 0 in formula (3) and a compound in which m and n are both 1 and R 1 and R 2 and (b) are both methyl groups (the two methyl groups are bonded at the ortho position relative to the epoxy acrylate moiety).

[0034] The method for producing the epoxy acrylate (component A) is not particularly limited, and for example, a wide variety of known production methods can be employed. For example, the epoxy acrylate (component A) can be produced by reacting an epoxy compound with an acrylic compound such as acrylic acid in the presence of a catalyst. Examples of epoxy compounds include compounds having epoxide moieties at both ends of a biphenyl moiety, such as the biphenyl-type epoxy resin "YX4000" series from Mitsubishi Chemical Corporation. Examples of catalysts include tetrabutylammonium bromide.

[0035] (B) Component Component (B) is an aromatic urethane acrylate. If the coating agent of the present invention does not contain component (B), the weather-resistant adhesion to the urethane primer layer will decrease, and in particular the refractive index will decrease significantly.

[0036] The type of aromatic urethane acrylate is not particularly limited, and for example, a wide range of known aromatic urethane acrylates can be applied to the present invention.

[0037] The aromatic urethane acrylate is an acrylate compound having an aromatic moiety and a urethane bond in the molecule. That is, the aromatic urethane acrylate of component (B) is a compound having a (meth)acryloyl group, an aromatic moiety, and a urethane bond in the molecule. In this specification, "(meth)acryl" means "acryl" or "methacryl."

[0038] The aromatic urethane acrylate preferably has two or more acryloyl groups in the molecule. In the aromatic urethane acrylate, the number of acryloyl groups is preferably at least two, more preferably at least three, and is preferably eight or less, more preferably six or less, and even more preferably five or less.

[0039] The molecular weight of the aromatic urethane acrylate (molecular weight based on molar mass) is preferably 1,000 to 1,500, for example.

[0040] The aromatic urethane acrylate can be produced, for example, by a known production method. For example, an aromatic urethane acrylate can be obtained by reacting an alcohol compound having a hydroxyl group and an acryloyl group with an isocyanate compound. In this case, it is preferable that either one or both of the alcohol compound and the isocyanate compound have an aromatic moiety. The alcohol compound is preferably a polyhydric alcohol compound, and the isocyanate compound is preferably a polyhydric isocyanate compound. A wide range of known compounds can be used as the polyhydric alcohol compound and the isocyanate compound.

[0041] Examples of alcohol compounds having an aromatic moiety include epoxy group ring-opening products of bisphenol A epoxy resins (for example, compounds having the same structure as the compound represented by the following formula (4)), as well as "Sanyo Chemical Industries' Newpol BPE (registered trademark) series and Newpol BP (registered trademark) series" obtained by adding ethylene oxide or propylene oxide to bisphenol A, and further examples include polyester polyols containing terephthalic acid or isophthalic acid.

[0042] [ka]

[0043] Examples of isocyanate compounds having an aromatic moiety include 1,3-bis(isocyanatemethyl)benzene, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, tolylene diisocyanate, metaxylylene diisocyanate, and tetramethylxylene diisocyanate.

[0044] An example of a method for producing an aromatic urethane acrylate is to react a compound having the same structure as the compound represented by formula (4) with a polyvalent isocyanate compound having an aromatic moiety. Alternatively, an aromatic urethane acrylate can be produced by reacting pentaerythritol acrylate with a polyvalent isocyanate compound having an aromatic moiety.

[0045] The aromatic urethane acrylate can be obtained from a commercial product, for example, the aromatic urethane acrylate "EBECRYL" manufactured by Daicel Allnex.

[0046] The coating agent of the present invention may contain one type of component (B) alone, or may contain two or more types.

[0047] (C) Component Component (C) is a polyfunctional acrylic compound selected from the group consisting of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, and a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate. If the coating agent of the present invention does not contain component (C), the hardness of the film may be insufficient, making it impossible to obtain the desired film.

[0048] In a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, the ratio of the two is not particularly limited, and the effect of component (C) can be exerted regardless of the mixing ratio. From the viewpoint of ease of availability, the content of dipentaerythritol hexaacrylate is preferably 40% by mass or more, more preferably 50% by mass or more, and can be 99% by mass or less.

[0049] In the mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, the ratio of the two is not particularly limited, and the effect of component (C) can be exerted regardless of the mixing ratio. From the viewpoint of ease of availability, the content of pentaerythritol tetraacrylate is preferably 30% by mass or more, more preferably 40% by mass or more, and can be 99% by mass or less.

[0050] The method for producing component (C) is not particularly limited, and any known production method can be used. Component (C) can also be obtained commercially. Examples of commercially available products of component (C) include "KAYARAD DPHA" (registered trademark) from Nippon Kayaku Co., Ltd. and "New Frontier PET-3" (registered trademark) from Daiichi Kogyo Seiyaku Co., Ltd.

[0051] coating agent The coating agent of the present invention contains components (A), (B), and (C), and as a result, a film formed from the coating agent exhibits excellent weather-resistant adhesion to a urethane primer layer, is resistant to loss of transparency even when exposed to light, and has a high refractive index.

[0052] In the coating agent of the present invention, component (A) and component (B) each contain a radically polymerizable double bond moiety such as an acryloyl group, and therefore, the coating agent cures upon heating or active energy rays, thereby forming a coating on the substrate.

[0053] In the coating agent of the present invention, the content of component (A) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the total mass of components (A), (B), and (C), in order to more easily improve the weather-resistant adhesion of the resulting coating to the urethane primer layer, and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, and particularly preferably 50 parts by mass or less. Note that the total mass of 100 parts by mass of components (A), (B), and (C) refers to the value converted into solid content, excluding volatile components such as solvents.

[0054] In the coating agent of the present invention, the content of component (B) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more, per 100 parts by mass of the total mass of components (A), (B), and (C), in order to improve the weather-resistant adhesion and transparency of the resulting coating to the urethane primer layer, and is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 55 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0055] In the coating agent of the present invention, the content of component (C) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, per 100 parts by mass of the total mass of components (A), (B), and (C), because this tends to keep the haze and refractive index of the resulting coating within an appropriate range. The content is also preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 25 parts by mass or less.

[0056] The coating agent of the present invention may contain components other than the components (A), (B), and (C), such as a polymerization initiator and a solvent.

[0057] Examples of the polymerization initiator include a photopolymerization initiator and a polymerization initiator using active energy rays such as ultraviolet rays.

[0058] Examples of the photopolymerization initiator include aromatic ketones such as benzophenone, aromatic compounds such as anthracene and α-chloromethylnaphthalene, and sulfur compounds such as diphenyl sulfide and thiocarbamate.

[0059] Examples of polymerization initiators using active energy rays other than visible light, such as ultraviolet rays, include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethan-1-one, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzil dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl- Examples of such an alkyl ester include 1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone).

[0060] Commercially available active energy ray polymerization initiators include, for example, Omnirad 184, 369, 651, 500, 819, 907, 784, 2959, 1000, 1300, 1700, 1800, and 1850 manufactured by IGM Resins BV, Lucirin TPO manufactured by BASF, Ubecryl P36 manufactured by UCB, Esacure KIP150, KIP100F, KT37, KT55, KTO46, TZT, and KIP75LT manufactured by Fratelli Lamberti, and Kayacure DETX manufactured by Nippon Kayaku Co., Ltd.

[0061] The content of the polymerization initiator varies depending on the type, etc., but for example, the content of the polymerization initiator is preferably 0.1 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 5 parts by mass, relative to 100 parts by mass of the total mass of the (A), (B), and (C) components.

[0062] When the coating agent contains a solvent, examples of the solvent include hydrocarbon solvents such as benzene, toluene, and xylene; ketone solvents such as acetone, methyl ethyl ketone, and isophorone; alcohol solvents such as tert-butyl alcohol, benzyl alcohol, phenoxyethanol, and phenylpropylene glycol; halogenated hydrocarbon solvents such as methylene chloride and chloroform; ether solvents such as 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, and anisole; ester solvents such as ethyl acetate, propyl acetate, ethyl carbitol acetate, and butyl carbitol acetate; and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide.

[0063] The coating agent may also contain other additives, such as a light stabilizer, an ultraviolet absorber, a catalyst, a leveling agent, an antifoaming agent, a polymerization accelerator, an antioxidant, a flame retardant, an infrared absorber, an antistatic agent, a slip agent, a plasticizer, and a dispersant, as necessary.

[0064] The method for preparing the coating agent is not particularly limited, and the coating agent can be prepared, for example, by mixing the components (A), (B), and (C) and other components added as needed in predetermined amounts.

[0065] A film can be formed using a coating agent. The method for forming the film is not particularly limited, and for example, a wide variety of known methods can be employed. For example, a method including a step of forming a film on a urethane-based primer layer using an optical coating agent can be employed. Specifically, a coating agent is applied to a urethane-based primer layer to form a coating film, and the coating film is then irradiated with active energy rays, thereby curing the coating film and forming a film. Therefore, the film contains a cured product of the optical coating agent of the present invention.

[0066] Examples of active energy rays include high-pressure mercury lamps, electron beams, gamma rays, carbon arc lamps, xenon lamps, metal halide lamps, etc. When curing is performed by heating, the composition can be cured by heating to a temperature range of 60 to 250°C.

[0067] The method for applying the coating agent onto the urethane primer layer is not particularly limited, and a wide variety of known methods can be used, for example.Specific examples include a method of applying the coating agent onto the urethane primer layer using a bar coater or the like, and a method of spraying the coating agent onto the urethane primer layer.

[0068] The thickness of the film formed by the coating agent is not particularly limited, and is, for example, 1 to 20 μm, and preferably 2 to 10 μm.

[0069] The coating formed from the coating agent of the present invention exhibits excellent adhesion to a urethane-based primer layer even when exposed to light, and its adhesion to a urethane-based primer layer is unlikely to decrease, even under carbon arc exposure conditions for 100 hours, for example. Furthermore, the haze is unlikely to change before and after exposure, and the film has high transparency. Furthermore, the coating formed from the coating agent of the present invention has a high refractive index. Therefore, the optical coating agent of the present invention is suitable for use with urethane-based primers. In other words, the coating formed from the coating agent (a coating containing a cured product of the optical coating agent) is suitable as a coating for a urethane-based primer.

[0070] The haze of the film formed by the coating agent is unlikely to change even when the film is exposed to light for a long period of time. For example, even if the film is exposed to carbon arc exposure for 100 hours, the change in haze before and after exposure can be less than 0.5.

[0071] The refractive index of the film formed by the coating agent is preferably 1.555 or more, for example, from the viewpoint of being suitable for optical applications.

[0072] The type of urethane-based primer that forms a film using the coating agent is not particularly limited, and a wide variety of known urethane-based primers can be used. Specific examples of urethane-based primers include known aqueous urethane-based primers, solvent-based urethane-based primers, and ultraviolet-curable urethane-based primers. A wide variety of known methods can be used to form the urethane-based primer layer. Specific examples include a method in which the urethane-based primer is applied to a substrate to a desired thickness and then dried. The substrate is not particularly limited, and a wide variety of films used as optical components, optical displays, and the like can be used.

[0073] The thickness of the urethane primer layer is not particularly limited, and can be set in the range of 0.1 to 5 μm, for example, from the viewpoint of optical function.

[0074] The coating agent of the present invention is suitable for optical applications. For example, a member having a film formed from such a coating agent is preferably an optical member such as an optical film or an optical display. The optical member is incorporated into, for example, a display device. Examples of the display device include a liquid crystal display, a plasma display, and an organic EL display.

[0075] In specifying the inventions included in the present disclosure, the components (properties, structures, functions, etc.) described in each embodiment of the present disclosure may be combined in any manner. In other words, the present disclosure includes all subject matter consisting of all combinations of the components that can be combined as described herein. [Example]

[0076] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0077] (raw materials) In each of the Examples and Comparative Examples, the following raw materials were used to prepare the coating agents.

[0078] Component (A): Epoxy acrylate (A-1) Epoxy acrylate A-1 was prepared by the following method: First, a flask equipped with a thermometer, a stirrer, and a water-cooled condenser was charged with 186 parts by weight of Mitsubishi Chemical Corporation's "YX-4000" biphenyl-type epoxy resin, 72 parts by weight of acrylic acid, 0.26 parts by weight of 4F-methoxyphenol as a polymerization inhibitor, 1.3 parts by weight of tetrabutylammonium bromide as a catalyst, and 111 parts by weight of butyl acetate, and the reaction was carried out at a reaction temperature of 95 to 110°C until the epoxy equivalent reached 10,000 or more, yielding a solution containing epoxy acrylate A-1 (solid concentration 70% by mass).

[0079] Comparative epoxy acrylate (a-1) Epoxy acrylate a-1 was prepared by the following method. First, in a flask equipped with a thermometer, a stirrer, and a water-cooled condenser, 72 parts by weight of acrylic acid, 0.26 parts by weight of 4-methoxyphenol as a polymerization inhibitor, and 1.3 parts by weight of tetrabutylammonium bromide as a catalyst were added to 189 parts by weight of "jER828 (registered trademark)" manufactured by Mitsubishi Chemical Corporation, which is an epoxy resin having no biphenyl moiety, and the reaction was carried out at a reaction temperature of 95 to 110 ° C until the epoxy equivalent reached 10,000 or more. 112 parts by weight of methyl ethyl ketone was added for dilution, and a solution containing epoxy acrylate a-1 (solid concentration 70 mass%) was obtained.

[0080] Comparative epoxy acrylate (a-2) Epoxy acrylate a-2 was prepared by the following method: First, a flask equipped with a thermometer, a stirrer, and a water-cooled condenser was charged with 210 parts by weight of "NC-6000" manufactured by Nippon Kayaku Co., Ltd., an epoxy resin having no biphenyl moiety, 72 parts by weight of acrylic acid, 0.28 parts by weight of 4-methoxyphenol as a polymerization inhibitor, 1.4 parts by weight of tetrabutylammonium bromide as a catalyst, and 122 parts by weight of butyl acetate, and the reaction was carried out at a reaction temperature of 95 to 110°C until the epoxy equivalent reached 10,000 or more, to obtain a solution containing epoxy acrylate a-2 (solid concentration 70% by mass).

[0081] Component (B): Aromatic urethane acrylate (B-1) Aromatic urethane acrylate B-1 was prepared by the following method. First, 189 parts by weight of Mitsubishi Chemical Corporation's "jER828 (registered trademark)" was added to a flask equipped with a thermometer, a stirrer, and a water-cooled condenser, and 72 parts by weight of acrylic acid, 0.52 parts by weight of 4-methoxyphenol as a polymerization inhibitor, and 1.3 parts by weight of tetrabutylammonium bromide as a catalyst were added. The reaction was carried out at a reaction temperature of 95 to 110 ° C until the epoxy equivalent reached 10,000 or more. Next, 47 parts by weight of Mitsui Chemicals' aromatic isocyanate "Takenate 500 (registered trademark)" and 135 parts by weight of methyl isobutyl ketone were added, and the reaction was carried out at a reaction temperature of 50 to 70 ° C until the free isocyanate content was 0.1% or less, obtaining a solution containing aromatic urethane acrylate B-1 (solids concentration 70% by mass).

[0082] Component (B): Aromatic urethane acrylate (B-2) Aromatic urethane acrylate B-2 was prepared by the following method. First, 1,151 parts by weight of acrylic acid, 604 parts by weight of pentaerythritol (manufactured by Koei Chemical Industry Co., Ltd.), 43.9 parts by weight of paratoluenesulfonic acid, 2.1 parts by weight of the polymerization inhibitor 4-methoxyphenol, and 552 parts by weight of toluene were added to a flask equipped with a thermometer, a stirrer, and a water-cooled condenser and mixed. Subsequently, under reduced pressure, the reaction temperature was maintained at approximately 100°C while air was blown in, and the reaction was continued until 75% of the total hydroxyl groups in the pentaerythritol were esterified. The reaction was continued while removing condensed water. After the reaction was completed, 353 parts by weight of toluene was added. A 20% by weight aqueous solution of sodium hydroxide, equivalent to 1.1 times the molar amount of the acid content of the reaction solution to which toluene had been added, was added with stirring to neutralize the solution, thereby removing excess acrylic acid and paratoluenesulfonic acid. The organic layer was then separated and washed with water by adding 10 parts by weight of water per 100 parts by weight of the organic layer with stirring. Thereafter, the organic layer was separated again, and the toluene was distilled off by heating under reduced pressure. The resulting pentaerythritol acrylate was 837 parts by weight, and had a hydroxyl value of 190 mg KOH / g. Next, 190.5 parts by weight of aromatic isocyanate "Takenate 500 (registered trademark)" manufactured by Mitsui Chemicals, Inc. and 440 parts by weight of methyl ethyl ketone were added to 837 parts by weight of the resulting pentaerythritol acrylate having a hydroxyl value of 190 mg KOH / g, and the reaction was carried out at a reaction temperature of 50 to 70 ° C until the free isocyanate content was 0.1% or less, to obtain a solution containing aromatic urethane acrylate B-2 (solid concentration 70% by mass).

[0083] Comparative urethane acrylate (b-1) Aliphatic urethane acrylate b-1 was prepared using the following method. First, 636 parts by weight of acrylic acid, 300 parts by weight of pentaerythritol (manufactured by Koei Chemical Industry Co., Ltd.), 23.4 parts by weight of paratoluenesulfonic acid, 1.1 parts by weight of the polymerization inhibitor 4-methoxyphenol, and 299 parts by weight of toluene were added to a flask equipped with a thermometer, a stirrer, and a water-cooled condenser and mixed. Subsequently, under reduced pressure, the reaction temperature was maintained at approximately 100°C while air was blown in, and the reaction was continued until 75% of the total hydroxyl groups in the pentaerythritol were esterified. The reaction was continued while removing condensed water. After completion of the reaction, 191 parts by weight of toluene was added. A 20% by weight aqueous solution of sodium hydroxide, equivalent to 1.1 times the molar amount of the acid content of the reaction solution to which toluene had been added, was added with stirring to neutralize the mixture, thereby removing excess acrylic acid and paratoluenesulfonic acid. The organic layer was then separated and washed with water by adding 10 parts by weight of water per 100 parts by weight of the organic layer with stirring. The organic layer was then separated again and heated under reduced pressure to distill off the toluene. The resulting pentaerythritol acrylate was 920 parts by weight and had a hydroxyl value of 120 mg KOH / g. Next, 208.3 parts by weight of isophorone diisocyanate and 0.15 parts by weight of dibutyltin dilaurate as a catalyst were added to 920 parts by weight of the resulting pentaerythritol acrylate with a hydroxyl value of 120 mg KOH / g, and the reaction was carried out at a reaction temperature of 50 to 70 ° C until the free isocyanate content was 0.1% or less. 484 parts by weight of methyl ethyl ketone was added for dilution, and a solution containing aliphatic urethane acrylate b-1 (solid concentration 70% by mass) was obtained.

[0084] Component (C): Polyfunctional acrylic compound C-1: Dipentaerythritol acrylate (Nippon Kayaku Co., Ltd. "KAYARAD DPHA" (registered trademark)) = a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate C-2: Pentaerythritol acrylate (Dai-ichi Kogyo Seiyaku Co., Ltd. "New Frontier PET-3" (registered trademark)) = a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate

[0085] Example 1 A coating agent was prepared using the raw materials shown in Example 1 of the formulation in Table 1. Specifically, 100 parts by mass of a mixture was prepared by mixing 40 parts by mass of epoxy acrylate A-1 as component (A), 40 parts by mass of aromatic urethane acrylate B-1 as component (B), and 20 parts by mass of C-1 as component (C) in terms of solid content. 4 parts by mass of Omnirad184 (IGM Resins BV) as a polymerization initiator and 66 parts by mass of methyl ethyl ketone as a solvent were mixed with this mixture to obtain a coating agent with a concentration of 50% by mass.

[0086] Example 2 A coating agent with a concentration of 50 mass % was obtained in the same manner as in Example 1, except that the component (B) was changed to aromatic urethane acrylate B-2 as shown in Table 1.

[0087] Example 3 A coating agent with a concentration of 50 mass % was obtained in the same manner as in Example 1, except that the component (C) was changed to C-2 as shown in Table 1.

[0088] Example 4 As shown in Table 1, a coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the amount of epoxy acrylate A-1 as component (A) was changed to 60 parts by mass, and the amount of aromatic urethane acrylate B-1 as component (B) was changed to 20 parts by mass.

[0089] Example 5 As shown in Table 1, a coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the amount of epoxy acrylate A-1 as component (A) was changed to 20 parts by mass, and the amount of aromatic urethane acrylate B-1 as component (B) was changed to 60 parts by mass.

[0090] Example 6 As shown in Table 1, a coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the (A) component was changed to 50 parts by mass of epoxy acrylate A-1, the (C) component was changed to 10 parts by mass of C-1, and 61 parts by mass of methyl ethyl ketone was mixed as the solvent.

[0091] Example 7 As shown in Table 1, a coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the (A) component was changed to 30 parts by mass of epoxy acrylate A-1, the (C) component was changed to 30 parts by mass of C-1, and 70 parts by mass of methyl ethyl ketone was mixed as the solvent.

[0092] (Comparative Example 1) A coating agent with a concentration of 50 mass % was obtained in the same manner as in Example 1, except that the component (A) was changed to epoxy acrylate a-1 as shown in Table 1.

[0093] (Comparative Example 2) A coating agent with a concentration of 50 mass % was obtained in the same manner as in Example 1, except that the component (A) was changed to epoxy acrylate a-2 as shown in Table 1.

[0094] (Comparative Example 3) A coating agent with a concentration of 50 mass % was obtained in the same manner as in Example 1, except that the component (B) was changed to aliphatic urethane acrylate b-1 as shown in Table 1.

[0095] (Creation of the coating) Using the coating agents prepared in each Example and Comparative Example, a film was formed on a urethane primer layer according to the following procedure. First, a PET substrate (Lumirror T60, manufactured by Toray Industries, Inc.) was prepared as the substrate. A urethane primer solution was applied to the corona discharge-untreated side of the PET substrate using a bar coater to a dry film thickness of 2 to 8 μm. This was pre-dried at 80°C for 10 minutes, and then dried at 150°C for 10 minutes to form a urethane primer layer. The urethane primer solution was prepared by mixing 36 parts by weight of Elastron H-15 (registered trademark, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a thermally reactive urethane water dispersion, 2 parts by weight of a 5% aqueous sodium bicarbonate solution, 1 part by weight of Elastron CAT-21 (registered trademark, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a thermal polymerization catalyst, and 61 parts by weight of dilution water, and the pH was adjusted to approximately 6. Next, the coating agent prepared in each Example and Comparative Example was applied to the urethane primer layer to a film thickness of approximately 4 to 7 μm in a dry state to form a coating film. Next, a high-pressure mercury lamp 80W / cm 2 Using an integrated illuminance of 150 mJ / cm 2 The coating was cured by irradiating it with ultraviolet light in a nitrogen atmosphere at 400°C, thereby forming a film containing a cured product of the coating agent on the urethane primer.

[0096] (Evaluation method) <Weather-resistant adhesion test> The weathering adhesion test was carried out based on a 2 mm cross-cut test in accordance with JIS K5400-8.5:1990. Specifically, the film obtained in the above "Preparation of film" was measured using a Sunshine Weather Meter S80 (manufactured by Suga Test Instruments) at an irradiance of 300-400 nm: 78.5 W / m 2 After this treatment, the remaining rate of the film on the PET substrate was calculated using the following formula: Residual rate (%) = 100 - (number of peeled squares) Based on the calculated remaining rate, the weather-resistant adhesion was evaluated according to the following criteria. ≪Judgment criteria≫ A: Residual rate is 50% or more B: Residual rate is 10% or more but less than 50% C: Residual rate is less than 10%

[0097] <Haze change> The haze of the resulting coating was measured using a turbidity meter (NDH4000, manufactured by Nippon Denshoku) in accordance with JIS K 7136: 2000. This haze measurement was carried out before and after the weather-resistant adhesion test described above, and the amount of change in haze was calculated to evaluate the stability of the haze according to the following criteria. ≪Judgment criteria≫ A: Δ was less than 0.3, and excellent transparency was maintained even when exposed to light. B: Δ was 0.3 or more and less than 0.5, and excellent transparency was maintained even when exposed to light. C: Δ was 0.5 or more, and the transparency decreased when exposed to light.

[0098] <Refractive index> The refractive index of the obtained film was measured at a wavelength of 589 nm using a refractive index measuring device (product name: Prism Coupler) manufactured by Metricon Corporation. Based on the obtained refractive index value, evaluation was performed according to the following criteria. ≪Judgment criteria≫ A: 1.560 or more B: 1.555 or more and less than 1.560 C: Less than 1.555

[0099] Table 1 shows the compounding conditions for the coating agents prepared in each example and comparative example, as well as the evaluation results for the weather-resistant adhesion, haze, and refractive index of the resulting films. Note that blank spaces in the compounding conditions in Table 1 indicate that the raw material was not used.

[0100] As can be seen from Table 1, the coating agents obtained in the examples contain components (A), (B), and (C), and therefore were able to form films with excellent weather-resistant adhesion to urethane primer layers. Furthermore, it was also shown that the coating agents obtained in the examples are resistant to loss of transparency even when exposed to light, and can maintain high transparency even when exposed outdoors. It was also shown that the coating agents obtained in the examples can have a high refractive index.

[0101]

Table 1

Claims

1. An optical coating agent used for coating a urethane-based primer layer, The following components (A), (B) and (C): Component (A): epoxy acrylate, (B) component: an aromatic urethane acrylate; Component (C): at least one selected from the group consisting of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, and a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate; Contains at least The epoxy acrylate has a biphenyl moiety in the molecule.

2. 2. The optical coating agent according to claim 1, wherein the epoxy acrylate has two or more acryloyl groups in the molecule.

3. 2. The optical coating agent according to claim 1, wherein the aromatic urethane acrylate has two or more acryloyl groups in the molecule.

4. A urethane-based primer film comprising a cured product of the optical coating agent according to any one of claims 1 to 3.

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