Optical coating agent and film for urethane-based primer

Abstract

To provide a coating agent that can form a film with superior adhesion as well as superior light-resistant adhesion to a urethane-based primer layer under hot and humid conditions, is resistant to loss of transparency in the hot and humid conditions, and further enables formation of a film having a high refractive index.SOLUTION: A coating agent of the present invention comprises at least the following components: (A) an oligomer, (B) an aromatic urethane acrylate, (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, and (D) an acryl compound having a biphenyl moiety, wherein the oligomer has a phenol novolac structure in the main chain and includes at least one acryloyl group.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 urethane-based coating agents have a problem in that their adhesion to a urethane primer layer is easily reduced in a humid and hot environment (i.e., in an environment of high temperature and humidity). In addition, conventional urethane-based coating agents have a problem in that their weather-resistant adhesion to a urethane primer layer is easily reduced. That is, even if a coating film (film) is formed on a urethane primer layer using a conventional coating agent, the adhesion to the urethane primer layer gradually decreases when the surface is exposed to sunlight or the like for a long period of time (e.g., outdoor exposure). On the other hand, although it is possible to improve adhesion and light-resistant adhesion in a humid and hot environment 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 adhesion to a urethane primer layer even in a humid and hot environment, excellent light-resistant adhesion to a urethane primer layer, is resistant to loss of transparency even in a humid and hot environment, 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 has an object to provide a coating agent and a film for a urethane primer that can form a film that has excellent adhesion to a urethane primer layer even in a humid and hot environment, and that also has excellent light-resistant adhesion to a urethane primer layer, that is less likely to lose transparency even in a humid and hot environment, 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 oligomer, an aromatic urethane acrylate, a polyfunctional acrylic compound, and an acrylic compound having a biphenyl moiety 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), (C) and (D) Component (A): an oligomer, (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; Component (D): an acrylic compound having a biphenyl moiety; Contains at least The oligomer is an optical coating agent, the main chain of which has a phenol novolac structure and at least one acryloyl group. Section 2 Item 2. The optical coating agent according to Item 1, wherein the oligomer has a group derived from an epoxy group or a glycidyl group. Section 3 Item 3. The optical coating agent according to item 1 or 2, wherein the aromatic urethane acrylate has two or more acryloyl groups in the molecule. Section 4 4. The optical coating agent according to any one of items 1 to 3, wherein the acrylic compound having a biphenyl moiety has one or more acryloyl groups in the molecule. Section 5 Item 5. A urethane-based primer coating film containing a cured product of the optical coating agent according to any one of items 1 to 4. Section 6 Item 5. Use of the optical coating agent according to any one of items 1 to 4 in a urethane-based primer. Section 7 Item 5. 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 4. [Effects of the Invention]

[0010] The coating agent of the present invention can form a film that has excellent adhesion to a urethane-based primer layer even in a humid and hot environment, and also has excellent light-resistant adhesion to a urethane-based primer layer.It can also form a film that is resistant to loss of transparency even in a humid and hot environment and has 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): Component (A): an oligomer, (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; The oligomer contains at least a component (D): an acrylic compound having a biphenyl moiety. The oligomer has a main chain with a phenol novolac structure and at least one acryloyl group.

[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), (C), and (D), and can form a film that exhibits excellent adhesion to a urethane-based primer layer even in a humid and hot environment and also exhibits excellent light-resistant adhesion to the urethane-based primer layer. Furthermore, the coating agent of the present invention is capable of forming a film that is less likely to lose transparency even in a humid and hot environment and that can have a high refractive index. Therefore, a film formed from the coating agent of the present invention maintains high adhesion to a urethane-based primer layer even in a humid and hot environment, and also maintains high adhesion to a urethane-based primer layer even in an outdoor exposure environment, while also maintaining high transparency even in a humid and hot environment.

[0015] Component (A) Component (A) is an oligomer whose main chain has a phenol novolac structure and has at least one acryloyl group. By including component (A) in the coating agent, the film obtained from the coating agent has excellent adhesion to the urethane primer layer even in a humid and hot environment, and its transparency is not easily reduced even in a humid and hot environment.

[0016] The main chain of the oligomer has a phenol novolac structure, i.e., a repeating unit in which a phenol moiety is bonded to each end of a methylene group. The phenol moiety may be phenol, or may have a structure in which the hydrogen atom of the phenol hydroxyl group is substituted with another substituent (e.g., an epoxy acrylate moiety, as described below). All of the phenol moieties contained in the oligomer may have a structure in which the hydrogen atom of the phenol hydroxyl group is substituted with another substituent (e.g., an epoxy acrylate moiety, as described below).

[0017] In the phenol novolac structure, at least one hydrogen atom of the benzene ring in the phenol moiety 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.

[0018] The oligomer has at least one acryloyl group. In this specification, the term "acryloyl group" encompasses not only an acryloyl group but also a methacryloyl group.

[0019] In the oligomer, the acryloyl group can be bonded directly or indirectly to the terminal of the oligomer, or to a side chain of the oligomer, or to both the terminal and the side chain. Here, "bonded to a side chain of the oligomer" can mean, for example, bonding to an oxygen atom of a phenolic hydroxyl group in the phenol novolac structure (i.e., substituting a hydrogen atom of the phenolic hydroxyl group). Furthermore, "bonded to the terminal of the oligomer" can mean, for example, bonding to an oxygen atom of a phenolic hydroxyl group at the terminal (main chain terminal) of the phenol novolac structure (i.e., substituting a hydrogen atom of the phenolic hydroxyl group).

[0020] The acryloyl group can be bonded to the side chain of the oligomer via another group (i.e., the acryloyl group can be indirectly bonded to the side chain of the oligomer), or it can be bonded directly to the side chain of the oligomer without any other group. Similarly, the acryloyl group can be bonded to the end of the oligomer via another group, or it can be bonded to the end of the oligomer directly without any other group. Therefore, the acryloyl group can be bonded directly to the oxygen atom of the phenolic hydroxyl group in the phenol novolac structure, or it can be bonded to the oxygen atom of the phenolic hydroxyl group via another group. Thus, the acryloyl group can be part of the phenol moiety described above.

[0021] Examples of the other groups include groups derived from an epoxy group or a glycidyl group. The groups derived from an epoxy group or a glycidyl group include, for example, groups 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 of the oligomer, the resulting coating tends to have an appropriate hardness and tends to have excellent adhesion to a urethane-based primer layer even in a humid and hot environment.

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

[0023] The oligomer preferably has two or more acryloyl groups. In this case, the strength of the resulting coating is likely to be increased. In the oligomer, the content of acryloyl groups is preferably 20 mol% or more, more preferably 50 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more, relative to the total number of moles of phenol-derived groups in the phenol novolac structure. The acryloyl groups may be directly or indirectly bonded to all of the phenol-derived oxygen atoms in the phenol novolac structure.

[0024] A specific example of an oligomer having a main chain with a phenol novolac structure is a compound represented by the following general formula (3).

[0025] [ka]

[0026] In formula (3), n is the average number of repeats, and the multiple R's may be the same or different and represent a hydrogen atom or an acryloyl moiety, with at least one of the R's being an acryloyl moiety. In formula (3), all of the R's may be acryloyl moieties. The "-Ph-OR" moiety in formula (3) (Ph represents C6H3 or C6H4) corresponds to the phenol moiety.

[0027] In the formula (3), n is a positive number, and is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, even more preferably 3 or less, and particularly preferably 2 or less. n may be 0 or 1 or more.

[0028] In the formula (3), the methylene group that connects the phenol-derived benzene rings is bonded, for example, at the ortho position relative to the —OR group.

[0029] When R is an acryloyl moiety, the acryloyl moiety is a substituent having at least an acryloyl group. Therefore, R in the formula (3) is, for example, CH2=CHCOO-R 1 - where R 1 For example, R may be a divalent group represented by the formula (1) or a divalent group represented by the formula (2). That is, R in the formula (3) may be an epoxy acrylate moiety. 1 When is a divalent group represented by the formula (2), either of the two terminals of the divalent group may be bonded to an acryloyl group.

[0030] The coating agent of the present invention may contain one type of component (A) alone, or may contain two or more types.

[0031] The weight average molecular weight of the oligomer is preferably 500 to 2500, more preferably 1000 to 2000. The molecular weight based on the molar mass of the oligomer is also preferably 500 to 2500, more preferably 500 to 2000.

[0032] The hydroxyl value (mgKOH / g) of the oligomer is preferably from 200 to 270 mgKOH / g, more preferably from 220 to 250 mgKOH / g. The hydroxyl value is measured in accordance with Method A of JIS K1557-1:2007.

[0033] The method for producing the oligomer (A) is not particularly limited, and a wide variety of known production methods can be used. For example, the oligomer (A) can be produced by reacting a compound having a phenol novolac structure with an acrylic compound such as acrylic acid in the presence of a catalyst. Examples of the catalyst include tetrabutylammonium bromide.

[0034] Examples of the compound having the phenol novolac structure include phenol novolac epoxy resins, such as the jER (registered trademark) series manufactured by Mitsubishi Chemical Corporation, specifically jER152 and jER154.

[0035] (B) Component Component (B) is an aromatic urethane acrylate. If the coating agent of the present invention does not contain component (B), adhesion to a urethane-based primer layer in a humid and hot environment 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] It is preferable that the aromatic urethane acrylate does not have a biphenyl moiety.

[0040] The molecular weight of the aromatic urethane acrylate (molecular weight based on molar mass) is preferably 1,000 to 1,500, for example.

[0041] 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.

[0042] Examples of alcohol compounds having an aromatic moiety include compounds having the same structure as the 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.

[0043] [ka]

[0044] 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.

[0045] 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.

[0046] The aromatic urethane acrylate can be obtained from a commercial product, for example, the aromatic urethane acrylate "EBECRYL" manufactured by Daicel Allnex.

[0047] The coating agent of the present invention may contain one type of component (B) alone, or may contain two or more types.

[0048] (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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] (D) Component Component (D) is an acrylic compound having a biphenyl moiety in the molecule. The acrylic compound having a biphenyl moiety can have one or more acryloyl groups in the molecule. The acryloyl group includes not only acryloyl groups but also methacryloyl groups.

[0053] In component (D), the biphenyl moiety can be, for example, a group formed by removing at least one hydrogen atom from each benzene ring of biphenyl. Such a biphenyl moiety can be a monovalent group, or a divalent, trivalent, or higher valent group. When the biphenyl moiety is a monovalent group, it is represented by "CH-CH-". A divalent group represented by "-CH-CH-" is, for example, a group formed by removing hydrogen atoms from the para positions of both benzene rings.

[0054] The biphenyl moiety is preferably a monovalent group represented by "C6H5-C6H4-" or a divalent group represented by "-C6H4-C6H4-".

[0055] 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.

[0056] In 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.

[0057] There are no particular limitations on the structure of component (D), so long as it has at least one biphenyl moiety and at least one acryloyl group in the molecule.

[0058] An example of component (D) is an alkylene glycol (meth)acrylate having a biphenyl moiety, which is represented by the following general formula (5-1):

[0059] [ka]

[0060] In the formula (5-1), R a is an alkylene group having 1 to 5 carbon atoms, and p is the average number of repetitions. a can be a methylene group, an ethylene group, or a propylene group, and is preferably an ethylene group.

[0061] In the formula (5-1), p is a positive number, and is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, even more preferably 3 or less, and particularly preferably 2 or less. p may be 0.5 or more, or may be 1 or more.

[0062] Other examples of component (D) include polyfunctional acrylates having a biphenyl moiety. That is, acrylic compounds having a biphenyl moiety and two or more acryloyl groups can also be used as component (D). Examples of such acrylic compounds include bifunctional acrylic compounds represented by the following general formula (5-2):

[0063] [ka]

[0064] Another example of component (D) is an epoxy acrylate having a biphenyl moiety (hereinafter simply referred to as "epoxy acrylate"). 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.

[0065] The epoxy acrylate has a biphenyl moiety and a group derived from an epoxy group or a glycidyl group. The number of groups derived from an epoxy group or a glycidyl group in the epoxy acrylate molecule is preferably 2 or more, and preferably 4 or less, more preferably 3 or less, and particularly preferably 2. The group derived from an epoxy group or a glycidyl group is, for example, a divalent group represented by the formula (1) or a divalent group represented by the formula (2). By having a group derived from an epoxy group or a glycidyl group in the epoxy acrylate molecule, the resulting coating tends to have an appropriate hardness and excellent weather-resistant adhesion to a urethane primer layer.

[0066] The epoxy acrylate has at least one acryloyl group in the molecule, and preferably has two or more acryloyl groups in the molecule. This makes it easier for the resulting coating to have appropriate hardness and excellent weather-resistant adhesion to the urethane primer layer. The epoxy acrylate more preferably has four or less acryloyl groups in the molecule, even more preferably three or less, and particularly preferably two.

[0067] The acryloyl group is preferably bonded to both ends of the epoxy acrylate molecule by a covalent bond. The acryloyl group can be directly bonded to the group derived from the epoxy group or glycidyl group, for example, the oxygen atom of the acryloyl group can be directly bonded to the group represented by formula (1) or (2).

[0068] A specific example of the epoxy acrylate is a compound represented by the following general formula (5-3).

[0069] [ka]

[0070] Here, in formula (5-3), 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 2 Therefore, 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-).

[0071] R 1 and R 2are 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 (5-3).

[0072] In the compound represented by the formula (5-3), the biphenyl moiety is a group formed by removing one hydrogen atom from each hydroxyl group of biphenol, i.e., the biphenyl moiety is a divalent group represented by "-O-Ph-Ph-O-" (i.e., -O-C6H4-C6H4-O-).

[0073] The method for producing the epoxy acrylate is not particularly limited, and for example, a wide variety of known production methods can be employed. For example, the epoxy acrylate (component (D)) can be produced by reacting an epoxy compound with an acrylic compound such as acrylic acid in the presence of a catalyst. Examples of the epoxy compound include compounds having epoxide moieties at both ends of a biphenyl moiety, such as the biphenyl-type epoxy resin "YX4000" series manufactured by Mitsubishi Chemical Corporation. Examples of the catalyst include tetrabutylammonium bromide.

[0074] Yet another example of component (D) is an oligomer (hereinafter simply referred to as "oligomer D") whose main chain has a phenol novolac structure containing a biphenyl moiety and has at least one acryloyl group.

[0075] The main chain of the oligomer D has a phenol novolac structure having a biphenyl moiety, i.e., derived from a phenol novolac structure. The phenol novolac structure has a repeating unit in which a phenol moiety is bonded to each end of a methylene group. The phenol moiety may be phenol, or may have a structure in which the hydrogen atom of the phenol hydroxyl group is substituted with another substituent (for example, an epoxy acrylate moiety, as described below). All of the phenol moieties contained in oligomer D may have a structure in which the hydrogen atom of the phenol hydroxyl group is substituted with another substituent (for example, an epoxy acrylate moiety, as described below).

[0076] At least one hydrogen atom of the benzene ring in the phenol moiety may be substituted with another substituent, which is not particularly limited and may be, for example, a linear or branched alkyl group having about 1 to 10 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.

[0077] In the oligomer D, the biphenyl moiety may be present bonded to a main chain skeleton having a phenol novolac structure. The biphenyl moiety may be present incorporated into the skeleton having a phenol novolac structure. The biphenyl moiety may also be bonded to the end of the skeleton having a phenol novolac structure. In terms of facilitating the formation of a film having excellent weather resistance and adhesion to a urethane primer layer, it is preferable that the biphenyl moiety be present incorporated into the skeleton having a phenol novolac structure.

[0078] An example of the oligomer D is a structure in which some of the phenol moieties in the phenol novolac structure are replaced with the biphenyl moieties. In such an oligomer D, the biphenyl moiety may be present between two methylene groups in the phenol novolac structure. In this case, both ends of the biphenyl moiety may be directly covalently bonded to the two methylene groups. The phenol moieties and the biphenyl moieties may be arranged alternately with the methylene group sandwiched between them.

[0079] The oligomer D has at least one acryloyl group. In the oligomer D, the acryloyl group can be bonded directly or indirectly to a terminal of the oligomer D, or to a side chain of the oligomer D, or to both the terminal and the side chain. Here, "bonded to a side chain of the oligomer D" can mean, for example, bonding to an oxygen atom of a phenolic hydroxyl group in the phenol novolac structure (i.e., substituting a hydrogen atom of the phenolic hydroxyl group). Furthermore, "bonded to the terminal of the oligomer D" can mean, for example, bonding to an oxygen atom of a phenolic hydroxyl group at the terminal (main chain terminal) of the phenol novolac structure (i.e., substituting a hydrogen atom of the phenolic hydroxyl group).

[0080] The acryloyl group can be bonded to the side chain of oligomer D via another group (i.e., the acryloyl group can be indirectly bonded to the side chain of oligomer D), or can be bonded directly to the side chain of oligomer D without another group. Similarly, the acryloyl group can be bonded to the terminal of oligomer D via another group, or can be bonded directly to the terminal of oligomer D without another group. Therefore, the acryloyl group can be bonded directly to the oxygen atom of the phenolic hydroxyl group in the phenol novolac structure, or can be bonded to the oxygen atom of the phenolic hydroxyl group via another group. From the above, the acryloyl group can form part of the phenol moiety described above.

[0081] The other group is a divalent group represented by the formula (1) or a divalent group represented by the formula (2). When an epoxy acrylate has a group derived from an epoxy group or a glycidyl group in the molecule, the resulting coating tends to have an appropriate hardness and tends to have excellent weather-resistant adhesion to a urethane primer layer.

[0082] The oligomer D preferably has two or more acryloyl groups. In this case, the strength of the resulting coating film is likely to be increased. In the oligomer D, the content of acryloyl groups is preferably 20 mol% or more, more preferably 50 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more, relative to the total number of moles of phenol-derived groups in the phenol novolac structure. The acryloyl groups may be directly or indirectly bonded to all of the phenol-derived oxygen atoms in the phenol novolac structure.

[0083] A specific example of the oligomer D is a compound represented by the following general formula (5-4).

[0084] [ka]

[0085] In formula (5-4), k is the average number of repeats, and the multiple R's may be the same or different and represent a hydrogen atom or an acryloyl moiety, and at least one of the R's is an acryloyl moiety (i.e., the same as R in formula (3)). 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 (i.e., R 1 and R 2 (Same meanings as m and n). When m is 0, R 1 means that there is no 2 Therefore, when m and n are 0, this means that there are four hydrogen atoms in each of the benzene rings of the biphenyl moiety.

[0086] In the formula (5-4), all R may be acryloyl moieties. The terminal "RO-C6H4-" in the formula (5-4) and the "RO-C6H3" in the repeating unit correspond to the phenol moiety.

[0087] In the formula (5-4), k is a positive number, preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, even more preferably 3 or less, and particularly preferably 2 or less. k is 1 or more. The value of k is determined by the 1 For example, if the oligomer has an epoxy group, the 1 In the NMR spectrum obtained by H-NMR measurement, the value of k can be estimated from the proton peak derived from biphenyl observed around 7.6 ppm and the proton peak derived from epoxy groups observed around 3.3 ppm.

[0088] In the formula (5-4), the methylene group in the repeating structural unit is bonded, for example, at the ortho position relative to the —OR group.

[0089] In the formula (5-4), when R is an acryloyl moiety, the acryloyl moiety is a substituent having at least an acryloyl group. Therefore, R in the formula (5-4) is, for example, CH2=CHCOO-R 3 - where R 3 For example, R may be a divalent group represented by the formula (1) or a divalent group represented by the formula (2). That is, R in the formula (5-4) may be an epoxy acrylate moiety. 3 When is a divalent group represented by the formula (2), either of the two terminals of the divalent group may be bonded to an acryloyl group.

[0090] The weight average molecular weight of the oligomer D is preferably 500 to 3500, more preferably 1500 to 2500. The molecular weight based on the molar mass of the oligomer D is also preferably 500 to 2500, more preferably 1000 to 2000.

[0091] The hydroxyl value (mgKOH / g) of the oligomer D is preferably from 120 to 240 mgKOH / g, more preferably from 150 to 210 mgKOH / g. The hydroxyl value is measured in accordance with Method A of JIS K1557-1:2007.

[0092] The method for producing the oligomer D is not particularly limited, and for example, a wide variety of known production methods can be employed. For example, the oligomer D can be produced by reacting a compound having a phenol novolac structure containing a biphenyl moiety with an acrylic compound such as acrylic acid in the presence of a catalyst. Examples of the catalyst include tetrabutylammonium bromide. An example of the compound having a phenol novolac structure is a phenol novolac epoxy resin having a biphenyl moiety, such as the biphenyl novolac epoxy resin "NC-3000" manufactured by Nippon Kayaku Co., Ltd.

[0093] The coating agent of the present invention may contain one type of component (D) alone, or may contain two or more types.

[0094] coating agent The coating agent of the present invention contains components (A), (B), (C), and (D). This allows the formation of a film that exhibits excellent adhesion to a urethane primer layer even in a humid and hot environment, and also exhibits excellent light-resistant adhesion to the urethane primer layer. Furthermore, the coating agent of the present invention is capable of forming a film that is resistant to loss of transparency even in a humid and hot environment, and that can have a high refractive index.

[0095] Since each component of the coating agent of the present invention has a radically polymerizable double bond site such as an acryloyl group, it is cured by heating or active energy rays, thereby forming a film on the substrate.

[0096] In the coating agent of the present invention, the content of component (A) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, per 100 parts by mass of the total of components (A), (B), (C), and (D), in order to facilitate improved adhesion of the resulting coating to the urethane primer layer, and is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 45 parts by mass or less, and particularly preferably 40 parts by mass or less. Note that the total mass of 100 parts by mass of components (A), (B), (C), and (D) refers to the value converted into solid content, excluding volatile components such as solvents.

[0097] 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), (C), and (D), in order to improve the 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.

[0098] 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), (C), and (D), 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.

[0099] In the coating agent of the present invention, the content of component (D) 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), (C), and (D), in order to improve the adhesion and transparency of the resulting coating to the urethane primer layer, and is 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.

[0100] The coating agent of the present invention may contain components other than the components (A), (B), (C), and (D). Examples of other components include a polymerization initiator and a solvent.

[0101] Examples of the polymerization initiator include a photopolymerization initiator and a polymerization initiator using active energy rays such as ultraviolet rays.

[0102] 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.

[0103] 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).

[0104] 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.

[0105] The content of the polymerization initiator varies depending on the type thereof, 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 components (A), (B), (C), and (D).

[0106] 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.

[0107] 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.

[0108] 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), (C), and (D) and other components added as needed in predetermined amounts.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] A film formed from the coating agent of the present invention exhibits excellent adhesion to a urethane-based primer layer even in a humid and hot environment (e.g., 500 hours of humid and hot treatment at a temperature of 80°C and a humidity of 90%), is resistant to loss of transparency even in a humid and hot environment, and has a high refractive index. The optical coating agent of the present invention is suitable for use with urethane-based primers. In other words, a film formed from the coating agent (a film containing a cured product of the optical coating agent) is suitable as a film for a urethane-based primer.

[0114] Furthermore, films formed from the coating agent of the present invention exhibit excellent adhesion to urethane-based primer layers even when exposed to light, and adhesion to urethane-based primer layers 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, films formed from the coating agent of the present invention have a high refractive index. Therefore, the optical coating agent of the present invention is suitable for use with urethane-based primers. In other words, films formed from the coating agent (films containing a cured product of the optical coating agent) are suitable as films for urethane-based primers.

[0115] The haze of the film formed by the coating agent is unlikely to change even when the film is exposed to a moist and hot environment. For example, when the film is subjected to moist and heat treatment for 500 hours in an environment at a temperature of 80°C and a humidity of 90%, the change in haze before and after the moist and heat treatment can be less than 1.5 (preferably less than 1).

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] In specifying the inventions included in the present disclosure, the components (properties, structures, functions, etc.) described in the embodiments 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 in this specification. [Example]

[0121] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0122] (raw materials) In each of the Examples and Comparative Examples, the following raw materials were used to prepare the coating agents.

[0123] Component (A): Oligomer A-1 Oligomer 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 175 parts by weight of "jER152 (registered trademark)," a phenolic novolac epoxy resin manufactured by Mitsubishi Chemical Corporation, 72 parts by weight of acrylic acid, 0.25 parts by weight of 4-methoxyphenol as a polymerization inhibitor, and 1.2 parts by weight of tetrabutylammonium bromide as a catalyst. The reaction was carried out at a reaction temperature of 95 to 110 ° C until the epoxy equivalent reached 10,000 or more. 106 parts by weight of methyl ethyl ketone was added for dilution, and a solution containing oligomer A-1 (solid concentration 70% by mass) was obtained. The weight-average molecular weight of oligomer A-1 was 1200, and the hydroxyl value was 229 mg KOH / g.

[0124] Comparative oligomer a-1 Oligomer 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 205 parts by weight of "EPICLONN865 (registered trademark)" manufactured by DIC Corporation, which does not have a phenol novolac structure, 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 119 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 oligomer a-1 (solid concentration 70% by mass).

[0125] 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).

[0126] 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).

[0127] Comparative urethane acrylate b-1 Aliphatic urethane acrylate b-1 was prepared by the following method. First, 530 parts by weight of Daicel Corporation's polycaprolactone diol "Placcel 205" (registered trademark), 350 parts by weight of Daiichi Kogyo Seiyaku Co., Ltd.'s trifunctional polyether polyol "DK Polyol G-480", and 889.2 parts by weight of isophorone diisocyanate were added to a flask equipped with a thermometer, a stirrer, and a water-cooled condenser, and the mixture was allowed to react at a reaction temperature of 70 to 80 ° C until a predetermined free isocyanate content was reached. Next, 1.08 parts by weight of 4-methoxyphenol (a polymerization inhibitor) and 383.2 parts by weight of 2-hydroxyethyl acrylate were added, and the mixture was allowed to react at a reaction temperature of 70 to 80 ° C until the free isocyanate content was 0.1% or less. After that, 922 parts by weight of methyl ethyl ketone was added for dilution, and a solution containing aliphatic urethane acrylate b-1 (solids concentration 70% by mass) was obtained.

[0128] 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

[0129] Component (D): Acrylic compound D-1: A compound represented by the formula (5-1) (Ra is an ethylene group, p is 1 to 2) ("New Frontier OPPE" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) D-2: A compound represented by the formula (5-1) (Ra is an ethylene group, p is 1) ("NK Ester A-LEN-10" from Shin-Nakamura Chemical Co., Ltd.) D-3: A compound represented by the formula (5-2) (JFE Chemical Corporation "DABP") D-4: Oligomer D obtained in Production Example 1 described below D-5: Epoxy acrylate obtained in Production Example 2 described below

[0130] Comparative acrylic compound d-1: Kyoeisha Chemical's "Light Acrylate POB-A" (registered trademark) (aromatic acrylic compound without biphenyl moieties)

[0131] (Production Example 1) Oligomer D of D-4 was prepared by the following method. First, a flask equipped with a thermometer, stirrer, and water-cooled condenser was charged with 277 parts by weight of Nippon Kayaku's biphenyl novolac epoxy resin "NC-3000," 72 parts by weight of acrylic acid, 0.35 parts by weight of 4-methoxyphenol as a polymerization inhibitor, 2.6 parts by weight of tetrabutylammonium bromide as a catalyst, and 150 parts by weight of butyl acetate. The reaction was carried out at a reaction temperature of 95 to 110 °C until the epoxy equivalent reached 15,000 or more, yielding a solution containing oligomer D (solid concentration 70% by mass). The average repeat number of oligomer D (i.e., the value of k in the formula (5-4) above; number-average degree of polymerization) was 2, and the hydroxyl value was 177 mg KOH / g.

[0132] (Production Example 2) D-5 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 D-5 (solid concentration 70% by mass).

[0133] 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 20 parts by mass of oligomer A-1 as component (A), 40 parts by mass of aromatic urethane acrylate B-1 as component (B), 20 parts by mass of C-1 as component (C), and 20 parts by mass of D-1 as component (D), converted into solids. 4 parts by mass of Omnirad184 (IGM Resins BV) as a polymerization initiator and 74 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.

[0134] 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.

[0135] 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.

[0136] Example 4 A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the component (D) was changed to D-2 as shown in Table 1.

[0137] Example 5 A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that component (D) was changed to D-3 as shown in Table 1.

[0138] Example 6 A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the component (D) was changed to D-4 as shown in Table 1 and the solvent was changed to 66 parts by weight of methyl ethyl ketone.

[0139] Example 7 A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the component (D) was changed to D-5 as shown in Table 1 and the solvent was changed to 66 parts by weight of methyl ethyl ketone.

[0140] Example 8 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 oligomer A-1, the (D) component was changed to 10 parts by mass of D-1, and the solvent was changed to 70 parts by weight of methyl ethyl ketone.

[0141] Example 9 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 oligomer A-1 as component (A) was changed to 10 parts by mass, the amount of D-1 as component (D) was changed to 30 parts by mass, and the amount of methyl ethyl ketone as the solvent was changed to 79 parts by weight.

[0142] Example 10 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 40 parts by mass of oligomer A-1, the (B) component was changed to 30 parts by mass of aromatic urethane acrylate B-1, the (D) component was changed to 10 parts by mass of D-1, and the solvent was changed to 70 parts by weight of methyl ethyl ketone.

[0143] Example 11 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 40 parts by mass of oligomer A-1, the (B) component was changed to 10 parts by mass of aromatic urethane acrylate B-1, the (D) component was changed to 30 parts by mass of D-1, and the solvent was changed to 79 parts by weight of methyl ethyl ketone.

[0144] (Comparative Example 1) A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the component (A) was changed to oligomer a-1 as shown in Table 1 and the solvent was changed to 74 parts by weight of methyl ethyl ketone.

[0145] (Comparative Example 2) A coating agent with a concentration of 50% by 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 and the solvent was changed to 74 parts by weight of methyl ethyl ketone.

[0146] (Comparative Example 3) A coating agent with a concentration of 50% by mass was obtained in the same manner as in Example 1, except that the component (D) was changed to d-1 as shown in Table 1 and the solvent was changed to 74 parts by weight of methyl ethyl ketone.

[0147] (Creation of the coating) Using the coating agents prepared in each Example and Comparative Example, a film was formed on a urethane-based 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-based primer solution was applied to the corona-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-based primer solution was prepared by mixing 36 parts by weight of Elastron H-15 (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, 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-based primer layer to a film thickness of approximately 4 to 7 μm in a dried state to form a coating. Next, a high-pressure mercury lamp at 80 W / cm was used. 2 Using an integrated illuminance of 150 mJ / cm 2The 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.

[0148] (Evaluation method) <Heat and humidity adhesion> The heat and humidity adhesion was measured based on a 2mm cross-cut test in accordance with JIS K5400-8.5:1990. Specifically, the film obtained in the "Preparation of Film" section above was subjected to heat and humidity treatment by storing it in an environment with a temperature of 80°C and a humidity of 90% for 500 hours. After this heat and humidity 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 residual rate, the adhesion under heat and humidity was evaluated according to the following criteria. ≪Judgment criteria≫ A: 100% survival rate B: Residual rate is 95% or more but less than 100% C: Residual rate is less than 95%

[0149] <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: Survival rate is 80% or more B: Residual rate is 50% or more but less than 80% C: Residual rate is less than 50%

[0150] <Haze change> The haze of the resulting film was measured using a turbidity meter (NDH4000, manufactured by Nippon Denshoku) in accordance with JIS K 7136: 2000. From this haze measurement, the amount of change in haze before and after the above-mentioned moist heat treatment was calculated, and the moist heat resistance of the haze was evaluated according to the following criteria. ≪Judgment criteria≫ A: Δ was less than 1.0, and the wet heat resistance was remarkably excellent. B: Δ was 1.0 or more and less than 2.0, and the wet heat resistance was excellent. C: Δ was 2.0 or more, and the moist heat resistance was significantly deteriorated.

[0151] <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: 1.565 or higher B: 1.555 or more and less than 1.565 C: Less than 1.555

[0152] 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 resulting films in terms of wet heat adhesion, light resistance adhesion, haze, and film refractive index. Note that blank spaces in the compounding conditions in Table 1 indicate that the raw material was not used.

[0153] As can be seen from Table 1, the coating agents obtained in the examples contain components (A), (B), (C), and (D), and therefore can form films that have excellent adhesion to urethane primer layers even in humid and hot environments and also have excellent light-resistant adhesion to urethane primer layers. It was also shown that the coating agents obtained in the examples are resistant to loss of transparency even in humid and hot environments and can maintain high transparency. It was also shown that the coating agents obtained in the examples can have a high refractive index.

[0154] [Table 1]

Claims

1. An optical coating agent used for coating a urethane-based primer layer, The following components (A), (B), (C) and (D): Component (A): an oligomer; (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; Component (D): an acrylic compound having a biphenyl moiety; Contains at least The oligomer has a main chain with a phenol novolac structure and at least one acryloyl group, and is an optical coating agent.

2. The optical coating agent according to claim 1 , wherein the oligomer has a group derived from an epoxy group or a glycidyl group.

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. 2. The optical coating agent according to claim 1, wherein the acrylic compound having a biphenyl moiety has one or more acryloyl groups in the molecule.

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

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