Curable resin composition

Abstract

The objective of this invention is to provide a curable resin composition for inkjet printing that provides a black, light-shielding coating with high light-shielding properties, good surface curing properties, stable adhesion under high temperature and humidity conditions, and high hardness after curing. The technical method involves a curable resin composition comprising (A) an epoxy compound, (B) an oxybutane compound, (C) a photoacid generator, and (D) a black colorant. The aforementioned epoxy compound comprises, in a mass ratio ranging from 5:100 to 30:100, (a) an alicyclic epoxy compound with intramolecular ester bonds and (b) an alicyclic epoxy compound without intramolecular ester bonds.

Description

[Technical Field]

[0001] This invention relates to curable resin compositions. [Previous Technology]

[0002] In the light-shielding components of displays mounted on PCs or mobile devices, high light-shielding performance is required to minimize the impact of backlight. Therefore, light-shielding inks for forming black matrices are used as materials for such light-shielding components. On the other hand, from the viewpoint of manufacturing efficiency, the technology of using inkjet printing to coat such light-shielding inks onto a substrate to manufacture light-shielding components has attracted attention. As a technology for coating inks onto an object using inkjet printing, for example, Patent Document 1 proposes a technology for using an active energy line-curing ink comprising a photocationic polymerization initiator, a polyfunctional epoxy compound, a monofunctional alicyclic epoxy compound, and an oxobutane compound for inkjet recording. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2010-106254 [Summary of the Invention]

[0004] [The problem that the invention aims to solve]

[0005] Here, especially for smartphones and smartwatches, it is naturally assumed that they will be used in various environments such as summer and inside a car, in addition to being used at room temperature. Therefore, it is expected that the light-blocking ink used will have high reliability. For example, not to mention high light-blocking properties, the light-blocking ink also needs to maintain high adhesion to the substrate even under high temperature and high humidity, good curing properties, and high hardness of the hardened coating film formed after curing.

[0006] However, typically, light-shielding inks contain a high concentration of pigments for light-shielding purposes, resulting in a high OD value. Therefore, if an inkjet printing method is used to coat the light-shielding ink onto a substrate, the light used to light-cure the coating formed on the substrate will inevitably have difficulty reaching the bottom of the coating. As a result, the overall curing properties of the coating are insufficient, leading to reduced hardness of the cured coating itself and decreased adhesion to substrates such as glass or metal.

[0007] Regarding this point, in the active energy line curing ink proposed in Patent Document 1, although an alicyclic epoxy compound with intramolecular ester bonds is used, it is estimated that light will not be able to reach the bottom of the coating sufficiently when the pigment concentration is increased. Therefore, the curing property of the coating is insufficient, and it is difficult to maintain the adhesion of the cured coating to the substrate when placed under high temperature and high humidity conditions. Furthermore, the hardness of the cured coating after the ink is cured is not expected to meet the required level.

[0008] Therefore, in view of the above, the object of the present invention is to provide a curable resin composition that provides a cured coating film that, in addition to high light-blocking properties, exhibits good surface curing properties, maintains stable adhesion under high temperature and humidity conditions, and also has high hardness after curing. [Means for Solving the Problem]

[0009] As a result of the inventors' efforts, the above-mentioned problem was solved by using a curable resin composition that contains two epoxy compounds with their own structural characteristics in a specific numerical range of mass ratio, and further contains an oxybutane compound, a photoacid generator, and a black colorant, thus completing the present invention. More specifically, the problem is solved by the following: A curable resin composition comprising (A) an epoxy compound, (B) an oxybutane compound, (C) a photoacid generator, and (D) a black colorant, wherein the aforementioned (A) epoxy compound contains (a) an alicyclic epoxy compound having intramolecular ester bonds and (b) an alicyclic epoxy compound not having intramolecular ester bonds in a mass ratio ranging from 5:100 to 30:100.

[0010] The curable resin composition of the present invention is applicable to inkjet printing methods. In this case, it is more preferably, from the viewpoint of smooth ejection from the inkjet nozzle, that its viscosity is in the range of 5 to 20 mPa·s at 50°C, and more preferably in the range of 5 to 15 mPa·s at 50°C. The viscosity can be measured using, for example, a cone-plate viscometer (TVE-33H manufactured by Toki Sangyo Co., Ltd.).

[0011] A more preferred embodiment relates to a curable resin composition, wherein the aforementioned (b) alicyclic epoxy compound without ester bonds in the molecule has a difunctional epoxy group.

[0012] Another preferred embodiment relates to a curable resin composition, wherein the aforementioned (D) black colorant is carbon black, and comprises 5 or more parts by mass relative to the total of 100 parts by mass of the aforementioned (A) epoxy compound and (B) cyclobutane compound.

[0013] Another preferred embodiment relates to a curable resin composition, wherein the mass ratio of the aforementioned (B) oxycyclobutane compound to the aforementioned (A) epoxy compound is in the range of 2:100 to 40:100.

[0014] Another preferred embodiment relates to a curable resin composition, wherein the aforementioned epoxy compound (A) comprises (a) an alicyclic epoxy compound having intramolecular ester bonds and (b) an alicyclic epoxy compound without intramolecular ester bonds in a mass ratio ranging from 8:100 to 25:100. By specifying the ratio of the amount of the alicyclic epoxy compound having intramolecular ester bonds in (a) within the above range, a cured coating film with excellent adhesion can be produced even after being placed under high temperature and high humidity conditions. By setting the amount of the alicyclic epoxy compound having intramolecular ester bonds in (a) at or above the lower limit of the above mass ratio, it is envisioned that the flexibility of the coating film can be appropriately maintained by the hydrolysis of ester bonds, the internal stress of the coating film can be suppressed, and the initial adhesion can be improved. Furthermore, by setting the amount of alicyclic epoxy compounds with ester bonds in (a) molecules to below the upper limit of the above mass ratio, it is envisioned that the deterioration of the coating film caused by hydrolysis after being placed under high temperature and high humidity conditions can be suppressed, and the photocured coating film properties such as adhesion can be maintained.

[0015] Another preferred embodiment relates to a curable resin composition, wherein the mass ratio of the aforementioned (B) oxybutane compound to the aforementioned (A) epoxy compound is in the range of 10:100 to 20:100. By specifying the ratio of the (B) oxybutane compound in the above range, the curability of the coating surface and the substrate can be improved evenly. By setting the above ratio of the amount of the compound to the lower limit or above, the tackiness of the cured coating after light curing becomes good. Furthermore, by setting the above ratio of the amount of the compound to the upper limit or below, the crosslinking density of the cured coating can be appropriately maintained, flexibility can be maintained, pencil hardness can be improved, and adhesion after being placed under high temperature and high humidity conditions can be improved.

[0016] Another preferred embodiment also relates to a curable resin composition, which further includes an alkoxyanthracene derivative as a photosensitizer.

[0017] Since the curable resin composition of the present invention is suitable for use as a black light-blocking agent in smartphones, etc., a more preferred state is that the OD value of the cured coating film with a thickness of 10-20 μm is preferably 4 or higher, and more preferably 5 or higher. The OD value can be calculated based on the formula OD value = -log10(T / 100) by measuring the amount of transmitted light using, for example, a transmittance meter (model: X-Rite 361T; light source wavelength 400-800 nm; manufactured by Sakata Inx Engineering Co., Ltd.). [Effects of the Invention]

[0018] The curable resin composition of the present invention, having the above-described structure, has the advantages of forming a cured coating film that not only has high light-shielding properties and good surface curing properties, but also exhibits stable adhesion and high hardness even under high temperature and high humidity conditions. Furthermore, the curable resin composition of the present invention is also suitable for inkjet applications and has the advantage of good manufacturing efficiency in the manufacture of various displays. Moreover, due to the above-described characteristics, the curable resin composition of the present invention is also expected to be particularly suitable for use as a black light-shielding material for displays.

Implementation Method

[0019] [(A) Epoxy compounds]

[0020] The curable resin composition of the present invention contains (A) an epoxy compound in order to improve the hardness of the formed cured product (cured coating). In particular, the curable resin composition of the present invention, in order to improve adhesion to the substrate even when exposed to harsh environments with higher temperatures and humidity, uses two types of epoxy compounds as the aforementioned (A) epoxy compound: (a) an alicyclic epoxy compound having ester bonds in its molecule, and (b) an alicyclic epoxy compound not having ester bonds in its molecule.

[0021] When using epoxy compounds in curable resin compositions with high OD values, alicyclic epoxy compounds are typically used as one of the components due to their high reactivity. In particular, from the viewpoint of improving the surface curing or curing properties of the curable resin composition, alicyclic epoxy compounds with ester bonds are conventionally used. However, even curable resin compositions containing alicyclic epoxy compounds with such ester bonds have the disadvantage of insufficient adhesion to the substrate when used in displays for smartphones and other devices exposed to harsh environments with higher temperatures and humidity.

[0022] Therefore, in this invention, two epoxy compounds are used as epoxy compound (A): an alicyclic epoxy compound with ester bonds in its molecule (a) and an alicyclic epoxy compound without ester bonds in its molecule (b). Furthermore, by including these two epoxy compounds in the curing resin composition at a mass ratio in the range of 5:100 to 30:100, preferably 8:100 to 25:100, the aforementioned disadvantages can be avoided. By specifying the ratio of the alicyclic epoxy compound with ester bonds in its molecule (a) within the above range, the deterioration caused by ester hydrolysis in the photocured coating can be suppressed, and the coating exhibits both flexibility and curability, resulting in excellent adhesion.

[0023] Hereinafter, we will describe the use of an alicyclic epoxy compound containing (a) an ester bond in the molecule of (A) an epoxy compound and an alicyclic epoxy compound not containing an ester bond in the molecule of (b) an epoxy compound that is a component of the curable resin composition of the present invention.

[0024] [(a) Alicyclic epoxides with intramolecular ester bonds] In this invention, an alicyclic epoxide refers to a compound having one or more aliphatic ring structures within its molecule, wherein two carbon atoms in the aliphatic ring further form a ring with oxygen atoms to form an epoxy group. Furthermore, (a) an alicyclic epoxide with intramolecular ester bonds refers to the aforementioned alicyclic epoxide compound having ester bonds in its chemical structure.

[0025] As an alicyclic epoxy compound having an ester bond within the molecule of this (a), it is preferable to list compounds having the following structures, for example: (where n1 represents an integer from 1 to 30) (where A represents an alkyl group with 1 to 8 carbon atoms; n2 represents an integer from 1 to 30)

[0026] As an alicyclic epoxy compound having an ester bond within the molecule (a), commercially available products can certainly be used, preferably such as CELLOXIDE 2021P or CELLOXIDE 2081 (both manufactured by Daicel).

[0027] (a) Alicyclic epoxy compounds with ester bonds in the molecule can be used alone or in combination of two or more.

[0028] [(b) Alicyclic epoxides without intramolecular ester bonds] In this invention, (b) alicyclic epoxides without intramolecular ester bonds refer to alicyclic epoxides described in the above-mentioned (a) alicyclic epoxides with intramolecular ester bonds that do not have intramolecular ester bonds, such as alicyclic epoxides with ether bonds replacing ester bonds. Examples of alicyclic epoxides without intramolecular ester bonds (b) include compounds having the following structures:

[0029] As for (b) alicyclic epoxy compounds that do not have ester bonds in the molecule, commercially available products can certainly be used. Examples of such products include limonene dioxide (LDO) (manufactured by SYMRISE), THI-DE, DE-102 and DE-103 (manufactured by JXTG Energy), X-40-2678 and X-40-2669 (manufactured by Shin-Etsu Chemical Co., Ltd.), EHPE-3150 and CELLOXIDE 2000 (manufactured by Daicel), and KR-470 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0030] Furthermore, among the alicyclic epoxy compounds (b) that do not have ester bonds within the molecule, those having difunctional epoxy groups are preferred in this invention. Such a difunctional alicyclic epoxy compound (b) that does not have ester bonds within the molecule is a compound having a total of two alkyl oxyoxides represented by the following structural formulas: and / or cyclohexyl oxyoxides represented by the following structural formulas. Examples of commercially available products include, for instance, THI-DE, DE-102 and DE-103 (manufactured by JXTG Energy Corporation), X-40-2678 and X-40-2669 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0031] (b) Alicyclic epoxy compounds that do not have ester bonds in the molecule can be used alone or in combination of two or more.

[0032] From the viewpoint of curability and tack, the total content of (a) alicyclic epoxy compounds having ester bonds in the curable resin composition of the present invention is preferably 3 to 60 parts by mass, and more preferably 3 to 30 parts by mass, relative to a total of 100 parts by mass of (A) epoxy compound and (B) oxobutane compound. Furthermore, from the viewpoint of adhesion to the substrate, the total content of (b) alicyclic epoxy compounds not having ester bonds is preferably 30 to 90 parts by mass, and more preferably 40 to 80 parts by mass, relative to a total of 100 parts by mass of (A) epoxy compound and (B) oxobutane compound. However, the respective contents of these two alicyclic epoxy compounds (a) and (b) need to be adjusted to a ratio within the specific numerical range mentioned above.

[0033] [Other Epoxy Compounds] In addition to the alicyclic epoxy compounds with ester bonds in the molecule (a) and the alicyclic epoxy compounds without ester bonds in the molecule described above, the curable resin composition of the present invention may further include epoxy compounds other than (a) and (b), such as non-alicyclic epoxy compounds, as other epoxy compounds, in order to further improve the properties of the curable resin composition of the present invention or to impart new properties. Since conventionally available other epoxy compounds that can be used in the present invention are sufficient, they cannot all be listed here. If preferred examples are listed, Denacol EX-212 and Denacol EX-121 (both manufactured by Denacol Corporation), and KBM-403 (manufactured by Shin-Etsu Silicone Corporation), etc. The total content of such other epoxy compounds is preferably 130 parts by mass, and more preferably 3 to 20 parts by mass, relative to a total of 100 parts by mass of (A) epoxy compounds (including epoxy compounds of (a) and (b) and other epoxy compounds) and (B) oxobutane compounds.

[0034] [(B)Oxycyclobutane compound] In the curable resin composition of the present invention, from the viewpoint of improving the hardness of the cured product, it contains a (B)oxycyclobutane compound as a thermosetting resin. However, in the present invention, the content of the (B)oxycyclobutane compound can be adjusted to a mass ratio within a specific numerical range relative to the total amount of the (A) epoxy compound, that is, the total amount of (a) alicyclic epoxy compounds having ester bonds in the molecule, (b) alicyclic epoxy compounds not having ester bonds in the molecule, and other epoxy compounds. Specifically, the content of the (B)oxycyclobutane compound can be adjusted such that the mass ratio of the (B)oxycyclobutane compound to the (A) epoxy compound is in the range of 2:100 to 40:100, preferably in the range of 10:100 to 20:100.

[0035] As such (B)oxobutane compounds, they are not limited to monofunctional ones, but can also be polyfunctional ones. Examples of monofunctional (B)oxobutane compounds include, for example, 3-methyloxobutane, 3-ethyloxobutane, 3-hydroxymethyloxobutane, 3-methyl-3-hydroxymethyloxobutane, 3-ethyl-3-hydroxymethyloxobutane, etc.

[0036] Furthermore, examples of multifunctional (B)oxobutane compounds include bis[(3-methyl-3-oxocyclobutylmethoxy)methyl] ether, bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxocyclobutylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]benzene, (3-methyl-3-oxocyclobutyl)methyl acrylate, and propylene. In addition to polyfunctional oxybutanes such as methyl 3-ethyl-3-oxocyclobutane, methyl methacrylate, methyl 3-ethyl-3-oxocyclobutane, and their oligomers or copolymers, etherifications of oxybutanols with phenolic resins, poly(p-hydroxystyrene), Cardo-type bisphenols, calixarenes, resorcinol calixarenes, or etherifications with hydroxyl-containing resins such as sesquioxanes are also included. Other examples include copolymers of unsaturated monomers with oxybutane rings and alkyl (meth)acrylates.

[0037] Commercially available products can certainly be used as (B) cyclobutane compounds. For example, preferred are OXT-101, OXT-121, OXT-212 and OXT-221 (manufactured by Toa Synthetic Co., Ltd.).

[0038] The curable resin composition of the present invention may contain one or more of the above-mentioned (B) oxybutane compounds alone or of course two or more.

[0039] From the viewpoint of the hardness of the cured product, the content of this (B) oxybutane compound is preferably 3 to 40 parts by mass, and more preferably 8 to 30 parts by mass, relative to 100 parts by mass of the total (A) epoxy compound and (B) oxybutane compound. However, the content of the (B) oxybutane compound needs to be adjusted so that the mass ratio to the mass of the (A) epoxy compound contained therein is within the specific numerical range described above. The total blending amount of the (A) epoxy compound and (B) oxybutane compound, based on the mass of the curable resin composition of the present invention, is preferably 25 to 95% by mass, and more preferably 35 to 90% by mass.

[0040] [(C) Photoacid Generator] The curable resin composition of the present invention contains a (C) photoacid generator, which is a compound capable of undergoing cationic polymerization initiated by ultraviolet irradiation. Examples of (C) photoacid generators include diazonium salts, iodonium salts, bromium salts, chlorodonium salts, strontium salts, selenonium salts, pyranium salts, thiaranium salts, pyridinium salts, and other ononium salts; halogenated compounds such as trihalomethanes (trihalomethyl)-S-triazine and its derivatives; 2-nitrobenzyl esters of sulfonic acids; iminosulfonates; 1-sideoxy-2-diazonaphthoquinone-4-sulfonate derivatives; N-hydroxyimidosulfonates; tris(methanesulfonyloxy)benzene derivatives; disulfonyldiazomethanes; sulfonylcarbonylalkanes; sulfonylcarbonyldiazomethanes; disulfonium compounds, etc. This type of (C) photoacid generator can be used alone or in combination of two or more.

[0041] Commercially available products can be used as (C) photoacid generating agents, such as CPI-100P, CPI-200K, CPI-101A (or higher, manufactured by San-Apro), CYRACURE photocuring initiator UVI-6990, CYRACURE photocuring initiator UVI-6992, CYRACURE photocuring initiator UVI-6976 (or higher, manufactured by Dow Chemical Japan), ADEKA OPTOMER SP-150, ADEKA OPTOMER SP-152, ADEKA OPTOMER SP-170, ADEKA OPTOMER SP-172 (or higher, manufactured by Asahi Denka Kogyo), CI-5102, CI-2855 (or higher, manufactured by Nippon Soda), San-Aid SI-60L, San-Aid SI-80L, San-Aid SI-100L, San-Aid SI-110L, San-Aid... SI-180L, San-Aid SI-110, San-Aid SI-145, San-Aid SI-150, San-Aid SI-160, San-Aid SI-180 (all manufactured by Sanshin Chemical Industry Co., Ltd.), ESACURE 1064, ESACURE 1187 (all manufactured by Lamberti Co., Ltd.), Omnicat 432, Omnicat 440, Omnicat 445, Omnicat 550, Omnicat 650, Omnicat BL-550, Omnicat 250 (manufactured by IGM Resin Co., Ltd.), RHODORSIL PHOTOINITIATOR 2074 (manufactured by Rhodia Japan Co., Ltd.), WPI-113, WPI-116, WPI-169, WPI-170 (manufactured by Wako Pure Chemical Industries Co., Ltd.), etc.

[0042] Among these, CPI-100P, CPI-101A, CPI-200K, CPI-210S, or aromatic iodonium salts such as Omnicat 250, WPI-113, WPI-116, WPI-169 and WPI-170 are preferred.

[0043] The content of (C) photoacid generator in the curable resin composition is preferably 5 to 30 parts by mass relative to 100 parts by mass of the total of (A) epoxy compound and (B) cyclobutane compound, and more preferably 7 to 15 parts by mass.

[0044] [(D) Black Colorant] The curable resin composition of the present invention preferably contains a (D) black colorant, particularly a black pigment, from the viewpoint of use as a black opaque material. Typically, black pigments such as carbon black are preferred, but black dyes or colorants of other colors may also be used within the scope of the intended use, and of course, they may be included in addition to carbon black.

[0045] In addition to carbon black, inorganic pigments such as iron(III) oxide (Fe3O4), titanium dioxide, copper manganese black, copper chromium black and cobalt black, as well as organic pigments such as indigo black and aniline black, can be listed as black pigments.

[0046] Furthermore, as coloring agents with other colors, well-known and commonly used red, blue, green, and yellow pigments or dyes can be listed.

[0047] The amount of black colorant (D) in the curable resin composition of the present invention is adjusted in consideration of the intended use of the cured product. From the viewpoint of balancing the curability and adhesion of the coating film, it is preferably 5 parts by mass or more, and more preferably 5 parts by mass or more and 15 parts by mass or less, relative to a total of 100 parts by mass of (A) epoxy compound and (B) cyclobutane compound.

[0048] [Photosensor] To further enhance photosensitivity, the curable resin composition of the present invention preferably further contains a photosensor. This photosensor is preferably a compound that becomes excited by light with a wavelength of 350 nm to 450 nm. Examples include, for instance, polynuclear aromatic compounds such as pyrene, perylene, triphenylene, and anthracene; xanthene compounds such as fluorescein, eosin, erythrosine, rhodamine B, and rose Bengal; xanthone compounds such as thioxanthone, dimethylthioxanthone, and diethylthioxanthone; anthocyanins such as thiacarbocyanine and oxacarbocyanine; and anthocyanins such as merocyanine and carbomerocyanine; and complex compounds. Anthocyanins; oxonols; thionins, methylene blue, toluidine blue, and other thiazides; acridines, such as acridine orange, chloroflavin, and acriflavine; acridine ketones, such as 10-butyl-2-chloroacridone; anthraquinones; squaryliums; styrene compounds; basic styrene compounds; coumarins, such as 7-diethylamino-4-methylcoumarin. Among these, anthracene compounds, especially alkoxyanthracene derivatives, are preferred. These photosensitizers can, of course, be used in combination with two or more of these compounds.

[0049] Commercially available products can also be used as photosensitizers. Examples of such products include ANTHRACURE (registered trademark) UVS-1101 (diethoxyanthracene; manufactured by Kawasaki Chemical Industry Co., Ltd.), ANTHRACURE (registered trademark) UVS-1221 (diepropoxyanthracene; manufactured by Kawasaki Chemical Industry Co., Ltd.), and ANTHRACURE (registered trademark) UVS-1331 (diebutoxyanthracene; manufactured by Kawasaki Chemical Industry Co., Ltd.), as well as alkoxyanthracene derivatives.

[0050] The content of the photosensitizer is 0.1 to 2.0 parts by weight relative to 1 part by weight of the above-mentioned photoacid generator, preferably 0.2 to 1.0 parts by weight.

[0051] [Other Components] Furthermore, the curable resin composition of the present invention may further contain other components such as solvents, reactive diluents, dispersants, tackifiers, surfactants, antioxidants, plasticizers, flame retardants, antistatic agents, leveling agents, defoamers, and antibacterial agents, without impairing its properties. As a reactive diluent capable of reducing the viscosity of the curable resin composition of the present invention, a photoreactive diluent is preferred. Examples of photoreactive diluents include (meth)acrylates, vinyl ethers, ethylene derivatives, styrene, chloromethylstyrene, α-methylstyrene, maleic anhydride, dicyclopentadiene, N-vinylpyrrolidone, N-vinylmethylamine, dimethyldioxane, oxobutanol, 3-ethyl-3-(phenoxymethyl)oxobutanol, resorcinol diglycidyl ether, and compounds having unsaturated double bonds, oxobutyl groups, etc. Among these, (meth)acrylates are preferred.

[0052] [Curing Material and Manufacturing Method Thereof] The curable resin composition of the present invention is applied to a target location on a substrate by inkjet printing, and then cured to form a cured material. As an inkjet printing method, a piezoelectric method is preferred, but not particularly limited. Suitable wavelengths include those in the ultraviolet region such as 365nm, 385nm, 395nm, and 405nm, but not particularly limited. Curing can be performed by irradiating the applied composition with an active energy beam. Suitable irradiation sources for the active energy beam include LEDs, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, and metal halide lamps. Other sources such as electron beams, alpha rays, beta rays, gamma rays, X-rays, and neutron beams can also be used. Furthermore, one or more irradiation sources can be used; in the case of two or more, light sources of different wavelengths can naturally be combined.

[0053] Furthermore, the exposure amount of the active energy line is usually in the range of 10~10000mJ / cm2, preferably 20~2000mJ / cm2, and even more preferably 100~2000mJ / cm2.

[0054] Hereinafter, embodiments and comparative examples are shown to specifically describe the present invention, but the present invention is not limited to the following embodiments. Furthermore, unless otherwise stated, "parts" and "%" shown are based on mass. [Examples]

[0055] Each component was mixed separately according to the mixing amounts recorded in Table 1 below, and pre-mixed in a mixer to prepare the curable resin compositions of Examples 1-10 and Comparative Examples 1-4. Unless otherwise specified, the mixing amounts in the table represent parts by mass.

[0056] ※The components corresponding to each number in Table 1 are as follows. 1)(a) Alicyclic epoxy compounds with intramolecular ester bonds: CELLOXIDE 2021P (manufactured by Daicel) Chemical name: 3,4-epoxycyclohexylmethyl (3,4-epoxy)cyclohexane carboxylate 2)(a) Alicyclic epoxy compounds with intramolecular ester bonds: CELLOXIDE 2081 (manufactured by Daicel) Chemical name: ε-caprolactone-modified 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexane carboxylate 3)(b) Alicyclic epoxy compounds without intramolecular ester bonds: LDO (manufactured by SYMRISE) Chemical name: limonene dioxide 4)(b) Alicyclic epoxy compounds without intramolecular ester bonds: THI-DE (manufactured by JXTG Energy) Chemical name: tetrahydroindene diepoxide 5) Other epoxy compounds: Denacol EX-212 (Nagase (Made by ChemteX) Chemical name: 1,6-hexanediol diglycidyl ether 6) Other epoxy compounds: Denacol EX-121 (Made by Nagase ChemteX) Chemical name: 2-ethylhexyl glycidyl ether 7) Other epoxy compounds: KBM-403 (Made by Shin-Etsu Chemical Co.) Silicon coupling agent with epoxy group as organic functional group, chemical name: 3-epoxypropoxypropyltrimethoxysilane 8) (B) Monofunctional cyclobutane compound: OXT-212 (Made by Dong-A Synthetic Co.) Chemical name: 2-ethylhexyl cyclobutane 9) (B) Difunctional cyclobutane compound: OXT-221 (Made by Dong-A Synthetic Co.) Chemical name: 3-ethyl-3{[(3-ethylcyclobutane-3-yl)methoxy]methyl}cyclobutane 10) Photosensitive agent: ANTHRACURE UVS-1331 (manufactured by Kawasaki Chemical Industry Co., Ltd.) Chemical name: 9,10-dibutoxyanthracene 11)(C) Photoacid generator: CPI-100P (50% solids) (manufactured by San-Apro Co., Ltd.) Chemical name: diphenyl[4-(phenylhydrothio)phenyl]silane-hexafluoro-λ5-phosphate 12)(C) Photoacid generator: Omnicat 250 (manufactured by IGM resin Co., Ltd.) Chemical name: 4-isobutylphenyl(4-methylphenyl)iodonium hexafluorophosphate (75% solids) 13)(D) Black colorant: Pigment black 7 (carbon black)

[0057] Cured products (cured coatings) with a film thickness of 5 μm were obtained from the curable resin compositions of Examples 1-10 and Comparative Examples 1-4. As described below, the cross-cutting ability, pencil hardness, and touch dryness after UV curing of the cured products were measured. The viscosity of the curable resin compositions of Examples 1-10 and Comparative Examples 1-4, when measured with a cone-plate viscometer (TVE-33H manufactured by Toki Sangyo Co., Ltd.) at an ink temperature of 50°C and 100 rpm, was in the range of 5-20 mPa·s for each.

[0058] [Preparation of Test Substrates] Test substrates were prepared by using an inkjet printer under the following conditions: the curable resin compositions of Examples 1-10 and Comparative Examples 1-4 were drawn onto a substrate and then cured with UV light. A glass substrate (110mm × 160mm, 1mm thickness) was used as the substrate. ・Film thickness after curing under the inkjet printer's drawing conditions: 5μm Equipment: Piezoelectric inkjet printer (using Fujifilm DMP-2831 material printer (copy head temperature 50°C)) ・UV curing conditions: LED-UV lamp (Phoseon Technology FireEdge FE400) Exposure: 1500mJ / cm² Wavelength: 365nm

[0059] [Cross Cutting] In accordance with JIS K 5600-5-6 1999, the hardened coatings on each test substrate of the hardened resin composition of Examples 1-10 and Comparative Examples 1-4 obtained in [Preparation of Test Substrates] were cut with a cross-cutting guide at 1 mm intervals to make 25 (5×5) squares with a width of 1 mm in both the longitudinal and transverse directions. Transparent adhesive tape (width 25±1 mm) was applied to the squares of the hardened coating. The tape was rubbed firmly with a finger until the hardened coating could be seen through it. The tape was left to adhere for no more than 5 minutes and then peeled off firmly at an angle of approximately 60 degrees for 0.5 to 1.0 seconds (tape peeling). The condition of the squares was then investigated. The cross-cutting was performed twice: after the hardened coating was applied, it was placed at 23°C and 50%RH for 3 hours (initial adhesion), and then placed in a constant temperature and humidity bath (Espec LHL-114) at 85°C and 85%RH for 240 hours (85°C and 85%RH adhesion). The evaluation criteria are as follows. Evaluation criteria other than "△" and "×" indicate good adhesion between the hardened coating and the test substrate, and evaluation criteria "◎" indicate particularly good adhesion. ◎: The peeled squares maintained 100% adhesion, and no defects were found. ○: The peeled squares maintained 100% adhesion, and slight defects were found at the intersections of the squares. △: The peeled squares maintained 100% adhesion, and peeling occurred at the intersections of the squares. ×: The peeled squares were not 100% adhesion. The results are shown in Table 2 below.

[0060] [Pencil Hardness] Regarding the fabrication of test substrates, the pencil hardness of the surface of the hardened coating on each test substrate of the hardened resin composition of Examples 1-10 and Comparative Examples 1-4 was measured in accordance with JIS K 5600-5-4 1999 and evaluated as follows. Evaluation criteria other than "×" indicate high hardness of the hardened coating, and judgment criteria "◎" indicate particularly high hardness. ◎: H or higher 〇: HB ×: B or lower The results are shown in Table 2 below.

[0061] [Touch Drying Properties After UV Curing (Touch Test)] The touch drying properties of the cured coatings on each test substrate of the cured resin compositions of Examples 1-10 and Comparative Examples 1-4 obtained in [Preparation of Test Substrates] were evaluated as follows. Evaluation criteria other than "×" indicate good curing properties of the cured coating surface, and evaluation criteria "◎" indicate particularly good curing properties of the cured coating surface. ◎: No traces are left even when touched with a finger. ○: A few traces are left when touched with a finger, but there are no problems in actual use. ×: It is sticky when touched with a finger, and the pigment components remain on the finger. The results are shown in Table 2 below.

[0062] [OD Value] Except for changing the cured film thickness to 10 μm or 20 μm in [Test Substrate Fabrication], the OD values ​​of the cured coatings on the test substrates of Examples 1-10 and Comparative Examples 1-4, which were prepared using the same method, were measured as follows. The glass substrate was mounted with the cured coating side facing the measuring instrument on a transmittance meter (Sakata Inx Engineering Co., Ltd., Model: X-Rite 361T, light source wavelength: 400-800 nm) to evaluate the OD value. As a result, the OD values ​​of the examples and comparative examples with a cured film thickness of 10 μm were 4 to 6, and the OD values ​​of the examples and comparative examples with a cured film thickness of 20 μm were 6 or higher, which are sufficient OD values ​​for use as a black opacifier. The thickness of the film after curing: 10 μm or 20 μm is achieved by using the same method as [the fabrication of the test substrate], drawing in 5 μm increments using an inkjet printer, and then UV curing it until the predetermined film thickness is formed.

[0063]

[0064] As can be seen from the evaluation results of the above-mentioned OD values ​​and the results shown in Table 2, the embodiments using the curable resin composition of the present invention can form a cured film that, in addition to high opacity, has good surface curing properties, exhibits stable adhesion under high temperature and high humidity conditions, and also has high hardness after curing. Furthermore, the evaluation results of Examples 1, 3, 5, and 6, in which (a) the mass ratio of an alicyclic epoxy compound having ester bonds in the molecule to (b) an alicyclic epoxy compound without ester bonds in the molecule is set to a more preferred range of 8:100 to 25:100, and the mass ratio of (B) the oxybutane compound to the aforementioned (A) epoxy compound is set to a more preferred range of 10:100 to 20:100, are the best results within the evaluation criteria. In particular, the results regarding cross-cutting (adhesion at 85°C and 85%RH) and pencil hardness under high temperature and high humidity conditions are better than those of the other embodiments.

[0065] In contrast, Comparative Examples 1 and 2, in which the mass ratio of (a) alicyclic epoxy compounds with intramolecular ester bonds to (b) alicyclic epoxy compounds without intramolecular ester bonds was outside the range of 43:100 to 50:100, and Comparative Example 3, which did not contain alicyclic epoxy compounds with intramolecular ester bonds (a), showed slightly worse cross-cutting (initial adhesion) compared to the Examples. Regarding cross-cutting under high temperature and high humidity conditions (85°C, 85%RH adhesion), the peeling of the hardened coating was the worst result within the evaluation criteria. Furthermore, the pencil hardness of Comparative Examples 1 to 3 was also the worst result within the evaluation criteria. Although the evaluation result of cross-cutting of Comparative Example 4 was good, its pencil hardness and finger feel were the worst results within the evaluation criteria.

Claims

1. A curable resin composition comprising (A) an epoxy compound, (B) an oxybutane compound, (C) a photoacid generator, and (D) a black colorant, wherein the aforementioned (A) epoxy compound comprises (a) an alicyclic epoxy compound having intramolecular ester bonds and (b) an alicyclic epoxy compound not having intramolecular ester bonds in a mass ratio ranging from 5:100 to 30:100, and the aforementioned (B) oxybutane compound and the aforementioned (A) epoxy compound are in a mass ratio ranging from 10:100 to 20:

100.

2. The curable resin composition as claimed in claim 1, wherein, It has a viscosity of 5~20 mPa·s at 50℃.

3. The curable resin composition as claimed in claim 1, wherein, The aforementioned (b) alicyclic epoxy compounds that do not have ester bonds in their molecules have 2 functional epoxy groups.

4. The curable resin composition as claimed in claim 1 or 2, wherein, The aforementioned (D) black colorant is carbon black, and contains 5 or more parts by mass relative to the total of 100 parts by mass of the aforementioned (A) epoxy compound and (B) cyclobutane compound.

5. The curable resin composition as claimed in claim 1 or 2, wherein the aforementioned epoxy compound (A) comprises, in a mass ratio ranging from 8:100 to 25:100, (a) an alicyclic epoxy compound having ester bonds in the molecule and (b) an alicyclic epoxy compound not having ester bonds in the molecule.