JPWO2013077307A1 - Hard coating composition - Google Patents

Abstract

To provide a hard coating composition having excellent extensibility and capable of forming a hard coating layer having high hardness and transparency.
A bisphenol A type epoxy resin (a) having a number average molecular weight of 900 to 7,000 and / or a secondary hydroxyl group and / or a secondary hydroxyl group, a melamine resin (b), a photopolymerization initiator (c) And a polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomeric compound (d) having at least one hydroxyl group.

Description

  The present invention relates to a hard coating composition that has excellent extensibility and can form a hard coating layer having high hardness and transparency.

  Hard coatings are used for a wide range of applications such as displays, IT and mobile devices such as mobile phones and laptop computers, other home appliances, miscellaneous goods, automobile interiors and exteriors, and are formed to protect the objects to be painted from being damaged. As the application of hard coating becomes wider in this way, good molding performance for moldings having a wide variety of shapes such as acute angles and curved surfaces is being required. For this reason, it is desired to maintain both the extensibility that can follow various moldings while maintaining the original high hardness of the hard coating.

  In addition to hard physical properties such as high hardness and extensibility, it is highly transparent and visual effects such as turbidity are not recognized in the hard coating from the viewpoint of not damaging the aesthetics of the molded product. It has been demanded. Furthermore, in the production of a hard coating, from the viewpoint of productivity, it is an important factor that the usable time (pot life / pot life) of the hard coating composition is long. Further, the prolonged pot life is also an important issue in terms of manufacturing.

  Japanese Unexamined Patent Publication No. 2009-62499 (Patent Document 1) includes a urethane acrylate obtained by reacting a urethane oligomer using a polyol having an alkyl group introduced in the side chain and a polyfunctional acrylate containing a hydroxyl group as a main component. An ultraviolet curable resin composition having a glass transition temperature measured by a scanning calorimeter (DSC) of 110 ° C. or higher is described (claim 1 and the like). This composition describes that a hard coating film having high hardness and high flexibility can be obtained. Since the composition described in Patent Document 1 is an ultraviolet curable resin composition, the hardness of the hard coating film can be further improved by using another curing method such as thermosetting together. There is room for.

  On the other hand, in the field of protective sheets and protective layers, a technique using a thermosetting method in combination with ultraviolet curing has also been proposed. For example, in JP-A-9-290491 (Patent Document 2), in a surface protective sheet in which at least a protective layer is provided on one side of a base sheet and at least an adhesive layer is provided on the opposite side, the protective layer is ) Thermal crosslinking reaction of an active energy ray-curable resin composition containing, as active ingredients, a polymer having an acrylic equivalent of 100 to 300 g / eq, a hydroxyl value of 20 to 500, and a weight average molecular weight of 5,000 to 50,000 and a polyfunctional isocyanate. A surface protective sheet comprising a product is described (claim 1 and the like). However, since such a resin composition has high reactivity between the hydroxyl group in the polymer and the isocyanate group of the polyfunctional isocyanate, there is a problem that the reaction proceeds even at room temperature. Therefore, there exists a subject that the useable time (pot life) of a composition becomes short and the coating workability | operativity of a protective layer is inferior.

  JP 2005-206778 A (Patent Document 3) discloses a compound (A) having a total of two or more active methylene groups and / or active methine groups in one molecule, a compound (B) having a (meth) acryloyl group (B ) And a photopolymerization initiator (C) are described (claim 1 and the like). And as a formation method of the protective layer by this composition, after making B-stage by heating, the method of irradiating with an energy ray and hardening is described (Claim 10 and 12 etc.). However, in the composition described in Patent Document 3, the (meth) acryloyl group of compound (B) reacts with the active methylene group and / or active methine group of compound (A) in the previous heating step. Resulting in. Therefore, since the remaining number of (meth) acryloyl groups that are cured in the subsequent energy beam irradiation step is reduced, it is difficult to form a high-hardness protective layer even when energy beam irradiation is performed. There are challenges.

JP 2009-62499 A Japanese Patent Laid-Open No. 9-290491 JP 2005-206778 A

  An object of the present invention is to provide a hard coating composition that has excellent extensibility and can form a hard coating layer having high hardness and transparency.

The present invention
A bisphenol A type epoxy resin (a) having a number average molecular weight of 900 to 7,000 and having a secondary hydroxyl group and / or a secondary hydroxyl group,
Melamine resin (b),
Photopolymerization initiator (c),
A polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomeric compound (d) having at least one hydroxyl group,
A hard coating composition is provided, which solves the above problems.

  It is preferable that solid content of the said bisphenol A type and / or bisphenol F type epoxy resin (a) is 1-60 mass parts among 100 mass parts of resin solid content of a hard-coating composition.

  The solid content of the melamine resin (b) is 20 to 1,500 parts by mass with respect to 100 parts by mass of the solid content of the bisphenol A type and / or bisphenol F type epoxy resin (a). preferable.

  The melamine resin (b) is preferably a melamine resin having a melamine mononuclear content of 30% by mass or more.

The hard coating composition of the present invention further includes a polyfunctional (meth) acrylate monomer having no hydroxyl group and / or an oligomer compound (e) having no hydroxyl group,
And it is preferable that solid content of the total amount of this component (d) and a component (e) is 30-75 mass parts among 100 mass parts of resin solid content of a hard coating composition.

The hard coating composition is:
(1) After applying the hard coating composition, a heat curing step of heating to 50 to 200 ° C., and then an active energy ray curing step of irradiating an active energy ray of 50 to 1,000 mJ / cm ² , or ,
(2) After applying the hard coating composition, an active energy ray curing step of irradiating an active energy ray of 50 to 1,000 mJ / cm ² , then heating to 50 to 200 ° C., a thermosetting step,
It is preferable to be cured by any of the above.

  It is preferable that the hard coating layer obtained by the hard coating composition has a haze value of less than 1%.

  The object to be coated with the hard coating composition is preferably a thermoplastic film.

  The present invention also provides a hard coating layer obtained by the above hard coating composition and having a haze value of less than 1%.

The hard coating composition of the present invention includes a component (a) having a hydroxyl group and a component component (d) having a hydroxyl group, which react with the melamine resin (b) under heating conditions. By reacting these components (a), (d), and melamine resin (b) under heating conditions, a three-dimensional network structure is formed. Thereby, in the hard coating layer obtained, there exists an advantage that favorable extensibility and high hardness are exhibited. And the hydroxyl group in the component (a) contained in the hard-coating composition of this invention contains the secondary hydroxyl group, and the number average molecular weight of the component (a) is limited to the range of 900-7,000. . Thereby, there is an advantage that transparency and extensibility in the obtained hard coating layer are improved, and storage stability of the hard coating composition and longer pot life are improved.
Further, the hard coating composition of the present invention contains a photopolymerization initiator (c) and a component (d) having a hydroxyl group and a (meth) acryloyl group. By including these components (c) and (d), a hard coating layer having high hardness can be obtained by irradiation with active energy rays. Furthermore, when the component (d) has a hydroxyl group, there is an advantage that a suitable crosslinking density can be obtained and a hard coating layer having high extensibility can be obtained.
As described above, in the hard coating composition of the present invention, the four specific components of the above components (a) to (d) are contained, so that the high hardness required in the hard coating layer is maintained and stretched. It is characterized by a variety of performances being achieved and good transparency.

Hard coating composition The hard coating composition of the present invention is used to protect an object to be coated from being damaged,
A bisphenol A type epoxy resin (a) having a number average molecular weight of 900 to 7,000 and having a secondary hydroxyl group and / or a secondary hydroxyl group,
Melamine resin (b),
Photopolymerization initiator (c),
A polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomeric compound (d) having at least one hydroxyl group,
including.
Hereinafter, each component will be described.

Bisphenol A type and / or bisphenol F type epoxy resin (a)
The epoxy resin of component (a) contained as a binder component in the hard coating composition of the present invention has a number average molecular weight of 900 to 7,000 and has a bisphenol A type and / or a secondary hydroxyl group having a secondary hydroxyl group. It is the bisphenol F type epoxy resin (a) which has. This epoxy resin (a) can be synthesized by reacting bisphenol A and / or bisphenol F with epichlorohydrin.

  The epoxy resin (a) has a number average molecular weight of 900 to 7,000. When the number average molecular weight of the epoxy resin (a) is in the above range, there is an advantage that high hardness and extensibility of the hard coating layer obtained by the hard coating composition are ensured. When the number average molecular weight of the epoxy resin (a) is less than 900, the hardness of the obtained hard coating layer becomes low and the extensibility is inferior. On the other hand, when the number average molecular weight of the epoxy resin (a) exceeds 7,000, the transparency of the obtained hard coating layer decreases, that is, the haze value increases.

  In this specification, a number average molecular weight means the value measured by polystyrene conversion using gel permeation chromatography (GPC, Shimadzu Corp. make).

  Further, since the hydroxyl group of the epoxy resin (a) is a secondary hydroxyl group, the reaction with the melamine resin (b) at room temperature is suppressed, and the epoxy resin (a) and the melamine are heated under heating conditions. Resin (b) will react. Thereby, there exists an advantage that the usable time (pot life) of a hard-coating composition becomes long.

  A commercially available product may be used as the epoxy resin (a) in the present invention. As commercially available products, for example, “epototo YD-011”, “epototo YD-014”, “epototo YD-019” manufactured by Nippon Steel Chemical Co., Ltd .; “jER1003”, “jER1004” manufactured by Mitsubishi Chemical Co., Ltd. ”,“ JER1009 ”,“ jER1010 ”;“ Epicron 1050 ”,“ Epicron 3050 ”,“ Epicron HM-091 ”manufactured by DIC, and the like. Examples of the bisphenol F type epoxy resin include “jER4007P” manufactured by Mitsubishi Chemical Corporation.

  As the epoxy resin (a) in the present invention, a copolymer epoxy resin of bisphenol A and bisphenol F can also be used. Examples of such a copolymerized epoxy resin include “Epiclon 7070-50M” manufactured by DIC.

  As the epoxy resin (a) in the present invention, a modified epoxy resin obtained by modifying a part of the epoxy group and / or secondary hydroxyl group contained in the epoxy resin with, for example, an amine, caprolactone, urethane, acid anhydride or the like may be used. it can. Examples of such a modified epoxy resin include “Epiclon P439” (modified epoxy resin in which an epoxy group is amine-modified) manufactured by DIC.

  The said epoxy resin (a) may be used individually by 1 type, and may use 2 or more types together.

  The content of the epoxy resin (a) is preferably 1 to 60 parts by mass, more preferably 1 to 35 parts by mass, out of 100 parts by mass of the resin solid content of the hard coating composition, and 3 to 25 More preferably, it is part by mass. When the epoxy resin (a) is contained in the above range, there is an advantage that good extensibility and high hardness in the obtained hard coating layer can be ensured.

  By including the epoxy resin (a), the hard coating composition of the present invention has an advantage that good adhesion of the obtained hard coating layer to an object to be coated can be obtained. Moreover, when the said epoxy resin (a) has an aromatic ring structure, there exists an advantage that favorable mechanical strength in a hard coating layer obtained, abrasion resistance, and abrasion resistance are acquired.

Melamine resin (b)
Melamine resin (b) is a curing agent in the hard coating composition of the present invention. The melamine resin (b) reacts at room temperature with the epoxy resin (a) and the hydroxyl group of the polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or the oligomer compound (d) having at least one hydroxyl group. In addition, since the self-condensation reaction of the melamine resin itself does not easily occur at room temperature, there is an advantage that the progress of the reaction during storage can be suppressed well and the storage stability is improved. Examples of the melamine resin (b) include methylolated melamines such as dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, hexamethylolmelamine; alkyletherified melamine of methylolated melamine and alcohol; Can do.

  For example, by heating melamine and formaldehyde under basic conditions, methylolated melamines such as dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, and hexamethylol melamine can be obtained. By reacting the methylolated melamine thus obtained with a lower alcohol under acidic conditions, part or all of the methylol group can be etherified to obtain an alkyl etherified melamine.

  Examples of the lower alcohol used for the reaction with methylolated melamine include methanol, ethanol, n-propanol, isopropanol, n-butanol, and isobutanol. These lower alcohols may be used alone or in combination of two or more.

  The alkyl etherified melamine resin may be one in which all methylol groups of methylolated melamine are etherified (completely etherified). Alternatively, a methylol group partially etherified and a methylol group and / or imino group remaining (partial etherification) may be used.

  In the present invention, it is more preferable to use a methyl etherified melamine resin, a butyl etherified melamine resin, or a methyl-butyl mixed etherified melamine resin that is completely etherified or partially etherified as the melamine resin (b).

From the viewpoint of maintaining compatibility with the components (a) and (d), the melamine resin (b) preferably has a melamine mononuclear body content of 30% by mass or more, and 40% by mass or more. More preferably. The melamine mononuclear body content rate in this specification means the ratio of mononuclear melamine resin having a polymerization degree of 1 contained in the entire melamine resin. This melamine mononuclear body content rate is a value (%) obtained by the peak area ratio of the mononuclear body portion to the total peak area of the melamine resin as measured by gel permeation chromatography (GPC).

  A commercially available product may be used as the melamine resin (b). As commercial products, for example, “Cymel 300” (melamine mononuclear content 82%), “Cymel 350” (melamine mononuclear content 72%), “Cymel 370N” (melamine mononuclear) manufactured by Nippon Cytec Industries, Ltd. Body content 38%), "Cymel 325" (melamine mononuclear content 48%), "My Coat 715" (melamine mononuclear content 61%), "Cymel 701" (melamine mononuclear content 53) %), “Cymel 238” (melamine mononuclear content 64%), “My Coat 212” (melamine mononuclear content 62%), “My Coat 506” (melamine mononuclear content 55%), etc. Can be mentioned.

  A melamine resin (b) may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  The solid content of the melamine resin (b) is 20 with respect to 100 parts by mass of the solid content of the bisphenol A type and / or F type epoxy resin (a) from the viewpoint of extensibility and hardness of the hard coating layer obtained. It is preferably ˜1,500 parts by mass, and more preferably 70 to 1,000 parts by mass. In the hard coating composition of the present invention, when the content of the melamine resin (b) is in the above range, excellent extensibility is achieved while maintaining high hardness.

  Moreover, it is preferable that content of the melamine resin (b) in a hard coating composition is 5-45 mass parts among 100 mass parts of resin solid content of a hard coating composition, and is 15-40 mass parts. Is more preferable. When the content of the melamine resin (b) is less than 5 parts by mass, the amount of the formed three-dimensional network structure is insufficient, and there is a possibility that high hardness cannot be obtained in the obtained hard coating layer. On the other hand, when the content of the melamine resin (b) exceeds 45 parts by mass, sufficient extensibility may not be obtained.

  The melamine resin (b) undergoes a curing reaction with the component (a) and the component (d) when the composition is heated. The melamine resin (b) also undergoes a curing reaction due to self-condensation upon heating. As a result, a three-dimensional network structure is formed in the hard coating layer. In the hard coating layer, a three-dimensional network structure derived from the curing reaction of the melamine resin (b) is formed, whereby the hard coating layer has improved extensibility and has a high hardness. There is an advantage.

Photopolymerization initiator (c)
The hard coating composition of the present invention contains a photopolymerization initiator (c). By including the photopolymerization initiator (c), the curability of the hard coating composition with respect to irradiation with active energy rays such as ultraviolet rays is improved.

  Specific examples of the photopolymerization initiator (c) include alkylphenone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, titanocene photopolymerization initiators, and oxime ester polymerization initiators. It is done.

  Examples of the alkylphenone photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl- Propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- {4- [4- ( 2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl ] -1- [4- (4-morpholinyl) phenyl] -1-butanone and the like.

  Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and the like.

  Examples of titanocene-based photopolymerization initiators include bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) -phenyl) titanium. Is mentioned.

  Examples of the oxime ester polymerization initiator include 1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], ethanone, 1- [9-ethyl-6- (2 -Methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime), oxyphenylacetic acid, 2- [2-oxo-2-phenylacetoxyethoxy] ethyl ester, 2- (2-hydroxy And ethoxy) ethyl ester.

  Further, hydrogen abstraction initiators such as benzophenone, 2,4,6-trimethylbenzophenone, methyl benzoylbenzoate, 2,4-diethylthioxanthone, 2-ethylanthraquinone, camphorquinone, and the like can be used.

  A photoinitiator (c) may be used individually by 1 type, and 2 or more types may be mixed and used for it. The solid content of the photopolymerization initiator is preferably 1 to 10 parts by mass, and more preferably 3 to 8 parts by mass with respect to 100 parts by mass of the resin solid content of the hard coating composition.

Polyfunctional (meth) acrylate monomer and / or oligomer compound (d) having at least one hydroxyl group
The polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or the oligomeric compound (d) having at least one hydroxyl group contained in the hard coating composition of the present invention has an activity after the hard coating composition is applied. By irradiation with energy rays, a curing reaction based on the reaction of the (meth) acryloyl group occurs, and a hard coating layer having high hardness is obtained. Furthermore, this component (d) has a hydroxyl group in addition to the (meth) acryloyl group. And this hydroxyl group will react with a melamine resin (b) in the heating process after apply | coating a hard-coating composition. Thereby, there exists an advantage that the crosslinking degree of the hard coating layer obtained improves and a tougher hard coating layer is obtained.

  The polyfunctional (meth) acrylate monomer and / or oligomer compound (d) preferably has three or more (meth) acryloyl groups. By having three or more (meth) acryloyl groups, there is an advantage that a hard coating layer having high hardness can be obtained after irradiation with active energy rays.

  Specific examples of the polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or the oligomer compound (d) having at least one hydroxyl group include, for example, hydroxypropylated trimethylolpropane triacrylate, 2-hydroxy-3 -Phenoxypropyl acrylate, isocyanuric acid ethylene oxide modified diacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and oligomers thereof. These monomers or oligomers may be used alone or in combination of two or more.

Polyfunctional (meth) acrylate monomer and / or oligomer compound (e) having no hydroxyl group
The hard coating composition of the present invention may further contain a polyfunctional (meth) acrylate monomer having no hydroxyl group and / or an oligomer compound (e) having no hydroxyl group, if necessary.

  In the case of industrially producing the above polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or oligomer compound (d) having at least one hydroxyl group, the polyfunctional (meth) acrylate having no hydroxyl group In many cases, a monomer and an oligomer compound (e) having no hydroxyl group are produced together and used without being separated. In the present invention, an industrially produced polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or oligomer compound (d) having at least one hydroxyl group and a polyfunctional (meth) acrylate having no hydroxyl group A mixture with a monomer and / or an oligomer compound (e) having no hydroxyl group may be used.

  Specific examples of the polyfunctional (meth) acrylate monomer having no hydroxyl group and / or the oligomer compound (e) having no hydroxyl group include, for example, trimethylolpropane triacrylate, tris (acryloxyethyl) isocyanurate, and ditrimethylolpropane. Examples include tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and oligomers thereof. These monomers or oligomers may be used alone or in combination of two or more.

  Of the resin solid content of 100 parts by mass of the hard coating composition, the total solid content of component (d) and component (e) is preferably 30 to 75 parts by mass, and 40 to 75 parts by mass. More preferably it is. When the solid content of the total amount of the component (d) and the component (e) is in the above range, an advantage that a good active energy ray curing performance is exhibited, whereby a hard coating layer having high hardness can be obtained. There is.

  Also, a polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomer compound (d) having at least one hydroxyl group, and a polyfunctional (meth) acrylate monomer having no hydroxyl group and / or an oligomer having no hydroxyl group The content ratio of the compound (e) is preferably (d) :( e) = 20: 80 to 95: 5 by mass ratio, and (d) :( e) = 30: 70 to 95: 5. More preferably.

Other Components In addition to the above components (a) to (d) and the necessary component (e), the hard coating composition of the present invention does not inhibit the effects of the present invention with other components such as additives. It may be included within the range. Examples of additives include hardeners such as antioxidants, ultraviolet absorbers, light stabilizers, photopolymerization initiation assistants, antistatic agents, polymerization inhibitors, surface conditioners, lubricants, antifoaming agents, leveling agents, and pigments. The additive etc. which are generally used in the field of a coating composition can be mentioned.

  The hard coating composition of the present invention may contain a solvent as required. The solvent is not particularly limited. For example, hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ethyl acetate, butyl acetate, ethylene glycol monoethyl ether Ester solvents such as acetate; alcohol solvents such as methanol, ethanol and isopropanol; ether alcohol solvents such as ethylene glycol monoethyl ether and diethylene glycol monobutyl ether; amides such as dimethylformamide, diethylformamide, dimethylsulfoxide and N-methylpyrrolidone Solvents such as cellosolve solvents such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve. These solvents may be used alone or in combination of two or more.

  The hard coating composition of this invention may contain the thermosetting catalyst which functions as a catalyst with respect to the thermosetting reaction of a melamine resin (b) as needed. The thermosetting catalyst is not particularly limited, and examples thereof include phosphoric acid, a sulfonic acid compound, or an amine neutralized product of a sulfonic acid compound. Representative examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, and the like. The amine in the amine neutralized product of the sulfonic acid compound may be any of primary amine, secondary amine, and tertiary amine. These catalysts may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The hard coating composition of the present invention may contain an inorganic and / or organic filler as necessary, provided that the transparency of the resulting hard coating layer is not impaired. Examples of the inorganic filler include glass, mica, silica, colloidal silica, calcium silicate, talc, calcium carbonate, clay, barium sulfate, alumina, bentonite and the like. Examples of the organic filler include polymethyl methacrylate particles, polystyrene particles, poly (styrene / methyl methacrylate) copolymer particles, polyester particles, polycarbonate particles, polyimide particles, polyurethane particles, nylon particles, polyethylene particles, polypropylene particles, Examples thereof include silicone particles, polytetrafluoroethylene particles, polyvinylidene fluoride particles, polyvinylidene chloride particles, benzoguanamine / formalin condensate, and melamine / formalin condensate. These fillers may be used individually by 1 type, and 2 or more types may be mixed and used for them.

Preparation of hard coating composition The hard coating composition of the present invention includes, for example, the above epoxy resin (a), melamine resin (b), photopolymerization initiator (c), polyfunctional (meth) acrylate having at least one hydroxyl group. Mixing the monomer and / or oligomer compound (d) and, if necessary, the polyfunctional (meth) acrylate monomer and / or oligomer compound (e) having no hydroxyl group and other additives, solvents, catalysts, fillers, etc. Can be prepared. Examples of the mixer used in the preparation of the hard coating composition of the present invention include a mixer such as a roller mill, a ball mill, a bead mill, a sand grind mill, a pot mill, a paint shaker, and a disper.

2. Coating method and curing method of hard coating composition As a method of coating the hard coating composition of the present invention on an object to be coated, a commonly used coating method can be used without any particular limitation. As a coating method, for example, a known printing method such as gravure printing method, screen printing method, offset printing method, or blade coating method, rod coating method, roll coating method, roll doctor coating method, knife coating method, die coating method, Known coating methods such as a comma coating method, a reverse roll coating method, a transfer roll coating method, a kiss roll coating method, a curtain coating method, and a dip coating method may be used.

  By coating the hard coating composition, the thickness of the hard coating layer formed on the object to be coated can be variously selected according to the type and application of the object to be coated. As a film thickness, it can select suitably in the range of 1-100 micrometers, for example.

Examples of the object to be coated with the hard coating composition of the present invention include objects of various materials and forms such as various films and molded products. Specific examples of the base material constituting the object to be coated include Novaclear ^{(registered trademark)} SG007 (manufactured by Mitsubishi Chemical Corporation ^), Deacrail ^{(registered trademark)} series (manufactured by Mitsubishi Plastics), and Soft Shine ^{(registered trademark).} Series, Cosmo Shine ^{(registered trademark)} series (made by Toyobo Co., Ltd.), etc.
Opyuran ^{(registered trademark)} TPX series (manufactured by Mitsui Chemicals, Inc.), Torre fan (manufactured by Toray Industries, synthetic Film Co., Ltd.) ^{(registered trademark)} series, polyolefin-based films such as Te flex ^(R) series (manufactured by Teijin DuPont Films);
Acrylic film such as acrylprene ^{(registered trademark)} series (Mitsubishi Rayon);
And the like.
Examples of the substrate further include a single film, a co-extruded film, a laminate film, and a release treatment film subjected to a release treatment. Here, the release treatment applied to the release treatment film is not particularly limited, and examples thereof include silicone treatment, non-silicone treatment, urethane resin coating treatment, and melamine resin coating treatment. Moreover, the molded object comprised by these base materials can also be used as a to-be-coated object.

  The hard coating composition of the present invention can be suitably used in coating with a thermoplastic film as an object to be coated. The hard coating composition of this invention is hardened | cured by two types of hardening processes, a thermosetting process and an active energy ray hardening process. Therefore, in the thermosetting step, there is an advantage that the reaction proceeds and a hard coating film having high hardness can be obtained even when heating is performed in a temperature range that does not adversely affect the thermoplastic film.

The hard coating composition of the present invention is applied to an article to be coated, and then the following (1) or (2):
(1) After applying the hard coating composition, a heat curing step of heating to 50 to 200 ° C., and then an active energy ray curing step of irradiating an active energy ray of 50 to 1,000 mJ / cm ² , or ,
(2) After applying the hard coating composition, an active energy ray curing step of irradiating an active energy ray of 50 to 1,000 mJ / cm ² , followed by heating to 50 to 200 ° C., a thermosetting step:
It can be cured by any of these steps.

  The said thermosetting process can be heated, for example using a hot air drying furnace or a heating furnace. The heating time can be appropriately selected depending on the heating temperature, but is generally in the range of 30 seconds to 10 minutes. By such a thermosetting step, the components (a), (b), and (d) undergo a thermosetting reaction to form a crosslink. In addition, the solvent in the hard coating composition, which is included as necessary, is removed.

  The active energy ray curing step can be performed by irradiating active energy rays such as ultraviolet rays, electron beams, X-rays, and gamma rays. The active energy ray can be irradiated using, for example, a fusion lamp, a high-pressure mercury lamp, a metal halide lamp, or the like. By such an active energy ray curing step, the component (d) and the component (e) as required are cured, and a hard coating layer having high hardness is formed.

The hard coating layer formed using the hard coating composition of the present invention is characterized by being highly transparent and having good extensibility and high hardness. As described above, in the hard coating composition of the present invention, the specific components of the above components (a) to (d) are contained, so that the high hardness required in the hard coating layer is maintained and the extensibility is also achieved. Will be.
Regarding the extensibility of the hard coating layer thus obtained, the numerical value of R according to the cylindrical mandrel method is preferably 4R or less, more preferably 3R or less, in accordance with JIS K 5600-5-1. The hardness of the hard coating layer is preferably a pencil hardness of 2.0H or higher, and more preferably 2.5H or higher. The pencil hardness is measured by a pencil hardness test according to JIS K 5600-5-4, and a formula of “pencil hardness” = “minimum hardness at which scratches occur” − “(number of scratches in 10) / 10”. Can be obtained.
Further, the hard coating layer has a feature that extremely high transparency is also achieved. The transparency can be measured by a haze value. The haze value is preferably 1.0% or less, and more preferably 0.5% or less. The measuring method of a haze value can measure the film obtained from the hard-coating composition with the commercially available haze meter according to the prescription | regulation of JISK7136, for example.

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Example 1
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 15 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 30 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 mass parts, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) 50 parts by mass of the solid content was mixed with methyl ethyl ketone to adjust the nonvolatile content to 40% by mass to obtain a hard coating composition.

The obtained hard coating composition was coated on a PET film (thickness: 100 μm) with a bar coater and heated at 150 ° C. for 1 minute to remove the solvent, thereby forming a thermosetting hard coating layer having a thickness of 5 μm. Obtained.
Then, the hard coating film was obtained by irradiating this hard coating layer with a high-pressure mercury lamp (120 W / cm ² ) so as to have an ultraviolet ray energy of 300 mJ / cm ² .

Example 2
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to jER1004 (bisphenol A type epoxy resin, number average molecular weight 1400, manufactured by Mitsubishi Chemical Corporation).

Example 3
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to jER1010 (bisphenol A type epoxy resin, number average molecular weight 5500, manufactured by Mitsubishi Chemical Corporation).

Example 4
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to jER4007P (bisphenol F type epoxy resin, number average molecular weight 4500, manufactured by Mitsubishi Chemical Corporation).

Example 5
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3800, manufactured by Mitsubishi Chemical Corporation) solid content 35 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 15 masses Parts, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) solid content 5 parts by mass, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) 45 parts by mass was mixed with methyl ethyl ketone to adjust the non-volatile content to 40% by mass to obtain a hard coating composition.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 6
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 25 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 25 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 mass parts, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) A hard coating composition was obtained by mixing 45 parts by mass of solids with methyl ethyl ketone and adjusting the non-volatiles to 40% by mass.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 7
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 5 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 35 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 mass parts, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) A hard coating composition was obtained by mixing 55 parts by mass of solid content with methyl ethyl ketone and adjusting the nonvolatile content to 40% by mass.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 8
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 3 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 36 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 parts by mass, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) A hard coating composition was obtained by mixing 56 parts by mass of solid content with methyl ethyl ketone and adjusting the nonvolatile content to 40% by mass.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 9
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 1.5 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) 30 parts by mass of solids, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 parts by mass of solids, and Aronix M400 (a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, Toa Gosei Co., Ltd.) Manufactured) A solid content of 63.5 parts by mass was mixed with methyl ethyl ketone to adjust the nonvolatile content to 40% by mass to obtain a hard coating composition.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 10
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that Cymel 325 was changed to My Coat 525 (melamine resin, melamine mononuclear content 25% by mass, manufactured by Nippon Cytec Industries, Inc.). It was.

Example 11
jER1004 (bisphenol A type epoxy resin, number average molecular weight 1,400, manufactured by Mitsubishi Chemical Corporation) solid content 50 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 12 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 mass parts, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) A solid content of 33 parts by mass was mixed with methyl ethyl ketone to adjust the non-volatile content to 40% by mass to obtain a hard coating composition.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Example 12
jER1009 (bisphenol A type epoxy resin, number average molecular weight 3,800, manufactured by Mitsubishi Chemical Corporation) solid content 20 parts by mass, Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries, Inc.) solid content 5 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) solid content 5 parts by mass, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) 70 mass parts of solid content was mixed with methyl ethyl ketone, and it adjusted so that a non volatile matter might be 40 mass%, and the hard-coating composition was obtained.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Comparative Example 1
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to jER828 (bisphenol A type epoxy resin, number average molecular weight 370, manufactured by Mitsubishi Chemical Corporation).

Comparative Example 2
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to Epicron EXA192 (bisphenol A type epoxy resin, number average molecular weight 9,000, manufactured by DIC Corporation).

Comparative Example 3
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that jER1009 was changed to Epicron H332 (polyether ester type epoxy resin, number average molecular weight 3,000, manufactured by DIC Corporation).

Comparative Example 4
Cymel 325 (melamine resin, melamine mononuclear content 48% by mass, manufactured by Nippon Cytec Industries Co., Ltd.) solid content 45 parts by mass, Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) solid content 5 parts by mass , And Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) 50 parts by mass of solid content was mixed with methyl ethyl ketone to adjust the nonvolatile content to 40% by mass, and hard coating A composition was obtained.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Comparative Example 5
Irgacure 184 (1-hydroxy-cyclohexyl-phenyl-ketone, manufactured by BASF) 5 mass parts, and Aronix M400 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toa Gosei Co., Ltd.) 95 mass Parts were mixed with methyl ethyl ketone to adjust the non-volatile content to 40% by mass to obtain a hard coating composition.
A hard coating film was obtained in the same manner as in Example 1 using the obtained hard coating composition.

Comparative Example 6
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that Cymel 325 was changed to Coronate HX (trimer of 1,6-hexane diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.).

Comparative Example 7
A hard coating composition and a hard coating film were obtained in the same manner as in Example 1 except that Aronix M400 was changed to NK ester A-TMMT (pentaerythritol tetraacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.).

  The following evaluation was performed using the hard coating compositions and hard coating films obtained in the above Examples and Comparative Examples.

After allowing the pot life hard coating composition to stand at room temperature, the gelation state (the state in which the hard coating composition solidifies from a liquid state to a non-flowable jelly state) was visually observed to evaluate the time for gelation to occur. In this evaluation, the longer the time until the occurrence of gelation, the better the storage stability of the composition.
From the viewpoint of production, it is preferable that gelation does not occur for 12 hours or more, and more preferable that gelation does not occur for 24 hours or more.

Pencil hardness The pencil hardness test of the hard coating film was performed according to the specification of JIS K 5600-5-4 and evaluated by the following method.
“Pencil hardness” = “Minimum hardness to scratch” − “(Number of scratches in 10) / 10”

For example, if 5 of 10 scratches are made with a 3H pencil, 3- (5/10) = 2.5H. The larger the H value of the pencil hardness, the higher the hardness of the hard coating layer.
The pencil hardness is preferably 2.0H or more. 2.5H or more is more preferable.

Bending test The hard coating film was evaluated by the cylindrical mandrel method in accordance with JIS K 5600-5-1. It shows that the extensibility of a hard coating layer is so favorable that the numerical value of R is small.
In this bending test evaluation, it is preferably 4R or less, more preferably 3R or less.

The hard coating film was measured by a haze meter (NDH-2000 manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the rules of haze JIS K 7136. It shows that transparency of a hard-coating layer is so high that a haze value is small (it is favorable).

All of the hard coating compositions of Examples 1 to 12 did not gel after 24 hours, and it was confirmed that the pot life was long. And it was confirmed that all the hard coating films obtained using the hard coating compositions of Examples 1 to 12 have high hardness and extensibility and high transparency.
Comparative Example 1 is a comparative example in which the number average molecular weight of the epoxy resin (a) is less than 900. The hard coating film obtained using the composition of Comparative Example 1 had a hardness as low as less than 2H and also had poor extensibility.
Comparative Example 2 is a comparative example in which the number average molecular weight of the epoxy resin (a) exceeds 7,000. The hard coating film obtained using the composition of Comparative Example 2 had a very high haze value of 7% and was inferior in transparency.
Comparative Example 3 is a comparative example using a polyether ester type epoxy resin having no bisphenol A type / bisphenol F type structure as an epoxy resin. The hard coating film obtained by using the composition of Comparative Example 3 had a hardness as low as less than 2H and a haze value as high as 4%, which was inferior in transparency.
Comparative Example 4 is a comparative example that does not include the epoxy resin (a). The hard coating film obtained using the composition of Comparative Example 4 was inferior in extensibility.
Comparative Example 5 is a comparative example in which the epoxy resin (a) and the melamine resin (b) are not included. The hard coating film obtained using the composition of Comparative Example 5 was greatly inferior in extensibility.
Comparative Example 6 is a comparative example using a polyisocyanate compound instead of the melamine resin (b). The composition of Comparative Example 6 gelled after 2 hours, and the pot life was extremely short.
Comparative Example 7 is a comparative example that does not include a polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomer (d) having at least one hydroxyl group. The hard coating film obtained using the composition of Comparative Example 7 was inferior in extensibility.

  The hard coating layer formed using the hard coating composition of the present invention is characterized by being highly transparent and having good extensibility and high hardness. By using the hard coating composition of the present invention, there is an advantage that a hard coating layer having high extensibility and excellent molding performance and having high transparency and high hardness can be obtained.

Claims (9)

A bisphenol A type epoxy resin (a) having a number average molecular weight of 900 to 7,000 and having a secondary hydroxyl group and / or a secondary hydroxyl group,
Melamine resin (b),
Photopolymerization initiator (c),
A polyfunctional (meth) acrylate monomer having at least one hydroxyl group and / or an oligomeric compound (d) having at least one hydroxyl group,
A hard coating composition comprising:   The hard content according to claim 1, wherein the solid content of the bisphenol A type and / or bisphenol F type epoxy resin (a) is 1 to 60 parts by mass out of 100 parts by mass of the resin solid content of the hard coating composition. Coating composition.   The solid content of the melamine resin (b) is 20 to 1,500 parts by mass with respect to 100 parts by mass of the solid content of the bisphenol A type and / or bisphenol F type epoxy resin (a). Or the hard coating composition of 2.   The hard-coating composition as described in any one of Claims 1-3 whose said melamine resin (b) is a melamine resin whose melamine mononuclear body content rate is 30 mass% or more. Furthermore, a polyfunctional (meth) acrylate monomer having no hydroxyl group and / or an oligomer compound (e) having no hydroxyl group,
The total solid content of the component (d) and the component (e) is 30 to 75 parts by mass out of 100 parts by mass of the resin solid content of the hard coating composition.
The hard coating composition as described in any one of Claims 1-4. The hard coating composition is:
(1) After applying the hard coating composition, a heat curing step of heating to 50 to 200 ° C., followed by irradiation with an active energy ray of 50 to 1,000 mJ / cm ² , or ,
(2) After applying the hard coating composition, an active energy ray curing step of irradiating an active energy ray of 50 to 1,000 mJ / cm ² , and then heating to 50 to 200 ° C., a thermosetting step,
Cured by any of the
Hard coating composition as described in any one of Claims 1-5. The haze value of the hard coating layer obtained by the hard coating composition is less than 1%.
Hard coating composition as described in any one of Claims 1-6.   The hard coating composition according to any one of claims 1 to 7, wherein an object to be coated with the hard coating composition is a thermoplastic film.   A hard coating layer obtained by the hard coating composition according to claim 1, having a haze value of less than 1%.