JP2015203770A - Hard coat film, coating liquid for forming hard coat layer, and method of manufacturing the hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a hard coat film in which poor appearance is hardly caused in the manufacturing steps and which has a hard coat layer with sufficient hardness.SOLUTION: A hard coat film 10 comprises a base material film 1 and a hard coat layer 2 laminated on the top of at least one surface of the base material film 1. In the hard coat film 10, the hard coat layer 2 is formed of a coating liquid containing a compound having an energy polymerizable functional group, a filler, a polymerization initiator, and a polythiol compound. A proportion of a variation Δbof a value bof the chromatic coordinate bstipulated in JIS K5600-4-4:1999 (ISO 7724-1:1984) after applying a heat treatment of keeping the hard coat film 1 in a 200°C environment for one hour, with respect to a value bof the chromatic coordinate bof the hard coat film 1 before the heat treatment, to a total thickness of the hard coat layer is less than 0.02 μm.

Description

  The present invention relates to a hard coat film, a coating liquid for forming a hard coat layer provided in the hard coat film, and a method for producing the hard coat film.

  A transparent substrate used as a protective member on the display side of an image display device such as a display, a touch panel, or a mobile phone has been conventionally made of glass, but has excellent shape workability such as being able to easily form a shape having a curved surface, Since it is preferable also from a viewpoint of weight reduction, adoption of a plastic film as a transparent substrate has been studied.

  A transparent substrate made of a plastic film has the advantages as described above. However, since the surface is easily damaged as compared with a conventional glass substrate, there is a problem of increasing the surface hardness. As a means for solving such a problem, the plastic film is composed of a hard coat film having a base material and a hard coat layer laminated on one surface of the base material, or the hard coat film is stuck on the plastic film substrate. Is mentioned.

  Further, even in a conventional glass substrate, a plastic film may be stuck on the outermost surface in order to prevent scattering when it is damaged. Also in this case, a hard coat film is used as the plastic film from the viewpoint of preventing damage.

  Such a hard coat film is required to have excellent durability capable of withstanding a durability test in a high temperature and high humidity environment, like a glass substrate made of a conventional inorganic material.

  In this regard, Patent Document 1 discloses, as a hard coat coating liquid capable of forming a hard coat layer having high adhesion, a monomer or oligomer (A) mainly composed of acrylate, and a polythiol compound (B) having two or more thiol groups. ) At least, and the weight ratio of the polythiol compound (B) in the composition is 5% by weight to 50% by weight.

JP 2012-197383 A

  Since the ene-thiol ultraviolet curing agent contained in the hard coat coating solution disclosed in Patent Document 1 is not subject to inhibition of curing by oxygen, it can obtain a good cured state and has high adhesion to the film substrate. It is disclosed in Patent Document 1 that the property can be obtained.

  However, as a result of studies by the present inventors, a hard coat film including a hard coat layer formed from a hard coat coating solution disclosed in Patent Document 1 may be yellowed when heated. It was revealed. When a hard coat film is used as an alternative material for a glass substrate, a product in which the hard coat film is incorporated (electronic devices such as smartphones, tablet PCs, notebook PCs, etc.) are used as glass substrates. The hard coat film must also meet the heat resistance standards that were met. Depending on the product manufacturing process, a transparent conductive material such as ITO may be laminated on the hard coat film by a dry process. In this case, the hard coat film is heated during the process and exposed to high temperatures. Sometimes it is done. Since the hard coat film is disposed on the display surface side of an image display device such as a liquid crystal element or an organic EL element, it is strongly required to be colorless and transparent even when subjected to the heating as described above.

  An object of this invention is to provide a hard-coat film provided with the hard-coat layer which does not produce discoloration easily even if it heats. Another object of the present invention is to provide a coating liquid for forming the hard coat layer and a method for producing a hard coat film using the coating liquid.

The present invention provided to achieve the above object is as follows.
(1) A hard coat film comprising a base film and a hard coat layer laminated on at least one surface of the base film, wherein the hard coat layer has an energy polymerizable functional group. JIS, which is formed from a coating solution containing a filler, a polymerization initiator, and a polythiol compound, and is subjected to heat treatment for holding the hard coat film in an environment of 200 ° C. for 1 hour. K5600-4-4: 1999: changes to the color coordinate ^{b *} value ^b _{* 0} before the heat treatment of the hard coat film of the color coordinates as specified in (ISO 7724-1 1984) ^{b *} value ^b _{* 1} weight The hard coat film, wherein a ratio of Δb ^* to the total thickness of the hard coat layer is less than 0.02 μm ⁻¹ .

(2) The hard coat film according to (1), wherein the total thickness of the hard coat layers is 5 μm or more.

(3) The mass of the content of the polymerization initiator relative to the sum of the content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound in the coating liquid. A hard coat film given in the above (1) or (2) whose ratio is 5 mass% or less.

(4) The mass ratio of the content of the polythiol compound to the sum of the content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound in the coating liquid. Is a hard coat film according to any one of (1) to (3), which is 1% by mass or more and less than 30% by mass.

(5) In the coating liquid, the mass ratio of the filler content to the sum of the content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound is The hard coat film according to any one of (1) to (4), which is 5% by mass or more and less than 70% by mass.

(6) The hard coat film according to any one of (1) to (5), wherein the pencil hardness is H or more.

(7) The base material is coated with a coating solution for forming a hard coat layer provided in the hard coat film according to any one of (1) to (6) above, on at least one surface of the base film. A method for producing a hard coat film, comprising: forming a coating film on a film; and irradiating the coating film with energy to form a hard coat layer on the substrate film.

  According to the present invention, there is provided a hard coat film that hardly causes yellowing even when heated at 200 ° C. for 1 hour. In addition, the present invention provides a coating liquid for forming a hard coat layer that hardly causes yellowing, and a method for producing a hard coat film using the coating liquid.

It is a schematic sectional drawing of the hard coat film which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the hard coat film which concerns on other one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
1. Hard Coat Film As shown in FIG. 1, a hard coat film 10 according to an embodiment of the present invention includes a base film 1 and a hard coat layer 2 laminated on one main surface 1A of the base film 1. With. As shown in FIG. 2, a hard coat film 10 according to another embodiment of the present invention includes a base film 1 and a hard coat layer laminated on one main surface 1 </ b> A of the base film 1. 2a and a hard coat layer 2b laminated on the other main surface 1B of the base film 1.

(1) Base Film The base film 1 included in the hard coat film 10 according to the present embodiment is not particularly limited as long as the base film 1 is colorless and transparent and has a film shape. The base film 1 according to one embodiment is made of a transparent plastic film. Examples of the transparent plastic film include polyolefin resins such as polyethylene, polypropylene, poly-4-methylpentene-1, and polybutene-1, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, and polyvinyl chloride resins. Film made of cellulose resin such as polyphenylene sulfide resin, polyether sulfone resin, polyethylene sulfide resin, polyphenylene ether resin, styrene resin, acrylic resin, polyamide resin, polyimide resin, cellulose acetate Or these laminated | multilayer films are mentioned. Among these, a polyethylene terephthalate film is particularly preferable.

  There is no restriction | limiting in particular as thickness of the base film 1 with which the hard coat film 10 which concerns on this embodiment is provided, It selects suitably according to the intended purpose of the hard coat film 10, and is 10-500 micrometers normally. From the viewpoint of improving the handleability and realizing weight reduction, the thickness of the base film 1 is preferably 200 μm or less, and more preferably 100 μm or less. The lower limit of the thickness of the base film 1 is not limited. From the viewpoint of improving the handleability, the thickness of the base film 1 is preferably 10 μm or more, and more preferably 20 μm or more.

The base film 1 included in the hard coat film 10 according to this embodiment may include a weathering agent such as an antioxidant, an ultraviolet absorber, and a light stabilizer.
As shown in FIG. 1, a base film 1 included in a hard coat film 10 according to an embodiment of the present invention has a metallic film formed by a technique such as vapor deposition or sputtering as desired, opposite to one main surface 1A. You may have on the main surface of the side.

  The base film 1 included in the hard coat film 10 according to the present embodiment has elements (hard coat layers 2, 2 a, 2 b, metallic coating) laminated on at least one of the main surfaces thereof. For example, a surface treatment by an oxidation method or a concavo-convex method may be applied for the purpose of increasing the peel strength against the adhesive layer. Examples of the oxidation method include corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. Examples include solvent processing methods. These surface treatment methods are appropriately selected depending on the type of the base film 1, but in general, the corona discharge treatment method is preferably used from the viewpoints of effects and operability. Further, a primer layer made of a silane coupling agent or the like may be provided.

(2) Hard Coat Layer The hard coat layers 2, 2 a, 2 b included in the hard coat film 10 according to this embodiment are compounds having an energy polymerizable functional group (also referred to as “polymerizable compound” in this specification). And a coating liquid containing a filler, a polymerization initiator, and a polythiol compound. Since this coating liquid contains a polymerization initiator, the polymerization reaction of the energy polymerizable compound can be advanced by irradiation of the coating liquid of the coating liquid with ultraviolet rays or application of heat to the coating film.

  As shown in FIG. 1, the hard coat layer 2 may be laminated on one surface of the base film 1, and as shown in FIG. 2, the hard coat layers 2 a and 2 b are the base film 1. It may be formed on both surfaces. Since the shrinkage phenomenon often occurs when the hard coat layers 2, 2 a, 2 b are formed from the coating film of the coating liquid, as shown in FIG. 2, the hard film is hard on both surfaces of the base film 1. The coating layers 2a and 2b are preferably formed from the viewpoint of curling suppression.

Hereinafter, the composition of the coating solution will be described.
(2-1) Polymerizable compound As long as the polymerizable compound which the coating liquid which concerns on one Embodiment of this invention contains has an energy polymerizable functional group, a specific structure and composition are not limited.

  Examples of the energy polymerizable functional group possessed by the polymerizable compound include ethylenically unsaturated groups such as (meth) acryloyl group, vinyl group, allyl group and styryl group. Among these, the energy polymerizable functional group is preferably a (meth) acryloyl group because of its high reactivity. Hereinafter, the case where the energy polymerizable functional group is a (meth) acryloyl group will be described as a specific example. In the present specification, the “(meth) acryloyl group” means at least one of an acryloyl group and a methacryloyl group. The same applies to other similar words.

  The polymerizable compound may be composed of one type of compound or may be composed of a plurality of types of compounds. The polymerizable compound may contain a monomer or a polymer. When the polymerizable compound contains a polymer, the polymer may be an oligomer or a polymer.

  In the case where the polymerizable compound contains a monomer, examples of such a monomer include pentafunctional or higher polyfunctional acrylate monomers. Examples of pentafunctional or higher polyfunctional acrylate monomers include dipentaerythritol pentaacrylate, propionic acid modified dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, caprolactone modified dipentaerythritol hexaacrylate, dipentaerythritol pentamethacrylate, propionic acid. Examples thereof include modified dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, and caprolactone-modified dipentaerythritol hexamethacrylate. Of these, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate are preferred.

  Examples of the monomer that the polymerizable compound may contain include a tetrafunctional or lower energy ray polymerizable monomer. Specific examples include monofunctional acrylates such as cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and isobonyl (meth) acrylate; 1,4-butanediol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (Meth) acrylate, dicyclopentanyl di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate , Ethylene oxide modified di (meth) acrylate phosphate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid Modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexa (meth) acrylate, pentaerythritol Examples thereof include ethoxytetraacrylate, ditrimethylolpropane tetraacrylate, and pentaerythritol tetraacrylate.

  In the case where the polymerizable compound includes an oligomer, examples of the oligomer include a polyester acrylate oligomer, an epoxy acrylate oligomer, a urethane acrylate oligomer, and a polyol acrylate oligomer.

  As a specific example of the polymerizable compound, there may be mentioned a case where the above-mentioned pentafunctional or higher polyfunctional acrylate monomer is used. Another specific example of the polymerizable compound includes a mixture of a polyfunctional acrylate monomer having 5 or more functional groups and an energy beam polymerizable oligomer and / or an energy beam polymerizable monomer having 4 or less functional groups.

  The content of the polymerizable compound in the coating liquid according to this embodiment is not limited. The hard coat layers 2, 2a, 2b can be appropriately formed, and the viscosity of the coating liquid may be set to be appropriate. The mass ratio of the polymerizable compound in the entire component (also referred to as “active ingredient” in the present specification) other than the solvent in the coating liquid is preferably 20% by mass or more and 95% by mass or less, and 30% by mass or more. It is preferable that it is 90 mass% or less.

(2-2) Filler The coating liquid which concerns on one Embodiment of this invention contains a filler. The type, shape, and content of the filler are not limited as long as the hard coat layers 2, 2 a, 2 b have appropriate optical characteristics, that is, are colorless and transparent. When the coating liquid contains a filler, it is possible to increase the hardness of the hard coat layers 2, 2 a and 2 b formed from the coating liquid. The filler contained in the coating liquid which concerns on this embodiment may be comprised from 1 type, and may be comprised from 2 or more types.

  The filler may contain an inorganic material or an organic material, but from the viewpoint of easily increasing the hardness of the hard coat layers 2, 2 a, 2 b, the filler is an inorganic material. It is preferable that the material is contained, and it is more preferable that the material is composed of an inorganic material.

  Examples of materials that give inorganic fillers include metal oxides such as silica, aluminum oxide, zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide; And metal fluorides such as magnesium fluoride and sodium fluoride. Metals, metal sulfides, metal nitrides, and the like may be used as long as the hard coat layers 2, 2a, 2b are colorless and transparent.

  Among these, silica and aluminum oxide are preferable as materials for providing an inorganic filler because it is easier to increase the hardness of the hard coat layers 2, 2 a, and 2 b and it is easily available. From the viewpoint of increasing the refractive index of the hard coat layers 2, 2 a, 2 b, the coating solution may contain a filler made of zirconia, titania, antimony oxide, or the like. Conversely, from the viewpoint of reducing the refractive index of the hard coat layers 2, 2 a, 2 b, the coating liquid may contain a filler made of a fluoride such as magnesium fluoride and sodium fluoride, a hollow silica filler, and the like. . From the viewpoint of imparting antistatic properties and electrical conductivity to the hard coat layers 2, 2a, 2b, the coating solution may contain a filler made of indium tin oxide (ITO), tin oxide, or the like.

  The surface of the filler may be chemically modified. The specific structure of chemical modification is not limited. As an example, it has an energy polymerizable functional group like a polymerizable compound through a silane coupling agent or the like. In this case, separation between the filler and the polymerizable compound is less likely to occur, and a favorable tendency that the hardness of the hard coat layers 2, 2 a, 2 b is increased and transparency is easily increased is easily observed. In the present specification, silica having an energy polymerizable functional group is referred to as reactive silica, and silica having no energy polymerizable functional group is referred to as non-reactive silica.

  The filler may be spherical or non-spherical. When it is non-spherical, it may be indefinite, or may have a shape with a high aspect ratio such as a needle shape or a scale shape. Since the transparency of the hard coat layer tends to increase, the filler may preferably be spherical.

  The size of the filler is not limited. The average particle size of the filler is usually from about 5 nm to about 2 μm, and the transparency of the hard coat layer is likely to increase. Therefore, the average particle size of the filler may preferably be 5 nm to 100 nm. In addition, let the average particle diameter below 1 micrometer of the filler in this specification be the value measured by the dynamic light-scattering method using the particle size distribution measuring apparatus (The Nikkiso Co., Ltd. make, Nanotrack Wave-UT151). The average particle size of 1 μm or more of the filler is a value measured by a laser diffraction / scattering method using a particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., Microtrac MT3000II).

  The filler content in the coating liquid according to the present embodiment is not limited. What is necessary is just to set suitably so that the hardness of a hard-coat layer, the grade of shrinkage | contraction at the time of forming a hard-coat layer from a coating film, transparency, etc. can be set to a desired range. Illustratively, a specific numerical value range may be 5 to 200 parts by mass with respect to 100 parts by mass of the polymerizable compound, and a preferred range is 10 to 150 parts by mass.

(2-3) Polymerization initiator The coating liquid which concerns on this embodiment contains a polymerization initiator. The kind of polymerization initiator is not limited. The polymerization initiator may be either a photopolymerization initiator or a thermal polymerization initiator, and both may be contained in the coating liquid. By containing a polymerization initiator, it is possible to advance the polymerization reaction of the polymerizable compounds in the coating film by irradiating the coating film of the coating liquid with ultraviolet rays or applying heat to the coating film. It becomes.

  Examples of the photopolymerization initiator include acylphosphine oxide, acetophenone, benzophenone, benzoin, thioxanthone, and imidazole photopolymerization initiators.

  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 the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, diethoxyacetophenone, 2-hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methylpropan-1-one, 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) Phenyl] -1-butanone, benzyldimethyl ketal, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] pheni } -2-methylpropan-1-one, and 2,2-dimethoxy-1,2-and the like.

  Examples of the benzophenone photopolymerization initiator include benzophenone, 4-phenylbenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4,6-trimethylbenzophenone, 4,4′-bis-dimethylaminobenzophenone and the like can be mentioned.

  Examples of the benzoin photopolymerization initiator include benzoin compounds such as benzoin, methylbenzoin, and ethylbenzoin, and benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, and benzoin phenyl ether.

  Examples of the thioxanthone photopolymerization initiator include 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 1-chloro-4-propoxythioxanthone, 2,4-dichlorothioxanthone, and the like.

  Examples of the imidazole photopolymerization initiator include 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbisimidazolyl, 2,2′-bis (o-chlorophenyl)- 4,4 ′, 5,5′-tetra- (p-methoxyphenyl) bisimidazolyl, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2 ′ -Hexaarylbisimidazole compounds such as biimidazole.

  These photopolymerization initiators may be used alone or in combination of two or more.

  Examples of the thermal polymerization initiator include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl). Peroxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, t-hexylperoxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, lauroyl Organic peroxides such as peroxide and diacetyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane- 1-carbonyl), 2,2′-azobis (2,4-dimethylvale) Nitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 4,4′-azobis (4-cyanovale) Rick acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and the like.

  These thermal polymerization initiators may be used alone or in combination of two or more.

  Among these polymerization initiators, a photopolymerization initiator is preferable from the viewpoint of reactivity. Among the photopolymerization initiators, acyl phosphine oxide photopolymerization initiators such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and acetophenone photopolymerization initiators such as 1-hydroxy-cyclohexyl phenyl ketone are preferable.

  The amount of the polymerization initiator used is not particularly limited. Illustratively, a specific numerical value range may be 1 to 15 parts by mass with respect to 100 parts by mass of the polymerizable compound, and a range of 2 to 10 parts by mass is exemplified as a preferred range.

(2-4) Polythiol compound The coating liquid which concerns on this embodiment contains a polythiol compound. A polythiol compound is a compound having two or more mercapto groups in one molecule. Specific examples of polythiol compounds include diglycol dimercaptan, triglycol dimercaptan, tetraglycol dimercaptan, thiodiglycol dimercaptan, thiotriglycol dimercaptan, thiotetraglycol dimercaptan, tris (mercaptopropyl) isocyanurate, ethanedithiol Propanedithiol, hexamethylenedithiol, decamethylenedithiol, tolylene-2,4-dithiol, xylylenedithiol, trimethylolpropane tris-β-mercaptopropionate, o-xylenedithiol, m-xylenedithiol, p-xylenedithiol , Ethylene glycol bisthioglycolate, butanediol bisthioglycolate, hexanediol bisthioglycolate, ethylene Recall bisthiopropionate, butanediol bisthiopropionate, trimethylolpropane tristhiopropionate, pentane erythritol tetrakisthiopropionate, trihydroxyethyl triisocyanuric acid tristhiopropionate, tris [(3- Mercaptopropionyloxy) ethyl] isocyanurate, pentaerythritol tetrakis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), dipentaerythritol hexa (3-mercaptopropionate), diethylene glycol bis ( 3-mercaptopropionate), 1,4-bis (3-mercaptobutyryloxy) butane, 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3 , 5-triazine-2,4,6 (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate), dipentaerythritol hexa (3-mercaptopropionate), and the like.

  Among these, polythiol compounds are tris [(3-mercaptopropionyloxy) ethyl] isocyanurate (TEMPIC), pentaerythritol tetrakis (3-mercaptopropionate) (PEMP), dipentaerythritol hexa (3-mercaptopropio). Nate) (MTPE-1), dipentaerythritol hexa (3-mercaptopropionate) (DPMP), 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2, One or more selected from the group consisting of 4,6- (1H, 3H, 5H) -trione, pentaerythritol tetrakis (3-mercaptobutyrate) and trimethylolpropane tris (3-mercaptopropionate) Preferred to contain There. Since these have three or more mercapto groups in one molecule, the ene-thiol reaction easily proceeds.

  Of the active ingredients contained in the coating liquid, the ingredients that most affect yellowing when the hard coat film 10 comprising the hard coat layers 2, 2a, 2b formed from the coating liquid is heated. Is a polymerization initiator, since the coating liquid according to the present embodiment contains a polythiol compound, the polymerization property contained in the coating liquid even if the content of the polymerization initiator in the coating liquid is reduced. The polymerization reaction of the compound can proceed appropriately. Therefore, the mass ratio of the content of the polymerization initiator to the sum of the content of the polymerizable compound, the content of the filler, and the content of the polythiol compound in the coating liquid according to the present embodiment (in this specification, “start Also referred to as “agent mass ratio”) is preferably 5 mass% or less. Even if the coating liquid according to the present embodiment has an initiator mass ratio of 5% by mass or less, the pencil hardness of the hard coat layers 2, 2a, 2b formed from the coating liquid can be H or more. It is. From the viewpoint of more stably suppressing yellowing of the hard coat layers 2, 2 a, 2 b after heating, the initiator mass ratio of the coating liquid is preferably 3 mass% or less. In this specification, “pencil hardness” indicating the hardness of the hard coat layers 2, 2 a, 2 b is JIS K5600-5-4 (ISO / DIS 15184: 1996, paint general test method—Part 5: coating) Means the pencil hardness measured according to the mechanical properties of the membrane-Section 4: Scratch hardness (pencil method)).

  In the coating liquid according to this embodiment, the mass ratio of the content of the polythiol compound to the sum of the content of the polymerizable compound, the content of the filler, and the content of the polythiol compound (in this specification, “polythiol mass” The ratio is also referred to as 1% by mass or more and less than 30% by mass. From the viewpoint of improving the balance between increasing the hardness of the hard coat layers 2, 2 a, 2 b and making the hard coat layers 2, 2 a, 2 b after heating less susceptible to yellowing, the polythiol mass ratio is 5 The mass is preferably 20% by mass or more and more preferably 5% by mass or more and 15% by mass or less.

  In the coating liquid according to this embodiment, the mass ratio of the filler content relative to the sum of the content of the polymerizable compound, the content of the filler, and the content of the polythiol compound (in this specification, “mass ratio of filler” Is also preferably 5% by mass or more and less than 70% by mass. From the viewpoint of improving the balance between increasing the hardness of the hard coat layer and making it difficult for yellowing to occur in the hard coat layer after heating, the filler mass ratio is 10 mass% or more and 60 mass% or less. Is preferable, and it is more preferable that it is 20 mass% or more and 50 mass% or less.

(2-5) Other components When the polymerization initiator contained in the coating liquid according to the present embodiment is a photopolymerization initiator, the coating liquid according to the present embodiment includes N as well as the photopolymerization initiator. , N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine and other photosensitizers such as triethanolamine are used in combination. May be. These photosensitizers can be used alone or in admixture of two or more.

  The coating liquid according to this embodiment includes the above-described polymerizable compound, filler, polymerization initiator and polythiol compound, and the above-described photosensitizer used as required, and various additives such as an infrared absorber, an oxidation agent, and the like. It can be prepared by adding an inhibitor, a light stabilizer, a leveling agent, an antifoaming agent and the like at a predetermined ratio. At this time, if necessary, a solvent may be added to adjust the concentration and the viscosity suitable for coating.

  Examples of the solvent used in this case include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; methanol, ethanol, propanol, butanol, Examples include alcohols such as 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, methyl isobutyl ketone, and isophorone; esters such as ethyl acetate and butyl acetate; and cellosolv solvents such as ethyl cellosolve.

(2-6) Thickness The thickness of the hard coat layers 2, 2a, 2b is not particularly limited. For example, it is 1 μm or more and 100 μm or less, more preferably 3 μm or more and 60 μm or less, and particularly preferably 5 μm or more and 30 μm or less.

(2-7) Yellowing rate The hard coat film 10 according to the present embodiment is JIS K5600-4-4: 1999 (ISO after heat treatment for holding the hard coat film 10 in an environment of 200 ° C. for 1 hour. The amount of change Δb ^* (= b ^* ₁ -b ^{*) with} respect to the value b ^* ₀ of the color coordinate b ^* of the hard coat film 10 before the heat treatment of the value b ^* ₁ of the color coordinate b ^* defined in 7742-1: 1984) ^. ₀ ) to the total thickness (unit: μm) of the hard coat layer (also referred to as “yellowing rate” in this specification) is less than 0.02 μm ⁻¹ . When the hard coat film 10 has a configuration as shown in FIG. 1, the total thickness of the hard coat layers is equal to the thickness of the hard coat layer 2. When the hard coat film 10 has a configuration as shown in FIG. 2, the total thickness of the hard coat layer is the total thickness of the hard coat layer 2a and the hard coat layer 2b. Since the hard coat film 10 according to this embodiment has a yellowing rate of less than 0.02 μm ⁻¹ , even when the hard coat film 10 is used as a transparent protective member disposed on the display side of the image display device, the image Problems related to display such as color tone change are less likely to occur.

From the viewpoint that the hard coat film 10 according to the present embodiment more stably has suitability as a transparent protective member disposed on the display side of the image display device, the yellowing rate of the hard coat film 10 is 0.015 μm ^−. preferably ¹ or less, more preferably 0.012 .mu.m ^-1 or less.

(2-8) Hardness The hardness of the hard coat layers 2, 2 a, 2 b included in the hard coat film 10 according to the present embodiment is not particularly limited. It should be set as necessary. As an example, the pencil hardness is H or more. If the pencil hardness of the hard coat layers 2, 2 a, 2 b is H or higher, it can be said that the hard coat layer has a sufficiently high hardness. If the pencil hardness of the hard coat layers 2, 2a, 2b is 3H or more, it can be said that the hard coat layer has a particularly high hardness.

(3) Other Elements in Hard Coat Film The hard coat film 10 according to this embodiment may include components other than the base film 1 and the hard coat layers 2, 2 a, 2 b. Specific examples of such elements include a pressure-sensitive adhesive layer and a release sheet.

(3-1) Adhesive layer The hard coat film 10 which concerns on one Embodiment of this invention shown by FIG. 1 has an adhesive layer on the surface on the opposite side to one main surface 1A of the base film 1. FIG. You may have. The hard coat film 10 according to another embodiment of the present invention shown in FIG. 2 may include an adhesive layer on one or both surfaces of the hard coat layers 2a and 2b. The pressure-sensitive adhesive layer provided in the hard coat film 10 according to the present embodiment is a layered body formed from a pressure-sensitive adhesive composition. The composition of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer is not particularly limited. Examples of the pressure-sensitive adhesive that is the main component include rubber-based, acrylic-based, silicone-based, and urethane-based pressure-sensitive adhesives. One type of these may be used, or two or more types may be used.

  The acrylic pressure-sensitive adhesive among the above will be described in more detail. The main component is an acrylic copolymer obtained by copolymerizing a functional group-containing monomer and another monomer such as an acrylic ester or methacrylic ester. And The pressure-sensitive adhesive composition may further contain a cross-linking agent, a tackifier, a filler, an antioxidant, an antistatic agent, an ultraviolet absorber and the like as necessary.

  Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid and methacrylic acid, and hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 4-hydroxybutyl acrylate. . The functional group-containing monomer preferably includes 0.3 to 5.0% by mass as a monomer unit based on the whole monomer constituting the acrylic copolymer (100% by mass). When the acrylic copolymer contains a functional group, the cohesive force can be adjusted by reaction with the crosslinking agent, and the adhesive force and heat resistance can be improved.

  The crosslinking agent used in the pressure-sensitive adhesive composition is not particularly limited and is appropriately selected from those commonly used in pressure-sensitive adhesive compositions mainly composed of acrylic materials. For example, polyisocyanate A compound, an epoxy resin, a melamine resin, a urea resin, a dialdehyde, a methylol polymer, an aziridine compound, a metal chelate compound, a metal alkoxide, a metal salt, or the like is used, and a polyisocyanate compound is preferably used.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited. It should be set appropriately according to the application, and is usually about 1 μm or more and 500 μm or less.

(3-2) Release sheet When the hard coat film 10 according to the present embodiment includes the above-mentioned pressure-sensitive adhesive layer, for the purpose of protecting the surface opposite to the side facing the base film 1 until use. The release surface of the release sheet may be affixed to the surface. As this release sheet, for example, a release treatment comprising applying a release agent to one main surface of a plastic film such as a polyester film such as polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate, or a polyolefin film such as polypropylene or polyethylene. The thing which was given is mentioned. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, and the like can be used, and among these, a silicone-based material that is inexpensive and provides stable performance is preferable. The thickness of the release sheet is not particularly limited.

  The thickness of the release sheet is not limited. Usually, it is about 20-250 micrometers.

2. Manufacturing method of hard coat film The manufacturing method of the hard coat film 10 which concerns on this embodiment is not limited. Hereinafter, an example (first method) of producing the hard coat film 10 shown in FIG. 1 and an example (second method) of producing the hard coat film 10 shown in FIG. 2 will be described.

(1) 1st method (1-1) application process First, the above-mentioned coating liquid is apply | coated on one main surface 1A of the base film 1 with which the hard coat film 10 which concerns on this embodiment is equipped, A coating film is formed on the main surface 1A. The application amount of the coating liquid is not limited. It is appropriately set according to the thickness of the hard coat layers 2, 2a, 2b formed from the coating film obtained by coating. The application method is not particularly limited. Examples thereof include a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method. If necessary, the coating film formed on one main surface 1A of the base film 1 may be dried to remove volatile components, particularly the solvent, contained in the coating film. The conditions for drying are arbitrary, and include, for example, drying at 80 to 140 ° C. for several minutes to several tens of minutes.

(1-2) Curing step The coating film formed on one main surface 1A of the base film 1 by the coating process is contained in the coating film by irradiating energy rays or applying heat thereto. The polymerization reaction of the polymerizable compound is advanced. As the polymerization reaction proceeds, the coating film becomes the hard coat layer 2, and the basic structure of the hard coat film 10 according to the present embodiment including the base film 1 and the hard coat layer 2 is obtained.

  Examples of the energy for advancing the polymerization reaction of the polymerizable compound include heat and energy rays. Examples of the energy rays include ionizing radiation, that is, X-rays, ultraviolet rays, and electron beams. Among these, ultraviolet rays that are relatively easy to introduce irradiation equipment are preferable.

When ultraviolet rays are used as the ionizing radiation, near ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm may be used for ease of handling. The amount of ultraviolet rays may be appropriately selected depending on the thickness of the polymerizable compound of the type and the hard coat layer 2 is usually 50~700mJ / cm ² or so, preferably 200~600mJ / cm ^2, 200~500mJ / Cm ² is more preferable. Moreover, ultraviolet illuminance is about 50-500 mW / cm < ² > normally, 100-450 mW / cm < ² > is preferable and 200-400 mW / cm < ² > is more preferable. There is no restriction | limiting in particular as an ultraviolet-ray source, For example, a high pressure mercury lamp, a metal halide lamp, the light emitting diode (UV-LED) of an ultraviolet region, etc. are used.

(1-3) Pressure-sensitive adhesive layer forming step When the hard coat film 10 is thus obtained, a pressure-sensitive adhesive layer is formed on the main surface opposite to the main surface 1A of the base film 1 as necessary. The formation method of an adhesive layer is arbitrary. For example, a pressure-sensitive adhesive layer-forming coating solution comprising a pressure-sensitive adhesive composition, which is a composition for forming a pressure-sensitive adhesive layer, or a solvent added to the pressure-sensitive adhesive composition as necessary, The pressure-sensitive adhesive layer can be obtained by coating the main surface of the base film 1 opposite to the main surface 1A and drying it. When the pressure-sensitive adhesive composition contains a crosslinking agent, the reaction of the crosslinking agent may be advanced by heating or curing the pressure-sensitive adhesive layer as necessary.

(1-4) Release sheet sticking step When the pressure-sensitive adhesive layer forming step is performed as described above, the exposed surface of the obtained pressure-sensitive adhesive layer, that is, the side facing the base film 1 in the pressure-sensitive adhesive layer. The release surface of the release sheet is affixed to the opposite surface to protect the above surface of the pressure-sensitive adhesive layer.

(2) Second Method The second method is different from the first method in that it includes a step of forming a hard coat layer 2b on the other surface 1B of the base film 1 as well. . The coating process for forming the hard coat layer 2a and the coating process for forming the hard coat layer 2b may be performed simultaneously or separately. The order of performing each coating step in the case of being performed separately is arbitrary.

  Moreover, after forming one hard-coat layer, you may form the coating film which concerns on the other hard-coat layer, and after forming a coating film on both surfaces 1A and 1B of the base film 1, once The hard coat layer 2a and the hard coat layer 2b may be formed by the curing step.

  After the hard coat film 10 having the structure shown in FIG. 2 is obtained, when a pressure-sensitive adhesive layer forming step and, if necessary, a release sheet attaching step are performed, the hardware to be processed in the pressure-sensitive adhesive layer forming step The coat layer may be either the hard coat layer 2a or the hard coat layer 2b, and an adhesive layer or the like may be formed on both the hard coat layers 2a and 2b.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
(1) Preparation of coating solution A coating solution having the following composition was prepared.
i) As a polymerizable compound, 45 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by weight of reactive silica as filler,
iii) 5 parts by mass of tris [(3-mercaptopropionyloxy) ethyl] isocyanurate (TEMPIC) as a polythiol compound,
iv) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.

(2) Production of Hard Coat Film Amount of the above coating solution on both main surfaces of a 25 μm thick base film made of polyethylene terephthalate with a Mayer bar to a thickness of 10 μm as a hard coat layer It was applied and dried in a drying oven at 100 ° C. for 2 minutes to form a coating film on both main surfaces. Using the high-pressure mercury lamp (made by Eye Graphics Co., Ltd., illuminance 200 mW / cm ² ), the irradiation amount is 500 mJ / cm ² with respect to the obtained laminate of the base film and the coating film. Light was irradiated to each main surface of the coating film. In this way, the coating film was cured to provide two hard coat layers having a thickness of 10 μm, and a hard coat film having a total thickness of 20 μm was obtained.

[Example 2]
(1) Preparation of coating solution A coating solution having the following composition was prepared.
i) As a polymerizable compound, 45 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by weight of reactive silica as filler,
iii) 5 parts by mass of pentaerythritol tetrakis (3-mercaptopropionate) (PEMP) as a polythiol compound,
iv) 3 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (“Irgacure (registered trademark) 184” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent.

(2) Production of Hard Coat Film Amount of the above coating liquid on both main surfaces of a 50 μm-thick polyethylene terephthalate base film with a Mayer bar to a thickness of 25 μm as a hard coat layer It was applied to form a coating film on both main surfaces. Using the high-pressure mercury lamp (made by Eye Graphics Co., Ltd., illuminance 200 mW / cm ² ), the irradiation amount is 500 mJ / cm ² with respect to the obtained laminate of the base film and the coating film. Light was irradiated to each main surface of the coating film. In this way, the coating film was cured to obtain two hard coat layers having a thickness of 25 μm, and a total of these thicknesses was 50 μm.

Example 3
A coating solution was prepared in the same manner as in Example 1.
On both main surfaces of a 75 μm-thick polyethylene terephthalate base film, the above-mentioned coating solution is applied with a Mayer bar in an amount so that the thickness as a hard coat layer is 30 μm. A coating was formed on top. Using the high-pressure mercury lamp (made by Eye Graphics Co., Ltd., illuminance 200 mW / cm ² ), the irradiation amount is 500 mJ / cm ² with respect to the obtained laminate of the base film and the coating film. Light was irradiated to each main surface of the coating film. In this way, the coating film was cured, and two hard coat layers having a thickness of 30 μm were provided, and a hard coat film having a total thickness of 60 μm was obtained.

Example 4
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 45 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by mass of non-reactive silica as a filler,
iii) 5 parts by mass of dipentaerythritol hexa (3-mercaptopropionate) (MTPE-1) as a polythiol compound,
iv) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

Example 5
A coating solution having the following composition was prepared.
i) 45 parts by mass of tris (acryloxyethyl) isocyanurate which is a trifunctional acrylate as a polymerizable compound;
ii) 50 parts by weight of reactive silica as filler,
iii) 5 parts by mass of tris [(3-mercaptopropionyloxy) ethyl] isocyanurate (TEMPIC) as a polythiol compound,
iv) 3 parts by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 masses of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

Example 6
A coating solution having the following composition was prepared.
i) 45 parts by mass of a urethane acrylate oligomer as the polymerizable compound,
ii) 50 parts by weight of reactive silica as filler,
iii) 5 parts by mass of dipentaerythritol hexa (3-mercaptopropionate) (MTPE-1) as a polythiol compound,
iv) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

Example 7
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 45 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by weight of reactive silica as filler,
iii) 5 parts by mass of dipentaerythritol hexa (3-mercaptopropionate) (DPMP) as a polythiol compound,
iv) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

Example 8
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 30 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by weight of reactive silica as filler,
iii) 20 parts by mass of tris [(3-mercaptopropionyloxy) ethyl] isocyanurate (TEMPIC) as a polythiol compound,
iv) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

Example 9
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 81 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 10 parts by weight of reactive silica as filler,
iii) 9 parts by mass of dipentaerythritol hexa (3-mercaptopropionate) (MTPE-1) as a polythiol compound,
iv) 1 part by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and v) 10 parts by weight of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

[Comparative Example 1]
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 50 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by weight of reactive silica as filler,
iii) 3 parts by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and iv) 50 masses of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

[Comparative Example 2]
(1) Preparation of coating solution A coating solution having the following composition was prepared.
i) As a polymerizable compound, 50 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 50 parts by mass of non-reactive silica as a filler,
iii) 3 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (“Irgacure (registered trademark) 184” manufactured by BASF) as a photopolymerization initiator, and iv) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent.

(2) Production of Hard Coat Film Amount of the above coating liquid on both main surfaces of a 50 μm-thick polyethylene terephthalate base film with a Mayer bar to a thickness of 25 μm as a hard coat layer It was applied to form a coating film on both main surfaces. Using the high-pressure mercury lamp (made by Eye Graphics Co., Ltd., illuminance 200 mW / cm ² ), the irradiation amount is 500 mJ / cm ² with respect to the obtained laminate of the base film and the coating film. Light was irradiated to each main surface of the coating film. In this way, the coating film was cured to obtain a hard coat film having two hard coat layers having a thickness of 25 μm and a total thickness of 50 μm.

[Comparative Example 3]
10 μm thickness on each surface of the 25 μm-thick base film in the same manner as in Comparative Example 1 except that the blending amount of the photopolymerization initiator was changed to 1 part by mass in the preparation of the coating liquid. A hard coat film having a total thickness of 20 μm was obtained.

[Comparative Example 4]
A coating solution having the following composition was prepared.
i) As a polymerizable compound, 90 parts by mass of dipentaerythritol hexaacrylate (DPHA), which is a hexafunctional acrylate,
ii) 10 parts by mass of dipentaerythritol hexa (3-mercaptopropionate) (MTPE-1) as a polythiol compound,
iii) 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide (“Irgacure (registered trademark) TPO” manufactured by BASF) as a photopolymerization initiator, and iv) 50 parts by mass of methyl isobutyl ketone (MIBK) as a solvent Department.
Hereinafter, in the same manner as in Example 1, a hard coat film having a 10 μm thick hard coat layer on each surface of a 25 μm thick base film and a total thickness of the hard coat layer of 20 μm was obtained. .

[Test Example 1] <Measurement of yellowing rate>
About each of the hard coat film manufactured by the Example and the comparative example, the value b ^* ₀ of the color coordinate b ^* prescribed | regulated to JISK5600-4-4: 1999 (ISO 7724-1: 1984) was measured. Each hard coat film was heat-treated for 1 hour in an environment of 200 ° C. The value b ^* ₁ of the color coordinate b ^* was measured for the hard coat film after the heat treatment. The yellowing rate of each hard coat film was determined by dividing the change amount Δb ^* (= b ^* _1- b ^* ₀ ) of the color coordinate b ^* by the total thickness (unit: μm) of the hard coat layer. The results are shown in Table 1.

[Test Example 2] <Pencil hardness>
Examples and comparative examples based on JIS K5600-5-4 (ISO / DIS 15184: 1996, paint general test method-Part 5: Mechanical properties of coating film-Section 4: Scratch hardness (pencil method)) The pencil hardness of the hard coat layer was determined for each of the hard coat films produced by the above method. The results are shown in Table 1.

  As can be seen from Table 1, the hard coat layer included in the hard coat film of the example satisfying the conditions of the present invention had a sufficiently high hardness of 2H or more, and yellowing did not easily occur even when heated.

  The hard coat film according to the present invention is suitably used as a transparent protective member on the display side of the image display device.

DESCRIPTION OF SYMBOLS 10 ... Hard coat film 1 ... Base film 1A ... One main surface 2, 2a, 2b of a base film ... Hard coat layer 1B ... The other main surface of a base film

Claims (7)

A hard coat film comprising a base film and a hard coat layer laminated on at least one surface of the base film,
The hard coat layer is formed from a coating liquid containing a compound having an energy polymerizable functional group, a filler, a polymerization initiator, and a polythiol compound,
The value b ^* _{1 of the} color coordinate b ^* defined in JIS K5600-4-4: 1999 (ISO 7724-1: 1984) after the heat treatment of holding the hard coat film in an environment of 200 ° C. for 1 hour. The ratio of the amount of change Δb ^* with respect to the value b ^* ₀ of the color coordinate b ^* before heat treatment of the hard coat film of the hard coat film to the total thickness of the hard coat layer is less than 0.02 μm ^−1. Hard coat film.   The hard coat film according to claim 1, wherein the total thickness of the hard coat layers is 5 μm or more.   In the coating liquid, the mass ratio of the content of the polymerization initiator to the total content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound is: The hard coat film according to claim 1 or 2 which is 5 mass% or less.   The mass ratio of the content of the polythiol compound to the sum of the content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound in the coating liquid is 1 The hard coat film according to any one of claims 1 to 3, wherein the hard coat film is not less than 30% by mass and not more than 30% by mass.   The mass ratio of the filler content to the sum of the content of the compound having the energy polymerizable functional group, the content of the filler, and the content of the polythiol compound in the coating liquid is 5 mass. The hard coat film according to claim 1, wherein the hard coat film is not less than 70% and not more than 70% by mass.   The hard coat film according to any one of claims 1 to 5, wherein the pencil hardness is H or more.   The coating liquid for forming the hard-coat layer with which the hard-coat film as described in any one of Claims 1-6 is provided on at least one surface of a base film is coated on the said base film. A method for producing a hard coat film, comprising forming a film and irradiating the coating film with energy to form a hard coat layer on the substrate film.

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