JP2015212842A - Hard coat film, and method for producing hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a hard coat film which has high surface hardness and can suppress curling.SOLUTION: A method for producing a hard coat film includes: a step (A) of applying a curable material capable of being cured by heat onto a surface 11 of a substrate 10 formed of a thermoplastic resin to form a coating layer 12; and a step (B) of curing the coating layer 12 to obtain a hard coat layer. The step (B) includes a step (b1) of heating a surface part 13 of the coating layer 12 at a higher temperature than those of a part 14 other than the surface part of the coating layer 12, and the substrate 10 to cure the surface part 13. A difference (Th1-Ts) between a maximum heating temperature Th1 of the coating layer 12 in the step (b1) and a Vicat softening temperature Ts of the thermoplastic resin is greater than -20°C.

Description

  The present invention relates to a hard coat film and a method for producing the same.

  In order to protect the display surface of a display device such as a liquid crystal display device, a hard coat film may be provided on the surface of the display surface. The hard coat film is a film having a high surface hardness. By providing the hard coat film so as to cover the display surface, it is possible to prevent the display surface from being damaged. As such a hard coat film, for example, a film in which a hard hard coat layer is formed on the surface of a film-like substrate is used (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2005-288921

  The hard coat layer may be formed of a curable resin. For example, a hard coat layer is formed on the surface of the base material by applying an uncured resin to the surface of the base material and curing the applied resin. However, since the resin generally shrinks when the resin is cured, a stress that tends to shrink (hereinafter referred to as “shrinking force” as appropriate) occurs in the hard coat layer, and the obtained hard coat film may curl. there were. The higher the hardness of the hard coat layer, the more the resin tends to shrink. Therefore, it has been difficult to achieve both the increase in the hardness of the hard coat layer and the curling of the hard coat film.

  In order to solve such problems, Patent Document 1 proposes a technique for keeping the volume shrinkage of the resin that is the main component of the hard coat layer and the thickness of the hard coat layer within a predetermined range. . However, in the technique described in Patent Document 1, the type of resin that is the main component of the hard coat layer and the thickness of the hard coat layer are limited. Therefore, in order to increase the degree of design freedom, it has been desired to develop a new technology that can achieve both improvement of the surface hardness of the hard coat film and suppression of curling.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a hard coat film having a high surface hardness and capable of suppressing curling, and a method for producing the hard coat film.

As a result of intensive studies to solve the above problems, the present inventors applied a curable material that can be cured by heat to the surface of the base material to form an application layer, and then cured the application layer to form a hard coat layer. A method for producing a hard coat film to be formed, wherein a hard coat film having a high surface hardness is obtained by heating a surface portion of a coating layer to a higher temperature than other portions to selectively cure the surface portion. I found out that Further, in the hard coat film manufactured in this way, the surface portion of the hard coat layer has a large degree of shrinkage, but the degree of shrinkage other than the surface portion of the hard coat layer is small, so the hard coat layer as a whole shrinks. It has been found that the force is reduced and curling of the hard coat film can be suppressed. Furthermore, in such a manufacturing method, since it is not necessary to heat a base material to high temperature, even if it uses the material which is easy to deteriorate or deform | transform by heat as a material of a base material, the quality of the hard coat film manufactured does not fall. I found out. The present inventor completed the present invention based on the above findings.
That is, the gist of the present invention is the following [1] to [19].

[1] A step (A) of forming a coating layer by applying a curable material that can be cured by heat to the surface of a base material made of a thermoplastic resin, and a step of curing the coating layer to obtain a hard coat layer (B)
The step (B) includes a step (b1) of curing the surface portion of the coating layer by heating to a temperature higher than the portion other than the surface portion of the coating layer and the base material,
The method for producing a hard coat film, wherein a difference Th1-Ts between a maximum heating temperature Th1 of the coating layer in the step (b1) and a Vicat softening temperature Ts of the thermoplastic resin is larger than −20 ° C.
[2] The hard coat according to [1], wherein in the step (B), the volume shrinkage ratio of the surface portion of the hard coat layer is larger than the volume shrinkage rate of a portion other than the surface portion of the hard coat layer. A method for producing a film.
[3] The method for producing a hard coat film according to [1] or [2], wherein the volume shrinkage ratio of the surface of the hard coat layer in the step (B) is 10% to 50%.
[4] The step (B) includes a step (b2) of heating a portion other than the surface portion of the coating layer at a temperature lower than a temperature of heating the surface portion of the coating layer in the step (b1). , [1] to [3] The method for producing a hard coat film according to any one of [1] to [3].
[5] The method for producing a hard coat film according to any one of [1] to [4], wherein the heating in the step (b1) is performed using a flash lamp annealing apparatus.
[6] The hard coat according to any one of [1] to [5], wherein the surface portion of the coating layer is a portion from the surface of the coating layer to 2/3 or less of the thickness of the coating layer. A method for producing a film.
[7] The method for producing a hard coat film according to any one of [1] to [6], wherein the hard coat layer is a single layer.
[8] The method for producing a hard coat film according to any one of [1] to [7], wherein the thermoplastic resin has a Vicat softening temperature of 135 ° C. or lower.
[9] The method for producing a hard coat film according to any one of [1] to [8], wherein the curable material can be cured by active energy rays.
[10] The degree of increase in haze of the base material after obtaining the hard coat layer in the step (B) compared to before performing the step (A) is 0.5% or less, [1] -The manufacturing method of the hard coat film as described in any one of [9].
[11] Any of [1] to [10], wherein the thermoplastic resin is one or more resins selected from the group consisting of alicyclic structure-containing polymer resins, polycarbonate resins, cellulose ester resins, and acrylic resins. The method for producing a hard coat film according to claim 1.
[12] A hard coat film produced by the production method according to any one of [1] to [11].
[13] The hard coat film according to [12], wherein the surface of the hard coat layer has a hardness of H or more.
[14] The hard coat film according to [12] or [13], wherein the curl height of the hard coat film is 20 mm or less.
[15] The hard coat film according to any one of [12] to [14], wherein the thickness of the hard coat layer is 30 μm or less.
[16] The hard coat film according to any one of [12] to [15], wherein the substrate has a hardness of B or less.
[17] The hard coat film according to any one of [12] to [16], wherein the substrate has a retardation.
[18] The hard coat film according to [17], wherein the base material is obliquely stretched.
[19] A base material, and a single-layer hard coat layer formed of a resin on the surface of the base material,
A hard coat film, wherein a hardness of a surface portion of the hard coat layer opposite to the substrate is larger than a hardness of an interface portion of the hard coat layer with the base material.

According to the method for producing a hard coat film of the present invention, a hard coat film having a high surface hardness and capable of suppressing curling can be produced.
The hard coat film of the present invention has a high surface hardness and can suppress curling.

FIG. 1 is a cross-sectional view schematically showing how the coating layer is cured in step (B). FIG. 2 is a cross-sectional view schematically showing an example of the configuration of the flash lamp annealing apparatus.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the following embodiments and examples, and departs from the gist of the present invention and its equivalent scope. You may change arbitrarily and implement in the range which does not. In the following description, the symbols (A), (B), (b1), and (b2) of the step (A), the step (B), the step (b1), and the step (b2) It is the code | symbol for distinguishing the attached element from the other elements, and has no meaning other than the distinction of an element.

[1. Overview〕
The method for producing a hard coat film of the present invention (hereinafter referred to as “the method of production of the present invention” as appropriate) comprises applying a curable material that can be cured by heat onto the surface of a base material made of a thermoplastic resin. A step (A) of forming a coating layer and a step (B) of obtaining a hard coat layer by curing the coating layer.

  FIG. 1 is a cross-sectional view schematically showing how the coating layer is cured in step (B). As shown in FIG. 1, in the step (B), the surface portion 13 of the coating layer 12 formed on the surface 11 of the substrate 10 is heated to a temperature higher than the portion 14 other than the surface portion of the coating layer 12 and the substrate 10. A step (b1) of heating and curing. By performing this step (b1), the surface portion 13 of the coating layer 12 is hardened, so that the hardness of the surface 15 can be increased. Further, in the step (b1), the surface portion 13 of the coating layer 12 is hardened and the degree of shrinkage is increased, but the portion 14 other than the surface portion of the coating layer 12 is not as hot as the surface portion 13, so The degree is small. Accordingly, since the coating layer 12 as a whole does not generate a large shrinkage force, curling of the obtained hard coat film can be suppressed.

[2. Step (A)]
In the method for producing a hard coat film of the present invention, the step (A) of forming a coating layer by applying a curable material that can be cured by heat to the surface of a substrate made of a thermoplastic resin is performed.

[2-1. Base material〕
The base material is a film formed of a thermoplastic resin. In this case, one kind of thermoplastic resin may be used alone, or two or more kinds may be used in combination at any ratio.
As the kind of the thermoplastic resin, it is preferable to select an appropriate resin according to the optical characteristics required for the hard coat film. Among these, an amorphous resin is preferable, and an alicyclic structure-containing polymer resin, a polycarbonate resin, a cellulose ester resin, and an acrylic resin are preferable because they are excellent in stretch processability and dimensional stability.

-Alicyclic structure containing polymer resin An alicyclic structure containing polymer resin is resin containing an alicyclic structure containing polymer. At this time, one type of alicyclic structure-containing polymer may be used alone, or two or more types may be used in combination at any ratio.

  The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the repeating unit of the polymer, and has a polymer having an alicyclic structure in the main chain and an alicyclic structure in the side chain. Any of the polymers may be used. Among these, a polymer containing an alicyclic structure in the main chain is preferable from the viewpoint of mechanical strength, heat resistance, and the like.

  Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among these, from the viewpoints of mechanical strength, heat resistance and the like, a cycloalkane structure and a cycloalkene structure are preferable, and a cycloalkane structure is particularly preferable.

  The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly preferably per alicyclic structure. Is in the range of 15 or less, the mechanical strength, heat resistance, and moldability of the substrate are highly balanced, which is preferable.

  The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer may be appropriately selected according to the purpose of use, but is preferably 55% by weight or more, more preferably 70% by weight or more. Particularly preferably, it is 90% by weight or more. When the ratio of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer is in this range, it is preferable from the viewpoint of the transparency and heat resistance of the hard coat film.

  Examples of alicyclic structure-containing polymers include norbornene polymers, monocyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and hydrides thereof. Can be mentioned. Among these, norbornene-based polymers can be suitably used because of their good transparency and moldability.

  As the norbornene-based polymer, for example, a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; An addition polymer of a monomer having a norbornene structure, an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used. The “(co) polymer” means a polymer and a copolymer.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ^2,5 ] deca-3,7. -Diene (common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4. 0.1 ^2,5 . ^{17, 10} ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different, and a plurality thereof may be bonded to the ring. In addition, the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfonic acid group.

  Other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include, for example, monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; and cyclic conjugates such as cyclohexadiene and cycloheptadiene. Dienes and derivatives thereof; and the like. In addition, the monomer which has a norbornene structure and the other monomer which can carry out ring-opening copolymerization may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer with another monomer copolymerizable with a monomer having a norbornene structure are, for example, a known ring-opening monomer. It can be obtained by polymerization or copolymerization in the presence of a polymerization catalyst.

  Examples of the other monomer capable of addition copolymerization with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene and 1-butene, and derivatives thereof; cyclobutene and cyclopentene. And cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene; and the like. Among these, α-olefin is preferable and ethylene is more preferable. In addition, the other monomer which can carry out addition copolymerization with the monomer which has a norbornene structure may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with the monomer having a norbornene structure are, for example, a known addition polymerization catalyst. It can be obtained by polymerization or copolymerization in the presence.

  Examples of the monocyclic olefin polymer include addition polymers of a cyclic olefin monomer having a single ring such as cyclohexene, cycloheptene, and cyclooctene.

  Examples of the cyclic conjugated diene polymer include polymers obtained by cyclization reaction of addition polymers of conjugated diene monomers such as 1,3-butadiene, isoprene and chloroprene; cyclic conjugates such as cyclopentadiene and cyclohexadiene. And 1,2- or 1,4-addition polymers of diene monomers; and their hydrides.

  Examples of vinyl alicyclic hydrocarbon polymers include polymers of vinyl alicyclic hydrocarbon monomers such as vinylcyclohexene and vinylcyclohexane and their hydrides; vinyl aromatic hydrocarbons such as styrene and α-methylstyrene. Hydrogenated product obtained by hydrogenating an aromatic ring part contained in a polymer obtained by polymerizing monomers; vinyl alicyclic hydrocarbon monomer, or vinyl aromatic hydrocarbon monomer and vinyl aromatic hydrocarbon monomer And an aromatic ring hydride of a copolymer such as a random copolymer or a block copolymer with another copolymerizable monomer. Examples of the block copolymer include a diblock copolymer, a triblock copolymer or higher multiblock copolymer, and a gradient block copolymer.

  The alicyclic structure-containing polymer resin may contain other components in addition to the alicyclic structure-containing polymer as long as the effects of the present invention are not significantly impaired. Examples of other components include: lubricants; layered crystal compounds; inorganic fine particles; stabilizers such as antioxidants, heat stabilizers, light stabilizers, weathering stabilizers, ultraviolet absorbers, near infrared absorbers; plasticizers; And coloring agents such as dyes and pigments; antistatic agents; and the like. Among these, a lubricant and an ultraviolet absorber are preferable because they can improve flexibility and weather resistance. In addition, one type of other components may be used alone, or two or more types may be used in combination at any ratio. Further, the amount of other components can be appropriately determined within a range that does not significantly impair the effects of the present invention. For example, if the total light transmittance in terms of 1 mm thickness of the substrate can be maintained at 80% or more, Good.

  Examples of the lubricant include inorganic particles such as silicon dioxide, titanium dioxide, magnesium oxide, calcium carbonate, magnesium carbonate, barium sulfate, strontium sulfate; polymethyl acrylate, polymethyl methacrylate, polyacrylonitrile, polystyrene, cellulose acetate, cellulose acetate pro Organic particles such as pionate can be mentioned. Among these, organic particles are preferable as the lubricant.

  Examples of ultraviolet absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, acrylonitrile ultraviolet absorbers, triazine compounds, nickel complex compounds. And inorganic powders. Specific examples of suitable UV absorbers include 2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) ) Phenol, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, and the like. Particularly preferred are 2,2′-methylenebis ( 4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol).

-Polycarbonate resin Polycarbonate resin is resin containing a polycarbonate. Under the present circumstances, a polycarbonate may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  As the polycarbonate, any polymer can be used as long as it is a polymer having a repeating unit (hereinafter referred to as “carbonate component” as appropriate) based on a carbonate bond (—O—C (═O) —O—). Moreover, what consists of one type of repeating unit may be used for a polycarbonate, and what combined two or more types of repeating units in arbitrary ratios may be used. Further, the polycarbonate may be a copolymer having a repeating unit other than the carbonate component. However, even when the polycarbonate has a repeating unit other than the carbonate component, the content of the carbonate component contained in the polycarbonate is preferably high. Specifically, the content is preferably 80% by weight or more, and more preferably 85% by weight or more.

  Examples of the polycarbonate include bisphenol A polycarbonate, branched bisphenol A polycarbonate, o, o, o ', o'-tetramethylbisphenol A polycarbonate, and the like.

  Further, the polycarbonate resin may contain other components in addition to the polycarbonate as long as the effects of the present invention are not significantly impaired. Examples and amounts of other components are the same as those of other components that the alicyclic structure-containing polymer resin may contain. In addition, one type of other components may be used alone, or two or more types may be used in combination at any ratio.

-Cellulose ester resin Cellulose ester resin is resin containing cellulose ester. Under the present circumstances, cellulose ester may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The cellulose ester is preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. Examples of lower fatty acid esters of cellulose include cellulose acetate, cellulose propionate, and cellulose butyrate. Examples of the lower fatty acid ester of cellulose include cellulose acetate pro as described in JP-A-10-45804, JP-A-8-2311761, U.S. Pat. No. 2,319,052. Examples thereof include mixed fatty acid esters such as pionate and cellulose acetate butyrate. Among these, cellulose triacetate and cellulose acetate propionate are particularly preferable.

  In addition, the cellulose ester resin may contain other components in addition to the cellulose ester as long as the effects of the present invention are not significantly impaired. Examples and amounts of other components are the same as those of other components that the alicyclic structure-containing polymer resin may contain. In addition, one type of other components may be used alone, or two or more types may be used in combination at any ratio.

-Acrylic resin An acrylic resin is resin containing an acrylic polymer. In this case, one kind of acrylic polymer may be used alone, or two or more kinds thereof may be used in combination at any ratio.

  The acrylic polymer means a polymer of acrylic acid or an acrylic acid derivative, and examples thereof include polymers and copolymers such as acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid and methacrylic ester. Since the acrylic polymer has high strength and is hard, a hard coat film having high strength can be realized.

  As the acrylic polymer, a polymer containing a repeating unit derived from a (meth) acrylic acid ester is preferable. Here, “(meth) acrylic acid” means acrylic acid and methacrylic acid.

  Examples of (meth) acrylic acid esters include alkyl esters of (meth) acrylic acid. Especially, the thing derived from (meth) acrylic acid and a C1-C15 alkanol or cycloalkanol is preferable, and the thing derived from a C1-C8 alkanol is more preferable. By reducing the number of carbon atoms as described above, the elongation at break of the substrate can be reduced.

  Specific examples of the acrylate ester include methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, sec-butyl acrylate, and t-acrylate. -Butyl, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl acrylate, n-dodecyl acrylate, and the like.

  Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, sec-butyl methacrylate, methacrylic acid. Examples thereof include t-butyl acid, n-hexyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, n-decyl methacrylate, and n-dodecyl methacrylate.

Furthermore, the (meth) acrylic acid ester may have a substituent such as a hydroxyl group or a halogen atom as long as the effects of the present invention are not significantly impaired. Examples of the (meth) acrylic acid ester having such a substituent include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylic acid 2- Examples include hydroxypropyl, 4-hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, and glycidyl methacrylate.
In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The acrylic polymer may be a polymer of acrylic acid or an acrylic acid derivative alone, but may be a copolymer of acrylic acid or an acrylic acid derivative and a monomer copolymerizable therewith. Examples of the copolymerizable monomer include α, β-ethylenically unsaturated carboxylic acid ester monomers other than the above-mentioned (meth) acrylic acid esters, and α, β-ethylenically unsaturated carboxylic acid monomers. Examples include a monomer, an alkenyl aromatic monomer, a conjugated diene monomer, a non-conjugated diene monomer, a carboxylic acid unsaturated alcohol ester, and an olefin monomer. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  Specific examples of α, β-ethylenically unsaturated carboxylic acid ester monomers other than (meth) acrylic acid esters include dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, and dimethyl itaconate. It is done.

  The α, β-ethylenically unsaturated carboxylic acid monomer may be any of a monocarboxylic acid, a polyvalent carboxylic acid, a partial ester of a polyvalent carboxylic acid, and a polyvalent carboxylic acid anhydride. Specific examples thereof include crotonic acid, maleic acid, fumaric acid, itaconic acid, monoethyl maleate, mono n-butyl fumarate, maleic anhydride, itaconic anhydride and the like.

  Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyl toluene and divinylbenzene.

  Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1. , 3-butadiene, cyclopentadiene and the like.

  Specific examples of the non-conjugated diene monomer include 1,4-hexadiene, dicyclopentadiene, ethylidene norbornene and the like.

  Specific examples of the carboxylic acid unsaturated alcohol ester monomer include vinyl acetate.

  Specific examples of the olefin monomer include ethylene, propylene, butene, pentene and the like.

  When the acrylic polymer contains a copolymerizable monomer, the content of the repeating unit derived from the monomer copolymerizable with acrylic acid or an acrylic acid derivative in the acrylic polymer is preferably 50% by weight or less. More preferably, it is 15% by weight or less, particularly preferably 10% by weight or less.

  Of these acrylic polymers, polymethacrylate is preferred, and polymethyl methacrylate is more preferred.

  The acrylic resin may contain other components in addition to the acrylic polymer as long as the effects of the present invention are not significantly impaired. Examples and amounts of other components are the same as those of other components that the alicyclic structure-containing polymer resin may contain. In addition, one type of other components may be used alone, or two or more types may be used in combination at any ratio.

-Physical property etc. of thermoplastic resin The glass transition temperature Tg of a thermoplastic resin is 90 degreeC or more normally, Preferably it is 100 degreeC or more, More preferably, it is 120 degreeC or more. By increasing the glass transition temperature Tg in this way, it is possible to prevent the relaxation of the orientation of the substrate in a high temperature environment and improve the durability. However, if the glass transition temperature Tg of the thermoplastic resin is excessively high, the stretching treatment may be difficult. Therefore, the glass transition temperature Tg of the thermoplastic resin is usually 300 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower.

  The Vicat softening temperature of the thermoplastic resin is usually 300 ° C. or lower, preferably 200 ° C. or lower, more preferably 135 ° C. or lower. When the Vicat softening temperature is so low, the substrate may be deformed when the entire film including the substrate and the coating layer is heated to cure the coating layer as in the case of a conventional hard coat film. . However, in the manufacturing method of the present invention, when the coating layer is cured to increase the surface hardness, the surface portion of the coating layer is selectively heated, so that no great heat is applied to the substrate. For this reason, even if it is a base material which consists of a thermoplastic resin with a low Vicat softening temperature as mentioned above, it can avoid deform | transforming. Therefore, in the production method of the present invention, a thermoplastic resin having a low Vicat softening temperature, which has been difficult to use in the past, can be used, so that the advantage of the present invention that the degree of freedom of selection of the resin can be increased effectively. From the viewpoint of utilization, it is preferable. In addition, although there is no restriction | limiting in the minimum of the Vicat softening temperature of a thermoplastic resin, from a heat resistant viewpoint of the hard coat film of this invention, it is 80 degreeC or more normally, Preferably it is 90 degreeC or more, More preferably, it is 100 degreeC or more. .

-Layer structure of base material The base material may be a single-layer film having only one layer, or may be a multilayer film having two or more layers.

-Physical properties of base material The hardness of the base material is preferably H or less, preferably B or less, and more preferably 2B or less. Even if the hardness of the substrate is so low, the hardness of the surface portion of the hard coat layer is high, so that the surface hardness of the hard coat film of the present invention can be increased. Further, when the hardness of the base material is low, curling is likely to occur in the conventional hard coat film, but the hard coat film of the present invention can suppress curling even when the base material having such low hardness is used. Therefore, it is preferable to use a substrate having a low hardness from the viewpoint of effectively utilizing the advantages of the present invention.
In addition, the said hardness is the pencil hardness measured with a 500-g load according to JIS-5600-5-4.

  The base material may have a phase difference. Usually, in the manufacturing method of the present invention, the phase difference of the base material does not change in the step (B), so the base material of the hard coat film to be manufactured also has the same phase difference as the base material before the step (A). . Further, even if the hard coat layer has no retardation or not, the absolute value of the retardation is often small. Therefore, the retardation of the base material is usually the retardation of the entire hard coat film. The specific retardation range is set according to the use of the hard coat film. The in-plane retardation Re of the substrate is usually 10 nm to 500 nm, and the retardation Rth in the thickness direction of the substrate is −500 nm to 500 nm. .

  The in-plane retardation Re is the refractive index nx in the slow axis direction of the substrate, the refractive index ny in the direction perpendicular to the slow axis in the plane, the refractive index nz in the thickness direction, and the average thickness D of the substrate. Is a value defined by (nx−ny) × D. The retardation in the thickness direction is a value defined by ((nx + ny) / 2−nz) × D.

  Furthermore, in the production method of the present invention, optical properties such as transparency and light scattering properties of the substrate are hardly changed in the step (B). Therefore, it is preferable to set the optical properties such as transparency and light scattering property of the substrate to be the same as the hard coat film to be manufactured.

  The thickness of the substrate is usually 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and usually 250 μm or less, preferably 100 μm or less, more preferably 40 μm or less. In general, a hard coat film having such a thin substrate is likely to curl. However, according to the production method of the present invention, curling can be suppressed even in a hard coat film having a thin substrate as described above. it can.

-Base material manufacturing method Examples of the base material manufacturing method include a cast molding method, an extrusion molding method, an inflation molding method, and the like. Especially, the melt extrusion method which does not use a solvent can reduce the amount of residual volatile components efficiently, and is preferable from a viewpoint of the viewpoint of global environment or work environment, and a manufacturing efficiency. Examples of the melt extrusion method include an inflation method using a die, and a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

  Examples of the method for producing a multilayer substrate include coextrusion T-die method, coextrusion inflation method, coextrusion lamination method and the like; film lamination molding method such as dry lamination; co-casting And a coating molding method such as coating a resin solution on the surface of the resin film. Among these, the co-extrusion molding method is preferable from the viewpoint of manufacturing efficiency and preventing a volatile component such as a solvent from remaining in the film. Examples of the co-extrusion molding method include a co-extrusion T-die method, a co-extrusion inflation method, and a co-extrusion lamination method, and among them, the co-extrusion T-die method is preferable. Further, the coextrusion T-die method includes a feed block method and a multi-manifold method, but the multi-manifold method is particularly preferable in that variation in thickness can be reduced.

  When a base material has a phase difference, the base material obtained with the manufacturing method mentioned above is extended | stretched, for example. By stretching, the molecules contained in the base material are oriented, so that a phase difference can be expressed in the base material. The film obtained by performing the stretching treatment in this manner is appropriately referred to as “stretched film”. The magnitude of the phase difference and the direction of the slow axis are affected by the type of thermoplastic resin, so when the substrate has a phase difference, it is suitable for the development of the desired phase difference as a thermoplastic resin. For example, it is preferable to use one or more resins selected from the group consisting of alicyclic structure-containing polymer resins, polycarbonate resins, and cellulose ester resins.

  The stretching method is not particularly limited, and for example, either a uniaxial stretching method or a biaxial stretching method may be adopted. As an example of the stretching method, as an example of the uniaxial stretching method, a method of uniaxial stretching in the longitudinal direction using a difference in peripheral speed of a roll for film conveyance; uniaxial stretching in the width direction using a tenter stretching machine And the like. In addition, as an example of the biaxial stretching method, simultaneous biaxial stretching method that stretches in the width direction according to the spread angle of the guide rail at the same time as stretching in the longitudinal direction with an interval between the clips to be fixed; roll for film conveyance The biaxial stretching method such as the sequential biaxial stretching method is used in which the two ends are clipped and stretched in the width direction using a tenter stretching machine. Can be mentioned. Further, for example, by using a tenter stretching machine that can add a feeding force, a pulling force, or a pulling force at different speeds in the width direction or the longitudinal direction, an arbitrary angle θ (0 An oblique stretching method may be used in which oblique stretching is continuously performed in a direction satisfying ° <θ <90 °. Among these stretching methods, an oblique stretching method is preferable, and an oblique stretching method in which stretching is performed in a direction that forms an angle of 45 ° ± 5 ° with respect to the width direction of the film is particularly preferable.

Examples of the apparatus used for stretching include a longitudinal uniaxial stretching machine, a tenter stretching machine, a bubble stretching machine, and a roller stretching machine.
The temperature during stretching is preferably (Tg-30 ° C) or higher, more preferably (Tg-10 ° C) or higher, preferably (Tg + 60 ° C) or lower, based on the glass transition temperature Tg of the thermoplastic resin. Preferably, it is (Tg + 50 ° C.) or less. In addition, when a base material is a multilayer film, the glass transition temperature Tg of a thermoplastic resin may change with layers. In that case, the temperature during stretching is preferably set based on the glass transition temperature Tg of the thermoplastic resin forming the layer having the lowest glass transition temperature Tg.

  The draw ratio may be appropriately selected according to optical properties such as retardation to be developed on the substrate and the hard coat film, and is usually 1.05 times or more, preferably 1.1 times or more, and usually 10 0.0 times or less, preferably 2.0 times or less.

  Furthermore, the substrate may be subjected to a surface treatment in order to improve the adhesion with the hard coat layer. Examples of the surface treatment include plasma treatment, corona treatment, and alkali treatment. Among these, the corona treatment is preferable because the adhesiveness can be particularly improved.

[2-2. (Curable material)
As the curable material, a material that can be cured by heat is used. Further, the curable material is required to have a desired hardness after curing and to have transparency according to the use of the hard coat film. Furthermore, from the viewpoint of easy application to the surface of the substrate, the curable material is usually prepared as a liquid material before application. As the curable material, for example, a thermosetting resin is used.

  Examples of thermosetting resins include phenolic resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, unsaturated polyester resins, polyurethane resins, epoxy resins, thermosetting acrylic resins, urethane acrylic resins, amino alkyd resins. Melamine urea co-condensation resin, silicon resin, polysiloxane resin and the like. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

Among the curable materials, those that can be cured by active energy rays are preferable. It is for making it harden | cure an application layer reliably by using a heat | fever and an active energy ray together in a process (B). Here, the active energy rays refer to, for example, visible light, ultraviolet rays, electron beams and the like.
When the example of the curable material which can be hardened | cured with an active energy ray is given, a melamine resin, an epoxy resin, a photocurable acrylic resin, a urethane acrylic resin etc. will be mentioned. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

Furthermore, the curable material may contain fine particles as necessary. By including the fine particles, the conductivity and refractive index of the hard coat layer can be adjusted.
The fine particles may be organic fine particles, inorganic fine particles, or a combination of organic fine particles and inorganic fine particles. Examples of fine particle materials include silica, titania (titanium oxide), zirconia (zirconium oxide), zinc oxide, tin oxide, cerium oxide, antimony pentoxide, titanium dioxide, tin-doped indium oxide (ITO), antimony Doped tin oxide (ATO), phosphorus doped tin oxide (PTO), zinc doped indium oxide (IZO), aluminum doped zinc oxide (AZO), fluorine doped tin oxide (FTO), etc. Can be mentioned. Among these, silica is suitable as a component for adjusting the refractive index because it is excellent in the balance between adhesion to the substrate and transparency. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  The number average particle diameter of the fine particles is usually 1 nm or more, usually 1000 nm or less, preferably 500 nm or less, more preferably 250 nm or less. Usually, the smaller the particle size, the lower the haze of the hard coat layer and the better the adhesion between the substrate and the hard coat layer.

  The amount of the fine particles is usually 10 parts by weight or more, preferably 20 parts by weight or more, and usually 80 parts by weight or less, preferably 50 parts by weight or less, more preferably 40 parts by weight or less with respect to 100 parts by weight of the curable material. It is. By setting the amount of fine particles in the above range, a hard coat film excellent in optical characteristics such as haze and total light transmittance can be produced.

  The curable material may contain a solvent as necessary. By including the solvent, the viscosity of the curable material can be adjusted to improve the coating property. The solvent usually vaporizes quickly after the curable material is applied to the surface of the substrate. For this reason, the coating layer formed on the surface of the substrate usually does not contain a solvent.

  Examples of solvents include alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol; ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, diethylene glycol, diethylene glycol monobutyl ether, diacetone glycol, etc. Glycols; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; oximes such as methyl ethyl ketoxime; In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The curable material may contain a polymerization initiator as necessary. Usually, a thermal polymerization initiator is used as the polymerization initiator, but when the curable material can be cured by active energy rays, a photopolymerization initiator may be included. Moreover, you may use combining a thermal-polymerization initiator and a photoinitiator. In addition, a polymerization initiator may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Furthermore, the curable material may contain arbitrary additives, such as a polymerization inhibitor, antioxidant, a ultraviolet absorber, an antistatic agent, a light stabilizer, an antifoamer, a leveling agent, for example. In addition, an additive may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

[2-3. Application method)
In the step (A), a curable material is applied to the surface of the substrate to form an application layer. A coating method is not particularly limited, and a known coating method can be employed. Specific coating methods include, for example, a wire bar coating method, a dip method, a spray method, a spin coating method, a roll coating method, a gravure coating method, an air knife coating method, a curtain coating method, a slide coating method, and an extrusion coating method. Etc.

[3. Step (B)]
After forming the coating layer of the curable material on the surface of the substrate in the step (A), the coating layer is cured to obtain a hard coat layer (B). The step (B) includes a step (b1) in which the surface portion of the coating layer is heated to a temperature higher than that of the portion other than the surface portion of the coating layer and the base material. Further, the step (B) may include a step (b2) of heating a portion other than the surface portion of the coating layer at a temperature lower than the temperature for heating the surface portion of the coating layer in the step (b1).

[3-1. Step (b1)]
In the step (b1), the surface portion of the coating layer is heated to a temperature higher than the portion other than the surface portion of the coating layer and the substrate. Thereby, a coating layer hardens | cures and a hard-coat layer is obtained.

In the heating in the step (b1), the surface portion of the coating layer is heated to a high temperature, so that the curing proceeds greatly. For this reason, the surface portion of the hard coat layer corresponding to the surface portion of the coating layer has high hardness.
Further, since the surface portion of the coating layer shrinks by the amount of curing, a large shrinkage force is generated on the surface portion of the hard coat layer. However, in the step (b1), the portion other than the surface portion of the coating layer does not become as hot as the surface portion of the coating layer, so that a large shrinkage force does not occur.
In this way, it is possible to prevent the hard coat film from curling as much as the entire hard coat layer curls the hard coat film while increasing the hardness of the surface of the hard coat layer. It is possible to achieve both high surface hardness.

  In the step (b1), since the substrate does not become as hot as the surface portion of the coating layer, it usually does not cause deformation, orientation relaxation, composition change, deterioration, etc. due to heat. As described above, the surface of the hard coat layer can be hardened without giving a large heat to the substrate by selectively raising only the surface portion of the coating layer to a high temperature. Then, as the thermoplastic resin forming the base material, a resin that is susceptible to deformation, orientation relaxation, composition change, deterioration, etc. due to heat can be used. For this reason, since the range of selection of the material of a base material spreads, the freedom degree of design of a hard coat film can be raised.

  In addition, since the base material is not easily deformed in the step (b1) as described above, the long base material is bent due to heat in the production line and cannot be conveyed, or the base material is partially deformed to cause spots. Can be prevented.

  Further, as described above, in the step (b1), since the orientation relaxation, composition change and deterioration do not occur, the phase difference of the base material before heating is maintained, and the base material before heating is also heated before heating. The same phase difference as that of the substrate can be expressed. Therefore, since the retardation of the base material before the step (B) can be maintained, the retardation of the hard coat film can be easily controlled.

  The surface portion of the coating layer in step (b1), the portion other than the surface portion, and the temperature at which the substrate is heated are usually set according to the composition of the substrate and the hard coat layer and the target hardness. From the viewpoint of effectively utilizing the advantage that the coating layer can be cured without causing deformation or the like in the substrate, the maximum heating temperature Th1 of the coating layer in the step (b1) and the thermoplastic resin that forms the substrate The temperature is set so that the difference Th1−Ts from the Vicat softening temperature Ts is preferably greater than −20 ° C., more preferably greater than −10 ° C., and particularly preferably greater than 10 ° C. The maximum heating temperature Th1 of the coating layer usually means the highest temperature reached on the surface of the coating layer.

  In step (b1), the temperature of the surface opposite to the surface on which the coating layer of the substrate is formed is preferably Ts-20 ° C. or less, more preferably Ts-30 ° C. or less, and particularly preferably Ts—. It is 40 degrees C or less. In step (b1), the substrate cannot be heated with a large amount of heat, so the temperature of the surface opposite to the surface on which the coating layer of the substrate is formed becomes low. At this time, if the temperature of the surface opposite to the surface on which the coating layer is formed is sufficiently low as described above, the deformation, orientation relaxation, composition change and deterioration of the substrate can be stabilized. Can be prevented.

  From the viewpoint of effectively suppressing curling of the hard coat film, it is preferable to heat a small portion in the thickness direction of the coating layer in the step (b1). Specifically, the surface portion 13 that is selectively heated to a high temperature in the coating layer 12 is preferably a portion from the surface 15 of the coating layer 12 to 2/3 or less of the thickness T of the coating layer 12. A portion up to 1/2 or less of the thickness T of 12 is more preferable, and a portion up to 1/3 or less of the thickness T of the coating layer 12 is particularly preferable (see FIG. 1).

[3-2. Step (b2)]
The step (B) preferably includes a step (b2) of heating a portion other than the surface portion of the coating layer at a temperature lower than the temperature of heating the surface portion of the coating layer in the step (b1). Thereby, parts other than the surface part of an application layer can be hardened.

  In the step (b2), the temperature at which the portion other than the surface portion of the coating layer is heated is lower than the temperature at which the surface portion of the coating layer is heated. It becomes lower than the hardness of the surface portion. However, since the surface portion of the hard coat layer is sufficiently hardened by heating in the step (b1), the surface hardness of the hard coat film can be sufficiently increased. In addition, since a large shrinkage force is not generated in portions other than the surface portion of the hard coat layer, it is possible to prevent a large shrinkage force from being generated in the entire hard coat layer.

  The step (b2) may be performed before the step (b1), may be performed after the step (b1), or may be performed simultaneously with the step (b1). When the step (b2) is performed before or after the step (b1), the surface portion of the coating layer is usually heated to the same temperature as the portion other than the surface portion of the coating layer. Moreover, when performing a process (b2) simultaneously with a process (b1), the surface part of an application layer is heated by high temperature rather than parts other than the surface part of an application layer. Furthermore, in any case, the substrate is usually heated to the same temperature as the portion other than the surface portion of the coating layer. Therefore, the temperature at which the portion other than the surface portion of the coating layer is heated in the step (b2) is preferably set to a temperature that does not cause deformation, orientation relaxation, composition change, deterioration, etc. due to heat. Specifically, based on the Vicat softening temperature Ts of the thermoplastic resin forming the base material, it is a temperature at which the coating layer can be cured, and is preferably Ts-20 ° C or lower, more preferably Ts-30 ° C or lower. The heating is particularly preferably performed at a temperature of Ts-40 ° C. or lower.

[3-3. Heating device)
Examples of the heating device that selectively heats the surface portion of the coating layer to a high temperature as in the step (b1) include a flash lamp annealing device and an excimer laser annealing device, among which a flash lamp annealing device is used. preferable. The flash lamp annealing device is a device that irradiates light on a film and heats the film with the light. In the flash lamp annealing apparatus, the irradiation time of light can be shortened to a short time such as milliseconds or microseconds, so that a thin portion near the surface of the film can be selectively heated. In particular, the thickness of the portion to be heated can be easily controlled by adjusting the light irradiation time, the irradiation intensity, and the like, which is suitable as a heating device used in the step (b1). In addition, the frequency | count of light irradiation may be 1 time, and may be 2 times or more.

Hereinafter, an example of a flash lamp annealing apparatus will be described with reference to the drawings. FIG. 2 is a cross-sectional view schematically showing an example of the configuration of the flash lamp annealing apparatus.
As shown in FIG. 2, the flash lamp annealing device 20 includes a flash lamp unit 100 including a flash lamp 110 as a light source and a reflector 120. The flash lamp 110 is housed in a housing 140 that includes the reflective material 120 and the cover 130, and the light L emitted from the flash lamp 110 passes through the cover 130 directly or after being reflected by the reflective material 120. Thus, only the surface portion of the coating layer 220 is heated when it hits the coating layer 220 formed on the surface 210 of the substrate 200.

  Further, the flash lamp annealing device 20 may include a preheating unit 300 as necessary. Since the preheating unit 300 includes the heater 310, the substrate 200 and the coating layer 220 can be heated separately from the light heating by the flash lamp unit 100. There is no problem in heating the entire base material 200 and coating layer 220 as long as deformation and orientation relaxation do not occur. For example, the heating in the step (b2) may be performed by the heater 310.

  In the flash lamp annealing apparatus 20 shown in FIG. 2, the preheating unit 300 includes a heater 310 in a housing 340 including a base 320 and a cover 330, and a base material on which a coating layer 220 is formed on the heater 310. 200 has a passage 350 through which 200 passes. The surface of the coating layer 220 is continuously or intermittently irradiated by the light L transmitted through the cover 330 onto the coating layer 220 formed on the surface of the base material 200 conveyed through the passage 350. The part is heated. Further, the heating with the light L is not necessarily performed while the substrate 200 is being transported. For example, the substrate 200 may be placed on the passage 350 and heated.

  In the step (b1), in order to selectively heat the surface portion of the coating layer 220 to a high temperature, the wavelength of the light L is set to a wavelength that is easily absorbed by the curable material, or the irradiation time of the light L is shortened. It is preferable that the intensity of the light L is set appropriately, or the atmosphere in the passage 350 is set appropriately. The specific setting is usually set according to the type of the curable material, the thickness of the coating layer 220, and the like.

  An example of the flash lamp annealing device shown in FIG. 2 is given by product name. For example, a flash lamp annealing device manufactured by DTF (DTF pamphlet, [online], [search January 6, 2011], Internet < URL: http://www.thin-film.de/fileadmin/media/Website/Documente/Download_Center/Techniche_Informationen/No2_FLA.pdf>).

[3-4. Active energy ray irradiation process)
When using what can be hardened | cured with an active energy ray as a curable material, you may irradiate an active energy ray to an application layer, and may harden an application layer as needed. Thereby, since hardening of an application layer can be advanced rapidly, the manufacture efficiency of a hard-coat film can be improved.

  The irradiation time and irradiation intensity of the active energy ray are usually set according to the surface hardness of the target hard coat film. The irradiation with active energy rays may be performed before the step (b1) and the step (b2), or may be performed after the step (b1) and the step (b2), and the step (b1) and the step (b2). ) May be done at the same time. However, it is preferable to irradiate the active energy ray from the coating layer side of the substrate, rather than irradiating the active energy ray from the side opposite to the coating layer of the substrate through the substrate. Thereby, since many active energy rays can be irradiated to the surface part of a coating layer, the surface part of a coating layer can be hardened more than parts other than a surface part.

[3-5. Changes in coating layer and substrate in step (B)]
As described above, the hard coat layer is formed on the surface of the substrate by curing the coating layer in the step (B). At this time, the surface portion of the coating layer is greatly shrunk by heating in the step (b1), but portions other than the surface portion of the coating layer are not shrunk as much as the surface portion of the coating layer. Therefore, the volume shrinkage rate of the surface portion of the hard coat layer in the step (B) is larger than the volume shrinkage rate of the portion other than the surface portion of the hard coat layer.

  What is necessary is just to set the range of the specific volume shrinkage rate according to the surface hardness of the target hard coat film. For example, the volume shrinkage ratio of the surface of the hard coat layer in the step (B) is usually 10% or more, preferably 12% or more, more preferably 14% or more, usually 50% or less, preferably 30% or less, more preferably. Is 20% or less. If the volume shrinkage on the surface of the hard coat layer is in the above range, usually, curling of the hard coat film and high surface hardness can both be achieved.

The volume shrinkage rate is determined based on the volume of the coating layer portion when a portion of the coating layer before curing in step (B) is cured to become a part of the hard coat layer. It is a ratio representing how much the volume of the later hard coat layer portion is reduced. The volume shrinkage is obtained by the following formula.
Volume shrinkage (%) = 100 × (density after curing−density before curing) / density after curing

  Since the density increases as the shrinkage progresses, the degree of shrinkage can usually be evaluated by measuring the density of the surface portion of the hard coat layer. However, since the thickness of the coating layer and the hard coat layer is thin, it is difficult to directly measure the volume shrinkage rate. Therefore, in general, a sample made of the same material as the coating layer used for manufacturing the hard coat film is prepared separately from the hard coat film, and the sample is heated to the same temperature as the method for manufacturing the hard coat film. And cured for evaluation.

Further, as described above, in the step (B), the base material hardly undergoes changes such as deformation, orientation relaxation, composition change, and deterioration. Therefore, the base material can usually maintain the same optical characteristics as before performing the step (A). For example, the degree of increase in the haze of the base material after obtaining the hard coat layer in the step (B) compared to before performing the step (A) is usually 0.5% or less, preferably 0.3% or less, More preferably, it is 0.2% or less.
In addition, the said haze is measured based on JISK-7136, for example using a commercially available haze meter. The degree of increase in haze is the difference between the haze of the substrate after obtaining the hard coat layer and the haze of the substrate before performing the step (A).

[4. Other processes]
In the production method of the present invention, an optional step may be performed in addition to the above-described step (A) and step (B) as long as the effects of the present invention are not significantly impaired.
For example, you may perform the process of providing layers other than a base material and a hard-coat layer in a hard-coat film. As a specific example, a step of providing a low refractive index layer on the surface of the hard coat film may be performed, and the hard coat film may be provided with an antireflection function.
In addition, for example, a step of forming a hard coat layer on the surface of the substrate opposite to the surface on which the hard coat layer is formed may be performed in the same manner as in the steps (A) and (B). However, normally, in the hard coat film of the present invention, a hard coat layer is formed only on one surface of the substrate. Considering that the conventional hard coat film provided with a hard coat layer only on one side of the substrate was easily curled, it is better to form a hard coat layer only on one side of the hard coat film of the present invention, This is because the advantage of the present invention of curling can be remarkably exhibited.

[5. Hard coat film)
As mentioned above, according to the manufacturing method of this invention, a hard-coat film provided with a base material and the hard-coat layer formed in the surface of a base material is obtained.

  Since the curl of the hard coat film of the present invention is suppressed, the curl height is low. The specific curl height of the hard coat film of the present invention is usually 20 mm or less, preferably 10 mm or less, more preferably 5 mm or less. The curl height refers to a 10 cm × 10 cm hard coat film, and the cut film is placed on a flat surface so that the hard coat layer faces upward at a temperature of 20 ° C. and a humidity of 50%. In this case, it means the height at which the film curls after 60 minutes and the four corners rise from the flat surface.

  The hard coat film of the present invention has a high hardness on the surface of the hard coat layer. The specific hardness may be set according to the use of the hard coat film, but the hardness of the surface of the hard coat layer is usually H or higher, preferably 2H or higher, more preferably 3H or higher. In addition, the said hardness is the pencil hardness measured with a 500-g load according to JIS-5600-5-4.

  Since the hardness of the surface of the hard coat layer is high, the surface of the hard coat layer is excellent in scratch resistance. Specifically, when the surface of the hard coat layer is reciprocated 10 times in a state where a load of 0.025 MPa is applied to the steel wool # 0000, it is preferable that no scratch is visually confirmed.

  From the viewpoint of stably exhibiting the function as an optical member, the hard coat film preferably has a total light transmittance in terms of 1 mm thickness of 80% or more, and more preferably 90% or more. The light transmittance can be measured using a spectrophotometer (manufactured by JASCO Corporation, ultraviolet-visible near-infrared spectrophotometer “V-570”) in accordance with JIS K0115.

  The hard coat film has a haze in terms of 1 mm thickness of preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. By setting the haze to a low value, the sharpness of the display image of the display device incorporating the hard coat film of the present invention can be enhanced. Here, the haze is an average value obtained by measuring five points using a “turbidimeter NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K7361-1997.

  The content of the residual volatile component in the hard coat film is not particularly limited, but is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and further preferably 0.02% by weight or less. If the content of the residual volatile component exceeds 0.1% by weight, the optical characteristics such as the in-plane retardation Re and the thickness direction retardation Rth of the hard coat film may change over time. By setting the content of the volatile component within the above range, the dimensional stability can be improved, and the change over time of the optical properties of the hard coat film can be reduced. The volatile component is a substance having a molecular weight of 200 or less contained in the hard coat film, and examples thereof include a residual monomer and a solvent. The content of the volatile component can be quantified by analyzing the hard coat film by gas chromatography as a total of substances having a molecular weight of 200 or less.

  In addition, the hard coat layer may be a single layer composed of only one layer or a multilayer composed of two or more layers. However, from the viewpoint of reducing the thickness of the hard coat film, the hard coat layer is preferably a single layer.

  Since the surface portion of the hard coat layer is contracted more than the portion other than the surface portion, the density of the surface portion is usually larger than the density of the portion other than the surface portion. Especially, the density of the surface part on the opposite side to the board | substrate of a hard-coat layer is usually especially larger than the density of the interface part with the base material of a hard-coat layer. For this reason, when the hard coat layer is a single layer made of a material having the same composition, the density of the surface portion and the density of the portion other than the surface portion (particularly, the interface portion of the hard coat layer with the base material) By comparing, the difference in the degree of contraction between the surface portion and the portion other than the surface portion can be evaluated. Moreover, if the density of the surface part of a hard-coat layer and the density of parts other than the said surface part is adjusted, the shrinkage force which arises in a hard-coat layer can be controlled.

  Furthermore, since the surface portion of the hard coat layer is harder and harder than the portion other than the surface portion, the hardness of the surface portion is usually larger than the hardness of the portion other than the surface portion. Especially, the hardness of the surface part on the opposite side to the board | substrate of a hard-coat layer is usually especially larger than the hardness of the interface part with the base material of a hard-coat layer. For this reason, when the hard coat layer is a single layer formed of a resin having the same composition, the hardness of the surface portion and the hardness of the portion other than the surface portion (particularly, the interface portion of the hard coat layer with the base material) , The difference in the degree of shrinkage between the surface portion and the portion other than the surface portion can be evaluated. Further, the hardness of the surface portion and portions other than the surface portion may be evaluated by, for example, scratch resistance.

  The refractive index difference at the interface between the substrate and the hard coat layer is preferably 0.05 or less. When the refractive index difference is within the above range, it is possible to suppress light loss when light is transmitted through the hard coat film.

  The contact angle with respect to water on the surface of the hard coat layer is preferably 20 ° or more, preferably 60 ° or less, and more preferably 40 ° or less, even when the hard coat layer is not subjected to surface treatment. By setting the contact angle to be equal to or higher than the lower limit value of the above range, the hard coat film can be easily wound into a roll, and by setting the contact angle to be equal to or lower than the upper limit value, ITO and hard layers can be formed. Adhesion with the coat layer can be enhanced.

  The ten-point average height Rz of the hard coat layer is preferably 1.0 μm or less, and more preferably 0.5 μm or less. Thereby, the adhesiveness of a hard-coat layer and ITO can be improved.

  Although there is no restriction | limiting in the thickness of a hard-coat film, It is preferable that the thickness of a hard-coat layer is thin. In the production method of the present invention, one of the advantages is that the surface portion can be selectively heated to a high temperature even with a thin coating layer, so that this advantage can be used effectively. The specific thickness range of the hard coat layer is usually 30 μm or less, preferably 12 μm or less, more preferably 5 μm or less. Moreover, the minimum of the thickness of a hard-coat layer is 0.5 micrometer or more normally.

  The hard coat film may have a TD direction (traverse direction) dimension of, for example, 1000 mm to 2000 mm. Further, the hard coat film is not limited in the dimension in the MD direction, but is preferably a long film. Here, the “long” film means a film having a length of at least 5 times the width of the film, preferably a length of 10 times or more, specifically a roll. It has a length enough to be wound up into a shape and stored or transported. In addition, MD direction is the flow direction of the film in a production line, and usually corresponds to the longitudinal direction and the longitudinal direction of the film. The TD direction is a direction parallel to the film surface and perpendicular to the MD direction, and usually coincides with the width direction and the lateral direction of the film.

  In addition, the hard coat film of the present invention may include a low refractive index layer in order to improve the light transmittance in the visible light region. The low refractive index layer is a layer having a lower refractive index than the hard coat layer. Usually, the low refractive index layer is formed directly on the surface of the hard coat layer or indirectly through another layer. Examples of such a low refractive index layer include a porous material in which particles are included in a matrix. Examples of this porous material include the porous materials described in JP-A Nos. 2001-233611 and 2003-149642.

  The material used as the matrix is a material that meets the conditions such as the dispersibility of the particles and the transparency and strength of the low refractive index layer. For example, hydrolyzable organosilicon compounds such as polyester resin, acrylic resin, urethane resin, vinyl chloride resin, epoxy resin, melamine resin, fluorine resin, silicone resin, butyral resin, phenol resin, vinyl acetate resin, alkoxylane, Examples include decomposed products. Among these, acrylic resins, epoxy resins, urethane resins, silicone resins, hydrolyzable organosilicon compounds and hydrolysates thereof are preferred from the viewpoint of particle dispersibility and the strength of the porous material. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

Moreover, as particles contained in the porous material, for example, hollow fine particles are preferable. The hollow fine particles are preferably inorganic hollow fine particles. Examples of inorganic compounds that form the inorganic hollow fine particles include SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , Examples thereof include MoO ₃ , ZnO ₂ , WO ₃ , TiO ₂ —Al ₂ O ₃ , TiO ₂ —ZrO ₂ , In ₂ O ₃ —SnO ₂ , and Sb ₂ O ₃ —SnO ₂ . In addition, the example which connected the compound name with hyphen "-" represents that it is complex oxide. Among these, silica-based hollow fine particles are particularly preferable. In addition, gas may exist in the inside of hollow microparticles, and the liquid may exist. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  The number average particle diameter of the hollow fine particles is preferably 5 nm or more, more preferably 20 nm or more, more preferably 2000 nm or less, and even more preferably 100 nm or less. Thereby, the transparency of the low refractive index layer can be maintained. The number average particle diameter of the hollow fine particles can be measured by observation with a transmission electron microscope.

  Hollow fine particles can be produced, for example, by the method described in JP-A-2001-233611. Commercially available hollow fine particles may also be used. In addition, for the purpose of stabilizing the dispersion of the hollow microparticles or improving the affinity and binding properties with the matrix material, physical surface treatments such as plasma discharge treatment and corona treatment; surfactants, couplings Chemical surface treatment with an agent or the like may be performed. Furthermore, a hydrophilic group such as a hydroxyl group or an acryloyl group may be introduced on the surface of the hollow fine particles by chemical surface treatment.

  The hard coat film of the present invention may have a conductive layer. Usually, the conductive layer is formed directly on the surface of the hard coat layer or indirectly through another layer. The conductive layer is a transparent and conductive layer, and for example, a conductive layer used for a liquid crystal substrate or a touch panel may be used.

  The conductive layer is usually formed of a conductive material. Examples of the conductive material include conductive polymers; conductive pastes such as silver paste and polymer paste; metal colloids such as gold and copper; metal oxides such as ITO. Some examples of these include indium oxide doped with tin (ITO), tin oxide doped with antimony or fluorine (ATO or FTO), zinc oxide doped with aluminum (AZO), cadmium And oxides, oxides of cadmium and tin, metal oxides such as titanium oxide, zinc oxide and copper iodide; metals such as gold, silver, platinum and palladium; Among these, when used as a touch panel for a liquid crystal display device, ITO is particularly preferable in terms of light transmittance and durability. In addition, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.

  When the conductive layer is indirectly formed on the surface of the hard coat layer via another layer, it is preferable to form an intermediate layer made of a silicon compound between the hard coat layer and the conductive layer. By forming the intermediate layer made of a silicon compound, the adhesion between the conductive layer made of ITO or the like and the hard coat layer can be improved.

The surface resistivity of the conductive layer is preferably 100Ω / □ or more and 1000Ω / □ or less.
For example, when the conductive layer is formed of ITO, the thickness of the conductive layer is usually 10 nm or more, preferably 15 nm or more, and usually 150 nm or less, more preferably 70 nm or less.

  The conductive layer may be manufactured, for example, by sputtering, vacuum deposition, CVD, ion plating, sol-gel, or coating.

[6. (Use)
The hard coat film of the present invention can be used, for example, as a constituent member of a liquid crystal display device, and is particularly suitable for use in a liquid crystal display device having a touch panel function. Moreover, you may use a hard coat film provided with a light guide layer as an upper electrode or a lower electrode of a resistive film type touch panel, for example.

  Furthermore, you may use the hard coat film of this invention as a protective film of a polarizing plate, for example. In this case, a polarizing plate can be produced by bonding the hard coat film of the present invention to a polarizing film that is a polarizer. For bonding, an adhesive may be used as necessary. Further, the hard coat film may be bonded to only one surface of the polarizing film, or may be bonded to both surfaces. When a hard coat film is bonded to only one surface of the polarizing film, another highly transparent film may be bonded to the other surface of the polarizing film.

  The polarizing film may be produced, for example, by adsorbing iodine or a dichroic dye to a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath. Alternatively, for example, iodine or a dichroic dye may be adsorbed and stretched on a polyvinyl alcohol film, and a part of the polyvinyl alcohol unit in the molecular chain may be modified to a polyvinylene unit. Furthermore, as a polarizing film, you may use the polarizing film which has a function which isolate | separates polarized light into reflected light and transmitted light, such as a grid polarizing film, a multilayer polarizing film, a cholesteric liquid crystal polarizing film, for example. Among these, a polarizing film containing polyvinyl alcohol is preferable. The polarization degree of the polarizing film is preferably 98% or more, more preferably 99% or more. The thickness (average thickness) of the polarizing film is preferably 5 μm to 80 μm.

  The adhesive for bonding the polarizing film and the hard coat film is not particularly limited as long as it is optically transparent. For example, an aqueous adhesive, a solvent-type adhesive, a two-component curable adhesive, and an ultraviolet curable adhesive. Examples thereof include an adhesive and a pressure-sensitive adhesive. Among these, a water-based adhesive is preferable, and a polyvinyl alcohol-based water-based adhesive is particularly preferable. In addition, an adhesive agent may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The average thickness of the layer formed by the adhesive (adhesive layer) is preferably 0.05 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, more preferably 1 μm or less.

  There is no limitation on the method of laminating the hard coat film and the polarizing film.For example, after applying an adhesive on one surface of the polarizing film as necessary, the polarizing film and the hard coat film are bonded using a roll laminator. A method of bonding and drying as necessary is preferable. The drying time and drying temperature are appropriately selected according to the type of adhesive.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and may be arbitrarily changed without departing from the gist of the present invention and its equivalent scope. May be implemented. In the following description, “parts” and “%” representing amounts are based on weight unless otherwise specified. Further, in the following description, the operation was performed in an environment of normal temperature and pressure unless otherwise specified regarding temperature and pressure.

[Evaluation method]
1. Evaluation of Vicat softening temperature It measured using the heat distortion tester (made by Toyo Seiki) according to JISK7206.

2. Evaluation of pencil hardness Measured with a load of 500 g according to JIS-5600-5-4. Specifically, a pencil was placed on the hard coat layer at an angle of 45 °, and a load of 500 g was applied from the top of the pencil and scratched about 5 mm to confirm the degree of damage.

3. Evaluation of Volume Shrinkage Aside from the hard coat film, a sample formed of the same material as the coating layer used for the production of the hard coat film was prepared. The sample was cured by heating to the same temperature as in the method for producing a hard coat film, the density was measured using a hydrometer (manufactured by Micrometrics), and the volume shrinkage was calculated from the following equation.
Volume shrinkage (%) = 100 × (density after curing−density before curing) / density after curing

4). Evaluation of curling property A hard coat film was cut into a size of 10 cm × 10 cm. The cut out film was placed on a flat surface with the hard coat layer facing upward at a temperature of 20 ° C. and a humidity of 50%, and the curl property of the film after 60 minutes was evaluated according to the following criteria. Here, in the following criteria, “curl height” refers to the height at which the four corners of a curl are lifted from a flat surface when the film is curled.
A: Good curl is not recognized at all.
B: A slight curl is recognized, but the curl height is 20 mm or less.
C: Curl is clearly recognized and the curl height exceeds 30 mm.

5. Evaluation of scratch resistance In a state where a load of 0.025 MPa was applied to steel wool # 0000, the surface of the hard coat layer of the hard coat film was reciprocated 10 times, and the surface state after the reciprocation was visually observed. It was evaluated with.
In each example and comparative example, a sample provided with a hard coat layer was prepared in the same manner except that the corona treatment was not performed before application of the hard coat solution. The surface of the hard coat layer of the sample was attached on a glass plate coated with an adhesive, and then the substrate was removed by peeling or polishing to expose the interface portion of the hard coat layer with the substrate. The surface was subjected to a scratch resistance test in the same manner as described above, and evaluated according to the following criteria.
A: No scratch is observed.
B: There are 3 or more streak scratches.
C: There are 8 or more streak scratches.

[Production Example 1. Preparation of hard coat liquid A]
100 parts of urethane acrylate oligomer (“UV-1700B” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 18 parts of silica particles (manufactured by CIK Nanotech Co., Ltd., number average particle size 30 nm), and photopolymerization initiator (manufactured by Ciba Specialty Chemicals) 5 parts of “IRGACURE184”) was added and stirred using a stirrer to obtain a hard coat liquid A as a curable material.

[Example 1]
Using pellets of norbornene-based resin (“ZEONOR1060” manufactured by Nippon Zeon Co., Ltd., glass transition temperature 100 ° C., Vicat softening temperature 101 ° C.) dried at 100 ° C. for 5 hours, 40 μm thick unstretched as a substrate by extrusion molding Film A was obtained.
One side of the obtained unstretched film A was subjected to corona treatment, and then the hard coat liquid A was applied to form a coating layer having a thickness of 11 μm. The film having the unstretched film A and the coating layer thus obtained is referred to as an optical film A.
While heating the entire optical film A obtained at 80 ° C., at the same time, a surface portion from the surface of the coating layer of the optical film A to a thickness of 5 μm was heated at 120 ° C. with a heating device (a flash lamp annealing device manufactured by DTF). The coating layer was cured by heating and irradiation with ultraviolet rays to form a hard coat layer. Thereby, the hard coat film A provided with a base material and a hard coat layer was obtained. The evaluation results are shown in Table 1.
Separately, the volume shrinkage of the coating layer at 80 ° C., which is the entire heating temperature of the optical film A, and the volume shrinkage of the coating layer at 120 ° C., which is the heating temperature of the surface portion of the coating layer, are as described above. Measured with As a result, the volume shrinkage at 80 ° C. was 11%, and the volume shrinkage at 120 ° C. was 14%.

[Example 2]
An unstretched film B similar to the unstretched film A of Example 1 was produced, and this unstretched film B was obliquely stretched by an oblique stretcher so that the orientation angle was 45 °, and a retardation film B having a thickness of 30 μm. Got. The “orientation angle” means an angle formed by the slow axis with respect to the width direction of the unstretched film B.
One side of the obtained retardation film B was subjected to corona treatment, and then the hard coat liquid A was applied to form a 5 μm thick coating layer. The film having the retardation film B and the coating layer thus obtained is referred to as an optical film B.
The entire optical film B obtained was heated at 80 ° C., and at the same time, the surface portion from the surface of the coating layer of the optical film B to a thickness of 2 μm was heated at 120 ° C. with a heating device (a flash lamp annealing device manufactured by DTF). The coating layer was cured by heating and irradiation with ultraviolet rays to form a hard coat layer. Thereby, the hard-coat film B provided with a base material and a hard-coat layer was obtained. The evaluation results are shown in Table 1.

[Example 3]
A hard coat film C was prepared in the same manner as in Example 1 except that an acrylic resin (“SUMIPEX HT55Z” manufactured by Sumitomo Chemical Co., Ltd., glass transition temperature 95 ° C., Vicat softening temperature 104 ° C.) was used instead of the norbornene-based resin. Obtained. The evaluation results are shown in Table 1.

[Example 4]
A hard coat film C was prepared in the same manner as in Example 2 except that polycarbonate resin ("Wonderlite PC110" manufactured by Asahi Kasei Co., Ltd., glass transition temperature 148 ° C, Vicat softening temperature 130 ° C) was used in place of the norbornene resin. Obtained. The evaluation results are shown in Table 1.

[Comparative Example 1]
A hard coat film a was obtained in the same manner as in Example 2 except that heating by a heating device (manufactured by DTF, flash lamp annealing device) was not performed. The evaluation results are shown in Table 1.

[Comparative Example 2]
Hard coat in the same manner as in Example 2 except that heating was not performed by a heating device (a flash lamp annealing device manufactured by DTF) and the heating temperature of the entire optical film was changed from 80 ° C. to 120 ° C. Film b was obtained. The evaluation results are shown in Table 1.

[Consideration]
As can be seen from Table 1, in Examples 1 to 4, a hard coat film having a high surface hardness and a small curl property could be produced. Thus, it was confirmed that the present invention makes it possible to increase both the hardness of the hard coat layer and suppress curling of the hard coat film. In Examples 1 and 2, since the surface of the hard coat layer has higher scratch resistance than the hard coat layer at the interface with the substrate, the hardness of the hard coat layer surface is high. It was confirmed that the hardness of the interface of the hard coat layer with the substrate was larger.
On the other hand, the hard coat film a of Comparative Example 1 has low curl properties but low surface hardness. This is presumably because the surface hardness of the hard coat layer is low because the hard coat layer is not sufficiently cured.
Further, the hard coat film b of Comparative Example 2 has a high surface hardness but a large curling property. This is presumably because a large shrinkage force is generated in the hard coat layer as the entire hard coat layer is cured, and the hard coat film b is curled by the shrinkage force.

DESCRIPTION OF SYMBOLS 10 Base material 11 Surface of base material 12 Application layer 13 Surface part of application layer 14 Part other than surface part of application layer 15 Surface of application layer 20 Flash lamp annealing apparatus 100 Flash lamp unit 110 Flash lamp 120 Reflective material 130 Cover 140 Case Body 200 Base material 210 Base material surface 220 Application layer 300 Preheating unit 310 Heater 320 Base 330 Cover 340 Housing 350 Passage

Claims (13)

A base material, and a single-layer hard coat layer formed of a resin on the surface of the base material,
A hard coat film, wherein a hardness of a surface portion of the hard coat layer opposite to the substrate is larger than a hardness of an interface portion of the hard coat layer with the base material.   The hard coat film according to claim 1, wherein the surface of the hard coat layer has a hardness of H or more.   The hard coat film according to claim 1 or 2, wherein the curl height of the hard coat film is 20 mm or less.   The hard coat film according to claim 1, wherein the hard coat layer has a thickness of 30 μm or less.   The hard coat film as described in any one of Claims 1-4 whose hardness of a base material is B or less.   The hard coat film according to claim 1, wherein the substrate has a retardation.   The hard coat film according to claim 6, wherein the substrate is a stretched film.   The hard coat film according to claim 6 or 7, wherein the base material is obliquely stretched.   The hard coat film according to claim 1, wherein the substrate is a thermoplastic resin film, and the thickness of the substrate is 10 μm or more and 250 μm or less.   The hard coat film according to any one of claims 1 to 9, wherein the substrate is a multilayer film having two or more layers.   The hard coat film according to claim 1, wherein the hard coat layer contains fine particles.   A liquid crystal display device having a touch panel function, comprising the hard coat film according to claim 1.   The polarizing plate with which the hard-coat film as described in any one of Claims 1-11 and the polarizer were bonded together.

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