WO2013161582A1

WO2013161582A1 - Hard coating film and touch panel display device provided with same

Info

Publication number: WO2013161582A1
Application number: PCT/JP2013/060983
Authority: WO
Inventors: 亮太久木
Original assignee: コニカミノルタ株式会社
Priority date: 2012-04-27
Filing date: 2013-04-11
Publication date: 2013-10-31
Also published as: JP5943070B2; CN104246541B; CN104246541A; KR101627958B1; JPWO2013161582A1; KR20140146140A

Abstract

The hard coating layer (42) of a hard coating film (40) is formed on a cellulose ester film (41) by coating a hard coating layer-forming composition and curing said composition. The film thickness of the hard coating film (40) is 15 µm to 35 µm. 6 weight% to 12 weight% of a plasticizer that promotes the formation of a mixed layer (43) of the cellulose ester film (41) and the hard coating layer (42) is contained in the cellulose ester film (41), and more of the plasticizer is contained in the hard coating layer (42) side of the cellulose ester film (41) than the side opposite to the hard coating layer (42).

Description

Hard coat film and touch panel display device including the same

The present invention relates to a hard coat film in which a hard coat layer is formed on a cellulose ester film, and a touch panel display device including the hard coat film.

The modern society is said to be an advanced information society, and the volume of information distribution is increasing, and the demand for information collection and selection by individuals is increasing. In such a social background, needs for mobile information terminals that can process information while moving, such as portable information terminals and car navigation systems, are increasing, and development is being actively promoted.

2. Description of the Related Art In mobile information terminals, it has become a mainstream to use a transparent touch panel overlaid on a display unit of a display device with an emphasis on portability rather than using a keyboard as an interface with an operator.

In general displays equipped with a touch panel, it is required to give hardness to the image display surface of the display so as not to be damaged during handling. In response to this requirement, an optical film provided with a hard coat (HC) layer on a base film is generally bonded to an image display surface of a display to give hardness to the image display surface (for example, patents). Reference 1).

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a touch panel display device 100 including a general touch panel 200. The touch panel display device 100 is configured by bonding a touch panel 200 to the surface of the display device 300. The display device 300 is a liquid crystal display device, for example. In the figure, in order to clearly distinguish the touch panel 200 and the display device 300 from each other, they are illustrated apart from each other, but actually, they are used in a state where they are bonded together.

In the touch panel 200, transparent

conductive films

203 and 204 made of tin-doped indium oxide (ITO) are formed on the surfaces of the two light

transmissive substrates

201 and 202 so that the transparent

conductive films

203 and 204 face each other. The light-transmitting

base materials

201 and 202 are arranged to face each other with a spacer 205 interposed therebetween. A hard coat layer 206 for imparting hardness and scratch resistance is provided on the surface of the touch panel 200 opposite to the display device 300, that is, the surface on the input operation side of the light transmissive substrate 201. In this case, the light transmissive substrate 201 and the hard coat layer 206 can be combined and considered as one optical film (hard coat film).

With the finger or the stylus pen, information input operation is performed by pressing the hard coat layer 206, the light transmissive substrate 201 and the transparent conductive film 203 located on the input operation side with respect to the spacer 205 of the touch panel 200. By bringing the transparent conductive film 203 on the operation side into contact with the transparent conductive film 204 on the display device 300 side, position information of the pressed portion can be detected.

Moreover, in the touch panel 200, the structure which provides a hard-coat layer on the surface of the light transmissive base material 202 by the side of the display apparatus 300 other than the outermost surface of the light transmissive base material 201 by the side of input operation is also proposed (for example, Patent Document 2). In this case, the light transmissive substrate 202 and the hard coat layer can be considered as one optical film (hard coat film). In this configuration, it is considered that the surface of the light transmissive substrate 202 can be prevented from being damaged during handling of the light transmissive substrate 202 until bonding to the light transmissive substrate 201 on the input operation side.

By the way, the information portable terminal device is required not only to have high functionality but also to be further reduced in weight and thickness, and the touch panel and the display device are also required to be thin. Along with this, when the hard coat film is thinned, the hard coat film is easily cracked by an impact during operation of the touch panel.

In particular, in a display device equipped with a touch panel, when a hard coat film is provided on a portion other than the input operation side of the touch panel, the hard coat film requires a minimum hardness to prevent scratches on the surface, After the touch panel is bonded to the display device, it is important that the touch panel is not easily broken by an impact when the touch panel is operated. That is, the hard coat film is required to have both hardness for preventing damage and suppleness for preventing cracking even when the film thickness is thin.

JP 2008-165040 A (see paragraphs [0001], [0002], [0158], etc.) Japanese Patent Laying-Open No. 2011-133881 (see paragraph [0069], FIG. 8, etc.)

In view of the circumstances described above, an object of the present invention is to provide a hard coat film capable of reducing cracks due to impact with flexibility while ensuring hardness for preventing damage even when the film thickness is thin, and its hard It is providing the touch panel display device provided with the coat film.

The above object of the present invention is achieved by the following configuration.

1. A hard coat film in which a hard coat layer is formed by applying a composition for forming a hard coat layer on a cellulose ester film and curing the composition,
The film thickness of the hard coat film is 15 μm or more and 35 μm or less,
The plasticizer for promoting the formation of the mixed layer of the cellulose ester film and the hard coat layer is contained in the cellulose ester film in an amount of 6 wt% to 12 wt%, and the hard coat in the cellulose ester film The hard coat film is more contained on the hard coat layer side than on the side opposite to the layer.

2. 2. The hard coat film as described in 1 above, wherein the hard coat layer forming composition contains a ketone or acetate solvent.

3. 3. The hard coat film as described in 1 or 2 above, wherein the plasticizer is a phosphoric acid plasticizer.

4. In the cellulose ester film, the content of the plasticizer in the film thickness portion from the surface opposite to the side on which the hard coat layer is formed to a depth of 5 μm is the average content of the plasticizer in the entire cellulose ester film. On the other hand, the hard coat film as described in any one of 1 to 3 above, which is 10% or more and 50% or less. *

5. 5. The hard coat film as described in any one of 1 to 4 above, wherein the thickness of the mixed layer is 0.5% or more and 20% or less in a ratio to the thickness of the hard coat film.

6). When the plasticizer is the first plasticizer,
In addition to the first plasticizer, a second plasticizer for promoting the formation of a mixed layer of the cellulose ester film and the hard coat layer is contained in the cellulose ester film,
In the cellulose ester film, the content of the second plasticizer in the film thickness portion from the surface opposite to the side on which the hard coat layer is formed to a depth of 5 μm is the average of the plasticizer in the entire cellulose ester film. The hard coat film as described in any one of 1 to 5 above, which is 80% or more and 120% or less with respect to the content.

7). A display device for displaying an image;
A hard coat film bonded to the substrate surface on the image display side of the display device;
A touch panel display device having a touch panel member joined to the display device via the hard coat film,
The said hard coat film is comprised with the hard coat film in any one of said 1-6, The touchscreen display apparatus characterized by the above-mentioned.

According to said structure, the plasticizer which promotes formation of the mixed layer between a cellulose-ester film and a hard-coat layer is contained in the cellulose ester film in predetermined amount, and also contains a lot in the hard-coat layer side Therefore, the thickness of the formed mixed layer can be increased and the mixed layer can have an impact absorbing function. In addition, the plasticizer can give flexibility to the entire hard coat film. Thereby, even when the film thickness of the hard coat film is as thin as 15 μm or more and 35 μm or less, the hard coat film is cracked due to impact while ensuring the minimum hardness for preventing scratches. Can be reduced.

1 is a cross-sectional view illustrating a schematic configuration of a touch panel display device according to an embodiment of the present invention. It is sectional drawing which expands and shows the hard coat film applied to the said touchscreen display apparatus. It is sectional drawing which shows the structure of the outline of the conventional touch panel display device.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.

<Hard coat film>
The hard coat film of this embodiment is an optical film in which a hard coat layer is formed on a cellulose ester film, and the film thickness is 15 μm or more and 35 μm or less.

(Hard coat layer)
The hard coat layer according to the present embodiment preferably contains an actinic radiation curable resin from the viewpoint of excellent mechanical film strength (abrasion resistance, pencil hardness). That is, it is a layer mainly composed of a resin that is cured through a crosslinking reaction by irradiation with active rays (also called active energy rays) such as ultraviolet rays and electron beams. As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and an actinic radiation curable resin layer is formed by curing by irradiation with actinic radiation such as ultraviolet rays or electron beams. The Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin curable by ultraviolet irradiation is particularly excellent in mechanical film strength (abrasion resistance, pencil hardness). It is preferable from the point. Examples of the ultraviolet curable resin include an ultraviolet curable acrylate resin, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, and an ultraviolet ray. A curable epoxy resin or the like is preferably used, and an ultraviolet curable acrylate resin is particularly preferable.

As the ultraviolet curable acrylate resin, polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule. Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tri / tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, glycerol triacrylate relay , Dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol di Methacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pen Pentaerythritol tetramethacrylate, glycerol trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, etc. isocyanurate derivatives of the active energy ray-curable are preferably exemplified.

It is preferable that the hard coat layer according to the present embodiment contains an active energy ray-curable isocyanurate derivative because the effect of suppressing slippage between films is enhanced. The active energy ray-curable isocyanurate derivative is not particularly limited as long as it is a compound having a structure in which one or more ethylenically unsaturated groups are bonded to an isocyanuric acid skeleton. Compounds having three or more ethylenically unsaturated groups and one or more isocyanurate rings in the same molecule shown are preferred. The kind of ethylenically unsaturated group is an acryloyl group, a methacryloyl group, a styryl group, and a vinyl ether group, more preferably a methacryloyl group or an acryloyl group, and particularly preferably an acryloyl group.

In the formula, L ² is a divalent linking group, preferably a substituted or unsubstituted alkyleneoxy group or polyalkyleneoxy group having 4 or less carbon atoms in which a carbon atom is bonded to the isocyanurate ring, Particularly preferred are alkyleneoxy groups, which may be the same or different. R ² represents a hydrogen atom or a methyl group, and may be the same or different. Although the specific compound shown by General formula (1) is shown below, it is not restricted to these.

Other compounds include isocyanuric acid diacrylate compounds, and isocyanuric acid ethoxy-modified diacrylate represented by the following general formula (2).

Other examples include ε-caprolactone-modified active energy ray-curable isocyanurate derivatives, specifically, compounds represented by the following general formula (3). *

_One of R ₁ to R _{3 in} the above chemical structural formula is attached with a functional group represented by a, b, or c below, and at least one of R ₁ to R ₃ is a functional group of b.

a: —H or — (CH ₂ ) n—OH (n = 1 to 10, preferably n = 2 to 6)
b: — (CH ₂ ) n—O— (COC ₅ H ₁₀ ) m-COCH═CH ₂ (n = 1 to 10, preferably n = 2 to 6, m = 2 to 8)
c: — (CH ₂ ) n—O—R (R is a (meth) acryloyl group, n = 1 to 10, preferably n = 2 to 6)

Specific compounds represented by the general formula (3) are shown below, but are not limited thereto.

Examples of commercially available isocyanuric acid triacrylate compounds include A-9300 manufactured by Shin-Nakamura Chemical Co., Ltd. Examples of commercially available isocyanuric acid diacrylate compounds include Aronix M-215 manufactured by Toagosei Co., Ltd. Examples of the mixture of the isocyanuric acid triacrylate compound and the isocyanuric acid diacrylate compound include Aronix M-315 and Aronix M-313 manufactured by Toagosei Co., Ltd. ε-Caprolactone-modified active energy ray-curable isocyanurate derivatives include ε-caprolactone-modified tris- (acryloxyethyl) isocyanurate, Shin-Nakamura Chemical Co., Ltd. A-9300-1CL, Toagosei Co., Ltd. Examples include, but are not limited to, Aronix M-327.

As these commercial products, Adekaoptomer N series, Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries, Ltd.) , Aronix M-6100, M-8030, M-8060, Aronix M-215, Aronix M-315, Aronix M-313, Aronix M-327 (manufactured by Toagosei Co., Ltd.), NK-ester A-TMM-3L NK-ester AD-TMP, NK-ester ATM-35E, NK ester A-DOG, NK ester A-IBD-2E, A-9300, A-9300-1CL (Shin Nakamura Chemical Co., Ltd.), PE- 3A (Kyoeisha Chemical) etc. are mentioned. You may mix the said active ray curable resin individually or in mixture of 2 or more types. The viscosity at 25 ° C. of the actinic radiation curable resin is preferably 20 mPa · s or more and 2000 mPa · s or less. By using such a low-viscosity resin, a protrusion shape described later can be easily obtained. Specifically, within the viscosity range of the resin, sufficient fluidity of the resin composition (composition comprising an active ray curable resin and an additive other than a solvent) can be easily obtained in the drying step, and a protrusion shape can be obtained. It is easy to be done.

Measurement of the viscosity of the actinic radiation curable resin can be performed using a B-type viscometer under the condition of 25 ° C. with the resin stirred and mixed with a disper. A monofunctional acrylate may also be used.

Monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl Examples thereof include acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and cyclohexyl acrylate. Such monofunctional acrylates can be obtained from Nippon Kasei Kogyo Co., Ltd., Shin-Nakamura Chemical Co., Ltd., Osaka Organic Chemical Co., Ltd., etc.

When a monofunctional acrylate is used, it is preferable that the polyfunctional acrylate and the monofunctional acrylate are contained in a mass ratio of polyfunctional acrylate: monofunctional acrylate = 80: 20 to 98: 2.

(Photopolymerization initiator)
The hard coat layer preferably contains a photopolymerization initiator to accelerate the curing of the actinic radiation curable resin. The amount of the photopolymerization initiator is preferably contained in a mass ratio of photopolymerization initiator: active ray curable resin = 20: 100 to 0.01: 100. Specific examples of the photopolymerization initiator include alkylphenone series, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto. It is not something.

Commercially available products may be used as such photopolymerization initiators, and preferred examples include Irgacure 184, Irgacure 907, Irgacure 651, etc., manufactured by BASF Japan.

(Conductive agent)
The hard coat layer may contain a conductive agent in order to impart antistatic properties. Preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound.

(Additive)
In the hard coat layer, a silicone surfactant, a fluorosurfactant, a difference in contact angle with water before and after alkali treatment (θ _Δ ) can be easily controlled within a predetermined range (eg, 5 to 55 °), An anionic surfactant and an additive such as a fluorine-siloxane graft compound, a fluorine-based compound, and an acrylic copolymer may be contained. Further, a compound having an HLB value of 3 to 18 may be contained. By adjusting the type and amount of these additives, water repellency can be controlled, and θ _Δ can be easily controlled within the above range. If _θΔ is within the above range, the hard coat layer exhibits hydrophilicity, and when wound into a roll, the slipping property between the hard coat films is suppressed, and an effect of preventing winding deviation is obtained.

Here, the difference (θ _Δ ) between the water contact angle before and after the alkali treatment is alkali-treated under the conditions shown below at least from the water contact angle (θ) of the hard coat layer before the alkali treatment of the hard coat film. This is a value obtained by subtracting the water contact angle (θa) of the hard coat layer after this to obtain the difference (θ _Δ ) in water contact angle before and after the alkali treatment. The alkali treatment condition is a condition in which the hard coat film is immersed in a 2.5 mol / L potassium hydroxide solution at a temperature of 50 ° C. for 120 seconds. As for the contact angle with water, the sample was allowed to stand for 24 hours in an atmosphere having a temperature of 23 ° C. and a relative humidity of 55%, and then contact angle meter (Kyowa Interface Science Co., Ltd.) in an atmosphere having a temperature of 23 ° C. and a relative humidity of 55%. Product, trade name DropMaster DM100), the contact angle of pure water 7 minutes after dropping 1 μl of pure water was measured 7 times, and the average value of 5 measured values excluding the maximum and minimum values of the measured values It was.

The above HLB value is Hydrophile-Lipophile-Balance, hydrophilic-lipophilic-balance, and is a value indicating the hydrophilicity or lipophilicity of a compound. The smaller the HLB value, the higher the lipophilicity, and the higher the value, the higher the hydrophilicity. The HLB value can be obtained by the following calculation formula.

HLB = 7 + 11.7Log (Mw / Mo)
In the formula, Mw represents the molecular weight of the hydrophilic group, Mo represents the molecular weight of the lipophilic group, and Mw + Mo = M (molecular weight of the compound). Alternatively, according to the Griffin method, HLB value = 20 × total formula weight of hydrophilic part / molecular weight (J. Soc. Cosmetic Chem., 5 (1954), 294) and the like. Specific examples of the compound having an HLB value of 3 to 18 are listed below, but the present invention is not limited thereto. Figures in parentheses indicate HLB values.

Made by Kao Corporation: Emulgen 102KG (6.3), Emulgen 103 (8.1), Emulgen 104P (9.6), Emulgen 105 (9.7), Emulgen 106 (10.5), Emulgen 108 (12. 1), Emulgen 109P (13.6), Emulgen 120 (15.3), Emulgen 123P (16.9), Emulgen 147 (16.3), Emulgen 210P (10.7), Emulgen 220 (14.2) , Emulgen 306P (9.4), Emulgen 320P (13.9), Emulgen 404 (8.8), Emulgen 408 (10.0), Emulgen 409PV (12.0), Emulgen 420 (13.6), Emulgen 430 (16.2), Emulgen 705 (10.5), Emulgen 707 (12.1), Emulgen 09 (13.3), Emulgen 1108 (13.5), Emulgen 1118S-70 (16.4), Emulgen 1135S-70 (17.9), Emulgen 2020G-HA (13.0), Emulgen 2025G (15. 7), Emulgen LS-106 (12.5), Emulgen LS-110 (13.4), Emulgen LS-114 (14.0), manufactured by Nissin Chemical Industry Co., Ltd .: Surfynol 104E (4), Surfynol 104H (4), Surfinol 104A (4), Surfinol 104BC (4), Surfinol 104DPM (4), Surfinol 104PA (4), Surfinol 104PG-50 (4), Surfinol 104S (4), Surfi Knoll 420 (4), Surfynol 440 (8), Surfynol 4 5 (13), Surfynol 485 (17), Surfynol SE (6), manufactured by Shin-Etsu Chemical Co., Ltd .: X-22-4272 (7), X-22-6266 (8), KF-351 (12) KF-352 (7), KF-353 (10), KF-354L (16), KF-355A (12), KF-615A (10), KF-945 (4), KF-618 (11), KF-6011 (12), KF-6015 (4), KF-6004 (5).

Examples of the silicone surfactant include polyether-modified silicone, and the KF series manufactured by Shin-Etsu Chemical Co., Ltd. can be used. Examples of the acrylic copolymer include commercially available compounds such as BYK-350 and BYK-352 manufactured by BYK Japan. Examples of the fluorosurfactant include MegaFuck RS series and MegaFuck F-444 MegaFuck F-556 manufactured by DIC Corporation. The fluorine-siloxane graft compound refers to a copolymer compound obtained by grafting polysiloxane and / or organopolysiloxane containing siloxane and / or organosiloxane alone to at least a fluorine-based resin. Such a fluorine-siloxane graft compound can be prepared by a method as described in Examples described later. Alternatively, examples of commercially available products include ZX-022H, ZX-007C, ZX-049, and ZX-047-D manufactured by Fuji Chemical Industry Co., Ltd. Moreover, as a fluorine-type compound, Daikin Industries Ltd. OPTOOL DSX, OPTOOL DAC, etc. can be mentioned. These components are preferably added in the range of 0.005 parts by mass or more and 5 parts by mass or less with respect to the solid component in the hard coat composition.

(UV absorber)
A hard-coat layer may further contain the ultraviolet absorber demonstrated by the cellulose-ester film mentioned later. When the hard coat film is composed of two or more layers, it is preferable that the hard coat layer in contact with the cellulose ester film contains the ultraviolet absorber as the film configuration when containing the ultraviolet absorber.

As the content of the UV absorber, it is preferable that the UV absorber: hard coat layer constituting resin = 0.01: 100 to 10: 100 in terms of mass ratio. When two or more layers are provided, the thickness of the hard coat layer in contact with the cellulose ester film is preferably in the range of 0.05 to 2 μm. Two or more layers may be formed as a simultaneous multilayer. The simultaneous multi-layering is to form a hard coat layer by applying two or more hard coat layers on a base material without going through a drying step. In order to laminate the second hard coat layer on the first hard coat layer without using a drying process, the layers are stacked one after another with an extrusion coater or simultaneously with a slot die having a plurality of slits. Can be done.

(solvent)
The hard coat layer is a composition for forming a hard coat layer by diluting the above-mentioned components forming the hard coat layer with a solvent that swells or partially dissolves the cellulose ester film, and is applied onto the cellulose ester film by the following method. It is preferable to provide by drying and curing.

As the solvent, ketones (methyl ethyl ketone, acetone, etc.) and / or acetate esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (ethanol, methanol), propylene glycol monomethyl ether, cyclohexanone, methyl isobutyl ketone, etc. are preferable. The coating amount of the hard coat layer is suitably in the range of 0.1 to 40 μm as wet film thickness, and preferably in the range of 0.5 to 30 μm. The dry film thickness is in the range of an average film thickness of 0.01 to 20 μm, preferably in the range of 0.5 to 10 μm. More preferably, it is in the range of 0.5 to 5 μm.

As a method for applying the hard coat layer, known methods such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, and an ink jet method can be used.

(Hard coat layer forming method)
After applying the composition for forming a hard coat layer, it may be dried and cured (irradiated with active rays (also referred to as UV curing treatment)), and may be further subjected to heat treatment after UV curing, if necessary. The heat treatment temperature after UV curing is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 120 ° C. or higher. By performing the heat treatment after UV curing at such a high temperature, a hard coat layer having excellent film strength can be obtained.

Drying is preferably carried out at a high temperature of 90 ° C. or more in the rate of drying section. More preferably, the temperature in the decreasing rate drying section is 90 ° C. or higher and 125 ° C. or lower. By increasing the temperature of the rate-decreasing drying section, convection occurs in the coating resin during the formation of the hard coat layer, and as a result, irregular surface roughness tends to occur on the hard coat layer surface, and the arithmetic described later It is easy to control the average roughness Ra.

In general, it is known that the drying process changes from a constant state to a gradually decreasing state when drying starts. The decreasing section is called the decreasing rate drying section. In the constant rate drying section, the amount of heat flowing in is all consumed for solvent evaporation on the coating film surface, and when the solvent on the coating film surface decreases, the evaporation surface moves from the surface to the inside and enters the decreasing rate drying section. Thereafter, the temperature of the coating film surface rises and approaches the hot air temperature, so that the temperature of the actinic radiation curable resin composition rises, the resin viscosity decreases, and the fluidity increases.

As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually in the range of 50 to 1000 mJ / cm ² , preferably in the range of 50 to 300 mJ / cm ² . In the UV curing treatment, oxygen removal (for example, replacement with an inert gas such as nitrogen purge) can be performed to prevent reaction inhibition by oxygen. The cured state of the surface can be controlled by adjusting the removal amount of the oxygen concentration. This makes it possible to control the presence state of the additive on the hard coat layer surface, and as a result, it is easy to control _θΔ within the above range. When irradiating actinic radiation, it is preferably performed while applying tension in the film transport direction, and more preferably while applying tension in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the conveying direction on the back roller, or tension may be applied in the width direction or biaxial direction by a tenter. Thereby, a film having further excellent flatness can be obtained.

(Surface shape)
The arithmetic average roughness Ra of the hard coat layer is preferably in the range of 2 to 100 nm, particularly preferably in the range of 5 to 80 nm because the slippage between the films is suppressed and the effect of preventing winding deviation is enhanced. . The arithmetic average roughness Ra can be measured according to JIS (Japanese Industrial Standards; B0601: 2001).

The height of the protrusion shape for obtaining the arithmetic average roughness Ra is preferably in the range of 2 nm to 4 μm. The width of the protrusion shape is in the range of 50 nm to 300 μm, preferably in the range of 50 nm to 100 μm.

The 10-point average roughness Rz of the hard coat layer is 10 times or less of the centerline average roughness Ra, and the average mountain-valley distance Sm is preferably 5 to 150 μm, more preferably 20 to 100 μm, and the height of the protrusion from the deepest part of the unevenness Is preferably 0.5 μm or less, a standard deviation of an average mountain-valley distance Sm based on the center line is 20 μm or less, and a surface with an inclination angle of 0 to 5 degrees is preferably 10% or more. Arithmetic average roughness Ra, Sm, and Rz described above are values measured with an optical interference surface roughness meter (manufactured by ZYGO, NewView) in accordance with JIS B0601: 2001.

(Haze)
The haze of the hard coat film is preferably in the range of 0.2 to 10% in view of visibility when used in an image display device. The haze can be measured according to JIS-K7105 and JIS K7136.

(hardness)
The hard coat film of this embodiment has a pencil hardness, which is an index of hardness, of HB or more, more preferably H or more. If it is more than HB, the surface is hardly scratched. The pencil hardness is determined by adjusting the humidity of the produced optical film at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more, and then using a test pencil specified by JIS S 6006 under a load of 500 g. Or it is the value which measured the functional layer according to the pencil hardness evaluation method which JISK5400 prescribes | regulates.

<Cellulose ester film>
Examples of the cellulose ester film (hereinafter also referred to as cellulose acetate film) include a triacetyl cellulose film, a cellulose acetate propionate film, a cellulose diacetate film, and a cellulose acetate butyrate film. The cellulose ester film may be used in combination with polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, polyethylene resins, polypropylene resins, norbornene resins, fluororesins, and cycloolefin polymers. Examples of the commercially available cellulose ester film include Konica Minoltak KC8UX, KC4UX, KC8UY, KC4UY, KC6UA, KC4UA, KC4UE and KC4UZ (manufactured by Konica Minolta Opto, Inc.). The refractive index of the cellulose ester film is preferably 1.45 to 1.55. The refractive index can be measured according to JIS K7142-2008.

(Cellulose ester resin)
The cellulose ester resin (hereinafter also referred to as 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. For example, cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, etc. Further, mixed fatty acid esters such as cellulose acetate butyrate can be used.

Among the above description, the lower fatty acid esters of cellulose that are particularly preferably used are cellulose diacetate, cellulose triacetate, and cellulose acetate propionate. These cellulose esters can be used alone or in combination.

Cellulose diacetate preferably has an average degree of acetylation (amount of bound acetic acid) of 51.0% to 56.0%. Commercially available products include L20, L30, L40, and L50 manufactured by Daicel Corporation, and Ca398-3, Ca398-6, Ca398-10, Ca398-30, and Ca394-60S manufactured by Eastman Chemical Japan Co., Ltd. .

The cellulose triacetate preferably has an average degree of acetylation (bound acetic acid amount) of 54.0 to 62.5%, and more preferably cellulose triacetate having an average degree of acetylation of 58.0 to 62.5%. is there.

As cellulose triacetate, cellulose triacetate A having a number average molecular weight (Mn) of 125,000 or more and less than 155000, a weight average molecular weight (Mw) of 265,000 or more and less than 310,000, and Mw / Mn of 1.9 to 2.1, acetyl group substitution degree Triacetate having a molecular weight of 2.75 to 2.90, a number average molecular weight (Mn) of 155,000 to less than 180,000, a weight average molecular weight (Mw) of 290000 to less than 360,000, and Mw / Mn of 1.8 to 2.0 It is preferable to contain B.

Cellulose acetate propionate has an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, the following formula (I ) And (II) are preferably satisfied at the same time.

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
Among them, it is preferable that 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9.

The degree of substitution of the acyl group can be measured according to ASTM-D817-96, one of the standards formulated and issued by ASTM (American Society for Testing and Materials).

The number average molecular weight (Mn) and weight average molecular weight (Mw) of the cellulose ester can be measured using high performance liquid chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G
(Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Co., Ltd.) Mw = 1000,000 to 500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

(Thermoplastic acrylic resin)
A cellulose ester film and a thermoplastic acrylic resin may be used in combination. When used in combination, the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is preferably thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50.

Acrylic resin includes methacrylic resin. The acrylic resin is not particularly limited but is preferably composed of 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith. Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, alkyl acrylates such as acrylic acid and methacrylic acid. Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, Examples thereof include maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, and the like. These may be used alone or in combination of two or more.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used. Further, the weight average molecular weight (Mw) is preferably 80,000 to 500,000, more preferably 110,000 to 500,000.

The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography. Commercially available acrylic resins include, for example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electrochemical Industry Co., Ltd.) )) And the like. Two or more acrylic resins can be used in combination.

(Fine particles)
In order to improve the handleability, the cellulose ester film of the present embodiment has, for example, acrylic particles, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, and hydrated calcium silicate. It is preferable to contain a matting agent such as inorganic fine particles such as aluminum silicate, magnesium silicate and calcium phosphate and a crosslinked polymer. The acrylic particles are not particularly limited, but are preferably multi-layered acrylic granular composites. Among these, silicon dioxide is preferable in that the haze of the cellulose ester film can be reduced. The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably in the range of 5 to 16 nm, and particularly preferably in the range of 5 to 12 nm.

The cellulose acetate film of the present embodiment preferably contains an ester compound or a sugar ester represented by the following general formula (X) from the dimensional stability under environmental changes. First, the ester compound represented by the general formula (X) will be described.

Formula (X) B- (GA) n-GB
Wherein B is a hydroxy group or carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol residue having 4 to 12 carbon atoms. A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)

In the general formula (X), the alkylene glycol component having 2 to 12 carbon atoms includes ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl 1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol, and the like. Or it is used as a mixture of two or more. In particular, alkylene glycols having 2 to 12 carbon atoms are particularly preferable because of excellent compatibility with cellulose acetate. Examples of the aryl glycol component having 6 to 12 carbon atoms include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol and the like, and these glycols can be used as one kind or a mixture of two or more kinds.

Examples of the oxyalkylene glycol component having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These glycols may be used alone or in combination of two or more. Can be used as a mixture. Examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, and the like. Used as a mixture of two or more. Examples of the arylene dicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like. Specific examples of the compound represented by formula (X) (compound X-1 to compound X-17) are shown below, but are not limited thereto.

Next, the sugar ester compound will be described. The sugar ester compound is an ester other than cellulose ester, and is a compound obtained by esterifying all or a part of OH groups of sugars such as the following monosaccharide, disaccharide, trisaccharide or oligosaccharide. Examples of the sugar include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, raffinose And kestose. In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included. Among these compounds, compounds having a furanose structure and / or a pyranose structure are particularly preferable. Among these, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are preferable, and sucrose is more preferable. As oligosaccharides, maltooligosaccharides, isomaltooligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylo-oligosaccharides can also be preferably used.

The monocarboxylic acid used for esterifying the sugar is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. The carboxylic acid to be used may be one kind or a mixture of two or more kinds. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, Examples include unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid. Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof. Examples of preferred aromatic monocarboxylic acids include benzoic acid, aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralin An aromatic monocarboxylic acid having two or more benzene rings such as carboxylic acid, or a derivative thereof can be mentioned, and more specifically, xylic acid, hemelic acid, mesitylene acid, planicylic acid, γ-isojurylic acid, Julylic acid, mesitic acid, α-isoduric acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic acid, salicylic acid, o-, m, p-anisic acid, creosote acid, o-, m, p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratrum acid o- veratric acid, gallic acid, asarone acid, mandelic acid, homoanisic acid, homovanillic acid, homoveratric acid, o- homoveratric acid, Futaron acid, can be mentioned p- coumaric acid, especially benzoic acid. Among the ester compounds esterified, an acetyl compound into which an acetyl group has been introduced by esterification is preferable. Although the specific example of the sugar ester compound which can be used for this embodiment below is shown, it is not limited to these.

The sugar ester compound is preferably a compound represented by the general formula (Y). Below, the compound shown by general formula (Y) is demonstrated.

_(Wherein, R 1 ~ _{R 8} is a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group having 2 to 22 carbon atoms, or a substituted or unsubstituted arylcarbonyl group having 2 to 22 carbon atoms, _{R 1} R ₈ may be the same or different.

The compounds represented by formula (Y) are shown below in more detail (compound Y-1 to compound Y-23), but are not limited thereto. In the table below, when the average degree of substitution is less than 8.0, any one of R ₁ to R ₈ represents a hydrogen atom.

The substitution degree distribution can be adjusted to the target substitution degree by adjusting the esterification reaction time or mixing compounds with different substitution degrees.

The ester compound or sugar ester compound represented by the general formula (X) is preferably contained in the cellulose acetate film in an amount of 1 to 30% by mass, more preferably 5 to 25% by mass. It is particularly preferable to contain it.

(Other additives)
[Plasticizer]
The cellulose acetate film of this embodiment contains a plasticizer. The plasticizer is not particularly limited, but is a polyvalent carboxylic ester plasticizer, glycolate plasticizer, phthalate ester plasticizer, phosphate ester plasticizer, and polyhydric alcohol ester plasticizer, acrylic. A plasticizer etc. are mentioned. In these, as a plasticizer which promotes formation of the mixed layer mentioned later, it is preferable to use a phthalate ester plasticizer or a phosphate ester plasticizer, and among these, it is preferable to use a phosphate ester plasticizer. .

The polyhydric alcohol ester plasticizer is a plasticizer composed of an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. A divalent to 20-valent aliphatic polyhydric alcohol ester is preferred. Specific examples of the polyhydric alcohol ester plasticizer are shown below, but are not limited thereto.

The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate (EPEG), propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl Phthalyl ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalate Butyl butyl glycolate, butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, Chill phthalyl ethyl glycolate, and the like.

Examples of the phthalate ester plasticizer include diethyl phthalate (DEP), dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

Examples of the phosphate ester plasticizer include triphenyl phosphate (TPP), tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, biphenyl diphenyl phosphate (BDP), and the like. It is done.

The polycarboxylic acid ester plasticizer is a compound composed of an ester of a divalent or higher, preferably a divalent to 20-valent polyvalent carboxylic acid and an alcohol. Specific examples include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, tartaric acid Examples include, but are not limited to, diacetyldibutyl, tributyl trimellitic acid, tetrabutyl pyromellitic acid, and the like.

The acrylic plasticizer is preferably an acrylic polymer, and the acrylic polymer is preferably a homopolymer or copolymer of acrylic acid or alkyl methacrylate. Examples of the acrylate monomer include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate ( n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic Acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid (2-methoxyethyl), acrylic acid 2-ethoxyethyl), etc., or the acrylic acid ester may include those obtained by changing the methacrylic acid ester. The acrylic polymer is a homopolymer or copolymer of the above-mentioned monomers, but the acrylic acid methyl ester monomer unit preferably has 30% by mass or more, and the methacrylic acid methyl ester monomer unit has 40% by mass or more. preferable. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

(UV absorber)
The cellulose acetate film of this embodiment may contain an ultraviolet absorber. Since the ultraviolet absorber absorbs ultraviolet rays of 400 nm or less, durability can be improved. In particular, the ultraviolet absorber preferably has a transmittance of 10% or less at a wavelength of 370 nm, more preferably 5% or less, and still more preferably 2% or less. Specific examples of the ultraviolet absorber are not particularly limited. For example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic powders. Examples include the body.

More specifically, for example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6 -(Linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, and the like can be used. Commercially available products may be used. For example, TINUVIN such as TINUVIN 109, TINUVIN 171, TINUVIN 234, TINUVIN 326, TINUVIN 327, and TINUVIN 328 manufactured by BASF Japan Ltd. can be preferably used.

Preferably used ultraviolet absorbers are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferably benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers.

In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as an ultraviolet absorber. As the UV absorber, a polymer UV absorber can be preferably used, and a polymer type UV absorber is particularly preferably used.

As the benzotriazole ultraviolet absorber, TINUVIN 109 (octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazole-2-) manufactured by BASF Japan Ltd., which is a commercial product, is available. Yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate), TINUVIN 928 (2 -(2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol) and the like can be used. As the triazine-based ultraviolet absorber, TINUVIN 400 (2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) —manufactured by BASF Japan Ltd.— Reaction product of 5-hydroxyphenyl and oxirane), TINUVIN 460 (2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1,3-5 Triazine), TINUVIN 405 (2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester Reaction products) and the like.

The ultraviolet absorber is added by dissolving the ultraviolet absorber in an alcohol, such as methanol, ethanol, butanol or the like, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, and then becomes a film substrate. It may be added to the resin solution (dope) or directly during the dope composition. For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose acetate to disperse and then added to the dope.

The amount of the ultraviolet absorber used is preferably 0.5 to 10% by mass, more preferably 0.6 to 4% by mass with respect to the cellulose acetate film.

(Antioxidant)
The cellulose acetate film of the present embodiment may further contain an antioxidant (deterioration inhibitor). The antioxidant has a role of delaying or preventing the cellulose acetate film from being decomposed by a residual solvent amount of halogen in the cellulose acetate film, phosphoric acid of a phosphoric acid plasticizer, or the like. As the antioxidant, hindered phenol compounds are preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl) are used. -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3 5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate Etc. The amount of these compounds added is preferably 1 ppm to 10000 ppm by weight and more preferably 10 to 1000 ppm with respect to the cellulose acetate film.

(Disadvantage)
The cellulose ester film preferably has a defect of 5 μm or more in diameter of 1 piece / 10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less. Here, defects are caused by voids in the film (foaming defects) generated due to rapid evaporation of the solvent in the drying process of solution casting, foreign substances in the film forming stock solution, and foreign substances mixed in the film forming process. This refers to foreign matter (foreign matter defect) in the film to be transferred, roller scratch transfer and scratches. The diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope according to the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in surface shape, such as transfer of a roller scratch or an abrasion, the size of the defect can be confirmed by observing the defect with reflected light of a differential interference microscope.

When the number of defects is more than 1/10 cm square, for example, when a tension is applied to the film during processing in a later process, the film may be broken with the defect as a starting point and productivity may be reduced. When the defect diameter is 5 μm or more, the defect can be visually confirmed by polarizing plate observation or the like, and a bright spot may be generated when the film is used as an optical member. Even when the defects cannot be visually confirmed, when the hard coat layer is formed, the coating film may not be formed uniformly, and the coating may be lost.

The base film preferably has a breaking elongation in at least one direction of 10% or more, more preferably 20% or more, as measured in accordance with JIS-K7127-1999. The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

(optical properties)
The cellulose ester film preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. The haze value is preferably 2% or less, more preferably 1.5% or less. The total light transmittance and haze value can be measured according to JIS K7361 and JIS K7136.

The in-plane retardation value Ro of the cellulose ester film is preferably in the range of 0 to 5 nm, and the retardation value Rth in the thickness direction is preferably in the range of −20 to 20 nm. Alternatively, an optical compensation film having an in-plane retardation value Ro of 20 to 70 nm and a thickness direction retardation value Rth of 70 to 400 nm may be used.

Ro and Rth are values defined by the following formulas (i) and (ii).

Formula (i) Ro = (nx−ny) × d
Formula (ii) Rth = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the cellulose ester film plane, ny is the refractive index in the direction perpendicular to the slow axis in the substrate film plane, and nz is the refractive index in the thickness direction of the cellulose ester film. The rate and d each represent the thickness (nm) of the cellulose ester film.)

The retardation can be obtained at a measurement wavelength of 590 nm in an environment of 23 ° C. and 55% RH (relative humidity) using, for example, KOBRA-21ADH (manufactured by Oji Scientific Instruments). By using the cellulose ester film controlled to the above retardation value, it is preferable from the viewpoint of excellent visibility when used in an image display device such as a touch panel or a liquid crystal display device. Retardation can be adjusted by the kind and addition amount of a plasticizer mentioned above, the film thickness of a cellulose ester film, stretching conditions, and the like.

(Film formation of cellulose ester film)
Next, although the example of the film forming method of a cellulose-ester film is demonstrated, it is not limited to this. As a method for producing a cellulose ester film, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, a hot press method, or the like can be used.

(Organic solvent)
The organic solvent useful for forming a resin solution (dope composition) when a cellulose ester film is produced by a solution casting method is limited as long as it dissolves a cellulose ester resin and other additives at the same time. Can be used without any problem. For example, as a chlorinated organic solvent, methylene chloride, as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, etc. Can, methylene chloride, methyl acetate, ethyl acetate, may be used preferably acetone. The solvent is preferably a dope composition in which a total of 15 to 45 mass% of cellulose ester resin and other additives are dissolved.

[Solution casting film forming method]
In the solution casting film forming method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-shaped or drum-shaped metal support, and drying the cast dope as a web It is performed by the process of carrying out, the process of peeling the web from the metal support, the process of stretching or maintaining the width of the peeled web, the process of further drying, and the process of winding up the finished cellulose ester film.

As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.

The cast width can be 1 ~ 4m. The surface temperature of the metal support in the casting step is set to −50 ° C. to below the temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

The support temperature is preferably determined appropriately from 0 to 100 ° C., more preferably from 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent. The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing warm air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short.

When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there is a case where wind at a temperature higher than the target temperature is used while preventing foaming. is there.

In particular, it is preferable to efficiently dry by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

In order for the cellulose ester film to obtain good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 60%. It is 130% by mass, particularly preferably 20 to 30% by mass or 70 to 120% by mass. The amount of residual solvent is defined by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

Further, in the drying step of the cellulose ester film, the web is peeled off from the metal support and dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably. Is 0 to 0.01% by mass or less.

In the film drying step, a roller drying method (a method in which webs are alternately passed through a plurality of rollers arranged above and below) and a tenter method (a method in which the web is dried while transporting the web) are employed.

In the stretching step, the film can be sequentially or simultaneously stretched in the longitudinal direction (MD direction) and the lateral direction (TD direction). The draw ratios in the biaxial directions perpendicular to each other are preferably in the range of 1.0 to 2.0 times in the MD direction and 1.05 to 2.0 times in the TD direction, respectively. It is preferably performed in the range of 1.0 to 1.5 times and 1.05 to 2.0 times in the TD direction. For example, a method of making a difference in peripheral speed between a plurality of rollers and stretching in the MD direction using the difference in peripheral speed of the roller between them, fixing both ends of the web with clips and pins, and widening the interval between the clips and pins in the traveling direction And a method of stretching in the MD direction, a method of stretching in the transverse direction and stretching in the TD direction, a method of stretching the MD direction and the TD direction at the same time, and stretching in both directions.

It is preferable to perform the width maintenance or the stretching in the width direction in the film forming process by a tenter. The tenter in this case may be a pin tenter or a clip tenter.

The film transport tension in the film forming process using a tenter or the like is preferably 120 to 200 N / m, more preferably 140 to 200 N / m, and most preferably 140 to 160 N / m, although it depends on the temperature.

The stretching temperature is (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C., more preferably (Tg-5), where Tg is the glass transition temperature of the cellulose ester film. ~ (Tg + 20) ° C.

The Tg of the cellulose ester film can be controlled by the material type constituting the film and the ratio of the constituting materials. The Tg when the cellulose ester film is dried is preferably 110 ° C. or higher, more preferably 120 ° C. or higher, and particularly preferably 150 ° C. or higher. The glass transition temperature is preferably 190 ° C. or lower, more preferably 170 ° C. or lower. The Tg of the cellulose ester film can be determined by the method described in JIS K7121. The stretching temperature is preferably 150 ° C. or more and the stretching ratio is 1.15 times or more because the surface is appropriately roughened. Roughening the surface of the cellulose ester film is preferable because it improves slipperiness and improves surface processability.

[Melt casting method]
The cellulose ester film may be formed by a melt casting film forming method. In the melt casting film forming method, a composition containing other additives such as a cellulose ester resin and a plasticizer is heated and melted to a temperature showing fluidity, and then a melt containing the fluid cellulose ester is cast. To do.

As the melt casting film forming method, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded in advance and pelletized.

Pelletization may be performed by a known method, for example, dry cellulose ester, plasticizer, and other additives are fed to an extruder with a feeder, kneaded using a monoaxial or biaxial extruder, and formed into a strand from a die. Can be extruded, water-cooled or air-cooled, and then cut.

Additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders. A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

The extruder is preferably processed at a temperature as low as possible so that it can be pelletized so that the shearing force is suppressed and the resin does not deteriorate (molecular weight reduction, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

Film formation is performed using the pellets obtained as described above. Of course, it is also possible to feed the raw material powder as it is to the extruder with a feeder and form a film as it is without pelletization.

When the above pellets are extruded using a single-screw or twin-screw type extruder, the melting temperature is set to about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign matter, and then formed into a film from a T die. The cellulose ester film is formed by casting, nipping the film between the cooling roller and the elastic touch roller, and solidifying the film on the cooling roller.

When introducing pellets from the supply hopper into the extruder, it is preferable to prevent oxidative decomposition and the like under vacuum, reduced pressure, or inert gas atmosphere.

It is preferable to stably adjust the extrusion flow rate of the pellets by introducing a gear pump. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances. The stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

Additives such as plasticizers and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add the additive uniformly, it is preferable to use a mixing device such as a static mixer.

When the cellulose ester film is nipped between the cooling roller and the elastic touch roller, the temperature of the cellulose ester film on the touch roller side is preferably Tg or more (Tg + 110 ° C.) or less of the film. A known roller can be used as the roller having an elastic surface used for such a purpose.

The elastic touch roller is also called a pinching rotator. A commercially available elastic touch roller can also be used.

When peeling the cellulose ester film from the cooling roller, it is preferable to control the tension to prevent deformation of the film.

Moreover, it is preferable that the cellulose ester film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roller. As a stretching method, a known roller stretching machine, a tenter or the like can be preferably used. The stretching temperature is usually preferably in the temperature range of Tg to (Tg + 60) ° C. of the resin constituting the film.

Before winding up the film, the edges may be slit and cut to the product width, and knurled (embossed) may be applied to both ends to prevent sticking and scratching during winding. The knurling can be performed by heating or pressurizing using a metal ring having an uneven pattern on the side surface. Since the cellulose ester film is deformed and cannot be used as a product, the clip holding portions at both ends of the film are usually cut out and reused.

(Physical properties of cellulose ester film)
As for the film thickness of the cellulose-ester film in this embodiment, it is desirable that they are 10 micrometers or more and 30 micrometers or less. The width of the cellulose ester film is preferably 1 to 4 m. If it exceeds 4 m, conveyance becomes difficult.

Further, the length of the cellulose ester film is preferably 500 to 10000 m, more preferably 1000 to 8000 m. By setting it as the range of the said length, it is excellent in the processability in application | coating, such as a hard-coat layer, and the handleability of a cellulose-ester film itself.

The arithmetic average roughness Ra of the cellulose ester film is preferably 2 to 10 nm, more preferably 2 to 5 nm. The arithmetic average roughness Ra can be measured according to JIS B0601: 1994.

Further, the contact angle with water before the alkali treatment of the cellulose ester film is generally in the range of 40 ° to 80 °, preferably 50 ° to 70 °. The contact angle with water after the alkali treatment is generally 10 ° to 60 °, preferably 20 ° to 60 °, depending on the alkali treatment conditions. The water contact angle is a value measured according to the method described in the method for measuring the water contact angle of the hard coat layer.

It is estimated that the water contact angle of the hard coat layer is lowered by the alkali treatment and approaches the water contact angle of the cellulose ester film, whereby the hydrophilic layers are laminated to each other, and an anti-winding effect is obtained. . As an alkali treatment method, the cellulose ester film is immersed in an alkali solution, washed with water and dried. Further, after the alkali treatment, neutralization in an acidic water step may be performed, followed by washing with water and drying.

Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the concentration of hydroxide ions is preferably in the range of 0.1 to 5 mol / L, preferably 0.5 mol / L to 3 mol / L. More preferably, it is in the range. Furthermore, the temperature of the alkaline solution is preferably in the range of 25 to 90 ° C, more preferably in the range of 40 to 70 ° C. The alkali treatment time is in the range of 5 seconds to 5 minutes, preferably in the range of 30 seconds to 3 minutes.

<Other layers>
When the hard coat film of this embodiment is provided on the surface of the touch panel member opposite to the display device, other layers such as an antireflection layer and a conductive layer are provided on the hard coat layer of the hard coat film. Can be provided.

<Antireflection layer>
The hard coat film of this embodiment can be used as an antireflection film having an external light antireflection function by coating an antireflection layer on the hard coat layer.

The antireflection layer is preferably formed in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is composed of a low refractive index layer having a refractive index lower than that of the protective film as a support, or a combination of a high refractive index layer and a low refractive index layer having a higher refractive index than that of the protective film as a support. It is preferable. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers, and three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used. As the layer structure, the following structure is conceivable, but is not limited thereto.

Cellulose ester film / hard coat layer / low refractive index layer Cellulose ester film / hard coat layer / high refractive index layer / low refractive index layer Cellulose ester film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index Layer hard coat layer / cellulose ester film / hard coat layer / low refractive index layer hard coat layer / cellulose ester film / hard coat layer / high refractive index layer / low refractive index layer hard coat layer / cellulose ester film / hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Low refractive index layer / Hard coat layer / Cellulose ester film / Hard coat layer / Low refractive index layer

(Low refractive index layer)
The low refractive index layer preferably contains silica-based fine particles, and the refractive index is preferably in the range of 1.30 to 1.45 when measured at 23 ° C. and wavelength of 550 nm.

The film thickness of the low refractive index layer is preferably in the range of 5 nm to 0.5 μm, more preferably in the range of 10 nm to 0.3 μm, and in the range of 30 nm to 0.2 μm. Most preferred.

The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and porous or hollow inside are preferably hollow silica-based fine particles.

The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.

General formula (OSi-1): Si (OR) ₄
In the formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used as the organosilicon compound represented by the general formula.

In addition, a solvent, and if necessary, a silane coupling agent, a curing agent, a surfactant and the like may be added to the composition for forming a low refractive index layer. The composition for forming a low refractive index layer is a thermosetting and / or photocuring mainly comprising a fluorine-containing compound containing a fluorine atom in a range of 35 to 80% by mass and containing a crosslinkable or polymerizable functional group. You may contain the compound which has property. Specifically, a fluorine-containing polymer or a fluorine-containing sol-gel compound is used. Examples of the fluorine-containing polymer include hydrolysates and dehydration condensates of perfluoroalkyl group-containing silane compounds [eg (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane], and fluorine-containing monomers. Examples thereof include fluorine-containing copolymers having units and cross-linking reactive units as constituent units.

(High refractive index layer)
The refractive index of the high refractive index layer is preferably adjusted to a range of 1.4 to 2.2 by measurement at 23 ° C. and a wavelength of 550 nm. The thickness of the high refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm.

The adjustment of the refractive index of the high refractive index layer can be realized by adding metal oxide fine particles and the like. The metal oxide fine particles to be used preferably have a refractive index of 1.80 to 2.60, more preferably 1.85 to 2.50. The kind of metal oxide fine particles is not particularly limited, and Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S A metal oxide having at least one element selected from can be used.

(Conductive layer)
The hard coat film may be configured by forming a conductive layer on the hard coat layer. As the conductive layer provided, a generally well-known conductive material can be used. For example, metal oxides such as indium oxide, tin oxide, indium tin oxide, gold, silver, and palladium can be used. These can be formed as a thin film on the hard coat film by vacuum deposition, sputtering, ion plating, solution coating, or the like. Moreover, it is also possible to form a conductive layer using the organic conductive material which is the above-described π-conjugated conductive polymer.

In particular, a conductive material that is excellent in transparency and conductivity, and that has a main component of any one of indium oxide, tin oxide, and indium tin oxide obtained at a relatively low cost can be suitably used. Although the thickness of the conductive layer varies depending on the material to be applied, it cannot be said unconditionally. However, the surface resistivity is 1000Ω or less, preferably 500Ω or less, and considering the economy, A range of 10 nm or more, preferably 20 nm or more and 80 nm or less, preferably 70 nm or less is suitable. In such a thin film, visible light interference fringes due to uneven thickness of the conductive layer are unlikely to occur.

<Touch panel display device>
Next, a touch panel display device having the hard coat film of the present embodiment will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of a touch panel display device 10 of the present embodiment. The touch panel display device 10 is configured by bonding the touch panel member 20 to the surface of the display device 30 via the hard coat film 40 of the present embodiment. Details of the hard coat film 40 will be described later. Further, in the same figure, in order to clearly distinguish the touch panel member 20 and the hard coat film 40 from each other, they are illustrated apart from each other, but actually, they are used in a state where they are bonded together.

The display device 30 displays an image, and is composed of a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), or the like. In terms of excellent visibility, it is preferable to apply the hard coat film of this embodiment particularly to a liquid crystal display device. The liquid crystal display device may be any of a reflective type, a transmissive type, and a transflective type, and is also a TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, OCB (Optically Compensated Bend, Optically Compensated Birefringence) type. Any driving method such as a VA (Virtical Alignment) type, an IPS (In-Plane Switching) type, or an ECB (Electrically Controlled Birefringence) type may be employed.

The touch panel member 20 forms transparent

conductive films

23 and 24 made of tin-doped indium oxide (ITO) on the surfaces of the two light-transmitting substrates 21 and 22, respectively, so that the transparent

conductive films

23 and 24 face each other. In addition, the light transmissive base materials 21 and 22 are arranged to face each other with a spacer 25 interposed therebetween. A hard coat film 26 for imparting hardness and scratch resistance is provided on the surface of the touch panel member 20 opposite to the display device 30, that is, the surface on the input operation side of the light transmissive substrate 21. . As described above, the hard coat film 26 can be configured by forming a hard coat layer on a cellulose ester film.

According to the above configuration, when the predetermined position of the touch panel member 20 is pressed with a finger or a stylus pen, the pressed transparent conductive film 23 on the input operation side and the transparent conductive film 24 on the display device 30 side come into contact with each other. . Therefore, the input information can be detected by detecting the contact position (position of the pressed part) of the transparent

conductive films

23 and 24.

(About hard coat film on display side)
A hard coat film 40 is bonded to the substrate surface on the image display side of the display device 30 described above. FIG. 2 is an enlarged sectional view showing the hard coat film 40. The hard coat film 40 is an optical film in which a hard coat layer 42 is formed by applying a composition for forming a hard coat layer on a cellulose ester film 41 and curing the composition. The materials of the cellulose ester film 41 and the hard coat layer 42 are as described above. The hard coat film 40 of this embodiment has a mixed layer 43 between the cellulose ester film 41 and the hard coat layer 42.

When the hard coat layer 42 is formed on the cellulose ester film 41, the mixed layer 43 is infiltrated into the cellulose ester film 41 by the solvent contained in the applied hard coat layer forming composition. This is a layer formed by mixing the layers, and is a layer in which the cellulose ester film 41 and the hard coat layer 42 are mixed. This mixed layer 43 can be visually recognized as a difference in contrast, for example, by imaging the cut surface of the hard coat film 40 at a magnification of about 1000 to 5000 with a transmission electron microscope apparatus. Examples of the transmission electron microscope apparatus include H-7650 manufactured by Hitachi High-Technologies Corporation.

In this embodiment, a phthalate ester plasticizer or a phosphate ester plasticizer is contained in the cellulose ester film 41 as a plasticizer for promoting the formation of the mixed layer 43. Since the formation of the mixed layer 43 is promoted by adding the plasticizer to the cellulose ester film 41, the thickness of the mixed layer 43 can be increased as compared with the case where the plasticizer is not added.

In the present embodiment, the plasticizer for promoting the formation of the mixed layer 43 is contained in the cellulose ester film 41 in an amount of 6 wt% to 12 wt%, and the hard coat layer 42 in the cellulose ester film 41 Is contained more on the hard coat layer 42 side than on the opposite side. When the content of the plasticizer is below the lower limit, it is difficult to sufficiently increase the thickness of the mixed layer 43. On the contrary, when the content of the plasticizer exceeds the upper limit, the thickness of the mixed layer 43 increases too much, and the hard coat layer 42 becomes thin, and the hard coat layer 42 is provided with the minimum necessary hardness. It becomes difficult. In addition, since the plasticizer is contained in a large amount on the hard coat layer 42 side in the cellulose ester film 41, the mixed layer 43 can be efficiently formed on the hard coat layer 42 side of the cellulose ester film 41.

As described above, the plasticizer that promotes the formation of the mixed layer 43 is contained in a predetermined amount in the cellulose ester film 41, and is contained in a large amount on the hard coat layer 42 side. While ensuring the minimum hardness, the thickness of the mixed layer 43 to be formed can be increased so that the mixed layer 43 can have an impact absorbing function, and the entire hard coat film 40 can be given flexibility. it can. Thereby, even when the film thickness of the hard coat film 40 is as thin as 15 μm or more and 35 μm or less, the hard coat film 40 has a minimum hardness for preventing scratches in the outermost hard coat layer 42. Cracks due to impact (cracks) can be reduced.

Therefore, as shown in FIG. 1, even when the hard coat film 40 is bonded to the substrate surface of the display device 30 and the touch panel member 20 is further bonded to the hard coat layer 42 side, until the touch panel member 20 is bonded. In addition, while protecting the substrate surface of the display device 30 from being damaged by the hard coat layer 42, after the touch panel member 20 is joined, the hard coat film 40 is less likely to be cracked due to an impact at the time of input on the touch panel member 20. can do.

Further, as described above, the hard coat layer forming composition contains a ketone or acetate solvent, and when the composition is applied onto the cellulose ester film 41, the solvent is a cellulose ester. Infiltrate the film 41 and dissolve. Thereby, the mixed layer 43 can be reliably formed between the hard coat layer 42 and the cellulose ester film 41, and the hard coat film 40 having such a mixed layer 43 can be reliably realized.

Further, the phosphoric acid plasticizer contained in the cellulose ester film 41 is unevenly distributed on one side in the thickness direction (for example, the support side at the time of casting) when the cellulose ester film 41 is formed by the solution casting method. It has the characteristic to do. For this reason, if the plasticizer that promotes the formation of the mixed layer 43 is the above-described phosphoric acid plasticizer, the hard coat layer 42 is formed on the support side during casting with respect to the cellulose ester film 41. In addition, a mixed layer having a predetermined thickness can be efficiently formed between the cellulose ester film 41 and the hard coat layer 42.

Moreover, the content rate of the said plasticizer (plasticizer which promotes formation of the mixed layer 43) in the film thickness part to the depth of 5 micrometers from the surface on the opposite side to the formation side of the hard-coat layer 42 in the cellulose-ester film 41 is as follows. The average content of the plasticizer in the entire cellulose ester film 41 is preferably 10% or more and 50% or less.

When this condition is satisfied, the plasticizer that promotes the formation of the mixed layer 43 is unevenly distributed in the cellulose ester film 41 on the side where the hard coat layer 42 is formed. Therefore, the formation of the mixed layer 43 can be surely promoted by the plasticizer when the hard coat layer forming composition is applied.

The thickness of the mixed layer 43 described above is preferably 0.5% or more and 20% or less in terms of the ratio to the thickness of the hard coat film 40. If the ratio of the thickness of the mixed layer 43 is less than the lower limit, the impact absorbing function in the mixed layer 43 cannot be sufficiently exhibited, and it becomes difficult to reduce cracks due to the impact of the hard coat film 40. On the other hand, when the ratio of the thickness of the mixed layer 43 exceeds the upper limit, the hard coat layer 42 becomes thin, and it becomes difficult to ensure the hardness for preventing damage. Therefore, by making the ratio of the thickness of the mixed layer 43 within the above range, it is easy to reduce cracks due to impact of the hard coat film 40 while ensuring the hardness for preventing the hard coat layer 42 from being damaged. It becomes.

By the way, when the above-mentioned plasticizer, that is, the plasticizer that promotes the formation of the mixed layer 43 is the first plasticizer, the cellulose ester film 41 includes the mixed plastic layer 43 in addition to the first plasticizer. A second plasticizer that promotes formation may be included. However, the second plasticizer is a plasticizer that satisfies the following conditions. That is, the content of the second plasticizer in the film thickness portion from the surface on the opposite side to the formation side of the hard coat layer 42 in the cellulose ester film 41 to the depth of 5 μm is the second plasticity in the entire cellulose ester film 41. It is 80% or more and 120% or less with respect to the average content rate of an agent. As such a 2nd plasticizer, the ethyl phthalyl ethyl glycolate (EPEG) mentioned above can be considered, for example.

In the cellulose ester film 41, since the first plasticizer is unevenly distributed on the hard coat layer 42 forming side, the flexibility tends to decrease on the side opposite to the hard coat layer 42 forming side in the cellulose ester film 41. . However, the content of the second plasticizer on the side opposite to the side on which the hard coat layer 42 is formed in the cellulose ester film 41 is the same as or close to the average content (100%) with respect to the entire cellulose ester film 41. Therefore, the second plasticizer can supplement the flexibility that tends to decrease on the side opposite to the side on which the hard coat layer 42 is formed. Thereby, suppleness can be reliably given to the whole cellulose-ester film 41 and by extension, the hard coat film 40 whole.

In addition, although the example which bonded the hard coat film 40 of this embodiment on the image display surface of the display apparatus 30 was demonstrated above, the position which bonds the hard coat film 40 may be another position. Good. For example, instead of the hard coat film 26 on the outermost surface (input operation side surface) of the touch panel member 20, a hard coat film 40 may be bonded, or the display device 30 in the light transmissive substrate 22 of the touch panel member 20. The hard coat film 40 may be bonded to the surface on the side or the surface on the light transmissive substrate 21 side.

<Example>
Hereinafter, examples of the present embodiment will be described, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless there is particular notice, it shall represent "mass part" or "mass%". Moreover, a comparative example is also shown for comparison with the examples.

(Examples 1 to 20, Comparative Examples 1 to 18)
(Preparation of cellulose ester film 1)
The following materials were sequentially put into a sealed container, the temperature in the container was raised from 20 ° C. to 80 ° C., and the mixture was stirred for 3 hours while maintaining the temperature at 80 ° C. to completely dissolve the cellulose ester. . The silicon oxide fine particles were added dispersed in a solution of a solvent to be added in advance and a small amount of cellulose ester. This dope was filtered using filter paper (Azumi filter paper No. 244, manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope composition 1.
Cellulose triacetate (acetyl group substitution degree 2.95) 100 parts by weight Triphenyl phosphate 8.7 parts by weight (content in cellulose ester film is 8.0% by weight)
Silicon oxide fine particles (Aerosil R972V, manufactured by Nippon Aerosil Co., Ltd.)
0.2 parts by mass Methylene chloride 320 parts by mass Methanol 20 parts by mass Butanol 5 parts by mass

Next, the obtained dope composition 1 was cast on a support having a temperature of 35 ° C. made of a stainless steel endless belt through a casting die kept at a temperature of 35 ° C. to form a web. Next, the web was dried on the support, and the web was peeled from the support with a peeling roll when the residual solvent amount of the web reached 30% by mass. The moving speed of the belt was 40 m / min.

The web after peeling is transported while being dried with 90 ° C drying air in a transport drying process using a plurality of rolls arranged on the top and bottom, and then grips both ends of the web with a tenter and then stretches in the width direction at a temperature of 130 ° C. The film was stretched to 1.1 times the previous size. After stretching with a tenter, the web was dried with a drying air at a temperature of 135 ° C. in a transport drying process using a plurality of rolls arranged vertically.

After heat-treating the web for 15 minutes in an atmosphere with an atmosphere substitution rate of 15 (times / hour) in the drying step, the web was cooled to room temperature and wound up, and the width was 1.5 m, the film thickness was 20 μm, the length was 4000 m, and the refractive index was 1. Forty-nine long cellulose ester films 1 (transparent film substrate 1) were produced. Further, the film was wound by applying a knurling process with a width of 1 cm and an average height of 5 μm at both ends.

The draw ratio in the web conveyance direction immediately after peeling calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times.

The film cross section of the obtained cellulose ester film and the amount of plasticizer on both surfaces were quantified by TOF-SIMS (Time of Flight- Secondary Ion Mass Spectrometry). Thereby, the content of the plasticizer in the part from the surface to the depth of 5 μm on both surfaces of the film was 40% on each surface with respect to the average content of the plasticizer in the total film thickness of the cellulose ester film (this measurement surface (A1 surface)) and 160% (this measurement surface is the B1 surface). The TOF-SIMS measurement was performed by detecting fragments caused by the plasticizer present on the film surface and cross section using, for example, TRIFT II type TOF-SIMS (trade name) manufactured by Phi Evans.

(Preparation of hard coat film 1)
A microgravure coater obtained by filtering the following hard coat layer forming composition 1 as a coating composition on the produced transparent film substrate 1 (cellulose ester film 1) with a polypropylene filter having a pore diameter of 0.4 μm is used. And then applied to the A1 surface of the cellulose ester film 1 and dried at a constant rate drying zone temperature of 50 ° C. and a reduced rate drying zone temperature of 70 ° C., and then nitrogen so that the atmosphere has an oxygen concentration of 1.0% by volume or less. While purging, an ultraviolet lamp was used, the illumination intensity of the irradiated part was 100 mW / cm ² , the irradiation amount was 0.2 J / cm ² , the coating layer was cured to form a hard coat layer, and a 25 μm thick hard coat film was formed. Produced.
[Composition 1 for forming hard coat layer]
73 parts by mass of pentaerythritol tri / tetraacrylate (NK ester A-TMM-3, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Irgacure 184 (Ciba Japan Co., Ltd.) 5 parts by mass Silicone surfactant 1 part by mass (Shin-Etsu Chemical Co., Ltd., trade name: KF-351A)
Acetone 70 parts by weight Methyl acetate 70 parts by weight Propylene glycol monomethyl ether 10 parts by weight

(Preparation of hard coat films 2 to 24)
Except having changed the plasticizer (triphenyl phosphate) and its addition amount in the dope composition 1 as shown in Table 1 and Table 2, it is the same as preparation of the hard coat film 1. FIG.

(Preparation of hard coat films 25-30)
Except for changing the film thicknesses of the cellulose ester film 1 and the hard coat film as shown in Table 2, it is the same as the production of the hard coat film 1.

(Preparation of hard coat film 31)
The coated surface of the hard coat layer forming composition 1 is the same as the production of the hard coat film 1 except that the B1 surface on the back surface side of the cellulose ester film 1 is used.

(Preparation of hard coat film 32)
Except that the coated surface of the hard coat layer forming composition 1 is the B1 surface on the back side of the cellulose ester film 1, it is the same as the production of the hard coat film 2.

(Preparation of hard coat films 33-35)
Except for changing the solvent (coating solution solvent) of the hard coat layer forming composition 1 as shown in Table 2, it is the same as the production of the hard coat film 1.

(Preparation of hard coat films 36-38)
Except for changing the distribution of the plasticizer as shown in Table 2, it is the same as the production of the hard coat film 1. Here, the distribution of the plasticizer means the content of the plasticizer in the film thickness portion from the surface opposite to the hard coat layer forming side in the cellulose ester film to the depth of 5 μm in the entire cellulose ester film. It is shown by the ratio with respect to the average content rate. The distribution of the plasticizer can be changed by changing the moving speed of the belt (support) during casting in the production of the cellulose ester film 1.

(Production of touch panel display devices 1 to 38)
Each of the hard coat films 1 to 38 produced as described above is bonded onto the substrate on the image display surface side of the liquid crystal display device as the display device 30 shown in FIG. 20 were joined to produce touch panel display devices 1 to 38.

(Evaluation by scratch test)
As an abrasion test, the surface of the hard coat film 1 to 38 was reciprocated 10 times while applying a load of 500 g / cm ² on steel wool # 0000, and the number of scratches generated thereby was visually examined. The standard of evaluation by such an abrasion test is as follows.
A: No scratches are observed.
○: 1 to 3 fine scratches are observed.
X: About 4 to 20 fine scratches are observed.

(Evaluation by impact test)
As an impact test for each of the touch panel display devices 1 to 38, a steel ball static pressure test was performed. In other words, a flat steel plate with a width of 2 mm is used to support the four sides of the touch panel display device, and a steel ball with a diameter of 16 mm is pressed 10 times with a load of 40 kgf at a constant speed of 10 mm per minute from the vertical direction against the touch panel display device. The occurrence of cracks in the hard coat film at that time was examined. The criteria for evaluation by the impact test are as follows.
(Double-circle): It was not cracked by 10 times of presses.
○: Cracked once or twice after 10 times of pressing.
X: It cracked 3 times or more by the press of 10 times.

Tables 1 and 2 show the various parameters of the hard coat films 1 to 38 produced as described above and the results of the evaluation by the scratch test, and the results of the evaluation by the impact test of the touch panel display devices 1 to 38. ing. The correspondence relationships between the hard coat films 1 to 38 and the touch panel display devices 1 to 38 and Examples 1 to 20 and Comparative Examples 1 to 18 are as shown in Tables 1 and 2. In Tables 1 and 2, the plasticizer content is indicated by weight% (wt%).

In Tables 1 and 2, AC is acetone, MA is methyl acetate, PGME is propylene glycol monomethyl ether, MEK is methyl ethyl ketone, IPA is isopropyl alcohol, TOL is toluene, TPP is triphenyl phosphate, BDP is biphenyl diphenyl phosphate, DEP is diethyl phthalate, EPEG is ethyl phthalyl ethyl glycolate, PE is an ester compound (end group) obtained by esterifying a plasticizer (adipic acid: phthalic acid = 70: 30) and 1,2-ethanediol. Is acetyl group), and monopet SB is sucrose benzoate (Daiichi Kogyo Seiyaku Co., Ltd.).

In the hard coat films 1 to 24, when TPP or BDP is contained as the first plasticizer (plasticizer 1) in the cellulose ester film, 5 μm from the surface opposite to the hard coat layer forming side in the cellulose ester film. The content rate of the first plasticizer in the film thickness portion up to the depth of 10% or more and 50% or less with respect to the average content rate of the first plasticizer in the whole cellulose ester film, It can be seen that the plasticizer is unevenly distributed on the hard coat layer side.

In addition, when the content of the first plasticizer in the cellulose ester film is 5% by weight, the evaluation of the impact test when the touch panel display device is configured is x, but the content of the first plasticizer is 7% by weight. %, The impact test is evaluated as ◎ (see hard coat films 5, 6, 11, 12). From this, if the content of the first plasticizer is 6% by weight between 5% by weight and 7% by weight, it is estimated that the evaluation of the impact test is ○ between x and ◎. The In addition, when the content of the first plasticizer is 13% by weight, the evaluation of the scratch test is x. When the content of the first plasticizer is 11% by weight, the evaluation of the scratch test is ○. In both contents, the impact test is evaluated as ◎ (see hard coat films 3, 4, 9, and 10). From this, it can be inferred that if the content of the first plasticizer is 12% by weight between 11% by weight and 13% by weight, good results can be obtained in both scratch resistance and impact absorption. .

Further, when a film is produced by applying the composition for forming a hard coat layer on the opposite side of the cellulose ester film from the side on which the first plasticizer is unevenly distributed, such as the hard coat films 31 to 32. The evaluation of the impact test is x. This is because the mixed layer is formed on the side opposite to the side where the first plasticizer is unevenly distributed with respect to the cellulose ester film, so the formation of the mixed layer is not facilitated by the first plasticizer, This is probably because the film could not be formed with a sufficient thickness.

From the above, the first plasticizer is contained in the cellulose ester film in an amount of 6 wt% to 12 wt%, and more on the hard coat layer side than the opposite side of the hard coat layer in the cellulose ester film. By containing, even when the thickness of the hard coat film is as thin as 25 μm, it is possible to reduce the cracks caused by the impact of the hard coat film while ensuring the minimum hardness for preventing scratches in the hard coat layer. It can be said.

Further, referring to the hard coat films 25 to 30, the impact test is evaluated as x when the film thickness of the entire hard coat film is 14 μm, and the impact test is evaluated as ◎ when the film thickness is 16 μm. If it is 15 μm between 14 μm and 16 μm, it is estimated that the evaluation of the impact test is ○ between x and ◎. Therefore, it can be said that the above-described effects can be obtained if the thin hard coat film has a thickness of 15 μm or more and 30 μm or less.

The hard coat films 34 to 35 are prepared using a solvent other than ketones and acetates as the solvent of the hard coat layer forming composition. The touch panel display devices 34 to 35 perform impact tests. Evaluation is ○. On the other hand, in the touch panel display device 1 using the hard coat film 1 produced using the solvent, the impact test is evaluated as ◎. From this, it can be said that it is more desirable from the viewpoint of preventing cracking to produce a hard coat film using a ketone solvent and an acetate ester solvent as the solvent.

Further, in the hard coat films 37 to 38, the distribution of the plasticizer exceeds 50%, and in the touch panel display devices 37 to 38, the impact test is evaluated as “good”. On the other hand, in the touch panel display device 1 using the hard coat film 1 having a plasticizer distribution of 50% or less, the impact test is evaluated as “◎”. From this, it can be said that the distribution of the plasticizer is desirably 50% or less from the viewpoint of preventing cracking of the hard coat film.

Moreover, from Table 1 and Table 2, when the thickness of the mixed layer of the hard coat film exceeds 20% in a ratio to the thickness of the hard coat film, the evaluation by the scratch test becomes x (hard coat film 4, 10, 23). For this reason, it can be said that the ratio of the thickness of the mixed layer is desirably 20% or less. Moreover, when the ratio of the thickness of the mixed layer is 0.4%, the evaluation of the impact test is x (see, for example, the hard coat film 6), but when the ratio of the thickness of the mixed layer is 0.6%, the impact test is performed. Is evaluated as ◯ (see hard coat films 35 and 38). Therefore, if the ratio of the thickness of the mixed layer is 0.5% between 0.4% and 0.6%, an evaluation close to ◯ can be expected as the evaluation of the impact test. Therefore, it can be said that the lower limit of the ratio of the thickness of the mixed layer is desirably 0.5% or more, and more desirably 0.6% or more.

When the thickness of the mixed layer is 0.4% or less as a ratio to the thickness of the hard coat film, the first plasticizer is difficult to say the plasticizer that promotes the formation of the mixed layer. The hard coat films 13 to 20 using monopet SB or PE as the agent are positioned as comparative examples, not examples.

(Preparation of hard coat films 39 to 45)
Next, 5 parts by mass of ethyl phthalyl ethyl glycolate (EPEG) is added as a second plasticizer to the material of the dope composition 1 used in the production of the hard coat film 1, and in the production of a cellulose ester film, Hard coat films 39 to 45 were produced by changing the distribution of the second plasticizer by changing the moving speed of the belt. About other than that, it is the same as that of preparation of the hard coat film 1. FIG.

Table 3 shows the results of evaluation when hard coat films 39 to 45 were subjected to the same scratch test as described above.

From Table 3, the distribution of the second plasticizer, that is, the content of the second plasticizer in the film thickness portion from the surface opposite to the hard coat layer forming side in the cellulose ester film to a depth of 5 μm, It can be seen that if the ratio relative to the average content in the whole cellulose ester film is 78% or more and 122% or less, good results (at least ○) are obtained in the scratch test. Further, it can be seen that if the distribution of the second plasticizer is 82% or more and 118% or less, a better result (）) is obtained in the scratch test (hard coat films 40 to 44). From this, if the distribution of the second plasticizer is 80% or more between 78% and 82% and 120% or less between 118% and 122%, it is marked as において in the scratch test. We can expect to get close results. When the touch panel display devices 39 to 45 were produced using the hard coat films 39 to 45 and subjected to the impact test, it was found that good results (（) were also obtained.

The present invention can be used for a hard coat film bonded to an image display surface of a display device to which a touch panel member is bonded, for example.

DESCRIPTION OF SYMBOLS 10 Touch panel display device 20 Touch panel member 30 Display device 40 Hard coat film 41 Cellulose ester film 42 Hard coat layer 43 Mixed layer

Claims

A hard coat film in which a hard coat layer is formed by applying a composition for forming a hard coat layer on a cellulose ester film and curing the composition,
The film thickness of the hard coat film is 15 μm or more and 35 μm or less,
The plasticizer for promoting the formation of the mixed layer of the cellulose ester film and the hard coat layer is contained in the cellulose ester film in an amount of 6 wt% to 12 wt%, and the hard coat in the cellulose ester film The hard coat film is more contained on the hard coat layer side than on the side opposite to the layer.
The hard coat film according to claim 1, wherein the hard coat layer forming composition contains a ketone or acetate solvent.
3. The hard coat film according to claim 1, wherein the plasticizer is a phosphoric acid plasticizer.
In the cellulose ester film, the content of the plasticizer in the film thickness portion from the surface opposite to the side on which the hard coat layer is formed to a depth of 5 μm is the average content of the plasticizer in the entire cellulose ester film. On the other hand, it is 10% or more and 50% or less, The hard coat film in any one of Claim 1 to 3 characterized by the above-mentioned. *
The hard coat film according to any one of claims 1 to 4, wherein the thickness of the mixed layer is 0.5% or more and 20% or less in a ratio to the thickness of the hard coat film.
When the plasticizer is the first plasticizer,
In addition to the first plasticizer, a second plasticizer for promoting the formation of a mixed layer of the cellulose ester film and the hard coat layer is contained in the cellulose ester film,
In the cellulose ester film, the content of the second plasticizer in the film thickness portion from the surface opposite to the side on which the hard coat layer is formed to a depth of 5 μm is the average of the plasticizer in the entire cellulose ester film. The hard coat film according to any one of claims 1 to 5, wherein the content is 80% or more and 120% or less with respect to the content.
A display device for displaying an image;
A hard coat film bonded to the substrate surface on the image display side of the display device;
A touch panel display device having a touch panel member joined to the display device via the hard coat film,
The said hard coat film is comprised with the hard coat film in any one of Claim 1 to 6, The touchscreen display apparatus characterized by the above-mentioned.