JP2009003465A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antiglare hard coat film in which a scattering characteristic of transmitted light of parallel light made incident on a film or a sheet is controlled and glaring is improved and to provide its manufacturing method. <P>SOLUTION: The antiglare hard coat film has minute rugged structure on one side of a transparent plastic base material. The scattering characteristic of light passed through the antiglare hard coat film is that light quantity distribution from a center point of an optical axis of transmitted light when parallel light is made incident from either one surface becomes not more than 25 times a haze value defined in Japanese Industrial Standard (K7105) toward half value width obtained by using approximation coefficients when approximated by a Gaussian curve G(z) expressed by formula a: G(z)= k<SB>0</SB>+ k<SB>1</SB>expä[-(z-k<SB>2</SB>)/k<SB>3</SB>]<SP>2</SP>} (wherein k<SB>0</SB>, k<SB>1</SB>, k<SB>2</SB>, k<SB>3</SB>are approximation coefficients and half value width is 1.66k<SB>3</SB>). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to various display devices (herein, the display device is also referred to as a display), in particular, on the screen of a display device represented by LCD, CRT, PDP, ECD, ELD, FED or LED. It is related with the anti-glare hard coat film suitable for exhibiting anti-glare property by providing, and its manufacturing method.

  The “film” in the antiglare hard coat film of the present invention means a so-called film shape, a so-called sheet shape, and any of these cases.

  In various displays such as LCDs and CRTs as described above, light is incident on the screen from the outside, and this light is reflected on the surface of the screen, making it difficult to view the displayed image. Preventing these problems (this is simply referred to as “anti-glare” in the present specification) has become an increasingly important issue particularly with the rapid spread and enlargement of flat panel displays in recent years. In order to solve this problem, liquid crystal displays do not emit light with confidence, and unless a backlight is built in, it is necessary to display images using external light. Come.

Conventionally, as a means for imparting antiglare properties, it is possible to use a sandblasting method, an embossing method, or a film or sheet having a concavo-convex structure formed on its surface by various methods such as blending inorganic and organic fine particles. Attempts to provide an antiglare layer on a display device have been proposed. The surface of the screen is not only used to provide a fine texture to the display screen, to eliminate the rough feeling when touching the screen, but also to prevent the glare associated with higher display resolution. There is an increasing demand for further miniaturization of the concavo-convex structure (this fine concavo-convex structure on the surface is simply referred to as a fine concavo-convex structure in this specification).
That is, the glare of the screen, which is caused by the difference in level even when trying to prevent it by the fine uneven structure formed on the surface of the antiglare hard coat film, is, for example, in the case of an LCD with a backlight. Based on refraction and scattering when light from a backlight source passes through a color filter with a finer pitch than before and through an anti-glare hard coat film with a fine relief structure. The degree of glare is influenced not only by the degree of miniaturization of the fine concavo-convex structure surface, but also by the shape of the material forming the fine concavo-convex structure, the difference in refractive index between the resin and the like.

However, as a method for evaluating the glare feeling, sensory evaluation such as visual evaluation when an antiglare hard coat film is attached to the display surface is common.
In general, the lower the degree of miniaturization of the fine concavo-convex structure provided on the hard coat film, that is, the rougher the texture, and the resin material and fine concavo-convex that form the anti-glare hard coat film. It is known that the greater the difference in refractive index from the material forming the structure, the higher the degree of scattering when the light from the light source passes through the hard coat film with a fine concavo-convex structure. It has been. Accordingly, there is a need for an anti-glare hard coat film that can cope with higher definition of the display, controls the scattering of light from the light source, and has an improved glare feeling.

  The present invention has been made in order to solve the problems required for the film or sheet of the conventional technology as described above, and the scattering characteristics of transmitted light of parallel light incident on the film or sheet are controlled. An object of the present invention is to provide an antiglare hard coat film with improved glare and a method for producing the same.

The means provided by the present invention in order to solve the above-mentioned problem is the invention shown in claim 1 and is an anti-glare hard coat film having a fine concavo-convex structure on at least one surface of a substrate made of transparent plastic. In
The scattering characteristics of the light transmitted through the antiglare hard coat film are as follows. The light quantity distribution from the center point of the optical axis of the transmitted light when parallel light is incident from one of the surfaces is represented by the following [formula a]: The anti-glare property is less than 25 times the haze value defined in JIS (K7105) with respect to the half-value width obtained using the approximation coefficient when approximated by the Gaussian curve G (z) shown in FIG. It is a hard coat film.
G (z) = k ₀ + k ₁ exp {[− (z−k ₂ ) / k ₃ ] ² } (formula a)
Here, k ₀ , k ₁ , k _2, and k ₃ are approximate coefficients, respectively, and the half-value width obtained therefrom is 1.66 k ₃ .

According to this, in an anti-glare hard coat film having a fine concavo-convex structure on at least one surface of a substrate made of transparent plastic, the light was transmitted through the film, and the parallel light was provided with fine concavo-convex JIS (K7105) defines the full width at half maximum obtained from the approximation coefficient when the light intensity distribution from the center point of the transmitted light is approximated by the Gaussian curve G (z). It is evaluated from the correlation with the haze value.
Here, parallel light is incident from the back surface of a base material made of a transparent plastic provided with fine irregularities, and the approximation coefficient when the light quantity distribution from the center point of the transmitted light is approximated by the Gaussian curve G (z). If the half-value width required more than 25 times the haze value defined in JIS (K7105), the light from the light source is greatly affected by the scattering of the fine concavo-convex structure and / or the fine concavo-convex structure material, resulting in glare. The feeling is increased, which is not preferable.

  More preferably, it is the invention shown in claim 2, and based on the antiglare hard coat film of claim 1, at least one component of the resin composition constituting the material of the antiglare hard coat film, Hardness required for a hard coat film used for a display surface etc., scratch resistance, characterized by being one of an ultraviolet curable polymer, an ultraviolet curable oligomer, or an ultraviolet curable monomer, Properties such as chemical resistance can be obtained.

  Moreover, according to the invention shown in claim 3, with the antiglare hard coat film of claim 1 as a basic configuration, at least one component of the resin composition constituting the material of the antiglare hard coat film is an electron. A hard coat used on a display surface or the like, similar to the invention shown in claim 2, characterized in that it is one of a line curable polymer, an electron beam curable oligomer, and an electron beam curable monomer. Properties such as hardness, scratch resistance and chemical resistance required for the film can be obtained.

  Moreover, according to the invention shown in claim 4, based on the antiglare hard coat film according to any one of claims 1 to 3, the fine concavo-convex structure is at least an organic or inorganic fine particle It is formed using.

Then, as shown in claim 5, there is provided a method for producing the antiglare hard coat film according to any one of claims 1 to 3, wherein the active energy ray curable type is applied to at least one side of a substrate made of a transparent plastic. A resin is applied, and this is irradiated with an active energy ray to cure the active energy ray curable resin to form an active energy ray curable resin coating layer. Thereafter, the active energy ray curable resin coating layer is applied to the active energy ray curable resin coating layer. The method for producing an antiglare hard coat film is characterized by applying either a sandblasting method or an embossing method.
Known techniques can be applied to the sandblasting method and embossing.

  Furthermore, as shown in claim 6, there is provided a method for producing an antiglare hard coat film according to any one of claims 1 to 4, wherein fine particles comprising an active energy ray-curable resin are dispersed in a dispersion medium. An active energy ray-curable resin is applied by applying the applied coating liquid to at least one surface of a substrate made of a transparent plastic, and then curing the surface by applying active energy rays to the surface to which the coating liquid is applied. A coating layer is formed.

  In general, as the fine particles, inorganic or organic fine particles can be preferably used, and when a coating layer is formed by applying an active energy ray-curable resin (in some cases, the fine particles are dispersed) to form a coating layer. A known coating technique can be preferably used.

  A hard coat film provided with an active energy ray-curable resin coating layer on at least one surface of a transparent plastic substrate according to the present invention, wherein the scattering characteristics of transmitted light of parallel light incident on the film or sheet are controlled, It was possible to provide an antiglare hard coat film or sheet having an improved glare feeling. Especially when used on the display surface, the fine uneven structure prevents the reflection of external light, and the light from the backlight light source of the display transmits through the fine pitch of the color filter, which is becoming more finely defined. The glare feeling based on refraction and scattering when passing through a film having a structure can be improved by controlling the scattering characteristics of incident parallel light.

  According to the present invention, it is possible to provide an antiglare hard coat film having a fine concavo-convex structure on the surface, controlled scattering characteristics of incident parallel light transmitted light, and improved glare, and a method for producing the same. It was.

  Hereinafter, the present invention will be described in detail. First, the constituent materials of the antiglare hard coat film (or sheet) and the method for producing the antiglare hard coat film (or sheet) will be described in order.

<Constituent material of antiglare hard coat film>
FIG. 1 shows an outline of an antiglare hard coat film according to the present invention.
The material of the transparent plastic film or sheet as the substrate 1 is not particularly limited, and can be appropriately selected from known transparent plastic films or sheets having appropriate mechanical rigidity.
Specific examples include polyester, polyethylene, polypropylene, cellophane, triacetyl cellulose, diacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, polystyrene, polycarbonate, polymethylpentene, polysulfone. , Polyether ketone, acrylic, nylon, fluororesin, polyimide, polyetherimide, polyether sulfone, etc., but in the present invention, at present, particularly triacetyl cellulose film and uniaxial stretching In addition to being excellent in transparency, polyester is preferable in that it has no optical anisotropy.

The active energy ray-curable resin for forming the hard coat layer 2 is not particularly limited, and the active energy ray is a resin that gives a coating film having a pencil hardness of H or higher as defined in JIS (K5400) by ultraviolet ray or electron beam curing. It can be used arbitrarily if it exists.
Examples of such UV curable resins are synthesized from polyfunctional acrylate resins such as acrylic acid or methacrylic acid ester of polyhydric alcohol, diisocyanate, polyhydric alcohol, and hydroxyester of acrylic acid or methacrylic acid. Examples of such polyfunctional urethane acrylate resins.
In addition to these, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be suitably used as necessary. .

  In addition, as reaction diluents for these resins, 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol (meta) having a relatively low viscosity are used. ) Bifunctional or higher monomers and oligomers such as acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, neopentyl glycol di (meth) acrylate, and monofunctional monomers For example, acrylic acid esters such as N-vinylpyrrolidone, ethyl acrylate and propyl acrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate Derivatives such as methacrylate, hexyl methacrylate, isooctyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, nonylphenyl methacrylate, tetrahydrofurfuryl methacrylate, and its caprolactone modified product, styrene, α-methylstyrene, acrylic Acids and the like and mixtures thereof can be used.

  In the present invention, when the active energy ray is ultraviolet light, it is necessary to add a photosensitizer (radical polymerization initiator), such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl methyl. Benzoins such as ketals and alkyl ethers thereof; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone; anthraquinones such as methylanthraquinone, 2-ethylanthraquinone, 2-aminoanthraquinone Thioxanthones such as thioxanthone, 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone; ketones such as acetophenone dimethyl ketal and benzyl dimethyl ketal Lumpur like; benzophenone, and the like 4,4-bis benzophenones such as methylamino benzophenone and azo compounds.

These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and metadiethanolamine; benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate, etc. It can be used in combination with a photoinitiator aid or the like.
The usage-amount of an organic peroxide or a photoinitiator is 0.5-20 weight part with respect to 100 weight part of polymerization components of the said resin composition, Preferably it is 1-15 weight part.

  The fine concavo-convex structure 3 on the hard coat film surface can be formed by various methods such as sand blasting, embossing, or adjusting the blending of inorganic or organic fine particles. As the inorganic or organic fine particles, any fine particles that retain good transparency in the active energy ray-curable resin can be used arbitrarily.

  In general, fine particles made of silica, alumina, titania, zirconia, etc. are used as the inorganic fine particles. Among them, silica particles, particularly synthetic silica particles are preferable in terms of antiglare properties, resolution, hard coat properties and the like. . Both regular and amorphous silica can be used. Conductive transparent fine particles such as tin oxide, indium oxide, cadmium oxide, and antimony oxide can also be used regardless of imparting charging property.

  Further, as the organic fine particles, hard fine particles having an appropriate cross-linked structure inside the particles and not swelled by an active energy ray-curable resin, a monomer, a solvent, or the like can be used. For example, particle internal cross-linked styrene resin, styrene-acrylic copolymer resin, acrylic resin, divinylbenzene resin, silicone resin, urethane resin, melamine resin, styrene-isoprene resin, benzoguanamine resin, other reactivity A microgel or the like can be used. The blending amount of the transparent fine particles is 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight per part by weight of the active energy ray-curable resin.

  Moreover, a well-known general coating additive can be mix | blended as needed. For example, silicone and fluorine additives that impart leveling, surface slip properties, etc. are effective in preventing scratches on the surface of the cured film, and in the case of using ultraviolet rays as active energy rays, the additives described above Bleeding to the air interface can reduce the inhibition of curing of the resin by oxygen, and an effective degree of curing can be obtained even under low irradiation intensity conditions. These addition amounts are suitably 0.01 to 0.5 parts with respect to 100 parts by weight of the active energy ray-curable resin.

<Method for producing antiglare hard coat film>
The method for applying the hard coat layer is arbitrary, but in the production stage, a roll coater, a reverse roll coater, a gravure coater, a knife coater, a bar coater or the like is generally used.

When ultraviolet rays are used as the active energy ray source, a light source such as a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, or a xenon arc can be used.
A metal halide lamp is generally used when a filler is included or a thick film is cured.

  Also, when curing using electron beam, it is emitted from various electron beam accelerators such as cockloftwald type, bandecraft type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, high frequency type, etc. An electron beam having an energy of 50 to 1000 keV, preferably 100 to 300 keV can be used.

  The antiglare hard coat film of the present invention has a structure composed of two layers, the transparent plastic substrate and the hard coat layer. A necessary amount of inorganic or organic fine particles are added to the resin of the hard coat layer by a known dispersion method such as a disper mixer or a sand mill, and the film thickness after curing is 0.5 μm or more, preferably 10 μm or less. After processing, it is cured by irradiation with active energy rays.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. The “parts” and “%” are based on weight unless otherwise specified.

<Hard coat layer>
The electron beam curable coating composition shown in the following formulation was prepared according to the procedure described below. First, in a mixed solvent of toluene / 2-butanone = 1/1, silica particles having average particle diameters of 1.9 μm, 2.5 μm, 3.5 μm, 4.5 μm and 5.0 μm, respectively, were dispersed. The silica dispersion liquid was prepared by performing high-speed stirring using a mixer, and each coating liquid sample in Examples 1 to 5 was prepared.
Next, each silica dispersion was gradually added to the mixed solution of the hexafunctional urethane acrylate oligomer and trimethylolpropane triacrylate while stirring.

Hexafunctional urethane acrylate oligomer 40 parts (trade name: U-6HA, manufactured by Shin-Nakamura Chemical Co., Ltd.)
60 parts of trimethylolpropane triacrylate (trade name: Aronix M-309, manufactured by Toa Gosei Co., Ltd.)
Toluene 50 parts 2-butanone 50 parts Silica 5 parts (Example 1 / trade name: Sylysia 530, particle size 1.9 μm,
Example 2 / Product name: Sylysia 436, particle size 2.5 μm,
Example 3 / Product name: Sylysia 445, particle size 3.5 μm,
Example 4 / Product name: Sylysia 446, particle size 4.5 μm,
Example 5 / Product name: Sylysia 456, particle size 5.5 μm,
(All are made by Fuji Silysia)

  Next, after applying the electron beam curable coating composition on one side of a triacetylcellulose film having a thickness of 80 μm with a wire bar and evaporating the solvent, a coating layer having a thickness of about 2.5 μm is formed. A hard coat layer was prepared by curing an electron beam with an acceleration voltage of 200 keV from the coating film side under the condition of an absorbed dose of 3 Mrad.

<Evaluation method>
About the obtained anti-glare hard coat film, the haze value of the hard coat film in which the silica of each particle size was blended was measured. The measuring device is a Nippon Denshoku haze meter, SZ-Σ90.
About these anti-glare hard coat films, the scattering characteristics of transmitted light when a He—Ne laser was transmitted through the film were evaluated by the following optical system. FIG. 1 is a schematic conceptual diagram showing the situation at that time.
In a dark room, a He—Ne laser (manufactured by MELLES GRAOT Co., Ltd., wavelength 543.5 nm) was converted into parallel light with a light diameter of 5 mmφ using a plano-concave lens having a focal length of 90 mm and a plano-convex lens having a focal length of 500 mm. At this time, an ND filter was inserted between the two lenses, and the amount of light was 40% of the total light.
Such incident light was incident from the back side of the antiglare hard coat film, and the scattered state of transmitted light projected on a black plate at a distance of 72 cm from the film position was photographed with a CCD camera. The captured image was digitized, the light amount distribution on the central axis was extracted, and the half width obtained from the approximation coefficient when approximated by the Gaussian curve G (z) shown in the above [Formula a] was calculated.

Here, if the amount of light of the He—Ne laser exceeds 40%, the amount of light in the vicinity of the center point corresponding to the incident light diameter of the transmitted light becomes extremely large, making it difficult to evaluate the light amount distribution of the scattered light. Conversely, if the amount of light of the He—Ne laser is less than 40%, the intensity of the scattered light projected on the black plate is weakened, and the reliability of the light amount distribution may be reduced.
The incident light diameter was set to 5 mm because it is difficult to obtain the scattering characteristics of a film that is an aggregate of fine concavo-convex structures when the area through which incident light passes is extremely small.
In addition, a hard coat film in which silica of each particle size was actually blended was pasted on a display surface having a 10.4 inch color filter dot pitch of 0.33, and the glare was visually confirmed.

<Result of evaluation>
The haze value of the hard coat film in which silica of each particle size was blended was a value around 10%.
The half-value width of the light amount distribution of transmitted light when a He—Ne laser is incident on each of these films from the back is 152 for silica with an average particle diameter of 1.9 μm, 223 for silica with an average particle diameter of 2.5 μm, It was 254 for silica with a particle size of 3.5 μm, 280 for silica with an average particle size of 4.5 μm, and 312 for silica with an average particle size of 5.5 μm.
In a film blended with silica having an average particle diameter of 1.9 μm, even if the amount of light of the He—Ne laser is 40% of the total light, the scattering is small and the amount of light near the center point corresponding to the incident light diameter is around it. Compared with the amount of scattered light, it was remarkably large. For this reason, the light quantity at the center point was set to 100, and evaluation was performed using a half-value width obtained from an approximation coefficient when approximated by a Gaussian curve G (z).
The value obtained by dividing the half-value width by the haze value, and the glare when the hard coat film is actually pasted on the display surface, are the glare of a film containing silica having an average particle size of 5.5 μm. Table 1 shows the results of evaluation with a score of 10 with a decrease in glare.

  As a result, the half-value width increases as the average particle diameter of silica increases, and a hard coat film containing silica having an average particle diameter of 1.9 μm and 2.5 μm is 25 or less when the value is divided by the haze value. It was found that the feeling of glare when bonded to the display surface was greatly improved.

The schematic of the optical system used for the Example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... He-Ne light source 2 ... Plano-concave lens 3 ... Filter 4 ... Plano-convex lens 5 ... Hard coat film 6 ... Black plate

Claims (6)

In an anti-glare hard coat film having a fine concavo-convex structure on at least one side of a substrate made of transparent plastic,
The scattering characteristics of the light transmitted through the antiglare hard coat film are as follows. The light quantity distribution from the center point of the optical axis of transmitted light when parallel light is incident from one of the surfaces is expressed by the following [formula a]: The anti-glare hardware characterized by being less than 25 times the haze value defined in JIS (K7105) with respect to the half-value width obtained using the approximation coefficient when approximated by the Gaussian curve G (z) shown Coat film.
G (z) = k ₀ + k ₁ exp {[− (z−k ₂ ) / k ₃ ] ² } (formula a)
Here, k ₀ , k ₁ , k _2, and k ₃ are approximate coefficients, respectively, and the half-value width obtained therefrom is 1.66 k ₃ .   The at least one component of the resin composition constituting the material of the antiglare hard coat film is any one of an ultraviolet curable polymer, an ultraviolet curable oligomer, and an ultraviolet curable monomer. The antiglare hard coat film described in 1.   At least one component of the resin composition constituting the material of the antiglare hard coat film is any one of an electron beam curable polymer, an electron beam curable oligomer, and an electron beam curable monomer. The antiglare hard coat film according to claim 1.   The antiglare hard coat film according to any one of claims 1 to 3, wherein the fine concavo-convex structure is formed using at least either organic or inorganic fine particles. Apply an active energy ray-curable resin to at least one side of a substrate made of transparent plastic,
This is irradiated with active energy rays to cure the active energy ray curable resin to form an active energy ray curable resin coating layer,
Thereafter, the anti-glare hard coat film according to any one of claims 1 to 3 is produced by applying either a sandblasting method or an embossing method to the active energy ray-curable resin coating layer. A method for producing an antiglare hard coat film characterized by comprising: A coating liquid in which fine particles made of an active energy ray-curable resin are dispersed in a dispersion medium is applied to at least one surface of a base material made of transparent plastic,
After that, the active energy ray-curable resin coating layer is formed by irradiating the surface on which the coating liquid has been applied by irradiating active energy rays, thereby preventing the prevention according to any one of claims 1 to 4. A method for producing an antiglare hard coat film, comprising producing a dazzling hard coat film.

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