JP2013200332A - Display element surface film and display element with surface member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display element surface film that can satisfy all of antiglare property, Newton's ring prevention property and sparkle prevention property at the same time.SOLUTION: A display element surface film has a functional layer on a transparent base material, where the functional layer includes a binder component and a matting agent. The binder component contains an ionizing radiation curable resin, and contains a thermoplastic resin and/or thermosetting resin with glass-transition temperature of 45°C or higher and a weight-average molecular weight of 70,000 or more. Further, a weight ratio of each component in the binder component for the ionizing radiation curable resin is 50 wt.% or more and less than 85 wt.% and for the thermoplastic and/or thermosetting resin is over 15 wt.% and 50 wt.% or less, and a variation coefficient of particle size distribution for the matting agent is 15% or less.

Description

  The present invention relates to a film used on the front surface of various display elements such as a liquid crystal display element, a CRT display element, a plasma display element, and an EL display element, and a display element with a surface member including the film.

  Conventionally, on a display element such as a liquid crystal display element or a plasma display element, the surface thereof is protected on the substrate in order to protect the surface and prevent difficulty in viewing due to glare caused by reflection of external light on the screen. An antiglare film having a surface unevenness treatment is used. And as a surface uneven | corrugated process performed on such a base material, the glare-proof layer containing the particle | grains used as a matting agent is generally used.

  However, as a result of advancement of high definition of various display elements, when a conventional antiglare film having an antiglare layer containing such a matting agent is used on the display element, particles contained in the antiglare layer As a result of the lens shape formed around the center, a glare phenomenon called sparkle occurs, and a problem arises in that a high-definition color screen appears glare.

  Moreover, as a surface member provided on a display element, there exist a touch panel other than the anti-glare film mentioned above. These surface members have a problem that Newton rings occur due to a partial narrowing of the distance between the surface member and the display element and the distance between the members constituting the surface member. For this reason, although the material which comprises a surface member is provided with the Newton ring prevention layer containing a mat agent, the problem (generation of a sparkle) similar to the anti-glare layer mentioned above has arisen.

  As described above, a matting agent is necessary for developing antiglare properties and Newton ring preventing properties. However, sparkle is generated by a lens formed around the matting agent, and antiglare properties or Newtonian properties are generated. It was difficult to satisfy both the ring prevention property and the sparkle prevention property at the same time.

  In order to solve this problem, means for adding a resin component other than the ionizing radiation curable resin to the Newton ring prevention layer (Patent Document 1), and increasing the coefficient of variation of the particle size distribution of the matting agent in the Newton ring prevention layer. Means (Patent Document 2) is disclosed.

  The invention of Patent Document 1 reduces the lens formed around the matting agent by making the shape of the “swell” formed by the ionizing radiation curable resin slightly gentle with other resin components. Is a solution. The invention of Patent Document 2 solves the problem by preventing light from being uniformly scattered by a matting agent having a uniform particle diameter by using a matting agent having a varying particle diameter.

Japanese Patent Laying-Open No. 2005-265863 (paragraph numbers 0027 and 0043) JP 2005-265864 A (paragraph number 0027)

  However, the inventions of Patent Documents 1 and 2 have not always been able to prevent sparkle with respect to color display elements that have been further refined in recent years.

  Then, an object of this invention is to provide the film for display element front surfaces which can satisfy anti-glare property, Newton ring prevention property, and sparkle prevention property simultaneously.

  The display element front film of the present invention that solves the above problems has a functional layer on a transparent substrate, and the functional layer includes a binder component and a matting agent, and the binder component is an ionizing radiation curable resin. And a thermoplastic resin and / or a thermosetting resin having a glass transition temperature of 45 ° C. or more and a weight average molecular weight of 70,000 or more, and the weight ratio of each component in the binder component is such that the ionizing radiation curable resin is 50 wt% or more and less than 85 wt%, the weight ratio of the thermoplastic resin and / or thermosetting resin is more than 15 wt% and 50 wt% or less, and the matting agent has a variation coefficient of particle size distribution of 15 % Or less.

  The display element front film of the present invention is characterized in that the average particle diameter of the matting agent is 0.5 to 10 μm.

  In the display element front film of the present invention, the functional layer is an antiglare layer or a Newton ring prevention layer.

  Moreover, the display element with a surface member of the present invention has a surface member on the display element, and the display element front film of the present invention is included in at least a part of the surface member. is there.

  In the present invention, the “coefficient of variation in particle size distribution” and “average particle size” are values calculated by the Coulter counter method.

  According to the display element front film of the present invention, the antiglare property and the sparkle prevention property can be satisfied at the same time.

Sectional drawing which shows one Embodiment of the film for display element front surfaces of this invention Sectional drawing which shows an example of the conventional film for display element front surfaces Sectional drawing which shows one Embodiment of the display element with a surface member of this invention Sectional drawing which shows other embodiment of the display element with a surface member of this invention.

  First, the display element front film of the present invention will be described. The display element front film of the present invention has a functional layer on a transparent substrate, and the functional layer includes a binder component and a matting agent, and the binder component includes an ionizing radiation curable resin, a glass transition temperature, and the like. A thermoplastic resin and / or a thermosetting resin having a weight average molecular weight of 70,000 or more and a weight ratio of each component in the binder component is 50% by weight or more of the ionizing radiation curable resin. Less than wt%, the weight ratio of the thermoplastic resin and / or thermosetting resin is more than 15 wt% and 50 wt% or less, and the matting agent has a variation coefficient of particle size distribution of 15% or less. It is characterized by.

  FIG. 1 is a cross-sectional view showing an embodiment of a display element front film 1 of the present invention. FIG. 1 has a functional layer 12 including a binder component 121 and a matting agent 122 on a transparent substrate 11.

  Examples of the transparent substrate include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, triacetyl cellulose, acrylic, and the like. Among these, a polyethylene terephthalate film that has been stretched, in particular biaxially stretched, is preferred because of its excellent mechanical strength and dimensional stability.

  As the transparent base material, those having improved adhesion to the functional layer by subjecting the surface to corona discharge treatment or providing an easy adhesion layer are also preferably used. The thickness of the transparent substrate is generally 25 to 500 μm, preferably 50 to 200 μm.

  Examples of the functional layer include an antiglare layer and a Newton ring prevention layer. As such a functional layer, a layer containing a binder component and a matting agent is used.

  The binder component of the functional layer includes an ionizing radiation curable resin. The ionizing radiation curable resin can be formed from a photopolymerizable prepolymer that can be crosslinked and cured by irradiation with ionizing radiation (ultraviolet ray or electron beam). An acrylic prepolymer having at least one acryloyl group and having a three-dimensional network structure by crosslinking and curing is particularly preferably used. As the acrylic prepolymer, urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate, polyfluoroalkyl acrylate, silicone acrylate and the like can be used. Furthermore, these acrylic prepolymers can be used alone, but it is preferable to add a photopolymerizable monomer in order to improve the cross-linking curability and further improve the hardness of the functional layer.

  As photopolymerizable monomers, monofunctional acrylic monomers such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, butoxyethyl acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol One kind of bifunctional acrylic monomer such as diacrylate, polyethylene glycol diacrylate, hydroxypivalate ester neopentyl glycol diacrylate, etc., or polyfunctional acrylic monomer such as dipentaerythritol hexaacrylate, trimethylpropane triacrylate, pentaerythritol triacrylate, or the like Two or more are used.

  The functional layer preferably uses additives such as a photopolymerization initiator and a photopolymerization accelerator in order to cure the above-described photopolymerizable prepolymer and photopolymerizable monomer with ultraviolet rays. Examples of the photopolymerization initiator include acetophenone, benzophenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α-acyloxime ester, thioxanthone and the like.

  Further, the photopolymerization accelerator can reduce the polymerization obstacle due to air at the time of curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. can give.

  Further, an ionizing radiation curable organic-inorganic hybrid resin may be used as the ionizing radiation curable resin.

  If the functional layer contains a matting agent and an ionizing radiation curable resin as a binder component, a “swell” occurs around the matting agent to form a lens shape (FIG. 2) and sparkle occurs. End up. Therefore, in the present invention, the ionizing radiation curable resin contains a thermoplastic resin and / or a thermosetting resin having a glass transition temperature of 45 ° C. or more and a weight average molecular weight of 70,000 or more, thereby suppressing the occurrence of swell ( Fig. 1) prevents sparkle. The reason for producing such an effect is considered as follows.

  First, in the case of an ionizing radiation curable resin alone, it is considered that “undulation” is formed by flowing in the process of drying and curing the resin. When a thermoplastic resin and / or a thermosetting resin having a glass transition temperature of 45 ° C. or higher and a weight average molecular weight of 70,000 or higher is added thereto, the flow of the ionizing radiation curable resin is suppressed, and the occurrence of “swell” is suppressed. it is conceivable that.

  Examples of such thermoplastic resins and / or thermosetting resins include polyester acrylate resins, polyurethane acrylate resins, epoxy acrylate resins, polyester resins, acrylic resins, polycarbonate resins, epoxy resins, and cellulose resins. And acetal resins, vinyl resins, polyethylene resins, polystyrene resins, polypropylene resins, polyamide resins, polyimide resins, melamine resins, phenol resins, silicone resins, fluorine resins, and the like. When a thermoplastic resin and a thermosetting resin are compared, a thermoplastic resin is preferable in that the surface shape can be easily adjusted and the handleability is excellent.

  Further, a (meth) acryloyl group may be introduced into a thermoplastic resin or a thermosetting resin. By introducing a (meth) acryloyl group, it can be firmly bonded to an ionizing radiation curable resin.

  As the thermoplastic resin and / or thermosetting resin, those having a glass transition temperature of 45 ° C. or higher and a weight average molecular weight of 70,000 or higher are used as described above. Here, the glass transition temperature of the thermoplastic resin and / or thermosetting resin is preferably 80 ° C. or higher, and more preferably 90 ° C. or higher. Moreover, it is preferable that the weight average molecular weight of a thermoplastic resin and / or a thermosetting resin is 80000 or more.

  The weight ratio of the ionizing radiation curable resin in the binder component is 50% by weight or more and less than 85% by weight. Moreover, the weight ratio of the thermoplastic resin and / or thermosetting resin in the binder component is more than 15% by weight and 50% by weight or less. By setting the amount of the thermoplastic resin and / or thermosetting resin to exceed 15% by weight, the occurrence of swell can be sufficiently suppressed to prevent sparkle, and the thermoplastic resin and / or thermosetting resin can be used. By setting it as 50 weight% or less, the fall of the coating-film intensity | strength by containing a thermoplastic resin and / or a thermosetting resin more than necessary can be prevented.

  The weight ratio of the ionizing radiation curable resin in the binder component is preferably 60% by weight or more at the lower limit, preferably 80% by weight or less at the upper limit, and more preferably 75% by weight or less. . The weight ratio of the thermoplastic resin and / or thermosetting resin in the binder component is preferably 20% by weight or more at the lower limit, more preferably 25% by weight or more, and 40% by weight or less at the upper limit. It is preferable that

  Matting agents include calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, silica, kaolin, clay, talc and other inorganic particles, acrylic resin particles, polystyrene resin particles, polyurethane resin particles, polyethylene resin particles, benzoguanamine resin particles And resin particles such as epoxy resin particles. As such fine particles, spherical fine particles are preferably used from the viewpoints of handleability and ease of control of the surface shape. Further, the resin particles are suitable in that the difference in refractive index from the binder component can be easily brought close, the occurrence of sparkles can be easily prevented, and the transparency is hardly hindered.

In the present invention, a matting agent having a particle diameter distribution variation coefficient of 15% or less, preferably 10% or less is used. By setting the coefficient of variation of the particle size distribution of the matting agent to 15% or less, it is possible to prevent the occurrence of sparkles due to large local convex portions. The variation coefficient of the particle size distribution of the fine particles is a value indicating a variation state of the particle size distribution of the fine particles, and is a percentage of a value obtained by dividing the standard deviation of the particle size distribution by the average particle size.
Coefficient of variation = (square root of unbiased variance) / (arithmetic mean value) × 100%

  Although the average particle diameter of the matting agent varies depending on the thickness of the functional layer, it cannot be generally stated, but is preferably 0.5 μm or more, and more preferably 1 μm or more. Moreover, since the average particle diameter of the matting agent tends to induce sparkle when it is too large, it is preferably 10 μm or less, more preferably 8 μm or less.

  The content of the matting agent is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more with respect to 100 parts by weight of the binder component. Moreover, since there exists a tendency which induces a sparkle when there is too much content of a mat agent, 5 weight part or less is preferable with respect to 100 weight part of binder components, 3 weight part or less is more preferable, and 1 weight part or less is further. preferable.

  In the functional layer, additives such as a leveling agent, an ultraviolet absorber and an antioxidant may be added.

  The functional layer can be formed by applying a composition containing the binder component and the matting agent constituting the functional layer described above onto a transparent substrate, drying, and irradiating with ionizing radiation.

  In order to prevent sparkle, the display element front film preferably has a total light transmittance (JIS K7361-1: 1997) of 90% or more and a haze (JIS K7136: 2000) of 10% or less.

  Next, the display element with a surface member of the present invention will be described. The display element with a surface member of the present invention has a surface member on the display element, and the display element front film of the present invention is included in at least a part of the surface member.

  Examples of the display element include a liquid crystal display element, a CRT display element, a plasma display element, and an EL display element.

  Examples of the surface member include a protective plate, a touch panel, and a polarizing plate. In the present invention, the above-described film for a display element front surface of the present invention is included in at least part of these surface members.

  For example, when the surface member is the protective plate 2, the structure in which the display element front film 1 of the present invention is laminated as the antiglare film on the surface side of the protective plate 2 (FIG. 3), on the back side of the protective plate 2, The structure (FIG. 4) which laminated | stacked the film 1 for display element front surfaces of this invention as a Newton ring prevention film is mention | raise | lifted. Moreover, you may provide the film for display element front surfaces of this invention on a display element as a protective plate which has anti-glare property and / or Newton ring prevention property.

  Moreover, when the surface member is the touch panel 2, a configuration in which the display element front film 1 of the present invention is laminated as an antiglare film on the surface side of the touch panel 2 (FIG. 3), Newton ring prevention on the back side of the touch panel 2. Examples of the film include a structure (FIG. 4) in which the display element front film 1 of the present invention is laminated. Moreover, the structure which uses the film for display element front surface of this invention itself as a member of the outermost surface of a touchscreen as an anti-glare film is also mention | raise | lifted. Moreover, the structure which uses the film for display element front surface itself of this invention as a member of the outermost surface of a touch panel, an intermediate | middle, and a back surface as a Newton ring prevention film is also mentioned.

  Moreover, when a surface member is the polarizing film 2, the structure (FIG. 3) etc. which bonded the film for display element front surfaces of this invention as an anti-glare film on the surface side of the polarizing film 2 are mention | raise | lifted.

  The display element with a surface member of the present invention as described above can prevent sparkle while having predetermined functions (such as antiglare property and Newton's ring prevention property).

  Hereinafter, the present invention will be described in more detail with examples that further embody the embodiment of the present invention. In this example, “parts” and “%” are based on weight unless otherwise specified.

[Example 1]
On one side of a 125 μm thick transparent polyester film (Cosmo Shine A4350: Toyobo Co., Ltd.), a Newton ring prevention layer coating solution a having the following formulation is applied, dried and irradiated with ultraviolet rays to form a 3 μm thick Newton ring prevention layer. And the film for display element front surfaces of Example 1 was obtained.

<Newton ring prevention layer coating solution a>
・ 125 parts of ionizing radiation curable resin (Unidic 17-813: DIC, solid content 80%)
-Thermoplastic acrylic resin (Acridic A195: DIC, solid content 40%) 107 parts (glass transition temperature: 94 ° C., weight average molecular weight: 85000)
・ Photopolymerization initiator 3 parts (Irgacure 184: Ciba Japan)
-0.7 parts of acrylic resin particles (MX-500: Soken Chemical Industry Co., Ltd.)
(Average particle size: 5 μm, coefficient of variation: 9%)
・ 200 parts of diluted solvent

[Example 2]
A display element front film of Example 2 was obtained in the same manner as in Example 1 except that the amount of the thermoplastic acrylic resin added to the Newton ring prevention layer coating solution a was changed to 65 parts.

[Example 3]
A display element front film of Example 3 was obtained in the same manner as in Example 1 except that the amount of the thermoplastic acrylic resin added to the Newton's ring prevention layer coating solution a was changed to 250 parts.

[Example 4]
The display element front film of Example 4 was obtained in the same manner as Example 1 except that the thermoplastic acrylic resin of Newton's ring prevention layer coating solution a was changed to the following material and the addition amount was changed to 95 parts. .
-Thermoplastic acrylic resin (Acridic A166: DIC, solid content 45%)
(Glass transition temperature: 49 ° C., weight average molecular weight: 75000)

[Example 5]
A display element front film of Example 5 was obtained in the same manner as in Example 1 except that the acrylic resin particles of the Newton ring prevention layer coating solution a were changed to the following materials.
・ Acrylic resin particles (Techpolymer SSX-105: Sekisui Plastics Co., Ltd.)
(Average particle size: 5.3 μm, coefficient of variation: 8.5%)

[Example 6]
A display element front film of Example 6 was obtained in the same manner as in Example 1 except that the thermoplastic acrylic resin of the Newton ring prevention layer coating solution a was changed to the following material.
-Thermoplastic acrylic resin (Acridick WDL-787: DIC, solid content 40%)
(Glass transition temperature: 90 ° C., weight average molecular weight: 72000)

[Comparative Example 1]
The display element front film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the thermoplastic acrylic resin of Newton's ring prevention layer coating solution a was changed to the following material and the addition amount was changed to 85 parts. .
・ Thermoplastic acrylic resin (Acridic 49-394-IM: DIC, solid content 50%)
(Glass transition temperature: 16 ° C., weight average molecular weight: 65000)

[Comparative Example 2]
The display element front film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the thermoplastic acrylic resin of Newton's ring prevention layer coating solution a was changed to the following material and the addition amount was changed to 95 parts. .
・ Thermoplastic acrylic resin (Acridic A165: DIC, solid content 45%)
(Glass transition temperature: 66 ° C., weight average molecular weight: 42000)

[Comparative Example 3]
A display front film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the amount of the thermoplastic acrylic resin added to the Newton ring prevention layer coating solution a was changed to 40 parts.

[Comparative Example 4]
A display front film of Comparative Example 4 was obtained in the same manner as in Example 1 except that the amount of the thermoplastic acrylic resin added to the Newton ring prevention layer coating solution a was changed to 300 parts.

[Comparative Example 5]
A display element front surface film of Comparative Example 5 was obtained in the same manner as in Example 1 except that the acrylic resin particles of Newton's ring prevention layer coating solution a were changed to the following materials.
・ Acrylic resin particles (Techpolymer MB20X-5: Sekisui Plastics Co., Ltd.)
(Average particle size: 5 μm, coefficient of variation: about 20%)

[Evaluation]
The following evaluation was performed about the film for display element front surfaces obtained by Examples 1-6 and Comparative Examples 1-6. The results are shown in Table 1.

1. The liquid crystal display screen of a wide VGA liquid crystal having a sparkle size of 3 inches and a resolution of 480 × 854 dpi was displayed in green on the entire surface, and each display element front film was placed on the display element and visually observed. As a result, “◎” indicates that no sparkle is visible, “◯” indicates that the sparkle is slightly visible but does not hinder, and “×” indicates that the sparkle appears intense.

2. Newton's ring prevention property Each display element front film was placed on a glass plate having a smooth surface so that the Newton's ring prevention layer was in close contact with it and pressed with a finger, and whether or not Newton's ring occurred was visually evaluated. In the evaluation, “○” indicates that no Newton ring was generated, and “×” indicates that a Newton ring was generated.

3. Surface hardness Under the three-wavelength fluorescent lamp lamp, place the film for each display element on the black base so that the Newton ring prevention layer is on the top, and rub # 0000 steel wool with a load of about 2cm2 / 200g once, The flaws were visually evaluated. As a result, “◯” indicates that the scratches are hardly visible, “Δ” indicates that the scratches are slightly visible, and “X” indicates that the scratches are clearly visible.

  As is apparent from the results in Table 1, the films for the front surfaces of the display elements of Examples 1 to 6 are the ionizing radiation curable resin, the glass transition temperature of 45 ° C. or more, and the weight average molecular weight of 70,000 as the binder component of the functional layer. The above thermoplastic resin and / or thermosetting resin is included within the scope of the present invention, and the coefficient of variation in the particle size distribution of the matting agent in the functional layer is 15% or less, so that it is excellent in sparkle prevention. It was a thing.

  In particular, the films for the display element front surfaces of Examples 1, 3, 5, and 6 have an optimum ratio of the ionizing radiation curable resin and the thermoplastic resin and / or the thermosetting resin, and the thermoplastic resin and Since the glass transition temperature of the thermosetting resin is high, the sparkle prevention property is extremely excellent.

  On the other hand, in Comparative Examples 1 and 2, the weight ratio of the ionizing radiation curable resin to the thermoplastic resin and / or the thermosetting resin is within the range of the present invention, but the thermoplastic resin and / or the thermosetting resin. Type resin has a low glass transition temperature or a low weight average molecular weight. Therefore, sparkle could not be prevented.

  In Comparative Examples 3 and 4, the glass transition temperature and weight average molecular weight of the thermoplastic resin and / or thermosetting resin are within the scope of the present invention, but the weight ratio of the resin to the ionizing radiation curable resin is It is outside the scope of the present invention. Therefore, sparkle cannot be prevented or the hardness is extremely inferior.

  In Comparative Example 5, the glass transition temperature and the weight average molecular weight of the thermoplastic resin and / or thermosetting resin are within the scope of the present invention, and the weight ratio of the resin to the ionizing radiation curable resin is also the present invention. However, the coefficient of variation of the particle distribution of the matting agent in the functional layer exceeds 15%. Therefore, the sparkle cannot be prevented.

DESCRIPTION OF SYMBOLS 1 ... Display element front film 11 ... Transparent base material 12 ... Functional layer 121 ... Binder component 122 ... Matting agent 2 ... Protection plate, touch panel, polarizing plate 3, ... Display element 4... Display element with surface member

Claims (4)

  It has a functional layer on a transparent substrate, and the functional layer includes a binder component and a matting agent. The binder component includes an ionizing radiation curable resin, a glass transition temperature of 45 ° C. or higher, and a weight average molecular weight of 70,000 or higher. And the weight ratio of each component in the binder component is such that the ionizing radiation curable resin is 50% by weight or more and less than 85% by weight, and the thermoplastic resin and / or Alternatively, the weight ratio of the thermosetting resin is more than 15% by weight and 50% by weight or less, and the matting agent has a particle diameter distribution variation coefficient of 15% or less.   The film for front face of a display element according to claim 1, wherein the average particle diameter of the matting agent is 0.5 to 10 μm.   The display element front film according to claim 1, wherein the functional layer is an antiglare layer or a Newton ring prevention layer.   A display element with a surface member comprising a surface member on the display element, wherein the film for a display element front surface according to any one of claims 1 to 3 is included in at least a part of the surface member.

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