JP5016794B2 - Antireflection film - Google Patents

Description

The present invention relates to antireflective fill beam and a manufacturing method thereof used in the surface of the display such as LCD or PDP.

An antireflection film is generally provided on the surface of a display such as an LCD or PDP. As an antireflection film, a film prepared by forming a hard coat layer on the surface of a base film and laminating a single layer or a plurality of layers of an antireflection layer with an adjusted refractive index on the surface of the hard coat layer is known. ing.
Antireflection films are mostly used on the outermost surface of displays, and one of the required performances is that they are excellent in scratch resistance so that they are not damaged when the surface is wiped and cleaned. As a method for improving the scratch resistance of the surface, it is common to increase the surface hardness of the outermost layer. However, since the coating agent used is restricted in order to increase the surface hardness of the outermost layer, it has been difficult to produce an antireflection film that sufficiently satisfies other required performance.

On the other hand, it has been proposed to improve the scratch resistance by improving the adhesion between the outermost layer and the layer immediately below. As a method for improving the adhesion, when the lower layer is in a semi-cured state, the outermost layer coating agent is applied, and the outermost layer and the lower layer are mixed between the layers (see Patent Document 1), There is a method of improving adhesion by corona discharge treatment (see Patent Document 2).
In addition, it is not a method for improving the scratch resistance, but for the purpose of improving the adhesion between the transparent substrate film and the hard coat, a solvent that dissolves the substrate in the hard coat coating agent is used. It has been proposed to use (see Patent Document 3).

However, when the lower layer is semi-cured and the upper layer coating agent is applied, or when the coating is performed using a solvent that dissolves the underlying film, the lower resin component and the upper resin component Therefore, it is difficult to control the film thickness because it is necessary to control the film thickness in consideration of the degree of mixing. Further, if the surface treatment such as corona discharge treatment is performed to improve the adhesion, there is a problem that an apparatus is required for performing the surface treatment and costs are increased as the number of treatment steps increases. .
Japanese Patent Laid-Open No. 6-18704 JP 2003-294907 A Japanese Patent Laid-Open No. 6-16851

Accordingly, an object of the present invention is to provide an antireflection film that has no difficulty in controlling the film thickness and that has excellent scratch resistance even without a new treatment such as a surface treatment. . Another object is to provide a method for producing the antireflection film.

The present invention relates to antireflective fill beam and a manufacturing method thereof is shown below.
That, is formed below the cured state having a crosslinked structure on the transparent substrate film, anti-reflection film having the outermost layer is formed further coating material on the lower layer is cured coating, the top The SP value of the solvent used for the coating agent for the outer layer is −1 or more and +1 or less with respect to the SP value (cured state) of the resin component forming the lower layer matrix.
The resin forming the lower layer matrix is an ultraviolet curable resin, and the lower layer is irradiated with ultraviolet rays. The solvent contains a ketone solvent and an alcohol solvent, and the total amount of the ketone solvent and the alcohol solvent is 80% by weight or more of the total solvent.
Further, a coating agent containing an ultraviolet curable resin and a photopolymerization initiator is applied onto the base film directly or via another layer, and after irradiating ultraviolet rays to form a lower layer, The method for producing an antireflection film in which a coating agent to be the outermost layer is applied to the SP component of the resin component that forms the matrix of the lower layer is the SP value of the solvent used for the outermost layer coating agent ( It is characterized by being −1 or more and +1 or less with respect to (cured state).

  In the present invention, when the outermost layer is formed by coating the coating agent on the cured lower layer formed on the base film, a specific solvent is used as the coating agent for the outermost layer. By doing so, there is no difficulty in controlling the film thickness, and an antireflection film excellent in scratch resistance can be obtained without performing a new treatment such as a surface treatment.

  The antireflection film of the present invention has a lower layer formed on a transparent substrate film and an outermost layer formed on the lower layer. Specific configurations of the antireflection film include “transparent substrate film / hard coat layer / low refractive index layer” (configuration 1), “transparent substrate film / hard coat layer / high refractive index layer / low refractive index layer”. (Constitution 2), “Transparent substrate film / Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layer” (Constitution 3), etc. In the configuration 1, the hard coat layer is formed, and in the configurations 2 and 3, the high refractive index layer is formed at a position in contact with the low refractive index layer. However, the laminated structure of the antireflection film in the present invention is not particularly limited to those described above.

Below, the case of the structure 2 used as "a transparent base film / hard coat layer / high refractive index layer / low refractive index layer" is demonstrated as an example of the antireflection film concerning this invention.
In the reflective film of this embodiment, the coating material for the hard coat layer, the coating agent for the high refractive index layer, and the coating agent for the low refractive index layer that is the outermost layer are arranged in this order on the transparent base film surface. It is manufactured by coating, especially after the coating agent for the high refractive index layer is cured after coating (not in a semi-cured state) and then the low refractive index layer is coated and cured. It is.

  The transparent substrate film of the present invention may be any film as long as it is a transparent film. As the coating agent for the hard coat layer, a resin component and inorganic fine particles as required are mixed and appropriately dissolved in a solvent. An acrylic ultraviolet curable resin is preferable as the resin component. Examples of acrylic UV curable resins include polyester acrylate, urethane acrylate, polyether acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, 1,4-butanediol (meth) acrylate, and 1,6-hexadiol (meth) acrylate. , Neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, 3-methylpentanediol di (Meth) acrylate, diethylene glycol bis β- (meth) acryloyloxypropinate, trimethylolethane tri (meth) acrylate, Methylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (2-hydroxyethyl) isocyanate di (meth) acrylate, pentaerythritol tetra (meth) acrylate, 2,3 -Bis (meth) acryloyloxylethyloxymethyl [2.2.1] heptane, 1,2-bis (meth) acryloyloxymethylhexane, nonaethylene glycol di (meth) acrylate, tetradecane ethylene glycol di (meth) acrylate, Polyfunctional (meth) acrylic acid esters such as 10-decanediol (meth) acrylate, acrylic acid esters such as N-vinylpyrrolidone, ethyl acrylate and propyl acrylate, ethyl meta Relate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate, isooctyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, (meth) acrylic acid esters such as nonylphenyl methacrylate. Further, it is preferable to adjust the hardness and refractive index by appropriately blending inorganic fine particles, conductive fine particles, a photoinitiator, a dispersant and the like.

As the coating agent for the high refractive index layer, similarly to the coating agent for the hard coat layer, an acrylic ultraviolet curable resin and inorganic fine particles for adjusting the refractive index were appropriately dissolved or dispersed in a solvent. Use things. Examples of the inorganic fine particles for adjusting the refractive index include ZrO ₂ , TiO ₂ , ZnS, CeO ₂ , SiO ₂ , Ti ₂ O ₃ , Ti ₂ O ₅ , ZnO, or conductive ITO (tin-containing indium oxide) or ATO. Examples thereof include metal oxide fine particles such as (antimony-containing tin oxide) and Sb ₂ O ₅ .

As for the coating agent for the low refractive index layer which is the outermost layer, the acrylic UV curable resin and the refractive index are adjusted similarly to the coating agent for the hard coating layer and the high refractive index layer. Inorganic fine particles dissolved or dispersed in a solvent are used. In particular, those using acrylic ultraviolet curable resins containing fluorine atoms as the resin component, and SiO ₂ , hollow to lower the refractive index. It is preferable to use a mixture of inorganic fine particles such as silica and magnesium fluoride.

In the present invention, the SP value (cured state) of the resin component that forms the matrix of the high refractive index layer (lower layer) as the solvent used in the coating agent of the low refractive index layer that is the outermost layer. However, it is characterized by using one that is -1 or more and +1 or less. In the case of a mixed solvent, the SP value of the solvent in the present invention means not the SP value of a single solvent but the SP value of the mixed solvent. Accordingly, it is possible to mix solvents having different SP values so that the SP value falls within the above range, and an antireflection film having excellent scratch resistance can be produced.
In general, the SP value is an index indicating the polarity of a substance, and it is said that the solubility is better as the SP value of the solvent is similar to the SP value of the solute.
When the difference between the SP value of the solvent used in the coating agent for the low refractive index layer and the SP value of the resin component forming the matrix in the cured state of the high refractive index layer formed immediately below is greater than 1, Is lowered, and the surface of the antireflection film is easily damaged.

The solvent of the coating agent for the low refractive index layer is selected so that the coating film has an efficient and uniform film thickness by controlling the evaporation rate and the coating film viscosity in addition to the SP value. Usually, a low boiling point solvent having a boiling point of 100 ° C. or less and a high boiling point solvent having a boiling point of 100 ° C. or more are often mixed at an appropriate ratio.
Solvents used include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alcohol solvents such as methanol, ethanol, normal propanol, isopropanol, normal butanol and isobutanol, hexane, cyclohexane, methylcyclohexane and ethyl. Examples include cyclohexane, benzene, toluene, xylene, styrene, ethyl acetate, butyl acetate, and ethyl lactate. Among these, ketone solvents and alcohol solvents are preferable, and it is particularly preferable that the total amount of the ketone solvent and the alcohol solvent is 80% by weight or more of the total solvent.

  In the present invention, the coating agent for the low refractive index layer, which is the outermost layer, is applied after the lower layer is cured, and the solvent is considered to volatilize in a short time after coating. Represents solubility, but the solvent for the outermost layer in the present invention dissolves or swells the lower high refractive index layer (it is considered to have a crosslinked structure because it is cured). Unthinkable. Therefore, although it is not clear why the scratch resistance is improved by adopting the configuration of the present invention, the SP value of the solvent of the outermost layer coating agent and the SP value of the resin component in the cured state of the lower layer are made similar. Therefore, the affinity between the lower layer and the outermost layer is improved, and it is considered that an antireflection film having improved adhesion and excellent scratch resistance is formed.

  In the above description, the case of the above-described configuration 2 (“transparent substrate film / hard coat layer / high refractive index layer / low refractive index layer”) has been described. An antireflection film having excellent scratch resistance can be obtained by adjusting the solvent of the coating agent. That is, in the case of the configuration 1 in which the low refractive index layer (outermost layer) is formed on the hard coat layer, the solvent of the coating agent for the low refractive index layer is used as the SP of the resin component that forms the matrix in the cured state of the hard coat layer. By using a film whose value is adjusted to −1 or more and +1 or less, an antireflection film having excellent scratch resistance can be produced.

(1) Formation of hard coat layer The transparent substrate film used was a triacetyl cellulose film having a thickness of 80 μm.
The coating agent for the hard coat layer comprises 685 parts by weight of a mixture of 300 parts by weight of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, 9.0 parts by weight of a photopolymerization initiator, and 6.0 parts by weight of a photosensitizer. Dissolved in a mixed solvent of parts by weight of isopropyl alcohol / ethanol = 70/30% by weight.
The hard coat layer coating agent was applied to the surface of the transparent substrate film using a gravure coater, dried at 80 ° C., and then irradiated with ultraviolet rays to form a 6 μm thick hard coat layer.

(2) Formation of Medium Refractive Index Layer The coating agent for the medium refractive index layer is prepared by dispersing 230 parts by weight of ITO fine particles, 30 parts by weight of a dispersant, and 670 parts by weight of isopropyl alcohol with a dynomill, and removing coarse particles with a centrifuge. Removal, to obtain a dispersion having an average particle diameter of 50 nm, to which 107.5 parts by weight of urethane acrylate, 37.5 parts by weight of dipentaerythritol hexaacrylate and 3.8 parts by weight of a photopolymerization initiator were added, and isopropyl alcohol / ethanol = 70 The concentration is 5% by weight with a / 30% by weight mixed solvent.
This medium refractive index layer coating solution was applied onto the hard coat layer using a gravure coater, dried at 80 ° C., and then irradiated with ultraviolet rays to form a medium refractive index layer of 75 nm.

(3) Formation of High Refractive Index Layer The coating agent for the high refractive index layer is prepared by dispersing 250 parts by weight of titanium oxide, 50 parts by weight of a dispersant, and 700 parts by weight of isopropyl alcohol with a dynomill, and removing coarse particles with a centrifuge. Removal, a dispersion having an average particle size of 40 nm was added, and 32.5 parts by weight of urethane acrylate, 30.0 parts by weight of dipentaerythritol hexaacrylate and 3.2 parts by weight of a photopolymerization initiator were added thereto, and isopropyl alcohol / ethanol = 70 The concentration is adjusted to 5% by weight with a / 30% by weight mixed solvent.
The coating agent for the high refractive index layer was coated on the middle refractive index layer using a gravure coater, dried at 80 ° C., and then irradiated with ultraviolet rays to form a high refractive index layer having a thickness of 95 nm. The SP value of the resin component of the cured high refractive index layer is 10.6.

(4) Adjustment of coating agent for low refractive index layer The coating agent for the low refractive index layer comprises 45 parts by weight of a fluorine-containing copolymer, 25 parts by weight of dipentaerythritol hexaacrylate, 25 parts by weight of silica fine particles, and The solvent shown in Examples 1 to 6 and Comparative Examples 1 to 3 in Table 1 below was added to 5 parts by weight of the photopolymerization initiator for dilution, and the concentration of the low refractive index layer forming component was 4% by weight, and the solvent was 96% by weight. % Coating agent was adjusted.

(5) Formation of outermost layer The low refractive index coating agent prepared in (4) above is applied on the high refractive index layer using a microgravure, dried at 80 ° C., and then irradiated with ultraviolet rays. Then, an outermost layer having a thickness of 100 nm was formed to produce an antireflection film.

(6) Scratch resistance test The scratch resistance test was conducted using a reciprocating wear tester “HEIDON Tripogear TYPE: 30” manufactured by Shinto Kagaku Co., Ltd. On the surface of the antireflection film was fixed to the stage, carried out by 10 reciprocating in the direction of rubbing the surface abrasion head fitted with Bemcot (M-3) a load 250 gf / cm ^2, in a state pressed against a load 500 gf / cm ² Evaluation was performed by the number of scratches formed on the surface of the antireflection film after 10 reciprocations. The results are shown in Table 2 below.

As shown in Table 2, the SP value of the solvent used for the coating agent for the outermost layer is plus or minus from the SP value (10.6) of the resin (cured state) used for the high refractive index layer (intermediate layer). when using the 1 within the is coating agents of examples 1 to 5, the same despite the resin is a composition, when the load of the BEMCOT of 250 gf / load even for cm ² 500gf / cm ² Even so, it can be seen that it is less likely to be damaged than Comparative Examples 1 to 3, which are SP values that are one or more away from 10.6.

Claims (4)

Has a crosslinked structure on the transparent substrate film is formed with a lower layer of hardening an unswollen state or dissolved, is the outermost layer is formed by further curing the coating applied agent onto the lower layer reflection In the prevention film,
The SP value of the solvent used for the coating agent of the outermost layer is -1 or more and +1 or less with respect to the SP value (cured state) of the resin component forming the lower layer matrix. .   2. The antireflection film according to claim 1, wherein the resin forming the matrix of the lower layer is an ultraviolet curable resin, and the lower layer is irradiated with ultraviolet rays.   3. The antireflection film according to claim 1, wherein the solvent contains a ketone solvent and an alcohol solvent, and the total amount of the ketone solvent and the alcohol solvent is 80% by weight or more of the total solvent. On a substrate film, directly or via another layer, and applying a coating agent containing a UV-curable resin and a photopolymerization initiator, after forming a lower layer having a crosslinked structure by irradiation with ultraviolet light , on the lower layer, the method of manufacturing the anti-reflection film for applying a coating agent comprising the outermost layer without swelling or dissolving the lower layer,
The SP value of the solvent used for the coating agent of the outermost layer is -1 or more and +1 or less with respect to the SP value (cured state) of the resin component forming the lower layer matrix. Manufacturing method.