JP2009003351A - Coating composition and antireflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition and an antireflection film capable of reducing occurrence of peeling of a hard coat layer. <P>SOLUTION: The coating composition for forming the hard coat layer on a base film contains a reactive silicate having at least three functional groups. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating composition for a hard coat layer constituting an antireflection film and an antireflection film using the same. More specifically, a coating composition for a hard coat layer constituting an antireflection film applied to the display screen surface of a display (for example, CRT display, plasma display, liquid crystal display, projection display, EL display, etc.) and reflection using the same The present invention relates to a prevention film.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate (PET) and polyethylene naphthalate have excellent mechanical properties, heat resistance, chemical resistance, etc., so magnetic tape, ferromagnetic thin film tape, packaging film, It is widely used as a material for electronic component films, electrical insulating films, laminating films, films to be attached to the surface of displays, and protective films for various members. In particular, for display applications, base films such as prism lens sheets, touch panels, and backlights, which are members of liquid crystal display devices, antireflection films for televisions, antireflection films used for front optical filters for plasma televisions, Applications include infrared cut film and electromagnetic shielding film base film.

  Base films used for optical films such as antireflection films may require easy adhesion to other materials in addition to excellent transparency. That is, in order to secure the performance as an optical film or enhance the function, for example, a hard coat layer material for forming a hard coat layer provided for surface protection, an adhesive material, An antireflection treatment material and various other coating materials are applied, and excellent easy adhesion to such a coating material may be required.

  However, a normal polyester film has high crystallinity, and it has been generally difficult to ensure adhesion with the coating material and the like. Therefore, for example, in order to ensure easy adhesion with the hard coat layer, a method of forming an easy-adhesion film on the surface of the polyester film is a gas phase surface treatment method such as corona treatment or flame treatment, application of a primer or the like. A chemical surface treatment method using, for example, is used. In particular, since a PET film used for display applications is required to have high transparency and adhesion, it is common to use a type in which an easy-adhesion film having a film thickness of nanometer order is formed (for example, , See Patent Document 1).

  When using a polyester film on which such an easy-adhesion film is formed, as described above, high transparency and adhesion with the hard coat layer can be ensured, and the blocking resistance of the polyester film can be improved. it can. However, when used for an optical film such as an antireflection film, when a hard coat layer material or the like is coated on it due to factors such as a mismatch in refractive index between the easy-adhesive film and the polyester film, and variations in the film thickness of the easy-adhesive film. This was a cause of optical interference unevenness. Moreover, due to the above-mentioned refractive index mismatch, the reflection interface is increased, resulting in a problem of increased reflectance.

Then, although using the polyester film which does not have an easily bonding film | membrane is also considered, peeling of a hard-coat layer is anxious about this case.
Japanese Patent Laid-Open No. 9-220791

  The present invention has been made in view of the above points, and an object of the present invention is to provide a coating composition capable of reducing the occurrence of peeling of a hard coat layer and an antireflection film in which the coating composition is reduced. is there.

  As a result of intensive studies on the above problems, the present inventors have a plurality of functional groups, particularly three or more functional groups, when a hard coat layer is formed (or coated) on a base film as a substrate. If a coating paint containing a silicate (ie reactive silicate) is used, the surface of the coating layer formed thereby (also referred to as a “hard coat layer” as conventionally called in the art) is more Many functional groups exist, and it discovered that the adhesiveness of a base film and a hard-coat layer and the adhesiveness of a hard-coat layer and an antireflection layer could be improved, and came to complete this invention.

  Accordingly, the present invention provides a coating composition used for forming a hard coat layer on a base film, comprising a silicate having at least three functional groups as a reactive silicate. Exist. By adopting such a configuration, the adhesion between the hard coat layer and the base film and / or the adhesion between the hard coat layer and the antireflection layer is improved, and the peeling between the base film and the antireflection layer is reduced. can do.

  According to the present invention, the coating composition has many functional groups, particularly three or more functional groups, and more functional groups are present on the surface of the hard coat layer formed thereby. The coating layer formed by use can more sufficiently ensure the adhesion between the base film and the hard coat layer and / or the adhesion between the hard coat layer and the antireflection layer. By using such an antireflection film, it is possible to prevent reflection of light on a display surface of an image display device or the like and to suppress peeling of the antireflection layer from the display surface.

  Hereinafter, an antireflection film according to the present invention and a coating composition used as a precursor for forming a hard coat layer will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an example of the antireflection film of the present invention. As shown in the figure, a hard coat layer 2 is formed on at least one surface (for example, the upper surface as shown in the figure) of a transparent substrate, for example, using the coating composition of the present invention. This is an antireflection film when the antireflection layer 3 is formed. Moreover, you may further provide the antifouling layer 4 on the surface of the antireflection layer 3 as needed.

  In the present invention, the hard coat layer 2 is constituted by a coating composition having a reactive silicate having three or more functional groups, and the reactive silicate is based on the total weight of the coating composition. Preferably it is 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, particularly preferably 1 to 10% by weight. A large number of functional groups exist on the surface of the hard coat layer formed by the coating composition, and the bondability with other layers is enhanced by the functional groups. Therefore, the adhesion between the base film and the hard coat layer and / or the adhesion between the hard coat layer and the antireflection layer is improved.

  The coating composition of the present invention for forming such a hard coat layer 2 is formed, for example, by dispersing reactive silicate in an ultraviolet curable resin and curing it by ultraviolet irradiation. The reactive silicate is optionally hydrolyzed and then condensed with each other to form a crosslinked structure, or in addition to such condensation reaction, reacts with the hydrolyzed reactive silicate contained in the coating composition. It reacts with other components having possible functional groups, and as a result, forms a hard coat layer in which a part of the functional groups of the reactive silicate is present on the surface. For example, it is considered that at least a part of the reactive silicate is present in a cured resin in a state where a crosslinked structure is formed.

The reactive silicate according to the present invention will be described in more detail. The reactive silicate has a basic skeleton of at least (SiO ₂ ) _m (m is a positive integer, preferably 1 to 50, more preferably 1 to 30), and has a silanol group and / or an alkoxy group. It is a silicate compound having at least three functional groups per molecule. This silicate compound may contain a bond represented by Si—R ¹ (R ¹ is a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms or a phenyl group) in the molecule. This silicate compound has a property that an alkoxy group (when present) has a strong tendency to be hydrolyzed by moisture present around it to form a silanol group and stabilize it.

  Although it does not specifically limit as said silicate compound, For example, what hydrolyzes the same or different alkoxysilane which has a structure shown to the following general formula (I), and is obtained by polycondensation etc. are mentioned. However, the obtained silicate compound has at least three alkoxy groups and / or silanol groups.

SiR ¹ _n (OR ² ) _4-n (I)
[R ¹ and R ² in formula (I) are each a substituted or unsubstituted alkyl group or phenyl group having 1 to 5 carbon atoms, may be the same or different from each other, R ¹ or R ² is more When they are present, they may be the same as or different from each other, and n is an integer of 0 to 2. ]

  More specifically, as the alkoxysilane represented by the general formula (I), a trifunctional alkoxysilane represented by the following general formula (II) and a tetrafunctional alkoxysilane represented by the following general formula (III) Etc. For example, a reactive silicate can be obtained by hydrolysis and condensation using at least one of these.

R ³ —Si (OR ⁴ ) ₃ (II)
[R ³ and R ^{4 in} Formula (II) are a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms or a phenyl group, and may be the same or different from each other. Three R < ⁴ > may mutually be same or different. ]

Si (OR ⁵ ) ₄ (III)
[In Formula (III), R ⁵ represents a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms or a phenyl group. Four R < ⁵ > may mutually be same or different. ]

  The trifunctional and tetrafunctional alkoxysilanes represented by the above formulas (II) and (III) are not particularly limited, but specific examples thereof include, for example, methyltrimethoxysilane. Methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane and the like are used. As the tetrafunctional alkoxysilane, for example, tetramethoxysilane, tetraethoxysilane, or the like is used.

  As the base film 1 to which the coating composition of the present invention is applied, a polyester film is preferably used. Examples of such polyester include aromatic dicarboxylic acid components such as terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and 4,4′-diphenyldicarboxylic acid, and ethylene glycol and 1,4-butanediol. An aromatic polyester composed of glycol components such as 1,4-cyclohexanedimethanol and 1,6-hexanediol is preferred, and polyethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate are particularly preferred. Further, it may be a copolyester such as a plurality of exemplified components.

  In order to improve the roll-up property of the film during film formation and the transportability of the film when forming the hard coat layer 2 or the pressure-sensitive adhesive, the polyester film 1 is organic as a lubricant as necessary. Alternatively, inorganic fine particles can be contained. Examples of such fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin fine particles, crosslinked polystyrene resin fine particles, urea resin fine particles, melamine resin fine particles, and crosslinked silicone resin fine particles. In addition to the fine particles, a colorant, an antistatic agent, an ultraviolet absorber, an antioxidant, a lubricant, a catalyst, other resins, and the like can be optionally contained as long as the transparency is not impaired.

  The polyester film 1 as described above has a haze of 3% or less, preferably 1.5% or less. If the haze exceeds 3%, the visibility may be impaired in various display applications, which may not be suitable for optical applications. From this viewpoint, in order to improve blocking resistance in a roll state, slipperiness, and adhesion to the hard coat layer 2 while maintaining high transparency with a haze of 3% or less, easy adhesion on the nanometer order Conventionally, a polyester film coated with a film is generally used.

  However, when a polyester film coated with such an easy-adhesion film, such as a PET film, is used, the refractive index of the easy-adhesion film is generally different from the refractive index of the polyester of the base film. When the difference in refractive index between the easy-adhesive film and the hard coat layer is large, when the hard coat layer 2 is coated, unevenness in appearance interference occurs due to the film thickness unevenness of the easy-adhesive film and the hard coat layer 2. There was a problem. When a hard coat layer having a refractive index of 1.58 to 1.85 is provided on a PET film with an easy adhesive layer, optically, the interface between the hard coat layer / the easy adhesive layer and the easy adhesive layer / PET Causes reflection, and deteriorates the reflectance characteristics and interference unevenness characteristics of the antireflection film. In order to suppress this reflection, it is necessary to suppress the optical adverse effect caused by the easily adhesive layer.

  The reflectance of the PET film with the easy adhesion layer decreases as the refractive index of the easy adhesion layer used decreases from the PET film (n = 1.69) and the film thickness of the easy adhesion layer approaches 100 nm. Conversely, when the optical adverse effect of the easy-adhesion layer is suppressed, the reflectance approaches 6.5% of PET alone. In the present invention, in view of this, as the polyester film to be used, it is preferable to use a film having a reflectance of 4% or more of a polyester film having an easy adhesion layer on the side in contact with the hard coat layer. Adverse effects can be suppressed.

  In order to increase the reflectance of the PET film with an easy adhesion layer, it is preferable to control the film thickness of the easy adhesion layer to 5 nm or more and 80 nm or less. When the thickness is 5 nm or less, the easy-adhesive material cannot be uniformly coated on the PET film, and it becomes difficult to ensure stable adhesion between the PET and the hard coat layer. When the thickness is 80 nm or more, reflection on the easy-adhesion layer increases, and problems such as an increase in reflectivity as an antireflection film and deterioration in interference unevenness occur. In order to increase the reflectance of PET with an easy adhesion layer, the refractive index of the easy adhesion layer is preferably 1.55 to 1.75. If it is 1.58 or less or 1.75 or more, the difference between the refractive index of the hard coat material and PET becomes large, and problems such as an increase in reflectance as an antireflection film and deterioration in interference unevenness occur.

  Moreover, the thickness of the polyester film 1 used by this invention is although it does not specifically limit, 50-200 micrometers is preferable.

  The hard coat layer 2 improves the hardness of the surface of the base film as a transparent plastic substrate, prevents scratches caused by scratching with a load such as a pencil, and suppresses the occurrence of cracks in the antireflection layer due to bending of the transparent base film The mechanical strength of the antireflection film can be improved. In this sense, it is called a hard coat layer.

  In order to improve the hardness of the hard coat layer, the coating composition of the present invention preferably contains a reactive curable resin, that is, a thermosetting resin and / or an ionizing radiation curable resin. As the thermosetting resin, phenol resin, urea resin, diallyl phthalate resin, melamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, amino alkyd resin, silicon resin, polysiloxane resin, or the like is used. A crosslinking agent, a polymerization initiator, a curing agent, a curing accelerator, and a solvent are added to these resins as necessary.

  The ionizing radiation curable resin preferably has an acrylate functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin. , Polythiol polyene resins, oligomers of polyfunctional compounds such as polyhydric alcohols, prepolymers, and reactive diluents such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N- Monofunctional monomers such as vinylpyrrolidone, as well as polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene Examples include recall di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate and the like. These coating compositions can contain a relatively large amount of these.

  Further, in order to use the ionizing radiation curable resin as an ultraviolet curable resin, the coating composition of the present invention preferably contains a photopolymerization initiator therein. Examples of the photopolymerization initiator include acetophenones, benzophenones, α-amyloxime esters, and thioxanthones. A photosensitizer may be used in addition to the photopolymerization initiator. Examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, and thioxanthone.

  The coating composition of the present invention is preferably cured after application and drying of the coating composition, for example, by ultraviolet irradiation or heating.

  The refractive index of the hard coat layer formed by the coating composition of the present invention is preferably close to the refractive index of the base film. Moreover, although sufficient intensity | strength will be acquired if the film thickness of a hard-coat layer is 1-2 micrometers or more, the range of 1-10 micrometers is preferable from a viewpoint of the transparency of the film, the coating accuracy, and the curl property of the base film by stress.

  In applying the coating composition of the present invention, in order to ensure adhesion between the hard coat layer and the base film, for example, a polyester film, it is preferable to improve the adhesion by the surface treatment described above for the polyester film. In another embodiment, it is preferred to mix the non-reactive resin with the coating composition of the present invention in an amount up to 50% by weight in the total composition. If the amount of the non-reactive resin is too large, the hard property becomes insufficient. As the non-reactive resin, a thermoplastic resin is mainly used. Specifically, polymethyl methacrylate acrylate and polybutyl methacrylate can be used, ensuring adhesion and keeping the coating film high in hardness. Adhesion can be improved by either one or both of the surface treatment and the thermoplastic resin.

  The refractive index of the hard coat layer that can be formed using the coating composition of the present invention is usually about 1.49 to 1.52. In order to increase the refractive index of the hard coat layer, ultrafine particles such as high refractive index metals and metal oxides can be added to the coating composition of the present invention. In an antireflection film using a base film, for example, a polyester film, the preferred refractive index of the hard coat layer for lowering the reflectance is 1.6 to 2.0, and ultrafine particles are used to achieve such a refractive index. Can be used. As the material of the ultrafine particles having a high refractive index, at least one oxide of titanium, aluminum, cerium, yttrium, zirconium, niobium, and antimony can be used.

It is preferable to impart antistatic properties to the hard coat layer that can be formed using the coating composition of the present invention, and to impart antistatic properties and anti-dust adhesion properties as an antireflection film. In order to impart antistatic properties, it is preferable to add ultrafine particles such as conductive metals and metal oxides to the coating composition of the present invention. _{ITO, SnO 2, ATO, PTO} , it is preferable to add ultrafine particles such as _Sb 2 _{O 5.}

By using the high refractive index ultrafine particles and the conductive ultrafine particles as described above in combination without aggregation, a hard coat layer having a high refractive index and excellent antistatic properties can be obtained. In order to obtain antistatic properties, the sheet resistance of the hard coat layer is preferably 10 ¹³ Ω / □ or less.

  It is preferable to perform a surface treatment of the hard coat layer before applying the low refractive index coating agent on the hard coat layer formed by the coating composition of the present invention to form the antireflection layer. By performing the surface treatment, wettability and adhesion between the hard coat layer and the antireflection layer can be improved. As the surface treatment method, physical surface treatment such as plasma discharge treatment, corona treatment, flame treatment and chemical surface treatment with a coupling agent, acid, or alkali can be used.

  In the antireflection film of the present invention, the antireflection layer 4 preferably has a refractive index of 1.30 to 1.45, more preferably 1.30 to 1.40. The thickness (d) of the antireflection layer is preferably nd = λ / 4, where n is the refractive index of the antireflection layer. Specifically, the thickness is preferably 50 to 400 nm, and more preferably 50 to 200 nm.

  The binder material used for the low refractive index coating agent may be a silicon alkoxide type or a polymer (UV curable resin, thermosetting resin) having a saturated hydrocarbon or polyether as a main chain. Such a polymer is preferably formed using a monomer containing a fluorine atom.

  In order to reduce the refractive index of the antireflection layer, by adding fine particles of low refractive index (refractive index: 1.20 to 1.45) to the low refractive index coating agent containing the binder that forms the antireflection layer. realizable. The average particle diameter of the fine particles is preferably 0.5 to 200 nm. When the average particle size is larger than 200 nm, light is irregularly reflected by Rayleigh scattering in the obtained antireflection layer, and the antireflection layer looks whitish, and its transmittance may be lowered. If it is 0.5 nm or less, the dispersibility of the fine particles is lowered, and aggregation occurs in the coating liquid.

  Moreover, it is preferable that the addition amount of microparticles | fine-particles is 20-99 volume% on the basis of a low refractive index coating agent. If it is 20% by volume or less, the effect of lowering the refractive index is small, and the effect of lowering the refractive index is greater as the amount of fine particles added is larger.

  When the antireflection film of the present invention is disposed on the outermost surface of a display or the like, surface hardness and abrasion resistance that can withstand actual use are required. In such a case, high film hardness is required as an antireflection layer. However, in general, in a particle-filled composite material, the maximum volume fraction of fine particles when spherical particles having the same particle diameter (fully monodispersed) are closest packed is 0.74 according to the Horsfield packing model. Therefore, a 26 volume% interparticle gap is inevitably generated from the geometrical relationship. Therefore, ideally, when the low refractive index coating agent contains 26% by volume binder material (74% by volume fine particles), all the voids between the fine particles are replaced by the binder material, which is highly filled and very dense low refractive A thin film is obtained. However, in reality, the fine particles have a particle size distribution, and the wettability of the fine particle / binder interface is insufficient, and the nano-sized particle diameter causes aggregation in the low refractive index coating agent or in the drying process. Yes. Therefore, actually, in the region where the amount of fine particles added is 70% by volume or more, defective filling of the fine particles occurs in the antireflection layer, and voids due to unfilled binder material between the fine particles are generated.

  The binder unfilled portion in the antireflection layer generated in the fine particle highly filled region significantly reduces the strength and wear resistance of the thin film. Therefore, the method of reducing the refractive index of the antireflection layer by adding low refractive index fine particles is in a trade-off relationship with wear resistance in a high-filled region of fine particles of 70% by volume or more, and is difficult to use practically.

  The low refractive index fine particles desirably have a refractive index of 1.5 or less. Specifically, fluoride fine particles such as silica fine particles, hollow silica fine particles, magnesium fluoride, lithium fluoride, aluminum fluoride, calcium fluoride, and sodium fluoride are preferable. These fine particles are used alone or in combination. These fine particles are subjected to a surface treatment and dispersed in order to make the binder resin compatible.

In the following, an antireflection film according to the present invention was prepared, and a comparative example and a comparative experiment were performed.
(Preparation of base film)
First, a polyester (PET) film (side 10 cm, thickness 188 μm (manufactured by Toyobo Co., Ltd .: A4100)) was prepared as a base film. Subsequently, the surface of the PET film was subjected to corona treatment with a plasma screening apparatus (PX250) manufactured by Samco International.

ＭＳ５１（三菱化学株式会社製）

ＭＳ５６（三菱化学株式会社製）

(Preparation of coating composition)
Then, the coating composition of this invention was prepared using the following components as a material which forms the hard-coat layer formed on PET film after corona treatment.
・ Acrylic ultraviolet curable resin (Daiichi Seika Kogyo Co., Ltd. (Seika Beam PET-HC15, active ingredient 60%))
・ High refractive index nanoparticles: Titanium Co., Ltd. titanium oxide particles, 760T (dispersing solvent: toluene, solid content 48%)
Conductive nanoparticles: ATO particles manufactured by Catalyst Kasei Kogyo Co., Ltd., ELCOM P-specialized product A (dispersion solvent: MEK / toluene (4/1), solid content 30%)
・ Reactive silicate TSL8370 (manufactured by GE Toshiba Silicone Co., Ltd.)

MS51 (Mitsubishi Chemical Corporation)

MS56 (Mitsubishi Chemical Corporation)

This coating composition was applied onto a corona-treated PET film, dried at 80 ° C. for 1 minute, and then cured by irradiation with ultraviolet rays at an intensity of 600 mJ / cm ² . Thereby, a hard coat layer having a thickness of 3 μm was formed.

(Preparation of low refractive coating)
Subsequently, a low refractive coating agent to be applied to the hard coat layer was prepared. First, 356 parts of methanol was added to 208 parts by weight of tetraethoxysilane, and further 18 parts by weight of water and 18 parts by weight of 0.01N hydrochloric acid aqueous solution were added and mixed with a disper to obtain a mixed solution. This liquid mixture was stirred for 2 hours in a 25 ° C. constant temperature bath and used as a silicone resin (A) having a weight average molecular weight adjusted to 850.

  Next, hollow silica IPA (isopropanol) dispersion sol (Thruria CS-60IPA, solid content 20% by weight, manufactured by Catalyst Kasei Kogyo Co., Ltd.) is added to the silicone resin (A) as low refractive index fine particles. / The silicone resin was blended so as to have a predetermined volume ratio in terms of condensation solids, and then diluted with methanol so that the total solid content was 1%, thereby adjusting the low refractive coating agent. This mixed solution was applied to the hard coat layer with a wire bar coater # 10 so as to have a film thickness of 100 nm, and dried at 120 ° C. for 15 minutes to form an antireflection layer. This produced the anti-reflective film which concerns on an Example.

(Example 1)
A coating composition (30% by weight of UV curable resin, 30% by weight of titanium oxide particles 760T, 1% by weight of reactive silicate TSL8370, and 1% by weight of MS51) is coated on a corona-treated PET film. Coating was performed to obtain a cured film having a thickness of 3 μm.

  A low refractive index coating agent in which 60% by volume of CS-60IPA in a total amount was dispersed on the silicone resin (A) matrix was coated with a wire bar coater so as to have a film thickness of about 100 nm. This was cured at 120 ° C. for 15 minutes to produce an antireflection film.

(Example 2)
An antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1 except that TSL8370 was changed to 10% by weight and MS51 was changed to 10% by weight as the reactive silicate.

(Example 3)
An antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1 except that 1% by weight of TSL8370 and 1% by weight of MS56 were used as reactive silicates.

Example 4
An antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1 except that TSL8370 was changed to 10% by weight and MS56 was changed to 10% by weight as the reactive silicate.

(Example 5)
A coating composition (30% by weight of an ultraviolet curable resin, 30% by weight of titanium oxide particles 760T, 10% by weight of ATO particles, 1% by weight of reactive silicate TSL8370, and 1% by weight of MS51) was used. Except that, an antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1.

(Example 6)
A coating composition (30% by weight of UV curable resin, 30% by weight of titanium oxide particles 760T, 10% by weight of ATO particles, 10% by weight of reactive silicate TSL8370, and 10% by weight of MS51) was used. A PET film having an antireflection layer laminated thereon was produced in the same manner as in Example 1 except that.

(Example 7)
A coating composition (30% by weight of UV curable resin, 30% by weight of titanium oxide particles 760T, 10% by weight of ATO particles, 1% by weight of reactive silicate TSL8370, and 1% by weight of MS56) was used. Except that, an antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1.

(Example 8)
A coating composition (30% by weight of an ultraviolet curable resin, 30% by weight of titanium oxide particles 760T, 10% by weight of ATO particles, 10% by weight of reactive silicate TSL8370, and 10% by weight of MS56) was used. Except that, an antireflection film having an antireflection layer laminated thereon was produced in the same manner as in Example 1.

(Comparative Example 1)
An antireflection film in which a hard coat layer and an antireflection layer were laminated was prepared in the same manner as in Example 1 except that no reactive silicate was contained.

(Comparative Example 2)
An antireflection film in which a hard coat layer and an antireflection layer were laminated was prepared in the same manner as in Example 5 except that no reactive silicate was contained.

  Then, the evaluation result of the antireflection film of Examples 1-8 and Comparative Examples 1-2 is shown in Table 1. The reflectivity was measured by specular reflection at 5 degrees using a spectrophotometer U-4100 manufactured by Hitachi High-Technologies Co., Ltd., after blackening the back of the sample based on JIS R-3106.

  The adhesion (cross cut tape test) was measured by performing a cross-cut tape peeling test on the sample in accordance with JIS D0202-1988. For the cross-cut tape test, cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.) is used, and the film is peeled after being in close contact with the film of the finger. Judgment is represented by the number of squares that do not peel out of 100 squares, where 100/100 is the case where no peeling occurs, and 0/100 is the case where the peeling is complete.

  In the antireflection film (Examples 1 to 8) according to the present invention, it was confirmed that the adhesion was remarkably improved while having a low reflectance as compared with Comparative Examples 1 and 2.

FIG. 1 is a cross-sectional view showing an example of an antireflection film.

Explanation of symbols

1 Polyester film 2 Hard coat layer 3 Antireflection layer

Claims (7)

A coating composition for forming a hard coat layer on a base film,
A coating composition comprising a reactive silicate having at least three trifunctional groups.   The coating composition according to claim 1, wherein the reactive silicate has 3 functional groups.   The coating composition according to claim 1, wherein the reactive silicate has 4 functional groups.   2. A coating composition according to claim 1, comprising both a reactive silicate having three functional groups and a reactive silicate having four functional groups.   The coating composition according to claim 1, comprising a filler surface-treated with a reactive silicate.   The coating composition according to claim 5, wherein the filler contains at least one oxide of titanium, aluminum, cerium, yttrium, zirconium, niobium, antimony, indium, zinc, tin and silicon.   A base film, an easy-adhesion layer adhered on the base film, a hard coat layer composed of the coating composition according to any one of claims 1 to 6 adhered on the easy-adhesion layer, and the hard An antireflection film comprising: an antireflection layer bonded onto the coat layer.

Images