TWI451967B - Film with improved transmissivity - Google Patents

Description

Film with improved transmittance

The present invention relates to a film for improving transmittance, which is applied to, for example, a back surface of a positioning device (position force input device) constituting a touch panel.

The touch screen that performs input operations according to the operation instructions on the screen is widely used because of its intuitiveness, easy understanding, and simple operation. The touch screen has two functions of display and input, and the structure is usually a combination of a display device such as a liquid crystal panel and a positioning device such as a touch panel. However, since the positioning device is interposed between the user and the display device, there is a problem that the touch screen has low total light transmittance and poor visibility. For this reason, a method of improving the transmittance by attaching a film having a higher transmittance to the back surface of the positioning device by double-sided tape is generally employed.

Conventionally, an antireflection layer is laminated on such a film having improved transmittance. However, in order to increase the total light transmittance, the antireflection layer is usually a multilayer structure in which a plurality of layers of a high refractive index layer and a low refractive index layer are laminated. However, if a material having a low refractive index is used, reflection can be suppressed even if it is only a single layer structure of a low refractive index layer.

In the anti-reflection film having a single-layer structure, the anti-reflection film having a single-layer structure is formed by laminating a low-refractive-index layer by an easy-adhesion layer on the surface of the transparent substrate film. In the known anti-reflection film, the easy-adhesion layer has a refractive index of 1.50 to 1.65, a thickness of 1 to 50 nm, and a refractive index of the low refractive index layer of 1.20 to 1.50.

In the method of Patent Document 1, the total light transmittance is satisfied, but since the low refractive index layer is formed by the easy adhesion layer, the easy adhesion layer is liable to cause a problem of poor uniformity in appearance. The anti-reflection film is contemplated for use on the outermost surface of the touch screen. In order to obtain antifouling properties, it is also recommended to use a fluorine atom-containing active energy ray-curable resin as a low refractive layer material. However, in the case of using an active energy ray-curable resin containing a fluorine atom, the surface energy of the surface of the antireflection film is lowered by fluorine atoms. Then, there is a problem that the adhesion to the double-sided tape is deteriorated. On the other hand, in the method of Patent Document 1, no measures against scratch resistance are implemented, and there is a problem that the scratch resistance is poor. Further, no treatment was performed on the surface opposite to the low refractive index layer of the transparent base film. Therefore, when the film having improved transmittance is assembled to the positioning device or assembled to the positioning device, and there is a heat treatment process when it is joined to the display device, there is a haze of the film which improves the transmittance after the heat treatment. (haze) raised problem.

Accordingly, an object of the present invention is to provide a film which is excellent in adhesion to a double-sided tape, excellent in total light transmittance and scratch resistance, and which suppresses inconsistency in reflection in appearance.

All scientific and technical terms used in this specification, unless otherwise defined, are defined by those of ordinary skill in the art.

As a technical means for solving the above problems, a low refractive index layer having a refractive index lower than that of the transparent base film is directly laminated on the surface of the transparent base film. The low refractive index layer is composed of hollow ceria particles, an active energy ray-curable resin containing no fluorine atoms, a photopolymerization initiator, and alumina fine particles. The hollow ceria particles, the active energy ray-curable resin containing no fluorine atom, the photopolymerization initiator, and the alumina fine particles are 100 wt% in total, wherein the hollow ceria particles account for 28.0 to 69.0 wt%, The active energy ray-curable resin containing no fluorine atom accounts for 27.0 to 69.0% by weight, the photopolymerization initiator accounts for 1.0 to 9.0% by weight, and the alumina fine particles account for 0.1 to 0.9% by weight. That is, the low refractive index layer does not contain a surface conditioner composed of a fluororesin or an anthracene resin which positively exhibits antifouling properties and the like.

Preferably, an over coat is laminated on the back surface of the transparent substrate film. The protective coating layer is composed of an active energy ray-curable resin containing no fluorine atom, cerium oxide fine particles, and a photopolymerization initiator. Further, the cerium oxide microparticles herein refer to both solid (non-hollow) cerium oxide microparticles and hollow cerium oxide microparticles. The total amount of the fluorine-free active energy ray-curable resin, the cerium oxide fine particles, and the photopolymerization initiator is 100% by weight, wherein the fluorine-free active energy ray-curable resin accounts for 85.0 to 95.0% by weight. The cerium oxide microparticles constitute 1.0 to 10.0% by weight, and the photopolymerization initiator accounts for 1.0 to 9.0% by weight. That is, the protective coating layer does not contain a surface conditioner composed of a fluororesin or an anthracene resin which positively exhibits antifouling properties and the like. Further, the optical thickness of the protective coating layer is kλ/4 (where λ is a light wavelength of 400 to 700 nm, and k is 1, 3 or 5).

When a low refractive index layer is directly laminated on the surface of the transparent base film, the film having improved transmittance is excellent in total light transmittance, and even the touch screen of the film having the improved transmittance is excellent in total light transmittance. And it is possible to suppress inconsistency in reflection on the appearance. Further, the low refractive index layer is composed of hollow ceria particles, an active energy ray-curable resin containing no fluorine atoms, a photopolymerization initiator, and alumina fine particles, so that adhesion to the double-sided tape and scratch resistance are obtained. Excellent sex.

When a protective coating layer is formed on the back surface of the transparent base film, the haze of the film which improves the transmittance after heat treatment does not increase. Further, when the optical thickness of the protective coating layer is kλ/4 (where λ is a light wavelength of 400 to 700 nm and k is 1, 3 or 5), the total light transmittance is also excellent in addition to the above effects.

Specific embodiments of the present invention will be described in detail. The film which increases the transmittance is to directly laminate a low refractive index layer on a transparent substrate film. Further, it is also possible to laminate a protective coating on the back surface of the film having improved transmittance.

[Transparent substrate film]

The transparent base film constitutes a base material (base material) of the film which improves the transmittance. As the transparent base film, a transparent resin film or the like is used, and the surface on which the low refractive index layer is laminated is not particularly limited except for the easy adhesion layer. This is because if an easy-adhesion layer is formed between the low refractive index layer and the transparent base film, an inconsistency in appearance occurs. In order to suppress reflection of light, the refractive index (n) of the transparent base film is preferably from 1.55 to 1.70. Specific examples of the transparent base film include, for example, a poly(meth)acrylic resin, a cellulose triacetate (TAC, n=1.49) resin, and polyethylene terephthalate (PET, n= 1.65) a resin, a polycarbonate (PC, n = 1.59) resin, a polyarylate (PAR, n = 1.60), and a polyether oxime (PES, n = 1.65). Among them, from the viewpoint of versatility and the like, a cellulose triacetate resin or a polyethylene terephthalate resin is preferable. The thickness of the transparent substrate film is usually 10 to 500 μm, preferably 25 to 200 μm. In the present specification, the term "(meth)acrylic resin" means an acrylic resin or a methacrylic resin. The "(meth)acrylic acid", "(meth)acryl fluorenyl group", etc. which are mentioned later are also the same.

[Low refractive index layer]

The low refractive index layer is a functional layer as an antireflection layer. The low refractive index layer is composed of hollow ceria particles, an active energy ray-curable resin containing no fluorine atoms, a photopolymerization initiator, and alumina fine particles, and these components are mixed to form a low refractive index layer coating liquid to make low refractive index The layer coating liquid is cured under ultraviolet (UV) to form a low refractive index layer. The ratio of each of the above compositions is 100% by weight based on the total of the hollow cerium oxide fine particles, the active energy ray-curable resin containing no fluorine atom, the photopolymerization initiator, and the alumina fine particles, and is 28.0 to 69.0% by weight. The hollow cerium oxide fine particles, 27.0 to 69.0% by weight of an active energy ray-curable resin containing no fluorine atom, 1.0 to 9.0% by weight of a photopolymerization initiator, and 0.1 to 0.9% by weight of alumina fine particles, do not contain other components. Therefore, it does not contain a surface conditioner which consists of a fluororesin or an oxime resin which positively expresses antifouling performance, etc.. If other ingredients are contained, the adhesion to the double-sided tape is weakened. However, from the viewpoint of coatability, the low refractive index layer coating liquid usually contains a diluent solvent.

The refractive index of the low refractive index layer is preferably adjusted to 1.35 to 1.47, depending on the relative relationship between the refractive index of the hollow ceria particles and the refractive index of the active energy ray-curable resin containing no fluorine atoms. The film thickness after drying and curing is preferably 50 to 130 nm, and more preferably 80 to 125 nm. When the refractive index and the film thickness are outside the range, the reflectance in the visible range at 5° normal reflection is outside the range of the minimum reflectance wavelength of 450 to 650 nm, and the improvement of the total light transmittance cannot be seen.

The refractive index of the hollow ceria particles used for the low refractive index layer is preferably from 1.2 to 1.4. On the other hand, the active energy ray-curable resin which does not contain fluorine atoms preferably has a refractive index of 1.3 to 1.7. When the refractive index of the hollow ceria particles is more than 1.4, the amount of the active energy ray-curable resin containing no fluorine atoms is relatively decreased, and the coating film strength is weakened. That is, it can be seen that the scratch resistance is deteriorated. Further, when the refractive index of the hollow ceria particles is less than 1.2, the strength of the hollow ceria is weakened, and the scratch resistance tends to be deteriorated.

The blending amount of the hollow ceria particles is from 28.0 to 69.0% by weight. When it is less than 28.0% by weight, since the refractive index of the low refractive index layer becomes 1.47 or more, it is not suitable. On the other hand, when it is more than 69.0% by weight, the amount of the active energy ray-curable resin having no fluorine atom is reduced, and the strength of the coating film is weakened, which is not preferable.

Further, the average particle diameter of the hollow ceria particles preferably does not significantly exceed the thickness of the low refractive index layer. Specifically, the average particle diameter of the hollow ceria particles is preferably 0.1 μm or less. When the average particle diameter of the hollow ceria particles significantly exceeds the thickness of the low refractive index layer, light scattering or the like occurs, and the optical performance of the low refractive index layer tends to decrease. In addition, in the present specification, the "average particle diameter" is a value obtained by the following method, and the average particle size is measured by a dynamic light scattering method using a laser using a particle size distribution measuring instrument (Otsuka Electronics, PAR-III). path.

The hollow cerium oxide fine particles for the low refractive index layer can also be synthesized by a method of preparing hollow spherical cerium oxide-based fine particles having voids inside the outer casing as disclosed in Japanese Laid-Open Patent Publication No. 2006-21938. That is, the cerium oxide-based fine particles are obtained by the following steps (a), (b), (d), and (e).

Step (a): adding an aqueous solution of phthalic acid or an acidic citric acid solution to an aqueous solution of cerium in a predetermined ratio to a cerium aqueous solution to prepare a composite oxide fine particle dispersion, and adding an electrolyte at this time salt.

Step (b): An acid is added to the composite oxide fine particle dispersion to prepare a cerium oxide-based fine particle dispersion.

Step (d): The cerium oxide-based fine particle dispersion is aged in a range of from normal temperature to 300 °C.

Step (e): hydrothermal treatment is carried out in the range of 50 to 300 °C.

Further, the hollow ceria particles preferably have a surface modified by a decane coupling agent having a (meth) acrylonitrile group. By modifying the surface of the hollow cerium oxide microparticles with a decane coupling agent having a (meth) acrylonitrile group or the like to generate a covalent bond with an active energy ray-curable resin having no fluorine atom, it can be seen that the coating film strength is enhanced. tendency.

As the active energy ray-curable resin containing no fluorine atom used in the low refractive index layer, an active energy ray-curable resin containing no fluorine atom for the purpose of lowering the refractive index is used. When a fluorine atom is contained, the surface energy of the surface of the film which improves the transmittance by a fluorine atom will fall, and the adhesive force with a double-sided tape will worsen. As the active energy ray-curable resin, one type or two or more types may be selected from the group consisting of a monofunctional monomer and a polyfunctional monomer. As the monofunctional monomer, an alkyl (meth)acrylate, a (meth)acrylic acid (poly)ethylene glycol group-containing (meth)acrylate, or the like is preferable. The polyfunctional monomer may, for example, be a polyfunctional polymerizable compound containing two or more (meth)acrylonium groups, such as an ester compound of a polyhydric alcohol, a (meth)acrylic acid, or a urethane-modified acrylate. .

The blending amount of the active energy ray-curable resin containing no fluorine atom is from 27.0 to 69.0% by weight. When it is less than 27.0% by weight, the coating film strength tends to be weak, which is not preferable. On the other hand, when it is more than 69.0% by weight, since the refractive index of the low refractive index layer becomes 1.47 or more, it is not suitable.

The alumina fine particles used in the low refractive index layer are used for the purpose of improving scratch resistance. The average particle diameter of the alumina fine particles preferably does not significantly exceed the thickness of the low refractive index layer. Specifically, the average particle diameter of the alumina fine particles is preferably 0.1 μm or less. When the average particle diameter of the alumina fine particles remarkably exceeds the thickness of the low refractive index layer, scattering of light or the like occurs, and the optical performance of the low refractive index layer tends to decrease.

The blending amount of the alumina fine particles is from 0.1 to 0.9% by weight. When it is less than 0.1% by weight, the effect of improving scratch resistance is not provided. On the other hand, when it is more than 0.9% by weight, scattering due to a refractive index difference between the active energy ray-curable resin containing no fluorine atom and the alumina fine particles occurs, and the optical property of the low refractive index layer tends to decrease. .

The photopolymerization initiator used in the low refractive index layer is used to cure the low refractive index layer coating liquid under ultraviolet (UV). The blending amount of the photopolymerization initiator is from 1.0 to 9.0% by weight. If it is less than 1.0% by weight, curing is insufficient. On the other hand, when it is more than 9.0% by weight, an unnecessary amount is increased, and there is a tendency that the optical performance of the low refractive index layer is lowered. As such a photopolymerization initiator, for example, 1-hydroxy-cyclohexyl-phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinpropan-1-one can be used. Wait.

[protective coating]

The protective coating layer is composed of an active energy ray-curable resin containing no fluorine atom, cerium oxide fine particles, and a photopolymerization initiator. These components are mixed into a protective coating liquid which is cured under ultraviolet (UV) to form a protective coating. The compounding amount of each of the above-mentioned compositions is 100% by weight based on the total of the active energy ray-curable resin, the cerium oxide fine particles and the photopolymerization initiator containing no fluorine atom, and the active energy ray-curable type containing no fluorine atom. The resin is 85.0 to 95.0% by weight, the cerium oxide microparticles are 1.0 to 10.0% by weight, and the photopolymerization initiator is 1.0 to 9.0% by weight, and contains no other components. Therefore, it does not contain a surface conditioner which consists of a fluororesin or an oxime resin which positively expresses antifouling performance, etc.. When the other component is contained, when the positioning device and the film for improving the transmittance are adhered by the double-sided tape having the adhesive, the adhesion to the double-sided tape is weakened, and peeling of the positioning device may occur. However, from the viewpoint of coatability, a diluent solvent is usually contained in the protective coating liquid.

The optical film thickness of the protective coating after drying and curing is kλ/4 (where λ is a light wavelength of 400 to 700 nm, k is 1, 3 or 5), and the refractive index is 1.3 to 1.7. When the film thickness and the refractive index are out of the range, the reflectance in the visible range at 5° normal reflection is outside the range of the minimum reflectance wavelength of 450 to 650 nm, and the improvement of the total light transmittance cannot be seen. Further, in the case where the optical film thickness of the protective coating layer is thinner than 1λ/4, when the film having improved transmittance is assembled to a positioning device or the like or assembled to the positioning device, heat treatment is performed when it is joined to the display device. In the case of the step, after the heat treatment, the haze of the film which increases the transmittance increases. On the other hand, in the case of being thicker than 5λ/4, only an unnecessary thickness is increased, which is not preferable.

Further, when the film having the increased transmittance is assembled to a positioning device or the like, or assembled to the positioning device, when it is subjected to heat treatment when it is joined to the display device, it can be carried out at a temperature of 50 to 150 ° C for about 1 to 60 minutes. The difference in haze before and after the heat treatment (haze after heat treatment) - (haze before heat treatment) is preferably less than 0.5%.

As the active energy ray-curable resin which does not contain fluorine atoms used for the protective coating layer, an active energy ray-curable resin which does not contain a fluorine atom for the purpose of lowering the refractive index is used. When a fluorine atom is contained, the surface energy of the film surface which improves the transmittance by a fluorine atom will fall, and the adhesiveness with a double-sided tape will worsen. As the active energy ray-curable resin, one type or two or more types may be selected from the group consisting of a monofunctional monomer and a polyfunctional monomer. Specific examples of the monofunctional monomer are alkyl (meth)acrylate, (meth)acrylate containing (meth)acrylic acid (poly)ethylene glycol group, and the like. The polyfunctional monomer may, for example, be a polyfunctional polymerizable compound containing two or more (meth)acrylonium groups, such as an ester compound of a polyhydric alcohol, a (meth)acrylic acid, or a urethane-modified acrylate. .

The blending amount of the active energy ray-curable resin containing no fluorine atom is 85.0 to 95.0% by weight. When the amount is less than 85.0% by weight, the amount of the cerium oxide fine particles is increased, light scattering or the like occurs, and the optical properties tend to be lowered. When it is more than 95.0% by weight, when a film having a high transmittance is prepared by a roll-to-roll process, clogging may occur, which is not preferable.

In the protective coating, in order to prevent clogging in the case of preparing a film having improved transmittance by a roll-to-roll process, cerium oxide particles may be added. That is, the cerium oxide particles herein are not intended to actively reduce the refractive index of the protective coating. Therefore, the ceria particles used in the protective coating layer may also have a higher refractive index than the ceria particles used in the low refractive index layer. Specifically, in addition to the hollow ceria particles, solid ceria particles having a higher refractive index can be used. Unlike the hollow cerium oxide particles having a refractive index of 1.2 to 1.4, the solid cerium oxide particles have a refractive index of 1.4 to 1.5. When the refractive index of the cerium oxide microparticles is more than 1.5, light scattering due to the difference in refractive index between the active energy ray-curable resin having no fluorine atom and the cerium oxide microparticles tends to occur, and the optical performance tends to be lowered. When the refractive index of the cerium oxide microparticles is less than 1.2, the strength of the hollow cerium oxide microparticles is weakened, and the scratch resistance tends to be deteriorated. However, since the amount of the cerium oxide microparticles used in the protective coating layer is small, the amount of cerium oxide microparticles used in the protective coating layer is small. The effect on the deterioration of scratch resistance is small. Therefore, even if the refractive index of the cerium oxide microparticles is 1.2 or less, there is no technical problem.

The amount of the cerium oxide microparticles is 1.0 to 10.0% by weight. When it is less than 1.0% by weight, when a film having a high transmittance is prepared by a roll-to-roll process, clogging may occur, which is not preferable. On the other hand, when it is more than 10.0% by weight, light scattering due to a difference in refractive index between the active energy ray-curable resin containing no fluorine atom and the cerium oxide fine particles may occur, and optical performance tends to be lowered.

The photopolymerization initiator used in the protective coating is used to cure the protective coating liquid under ultraviolet (UV). The blending amount of the photopolymerization initiator is from 1.0 to 9.0% by weight. If it is less than 1.0% by weight, curing is insufficient. On the other hand, when it is more than 9.0% by weight, an unnecessary amount is increased, and there is a tendency that the optical properties of the protective coating layer are lowered. As such a photopolymerization initiator, for example, 1-hydroxycyclohexyl phenyl ketone or 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinil propan-1-one can be used. .

The coating method of the low refractive index layer coating liquid or the protective coating coating liquid is not particularly limited, and coating methods generally performed, such as roll coating, spin coating, dip coating, spray coating, bar-coating, etc. Any known method such as a doctor blade coating method, a die coating method, an inkjet method, or a gravure coating method can be used. At the time of coating, in order to improve the adhesion, a pretreatment such as a corona discharge treatment may be performed on the surface of the transparent substrate film in advance.

As the active energy ray source for irradiating the active energy ray, for example, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a nitrogen molecular laser, an electron beam accelerator, a radiation source such as a radioactive element, or the like can be used. In this case, the amount of irradiation of the active energy ray is preferably 50 to 5000 mJ/cm 2 in terms of the cumulative amount of light at an ultraviolet wavelength of 365 nm. When the irradiation amount is less than 50 mJ/cm 2 , the curing of the coating liquid is insufficient, which is not preferable. On the other hand, when it exceeds 5000 mJ/cm2, the active energy ray-curable resin tends to be colored, which is not preferable.

The obtained transmittance-increasing film is applied to, for example, the back surface of a positioning device constituting a touch screen in a touch screen such as a capacitive touch screen or a resistive touch screen.

Hereinafter, specific embodiments of the present invention will be further specifically described by way of Preparation Examples, Examples and Comparative Examples. Here, the film for improving the transmittance of each of the examples and the comparative examples is formed by directly laminating a low refractive index layer on a transparent base film and further laminating a protective coating on the back surface of the film having improved transmittance. Further, the adhesion, the total light transmittance, the scratch resistance, the reflection inconsistency, and the haze increase after the heat treatment in each of the examples were measured by the methods described below.

<adhesion>

(1) The low refractive index layer of the film having a high transmittance was attached to a double-sided tape No. 500 produced by Nitto Denko Corporation.

(2) According to JIS Z0237, use bench-top material testing machine ORIENTEC ( The produced STA-1150 measures the adhesion between the low refractive index layer and the double-sided tape at a peeling angle of 90°.

<Haze value, total light transmittance>

Using a haze meter NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd., measured haze value and total light transmittance.

<scratch resistance>

The steel wool of #0000 was fixed to the front end of a rubber abrasion tester manufactured by Benzo Co., Ltd., and a load of 2.5 N (255 gf) was applied, and the surface of the film to be scratched was subjected to reciprocating rubbing 10 times, and then visual observation was carried out. Surface scratches were evaluated in the following three stages.

○: There are almost no scars (the scars are less than 4)

△: There are a few scars (5 to 15 scars)

×: There are many scratches (16 or more scars)

<reflection inconsistency

Under the three-wavelength light source, a film to which a black adhesive layer was applied was attached to the back surface of the obtained antireflection film, and the evaluation was carried out in the following three stages.

○: There is almost no inconsistency

△: There is a weak inconsistency

×: There is a strong inconsistency

<Haze increase after heat treatment>

The film having improved transmittance was subjected to heat treatment at 150 ° C for 60 minutes. The difference in haze before and after the heat treatment, that is, (haze after heat treatment) - (haze before heat treatment) was evaluated.

[Preparation of low refractive index layer coating solution]

The following raw materials were used as the low refractive index layer coating liquid, and each raw material was mixed according to the compositions described in Tables 1 and 2 to prepare low refractive index layer coating liquids L-1 to L-13. Also, the values in Tables 1 and 2 are in wt%.

Hollow silica particles: Nisshin-Catalyst Chemical Co., Ltd. to produce propylene-based modified hollow cerium oxide particles V8208;

Active energy ray-curable resin containing no fluorine atom: DPHA produced by Nippon Kayaku Co., Ltd.;

Photopolymerization initiator: Ciba Specialty Chemicals Co., Ltd. produces I-907;

Alumina particles:

BYK Chemical Japan Co., Ltd. produces NANOBYK-3601

BYK Chemical Japan Co., Ltd. produces NANOBYK-3602,

BYK Chemical Japan Co., Ltd. produces NANOBYK-3610;

Solvent: isopropanol

[Preparation of protective coating solution]

The following raw materials were used as the protective coating liquid, and each raw material was mixed in the composition shown in Table 3 to prepare a protective coating liquid O-1 to O-7. Also, the values in Table 3 are in wt%.

Active energy ray-curable resin containing no fluorine atom: Nippon Chemical Co., Ltd. produces DPHA

Ceria particles:

Nisshin catalyst production into the company's production of acrylic modified hollow cerium oxide particles V8208

Nisshin Wax Catalyst Co., Ltd. produces acrylic modified hollow silica particles NAU

Photopolymerization initiator: Ciba Specialty Chemicals Co., Ltd. produces I-907

Solvent: isopropanol

Example 1-1

The low refractive index layer coating liquid (L-1) was directly coated on a 50 μm thick polyethylene terephthalate (PET) film as a transparent substrate film by a roll coating method to have a film thickness of 100 nm after curing. After drying, the film was cured by irradiating ultraviolet rays (accumulated light amount: 400 mJ/cm 2 ) with a 120 W high-pressure mercury lamp (manufactured by Nippon Battery Co., Ltd.) to obtain a film having improved transmittance.

Example 1-2

A film having improved transmittance was obtained in the same manner as in Example 1-1 except that the low refractive index layer coating liquid was L-2 and the film thickness after curing was 125 nm.

Examples 1-3

A film having improved transmittance was obtained in the same manner as in Example 1-1 except that the low refractive index layer coating liquid was L-3 and the film thickness after curing was 80 nm.

Examples 1-4

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-4.

Examples 1-5

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-5.

Example 1-6

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-6.

Example 1-7

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-7.

Comparative Example 1-1

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-8.

Comparative Example 1-2

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-9.

Comparative Example 1-3

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-10.

Comparative Example 1-4

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-11.

Comparative Example 1-5

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-12.

Comparative Example 1-6

A film having improved transmittance was obtained in the same manner as in Example 1-1, except that the low refractive index layer coating liquid was L-13.

Example 2-1

The protective coating liquid (O-1) was applied to the back surface of the transmittance-increasing film prepared in Example 1-1 by a roll coating method so that the cured optical film thickness was kλ/4 (k: 1, λ: 550nm) After drying at 138 nm, the film was cured by irradiating ultraviolet rays (accumulated light amount: 400 mJ/cm 2 ) with a 120 W high-pressure mercury lamp (manufactured by Nippon Battery Co., Ltd.) to obtain a film having improved transmittance.

Example 2-2

The protective coating has a film thickness of 0 λ/4 (k: 3, λ: 550 nm) except that the protective coating liquid is O-2. A film having improved transmittance was obtained in the same manner as in Example 2-1 except at 412 nm.

Example 2-3

The protective coating has a film thickness of k λ/4 (k: 5, λ: 550 nm) except that the protective coating liquid is O-3. A film having improved transmittance was obtained in the same manner as in Example 2-1 except for 688 nm.

Example 2-4

A film having improved transmittance was obtained in the same manner as in Example 2-1 except that the protective coating liquid was O-4.

Example 2-5

A film having improved transmittance was obtained in the same manner as in Example 2-1 except that the protective coating liquid was O-5.

Comparative Example 2-1

A film having improved transmittance was obtained in the same manner as in Example 2-1 except that the protective coating liquid was O-6.

Comparative Example 2-2

A film having improved transmittance was obtained in the same manner as in Example 2-1 except that the protective coating liquid was O-7.

The test structures of the respective examples are shown in Tables 4 to 6.

As can be seen from the results shown in Tables 3 and 4, the films having improved transmittance of Examples 1-1 to 7 were excellent in adhesion to the double-sided tape, total light transmittance, and scratch resistance. Based on this, it is also possible to achieve no inconsistency in reflection on the appearance. Further, in the films having improved transmittance of Examples 2-1 to 5, since a protective coating having a predetermined optical film thickness is formed on the back surface of the film having improved transmittance, the total light transmittance is further improved, and fogging after heat treatment can be realized. Degree does not rise.

On the other hand, in Comparative Example 1-1, the amount of the hollow cerium oxide fine particles was small, and the total light transmittance was poor. In Comparative Example 1-2, in which the amount of the hollow cerium oxide fine particles was too large, the scratch resistance (surface) was poor. In Comparative Example 1-3, since the alumina fine particles were not blended, the scratch resistance (surface) was poor. In Comparative Example 1-4, the amount of alumina fine particles blended was large, and as a result, the total light transmittance was poor. In Comparative Example 1-5, since it was not blended with the photopolymerization initiator, the scratch resistance (surface) was poor. In Comparative Example 1-6, the amount of the photopolymerization initiator blended was large, and as a result, the total light transmittance was poor.

In Comparative Example 2-1, since it did not incorporate cerium oxide microparticles, the blocking property was poor. In Comparative Example 2-2, since the photopolymerization initiator was not blended, the scratch resistance (back surface) was poor.

The detailed description of the preferred embodiments of the present invention is intended to be limited to the scope of the invention, and is not intended to limit the scope of the invention. The patent scope of this case.

In summary, this case is indeed innovative, and can enhance the above-mentioned multiple functions compared with the conventional articles. It should fully comply with the statutory invention patent requirements of novelty and progressiveness, and apply for it according to law. You are requested to approve the application for this invention patent. Inspired by the invention, to the sense of virtue.

Claims (6)

A film for increasing transmittance, which directly laminates a low refractive index layer having a lower refractive index than the transparent substrate film on a surface of the transparent substrate film; the low refractive index layer is composed of hollow ceria particles, not containing fluorine The active energy ray-curable resin, the photopolymerization initiator, and the alumina fine particles of the atom; wherein the hollow cerium oxide particles account for 28.0 to 69.0% by weight, and the active energy ray-curable resin containing no fluorine atoms accounts for 27.0~ 69.0 wt%, the photopolymerization initiator accounts for 1.0 to 9.0 wt%, and the alumina microparticles account for 0.1 to 0.9 wt%. The film for improving transmittance according to claim 1, wherein the transparent substrate film has a refractive index of 1.55 to 1.70; and the low refractive index layer has a refractive index of 1.35 to 1.47. The film for improving transmittance according to the first aspect of the invention, wherein the film thickness of the low refractive index layer is 50 to 130 nm; and the average particle diameter of the hollow ceria particles and the aluminum oxide particles is 0.1 μm or less. A film for improving transmittance according to the first aspect of the invention, wherein a protective coating layer is formed on the back surface of the transparent substrate film, the protective coating layer being an active energy ray resin containing no fluorine atom, or cerium oxide. The microparticles and the photopolymerization initiator are composed of the active energy ray-curable resin containing no fluorine atom, 85.0 to 95.0% by weight, the cerium oxide microparticles being 1.0 to 10.0% by weight, and the photopolymerization initiator being 1.0 to 9.0. Wt%, the optical film thickness of the protective coating is kλ/4, wherein λ is a light wavelength of 400-700 nm, and k is 1, 3 or 5. The film having an improved transmittance as described in claim 4 of the patent application has a refractive index of 1.3 to 1.7. The film for improving transmittance as described in claims 1-5 is used for the back surface of a positioning device constituting a touch screen.