KR101422634B1 - Optical multilayer film and image display device - Google Patents

Abstract

A first adhesive layer and a second adhesive layer are formed in this order from the base side on a substrate formed of biaxially stretched polyester. Further, a hard coat layer and an antireflection layer are formed on the second adhesive layer to form a multilayer film. When the refractive indexes of the substrate, the first adhesive layer, the second adhesive layer and the hard coat layer are eta 1, eta 2, eta 3 and eta 4, the refractive indices are adjusted so as to satisfy the following formulas (1) to (3) to suppress rainbow unevenness.

(? ¹ /? 4) ^1/2占 0.95?? ² /? 3? (? ¹ /? 4) ^{1/2 1/2} 1.05 (One)

η1 <η4 ... (2)

η2 <η3 ... (3)

The two adhesive layers can improve the bonding strength with the substrate.

Optical multilayer film, image display device

Description

TECHNICAL FIELD [0001] The present invention relates to an optical multilayer film and an image display device,

The present invention relates to an optical multilayer film and a liquid crystal display (LCD), a plasma display (PDP), an organic electroluminescence display (organic EL element), a surface electric field display (SED) And a cathode ray tube display (CRT display).

As the demand for image display devices such as LCDs, PDPs, organic EL displays, SEDs, and CRT displays increases, the demand for optical films as a main constituent member of the image display device in order to obtain its high- . The optical film is a film having various optical functions for preventing external light reflection, enlarging a viewing angle, and correcting optical unevenness.

The optical film is generally a multi-layered multi-layer film composed of a substrate as a support and an upper layer disposed thereon. The substrate is usually a transparent film containing a polymer as a main component. Among the above-mentioned bases, a base made of a polyester is characterized in that it is excellent in transparency, dimensional stability, chemical resistance, low hygroscopicity, and the like, so that demand is increasing. The upper layer contains a polymer as a main component, an additive that imparts various optical functions to prevent light reflection of the optical multilayer film, and the like. The upper layer includes, for example, an antireflection layer, a prism layer, and a light scattering layer. An infrared ray (IR) absorption film, an electromagnetic wave shielding film, a toning film, an antireflection film, an antireflection film, and an antireflection film used in PDP can be obtained by arbitrarily determining the combination of the substrate and the upper layer. Various optical films such as a film, a hard coat film and the like can be easily formed.

However, when the adhesive strength between the substrate and the upper layer is low, the upper layer can be peeled off from the substrate, causing light leakage and making it impossible to suppress light reflection. Therefore, although the bonding strength is important for the optical multilayer film, the bonding strength tends to be easily affected by the material composition of the substrate and the upper layer, the unevenness of the contact surface, the forming conditions of the respective layers, It is difficult to give. In view of the above, Japanese Patent Laid-Open No. 2001-294826, for example, discloses an optical multilayer film in which a polyester is contained in a base material and an adhesive layer containing a polyester is formed thereon to improve the bonding strength.

Further, since the optical multilayer film is made of a plurality of materials having different refractive indices such as a base material, an adhesive layer, and an upper layer, light is easily reflected at the interface. Furthermore, when light is reflected at the interface, the reflected light interferes with each other, resulting in a phenomenon in which a rainbow color appears (irregularity of iridescence). Therefore, the display quality is remarkably lowered when the optical multilayer film is used. At present, the refractive index of a conventional substrate made of polyester is relatively high, about 1.65. Therefore, a method of reducing the refractive index difference between the substrate and the layer adjacent to the substrate by increasing the refractive index of the layer adjacent to the substrate has been proposed. For example, Japanese Patent Application Laid-Open No. 2004-054161 discloses a multilayer film comprising an adhesive layer containing fine particles as a predetermined metal oxide in order to have a high refractive index. Japanese Patent Application Laid-Open No. 2005-097571 discloses a multilayer film comprising a substrate coated with a coating liquid containing a water-soluble titanium chelate compound, an aqueous polyester and water, and a hard coat layer. Japanese Patent Application Laid-Open No. 2000-111706 discloses a multilayer film comprising a base material, an adhesive layer and an upper layer which are arbitrarily determined and adjusted by taking into consideration the refractive index of the base material and the adhesive layer and the refractive index of the base layer and the refractive index of the upper layer .

In addition, the irregularity of the irregularity is caused by the thickness irregularity of each layer. Particularly, when the thickness irregularity appears in the upper layer, the reflected light becomes stronger at a predetermined thickness, and irregularity of iridescence becomes more apparent in the multilayer film, which is a problem. In view of the above, Japanese Patent Application Laid-Open No. 2003-177209 discloses a method for manufacturing a film while adjusting the refractive index and the film thickness of the adhesive layer to prevent occurrence of irregularity in the iridescence. Further, Japanese Patent Laid-Open No. 2005-178173 discloses a multilayer film comprising a primer layer obtained by adding inorganic fine particles mainly composed of titanium dioxide to at least one surface of a transparent substrate to form a high refractive index layer.

In any of the above cases, a fine particle, a chelate compound or the like is added to the adhesive layer in order to prevent rainbow unevenness. In this case, however, fine particles, chelate compounds and the like are precipitated between the substrate and the adhesive layer and between the adhesive layer and the upper layer, resulting in lowering of the adhesive strength. In addition, when a large amount of fine particles are added to increase the refractive index, the strength of each layer decreases, and as a result, the total strength of the film decreases. Japanese Patent Application Laid-Open No. 2003-177209 discloses a method of adjusting the refractive index of an adhesive layer by appropriately selecting and using a polymer having a desired refractive index. However, since most of these polymers are expensive, there is a problem because the production cost increases.

In view of the above, it is a first object of the present invention to provide a multilayer film which can suppress occurrence of irregularity of iridescence and also has various excellent optical properties such as antireflection property. A second object of the present invention is to provide an image display apparatus which can realize excellent display quality by using the optical multilayer film.

In order to achieve the above and other objects, according to the present invention, there is provided a substrate comprising a polyester having a refractive index eta 1; A first adhesive layer having a refractive index eta 2 on the substrate; A second adhesive layer having a refractive index of eta 3 on the first adhesive layer; And a surface layer having a refractive index eta 4 on the second adhesive layer. eta 1, eta 2, eta 3 and eta 4 satisfy the formula (1).

(? ¹ /? 4) ^1/2占 0.95?? ² /? 3? (? ¹ /? 4) ^{1/2 1/2} 1.05 (One)

Preferably, the surface layer is a hard coat layer, and the refractive indexes eta 1, eta 2, eta 3 and eta 4 of the substrate, the first adhesive layer, the second adhesive layer, and the surface layer satisfy the expressions (2) and (3).

η1 <η4 ... (2)

η2 <η3 ... (3)

It is preferable that the first adhesive layer and the second adhesive layer contain at least one of polyester, polyurethane and acrylic resin. The second adhesive layer preferably contains fine particles containing one of tin oxide, indium oxide, zirconium oxide, and titanium oxide as a main component. Preferably, the first adhesive layer and / or the second adhesive layer contain a compound having a plurality of carbodiimide structures in the molecule.

According to the present invention, d1 (nm) and the? 2 as the thickness of the first adhesive layer satisfy the formula (4) and the d2 (nm) as the thickness of the second adhesive layer at a visible light wavelength? ) And the above-mentioned? 3 preferably satisfy the formula (5).

-30? D1 - {? / (4 占? 2)}? 30 ... (4)

-30? D2 - {? / (4 占? 3)}? 30 ... (5)

Preferably, the polyester is polyethylene terephthalate and? 4 as a refractive index of the hard coat layer is within a range of 1.75 to 2.0. It is preferable that an antireflection layer is formed on the hard coat layer and the refractive index of the antireflection layer is 1.50 or less.

According to the present invention, preferably, the surface layer is a near infrared absorption (NIRA) coat layer, and the first adhesive layer and the second adhesive layer contain at least one of polyester, polyurethane and acrylic resin. Further, d1 (nm) as the thickness of the first adhesive layer and the above-mentioned? 2 satisfy the formula (4) at a visible light wavelength? In the range of 550 to 600 nm and d2 (nm) (5) is satisfied.

-30? D1 - {? / (4 占? 2)}? 30 ... (4)

-30? D2 - {? / (4 占? 3)}? 30 ... (5)

Further, the multilayer film of the present invention preferably includes a hard coat layer formed on the adhesive layer and the adhesive layer having a single-layer structure or a multi-layer structure formed on the substrate.

Further, the image display apparatus of the present invention is characterized by including the optical multilayer film described above.

According to the present invention, a first adhesive layer, a second adhesive layer and a surface layer are laminated in this order on a substrate formed of polyester to form a multilayer structure. As a result, an optical multilayered film can be obtained in which the interlaminar bond strength is maintained at a high level and the occurrence of irregularity of iridescence is prevented. Further, an image display apparatus capable of realizing excellent display quality by using an optical multilayer film as the constituent member can be obtained.

In order to reduce the reflectivity of light on the antireflection film, it is a recent trend to increase the refractive index of the hard coat layer. In the case of increasing the refractive index of the hard coat layer, it is necessary to increase the refractive index of the adhesive layer in order to prevent irregularity in the irregularity (in this case, the adhesive layer has a single layer structure). In this case, in order to increase the refractive index of the adhesive layer, the component ratio of the metal oxide particles in the adhesive layer is increased, and thus the strength of the adhesive layer is reduced. According to the present invention, since the adhesive layer includes two layers, irregularity irregularity can be prevented without increasing the refractive index of each adhesive layer. This makes it possible to obtain an optical multilayer film which can maintain the interlaminar bond strength to a desired level and suppress the occurrence of irregularity of iridescence.

Further, according to the present invention, the first adhesive layer, the second adhesive layer and the NIRA coat layer are laminated in this order on the base material side to constitute a multi-layer structure. This prevents light from reflecting on the interface between the base material and the NIRA coat layer, thereby preventing irregularity of iridescence.

Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments.

First, the present invention will be described according to a first embodiment. 1, the optical multilayer film (hereinafter referred to as a multilayer film) 10 of the present invention comprises a substrate 11 formed of polyester in the form of a film, a substrate 11 formed on the substrate 11, The first adhesive layer 12, the second adhesive layer 13, the hard coat layer 14, and the antireflection layer 15. The hard coat layer 14 and the antireflection layer 15 are surface layers. The first adhesive layer 12 and the second adhesive layer 13 may be formed on both sides of the substrate 11 as well as one side thereof. The adhesive layer means a layer formed between the substrate and the surface layer, and has a function of improving the adhesion.

For example, according to a second embodiment of the present invention, as shown in Fig. 2, the multilayer film 20 of the present invention is additionally provided on the other surface of the substrate 11 of the multilayer film 10 shown in Fig. 1 When the first adhesive layer 16, the second adhesive layer 17 and the near infrared absorbing (INRA) coat layer 18 are formed in this order, the NIRA coat layer 18 can be formed. The multilayer film 20 shown in Fig. 2 can be preferably used as an antireflection film for a plasma display panel (PDP).

3, the multilayer film 30 of the present invention is formed on the base 11 of the multilayer film 20 on the opposite side of the first adhesive layer 16 in order An adhesive layer 25, a hard coat layer 26 and an antireflection layer 27 formed thereon. The adhesive layer 25 includes a first adhesive layer 12 and a second adhesive layer 13 as one layer. The multilayered film 30 can also be preferably used as an antireflection film for PDP.

1 to 3, the hard coat layer 14 and the NIRA coat layer 18 are considered as surface layers. This surface layer is included in the intermediate manufacturing stage as well as the final manufacturing stage of the multilayer film. In the case of the intermediate stage, the antireflection layer 15 or another top layer may be formed on the surface layer of the present invention.

When the refractive index of the base material 11 is eta 1 and the refractive index of the first adhesive layer 12 is eta 2 and the refractive index of the second adhesive layer 13 is eta 3 and the refractive index of the hard coat layer 14 as the surface layer is eta 4, Satisfies the following equations:? 1 <? 4 and? 2 <? 3. Therefore, reflection of light at the interface between the hard coat layer 14 and the substrate 11 can be prevented, and occurrence of irregularity of iridescence due to interference of light can be prevented. According to the present invention, it is possible to obtain a multilayer film (10) having a multi-layer structure and preventing irregularity of irregularity due to interference of light at each interface by adjusting the refractive index of the adjacent layers to satisfy the above conditions. The refractive indices eta 1 to eta 4 of the respective layers 11 to 14 can be adjusted by adding fine particles to the components of the layers 11 to 14 or arbitrarily determining the refractive index of the polymer used as the binder. At this time, the kind of the fine particles is determined in an arbitrary manner and the content of the fine particles is controlled. The refractive index measurement method may be a known method and is not particularly limited. The refractive indices eta 1 to eta 4 of the layers 11 to 14 of the present invention are values based on visible light having a wavelength in the range of 550 to 600 nm.

Further, it is preferable that? ² /? 3 satisfies the following formula:? ¹ /? 4 ^1/2? 0.95?? ² /? 3? ^{1/2 × 0.97≤η2 / η3≤ (η1 /} η4) 1/2 × 1.03, and most preferably ^{(η1 / η4) 1/2 × 0.98≤η2} / η3≤ (η1 / η4) 1/2 × 0.12 to be. Therefore, reflection of light on the interface between the substrate 11 and the hard coat layer 14 in the multilayered film can be prevented, and occurrence of irregularity of iridescence due to interference of light in the multilayered film can be prevented.

D1 (nm) as the thickness of the first adhesive layer 12 and eta 2 as the refractive index of the first adhesive layer 12 satisfy the relationship of -30? D1 - {? / (4? 2)}? 30, and d2 as the thickness of the second adhesive layer 13 and eta 3 as the refractive index thereof preferably satisfy the expression -30? D2 - {? / (4 x? 3)}? d1 and? 2 satisfy the following expression: -20? d1 - {? / (4 x? 2)} 20 and d2 and? 3 satisfy the expression -20? d2 - Is more preferable. d1 and eta 2 satisfy the expression -10? d1 - {? / (4 占 侶 2)? 10 and d2 and? 3 satisfy the expression -10? d2 - Is most preferable. As described above, the multilayer film having the first adhesive layer 12 and the second adhesive layer 13 whose thicknesses and refractive indexes are respectively adjusted to prevent reflection of light on the interface further suppresses occurrence of irregularity of iridescence due to interference of light remarkably do.

The following formulas (1) to (3) show the relationship between eta 1, eta 2, eta 3 and eta 4.

(1) (? 1 /? 4) ^1/2 x 0.95?? ² /? 3? (? ¹ /? 4) ^1/2 1.05

(2)? 1 <? 4

(3)? 2 <? 3

The following equation (4) shows the relationship between the thickness of the first adhesive layer 12 and the refractive index, and the following equation (5) shows the relationship between the thickness of the second adhesive layer 13 and the refractive index.

(4) -30? D1-? / {(4? 2)}? 30

(5) -30? D2? / {(4?? 3)}? 30

It is considered that the reflection of light on the interface between the substrate 11 and the hard coat layer 14 can be prevented when the following equation is satisfied:? ² /? 3 = (? ¹ /? 4) ^1/2 ,? ²占 d1 = ? / 4, and? 3 x d2 =? / 4. Each expression is described in a book of general optical fields such as "Optical Thin Film (Kougaku Hakumaku)" (p.98, edited by Shiro Fujiwara, published by KYORITSU SHUPPAN CO., LTD., 1986). Therefore, if the value is adjusted to satisfy the above formula, the reflectivity of light on the interface becomes theoretically zero. It is insufficient to change the kind of the material or add the fine particles in order to bring the reflection of light on the layer close to the theoretical value. Further, in the case of producing the multilayer film 10 having the multilayer structure shown in Fig. 1, since the printing of the multilayer film 10 becomes complicated, it becomes more difficult to bring the reflection of light on the layer close to the theoretical value. However, even when a slight deviation occurs in the above equation, it is possible to actually prevent reflection of light at the interface and occurrence of irregularity of iridescence. Therefore, according to the present invention, the equations (1), (4) and (5) applicable to the multilayered film having a multilayered structure are stipulated by considering the allowable range of the equation, and a more appropriate value is defined. As a recent tendency, the refractive index of the hard coat layer is increased in order to reduce the reflectivity of light on the antireflection film. Therefore, if the refractive index of the hard coat layer is set to satisfy? 1 <? 4 as shown in the formula (2), the reflectivity of light can be reduced. Further, if the refractive index of the hard coat layer is set so as to satisfy? 2 <? 3 as shown in the formula (3), iridescence nonuniformity can be reduced.

[materials]

The polyester to be used as the substrate 11 is not particularly limited, and any known polyester may be used. Specific examples thereof include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and polybutylene naphthalate. Of these, polyethylene terephthalate is preferably used from the viewpoints of production cost, mechanical strength and the like.

The base material (11) of the present invention is preferably stretched biaxially. The biaxial stretching means stretching the base material 11 in both directions by considering the width direction and the longitudinal direction of the base material 11 as one axis. As described above, since the biaxial orientation of the base material 11 stretched by biaxial orientation is sufficiently controlled, the base material 11 has excellent mechanical strength. The stretching ratio is not particularly limited, but the stretching ratio in one direction is preferably 1.5 to 7 times, more preferably 2 to 5 times. In particular, since the molecular orientation of the base material 11 stretched by biaxial stretching at a stretching ratio of 2 to 5 times in one direction is more effectively controlled, the base material 11 has a very excellent mechanical strength and is suitable. When the stretching ratio of the base material 11 is 1.5 times or more, an effective mechanical strength can be obtained as compared with the case where the stretching ratio is less than 1.5 times. On the other hand, if the stretching ratio is 7 times or less, a uniform thickness can be obtained as compared with the case where the stretching ratio exceeds 7 times.

The thickness of the substrate 11 is preferably in the range of 30 to 400 mu m, more preferably in the range of 35 to 350 mu m. The thickness of the base material 11 can be easily adjusted by controlling its stretching ratio. The base material 11 as described above has transparency and various optical properties, is light in weight and easy to handle. The base material 11 having a thickness of 30 占 퐉 or more is not too thin and easy to handle. Further, the base material 11 having a thickness of 400 m or less is considered to have a sufficient thickness, and it is easy to make the image display device smaller and lighter, and does not increase the manufacturing cost. The substrate 11 of the present invention may contain an ultraviolet (UV) absorber and an oxidation inhibitor. In particular, for use of the antireflection film for PDP, it is preferable to incorporate the UV absorber into the substrate 11 as disclosed in JP-A-2006-212815.

[First adhesive layer and second adhesive layer]

The first adhesive layer 12 and the second adhesive layer 13 each comprise a layer containing at least one of a polyester, a polyurethane and an acrylic resin. The first adhesive layer 12 and the second adhesive layer 13 may contain fine particles containing at least one of tin oxide, indium oxide, zirconium oxide and titanium oxide as main components, respectively, for the purpose of adjusting the reflectance have. Here, the main component means a component having a percentage of fine particles of 50% or more. The first adhesive layer 12 is formed on the substrate 11. In addition, as described above, the second adhesive layer 13 is formed on the first adhesive layer 12 and functions as an antireflection layer.

A polyester is a collective term for a polymer having an ester bond in its main chain. Generally, the polyester is obtained by a reaction between a polycarboxylic acid and a polyol. The polycarboxylic acid is, for example, fumaric acid, itaconic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid and the like. Of these, terephthalic acid and naphthalene dicarboxylic acid are preferably used. The sodium sulfoisophthalate copolymerized by copolymerization is preferable because it can be used as a water-soluble or water-dispersible polyester.

Examples of the polyol include polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, hexanetriol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, Ethylene oxide adducts (NC-1900, manufactured by Nippon Nyukazai Co., Ltd., etc.) and polyether polyols. (Such as Finetex ES 650 and ES2200 (product name, product of Dainippon Ink & Chemicals, Inc.), Vylonal MD1400 and MD1480 (product name, product of TOYOBO., LTD.), Plus coat Z- Soluble polymer such as polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, polyvinyl alcohol, and polyvinyl alcohol.

A polyurethane is a collective term for a polymer having a urethane bond in its main chain. Generally, polyurethanes are obtained by the reaction between a polyisocyanate and a polyol. Polyisocyanates include TDI, MDI, NDI, TODI, HDI, and IPDI. Polyols include ethylene glycol, propylene glycol, glycerin, hexanetriol, and the like. According to the present invention, as the polyisocyanate, a polymer obtained by reacting a polyisocyanate with a polyol to obtain a polyurethane, and subjecting the polyurethane to a chain extension process to increase its molecular weight can be used. Polyisocyanates, polyols and chain extension processes are described, for example, in "Handbook of polyurethane resins" (edited by Keiji IWATA, published by Nikkan Kogyo Shimmbun Ltd., 1987). As commercial products, Superflex 830, 460, 870, 420 and 420 NS (product name, product of Dai-ichi Kogyo Seiyaku Co., Ltd.), Vondic 1370 NS and 1320 NS, and Hydran AP-40 F (product name, Daininppon Ink & Chemicals, Inc.). Products), and other polyurethane water dispersions.

The acrylic resin is a polymer containing acrylic acid, methacrylic acid and derivatives thereof as its components. As the acrylic resin, acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylamide, acrylonitrile, hydroxy acrylate and the like as main components are copolymerized with the above- And a polymer that is copolymerized with a monomer that can be used. Monomers include, for example, styrene, divinylbenzene, and the like. As commercial products, acrylic water dispersions such as Jurymer ET325, ET410 and SEK301 (product name, manufactured by Nihon Junyaku Co., Ltd.), Bon Coat AN117 and AN226 (product name, manufactured by Dainippon Ink & Chemicals, Inc.) are available.

As described above, in the case of using fine particles for the purpose of adjusting the refractive index or for other purposes, the deterioration of the light transmittance of the first adhesive layer 12 and the second adhesive layer 13 due to the large impurities formed by the aggregation of the fine particles There is a possibility. In this case, it is possible to prevent coagulation of the fine particles by appropriately determining the diameter and kind of the fine particles. In order to effectively prevent aggregation of fine particles, the average diameter of the fine particles is preferably in the range of 5 to 200 nm, more preferably in the range of 10 to 100 nm, and most preferably in the range of 15 to 70 nm. When fine particles having an average diameter of 200 nm or less are used, there is no possibility that the transparency and light transmittance of the first and second adhesive layers 12 and 13 visible to the naked eye decrease. In addition, since fine particles having an average diameter of 5 nm or more can be obtained at a lower cost than fine particles having an average diameter of less than 5 nm, beneficial results can be obtained from the viewpoint of production cost. In addition, since fine particles having an average diameter of 5 nm or more are used, there is less possibility of reducing the transparency of the first and second adhesive layers 12 and 13 because the fine particles aggregate to form large impurities as compared with the fine particles having an average diameter of less than 5 nm. According to the present invention, the average diameter of the fine particles is an average diameter of 50 fine particles arbitrarily selected. At this time, the diameter of the fine particles is equal to the diameter of the circle having the same area as the fine particles captured by the scanning electron microscope.

The fine particles to be used for the first adhesive layer 12 and the second adhesive layer 13 are preferably tin oxide, zirconium oxide, or titanium oxide among the above-mentioned fine particles from the viewpoints of easiness of availability and relatively low cost.

It is preferable to use tin oxide (IV) having a composition of SnO ₂ . Further, tin oxide is preferably doped with antimony or the like as a dopant. As described above, the doped tin oxide has conductivity, so that reduction of the surface resistivity of the multilayer film can be suppressed and impurities such as dust can be prevented from adhering to the surface of the multilayer film. SN-38F, SN-88F, SN-100F, TDL-S and TDL-1 (both of these products are available from ISHIHARA SANGYO KAISHA, LTD.) As antimony doped tin oxide. These can be preferably used in the present invention. Tin oxide using phosphorus as a dopant may also be preferably used.

Zirconium oxide (IV) having a composition of ZrO ₂ is preferably used. For example, NZS-20A and NZS-30A (both manufactured by NISSAN CHEMICAL INDUSTRIES, LTD.) And the like. Titanium oxide (IV) having a composition of TiO ₂ is preferably used. There are rutile type (high temperature tetragonal) titanium dioxide and anatase type (low temperature tetragonal) titanium dioxide according to the quartz structure, but titanium dioxide is not particularly limited. Titanium dioxide having a surface-treated surface can also be used. IT-S, IT-O and IT-W (both manufactured by Idemitsu Kosan Co., Ltd.) and TTO-W-5 (manufactured by ISHIHARA SANGYO KAISHA, LTD.) Are preferably used as the titanium dioxide .

Although the molecular weight of the polymer used for the first and second adhesive layers 12 and 13 is not particularly limited, for the purpose of realizing excellent handling properties and forming a layer having a preferable flat surface, the weight average molecular weight is generally 3,000 to 1,000,000 Is preferable. When the polymer has a weight average molecular weight of 3,000 or more, the strength of the first adhesive layer 12 and the second adhesive layer 13 is less likely to be insufficient as compared with a polymer having a weight average molecular weight of less than 3,000. When the weight average molecular weight of the polymer is 1,000,000 or less, it is not difficult to apply the polymer due to the decrease in fluidity, as compared with the polymer having a weight average molecular weight of more than 1,000,000. Therefore, the surface flatness of the first and second adhesive layers 12 and 13 Can be prevented from deteriorating.

It is preferable that the first and second adhesive layers 12 and 13 each include a compound having a plurality of carbodiimide structures in the molecule. In the case where each of the first and second adhesive layers 12 and 13 includes such a compound, if the first and second adhesive layers 12 and 13 contain the respective fine particles, it is possible to prevent the fine particles from being peeled off. The carbodiimide type compound is not particularly limited as long as it has a plurality of carbodiimide groups. Also, the number of carbodiimide groups is not limited. In general, polycarbodiimides are synthesized by condensation of organic diisocyanates. The organic group of the organic diisocyanate used for the synthesis is not particularly limited and may be an aromatic group, an aliphatic group, or a mixture thereof. From the viewpoint of reactivity, an aliphatic group is particularly preferable. The synthetic materials include organic isocyanates, organic diisocyanates, and organic triisocyanates.

The organic isocyanate may be an aromatic isocyanate, an aliphatic isocyanate, or a mixture thereof. Specific examples thereof include 4,4-diphenylmethane diisocyanate, 4,4-diphenyldimethylmethane diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexa Methylene diisocyanate, cyclohexane diisocyanate, xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,3-phenylene diisocyanate and the like can be used have. The organic monoisocyanate may be isophorone isocyanate, phenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, or naphthyl isocyanate. As a carbodiimide compound applicable to the present invention, for example, Carbodilite V-02-L2 (product name, manufactured by Nisshinbo Industries, Inc.) may be used as a commercially available product.

The amount of the carbodiimide compound of the present invention to be added to the binder is preferably from 1 to 200% by mass, and more preferably from 5 to 100% by mass. When the addition amount of the carbodiimide compound is 1% by mass or more, peeling of the fine particles contained in the first and second adhesive layers 12 and 13 can be sufficiently prevented as compared with the case where the addition amount is less than 1% by mass. When the addition amount of the carbodiimide compound is 200 mass% or less, the deterioration of the unevenness of the surfaces of the first and second adhesive layers 12 and 13 can be prevented as compared with the case where the addition amount exceeds 200 mass% have.

The first and second adhesive layers 12 and 13 may include fine particles which function as a matting agent for the purpose of improving lubricity and the like. Here, the lubricity means the sliding ability of the film. The matting agent may be organic or inorganic fine particles. For example, as a matting agent, there are polymer fine particles such as polystyrene, polymethyl methacrylate, silicone and benzoguanamine, and inorganic fine particles such as silica, calcium carbonate, magnesium oxide and magnesium carbonate. Of these, polystyrene, polymethylmethacrylate and silica are preferably used from the viewpoint of improvement in lubricity and realization of low cost.

In order to provide a desirable lubricity, the average diameter of the fine particles of the matte is preferably in the range of 0.01 to 12 mu m, more preferably 0.03 to 9 mu m. When the average diameter of the fine particles of the matte is 0.01 탆 or more, preferable lubricity can be realized as compared with the case where the average diameter is less than 0.01 탆. Further, when the average diameter of the particles made of matte is 12 μm or less, there is no possibility that the display quality of the image display device will deteriorate as compared with the case where the average diameter exceeds 12 μm. The amount of the matting agent to be added may vary depending on the average diameter of the fine particles. The amount of the matting agent to be added is preferably in the range of 0.1 to 30 mg / m ² , more preferably in the range of 0.5 to 20 mg / m ² , for the purpose of realizing the improvement effect of excellent lubricity and preventing deterioration of the display quality of the image display apparatus. . When the addition amount of the mat agent is 0.1 mg / m &lt; ² &gt; or more, the effect of improving lubricity can be realized. When the addition amount of the matting agent is 30 mg / m ² or less, deterioration of the display quality of the image display apparatus can be prevented. The average diameter of the fine particles of the mat according to the present invention is measured by the same method as the method of measuring the average diameter of the above-mentioned fine particles.

The first adhesive layer 12 and the second adhesive layer 13 may contain various additives such as a surfactant. The surfactant is, for example, a known anionic, nonionic or cationic type. Surfactants applicable to the present invention are described, for example, in "Handbook of Surfactants (Kaimen Kasseizai Binran)" (edited by Ichiro Nishi et al., Edited by Sangyo-Tosho, 1960). When a surfactant is used, the amount thereof is preferably in the range of 0.1 to 30 mg / m ² , and more preferably in the range of 0.2 to 10 mg / m ² . When the addition amount of the surfactant is 0.1 mg / m ² or more, the effect of the surfactant can be obtained as compared with the case where the addition amount is less than 0.1 mg / m ² . Therefore, it is possible to prevent repulsion between the first adhesive layer 12 and the second adhesive layer 13. Further, when the addition amount of the surfactant is 30 mg / m ² or less, surface deterioration of the first adhesive layer 12 and the second adhesive layer 13 can be prevented as compared with the case where the addition amount exceeds 30 mg / m ² .

A static electricity can be prevented by using an antistatic agent for the first adhesive layer 12 and the second adhesive layer 13. The antistatic agent is not particularly limited, and examples of the antistatic agent include an electron conductive polymer such as polyaniline and polypyrrole, an ion conductive polymer having a carboxyl group and a sulfonate group in its molecular chain, and conductive fine particles. The conductive fine particles may be ordinary fine particles having tin oxide and indium oxide as the above-mentioned main components. For example, the conductive fine particles of tin oxide described in JP-A-61-020033 can be preferably used in terms of conductivity and transparency. When an antistatic agent is used, the addition amount of the first adhesive layer 12 and the second adhesive layer 13 measured in an RH atmosphere at 25 ° C and 30% is 1 × 10 ⁵ to 1 × 10 ¹³ Ω Range. &Lt; / RTI &gt; When the surface resistances of the first and second adhesive layers 12 and 13 are set to 1 10 ⁵ Ω or more, the use of a large amount of the antistatic agent can be avoided compared with the case where the surface resistance is less than 1 × 10 ⁵ Ω have. Therefore, the transparency of the first and second adhesive layers 12 and 13 can be reduced. Further, if the surface resistance is not more than 1 × 10 ¹³ Ω, in comparison with the case that the surface resistance exceeds 1 × 10 ¹³ Ω, it is possible to realize the effect of preventing the power loss. Therefore, there is no possibility that dust or the like adheres to the surfaces of the first adhesive layer 12 and the second adhesive layer 13.

It is preferable to use a lubricant to improve the lubricity of the first adhesive layer 12 and the second adhesive layer 13. [ The lubricant is preferably an aliphatic wax, and the amount thereof is preferably in the range of 0.1 to 30 mg / m ² , and more preferably in the range of 0.5 to 10 mg / m ² . When the addition amount of the lubricant is 0.1 mg / m ² or more, sufficient lubricity can be realized. Further, when the addition amount of the lubricant is 30 mg / m ² or less, it is possible to prevent the decrease in the bonding strength between the first adhesive layer 12 and the second adhesive layer 13. The aliphatic wax applicable to the present invention is described in detail in Japanese Patent Application Laid-Open No. 2004-054161.

The various additives described above are added to both the first adhesive layer 12 and the second adhesive layer 13 for surface improvement. However, when the second adhesive layer 13 is formed successively after the formation of the first adhesive layer 12, an additive may be added only to the second adhesive layer 13.

A method of forming the first and second adhesive layers 12 and 13 will be described. In this embodiment, the first and second adhesive layers 12 and 13 are sequentially formed as follows. A coating liquid in which a polymer, a fine particle, an additive and a solvent are mixed together is applied to the surface of a substrate 11 (biaxially stretched polyethylene terephthalate film) to form a coating layer, and then the coating layer is dried. The solvent, that is, the solvent for the coating liquid may be water, toluene, methyl alcohol, isopropyl alcohol, methyl ethyl ketone, or a mixture thereof. The coating-receiving solvent may be water. In this case, the water functions as a solvent for the coating solution. As described above, when water is used as a solvent for coating application, the manufacturing cost can be reduced and the manufacturing process can be facilitated.

It is preferable to apply the coating liquid to the base material 11 stretched by biaxial stretching as described above. Alternatively, after the first adhesive layer 12 is formed on the base material 11 stretched in one direction, It is also preferable to form the second adhesive layer 13 in an off-line manner on the base material 11 on which the first adhesive layer 12 is formed. Here, one axis is considered to be one of the width direction and the length direction of the substrate 11. [ Following the biaxial stretching of the base material 11, the order of the width direction and the longitudinal direction is not limited.

The method of forming the first adhesive layer 12 and the second adhesive layer 13 is not particularly limited as long as a layer having a desired thickness can be obtained. Thus, the application method is not limited, and may be a known method used for forming a thin film. Examples of the method include a dipping method, a spinner method, a spray method, a roll coater method, a gravure method, a wire bar method, a slot extrusion coater method (single layer and multilayer), and a slide coater method. The application of the first adhesive layer 12 and the second adhesive layer 13 may be performed not only by sequential application on-line but also by off-line independent application. The above method can be used to form the layer of the present invention including the first and second adhesive layers 12 and 13, the hard coat layer 14 and the antireflection layer 15. [

[Hard coat layer]

The hard coat layer 14 is preferably formed of an energy-curable polymer or a thermosetting polymer. In particular, energy curable polymers are preferably used. Since the energy-curable polymer is cured by irradiation with an active energy ray, the energy-curable polymer is less damaged than heat-curable polymer using heat as energy for curing. Thus, the energy-curable polymer is advantageous in that it can form a layer having high transparency.

The energy curable polymer used to form the hard coat layer 14 is described. The energy-curable polymer is preferably a curable polymer having two or more acrylic groups in the molecule. For example, there may be mentioned ethylene glycol diacrylate, 1,6-hexanediol diacrylate, bisphenol-A diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, Polyol polyacrylates such as erythritol tetraacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate; A polyfunctional urethane acrylate obtained by reaction between a hydroxyl group-containing acrylate such as hydroxyethyl acrylate and a polyisocyanate curable polymer; And polyfunctional epoxy acrylates obtained by reaction between a hydroxyl group-containing acrylate (methacrylate) such as hydroxyethyl acrylate and a polyepoxy-curable polymer. A polymer having an ethylenic unsaturated group in its side chain can also be used.

When an energy-curable polymer is used, it is preferable to irradiate the application layer with ionizing radiation such as radiation, gamma (gamma) radiation, alpha (alpha) radiation, electron radiation or ultraviolet radiation as activation energy. As a result, the polymer can be effectively and effectively cured, so that the hard coat layer 14 having a sufficient hardness can be formed. In the case of forming the hard coat layer 14, it is preferable to apply the coating liquid for forming the hard coat layer 14 to the second adhesive layer 13 to form a coated layer, and then irradiate the coated layer with ultraviolet rays It is right. This makes it possible to obtain the hard coat layer 14 having uniform thickness in a short period of time and having no unevenness in optical characteristics. If the coating liquid is obtained by preliminarily diluting a desired energy-curable resin, a polymerization initiator or the like with a solvent, a coating layer having a uniform thickness can be easily formed, and preferable results are obtained.

According to the present invention, one type of polymerization initiator may be used, or two or more types of polymerization initiators may be used in combination. The number of polymerization initiators is not particularly limited. The amount of the polymerization initiator to be added is not particularly limited, but the addition amount is preferably in the range of 0.1 to 15 mass% of the total amount of the curable polymer having an ethylenically unsaturated group and the curable polymer having a ring-opening polymerizable group contained in the curable polymer composition, And more preferably 1 to 10% by mass.

It is preferable that inorganic fine particles are added to the binder used for forming the hard coat layer 14 so that the refractive index thereof is in the range of 1.75 to 2.00. Generally, since the refractive index of the inorganic fine particles is as high as about 1.8 to 2.7, the refractive index of the layer to be formed can be adjusted to a high level within the above-mentioned range. When the refractive index of the hard coat layer 14 is 1.75 or more, the reflectivity of light can be easily reduced on the hard coat layer 14 as compared with the case where the refractive index is less than 1.75. Further, when the refractive index is 2.00 or less, there is no possibility that the hard coat layer 14 is retreated, as compared with the case where the refractive index exceeds 2.00, and deterioration of the defect resistance can be prevented.

As an example of the composition capable of forming the hard coat layer 14 having a high refractive index, the polyfunctional acrylic acid ester-based monomer used as the polymer component contains inorganic fine particles such as alumina and titanium oxide. This example is disclosed in Japanese Patent No. 1815116. In addition to this, a photopolymerizable compound composition containing an inorganic fine particle having alumina is described in Japanese Patent No. 1416240. These substrates are also applicable to the present invention. However, the hard coat layer 14 of the present invention is not limited to the above examples.

The hard coat layer 14 having a high refractive index can be formed using a polymer having a high refractive index. The polymer having a high refractive index may be, for example, a polymer having a cyclic group, a polymer having a halogen atom other than fluorine, a cyclic group and a polymer having both halogen atoms other than fluorine. Examples of the cyclic group include an aromatic group, a heterocyclic group, and an alicyclic group.

The thickness of the hard coat layer 14 is not particularly limited, but its thickness is preferably in the range of 0.5 to 10 mu m, more preferably in the range of 1 to 5 mu m. This makes it possible to realize physical properties such as desired optical characteristics and excellent defect resistance and to maintain a high adhesive strength on the interface between the second adhesive layer 13 and the hard coat layer 14. [ When the thickness of the hard coat layer 14 is 0.5 占 퐉 or more, sufficient physical properties and excellent defect resistance can be provided. Further, when the thickness is 10 탆 or less, the influence of hardening and absorption of the hard coat layer 14 can be reduced, and a high adhesive strength can be maintained at the interface between the second adhesive layer 13 and the hard coat layer 14 .

[Antireflection layer]

In order to provide an antireflection function, the refractive index of the antireflection layer 15 is lower than that of the hard coat layer 14. In order to form a layer having a low refractive index, adjustment is performed using a material having a low refractive index such as a fluorine-based material and a silicon material as a binder. The refractive index of the antireflection layer 15 is preferably 1.50 or less. In this case, the antireflection property can be improved as compared with the case where the refractive index exceeds 1.50. In forming the antireflection layer 15, a commercially available coating material for forming an antireflection film may be used. As a coating material for forming such a layer having a low refractive index, there is a commercially available coating material having a low refractive index such as TT1148, TU2111 and TU2153 (all of them are products of JSR Corporation).

The multilayer film obtained as described above has a high interlaminar bond strength and prevents interference of light on the interlayer interface, so that the occurrence of irregularity of irregularity is reduced. As described above, a multilayer film having excellent optical characteristics can be used as an antireflection film having excellent display quality in various image display devices.

The multilayer film of the present invention can be used as an optical film used in a liquid crystal display, a plasma display (PDP), an organic EL display, a surface electric field display (SED) and a CRT display. These image display devices are disclosed in, for example, "Display Advanced Technology (Display Sentan Gijyutsu)" (edited by Chizuka Tani, published by Kyoritsu Publications Inc., 1998), "EL, PDP and LCD Display" (issued by TORAY RESEARCH CENTER, 2001), "Color Liquid Crystal Display (Color Ekisyo Display)" (edited by Shunsuke Kobatashi, published by Sangyo Tosho Publishing Co., Ltd., 1990).

The multilayer film of the present invention can be preferably used as a film filter obtained by combining together an optical film such as an antireflection film, an IR absorbing film, an electromagnetic wave shielding film, and a toned film used for a PDP. These films are described, for example, in "Electric Journal", p. 74, August, 2002.

Next, each layer of the optical multilayer film 20 having the NIRA coat layer 18 will be described. The first adhesive layer 12, the second adhesive layer 13, the hard coat layer 14 and the antireflection layer 15 are the same as those of the multilayer film 10 having the hard coat layer 14 described above. Therefore, detailed description thereof will be omitted. The material of the first adhesive layer 16 for forming the NIRA coat layer 18 is the same as that of the first adhesive layer 12 of the multilayer film 10.

The material of the second adhesive layer 17 for forming the NIRA coat layer 18 is the same as that of the second adhesive layer 13 of the multilayered film 10.

The NIRA coat layer 18 includes a near infrared ray blocking agent and an organic binder. The near infrared ray blocking agent is a known one and is not particularly limited. As the near-infrared ray blocking agent, for example, metal oxides such as indium tin oxide, indium oxide, tin oxide, silicon oxide, aluminum oxide, zinc oxide and tungsten oxide; Organic pigments such as phthalocyanine pigments, anthraquinone pigments, naphthoquinone pigments, cyanine pigments, naphthalocyanine pigments, polymer condensed azo pigments and pyrrole pigments; A dithiol system, and an organometallic complex such as a mercaptonaphthol system. One type of near-infrared ray blocking agent may be used alone, or two or more types of near-infrared ray blocking agents may be used in combination.

Irg-02, IRG-022, IRG-023 and IRG-040 (all of these are products of NIPPON KAYAKU CO., LTD.), IR1, IR2, IR3, IR4, TX- TX-EX-812K and TX-EX-905B (all of which are available from NIPPON SHOKUBAI CO., LTD.), SIR-128, SIR-130, SIR- 132 and SIR- CIR-1080 and CIR-1081 (both manufactured by Japan Carlit Co., Ltd.), NKX-1199 (manufactured by Nippon Kanko Shikiso Research Laboratory), and MIR101 (manufactured by Midori Kagaku Co., Ltd.).

In the case of forming a layer containing a near-infrared blocking agent on a substrate, a layer can be formed using an organic binder in which a near-infrared blocking agent is dissolved or dispersed. As the organic binder, for example, polyolefin (polyethylene, polypropylene, etc.), polystyrene compounds such as polystyrene and poly (? -Methylstyrene); Styrene copolymers such as styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-maleic acid copolymers and styrene-maleic acid ester copolymers; Polyvinyl compounds such as polyvinyl chloride, polyvinyl alcohol and polyvinyl acetate; Polyalkyl methacrylates such as polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate and polybutyl propyl methacrylate; Polyethers such as polyoxymethylene and polyethylene oxide; Polyesters such as polyethylene succinate, polybutylene adipate, polylactate, polyglycolic acid, polycaprolactone, and polyethylene terephthalate; Natural polymers such as cellulose, starch and rubber; Polyamides such as 6-nylon and 6,6-nylon; Polyurethane, epoxy resin, polyacrylate, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbons, aromatic oils and their modified halogens. One kind of organic binder may be used, or two or more kinds of organic binders may be used in combination. The curable monomer may be cured by applying a curable monomer to form a layer, and then irradiating with an active energy ray such as heat or ultraviolet rays.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. The following examples and comparative examples are considered as examples of the present invention, and the present invention is not limited thereto. Therefore, the kind of the material, the proportion of the material, the treatment and the like can be arbitrarily changed within the essence of the present invention. Hereinafter, the production method and conditions will be described in detail in Example 1, and in the other Examples and Comparative Examples, the same things as in Example 1 will be omitted.

[Example 1]

In this embodiment, the multilayer film shown in Fig. 1 was formed by the following procedure.

[materials]

Polyethylene terephthalate (hereinafter referred to as PET) having an intrinsic viscosity of 0.66 was synthesized by a polycondensation reaction. The catalyst used in the reaction was antimony trioxide. The PET was dried until the water content became 50 ppm or less, and then melted in an extruder equipped with a heater set at 280 to 300 ° C. Then, the molten PET was discharged from a die portion onto a chill roll supplied with static electricity to obtain an amorphous film. Subsequently, this amorphous film was stretched 2.9 times in the longitudinal direction of the film, 4.0 times in the transverse direction, and biaxial stretching was completed to produce a base material 11 having a thickness of 150 탆. The refractive index eta 1 of the base material 11 thus obtained was 1.65.

[Adhesive layer]

Shaped substrate 11 having a width of 2 m and a length of 2000 m was fed at a feed rate of 70 m / min, and its surface was subjected to a corona discharge treatment under the condition of 730 J / m ² . Thereafter, the coating liquid A was applied to both surfaces of the substrate 11 by a bar coating method, and the coating liquid A was dried at a temperature of 180 DEG C for one minute to form the first adhesive layer 12. [ Then, the first adhesive layer 12 was subjected to corona discharge treatment under the condition of 730 J / m ² . Thereafter, a coating liquid B was coated on the upper surface of the first adhesive layer 12 by a bar coating method, and the coating liquid B was dried at a temperature of 165 DEG C for 1 minute to form a second adhesive layer 13. [ The application amounts of the application liquids A and B were 4.4 ml / m ² on each surface.

[Application liquid A]

The coating liquid A was prepared by mixing the following materials in an application amount of solid content.

Polyester 70.0 (mg / m ² )

Carbodiimide compound 14.0 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion (dispersion in which tin oxide fine particles are dispersed in water) 14.0 (mg / m ² )

[Application liquid B]

An application amount of solid content was mixed with each of the following materials to prepare coating liquid B.

Polyester 45.0 (mg / m ² )

Carbodiimide Compound 9.0 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 143.0 (mg / m ² )

A silica dispersion (dispersion in which silica fine particles are dispersed in water) 1.2 (mg / m ² )

Carnauba wax 3.0 (mg / m ² )

After drying, the thicknesses of the first adhesive layer 12 and the second adhesive layer 13 were measured at a magnification of 200,000 times using a transmission electron microscope (JEM2010, manufactured by JEOL Ltd.). As a result, the thickness d1 of the first adhesive layer 12 was 88 nm, and the thickness d2 of the second adhesive layer 13 was 86 nm. The refractive indexes of the first adhesive layer 12 and the second adhesive layer 13 measured by a method described later were 1.567 and 1.650, respectively.

[Measurement of Thickness of Adhesive Layer]

The thickness of the adhesive layer was measured as follows. First, the film to which the first and second adhesive layers 12 and 13 were applied was filled with epoxy and dried. Thereafter, the film embedded with epoxy was cut into a microtome until the thickness became 100 nm, and a sample piece was obtained for the purpose of using the cross section of the sample piece to measure the thickness of the adhesive layer. An image of this sample piece was photographed at a magnification of 200,000 times by the transmission electron microscope described above. The thickness of 10 points was measured at 20 nm intervals in the photographed images, and the average value of the measured thicknesses was obtained except for the maximum value and the minimum value.

[Measurement of refractive index of adhesive layer]

Using a refractive index meter (SPA-4000, manufactured by Sairon Technology, Inc.), the refractive index of a sample having a coating layer formed at wavelengths of 660 nm and 850 nm was measured by a prism coupler method. Next, the refractive index eta 2 of the first adhesive layer 12 and the refractive index eta 3 of the second adhesive layer 13 at a wavelength of 550 nm were calculated based on the measurement value of the refractive index at each wavelength and the following Celmaire equation . The Selmair equation is expressed as η ² -1 = Aλ ² / (λ ² -B). Here,? Is a measurement wavelength (nm),? Is a refractive index at a measurement wavelength, and A and B are constants. The wavelengths and the refractive indexes are substituted into the above equation to calculate constants A and B. Subsequently, a wavelength of 550 nm is substituted for the refractive indexes eta 2 of the first adhesive layer 12 and the refractive index eta 3 of the second adhesive layer 13 at a wavelength of 550 nm &Lt; / RTI &gt; The above-mentioned sample was prepared by applying a coating liquid on a commercially available silicon wafer so as to have a thickness within a range of 3 to 4 mu m after drying to form a coating layer, and then drying the coating layer at a temperature of 105 DEG C for 10 minutes.

[Hard coat layer]

To prepare a cyclohexanone dispersion containing 30 mass% of titanium oxide TTO-55B (product of ISHIHARA SANGYO KAISHA, LTD.). 20 parts by mass of TTO-55B dispersion, 20 parts by mass of dipentaerythritol hexaacrylate (DPHA, manufactured by NIPPON KAYAKU CO., LTD.) And 2 parts by mass of Irgacure 184 (manufactured by Chiba Specialty Chemicals Inc.) ) Was added thereto to prepare a coating liquid for a hard coat layer having a solid content of 8 mass% (hereinafter referred to as a hard coat layer coating liquid). The hard coat layer coating liquid was coated on one side of the adhesive layer to a thickness of about 35 mu m to form a coating layer. Thereafter, the coated layer was dried at a temperature of 80 DEG C for 1 minute. Then, the dried coating layer was irradiated with ultraviolet rays using a high-pressure mercury lamp to cure the resin, thereby forming a hard coat layer 14 having a thickness of 3 占 퐉. The amount of ultraviolet ray irradiated on the coating layer was 1000 mJ / cm ² . The refractive index? 4 of the hard coat layer 14 was measured in the same manner as the method of measuring the refractive index of the first layer 12. The measured value was 1.83.

[Antireflection layer]

TU2111 (product of JSR Corporation) was applied to the hard coat layer 14 and dried. Then, it was irradiated with ultraviolet rays. The amount of ultraviolet light irradiated on the coating layer was 1000 mJ / cm ² . As a result, a layer having a thickness of 0.1 mu m and a low refractive index was formed. The refractive index of this layer was 1.39. Since the refractive index of the hard coat layer 14 is as high as 1.83, the layer having a low refractive index functions as the antireflection layer 15.

[Example 2]

As shown in Table 1, in Example 2, the coating liquid A in Example 1 was replaced by the coating liquid C, and the coating liquid B in Example 1 was replaced by the coating liquid D, In the same manner as described above.

[Application liquid C]

The coating liquid C was prepared by mixing the respective materials as shown below.

· Polyurethane 52.0 (mg / m ² )

Carbodiimide compound 10.4 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 110.0 (mg / m ² )

[Application liquid D]

The coating liquid D was prepared by mixing the respective materials as shown below.

Polyurethane 47.0 (mg / m ² )

Carbodiimide compound 9.4 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

· Titanium oxide dispersion

(Dispersion liquid in which titanium oxide fine particles were dispersed in water) 66.0 (mg / m ² )

Silica dispersion 1.2 (mg / m ² )

Carnauba wax 3.0 (mg / m ² )

[Example 3]

As shown in Table 1, in Example 3, except that the coating liquid A in Example 1 was replaced with the coating liquid E, and the coating liquid B in Example 1 was replaced with the coating liquid F, 1.

[Coating solution E]

The coating liquid F was prepared by mixing the following materials with the application amount of the solid content.

· Acrylic resin 73.0 (mg / m ² )

Carbodiimide compound 14.6 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 14.0 (mg / m ² )

[Application liquid F]

The coating liquid F was prepared by mixing the following materials with the application amount of the solid content.

Polyester 58.0 (mg / m ² )

Carbodiimide compound 11.6 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 56.0 (mg / m ² )

Silica dispersion 1.2 (mg / m ² )

Carnauba wax 3.0 (mg / m ² )

[Comparative Example 1]

As shown in Table 1, in Comparative Example 1, the coating liquid C in Example 2 was replaced with the coating liquid D, and the coating liquid D in Example 2 was replaced with the coating liquid C, .

[Comparative Example 2]

As shown in Table 1, in Comparative Example 2, the coating liquid E in Example 3 was replaced with the coating liquid F, and the coating liquid F in Example 3 was replaced with the coating liquid E, The experiment was carried out in the same manner.

[Comparative Example 3]

As shown in Table 1, the experiment was carried out in the same manner as in Example 1 except that the coating liquid A in Example 1 was replaced with the coating liquid G and the second adhesive layer was not formed.

[Application liquid G]

The coating liquid G was prepared by mixing the following materials with the application amount of the solid content.

Polyurethane 43.2 (mg / m ² )

Carbodiimide compound 8.6 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 0.9 (mg / m ² )

· Titanium oxide dispersion 79.0 (mg / m ² )

Silica dispersion 1.1 (mg / m ² )

Carnauba wax 3.0 (mg / m ² )

The materials for the preparation of the coating liquids A to G are as follows.

Polyester: Z 561, GOO CHEMICAL CO., LTD. Product, solid content 25%

Carbodiimide compound: Nisshinbo Industries, Inc. The product, Carbodiright V-02-L2 (aqueous solution with 10% solids, carbodiimide 385)

Surfactant A: CHUKYO YUSHI CO., LTD. The product, Rapisol B-90 (aqueous solution with 1% solids, anionic)

Surfactant B: Sanyo Chemical Industries, Ltd. The product Naloacty HN-100 (aqueous solution with a solids content of 5%, nonionic)

Tin oxide dispersion: ISHIHARA SANGYO KAISHA, LTD. Product SN-38F (aqueous solution having a solid content of 17%, average diameter of fine particles of antimony doped with tin oxide: 30 nm)

Silica dispersion: NIPPON AEROSIL CO., LTD. The product, OX-50 (aqueous solution with a solids content of 10%),

Carnauba wax: CHUKYO YUSHI CO., LTD. The product Cellosol 524 (aqueous solution with 3% solids)

Polyurethane: UD-350, Mitsui Chemicals, Inc. Product, solid content 38%

Titanium oxide dispersion: ISHIHARA SANGYO KAISHA, LTD. TTO-W-5 (aqueous solution having a solid content of 30%, average particle diameter of fine particles of titanium oxide: 70 nm)

Acrylic resin: ET-410, Nihon Junyaku Co., Ltd. Product, solid content 30%

The multilayered films formed in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated for adhesion, optical properties, and other five items. Evaluation 1 shows the degree of adhesion between the base material 11 and the first adhesive layer 12. Evaluation 2 shows the degree of adhesion between the second adhesive layer 13 and the hard coat layer 14. Evaluation 3 shows the state of the coated surface of the multilayer film. Evaluation 4 shows whether rainbow unevenness occurred on the multilayer film. Evaluation 5 indicates fault tolerance. Details of each evaluation method are shown below.

[One. Adhesion between the base material and the first adhesive layer]

First, the coating liquid used for forming the first adhesive layer 12 in each of the examples and the comparative examples was applied to the surface of the substrate 11, and the thus obtained sample was immersed in distilled water at a temperature of 60 占 폚 for 16 hours. Then, after the immersion, the sample was taken out from the distilled water, and the water drops attached to the surface of the sample were lightly wiped off with a piece of paper (product name: Kimwipe S-200, manufactured by NIPPON PAPER CRECIA CO., LTD.). Thereafter, the surface of the sample was immediately scrubbed with a 0.1 R diamond needle using an internal scratch strength tester (product name: HEIDON-18, Shinto Scientific Co., LTd.). The scratched portion was observed with a microscope at a magnification of 100 times, and then the state of peeling of the first adhesive layer 12 was visually observed and judged based on the following criteria. Thus, the adhesive strength between the base material 11 and the first adhesive layer 12, that is, the degree of adhesion was evaluated in five steps. The load applied to the diamond needle was set to 200 g. In the following evaluation, if the product is rated A or B, its level is sufficient.

Class A: Not peeled.

Grade B: The peeled area is less than 30% of the total area scratched with diamond needles.

Grade C: The peeled area is between 30% and 70% of the total area scratched with diamond needles.

Class D: The peeled area is between 70% and 100% of the total area scratched with diamond needles.

Grade E: In addition to the areas scratched with diamond needles, the coated layer in the vicinity of the scratch area is also peeled off.

[2. Adhesion between the second adhesive layer and the hard coat layer]

The humidity of the multilayer film including the hard coat layer 14 was maintained for 24 hours under an atmosphere of a temperature of 25 占 폚 and 60% RH to obtain a sample. Then, using a non-wing razor, six scratches were made in each of its length and width directions to form 25 grids on the surface of the sample to be evaluated. Thereafter, a cellophane tape (No. 405, width 24 mm, manufactured by Nichiban Co., Ltd.) was attached thereto. A cellophane tape was rubbed on the surface of the scratched sample by rubbing the cellophane tape with the eraser, and then the cellophane tape was peeled in the direction of 90 degrees with respect to the horizontal surface. The number of peeled lattices was thereby obtained, and the adhesive strength between the second adhesive layer 13 and the hard coat layer 14, that is, the degree of adhesion was evaluated in five steps. When the lattice was partially peeled off, the partially peeled portion was added to the number of lattices. In the following evaluation, if the product is rated A or B, the level is sufficient. The width of each scratch was 3 mm in the length and width directions.

Class A: Not peeled

Class B: Number of stripped grids is less than 1

Class C: Number of peeled grids is 1 or more and less than 3

Class D: Number of stripped grids is 3 to less than 20

Class E: 20 or more stripped grids

[3. State of the coated surface of the multilayer film]

First, a first adhesive layer 12 and a second adhesive layer 13 were formed on the surface of the substrate 11 to obtain a sample. Then, the sample was placed on a disc with a black dozen cloth, and the coating layer was irradiated with fluorescent diffused light passing through the milky white acrylic sheet. Then, the light reflected thereon was visually observed, and the uneven coating was judged on the basis of the criteria described later, and the coated surface was evaluated in three steps. In the following evaluation, if the product is rated A or B, its level is sufficient.

Grade A: Unevenness of application was not visually observed in samples subjected to blackening treatment and samples not subjected to blackening treatment.

Grade B: Uneven application was observed visually in the sample subjected to the blackening treatment, but unevenness in application was not observed in the sample not subjected to the blackening treatment.

Grade C: Nonuniform coating was visually observed in the sample subjected to the blackening treatment and the sample not subjected to the blackening treatment.

In Evaluation 3, in order to prevent reflection of light on the back surface in judging by naked eyes, a predetermined portion of the sample surface was subjected to blackening treatment so that the light transmittance at a wavelength of 550 nm was adjusted to 1% or less. In the above-described blackening treatment, a magic marker (product name: art line, supplementary ink for oil based inks, KR-20 black, manufactured by Shachigata Inc.) was applied to the surface of the sample opposite to the surface to be observed. The surface was then dried.

[4. Whether rainbow unevenness occurs in the multilayered film]

First, the humidity of the thus obtained multilayer film (including the first and second adhesive layers 12 and 13, the hard coat layer 14 and the antireflection layer 15) was measured for 24 hours under an atmosphere of 25 DEG C and 60% RH A sample was prepared by adjusting. Then, the sample surface free from the coating layer 14 was rubbed with a sandpaper, and then the black magic marker used in evaluation 3 was applied to prevent reflection of light on the back surface. Thereafter, the sample was placed on a disk and irradiated with a 3-wavelength fluorescent lamp (product name: Nationl PALOOK fluorescent lamp FL20SS, EX-D / 18) at a distance of 30 cm from above to generate interference fringes (rainbow unevenness) The supramorphism was observed with the naked eye. The observed interference fringes were considered to be irregular irregularities and evaluated in five stages based on the following criteria. In the following evaluation, if the product is rated A, B, or C, its level is sufficient.

Grade A: Rainbow irregularities are not observed at all.

Grade B: Rainbow irregularities are rarely observed.

Grade C: Rainbow irregularities are slightly observed.

Class D: Rainbow unevenness is strongly observed.

Grade E: Rainbow unevenness is observed very strongly.

[5. Defect Resistance]

First, an adhesive layer was formed on the surface of the base material 11 to obtain a multilayer film. Using a continuous load-type scratch resistance tester (product name: TYPE-HEIDON-18, a detection needle of a 0.1R sapphire needle manufactured by Shinto Scientific Co., Ltd., scratching speed of 600 mm / min, weight of 200 g) A load at the time of occurrence of defects on the multilayer film was obtained.

Class A (excellent fault tolerance): load when defects occur ≥30g

Class B (no practical problems): 30 g> Load when defects occur ≥ 20 g

Grade C (with problems): 20 g> Load when defects occur ≥ 20 g

Class D (with problems): 10g> Load at the time of fault

The results of Examples and Comparative Examples are shown collectively in Table 1. In Table 1, "Ex" represents an embodiment, "Com" represents a comparative example, "Eva" represents an evaluation, "d1" represents a thickness of the first adhesive layer, "d2" Eta 1 represents the refractive index of the base layer, "eta 2" represents the refractive index of the first adhesive layer, "eta 3" represents the refractive index of the second adhesive layer, and & . &Quot; CLAL "means a coating liquid," SL "means a surface layer," SAAL "means a second adhesive layer, and" FAAL "means a first adhesive layer. "BM" means the description. Evaluation 1 and 2 relate to adhesion, evaluation 4 relates to irregularity, and evaluation 5 relates to defect resistance.

As shown in Table 1, each example showed excellent results as a product used in all evaluations. On the other hand, in Comparative Examples 1 and 2, irregular irregularities causing problems as products were observed. Further, in Comparative Example 3 having one adhesive layer, A was rated as an excellent result in the evaluation of iridescence. The refractive index of the adhesive layer was 1.74. In order to realize such a high refractive index, it is necessary to set the content of the metal oxide particles contained in the adhesive layer to be high. As a result, the grade of defect tolerance is D, which causes practical problems. Further, since the content of the metal oxide particles is high, the strength of the adhesive layer is reduced, and the adhesive strength of the hard coat layer is also reduced. Therefore, the rating in evaluation 2 was C.

Next, the present invention will be described in detail with reference to examples and comparative examples according to the second and third embodiments of the present invention.

[Example 11]

In the present embodiment, the multilayer film 20 shown in Fig. 2 was formed by the following procedure. First, the same multilayer film 10 as in Example 1 was formed. The first adhesive layer 16, the second adhesive layer 17 and the NIRA coat layer 18 were formed on the surface of the base material 11 of the multilayer film 10. [ Thus, a multilayer film 20 including a hard coat layer 14 and an antireflection layer 15 on one side of the substrate 11, and a NIRA coat layer 18 on the other side thereof was obtained.

The first and second adhesive layers 16 and 17 and the NIRA coat layer 18 were formed on the base material 11 of the multilayer film 10 as follows. First, as in Example 1, a roll-shaped multilayer film 10 having a width of 2 m and a length of 2000 m was formed. While carrying the multilayer film 10 at a feed rate of 70 m / min, the surface of the multilayer film 10 was subjected to corona discharge treatment under the condition of 730 J / m ² . Thereafter, the coating liquid K is coated on the surface of the base material 11 of the multilayer film 10 by a bar coating method and then the coating liquid K is dried at 180 DEG C for one minute to form the first adhesive layer 16 . Subsequently, the surface of the first adhesive layer 16 was subjected to a corona discharge treatment under the condition of 730 J / m ² . Thereafter, the coating liquid L was applied to the surface of the first adhesive layer 16 by a bar coating method, and the coating liquid L was dried at 165 DEG C for 1 minute to form a second adhesive layer 17. [ The application amounts of the coating solutions K and L were 4.4 ml / m ² on each surface.

[Application liquid K]

The coating liquid K was prepared by mixing the respective materials as shown below.

Polyester 55.0 (mg / m ² )

Carbodiimide compound 11.0 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 91.0 (mg / m ² )

[Application liquid L]

The coating liquid L was prepared by mixing each of the following materials with the application amount of the solid content.

· Acrylic resin 60.0 (mg / m ² )

Carbodiimide compound 12.0 (mg / m ² )

Surfactant A 0.5 (mg / m ² )

Surfactant B 1.0 (mg / m ² )

Tin oxide dispersion 65.0 (mg / m ² )

Silica dispersion 1.1 (mg / m ² )

Carnauba wax 3.0 (mg / m ² )

[NIRA coat layer]

3.1 parts by mass of IRG-022, 0.5 parts by mass of IR1 and 1.7 parts by mass of SIR-159 were dissolved in 100 parts by mass of methyl ethyl ketone (MEK) as a near infrared absorbing dye and a commercially available UV curable polymer (product name: Z7503, 880 parts by weight were mixed together and stirred to prepare a coating liquid for an NIRA coat layer (hereinafter referred to as NIRA coat layer coating liquid). First, the NIRA coat layer coating liquid was applied to the second adhesive layer 17 to a thickness of about 20 mu m, followed by drying at 70 DEG C for 2 minutes. Thereafter, ultraviolet rays were irradiated thereto to cure the NIRA coat layer coating liquid. The amount of irradiated ultraviolet ray was set to 500 mJ / cm ² . As a result, an NIRA-coated multilayered film 20 having a thickness of 9 mu m after drying was formed.

The humidity of the thus formed NIRA-coated multilayer film 20 was maintained at a temperature of 25 DEG C and an atmosphere of 60% RH for 24 hours to obtain a sample. The surface of the NIRA coat layer was then sufficiently rubbed with the sandpaper as a sample and then applied with the black magic marker used in Evaluation 3 to prevent reflection of light on the surface of the NIRA coat layer. Thereafter, the sample was placed on a circular plate so that the antireflection film side was exposed to the outside, and irradiated with a 3-wavelength fluorescent lamp (product name: National PALOOK fluorescent lamp FL20SS, EX-D / 18) while maintaining a distance of 30 cm from above, A pattern (irregularity of iridescence) was generated, and this interference pattern was visually observed. The observed interference fringes were considered to be irregular irregularities and evaluated in five steps based on the above criteria. Since the evaluation result was grade A, it is considered to be sufficient to prevent rainbow unevenness.

[Example 12]

In Example 12, an experiment was conducted in the same manner as in Example 11, except that the first adhesive layer and the second adhesive layer were replaced with a single-layer adhesive layer on the side of the hard coat layer of Example 11. [ The adhesive layer was prepared as in the case of Comparative Example 3 using the coating liquid G. [

[Comparative Example 11]

In Comparative Example 11, an experiment was conducted in the same manner as in Example 11 except that the first adhesive layer and the second adhesive layer on the side of the NIRA coat layer in Example 11 were replaced by the first adhesive layer only. The first adhesive layer was prepared as in Example 3 using the coating liquid E.

As shown in Table 1, in Examples 11 and 12, since the evaluation degree of iridescence was A, it is considered to be a level enough to prevent rainbow unevenness. On the other hand, in Comparative Example 11, since the evaluation degree for iridescence is D, it is considered to be inferior.

The antireflection film thus formed was placed on a part of a commercially available PDP (trade name: W37P-HR9000, Hitachi, Ltd.) from which an optical filter had been removed. Then, it was confirmed that the above-mentioned antireflection film prevented the occurrence of irregularity of iridescence and had excellent optical properties such as antireflection performance. Similarly, an antireflection film on which the NIRA coat layer is formed is provided on the above-mentioned PDP, and the antireflection film on which the NIRA coat layer is formed prevents occurrence of irregularity in the iridescence, Excellent.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the scope and nature of the present invention as set forth in the claims appended hereto.

The above objects and advantages of the present invention will become readily apparent to those skilled in the art upon reading the following detailed description with reference to the accompanying drawings,

1 is a schematic cross-sectional view of a multilayer film according to a first embodiment of the present invention;

2 is a cross-sectional view schematically showing a multilayer film according to a second embodiment of the present invention; Also

3 is a cross-sectional view schematically showing a multilayer film according to a third embodiment of the present invention.

Claims (12)

A substrate made of a polyester having a refractive index eta 1; A first adhesive layer having a refractive index eta 2 on the substrate; A second adhesive layer having a refractive index of eta 3 on the first adhesive layer; An optical multilayer film comprising a surface layer having a refractive index eta 4 on the second adhesive layer, Wherein the surface layer is a hard coat layer and the eta 1, eta 2, eta 3 and eta 4 satisfy the following expressions (1), (2) and (3) D2 (nm) as the thickness of the second adhesive layer and the above-mentioned? 3 satisfy the relationship of d1 (nm) as the thickness of the first adhesive layer and the above eta 2 at the visible light wavelength lambda in the range of 550 to 600 nm, (5). &Lt; / RTI &gt; (? ¹ /? 4) ^1/2占 0.95?? ² /? 3? (? ¹ /? 4) ^{1/2 1/2} 1.05 (One) η1 <η4 ... (2) η2 <η3 ... (3) -30? D1 - {? / (4 占? 2)}? 30 ... (4) -30? D2 - {? / (4 占? 3)}? 30 ... (5) delete The optical multilayer film according to claim 1, wherein the first adhesive layer and the second adhesive layer contain at least one of a polyester, a polyurethane, and an acrylic resin. The optical multilayer film according to claim 3, wherein the second adhesive layer contains fine particles containing at least 50 wt% of one of tin oxide, indium oxide, zirconium oxide, and titanium oxide. The optical multilayer film according to claim 4, wherein at least one of the first adhesive layer and the second adhesive layer contains a compound having a plurality of carbodiimide structures in the molecule. delete The optical multilayer film according to claim 1, wherein the polyester is polyethylene terephthalate and? 4 as a refractive index of the hard coat layer is in a range of 1.75 to 2.0. The optical multilayer film according to claim 7, wherein an antireflection layer is formed on the hard coat layer, and the refractive index of the antireflection layer is 1.50 or less. delete delete delete An image display apparatus characterized by comprising the optical multilayer film according to any one of claims 1, 3, 4, 5, and 7 to 8.

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