TWI551898B - An optical sheet, a transparent conductive laminate, and a touch panel - Google Patents

Description

Optical sheet, transparent conductive laminate, and touch panel

The present invention relates to an optical sheet, a transparent conductive laminate including the optical sheet, and a touch panel including the transparent conductive laminate.

The liquid crystal display module (LCD) has the characteristics of thinness, light weight, low power consumption, etc. Most of the above features use the liquid crystal display module as a flat panel display, and the use is expanding year by year, and can be used as a mobile phone or a personal digital assistant (PDA). Display devices for information such as personal computers and televisions. In recent years, various characteristics required for a liquid crystal display module are various depending on the application, and as a characteristic required for a liquid crystal display module, bright (high luminance), easy viewing (wide viewing angle), and energy saving can be cited. Chemical, thin and lightweight, and large screens.

In order to improve the ease of operation, rapidity, and the like of a person who views, there is a liquid crystal display module in which a touch panel is mounted as the liquid crystal display module. Further, the liquid crystal display module in which the touch panel is mounted generally has a structure in which a touch panel, a liquid crystal display element, various optical sheets, and a backlight are sequentially superposed from the front side to the back side.

As such a touch panel, there are touch panels such as a capacitive method, a resistive film method, and an electromagnetic induction method. As a capacitive method, there is a method in which electrodes are extended in a direction in which they cross each other, and when a finger or the like contacts the touch panel, capacitance between the electrodes changes, the change is detected, thereby detecting an input position; and being transparent An alternating current having the same phase and the same potential is applied to both ends of the conductive film, and a weak current is generated when the finger contacts or approaches to form a capacitance, the weak current is detected, thereby detecting the input position, and the like.

Further, in such a touch panel, a polarizing plate is disposed on the outermost surface of the touch panel, and a pair of retardation films (1/4 wave plate) are disposed on the front surface side and the back surface side of the touch panel, thereby enabling the liquid crystal panel. The emitted light is well transmitted and can effectively prevent reflection of external light. Further, in order to improve the performance of preventing such damage of the retardation film, etc., an optical sheet in which a hard coat layer is laminated on a retardation film has been proposed.

However, such an optical sheet has a problem of curling due to a difference in hardness between the retardation film and the hard coat layer. Further, in the case where curl is generated, there is a change in the phase difference of the retardation film, resulting in a problem that the desired birefringence cannot be maintained.

On the other hand, a technical solution has recently been proposed in which the occurrence of curling can be suppressed by making the hard coat layer a two-layer structure including the first hard coat layer (inner layer) and the second hard coat layer (outer layer) (refer to Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-71392. In the hard coat film described in the publication, a cured resin layer made of a mixture of a radical polymerizable resin and a cationically polymerizable resin is provided as a first hard coat layer on the surface of the base material layer, and the first The surface of the hard coat layer is provided with a second hard coat layer having a thickness substantially the same as that of the first hard coat layer, whereby it is possible to prevent the occurrence of curl and the prevention of cracking while maintaining the scratch resistance.

Further, as a hard coat film having a hard coat layer having a two-layer structure, there is also proposed a solution in which the pencil hardness of the first hard coat layer is smaller than that of the second hard coat layer, and the first hard coat layer The thickness is thicker than the thickness of the second hard coat layer (see Patent Document 2: JP-A-2007-219013). In the hard coat film described in the publication, a first hard coat layer made of a low-shrinkage urethane acrylate or the like and a high-hardness urethane acrylate are laminated by the same coating method. The second hard coat layer is formed, so the thickness of the second hard coat layer is substantially more than half of the thickness of the first hard coat layer.

However, the hard coat film of the aforementioned Patent Document 1 is due to the first hard coat layer and the second hard coat layer. The thickness of the coating is substantially the same, so the first hard coat layer is thin, resulting in insufficient hardness of the surface of the hard coat film. Further, if the hard coat film increases the thickness of the hard coat layer in order to obtain sufficient hardness, the second hard coat layer becomes too thick, and there is a problem that curling occurs.

Further, in the hard coat film of the aforementioned Patent Document 2, although the thickness of the second hard coat layer is thinner than the thickness of the first hard coat layer, the thickness of the second hard coat layer is more than half of the thickness of the first hard coat layer. Therefore, as a result, the surface of the hard coat film does not have sufficient hardness, and in addition, curling cannot be reliably prevented.

Prior art literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-71392

Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-219013

In view of such circumstances, an object of the present invention is to provide an optical sheet having excellent hardness and capable of effectively preventing curling and preventing a change in phase difference, a transparent conductive laminated body including the optical sheet, and including the transparent conductive Touch panel of a sexual laminate.

In order to solve the above problems, the present invention provides an optical sheet comprising: a retardation film containing a transparent polymer as a main component; a first hard coat layer formed on one side of the retardation film; and a second hard coat layer Forming on one surface side of the first hard coat layer, the pencil hardness of the second hard coat layer is 3H or more, the pencil hardness of the first hard coat layer is smaller than the pencil hardness of the second hard coat layer, and the second The thickness of the hard coat layer is 1 μm or more and 10 μm or less, and the thickness of the first hard coat layer is 4 times or more and 20 times or less the thickness of the second hard coat layer.

The optical sheet is provided with a first hard coat layer having a pencil hardness smaller than that of the second hard coat layer between the retardation film and the second hard coat layer. Therefore, the optical sheet can prevent curling due to the difference in hardness between the retardation film and the second hard coat layer, and by the first hard The coating layer and the second hard coat layer can effectively increase the hardness of one side of the retardation film. In particular, the thickness of the second hard coat layer of the optical sheet is within the foregoing range, and the thickness of the first hard coat layer is maintained at 4 times or more and 20 times or less the thickness of the second hard coat layer, whereby the aforementioned optical The sheet is well protected from curling due to the relatively high pencil hardness of the second hard coat layer. As a result, the optical sheet can effectively prevent the phase difference of the retardation film from being changed due to the occurrence of curl.

In the optical sheet, it is preferable that the pencil hardness of the first hard coat layer is F or more and 2H or less. Thereby, the hardness of the one side of the retardation film can be improved more effectively.

In the optical sheet, it is preferable that the thickness of the first hard coat layer is 20 μm or more and 100 μm or less. Thereby, it is possible to better prevent the occurrence of curl.

In the optical sheet, it is preferable that the transparent polymer is a polycarbonate resin, a cycloolefin resin or an acrylic resin. In the case where a resin having a relatively low hardness and a curling property such as a polycarbonate resin or a cycloolefin resin is used as a main component of the retardation film, the optical sheet can be prevented from being curled and can be effectively improved. The hardness of one side of the retardation film. By using a polycarbonate resin as a main component of the retardation film, the optical sheet can improve impact resistance. By using a cycloolefin-based resin as a main component of the retardation film, the optical sheet can effectively suppress a change in phase difference due to an external force such as direct sunlight and heat generated by the display. Further, by using an acrylic resin as a main component of the retardation film, the optical sheet can have excellent optical transparency and can transmit light very well.

In the above optical sheet, it is preferable that the main component of the first hard coat layer is an ultraviolet curable resin. Thereby, the ease of manufacture can be improved. Further, the optical sheet can prevent thermal expansion or thermal contraction due to application of heat to the retardation film, thereby improving dimensional stability.

In the above optical sheet, preferably, when the main component of the first hard coat layer is contained When there is an ultraviolet curable resin, the ultraviolet curable resin is a cationically polymerizable resin. Thereby, the adhesion property with the retardation film can be improved, and the adhesive force can be suppressed from changing with time. Further, by using a cationically polymerizable resin as a main component of the first hard coat layer, the optical sheet can prevent curling and can further improve dimensional stability.

In the above optical sheet, it is preferable that the main component of the first hard coat layer contains an ultraviolet curable resin and contains an ultraviolet ray-resistant agent. In general, when the main component of the first hard coat layer is an ultraviolet curable resin, and the first hard coat layer contains an ultraviolet ray-resistant agent, the curing speed of the first hard coat layer becomes slow, and productivity is lowered. However, since the thickness of the first hard coat layer is set to be relatively thick, the optical sheet can contain a sufficient amount of the ultraviolet resistant agent in the first hard coat layer even if the concentration of the ultraviolet resistant agent is controlled to a relatively low concentration. Therefore, even in the case where the first hard coat layer contains a sufficient amount of the ultraviolet resistant agent, the optical sheet can suppress a decrease in the curing speed of the first hard coat layer, thereby preventing a decrease in productivity.

In the above optical sheet, it is preferable that the retardation film is a 1/4 wavelength film or a 1/2 wavelength film. Thereby, the optical sheet can be applied to a touch panel or the like.

In the above optical sheet, it is preferable that the optical sheet further includes a high refractive index layer formed on the other surface side of the retardation film. Thereby, the refractive index of the other surface side of the retardation film can be improved.

In the optical sheet, it is preferable that the high refractive index layer has a refractive index of 1.6 or more and 2.3 or less. Therefore, when the high refractive index layer side of the optical sheet is laminated on a transparent conductive layer such as a touch panel, the refractive index of the high refractive index layer can be made close to the refractive index of the transparent conductive layer. As a result, the optical sheet can reduce the visibility of the electrode pattern formed on the transparent conductive layer.

Further, in order to solve the aforementioned problems, the present invention also provides a transparent electroconductive laminate comprising: the optical sheet described above; and a transparent conductive layer laminated on the foregoing The other side of the aforementioned high refractive index layer of the optical sheet.

Since the transparent electroconductive laminate includes the optical sheet described above, it is possible to prevent the optical sheet from being curled, and it is possible to effectively prevent the phase difference of the retardation film from being changed due to the occurrence of curl. Further, since the transparent electroconductive laminate includes the optical sheet described above, the hardness of one surface side of the retardation film can be effectively improved. Further, by bringing the refractive index of the high refractive index layer close to the refractive index of the transparent conductive layer, for example, bringing the refractive index of the high refractive index layer close to the refractive index of ITO of 2.1 to 2.2 (λ = 520 nm), the transparent conductive laminated body For use in, for example, a touch panel, the visibility of the electrode pattern formed on the transparent conductive layer can be reduced.

In the transparent conductive laminate, it is preferable that a difference between a refractive index of the high refractive index layer and a refractive index of the transparent conductive layer is 0.6 or less. Thereby, the visibility of the electrode pattern formed on the transparent conductive layer can be further reduced.

Further, in order to solve the aforementioned problems, the present invention also provides a touch panel comprising the aforementioned transparent electroconductive laminate.

Since the touch panel includes the optical sheet described above, it is possible to prevent the optical sheet from being curled, and it is possible to effectively prevent the phase difference of the retardation film from being changed due to the occurrence of curl. Further, since the touch panel includes the optical sheet described above, the hardness of one surface side of the retardation film can be effectively improved. Further, by bringing the refractive index of the high refractive index layer close to the refractive index of the transparent conductive layer, the touch panel can reduce the visibility of the electrode pattern formed on the transparent conductive layer.

In the present invention, the term "pencil hardness" means a value obtained from the pencil scratch value described in the test method specified in JIS K5600-5-4. Further, the so-called "thickness" means an average thickness measured in accordance with JIS K7130.

The "anti-UV agent" is an additive having a function of preventing photodegradation by ultraviolet rays, and is a concept including an ultraviolet absorber and an ultraviolet stabilizer.

As described above, the optical sheet of the present invention, the transparent conductive layer including the optical sheet The laminate and the touch panel including the transparent conductive laminate can improve the hardness of the optical sheet, and can effectively prevent curling, thereby preventing the phase difference from being changed.

1‧‧‧ optical film

2‧‧‧ phase difference film

3‧‧‧hard coating

4‧‧‧First hard coating

5‧‧‧Second hard coating

11‧‧‧Optical film

12‧‧‧High refractive index layer

21‧‧‧Transparent Conductive Laminates

22‧‧‧Transparent conductive layer

31‧‧‧ touch panel

32‧‧‧ glass substrate

33‧‧‧Adhesive layer

41‧‧‧ touch panel

42‧‧‧ dot spacers

43‧‧‧ Column spacers

44‧‧‧Transparent conductive film

45‧‧‧High refractive index layer

46‧‧‧ glass substrate

Fig. 1 is a schematic cross-sectional view showing an optical sheet according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view showing an optical sheet different from the optical sheet of Fig. 1.

3 is a schematic cross-sectional view showing a transparent electroconductive laminate according to an embodiment of the present invention.

4 is a schematic cross-sectional view showing a touch panel according to an embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing a touch panel different from the touch panel of FIG. 4. FIG.

First embodiment

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The optical sheet 1 of Fig. 1 includes a retardation film 2 and a hard coat layer 3.

Phase difference film 2

The retardation film 2 is transparent because it is capable of transmitting light, and is particularly colorless and transparent. The retardation film 2 contains a transparent polymer as a main component. The retardation film 2 is a 1/4 wavelength film.

The transparent polymer contained as the main component of the retardation film 2 is not particularly limited, and the transparent polymer contained as the main component of the retardation film 2 may, for example, be a polycarbonate resin or a polyarylate resin. , polyfluorene-based resin, polyimide-based resin, polyether oxime-based resin, polyethylene terephthalate resin, polyethylene naphthalate resin, cycloolefin resin, acrylic acid Resin, maleic imine resin, etc. Among them, the transparent polymer contained as the main component of the retardation film 2 is preferably a polycarbonate tree from the viewpoints of optical characteristics, hardness, and the like. The fat, the cycloolefin resin or the acrylic resin is preferably a polycarbonate resin.

The retardation film 2 may contain other optional components as long as the transparency and the desired strength are not impaired, and it is preferable to contain 90% by weight or more of a main component composed of a transparent polymer, and more preferably 98% by weight or more. A main component composed of a transparent polymer. Here, examples of the optional component include an ultraviolet absorber, a stabilizer, a lubricant, a processing aid, a plasticizer, an impact modifier, a phase difference reducing agent, a matting agent, an antibacterial agent, an antifungal agent, and the like. .

The polycarbonate resin forming the retardation film 2 is not particularly limited, and any of a linear polycarbonate resin or a branched polycarbonate resin can be used. Further, as the polycarbonate resin forming the retardation film 2, a polycarbonate resin composed of a linear polycarbonate resin and a branched polycarbonate resin can also be used.

The linear polycarbonate resin is a linear aromatic polycarbonate resin produced by a conventional phosgene method or a melting method, and is made of a carbonate component and a diphenol component. As a precursor for introducing a carbonate component, phosgene, diphenyl carbonate, etc. are mentioned. Further, as the bisphenol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-di can be exemplified. (4-hydroxyphenyl)cyclohexane, 1,1-bis(3,5-dimethylsulfonyl-4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)fluorene Alkane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclodecane, 1,1-bis(3,5-dimethyl-4-hydroxybenzene Base) cyclododecane, 4,4'-dihydroxydiphenyl ether, 4,4'-thiodiphenol, 4,4'-dihydroxy-3,3-dichlorodiphenyl ether and the like. These may be used singly or in combination of two or more. Such a linear polycarbonate resin can be produced, for example, by the method described in U.S. Patent No. 3,819,672.

The branched polycarbonate resin is a polycarbonate resin produced by using a branching agent, and examples of the branching agent include phloroglucinol, trimellitic acid, and 1,1,1-tris(4- Hydroxyphenyl)ethane, 1,1,2-tris(4-hydroxyphenyl)ethane, 1,1,2-tris(4-hydroxyl Phenyl)propane, 1,1,1-tris(4-hydroxyphenyl)methane, 1,1,1-tris(4-hydroxyphenyl)propane, 1,1,1-tris(2-methyl- 4-hydroxyphenyl)methane, 1,1,1-tris(2-methyl-4-hydroxyphenyl)ethane, 1,1,1-tris(3-methyl-4-hydroxyphenyl)methane 1,1,1-tris(3-methyl-4-hydroxyphenyl)ethane, 1,1,1-tris(3,5-dimethyl-4-hydroxyphenyl)methane, 1,1 , 1-tris(3,5-dimethyl-4-hydroxyphenyl)ethane, 1,1,1-tris(3-chloro-4-hydroxyphenyl)methane, 1,1,1-tri ( 3-chloro-4-hydroxyphenyl)ethane, 1,1,1-tris(3,5-dichloro-4-hydroxyphenyl)methane, 1,1,1-tris(3,5-dichloro 4-hydroxyphenyl)ethane, 1,1,1-tris(3-bromo-4-hydroxyphenyl)methane, 1,1,1-tris(3-bromo-4-hydroxyphenyl)ethane 1,1,1-tris(3,5-dibromo-4-hydroxyphenyl)methane, 1,1,1-tris(3,5-dibromo-4-hydroxyphenyl)ethane, 4, 4'-dihydroxy-2,5-dihydroxydiphenyl ether and the like.

For example, as disclosed in Japanese Laid-Open Patent Publication No. Hei 03-182524, such a branched polycarbonate resin can be obtained by agitating a polycarbonate obtained from an aromatic bisphenol, a branching agent, and phosgene. The ester oligomer, the aromatic bisphenol, and the blocking agent are reacted while stirring the reaction mixture to form a turbulent flow, and when the viscosity of the reaction mixture is increased, The aqueous alkali solution is added and the reaction mixture is formed into a laminar flow for reaction. In the polycarbonate resin, the branched polycarbonate resin containing the resin composition of the present invention in an amount of from 5% by weight to 80% by weight is preferably contained in an amount of from 10% by weight to 60% by weight. This is because when the branched polycarbonate resin is less than 5% by weight, there is a problem that the tensile viscosity is lowered and molding is difficult in extrusion molding; when it exceeds 80% by weight, the shear viscosity of the resin is increased. High, the problem of reduced formability.

The cycloolefin resin to form the retardation film 2 is not particularly limited as long as it is a resin having a monomer unit composed of a cyclic olefin (cycloolefin). The cycloolefin resin used in the retardation film 2 may be any of a cycloolefin polymer (COP) or a cyclic olefin copolymer (COC), and is preferably a cyclic olefin copolymer.

The cycloolefin copolymer refers to an amorphous cyclic olefin resin which is a copolymer of a cyclic olefin and an olefin such as ethylene. As the cyclic olefin, a polycyclic cyclic olefin and a monocyclic cyclic olefin are present. Examples of the polycyclic cyclic olefin include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidene norbornene, butylnorbornene, and dicyclopentane. Diene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, tetracyclododecene, methyltetracyclododecene, dimethyltetracyclododecene , tricyclopentadiene, tetracyclopentadiene, and the like. Further, examples of the monocyclic cyclic olefin include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctanetriene, and cyclododecatriene.

The acrylic resin forming the retardation film 2 is a resin having a skeleton derived from acrylic acid or methacrylic acid. The example of the acrylic resin is not particularly limited, and examples thereof include poly(meth)acrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, and methyl methacrylate-( a methyl acrylate copolymer, a methyl methacrylate-acrylate-(meth)acrylic acid copolymer, a methyl (meth) acrylate-styrene copolymer, a polymer having an alicyclic hydrocarbon group (for example, a methyl group) Methyl acrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, and the like. Among the above acrylic resins, a C1-6 alkyl poly(meth)acrylate such as poly(methyl) acrylate is preferable, and a methyl methacrylate resin is more preferable.

The pencil hardness of the retardation film 2 is not particularly limited. For example, in order to further increase the hardness after the hard coat layer is applied, the pencil hardness of the retardation film 2 is preferably as high as possible, and may be 8 B or more and 2 B. the following. Even if the pencil hardness of the retardation film 2 is within the above range, the optical sheet 1 can maintain the pencil hardness of the other surface side at a level of 2H or more and 6H or less by the first hard coat layer 4 and the second hard coat layer 5. .

The thickness of the retardation film 2 is not particularly limited, and is preferably, for example, 20 μ. m or more and 200 μm or less. The upper limit of the thickness of the retardation film 2 is more preferably 150 μm, and is preferably 100 μm. On the other hand, the lower limit of the thickness of the retardation film 2 is more preferably 30 μm, and most preferably 50 μm. When the thickness of the retardation film 2 exceeds the above upper limit value, the speed and productivity of the production line at the time of production are lowered, and in the case where the optical sheet 1 is used for a liquid crystal display device, there is a liquid crystal display device. The proposed thinning requirements are opposite to the problem. On the other hand, when the thickness of the retardation film 2 is less than the aforementioned lower limit value, there are problems such as a decrease in strength and rigidity and a decrease in bending performance.

The glass transition temperature of the retardation film 2 is not particularly limited, but is preferably, for example, 120 ° C or more and 180 ° C or less. The upper limit of the glass transition temperature of the retardation film 2 is more preferably 160 ° C, and particularly preferably 140 ° C. On the other hand, the lower limit of the glass transition temperature of the retardation film 2 is more preferably 140 ° C, and particularly preferably 160 ° C. When the glass transition temperature of the retardation film 2 exceeds the above upper limit value, there is a problem in that uneven stretching tends to occur during film stretching and it is difficult to thermoform. On the contrary, in the case where the glass transition temperature of the retardation film 2 is less than the aforementioned lower limit value, there is a problem that heat resistance is deteriorated.

The method for producing the retardation film 2 is not particularly limited, and the retardation film 2 can be produced by forming a film and stretching a composition containing a transparent polymer as a main component.

The film forming method described above is not particularly limited, and examples thereof include a conventional film forming method such as a solvent casting method, a melt extrusion method, and a calendering method.

Further, as a solvent used in a solvent casting method such as a casting method and a doctor blade method for extruding a solution from a die, dichloromethane, chloroform, dioxolane, toluene, dimethylformamide may be exemplified. An organic solvent such as N-methylpyrrolidone. The solution concentration is, for example, preferably 10% by weight or more, and more preferably 15% by weight or more.

On the other hand, the melt extrusion method has high productivity because no solvent is used. because This is preferably to produce the retardation film 2 by melt extrusion.

The production method of the melt extrusion method may be a method of preparing a composition by a solution mixing method, a melt mixing method, or the like, and then extruding the composition to form a film; and by combining The dry mixture of the material is directly melt-extruded to form a film, and the like.

The solution mixing method may, for example, be a method in which a transparent polymer and an optional additive added as needed are dissolved in a solvent, mixed uniformly, and filtered by a screening program as needed. The foreign matter is removed, and the solution is injected into the insoluble solvent (or poor solvent) of the transparent polymer to recover the composition, and further dried to obtain a composition (solution mixture) as a target.

The melt-mixing method may be a method in which a transparent polymer and an optional additive to be added as needed are mixed as needed, and then the composition is obtained by melt mixing (melting and kneading). The solution mixture method can obtain a composition having a small heat history, but a large amount of a solvent is used for the composition, and there is a problem that a solvent remains in the composition. The melt mixing method has no problem of a solvent and is economically advantageous, so a melt mixing method is preferred.

As a method of forming a film by direct melt extrusion of a dry mixture of a composition containing a transparent polymer as a main component, the following method can be exemplified: a V-type mixer, a Henschel mixer, and mechanochemistry are used. A premixing device such as a device is sufficiently mixed with a composition containing a transparent polymer as a main component, and then granulated by an extrusion granulator or a pelletizing machine as necessary, and extruded by a twin-screw type The mixture is melt-kneaded by a melt extruder such as a machine, and then the melt-kneaded mixture is extruded from a flat mold (T-die) to form a film by melting. Further, in the method of forming a film by directly melt-extruding the dry mixture, a part of each component may be pre-mixed, and the mixed mixture may be supplied to the remaining components independently. Melt extruder.

In order to obtain a uniform retardation film 2, a melt extruder having no vent method can be used as the melt extruder. Further, a melt extruder having an exhaust port capable of discharging moisture in the raw material and volatile gas generated from the melt-kneaded resin may be used. Preferably, a vacuum pump for efficiently discharging the generated moisture and volatile gas to the outside of the melt extruder is provided at the exhaust port. Further, a net for removing foreign matter or the like mixed in the extruded raw material may be placed in a region before the mold portion of the melt extruder to remove foreign matter. Examples of such a mesh include a metal mesh, a screen changer, a sintered metal plate (a disk screening program, etc.).

When the glass transition temperature of the composition is Tg, the resin temperature at the time of melt extrusion is preferably Tg or more, more preferably Tg + 50 ° C to Tg + 250 ° C, particularly preferably Tg + 80 ° C to Tg + 200 °C. The film may be continuously stretched at the same time as the film formation or immediately after the film formation, and the retardation film 2 may be a desired 1/4 wavelength film. Further, the film obtained by these film formation methods may be further stretched to form the retardation film 2 as a 1/4 wavelength film.

After the composition is formed into a film, the retardation film 2 can be obtained by uniaxial stretching. As the uniaxial stretching method, any method such as transverse uniaxial stretching by a tenter method, longitudinal uniaxial stretching between rolls, and calendering between rolls can be used. The stretching ratio can be usually carried out in the range of 1.01 to 5 times depending on the tensile properties and optical properties (for example, refractive index distribution, in-plane retardation value, thickness direction retardation value, Nz coefficient) of the film. The aforementioned stretching may be carried out in one stage or in multiple stages. Further, the temperature at the time of stretching is from Tg - 30 ° C to Tg + 50 ° C, more preferably from Tg - 30 ° C to Tg + 30 ° C. When the temperature at the time of stretching is within the above-described temperature range, the molecular motion of the polymer is moderate, the orientation relaxation due to stretching is less likely to occur, the orientation control is facilitated, and desired optical characteristics are easily obtained, which is preferable.

Hard coating 3

The hard coat layer 3 includes a first hard coat layer 4 and a second hard coat layer 5. The thickness of the hard coat layer 3 is not particularly limited, but is preferably 21 μm or more and 105 μm or less. The upper limit of the thickness of the hard coat layer 3 is more preferably 82 μm, particularly preferably 63 μm. On the other hand, the lower limit of the thickness of the hard coat layer 3 is more preferably 32 μm, particularly preferably 43 μm. In the case where the thickness of the hard coat layer 3 exceeds the above upper limit value, the effect of preventing curling is substantially not promoted, and there is a problem that it is contrary to the demand for thinning of the optical sheet 1 described above. On the contrary, in the case where the thickness of the hard coat layer 3 is less than the aforementioned lower limit value, there is a problem that curling cannot be effectively prevented.

First hard coat 4

The first hard coat layer 4 is formed on one side of the retardation film 2. The first hard coat layer 4 may be formed only of a resin, or may contain an additive such as an ultraviolet ray inhibitor. The main component constituting the first hard coat layer 4 is not particularly limited, and examples thereof include an active energy ray-curable resin or a resin formed of a reactive ruthenium compound. Examples of the active energy ray-curable resin include an ultraviolet curable resin, an electron beam curable resin, and a radiation curable resin. Further, examples of the reactive hydrazine compound include tetraethoxydecane. Among them, as the main component of the first hard coat layer 4, an ultraviolet curable resin is preferable. By using an ultraviolet curable resin as a main component of the first hard coat layer 4, the optical sheet 1 can improve ease of manufacture. In addition, by using the ultraviolet curable resin as the main component of the first hard coat layer 4, it is possible to prevent thermal expansion or thermal shrinkage due to application of heat to the retardation film 2 during production, and the like. Dimensional stability. Examples of the ultraviolet curable resin include a radical polymerizable resin and a cationically polymerizable resin.

As the ultraviolet-polymerizable compound which forms the ultraviolet curable resin, a monomer or oligomer which is cured by a reaction such as polymerization or crosslinking by ultraviolet light can be used.

Examples of the monomer include a radical polymerizable monomer and cationic polymerization. monomer. Further, examples of the oligomer include a radical polymerizable oligomer and a cationic polymerizable oligomer.

The radical polymerizable monomer may, for example, be methyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate or lauryl (meth)acrylate. Monofunctional (meth) acrylates such as isobornyl acrylate, dicyclopentenyl (meth) acrylate; dipropylene glycol di(meth)acrylate; 1,6-hexane di(meth)acrylate Alcohol ester, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, penta(methyl Various (meth) acrylates such as polyfunctional (meth) acrylate such as dipentaerythritol acrylate or dipentaerythritol hexa(meth)acrylate.

The cationically polymerizable monomer may, for example, be an alicyclic epoxide such as 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenylcarboxylic acid or bisphenol A. A glycidyl ether such as diglycidyl ether, a vinyl ether such as 4-hydroxybutyl vinyl ether or an oxetane such as 3-ethyl-3-hydroxymethyloxetane.

The radical polymerizable oligomer may, for example, be urethane (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, triazine (meth) acrylate or hydrazine ( Various (meth) acrylate oligomers such as methyl acrylate; polythiol oligomers such as trimethylolpropane tridecyl acetate and pentaerythritol tetradecyl acetate; unsaturated polyester oligomers Wait.

The cationically polymerizable oligomer may, for example, be a novolac epoxy resin oligomer or an aromatic vinyl ether resin oligomer.

In particular, the ultraviolet polymerizable compound which forms the ultraviolet curable resin for the first hard coat layer 4 is preferably a cationically polymerizable monomer or a cationically polymerizable oligomer. The optical sheet 1 uses an ultraviolet curable resin as a main component of the first hard coat layer 4, and by using a cationically polymerizable monomer or a cationically polymerizable oligomeric polymer As the ultraviolet ray-polymerizable compound which forms the ultraviolet curable resin, the adhesion of the retardation film 2 to the first hard coat layer 4 can be improved, and the change in the adhesive force with time can be suppressed. Further, according to this configuration, the optical sheet 1 can prevent the first hard coat layer 4 from being cured and shrunk, and the dimensional stability can be further improved.

Further, two or more of the foregoing monomers and oligomers may be used in combination depending on the desired properties and the like.

Further, as the ultraviolet ray-polymerizable compound which forms the ultraviolet curable resin for the first hard coat layer 4, a radical polymerizable compound having a low curing shrinkage is preferably used. The radical polymerizable compound may, for example, be a polymethacrylonitrile Lilo hydroxypropyl silsesquioxane having a molecular weight of 1,000 to 3,000. In addition, as the ultraviolet curable resin having the above-mentioned radical polymerizable compound, for example, a radical polymerizable resin exemplified in JP-A-2008-120845 can be used.

The polymerization initiator contained in the first hard coat layer 4 may be a benzophenone, a thioxanthone or a benzene when the ultraviolet polymerizable compound is a radical polymerizable monomer or oligomer. Compounds such as acetoin and acetophenone. In addition, when the ultraviolet-polymerizable compound is a cationically polymerizable monomer or oligomer, the polymerization initiator contained in the first hard coat layer 4 may be a metallocene or an aromatic oxime. A compound such as aromatic iodine.

The content of the polymerization initiator is not particularly limited, and is preferably 1% by weight or more and 10% by weight or less, and more preferably 3% by weight or more and 6% by weight or less based on the ultraviolet curable resin. When the content of the polymerization initiator exceeds the above upper limit, the degree of polymerization of the ultraviolet curable resin is lowered, and there is a problem that a desired hardness cannot be obtained. On the other hand, when the content of the polymerization initiator is less than the above lower limit value, there is a problem that the curing reaction cannot be sufficiently performed.

Further, in order to improve coatability, the first hard coat layer 4 may further contain a solvent. Make The solvent may, for example, be an aliphatic hydrocarbon such as hexane or octane; an aromatic hydrocarbon such as toluene or xylene; an alcohol such as ethanol, 1-propanol, isopropanol or 1-butanol; methyl ethyl ketone or methyl methoxide; Ketones such as butyl ketone; esters such as ethyl acetate, butyl acetate, isobutyl acetate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol An organic solvent such as a glycol ether such as diethyl ether or an esterified glycol ether such as ethylene glycol monomethyl ether acetate or propylene glycol monomethyl ether acetate. These organic solvents may be used singly or in combination of a plurality of them as needed. Further, it is preferable that the solvent is evaporated and dried in the manufacturing process of the first hard coat layer 4. Therefore, the boiling point of the solvent is preferably 60 ° C or more and 160 ° C or less. Further, the solvent has a saturated vapor pressure at 20 ° C of 0.1 kPa or more and 20 kPa or less. The type and content of the solvent can be appropriately adjusted depending on the main component of the retardation film 2, the main component of the first hard coat layer 4, the thickness, and the like.

The first hard coat layer 4 may also contain an ultraviolet resistant agent. The ultraviolet ray inhibitor contained in the first hard coat layer 4 may, for example, be an ultraviolet absorber or a UV stabilizer.

Examples of the ultraviolet absorber include a salicylic acid ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a cyanoacrylate ultraviolet absorber, and a triazine ultraviolet absorber. As the benzoxazinone-based ultraviolet absorber or the like, one type or two or more types selected from the above-mentioned ultraviolet absorbers can be used. Among them, from the viewpoint of dispersibility, a triazine-based ultraviolet absorber and a benzoxazinone-based ultraviolet absorber are preferable. Further, as the ultraviolet absorber, a polymer having an ultraviolet absorbing group in a molecular chain is preferably used. By using the polymer having an ultraviolet absorbing group in the molecular chain, deterioration of the ultraviolet absorbing function due to bleeding of the ultraviolet absorbing agent or the like can be prevented. Examples of the ultraviolet absorbing group include a benzotriazole group, a benzophenone group, a cyanoacrylate group, a triazine group, a salicylic acid group, and a benzylidenemalonate group. Among them, benzotriazolyl, benzophenone, and triazinyl are excellent.

As the ultraviolet stabilizer, for example, a hindered amine-based ultraviolet stabilizer having high stability against ultraviolet rays is preferably used. By including the ultraviolet stabilizer in the first hard coat layer 4, radicals generated by ultraviolet rays, active oxygen, and the like can be inerted, thereby improving stability against ultraviolet rays, weather resistance, and the like. Further, when the first hard coat layer 4 is used together with the ultraviolet absorber and the ultraviolet stabilizer, the photodegradation prevention performance against ultraviolet rays and the weather resistance can be greatly improved.

The content (weight ratio) of the main component of the first hard coat layer 4 as the anti-UV agent is not particularly limited, but is preferably 0.1% by weight or more and 10% by weight or less. The upper limit of the content of the ultraviolet ray inhibitor relative to the main component of the first hard coat layer 4 is more preferably 8% by weight, particularly preferably 5% by weight. On the other hand, the lower limit of the content of the ultraviolet ray-resistant agent relative to the main component of the first hard coat layer 4 is more preferably 1% by weight, particularly preferably 3% by weight. When the content of the main component of the first hard coat layer 4 of the optical sheet 1 exceeds the above upper limit, the durability of the first hard coat layer 4 may be lowered. On the contrary, in the case where the content of the main component of the ultraviolet ray resistant agent with respect to the first hard coat layer 4 of the optical sheet 1 is less than the aforementioned lower limit, there is a problem that the first hard coat layer 4 cannot effectively achieve the ultraviolet ray resistance function.

In the optical sheet 1 described above, it is preferable that the first hard coat layer 4 contains an ultraviolet curable resin as a main component and contains an ultraviolet ray-resistant agent. In general, when the main component of the first hard coat layer 4 is an ultraviolet curable resin and the first hard coat layer 4 contains an ultraviolet ray-resistant agent, the curing rate of the first hard coat layer 4 is slow and the productivity is lowered. However, since the thickness of the first hard coat layer 4 of the optical sheet 1 is set to be thick, the first hard coat layer 4 can be sufficiently charged even if the concentration of the ultraviolet resistant agent is suppressed to a small concentration. Anti-UV agent. Therefore, even when the first hard coat layer 4 contains a sufficient amount of the ultraviolet resistant agent, the optical sheet 1 can suppress a decrease in the curing speed of the first hard coat layer 4, thereby preventing a decrease in productivity. In addition, in the case where the optical sheet 1 is a polycarbonate resin as a main component of the retardation film 2, By allowing the first hard coat layer 4 to contain an ultraviolet ray-resistant agent, yellowing or the like of the retardation film 2 can be effectively prevented.

The pencil hardness of the first hard coat layer 4 is smaller than the pencil hardness of the second hard coat layer 5. The pencil hardness of the first hard coat layer 4 is not particularly limited as long as it is lower than the pencil hardness of the second hard coat layer 5, and is preferably F or more and 2H or less. When the pencil hardness of the first hard coat layer 4 exceeds the above upper limit value, the optical sheet 1 is likely to be curled due to the difference in hardness between the retardation film 2 and the first hard coat layer 4. On the contrary, in the case where the pencil hardness of the first hard coat layer 4 is less than the aforementioned lower limit value, there is a problem that the optical sheet 1 described above cannot obtain a desired hardness.

The thickness of the first hard coat layer 4 is 4 times or more and 20 times or less the thickness of the second hard coat layer 5. The upper limit of the thickness of the first hard coat layer 4 is more preferably 18 times the thickness of the second hard coat layer 5, and particularly preferably 16 times. Further, the lower limit of the thickness of the first hard coat layer 4 is more preferably 6 times the thickness of the second hard coat layer 5, and particularly preferably 8 times. In the case where the thickness of the first hard coat layer 4 exceeds the aforementioned upper limit, there is a problem that the effect of preventing curling cannot be further promoted. On the contrary, in the case where the thickness of the first hard coat layer 4 is smaller than the aforementioned lower limit, there is a problem that curling cannot be effectively prevented.

Further, the thickness of the first hard coat layer 4 is not particularly limited, but is preferably 20 μm or more and 100 μm or less. The upper limit of the thickness of the first hard coat layer 4 is more preferably 80 μm, particularly preferably 60 μm. On the other hand, the lower limit of the thickness of the first hard coat layer 4 is more preferably 30 μm, particularly preferably 40 μm. When the thickness of the first hard coat layer 4 exceeds the above upper limit value, there is a problem that the curling prevention effect cannot be further promoted, and the requirement for the thinning of the optical sheet 1 is also reversed. On the contrary, in the case where the thickness of the first hard coat layer 4 is smaller than the aforementioned lower limit value, there is a problem that curling cannot be effectively prevented.

The tensile modulus of elasticity of the first hard coat layer 4 is not particularly limited, but is preferably 1 GPa or more and 4 GPa or less. Further, as the stretching of the first hard coat layer 4 The upper limit of the modulus of elasticity is more preferably 3.5 GPa, and particularly preferably 3 GPa. On the other hand, the lower limit of the tensile modulus of elasticity of the first hard coat layer 4 is more preferably 1.5 GPa, and particularly preferably 2 GPa. In the case where the tensile modulus of the first hard coat layer 4 exceeds the above upper limit value, there is a problem that curling cannot be effectively prevented. On the other hand, when the tensile modulus of the first hard coat layer 4 is less than the above lower limit value, there is a problem that the optical sheet 1 is difficult to form a desired hardness. Further, the "tensile modulus" in the present invention is a value measured in accordance with JIS K7113.

Further, the value obtained by multiplying the tensile modulus of the first hard coat layer 4 by the third of the thickness is preferably 20 kPa ‧ mm ³ or more and 500 kPa ‧ mm ³ or less, more preferably 40 kPa ‧ mm ³ or more and 400 kPa ‧ mm ³ or less It is particularly preferably 60 kPa ‧ mm ³ or more and 300 kPa ‧ mm ³ or less. In the case where the value obtained by multiplying the tensile modulus of the first hard coat layer 4 by the cube of the thickness exceeds the above upper limit value, the rigidity of the first hard coat layer 4 becomes excessively large, and it is difficult to hold the optical sheet 1 It is a problem of a roll. On the contrary, in the case where the value obtained by multiplying the tensile modulus of the first hard coat layer 4 by the cube of the thickness is smaller than the aforementioned lower limit value, the first hard coat layer 4 is easily deformed and applied to the retardation film 2 The problem of the stress on the upper side becomes larger.

The arithmetic mean roughness (Ra) of the surface on the one surface side of the first hard coat layer 4 is not particularly limited, but is preferably 0.5 μm or more and 8 μm or less. The upper limit of the arithmetic mean roughness (Ra) of the surface on the one surface side of the first hard coat layer 4 is more preferably 7 μm, particularly preferably 6 μm. On the other hand, the lower limit of the arithmetic mean roughness (Ra) of the surface on the one surface side of the first hard coat layer 4 is more preferably 1 μm, and is preferably 2 μm. In the case where the arithmetic mean roughness (Ra) of the surface on one side of the first hard coat layer 4 exceeds the above upper limit value, there is a second hard coat layer 5 which is formed on the other surface side of the first hard coat layer 4. The problem of thickening of the thickness. On the other hand, when the arithmetic mean roughness (Ra) of the surface on the one surface side of the first hard coat layer 4 is smaller than the lower limit value described above, the surface area on the one side of the first hard coat layer 4 cannot be sufficiently increased, so that there is Second hard coat 5 The problem of reduced adhesion. On the other hand, in the case where the arithmetic mean roughness (Ra) of the one surface side surface of the first hard coat layer 4 is within the above range, the thickness of the second hard coat layer 5 can be maintained at an appropriate thickness, and can be effective. The adhesion of the first hard coat layer 4 to the second hard coat layer 5 is improved.

In addition, the ten-point average roughness (Rz) of the surface on the one surface side of the first hard coat layer 4 is not particularly limited, but is preferably 0.5 μm or more and 10 μm or less. The upper limit of the ten point average roughness (Rz) of the surface on the one side of the first hard coat layer 4 is more preferably 9 μm, particularly preferably 8 μm. On the other hand, the lower limit of the ten point average roughness (Rz) of the surface on the one surface side of the first hard coat layer 4 is more preferably 1 μm, particularly preferably 2 μm. When the ten-point average roughness (Rz) of the surface on the one surface side of the first hard coat layer 4 exceeds the above upper limit, there is a problem that the thickness of the second hard coat layer 5 is increased. On the other hand, when the point average roughness (Rz) of the surface 10 on the one surface side of the first hard coat layer 4 is smaller than the aforementioned lower limit, the surface area of the one surface side of the first hard coat layer 4 is not sufficiently increased, so The problem that the adhesion of the second hard coat layer 5 is lowered. In addition, "arithmetic mean roughness (Ra)" and "ten point average roughness (RZ)" are values obtained according to JIS B0601-2001.

The method for producing the first hard coat layer 4 is not particularly limited, and the first hard coat layer 4 can be produced by applying an active energy ray-curable resin to one surface of the retardation film 2, drying the resin, and irradiating the active energy ray. The method of applying the active energy ray-curable resin is not particularly limited as long as it can uniformly apply the active energy ray-curable resin on one surface of the retardation film 2, and examples thereof include a spin coating method, a spray coating method, and a slope method. Various methods such as a flow coating method, a dipping method, a bar coating method, a roll coating method, and a screen printing method. Further, in the production of the first hard coat layer 4, as the pretreatment, a surface modification treatment such as plasma treatment may be performed under an inert gas atmosphere such as argon gas or nitrogen gas as needed. Further, an undercoat layer may be laminated on one surface of the retardation film 2, and the first hard coat layer 4 is laminated via the undercoat layer.

Second hard coat 5

The second hard coat layer 5 is formed on one side of the first hard coat layer 4. The material forming the second hard coat layer 5 is not particularly limited. The second hard coat layer 5 may be formed only of a resin, or may contain an additive such as cerium oxide fine particles therein.

The resin forming the second hard coat layer 5 may, for example, be a thermosetting resin, an active energy ray-curable resin or the like.

For example, a polymerizable monomer or a polymerizable oligomer can be applied by coating a coating composition containing a polymerizable monomer or a polymerizable oligomer of an active energy ray-curable resin on one surface of the first hard coat layer 4. A crosslinking reaction and/or a polymerization reaction occurs, thereby forming the second hard coat layer 5.

The functional group of the active energy ray-curable polymerizable monomer or polymerizable oligomer is preferably an ultraviolet ray, an electron beam or a radiation polymerizable functional group, and is preferably an ultraviolet ray-polymerizable functional group. Examples of the ultraviolet polymerizable functional group include an ethylenically unsaturated polymerizable functional group such as a (meth)acryl fluorenyl group, a vinyl group, a styryl group, and an allyl group.

The coating composition is not particularly limited, but is preferably a coating composition containing an acrylic monomer or a urethane acrylate oligomer as a main component. The hardness of the second hard coat layer 5 can be improved by forming the second hard coat layer 5 from the composition containing the above-mentioned monomer or oligomer as a main component. Among them, it is excellent to form the second hard coat layer 5 from a composition containing both a urethane acrylate and a (meth)acrylic compound.

The total content of the urethane acrylate and the (meth)acrylic compound forming the second hard coat layer 5 is preferably 45% by weight or more and 99% by weight or less, particularly preferably 50% by weight or more and 95% by weight or less, which is excellent. It is 60% by weight or more and 90% by weight or less. If the total content of the urethane acrylate and the (meth)acrylic compound forming the second hard coat layer 5 exceeds the aforementioned upper limit, the start of photopolymerization becomes slow This leads to a problem of reduced productivity. Further, when the total content of the urethane acrylate and the (meth)acrylic compound forming the second hard coat layer 5 is less than the aforementioned lower limit, there is a problem that the flexibility, the abrasion resistance, the scratch resistance, and the like are lowered. On the other hand, if the total content of the urethane acrylate and the (meth)acrylic compound forming the second hard coat layer 5 is within the above range, the productivity can be improved, and the appropriate flexibility and abrasion resistance can be well maintained. Damage and scratch resistance.

The urethane acrylate described above is not particularly limited and may be either a monomer or an oligomer. Further, the number of the functional groups of the urethane acrylate is not particularly limited, and may be a monofunctional group or a polyfunctional group, preferably a bifunctional group or more and a hexafunctional group or less, and particularly preferably a bifunctional group or more and a trifunctional group or less. . By making the number of functional groups of the urethane acrylate within the above range, the balance between the hardness and the elongation of the second hard coat layer 5 can be well maintained. The urethane acrylate may be used singly or in combination of two or more.

The glass transition temperature of the resin formed of urethane acrylate is not particularly limited, but is preferably 40° C. or higher and 100° C. or lower, and particularly preferably 40° C. or higher and 80° C. or lower. By setting the glass transition temperature of the resin formed of urethane acrylate to the above range, the hardness and durability of the second hard coat layer 5 at normal temperature can be improved.

The content of the urethane acrylate forming the second hard coat layer 5 is not particularly limited, but is preferably 10% by weight or more and 90% by weight or less, particularly preferably 15% by weight or more and 85% by weight or less, and most preferably 20% by weight. The weight% or more is 80% by weight or less. When the content of the urethane acrylate forming the second hard coat layer 5 exceeds the above upper limit, there is a problem that abrasion resistance and coating film hardness are lowered. Further, if the content of the urethane acrylate forming the second hard coat layer 5 is less than the aforementioned lower limit, the flexibility is lowered and the possibility of occurrence of cracks is increased. On the other hand, if the content of the urethane acrylate forming the second hard coat layer 5 is within the above range, it can be well maintained. It is resistant to abrasion and film hardness, and is capable of maintaining proper flexibility and suppressing generation of cracks.

The (meth)acrylic compound is not particularly limited, and may be either a monomer or an oligomer. The number of the functional groups of the (meth)acrylic compound is not particularly limited, and may be a monofunctional group or a polyfunctional group. Further, the second hard coat layer 5 can improve durability by using a (meth)acrylic compound having a trifunctional group or more. Further, the aforementioned (meth)acrylic compound may be a molecular structure having a polar group or a molecular structure having a low polarity. The (meth)acrylic compound may be used singly or in combination of two or more.

Examples of the polar group of the (meth)acrylic compound include a hydroxyl group, a carboxyl group, an amino group, a decylamino group and the like.

Examples of the hydroxyl group-containing (meth)acrylic compound include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. Base) 2-hydroxy-3-phenoxypropyl acrylate, 2-(meth) propylene methoxyethyl 2-hydroxypropyl phthalate, glycerol mono(meth) acrylate, ( A hydroxyl group-containing ester of (meth)acrylic acid such as 3-hydroxypropyl methacrylate, 3-hydroxybutyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate.

Examples of the (meth)acrylic compound containing a carboxyl group include, in addition to the ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid, 2-(A) Acryloxyethyl succinate, 2-(meth) propylene oxirane ethyl phthalate, 2-(methyl) propylene methoxyethyl hexahydroterephthalate Wait.

The (meth)acrylic compound containing an amino group may, for example, be monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate or monomethylaminopropyl (meth)acrylate. , (meth)acrylic acid monoethylaminopropyl ester, etc. (methyl) Monoalkyl acrylate or the like.

Examples of the (meth)acrylic compound containing a guanamine group include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, and the like. Acrylamides and the like.

Further, as the (meth)acrylic compound having a low polar molecular structure, a (meth) acrylate cyclic ester or an alkyl (meth)acrylate may be mentioned.

The (meth) acrylate cyclic ester may, for example, be cyclohexyl (meth)acrylate, isobornyl (meth)acrylate or dicyclopentenyloxyethyl (meth)acrylate, ( Dicyclopentadienyl (meth)acrylate, tricyclodecenyl (meth)acrylate, norbornene (meth)acrylate, and the like.

The alkyl (meth)acrylate may, for example, be lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate or benzyl (meth)acrylate. , octadecyl (meth)acrylate, butyl (meth)acrylate, 1,6-hexanediol acrylate.

The content of the (meth)acrylic compound forming the second hard coat layer 5 is not particularly limited, but is preferably 5% by weight or more and 85% by weight or less, particularly preferably 10% by weight or more and 80% by weight or less. It is 15% by weight or more and 75% by weight or less. When the content of the (meth)acrylic compound forming the second hard coat layer 5 exceeds the above upper limit, the possibility of occurrence of cracks during molding increases. Further, when the content of the (meth)acrylic compound forming the second hard coat layer 5 is less than the aforementioned lower limit, there is a problem that abrasion resistance and coating film hardness are lowered. On the other hand, if the content of the (meth)acrylic compound forming the second hard coat layer 5 is within the above range, proper wear resistance and film hardness can be well maintained, and appropriate softness can be maintained. Sex and can inhibit the formation of cracks.

The above polymerization initiator may, for example, be benzophenone, benzoin, tetramethylmistone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether or benzophenone. Marriage Propyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzoin dimethyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-? Polinylacetone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis(cyclopentadienyl)- Bis(2,6-difluoro-3-(pyrrol-1-yl)titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone-1, 2, 4,6-trimethylbenzimidyldiphenylphosphine oxide, etc. Further, the above compounds may be used singly or in combination of a plurality of them.

The pencil hardness of the second hard coat layer 5 is 3H or more. The pencil hardness of the second hard coat layer 5 is more preferably 4H or more, and particularly preferably 5H or more. When the pencil hardness of the second hard coat layer 5 is less than the aforementioned lower limit value, there is a problem that it is difficult to form the optical sheet 1 into a desired hardness.

The thickness of the second hard coat layer 5 is 1 μm or more and 10 μm or less. The upper limit of the thickness of the second hard coat layer 5 is more preferably 8 μm, particularly preferably 6 μm. On the other hand, the lower limit of the thickness of the second hard coat layer 5 is more preferably 2 μm, particularly preferably 3 μm. When the thickness of the second hard coat layer 5 exceeds the above upper limit value, curling cannot be effectively prevented, and the requirements for the thinning of the optical sheet 1 described above are also reversed. On the other hand, when the thickness of the second hard coat layer 5 is less than the aforementioned lower limit value, there is a problem that it is difficult to form the optical sheet 1 into a desired hardness.

The tensile modulus of elasticity of the second hard coat layer 5 is not particularly limited, but is preferably 1.5 GPa or more and 6 GPa or less. Further, the upper limit of the tensile modulus of the hard coat layer 5 is more preferably 5.5 GPa, and particularly preferably 5 GPa. On the other hand, the lower limit of the tensile modulus of the second hard coat layer 5 is more preferably 2 GPa, and particularly preferably 2.5 GPa. In the case where the tensile modulus of the second hard coat layer 5 exceeds the above upper limit value, there is a problem that it is difficult to effectively prevent curling. On the other hand, when the tensile modulus of the second hard coat layer 5 is less than the aforementioned lower limit value, it is difficult to form the optical sheet 1 into a desired hardness. Degree problem.

Further, the ratio of the tensile modulus of elasticity of the second hard coat layer 5 to the tensile modulus of the first hard coat layer 4 is not particularly limited, but is preferably 1.5 or more and 4 or less. The upper limit of the ratio of the tensile modulus of the second hard coat layer 5 to the tensile modulus of the first hard coat layer 4 is more preferably 3.5, and particularly preferably 3. On the other hand, the lower limit of the ratio of the tensile modulus of the second hard coat layer 5 to the tensile modulus of the first hard coat layer 4 is preferably 1.7, and particularly preferably 2. In the case where the ratio of the tensile modulus of elasticity of the second hard coat layer 5 to the tensile modulus of the first hard coat layer 4 exceeds the above upper limit, there is a problem that it is difficult to effectively prevent curling. On the other hand, in the case where the ratio of the tensile modulus of the second hard coat layer 5 to the tensile modulus of the first hard coat layer 4 is less than the aforementioned lower limit, there is a problem that the hardness of the optical sheet 1 cannot be effectively improved.

The method for producing the second hard coat layer 5 is not particularly limited, and it can be produced by the same method as the method of producing the first hard coat layer 4.

Optical sheet 1

The haze of the optical sheet 1 is not particularly limited, but is preferably 2% or less, more preferably 1% or less, and particularly preferably 0.5% or less. When the haze of the optical sheet 1 exceeds the above upper limit value, there is a problem that the visibility of the image is lowered and the sharpness of the displayed image is lowered.

The external haze of the optical sheet 1 is preferably 1.0% or less, particularly preferably 0.5% or less, and the external haze is the difference between the haze (Ha) of the film in the air and the haze (Hw) of the film in the water. (Ha-Hw). When the external haze of the optical sheet 1 exceeds the above upper limit, there is a problem that the unevenness of the surface becomes relatively large and the phase difference accuracy is lowered.

The visible light transmittance of the optical sheet 1 is preferably 87% or more, and particularly preferably 90% or more, although it is not particularly limited. In the case where the visible light transmittance of the optical sheet 1 is smaller than the lower limit of the aforementioned range, there is a possibility that the light is not sufficiently made. Through, resulting in a problem of reduced visibility.

The optical sheet 1 is provided between the retardation film 2 and the second hard coat layer 5 with a first hard coat layer 4 having a pencil hardness smaller than that of the second hard coat layer 5. Therefore, the optical sheet 1 described above can prevent curl caused by the difference in hardness between the retardation film 2 and the second hard coat layer 5, and can effectively increase the phase difference by the first hard coat layer 4 and the second hard coat layer 5. The hardness of one side of the film 2. In particular, by making the thickness of the second hard coat layer 5 of the optical sheet 1 within the aforementioned range, and maintaining the thickness of the first hard coat layer 4 in the foregoing range with respect to the thickness of the second hard coat layer 5, The curl due to the higher pencil hardness of the second hard coat layer 5 can be well suppressed by the first hard coat layer 4. Further, the first hard coat layer 4 of the aforementioned optical sheet 1 is thick. Therefore, the optical sheet 1 can effectively achieve a buffering function for preventing curling by the first hard coat layer 4, and can effectively improve the hardness of one surface side of the optical sheet 1. As a result, even if the second hard coat layer 5 of the optical sheet 1 is formed thin, it can complement the formed first hard coat layer 4 to obtain a desired hardness. The optical sheet 1 can prevent the occurrence of curling, and can effectively prevent the phase difference of the retardation film 2 from being changed due to the occurrence of curl.

In the optical sheet 1 , when a resin having a relatively low hardness and a curling property such as a polycarbonate resin or a cycloolefin resin is used as a main component of the retardation film 2, curling can be prevented and effective. The hardness of one surface side of the retardation film 2 is increased. By using a polycarbonate resin as a main component of the retardation film 2, the optical sheet 1 can improve impact resistance. By using a cycloolefin-based resin as a main component of the retardation film 2, the optical sheet 1 can effectively suppress a change in phase difference caused by an external force such as direct sunlight and display heat. Further, by using an acrylic resin as a main component of the retardation film 2, the optical sheet 1 can have excellent optical transparency and can transmit light very well.

Since the retardation film 2 is a 1/4 wavelength film, the aforementioned optical sheet 1 is suitable for use in touch Touch the panel and so on.

Second embodiment Optical sheet 11

The optical sheet 11 of FIG. 2 includes a retardation film 2, a hard coat layer 3, and a high refractive index layer 12. Since the retardation film 2 and the hard coat layer 3 in the present embodiment are the same as the retardation film 2 and the hard coat layer 3 of the optical sheet 1 of Fig. 1, they are given the same reference numerals, and their instruction of.

High refractive index layer 12

The high refractive index layer 12 is formed on the other surface of the retardation film 2. The main component of the high refractive index layer 12 is not particularly limited, and examples thereof include a thermosetting resin, a thermoplastic resin, and an active energy ray-curable resin. Examples of the thermosetting resin include phenol resin, melamine resin, urethane resin, urea resin, diallyl phthalate resin, guanamine resin, unsaturated polyester resin, amino alkyd resin, and melamine. - a urea co-condensation resin, an anthracene resin, a polyoxyalkylene resin, or the like. Further, in the above-mentioned resin, a crosslinking agent, a polymerization initiator, a polymerization accelerator, a solvent, a viscosity adjuster, or the like may be added as needed.

Further, the high refractive index layer 12 may be formed by applying a coating composition obtained by adding ultrafine particles having a high refractive index to the binder resin. Examples of the ultrafine particles include inorganic materials such as ZnO, TiO ₂ , CeO ₂ , SnO ₂ , ITO, Cs _0.33 WO ₃ , Al ₂ O ₃ , La ₂ O ₃ , ZrO ₂ , and Y ₂ O ₃ . On the other hand, the binder resin may be the same as the resin forming the second hard coat layer 5. After the above-mentioned inorganic material is ultrafinely granulated, the ultrafine particles are dispersed in a binder resin, and after being diluted with a solvent, by a roll coating method, a spin coating method, a dip coating method, a spray coating method, a bar coating method, A conventional coating method such as a doctor blade method, a die coating method, an inkjet coating method, or a gravure coating method forms the high refractive index layer 12.

The average particle diameter of the above ultrafine particles is not particularly limited, but is not particularly limited. It is preferably 1 nm or more and 100 nm or less. The upper limit of the average particle diameter of the above-mentioned ultrafine particles is more preferably 80 nm, and particularly preferably 60 nm. On the other hand, the lower limit of the average particle diameter of the above-mentioned ultrafine particles is more preferably 5 nm, and particularly preferably 10 nm. When the average particle diameter of the ultrafine particles exceeds the above upper limit value, there is a problem that the transparency of the high refractive index layer 12 is lowered. On the other hand, when the average particle diameter of the above-mentioned ultrafine particles is less than the aforementioned lower limit value, there is a problem that the dispersibility of the ultrafine particles is lowered.

The content of the ultrafine particles with respect to the binder is not particularly limited, but may be, for example, 10% by weight or more and 60% by weight or less.

The refractive index of the high refractive index layer 12 is not particularly limited, but is preferably 1.6 or more and 2.3 or less. The upper limit of the refractive index of the high refractive index layer 12 is more preferably 2.25, and particularly preferably 2.2. On the other hand, the lower limit of the refractive index of the high refractive index layer 12 is more preferably 1.7, particularly preferably 1.75. When the refractive index of the high refractive index layer 12 is out of the above range, when the high refractive index layer 12 of the optical sheet 11 is laminated with a transparent conductive layer such as a touch panel, the refractive index and transparency of the high refractive index layer 12 are transparent. The difference in refractive index of the conductive layer becomes large, and there is a problem that the visibility of the electrode pattern formed on the transparent conductive layer increases.

The pencil hardness of the high refractive index layer 12 is not particularly limited, but is preferably F or more and 2H or less. The upper limit of the pencil hardness of the high refractive index layer 12 is more preferably H. On the other hand, the lower limit of the pencil hardness of the high refractive index layer 12 is more preferably HB. Further, the thickness of the high refractive index layer 12 is not particularly limited, but is preferably 50 nm or more and 10 μm or less. The upper limit of the thickness of the high refractive index layer 12 is more preferably 7 μm, particularly preferably 5 μm. On the other hand, the lower limit of the thickness of the high refractive index layer 12 is more preferably 100 nm, and particularly preferably 200 nm. In the case where the pencil hardness and the thickness of the high refractive index layer 12 exceed the respective upper limit values, respectively, the possibility of occurrence of curling becomes high, and the requirement for thinning of the optical sheet 11 is also reversed. In contrast, the pencil hardness and thickness of the high refractive index layer 12 are respectively smaller than the respective lower limit values of the respective In the case, there is a problem that the hardness of the other surface side of the retardation film 2 cannot be improved satisfactorily. On the other hand, when the pencil hardness and the thickness of the high refractive index layer 12 are within the respective ranges described above, the hardness of the other surface side of the retardation film 2 can be improved and curling can be prevented, and the aforementioned The optical sheet 11 is made thinner.

Since the optical sheet 11 includes the high refractive index layer 12 formed on the other surface side of the retardation film 2, the refractive index of the other surface side of the retardation film 2 can be improved. Further, the haze, the external haze, and the visible light transmittance of the optical sheet 11 are the same as those of the optical sheet 1.

Third embodiment Transparent conductive laminate 21

The transparent electroconductive laminate 21 of FIG. 3 includes an optical sheet 11 and a transparent conductive layer 22. The optical sheet 11 in the present embodiment is the same as the optical sheet 11 in Fig. 2, and therefore the same reference numerals are given thereto, and the description thereof is omitted.

Transparent conductive layer 22

The transparent conductive layer 22 is laminated on the other surface of the high refractive index layer I2. The material for forming the transparent conductive layer 22 is not particularly limited as long as it is a conductive material having transparency and conductivity, and examples thereof include an inorganic metal and an organic conductive polymer. The inorganic metal may, for example, be gold, silver, copper, platinum, nickel, tin oxide or indium tin oxide (ITO). The organic conductive polymer may, for example, be an organic conductive composition such as polyaniline, polythiophene, polypyrrole or polyquinoxaline. Among them, ITO or polythiophene-based materials having excellent optical properties, appearance, and conductivity are preferred.

The method of forming the material for forming the transparent conductive layer 22 on the high refractive index layer 12 is not particularly limited, and may be, for example, a roll coating method, a spin coating method, a dip coating method, a spray coating method, a bar coating method, or a scraping method. A conventional coating method such as a coating method, a die coating method, an inkjet coating method, or a gravure coating method. Further, when the material for forming the transparent conductive layer 22 is applied, in order to improve the adhesion to the high refractive index layer 12, it is also possible to The high refractive index layer 12 is subjected to pretreatment such as corona discharge treatment.

The curing method of the material for forming the transparent conductive layer 22 can be performed by, for example, a high-pressure mercury lamp, a halogen lamp, a xenon lamp, a nitrogen laser, an electron beam acceleration device, an active energy ray source such as a radioactive element, or the like. Further, the irradiation amount of the active energy ray is preferably 50 mJ/cm ² or more and 5000 mJ/cm ² or less in terms of the integrated light amount at a wavelength of 365 nm of ultraviolet rays. When the irradiation amount exceeds the above upper limit value, there is a problem that the active energy ray-curable resin is colored. On the other hand, when the irradiation amount is less than the aforementioned lower limit value, there is a problem that the curing is insufficient.

Further, the transparent conductive layer 22 may be formed by a dry method such as a sputtering method. As a method of forming the transparent conductive layer 22, a method of forming the transparent conductive layer 22 by a sputtering method is preferred from the viewpoint of adhesion to the high refractive index layer 12 and thickness reduction.

The thickness of the transparent conductive layer 22 when formed by the sputtering method is not particularly limited, but is preferably 50 Å or more and 2000 Å or less. The upper limit of the thickness of the transparent conductive layer 22 when formed by the above sputtering method is more preferably 1000 Å, and particularly preferably 500 Å. On the other hand, the lower limit of the thickness of the transparent conductive layer 22 when formed by the above sputtering method is more preferably 70 Å, and particularly preferably 90 Å. When the thickness of the transparent conductive layer 22 is within the above range, the performances of both conductivity and transparency can be well maintained. In addition, even when the thickness of the optical sheet 11 is thick, the transparent conductive layer 22 is formed by a sputtering method, and the thickness of the transparent conductive layer 22 is within the above range, the thickness of the transparent conductive laminate 21 can be promoted. .

Since the transparent electroconductive laminate 21 includes the optical sheet 11, the optical sheet 11 can be prevented from being curled, and the change in the phase difference of the retardation film 2 due to the occurrence of curl can be effectively prevented. Further, since the transparent conductive laminate 21 includes the optical sheet 11, the hardness of one surface side of the retardation film 2 can be effectively improved. Further, by making the refractive index of the high refractive index layer 12 close to the refractive index of the transparent conductive layer 22, the transparent conductive laminated body 21 is used for, for example, a touch panel. In this case, the visibility of the electrode pattern formed on the transparent conductive layer 22 can be lowered.

The difference between the refractive index of the high refractive index layer 12 and the refractive index of the transparent conductive layer 22 is not particularly limited, but is preferably 0.6 or less, more preferably 0.5 or less, and particularly preferably 0.3 or less. By making the difference between the refractive index of the high refractive index layer 12 and the refractive index of the transparent conductive layer 22 within the above range, the transparent conductive laminated body 21 can further reduce the visibility of the electrode pattern formed on the transparent conductive layer 22.

Fourth embodiment Touch panel 31

The touch panel 31 of FIG. 4 is a capacitive touch panel. The touch panel 31 is disposed on the surface side (the side on which the person is viewed) on the liquid crystal panel (not shown). The touch panel 31 includes a transparent conductive laminate 21, a glass substrate 32, and an adhesive layer 33. The transparent electroconductive laminate 21 of the present embodiment is the same as the transparent electroconductive laminate 21 of FIG. 3, and therefore the same reference numerals are given thereto, and the description thereof is omitted. Further, the liquid crystal panel includes a liquid crystal layer and a pair of polarizing plates which are disposed on the front side and the back side of the liquid crystal layer.

The transparent conductive laminate 21 is disposed such that the optical sheet 11 is located on the surface side of the touch panel 31, and the transparent conductive layer 22 is located on the liquid crystal panel side of the touch panel 31. The transparent conductive laminate 21 is disposed such that the fast axis direction of the retardation film 2 is at an angle of 45° with respect to the polarization axis of the polarizing plate disposed on the surface side of the liquid crystal layer. The transparent conductive laminate 21 is laminated on the glass substrate 32 via the adhesive layer 33. The adhesive layer 33 is not particularly limited, and an adhesive layer of a conventional adhesive resin such as an acrylic resin or a urethane resin may be used.

The image light transmission function of the touch panel 31 will be described. The polarized light emitted from the polarizing plate disposed on the surface side of the liquid crystal layer is converted into circularly polarized light after being transmitted through the retardation film 2 (in addition, in the case where the retardation film 2 is a 1/2 wavelength film, the polarized light is rotated 90°). Thus, looking at the LCD screen through sunglasses (polarized sunglasses) In this case, the crossed-Nicol state can be avoided, so that the image can be seen.

Since the touch panel 31 includes the optical sheet 11, the curling of the optical sheet 11 can be prevented, and the change in the phase difference of the retardation film 2 due to the occurrence of curl can be effectively prevented. Further, since the touch panel 31 includes the optical sheet 11, the hardness of one surface side of the retardation film 2 can be effectively improved. Further, by making the refractive index of the high refractive index layer 12 close to the refractive index of the transparent conductive layer 22, the touch panel 31 can reduce the visibility of the electrode pattern formed on the transparent conductive layer 22.

Fifth embodiment Touch panel 41

The touch panel 41 of FIG. 5 is a resistive film type touch panel. The touch panel 41 is disposed on the surface side of the liquid crystal panel (not shown). The touch panel 41 includes a transparent conductive laminate 21, a plurality of dot spacers 42, a columnar spacer 43, a transparent conductive film 44, a high refractive index layer 45, and a glass substrate 46. Since the transparent electroconductive laminate 21 of the present embodiment is the same as the transparent electroconductive laminate 21 of FIG. 3, the transparent electroconductive laminate 21 of the present embodiment is denoted by the same reference numeral, and the description thereof is omitted. Further, the liquid crystal panel includes a liquid crystal layer and a pair of polarizing plates which are disposed on the front side and the back side of the liquid crystal layer.

A plurality of dot spacers 42 are formed on the surface of the transparent conductive film 44. The material for forming the dot spacer 42 may, for example, be an insulating resin such as an epoxy resin or a bismuth resin. The column spacer 43 is disposed between the transparent conductive layer 22 and the transparent conductive film 44. The material for forming the columnar spacer 43 may, for example, be an insulating resin such as an epoxy resin, a polyester or an acrylic resin. The columnar spacer 43 is fixed to the edge portion on the back side of the transparent conductive layer 22, and is fixed to the edge portion on the surface side of the transparent conductive film 44. The column spacer 43 is configured to separate the transparent conductive layer 22 and the transparent conductive film 44. Transparent conductive film 44 is formed on the surface side of the high refractive index layer 45. The material for forming the transparent conductive film 44 is not particularly limited, and may be the same material as the material for forming the transparent conductive layer 22. The forming material can be applied to the surface of the high refractive index layer 45 by the same method as the transparent conductive layer 22, whereby the transparent conductive film 44 is formed. The high refractive index layer 45 is laminated on the surface of the glass substrate 46. The material for forming the high refractive index layer 45 is not particularly limited, and may be the same material as the material for forming the high refractive index layer 12. The lamination method of the high refractive index layer 45 is not particularly limited, and for example, it may be laminated on the surface of the glass substrate via an adhesive layer (not shown). The adhesive layer is not particularly limited, and may be the same adhesive layer as the above-described adhesive layer.

The image light transmission function of the touch panel 41 will be described. The polarized light emitted from the polarizing plate disposed on the surface side of the liquid crystal layer is converted into circularly polarized light after being transmitted through the retardation film 2. Thereby, in the case where the liquid crystal screen is viewed through the sunglasses (polarized sunglasses), the crossed nibs state can be avoided, and the image can be seen.

Since the touch panel 41 includes the optical sheet 11, it is possible to prevent the optical sheet 11 from being curled, and it is possible to effectively prevent a change in the phase difference of the retardation film 2 caused by the occurrence of curl. Further, since the touch panel 41 includes the optical sheet 11, the hardness of one surface side of the retardation film 2 can be effectively improved. Further, by bringing the refractive index of the high refractive index layer 12 close to the refractive index of the transparent conductive layer 22, the touch panel 41 can reduce the visibility of the electrode pattern formed on the transparent conductive layer 22.

Other embodiments

Further, the optical sheet of the present invention, the transparent electroconductive laminate including the optical sheet, and the touch panel including the transparent electroconductive laminate can be variously modified and improved in addition to the above-described modes. For example, the optical sheet may have an adhesive layer formed on the other surface side. As the adhesive layer, an acrylic tree can be exemplified. An adhesive layer of a conventional adhesive resin such as a fat or a urethane resin. The adhesive layer can be formed by applying a binder solution to the other side of the retardation film or the high refractive index layer, and then drying the binder solution. In addition, the adhesive solution may be pre-coated on one side of the release paper to dry the adhesive solution, and then the release paper with the adhesive is attached to the retardation film or the high refractive index layer to form a bond. Floor.

In addition, the optical sheet may be dispersed in the second hard coating layer containing _{ZnO, TiO 2, CeO 2,} SnO 2, ITO, Cs 0.33 WO 3, Al2O 3, La 2 O 3, ZrO 2, Y 2 O 3 , etc. Ultrafine particles, thereby increasing the refractive index. According to this configuration, the optical sheet can bring the refractive index of the second hard coat layer close to the refractive index of the transparent conductive layer. Therefore, by providing a transparent conductive layer on the second hard coat layer, the optical sheet can reduce the visibility of the electrode pattern formed on the transparent conductive layer.

The retardation film of the optical sheet need not necessarily be a 1/4 wavelength film, and may be a 1/2 wavelength film, a 3/4 wavelength film, or the like. The 1/4 wavelength film and the 3/4 wavelength film utilize circularly polarized light characteristics, and the 1/2 wavelength film utilizes a property of rotating polarized light by 90°. When the polarized sunglasses are worn to form a crossed nibble state, the polarized light is rotated by 90° with a 1/2 wavelength film to be in a parallel nicols state. The above optical sheet may also be laminated with other layers (for example, a UV absorbing layer, an antistatic layer, an antireflection layer, etc.) on the second hard coat layer. The foregoing optical sheet may also include an intermediate layer between the retardation film and the first hard coat layer, between the first hard coat layer and the second hard coat layer, and between the retardation film and the high refractive index layer. In the optical sheet described above, the first hard coat layer and the second hard coat layer may be sequentially formed on the other surface side of the retardation film. The optical sheet can be used for various touch panels such as a capacitive method, a resistive film method, and an electromagnetic induction method. The optical sheet can also be used for a stereoscopic image display device and other various liquid crystal display modules.

Industrial applicability

As described above, the optical sheet of the present invention, the transparent electroconductive laminate including the optical sheet, and the touch panel including the transparent electroconductive laminate can improve the light The hardness of the film is improved, and curling can be effectively prevented, so that the change in phase difference can be prevented, and it can be suitably used for a touch panel and various other liquid crystal display modules.

1‧‧‧ optical film

2‧‧‧ phase difference film

3‧‧‧hard coating

4‧‧‧First hard coating

5‧‧‧Second hard coating

Claims (12)

An optical sheet comprising: a retardation film containing a transparent polymer as a main component; a first hard coat layer formed on one side of the retardation film; and a second hard coat layer formed on the first hard coat layer One side of the layer; the pencil hardness of the second hard coat layer is 3H or more; the pencil hardness of the first hard coat layer is smaller than the pencil hardness of the second hard coat layer; and the thickness of the first hard coat layer is 20 μm or more 100 μm or less; the thickness of the second hard coat layer is 1 μm or more and 10 μm or less; the thickness of the first hard coat layer is 4 times or more and 20 times or less of the thickness of the second hard coat layer; one side of the first hard coat layer The arithmetic mean roughness (Ra) of the side is 0.5 μm or more and 8 μm or less; and the difference (Ha-Hw) between the haze (Ha) of the optical sheet in air and the haze (Hw) in water is 1.0% or less. The optical sheet according to claim 1, wherein the pencil hardness of the first hard coat layer is F or more and 2H or less. The optical sheet according to claim 1, wherein the transparent polymer is a polycarbonate resin, a cycloolefin resin or an acrylic resin. The optical sheet according to claim 1, wherein the main component of the first hard coat layer is an ultraviolet curable resin. The optical sheet according to claim 4, wherein the ultraviolet curable resin is a cationically polymerizable resin. The optical sheet of claim 4, wherein the first hard coat layer contains an ultraviolet ray-resistant agent. The optical sheet according to claim 1, wherein the retardation film is a 1/4 wavelength film or a 1/2 wavelength film. The optical sheet according to claim 1, wherein the optical sheet further includes a high refractive index layer formed on the other surface side of the retardation film. The optical sheet according to claim 8, wherein the high refractive index layer has a refractive index of 1.6 or more and 2.3 or less. A transparent conductive laminate comprising: the optical sheet according to claim 9; and a transparent conductive layer laminated on the other surface of the high refractive index layer of the optical sheet. The transparent electroconductive laminate according to claim 10, wherein a difference between a refractive index of the high refractive index layer and a refractive index of the transparent conductive layer is 0.6 or less. A touch panel comprising the transparent electroconductive laminate described in claim 10 or 11.