JP2013097041A - Image display unit and protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an image display unit that makes it possible to satisfactorily view an image even when the image is viewed through polarization sunglasses, that can be easily thinned even when a protective film is provided for preventing panel scatter and scratch, and that hinders occurrence of interference fringe.SOLUTION: The image display unit comprises: an image display module in which light emitted from an image display part is linear polarization; a transparent panel provided on the upper part of the image display module, and having a protective film stuck to at least one face thereof. In the image display unit, the protective film has a hard coat layer on at least one face of a 1/4λ phase difference film. On the surface of an image display screen, an angle θ1 between a polarization direction of the linear polarization emitted from the image display part and the direction of a delayed phase axis of the 1/4λ phase difference film, and an angle θ2 between the polarization direction of the linear polarization emitted from the image display part and the direction of the other axis of the 1/4λ phase difference film are both 15 to 75°.

Description

  The present invention includes an image display module in which light emitted from the image display unit is linearly polarized light, and a transparent panel provided on an upper portion of the image display module, and a protective film is attached to at least one surface of the transparent panel. The present invention relates to an image display device and a protective film used for the image display device.

  Image display devices such as a liquid crystal display (LCD) and an organic EL display are used in a wide range of fields including personal computers. In particular, portable electronic terminals such as electronic notebooks, mobile phones, smartphones, portable audio players, PDAs, and tablet terminals are becoming increasingly smaller and thinner in recent years, and there is also a demand for higher definition due to support for video playback functions and the like. It is high. As such an image display device, for example, an image display module such as an LCD module or an organic EL module is included in the configuration, and a transparent panel for protecting the image display module is provided above the image display module. An image display device is used.

  In an image display device such as an LCD, the emitted light is often linearly polarized for convenience of the module configuration. Therefore, when viewing an image using polarized sunglasses or the like, there is a problem that the emitted linearly polarized light is orthogonal to the polarized sunglasses and the image cannot be seen.

  As a means for solving this problem, there is a method of converting linearly polarized light into circularly polarized light by attaching a retardation film or a polarizing film in an image display device (see Patent Document 1). However, in an image display device having an image display module in which the light emitted from the image display unit is linearly polarized light, the image display module already has a polarizing plate and a polarizing film. In the case where a film or a polarizing film is provided, there are problems that the light transmittance is greatly lowered by the other number of retardation films, and that the material and the manufacturing cost are increased. Moreover, in the portable electronic terminal, when these retardation films and polarizing films are provided, it is difficult to meet the demand for thinning.

  In recent years, glass panels are often used as the transparent panel for the purpose of improving the design and texture of electronic devices, and the protective film for preventing damage to the glass and preventing the glass from scattering when broken is transparent. It is provided on the panel (see Patent Document 2). However, if the protective film is provided in the configuration having the retardation film or the polarizing film in the image display module as described above, it is difficult to meet the demand for thinning the image display device. Moreover, in the structure which provided the said protective film, an interference fringe produced and visibility might deteriorate.

JP 2004-268835 A JP 2010-275385 A

  The problem to be solved by the present invention is that images can be viewed well even when viewed through polarized sunglasses, and even when a protective film for preventing panel scattering and scratches is provided, it is easy to reduce the thickness, and interference fringes. An object of the present invention is to realize an image display device that is less likely to cause the problem.

  The present invention includes an image display module in which light emitted from the image display unit is linearly polarized light, and a transparent panel provided on an upper portion of the image display module, and a protective film is attached to at least one surface of the transparent panel. In the image display device, the protective film is a protective film having a hard coat layer on at least one surface of a ¼λ retardation film, and the linearly polarized light emitted from the image display unit on the surface of the image display surface. The angle θ1 formed by the polarization direction and the slow axis direction of the 1 / 4λ phase difference film, the polarization direction of the linearly polarized light emitted from the image display unit, and the other axis direction of the 1 / 4λ phase difference film The above-mentioned problem is solved by an image display device characterized in that the angle θ2 formed by each is 15 to 75 °.

  According to the image display device of the present invention, an image can be viewed well even when viewed through polarized sunglasses without providing a retardation film or a polarizing film in the image display module. Moreover, since it is not necessary to have many retardation films and polarizing films, and interference fringes that are likely to occur when a surface protective film is provided can be suppressed, good visibility can be realized. Furthermore, it is easy to reduce the thickness while having these excellent visibility and panel scattering and scratch resistance. For this reason, the image display device of the present invention is often used outdoors, and there is a high demand for thinning when carrying it. Also, there is a case where a scratch or panel crack may occur due to dropping or the like during operation. Very useful for applications.

It is the schematic which shows the example of a shape of the protective film used for this invention. It is the schematic which shows the polarization direction of the linearly polarized light in the image display apparatus of this invention. It is the schematic which shows the slow axis direction of the phase difference film used for the protective film in the image display apparatus of this invention. It is the schematic which shows angle (theta) 1 and (theta) 2 which the polarization direction of a linearly polarized light and the other axial direction of a phase difference film make in the image display apparatus of this invention. It is the schematic of evaluation of the image visibility in the Example of this invention. It is an evaluation result of image visibility in an image display device of Example 1 of the present invention. It is an evaluation result of image visibility in an image display device of Example 4 of the present invention. It is an evaluation result of image visibility in an image display device of comparative example 3 of the present invention. It is an evaluation result of image visibility in an image display device of comparative example 7 of the present invention.

  The present invention includes an image display module in which light emitted from the image display unit is linearly polarized light, and a transparent panel provided on an upper portion of the image display module, and a protective film is attached to at least one surface of the transparent panel. The protective film is a protective film based on a 1 / 4λ phase difference film, and on the surface of the image display surface, the polarization direction of linearly polarized light emitted from the image display unit, The angle θ1 formed by the slow axis direction of the ¼λ retardation film, and the angle θ2 formed by the polarization direction of the linearly polarized light emitted from the image display unit and the other axis direction of the ¼λ retardation film. And the protective film used in the image display device.

[Image display device]
In the image display device of the present invention, the polarization direction of linearly polarized light emitted from the image display unit of the image display module and the slow axis direction of the 1 / 4λ retardation film are formed on the surface of the image display surface of the image display device. The image is such that both the angle θ1 and the angle θ2 formed by the polarization direction of the linearly polarized light emitted from the image display unit and the other extension axis direction of the ¼λ retardation film are 15 to 75 °. It is an image display device in which a transparent panel having the protective film attached thereon is provided on the display module. Hereinafter, an example of the configuration will be described with reference to the drawings.

  In the present invention, the polarization direction of linearly polarized light refers to an image display device having a transparent panel 2 on an upper part of an image display module 1 that emits linearly polarized light 3, and the transparent panel 2 covers the image display surface 4 on the surface of the image display device. When configured, it refers to the polarization direction 5 (polarization axis) of the linearly polarized light 3 on the image display surface 4 (FIG. 2). The polarization direction may be any direction, but when the image display unit of the image display module has a substantially square shape, the angle ψ1 formed by the polarization direction and the side of the image display unit or the polarization direction It is preferable that the angle ψ2 formed by the base is 0 to 15 °. Since the polarization direction of the linearly polarized light can be easily recognized when the angle ψ1 is within this range, the angle θ1 formed by the polarization direction of the linearly polarized light and the slow axis direction of the 1 / 4λ retardation film, and the polarization of the linearly polarized light It becomes easy to adjust the angle θ2 formed by the direction and the other axial direction of the ¼λ retardation film.

  Further, the protective film is molded into a desired shape, preferably a square shape, by a punching process or the like according to the mode to be used. At this time, the slow axis direction in the 1 / 4λ retardation film of the protective film may be any direction. For example, in the case of a square-shaped protective film, each side of the protective film 6 and the axial direction, even if the protective film 6 is aligned with the sides 7 and 8 in the axial directions 7 and 8 (FIG. 3A). A protective film (FIG. 3B) in which 7 and 8 do not coincide may be used (the arrow in FIG. 3 is the axial direction of the 1 / 4λ retardation film).

  The image display device of the present invention has an angle θ1 formed by the polarization direction 5 of linearly polarized light emitted from the image display unit of the image display module and the slow axis extension direction of the ¼λ retardation film on the surface of the image display surface. And the angle θ2 formed by the polarization direction of the linearly polarized light emitted from the image display unit and the other axial direction of the ¼λ retardation film is 15 to 75 °, preferably 30 to 60 °. is there. Further, it is more preferably 40 to 50 °, and most preferably 43 to 47 °. In the present invention, by setting these θ1 and θ2 within the above ranges, visibility from all directions can be ensured easily and inexpensively even when polarized sunglasses are used.

  Θ1 and θ2 in the rectangular protective film are as shown in FIGS. 4A and 4B, and on the image display surface 4, the polarization direction 5 of linearly polarized light emitted from the image display unit of the image display module, and The angle formed by one slow axis direction 7 of the 1 / 4λ retardation film is θ1, the polarization direction 5 of the linearly polarized light emitted from the image display unit, and the other axial direction 8 of the 1 / 4λ retardation film Is the angle θ2. Note that θ1 and θ2 are angles on the narrow angle side among the angles formed by the polarization direction and the axial direction. Further, any axial direction may be used as a reference.

  When the axial direction of the 1 / 4λ retardation film is not orthogonal, the image display device may be configured such that each of θ1 and θ2 falls within the above range.

[Image display module]
The image display module in the present invention is not particularly limited as long as the emitted light from the image display unit is linearly polarized light, and examples thereof include an LCD module and an organic EL module. The module of the present invention also includes a module laminate in which a touch panel module or the like is provided on the upper part of these modules.

  The shape of the image display unit of the image display module is preferably a substantially square shape. The substantially square shape facilitates incorporation into various display devices, particularly small electronic terminals. In the present invention, the substantially square shape means a rectangular or square square shape (FIG. 1 (a)), as well as a shape in which arbitrary corners of the square shape, preferably four corners are chamfered (FIG. 1 (b)). , (C)) and the like approximate to a square shape.

  When the image display unit of the image display module has a substantially square shape, an angle ψ1 formed by the polarization direction of linearly polarized light emitted from the image display unit and the side of the image display unit is 0 to 5 °. It is preferable. As described above, since the angle ψ1 is within this range, the polarization direction of the linearly polarized light can be easily recognized, so that the angle θ1 formed by the polarization direction of the linearly polarized light and the slow axis direction of the 1 / 4λ retardation film, And it becomes easy to adjust the angle θ2 formed by the polarization direction of the linearly polarized light and the other axial direction of the ¼λ retardation film.

  Moreover, it is also preferable that the angle ψ2 formed by the polarization direction of the linearly polarized light emitted from the image display unit and the bottom side of the image display unit is 0 to 5 °. In this range as well, the polarization direction of linearly polarized light can be easily recognized, so that the angle θ1 and the angle θ2 can be easily adjusted.

[Transparent panel]
Although the transparent panel used for this invention is not specifically limited, As a panel generally used, there exist a glass plate, (meth) acrylic resin, polycarbonate resin, polyethylene terephthalate resin, etc. Particularly in recent years, it is preferable to use a glass panel for the purpose of improving the design and texture of an electronic device.

  The glass panel is preferably a tempered glass plate. Examples of the tempered glass include tempered glass manufactured by HOYA, Gorilla glass manufactured by Corning, and IG3 manufactured by Ishizuka Glass. Examples of a method for strengthening the glass plate include a physical strengthening method and a chemical strengthening method. In particular, chemical strengthening methods include an ion exchange method and an air cooling strengthening method. Examples of the material of the glass plate include float glass, alkali glass, and alkali-free glass.

  In addition, the transparent panel includes a case where an electrode layer or the like is patterned and has a function of a touch sensor or the like.

  A decorative part may be provided in a transparent panel. The decoration portion includes characters and figures that are visually recognized around the screen display portion of the mobile electronic terminal, or a black or white background provided on the back of these. These decorative portions are preferable because they can be easily provided by printing on a transparent panel. The printing method and printing ink are not particularly limited, and a commonly used printing method such as silk printing or pad printing or printing ink can be used.

  The thickness of the transparent panel is preferably 50 μm to 3 mm, preferably 75 μm to 2 mm, and more preferably 100 μm to 1 mm. When the thickness of the transparent panel is within the above range, the thickness can be reduced when applied to an electronic terminal.

[Protective film]
The protective film used in the present invention is a protective film having a 1 / 4λ retardation film as a base material and having a hard coat layer on at least one surface of the base material.

  The shape of the protective film used in the present invention may be any shape, but is preferably a substantially square shape because it can be easily incorporated into various display devices, particularly small electronic terminals.

  When the shape of the protective film used in the present invention is a substantially square shape, the angle α1 formed by the slow axis direction of the ¼λ retardation film substrate and one side of the substrate, and 1 / The angle α2 formed by the other axial direction of the 4λ retardation film substrate and the side orthogonal to one side of the substrate is preferably 15 to 70 °, and more preferably 30 to 65 °. Specifically, for example, the angle α1 formed between the side of the substantially rectangular protective film and the slow axis direction of the ¼λ retardation film substrate is 15 to 70 °, and the base (or the top) An angle α2 formed by the other axial direction of the ¼λ retardation film substrate is set to 15 to 70 °. Α1 and α2 are angles on the narrow angle side among the angles formed by the sides of the protective film and the axial direction, and the axial direction may be based on either.

  The total thickness of the protective film used in the present invention is 300 μm or less, preferably 50 to 300 μm, and more preferably 100 to 250 μm. By making the thickness within this range, it becomes easy to achieve both prevention of damage to the panel and durability against impacts and reduction in thickness of the image display device.

  The protective film of the present invention preferably has high transparency from the viewpoint of use in an image display device.

  The total light transmittance in the visible light wavelength region of the protective film of the present invention is preferably 85% or more, more preferably 90% or more, haze of 1.0 or less, particularly preferably 0.5 or less. When the total light transmittance and the haze are within the above ranges, the protective film has high transparency, and the display screen is easily refined.

[1 / 4λ retardation film]
The quarter-wave retardation film serving as the base material of the protective film preferably has an in-plane retardation [Re] value in the range of 120 to 170 nm obtained by spectral transmittance measurement with 550 nm measurement light. Further, the numerical value of the in-plane retardation is more preferably in the range of 130 to 160 nm, and most preferably 135 to 150 nm.

  Examples of the 1 / 4λ retardation film include a liquid crystal polymer film, a polycarbonate film, a cycloolefin resin film, an acrylic resin film, and the like.

  The 1 / 4λ phase difference film is preferably a polycarbonate type 1 / 4λ phase difference film, a non-bornene type 1 / 4λ phase difference film, a 1 / 4λ phase difference ZEONOR film, or the like, and more preferably a polycarbonate type 1 / 4λ phase difference film. Most preferably, a phase difference film is used. By using a polycarbonate-based film composed mainly of polycarbonate, particularly a 1 / 4λ retardation film made of polycarbonate, interference fringes when bonded to a transparent panel can be suppressed. In addition, in a high temperature environment, the amount of gas generated from the inside of the film can be easily reduced, and deterioration of visibility due to foaming can be easily suppressed.

  The thickness of the ¼λ retardation film is preferably 25 to 200 μm, more preferably 50 to 150 μm, and most preferably 75 to 125 μm. By making the thickness within this range, it becomes easy to achieve both prevention of damage to the panel and durability against impacts and reduction in thickness of the image display device.

[Hard coat layer]
As the hard coat layer used in the present invention, a hard coat layer usually used as a protective film for an image display device or the like can be used, and any hard coat layer can be used without particular limitation as long as it can prevent scratches. As the hard coat layer, when the hard coat film is formed by laminating with the retardation film, the hard coat layer preferably has a pencil hardness of F or more, and preferably H or more. . By setting the hardness to F or higher, the ability to prevent scratches on the transparent panel can be improved.

  In addition, it is preferable that the hard coat layer has high transparency or does not contain a polarizing substance because it becomes easy to obtain suitable visibility. As the transparency of the hard coat layer, the total light transmittance of the hard coat layer is 85%, preferably 90% or more. The haze value is preferably 1.0 or less, and particularly preferably 0.5 or less.

  The hard coat agent used in the hard coat layer is not particularly limited as long as it has the above-mentioned characteristics. However, since the hard coat layer can be easily formed, a hard coat comprising an active energy ray-curable resin composition is used. An agent can be preferably used. As such an active energy ray-curable resin composition, a polyfunctional acrylate resin composition is preferable, and a urethane acrylate hard coat agent is particularly preferable.

  Among these, urethane acrylate-based hard coat agents include urethane, which is an addition reaction product of polyisocyanate (a1) and acrylate (a2) having one hydroxyl group and two or more (meth) acryloyl groups in one molecule. A hard coat agent containing an acrylate (A) can be preferably used. The urethane acrylate (A) has an α, β-unsaturation having a functional group capable of reacting with the reactive functional group in the (meth) acrylate polymer (b1) having a reactive functional group in the side chain. It is also preferred to use a polymer (B) having a (meth) acryloyl group obtained by reacting the compound (b2).

  Examples of the polyisocyanate (a1) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4 Aromatic isocyanate compounds such as 4,4'-diphenylmethane diisocyanate; alicyclic hydrocarbons such as dicyclohexylmethane diisocyanate, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated methylenebisphenylene diisocyanate, 1,4-cyclohexane diisocyanate Compound having two bonded isocyanate groups (hereinafter abbreviated as alicyclic diisocyanate); trimethylene diisocyanate, hexamethylene diisocyanate Compounds having two isocyanate groups attached to aliphatic hydrocarbons over preparative like (hereinafter, referred to as aliphatic diisocyanates.) And the like. These polyisocyanates can be used alone or in combination of two or more.

  Of these polyisocyanates (a1), aliphatic diisocyanates or alicyclic diisocyanates are preferable, and among them, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated methylene bisphenylene diisocyanate, and hexamethylene diisocyanate are preferable. In particular, norbornane diisocyanate is most preferable.

  Examples of the acrylate (a2) having one hydroxyl group and two or more (meth) acryloyl groups in one molecule include trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta ( Examples include polyacrylates of polyhydric hydroxyl group-containing compounds such as (meth) acrylate, adducts of these polyacrylates with ε-caprolactone, adducts of these polyacrylates with alkylene oxide, epoxy acrylates, etc. Can be mentioned. These acrylates (a2) can be used alone or in combination of two or more.

  Of these acrylates (a2), an acrylate having one hydroxyl group and 3 to 5 (meth) acryloyl groups in one molecule is preferable. Examples of such acrylates include pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and the like, and these are particularly preferable because a cured film having high hardness can be obtained.

  The urethane acrylate (A) used in the present invention is obtained by subjecting two components of the polyisocyanate (a1) and the acrylate (a2) to an addition reaction. The ratio of the acrylate (a2) to 1 equivalent of the isocyanate in the polyisocyanate (a1) is usually preferably 0.1 to 50, more preferably 0.1 to 10, and preferably 0.9 to 1.2 as the hydroxyl equivalent. Is more preferable. Moreover, 30-150 degreeC is preferable and, as for the reaction temperature of the said polyisocyanate (a1) and the said acrylate (a2), 50-100 degreeC is more preferable.

  The blending amount of the urethane acrylate (A) in 100 parts by weight of the resin component in the resin composition is preferably 5 to 90 parts by weight, more preferably 10 to 70 parts by weight, and even more preferably 10 to 60 parts by weight. . If the blending amount of the urethane acrylate (A) is within this range, a cured film having a sufficiently high hardness can be obtained, and there is no coating film defect, excellent surface antifouling properties, and curing shrinkage is reduced. Curling of a film having a cured coating can also be reduced.

  The molecular weight of the urethane acrylate (A) is preferably in the range of 500 to 1,500. When the molecular weight is within this range, a cured film having a sufficiently high hardness can be obtained and the curing shrinkage can be reduced, so that the curl of the film having the cured film can also be reduced.

  The blending amount of the urethane acrylate (A) in 100 parts by weight of the resin component in the resin composition is preferably 5 to 90 parts by weight, more preferably 10 to 70 parts by weight, and even more preferably 10 to 60 parts by weight. . If the blending amount of the urethane acrylate (A) is within this range, a cured film having a sufficiently high hardness can be obtained, and there is no coating film defect, excellent surface antifouling properties, and curing shrinkage is reduced. Curling of a film having a cured coating can also be reduced.

  As the reactive functional group of the (meth) acrylate polymer (b1) having a reactive functional group in the side chain used in the present invention, a hydroxyl group, a carboxyl group, an epoxy group or the like is preferable. Moreover, as a functional group which the (alpha), (beta)-unsaturated compound (b2) which can react with these reactive functional groups has, an isocyanate group, a carboxyl group, an acid halide group, a hydroxyl group, an epoxy group etc. are preferable. The (meth) acrylate polymer (b1) having a reactive functional group in the side chain was reacted with an α, β-unsaturated compound (b2) having a functional group capable of reacting with the reactive functional group. The method for producing the polymer (B) having a (meth) acryloyl group is not particularly limited and can be produced by various methods.

  The hard coat film used in the present invention can be produced by applying a hard coat agent on a film substrate and curing it.

  Examples of methods for applying a hard coating agent to a film substrate include gravure coating, roll coating, comma coating, air knife coating, kiss coating, spray coating, transfer coating, dip coating, spinner coating, wheeler coating, brush coating, and silk. Examples thereof include a solid coat using a screen, a wire bar coat, and a flow coat. Also, printing methods such as offset printing and letterpress printing may be used. Among these, gravure coating, roll coating, comma coating, air knife coating, kiss coating, wire bar coating, and flow coating are preferable because a coating film having a more constant thickness can be obtained.

  Curing of the hard coating agent may be appropriately performed according to the hard coating agent to be used, but when the active energy ray-curable resin composition is used as the hard coating agent, the activity of light, electron beam, radiation, etc. What is necessary is just to harden with an energy ray. Specific energy sources or curing devices include, for example, germicidal lamps, ultraviolet fluorescent lamps, carbon arc, xenon lamps, high pressure mercury lamps for copying, medium or high pressure mercury lamps, ultrahigh pressure mercury lamps, electrodeless lamps, metal halide lamps, natural light, etc. Or an electron beam using a scanning type or curtain type electron beam accelerator.

  Among these, ultraviolet rays are particularly preferable, and irradiation in an inert gas atmosphere such as nitrogen gas is preferable in terms of increasing the polymerization efficiency. Further, if necessary, heat may be used as an energy source and heat treatment may be performed after curing with active energy rays.

  When ultraviolet rays are used as a device for irradiating active energy rays, the light source is a low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, electrodeless lamp (fusion lamp), chemical lamp, black light. Lamps, mercury-xenon lamps, short arc lamps, helium / cadmium lasers, argon lasers, sunlight, LEDs and the like can be mentioned. In addition, when the active energy ray-curable resin composition used in the present invention is applied to a film substrate to form a cured film, a flashing xenon-flash lamp is used. This is preferable because the influence of heat can be reduced.

[Adhesive layer]
Moreover, in the protective film used for this invention, it is also preferable to provide an adhesive layer in one surface of the base material which consists of said 1 / 4lambda phase difference film. The protective film having the structure is preferable because it can be easily attached to the transparent panel.

  As the pressure-sensitive adhesive layer, it is preferable to use a pressure-sensitive adhesive layer having a thickness of 5 to 50 μm. In the present invention, by setting the thickness of the pressure-sensitive adhesive layer to the thickness, sufficient adhesive strength with the object to be adhered can be expressed, and even when stress concentration occurs on the surface of the protective adhesive film, the protective adhesive Since the elastic modulus of the entire film can be kept high, it is easy to prevent damage to the panel.

  For the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer, known acrylic, rubber-based, and silicone-based pressure-sensitive resins can be used. Among them, an acrylic copolymer containing a (meth) acrylic acid ester monomer having an alkyl group having 2 to 14 carbon atoms as a main monomer component is from the viewpoint of transparency, light resistance and heat resistance. preferable.

  Specific examples of the (meth) acrylic acid ester monomer having 2 to 14 carbon atoms include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n -Hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate , Sec-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, - octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate and the like.

  Among them, a methacrylic acid alkyl ester monomer having an alkyl side chain having 4 to 9 carbon atoms or an acrylic acid alkyl ester monomer having an alkyl side chain having 4 to 9 carbon atoms is preferable, and the carbon number is More preferred are alkyl acrylate monomers having 4 to 9 alkyl side chains. Of these, n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, and ethyl acrylate are particularly preferable. By using a (meth) acrylic acid alkyl ester having an alkyl side chain with a carbon number within the range, it is easy to ensure a suitable adhesive force.

  The content of the (meth) acrylic acid ester monomer having 2 to 14 carbon atoms in the monomer constituting the acrylic copolymer used for the pressure-sensitive adhesive layer is preferably 60% by mass or more, and 80 More preferably, it is at least mass%. It becomes easy to ensure suitable adhesive force by setting it as content of the said C2-C14 (meth) acrylic acid ester monomer in a (meth) acrylic acid ester copolymer.

  Acrylic copolymers further contain (meth) acrylic acid ester monomers and other vinyl monomers having polar groups such as hydroxyl, carboxyl and amino groups in the side chain as monomer components. It is preferable to do.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, hydroxypropyl (meth) acrylate, and caprolactone-modified (meth) acrylate. Hydroxyl group-containing (meth) acrylates such as polyethylene glycol mono (meth) acrylate and polypropylene glycol (meth) acrylate can be used, among which 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxy It is preferred to use hexyl (meth) acrylate as a copolymerization component.

  As the monomer having a carboxyl group, acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, (meth) acrylic acid dimer, ethylene oxide-modified succinic acid acrylate, etc. can be used. It is preferable to use it as a copolymerization component.

  Examples of the monomer having a nitrogen atom include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, acryloylmorpholine, acrylamide, N, N-dimethylacrylamide, and 2- (perhydrophthalimido-N-yl) ethyl acrylate. An amide group-containing vinyl monomer can be used, and among these, N-vinyl-2-pyrrolidone, N-vinylcaprolactam, and acryloylmorpholine are preferably used as the copolymerization component.

  Examples of vinyl monomers having other polar groups include vinyl acetate, acrylonitrile, maleic anhydride, itaconic anhydride and the like.

  The content of the monomer having a polar group is preferably 0.1 to 20% by weight of the monomer component constituting the acrylic copolymer, more preferably 1 to 13% by weight, More preferably, it is 1.5 to 8% by weight. By containing in the said range, it is easy to adjust the cohesive force, holding force, and adhesiveness of an adhesive to a suitable range.

  The weight average molecular weight Mw of the acrylic copolymer can be measured by gel permeation chromatograph (GPC).

  Further, in order to increase the cohesive strength of the pressure-sensitive adhesive layer, it is preferable to add a crosslinking agent in the pressure-sensitive adhesive. As a crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, a chelate type crosslinking agent etc. are mentioned, for example. The addition amount of the crosslinking agent is preferably adjusted so that the gel fraction of the pressure-sensitive adhesive layer is 30 to 90%. A more preferable gel fraction is 50 to 85%. Among these, 60 to 80% is most preferable. It becomes easy to suppress the fall of the surface pencil hardness when a protective adhesive film is affixed on a panel as a gel fraction is 30% or more. Moreover, it becomes easy to suppress the outgas generated from the 1 / 4λ retardation film in a high temperature environment, and the generation of bubbles at the interface between the pressure-sensitive adhesive layer and the film can be suppressed. On the other hand, when the gel fraction is 90% or less, suitable adhesiveness can be easily obtained. The gel fraction is expressed as a percentage of the original weight by measuring the weight after drying the insoluble content remaining after 24 hours of immersion in the adhesive layer after curing.

  Furthermore, in order to improve the adhesive strength of the pressure-sensitive adhesive layer, a tackifier resin may be added. The tackifying resin to be added to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is an acrylic copolymer, a rosin resin such as rosin or an esterified rosin; a terpene such as a diterpene polymer or an α-pinene-phenol copolymer. Examples of such resins include: petroleum resins such as aliphatic (C5) and aromatic (C9); styrene resins, phenolic resins, xylene resins, and the like. In order to reduce the b * value of the pressure-sensitive adhesive layer after standing at 100 ° C. for 14 days to 6 or less, there are few unsaturated double bonds, esterified products of hydrogenated rosin and disproportionated rosin, aliphatic and aromatic series It is preferable to add petroleum tree etc. to the adhesive layer

  As the addition amount of the tackifier resin, when the pressure-sensitive adhesive resin is an acrylic copolymer, it is preferable to add 10 to 60 parts by weight with respect to 100 parts by weight of the acrylic copolymer. When importance is attached to adhesiveness, it is most preferable to add 20 to 50 parts by weight. Further, when the pressure-sensitive adhesive resin is a rubber-based resin, it is preferable to add 80 to 150 parts by weight of the tackifier resin with respect to 100 parts by weight of the rubber-based resin. In general, when the adhesive resin is a silicone resin, no tackifying resin is added.

  In addition to the above, known and commonly used additives can be added to the adhesive. For example, in order to improve the adhesion to glass, a silane coupling agent can be added in the range of 0.001 to 0.005. In addition, plasticizers, softeners, fillers, pigments, flame retardants, and the like can be added.

  The weight average molecular weight Mw of the acrylic copolymer used for the pressure-sensitive adhesive layer is preferably 400,000 to 1,400,000, and more preferably 600,000 to 1,200,000. When the weight average molecular weight Mw of the acrylic copolymer is within the above range, it is easy to secure a suitable adhesive force, and when a protective adhesive film is obtained, the load on the film surface can be relaxed suitably.

Moreover, the range storage modulus (G ') of 3.0 × ¹⁰ 4 ~2.0 × ^{10 5} at 85 ° C. of the dynamic viscoelasticity spectrum measured at a frequency 1Hz of the adhesive is preferable, 5. The range of 0 × 10 ^{4 to} 1.5 × 10 ⁵ is more preferable, and the range of 7.0 × 10 ^{4 to} 1.2 × 10 ⁵ is most preferable. By setting the storage elastic modulus at 85 ° C. within the above range, it is possible to achieve both the adhesion to the ¼λ retardation film in a high temperature environment (85 °) and the cohesive force inside the pressure-sensitive adhesive. Outgas generated from the 4λ retardation film is easily suppressed.

  The dynamic viscoelasticity of the pressure-sensitive adhesive layer in the present invention is obtained by sandwiching a test piece between parallel disks, which are measuring parts of the tester, using a viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD). , Obtained by measuring the storage elastic modulus (G ′) and loss elastic modulus (G ″) at a frequency of 1 Hz. However, in the latter case, the thickness of the pressure-sensitive adhesive is adjusted to be in the above-mentioned range. .

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

[Preparation of hard coating agent]
<Synthesis of urethane acrylate (UA1)>
In a flask equipped with a stirrer, a gas introduction tube, a cooling tube, and a thermometer, 254 parts by weight of butyl acetate, 222 parts by weight of isophorone diisocyanate (hereinafter referred to as “IPDI”), 0.5 part by weight of p-methoxyphenol, dibutyl After charging 0.5 parts by weight of tin diacetate and raising the temperature to 70 ° C., a mixture of pentaerythritol triacrylate (hereinafter referred to as “PE3A”) / pentaerythritol tetraacrylate (hereinafter referred to as “PE4A”) (weight ratio). 75/25 mixture) 795 parts by weight were added dropwise over 1 hour. After completion of the dropwise addition, the mixture is reacted at 70 ° C. for 3 hours, and further reacted until the infrared absorption spectrum of 2250 cm −1 indicating an isocyanate group disappears, and a urethane acrylate (UA1) / PE4A mixture (a mixture of 80/20 by weight, non-volatile) 80% by weight butyl acetate solution). The molecular weight of urethane acrylate (UA1) was 818.

<Synthesis of polymer>
In a flask equipped with a stirrer, a gas introduction pipe, a cooling pipe, and a thermometer, 250 parts by weight of glycidyl methacrylate (hereinafter referred to as “GMA”), 1.3 parts by weight of lauryl mercaptan, and methyl isobutyl ketone (hereinafter referred to as “MIBK”). 1000 parts by weight and 7.5 parts by weight of 2,2′-azobisisobutyronitrile (hereinafter referred to as “AIBN”) were charged and the mixture was stirred at 90 ° C. over 1 hour while stirring under a nitrogen stream. The temperature was raised and reacted at 90 ° C. for 1 hour. Next, a mixture of 750 parts by weight of GMA, 3.7 parts by weight of lauryl mercaptan, and 22.5 parts by weight of AIBN was added dropwise over 2 hours while stirring at 90 ° C., followed by reaction at 100 ° C. for 3 hours. Thereafter, 10 parts by weight of AIBN was charged and further reacted at 100 ° C. for 1 hour, and then heated to around 120 ° C. and reacted for 2 hours. Cool to 60 ° C., replace the nitrogen inlet tube with an air inlet tube, add 507 parts by weight of acrylic acid (hereinafter referred to as “AA”), 2 parts by weight of p-methoxyphenol, and 5.4 parts by weight of triphenylphosphine. After mixing, the reaction solution was bubbled with air, heated to 110 ° C., and reacted for 8 hours. Thereafter, 1.4 parts by weight of p-methoxyphenol was added, and after cooling to room temperature, MIBK was added so that the nonvolatile content was 50% by weight, and the above polymer (MIBK solution having a nonvolatile content of 50% by weight) was obtained. . In addition, the weight average molecular weight of the obtained polymer was 31,000 (in terms of polystyrene by GPC), and the (meth) acryloyl group equivalent was 300 g / eq.

  3.1 parts by weight of ethyl acetate, 40.0 parts by weight of a butyl acetate solution (non-volatile content 80%) of a urethane acrylate (UA1) / PE4A mixture (a mixture of 80/20 by weight), a MIBK solution (non-volatile content) of the above polymer 50%) 64.0 parts by weight, dipentaerythritol hexaacrylate (hereinafter referred to as “DPHA”) 16.0 parts by weight, photoinitiator 1-hydroxycyclohexyl phenyl ketone (hereinafter referred to as “HCPK”) 1.63 1 part by weight, 1.16 parts by weight of photoinitiator diphenyl-2,4,6-trimethylbenzoylphosphine oxide (hereinafter referred to as “TPO”) are uniformly mixed to prepare a resin composition (non-volatile content: 65%). did.

<Adjustment of hard coating agent>
100 parts by weight of a MIBK solution (non-volatile content: 50% by weight) of the resin composition prepared by the above method and 2 parts by weight of a reactive fluorine antifouling agent (OPTOOL DAC; manufactured by Daikin Industries, Ltd., non-volatile content: 20% by weight) After mixing, the hard coating agent (A) was obtained by diluting with ethyl acetate such that the nonvolatile content was 40% by weight.

[Preparation of pressure-sensitive adhesive composition]
<Preparation of acrylic copolymer, etc.>
An acrylic copolymer and an acrylic mixture were prepared as shown below with the composition shown in Table 1 (the amount in the table is part by mass).

<Acrylic copolymer (1)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 85 parts by weight of butyl acrylate, 15 parts by weight of methyl methacrylate, 4 parts by weight of acrylic acid, dimethylaminoethyl 1 part by mass of acrylate was dissolved in ethyl acetate and polymerized to obtain an acrylic copolymer (1) having a mass average molecular weight (Mw) of 700,000 (solid content 25%).

<Acrylic copolymer (2)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 65 parts by mass of butyl acrylate, 30 parts by mass of methyl acrylate, 5 parts by mass of 2-hydroxyethyl acrylate It melt | dissolved in ethyl acetate and superposed | polymerized and obtained the acrylic copolymer (2) of mass mean molecular weight (Mw) 400,000 (solid content 48%).

[Preparation of pressure-sensitive adhesive composition]
Using the above acrylic copolymer, a pressure-sensitive adhesive composition was prepared as follows with the formulation shown in Table 2 (the blending amount in the table is parts by mass).

<Adhesive composition (a)>
To 100 parts by mass of the acrylic copolymer (1), 0.60 part by mass of an epoxy-based crosslinking agent (E-2XM solid content 2%, manufactured by Soken Chemical Co., Ltd.) is added, and the mixture is stirred with a stirrer for 20 minutes. (A) was obtained.

<Adhesive composition (b)>
To 100 parts by mass of the acrylic copolymer (1), 1.20 parts by mass of an epoxy-based crosslinking agent (E-2XM solid content 2%, manufactured by Soken Chemical Co., Ltd.) is added, and stirred with a stirrer for 20 minutes to obtain an adhesive composition. (B) was obtained.

<Adhesive composition (c)>
To 100 parts by mass of the acrylic copolymer (2), 0.05 part by mass of an isocyanate-based crosslinking agent (Coronate HL solid content: 75% by Nippon Polyurethane Co., Ltd.) was added and stirred with a stirrer for 20 minutes. c) was obtained.

<Adhesive composition (d)>
To 100 parts by mass of the acrylic copolymer (2), 0.25 parts by mass of an isocyanate-based crosslinking agent (Coronate HL solid content 75% manufactured by Nippon Polyurethane Co., Ltd.) was added and stirred with a stirrer for 20 minutes. d) was obtained.

[Preparation of protective film]
Using the hard coat agent and the pressure-sensitive adhesive composition, a protective film was produced as follows.

<Preparation of protective film A>
The hard coat agent (A) prepared above was applied to one side of a PC 1 / 4λ retardation film (Pure Ace manufactured by Teijin Kasei Co., Ltd.) having a thickness of 70 μm, dried at 60 ° C. for 90 seconds, and then in an air atmosphere. Using a UV irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb), UV light is irradiated with an irradiation light amount of 0.5 J / cm ² , and the thickness is 10 μm. A layer was formed. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (a) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A 38 μm-thick polyester film (hereinafter referred to as # 38 release film), one side of which was peeled off with a silicone compound, was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film A having a total thickness of 128 μm It was.

<Preparation of protective film B>
The hard coat agent (A) prepared above was applied to one side of a PC 1 / 4λ retardation film (Pure Ace manufactured by Teijin Kasei Co., Ltd.) having a thickness of 70 μm, dried at 60 ° C. for 90 seconds, and then in an air atmosphere. Using a UV irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb), UV light is irradiated with an irradiation light amount of 0.5 J / cm ² , and the thickness is 10 μm. A layer was formed. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (b) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film B having a total thickness of 128 μm.

<Preparation of protective film C>
The hard coat agent (A) prepared above was applied to one side of a PC 1 / 4λ retardation film (Pure Ace manufactured by Teijin Kasei Co., Ltd.) having a thickness of 70 μm, dried at 60 ° C. for 90 seconds, and then in an air atmosphere. Using a UV irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb), UV light is irradiated with an irradiation light amount of 0.5 J / cm ² , and the thickness is 10 μm. A layer was formed. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (c) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the surface of the obtained pressure-sensitive adhesive layer and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film C having a total thickness of 128 μm.

<Preparation of protective film D>
The hard coat agent (A) prepared above was applied to one side of a PC 1 / 4λ retardation film (Pure Ace manufactured by Teijin Kasei Co., Ltd.) having a thickness of 70 μm, dried at 60 ° C. for 90 seconds, and then in an air atmosphere. Using a UV irradiation device (“F450” manufactured by Fusion UV Systems Japan Co., Ltd., lamp: 120 W / cm, H bulb), UV light is irradiated with an irradiation light amount of 0.5 J / cm ² , and the thickness is 10 μm. A layer was formed. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (d) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film D having a total thickness of 128 μm.

<Preparation of protective film E>
The hard coat agent (A) prepared above was applied to one side of a 87λ-thick 1 / 4λ phase difference ZEONOR film (manufactured by Nippon Zeon Co., Ltd.), dried at 60 ° C for 90 seconds, and then irradiated with ultraviolet rays in an air atmosphere. (Fusion UV Systems Japan Co., Ltd. “F450”, lamp: 120 W / cm, H bulb) is used to irradiate ultraviolet rays with an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. did. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (a) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the surface of the obtained pressure-sensitive adhesive layer and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film E having a total thickness of 145 μm.

<Preparation of protective film F>
The hard coating agent (A) prepared above was applied to one side of a 75 μm thick PET film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.), dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet irradiation device (fusion UV) in an air atmosphere. Using a “F450” manufactured by Systems Japan Co., Ltd., a lamp: 120 W / cm, an H bulb, an ultraviolet ray was irradiated at an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (a) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the surface of the obtained pressure-sensitive adhesive layer and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film F having a total thickness of 133 μm.

<Preparation of protective film G>
The hard coating agent (A) prepared above was applied to one side of a 75 μm thick PET film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.), dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet irradiation device (fusion UV) in an air atmosphere. Using a “F450” manufactured by Systems Japan Co., Ltd., a lamp: 120 W / cm, an H bulb, an ultraviolet ray was irradiated at an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (b) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the surface of the obtained pressure-sensitive adhesive layer and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film G having a total thickness of 133 μm.

<Preparation of protective film H>
The hard coating agent (A) prepared above was applied to one side of a 75 μm thick PET film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.), dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet irradiation device (fusion UV) in an air atmosphere. Using a “F450” manufactured by Systems Japan Co., Ltd., a lamp: 120 W / cm, an H bulb, an ultraviolet ray was irradiated at an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (c) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film H having a total thickness of 133 μm.

<Preparation of protective film I>
The hard coating agent (A) prepared above was applied to one side of a 75 μm thick PET film (Cosmo Shine A4100 manufactured by Toyobo Co., Ltd.), dried at 60 ° C. for 90 seconds, and then irradiated with an ultraviolet irradiation device (fusion UV) in an air atmosphere. Using a “F450” manufactured by Systems Japan Co., Ltd., a lamp: 120 W / cm, an H bulb, an ultraviolet ray was irradiated at an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (d) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film I having a total thickness of 133 μm.

<Preparation of protective film J>
The hard coating agent (A) prepared above is applied to one side of an isotropic PC film (Mitsubishi Gas Chemical Co., Ltd. Iupilon) having a thickness of 80 μm, dried at 60 ° C. for 90 seconds, and then irradiated with ultraviolet rays in an air atmosphere. (Fusion UV Systems Japan Co., Ltd. “F450”, lamp: 120 W / cm, H bulb) is used to irradiate ultraviolet rays with an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. did. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (a) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film J having a total thickness of 138 μm.

<Preparation of protective film K>
The hard coating agent (A) prepared above is applied to one side of an isotropic PC film (Mitsubishi Gas Chemical Co., Ltd. Iupilon) having a thickness of 80 μm, dried at 60 ° C. for 90 seconds, and then irradiated with ultraviolet rays in an air atmosphere. (Fusion UV Systems Japan Co., Ltd. “F450”, lamp: 120 W / cm, H bulb) is used to irradiate ultraviolet rays with an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 7 μm. did. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (b) was applied onto the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film K having a total thickness of 138 μm.

<Preparation of protective film L>
The hard coating agent (A) prepared above is applied to one side of an isotropic PC film (Mitsubishi Gas Chemical Co., Ltd. Iupilon) having a thickness of 80 μm, dried at 60 ° C. for 90 seconds, and then irradiated with ultraviolet rays in an air atmosphere. (Fusion UV Systems Japan Co., Ltd. “F450”, lamp: 120 W / cm, H bulb) is used to irradiate ultraviolet rays with an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 7 μm. did. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (c) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the surface of the obtained pressure-sensitive adhesive layer and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film L having a total thickness of 138 μm.

<Preparation of protective film M>
The hard coating agent (A) prepared above is applied to one side of an isotropic PC film (Mitsubishi Gas Chemical Co., Ltd. Iupilon) having a thickness of 80 μm, dried at 60 ° C. for 90 seconds, and then irradiated with ultraviolet rays in an air atmosphere. (Fusion UV Systems Japan Co., Ltd. “F450”, lamp: 120 W / cm, H bulb) is used to irradiate ultraviolet rays with an irradiation light amount of 0.5 J / cm ² to form a hard coat layer having a thickness of 10 μm. did. Next, the non-hard-coated surface was surface-treated with a corona treatment device so that the surface tension was 55 dynes / cm to obtain a hard-coated film. The pressure-sensitive adhesive (d) was applied on the corona-treated surface of the hard coat film so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm, and dried at 85 ° C. for 2 minutes. A # 38 release film was bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film M having a total thickness of 138 μm.

<Preparation of protective film N>
The pressure-sensitive adhesive (a) was applied to one side of a 70 μm-thick PC 1 / 4λ retardation film (Pure Ace manufactured by Teijin Chemicals Ltd.) so that the thickness of the pressure-sensitive adhesive layer after drying was 10 μm. Dried for 2 minutes. A # 38 release film was then bonded to the obtained pressure-sensitive adhesive layer surface and aged at 40 ° C. for 2 days to obtain a protective pressure-sensitive adhesive film N having a total thickness of 118 μm.

  The gel fraction and storage elastic modulus of the pressure-sensitive adhesive layer of the protective film obtained above were measured as follows. The obtained result is shown to Tables 1-2.

[Gel fraction of adhesive layer]
According to the manufacturing conditions of the said protective adhesive film, the adhesive layer was provided on the polyester film (what was peel-processed) so that the thickness after drying might be 10 micrometers, and the test piece was prepared. The test piece was cut into a size of 20 mm × 100 mm, the polyester film was peeled off, and the weight a before toluene extraction was measured. Next, after the same test piece was immersed in toluene for 24 hours, the gel was taken out and dried at 100 ° C. for 2 hours, and the weight b after toluene extraction was measured. The gel fraction was calculated from the following formula.
Gel fraction (%) = (b / a) × 100

[Storage modulus of adhesive layer]
According to the manufacturing conditions of the said protective adhesive film, the adhesive layer was provided on the polyester film (what peeled) so that the thickness after drying might be set to 50 micrometers, and the test piece was prepared. A sheet composed of an adhesive layer was prepared, and a test piece was prepared by superimposing up to 1 mm thickness. Using a viscoelasticity tester (trade name: Ares 2KFRTN1 manufactured by Rheometrix Co., Ltd.), a test piece was sandwiched between parallel disks as measurement parts of the tester, and the frequency was 1 Hz and the heating rate was 2 ° C./min. The storage elastic modulus (G ′) from 50 ° C. to 150 ° C. was measured to obtain a storage elastic modulus of 85 ° C.

[Production of image display device]
Using the protective film, an image display device was produced as follows.

<Example 1>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

<Example 2>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 50 °. The image display apparatus was manufactured by fixing at an angle.

<Example 3>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 40 °. The image display apparatus was manufactured by fixing at an angle.

<Example 4>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 30 °. The image display apparatus was manufactured by fixing at an angle.

<Example 5>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 60 °. The image display apparatus was manufactured by fixing at an angle.

<Example 6>
A protective film B cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film B is bonded, and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

<Example 7>
A protective film C cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film C is bonded and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

<Example 8>
A protective film D cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film D is bonded and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

<Example 9>
A protective film E cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel is composed of a glass panel in which the protective film E is bonded and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

<Comparative Example 1>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 90 °. The image display apparatus was manufactured by fixing at an angle.

<Comparative example 2>
A protective film A cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film A is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 0 °. The image display apparatus was manufactured by fixing at an angle.

<Comparative Example 3>
A protective film F cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel is the first to be bonded to the glass panel in which the protective film F is bonded to the liquid crystal module in which the light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by one stretched axis direction of the biaxially stretched PET film of the protective film and the linearly polarized light emitted from the image display portion of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle. Note that 45 ° was the angle at which the luminance was most improved.

<Comparative example 4>
A protective film G cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film G is bonded, and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by one stretching axis direction of the PET film as the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display device was manufactured by fixing.

<Comparative Example 5>
A protective film H cut out in a rectangular shape is pasted on one surface of a transparent glass panel, and the glass panel is the top of the glass panel on which the protective film H is pasted together and the liquid crystal module in which the light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by one stretching axis direction of the PET film as the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display device was manufactured by fixing.

<Comparative Example 6>
A protective glass I cut into a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel is a glass panel having the protective film I bonded thereto and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by one stretching axis direction of the PET film as the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display device was manufactured by fixing.

<Comparative Example 7>
A protective film J cut out in a rectangular shape is bonded to one side of a transparent glass panel, and the glass panel is composed of a glass panel in which the protective film J is bonded and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. The image display device was manufactured by fixing the angle γ between the side of the protective film at this time and the linearly polarized light emitted from the image display unit of the liquid crystal module to be 0 °, 30 °, 60 °, and 90 °. .

<Comparative Example 8>
A protective film K cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel is a glass panel in which the protective film K is bonded together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. The image display device was manufactured by fixing the angle γ between the side of the protective film at this time and the linearly polarized light emitted from the image display unit of the liquid crystal module to be 0 °, 30 °, 60 °, and 90 °. .

<Comparative Example 9>
A protective film L cut out in a rectangular shape is pasted on one surface of a transparent glass panel, and the glass panel is composed of a glass panel in which the protective film L is pasted and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. The image display device was manufactured by fixing the angle γ between the side of the protective film at this time and the linearly polarized light emitted from the image display unit of the liquid crystal module to be 0 °, 30 °, 60 °, and 90 °. .

<Comparative Example 10>
A protective film M cut out in a rectangular shape is bonded to one surface of a transparent glass panel, and the glass panel includes a glass panel in which the protective film M is bonded and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. The image display device was manufactured by fixing the angle γ between the side of the protective film at this time and the linearly polarized light emitted from the image display unit of the liquid crystal module to be 0 °, 30 °, 60 °, and 90 °. .

<Comparative Example 11>
A protective film N cut out in a rectangular shape is pasted on one surface of a transparent glass panel, and the glass panel is composed of a glass panel in which the protective film N is pasted together and a liquid crystal module in which light emitted from the image display unit is linearly polarized light. It fixed so that it might be located in the upper part. At this time, on the glass panel surface (image display surface surface), the angle formed by the slow axis direction of the 1 / 4λ retardation film of the protective film and the linearly polarized light emitted from the image display unit of the liquid crystal module is 45 °. The image display apparatus was manufactured by fixing at an angle.

  The image display devices obtained in the above examples and comparative examples were evaluated as follows. The obtained results are shown in Tables 3-4.

[Verification of image visibility]
A polarizing plate that transmits only linearly polarized light orthogonal to the linearly polarized light emitted from the liquid crystal module was installed on the upper part of the image display devices manufactured in the above-described examples and comparative examples. The polarizing plate was rotated 360 °, and the visibility of the image emitted from the image display device was confirmed (FIG. 5). The evaluation criteria were as follows. The evaluation results are shown in Tables 4-6. Further, FIG. 6 shows the result of confirming the visibility of the image display device of Example 1, FIG. 7 shows the result of confirming the visibility in the region where the luminance is lowered in the image display device of Example 3, and Comparative Example 1 FIG. 8 shows the result of confirming the visibility in the area where the image becomes dark in the image display apparatus of FIG. The cursors in FIGS. 6 to 8 are images on the image display unit.
A: The luminance does not change over the entire rotation region, has very good luminance, and the image visibility is very good over the entire rotation region.
A: The luminance hardly changes in the entire rotation range, has a good luminance, and the image visibility in the entire rotation range is good.
(Triangle | delta): There exists an area | region where a brightness | luminance falls in a part of rotation area, and although it feels a little dark in the said area | region, it has image visibility which can be used in the whole rotation area.
X: The image becomes dark in a part of the rotation region, and the image is hardly visible in the region.

[Interference fringes]
In the image display devices manufactured in the above examples and comparative examples, the images emitted from the image display devices were confirmed, and it was confirmed whether interference fringes were generated.
The evaluation criteria were as follows.
○: No interference fringes ×: Interference fringes

[Glass panel scattering prevention]
Evaluation of the intensity | strength of glass and anti-scattering property was performed based on the 3 point | piece bending test method of JISR1601 specification. The surface on the protective film side of the glass panel (Comparative Example 16 is a glass panel without a protective film) on which the protective film of the image display device produced in the above Examples and Comparative Examples was bonded was fixed at two points. Next, stress was applied to the center of the glass panel side, and the stress when the glass was broken and the degree of scattering of the glass were confirmed. The evaluation criteria for glass scattering were as follows.
○: No glass fragments scattered ×: Glass fragments scattered

[Measurement of surface pencil hardness]
The release film of the protective film obtained in the above Examples and Comparative Examples was peeled off and attached to a glass plate. The pencil hardness of the hard coat layer surface was measured using a pencil scratch tester (manual type) for coating film manufactured by Imoto Seisakusho Co., Ltd. based on the provisions of JIS K 5600-5-4 (1999 edition). The evaluation criteria were as follows.
○: Not scratched with a pencil of hardness H Δ: Not scratched with a pencil of hardness F ×: Scratched with a pencil of hardness F

[Heat resistance test]
The protective film produced by the above method is bonded to a glass plate having a thickness of 5 mm, a length of 50 mm, and a width of 40 mm (an alternative to an image display device), and subjected to heat and pressure treatment at 5 atm, 50 ° C. for 20 minutes. It was. Thereafter, the bonded sample was put into an 85 ° C. heater, and when the entire panel was observed with a microscope (300 times magnification) after 24 hours, it was confirmed whether bubbles were mixed in or peeled off. The evaluation criteria were as follows.
◎: No bubbles of 5 μm or more ○: No bubbles of 30 μm or more Δ: Within 20 bubbles of 30 μm or more ×: 20 or more bubbles of 30 μm or more or peeling

[Measurement of total light transmittance and haze]
The protective film was affixed to a glass plate having a thickness of 0.5 mm, a length of 50 mm, and a width of 40 mm, and then fixed by performing heat and pressure treatment at 5 atm, 50 ° C. for 20 minutes. The total light transmittance and haze were measured based on JIS K7105 and JIS K7136 of the sample using “HR-100 type” manufactured by Murakami Color Research Laboratory.

DESCRIPTION OF SYMBOLS 1 Image display module 2 Transparent panel 3 Linearly polarized light radiate | emitted from an image display module 4 Image display surface surface 5 Polarization direction of linearly polarized light 6 Protective film 7 The slow axis direction of a film base material 8 The other axial direction of a film base material 11 Liquid crystal module that emits linearly polarized light 12 Protective film 13 Transparent glass panel 14 Polarizing plate

Claims (12)

  An image display device comprising: an image display module in which light emitted from the image display unit is linearly polarized light; and a transparent panel provided on an upper portion of the image display module, and a protective film attached to at least one surface of the transparent panel The protective film is a protective film having a hard coat layer on at least one surface of a ¼λ retardation film, the polarization direction of linearly polarized light emitted from the image display unit, and the retardation of the retardation film. The angle θ1 formed by the phase axis direction and the angle θ2 formed by the polarization direction of the linearly polarized light emitted from the image display unit and the other axial direction of the ¼λ retardation film are both 15 to 75 °. An image display device characterized by that.   The image display device according to claim 1, wherein the ¼λ retardation film is a polycarbonate film.   The image display device according to claim 1, wherein the protective film is a protective film having an adhesive layer on a surface side to be attached to a transparent panel of a ¼λ retardation film. 4. The image display according to claim 3, wherein the storage elastic modulus at 85 ° C. of the dynamic viscoelastic spectrum measured at a frequency of 1 Hz of the pressure-sensitive adhesive layer is in the range of 3.0 × 10 ^{4 to} 2.0 × 10 ^5. apparatus.   The image display device according to claim 3 or 4, wherein a gel fraction of the pressure-sensitive adhesive layer is in a range of 30 to 90%.   The image display unit of the image display module has a substantially square shape, and an angle ψ1 formed by a polarization direction of linearly polarized light emitted from the image display unit and a side of the image display unit is 0 to 15 °. The image display apparatus in any one of 1-5.   2. The image display unit of the image display module has a substantially square shape, and an angle ψ2 formed by a polarization direction of linearly polarized light emitted from the image display unit and a bottom side of the image display unit is 0 to 15 °. The image display apparatus in any one of -6.   A protective film attached to at least one surface of the transparent panel of an image display device, comprising: an image display module in which light emitted from the image display unit is linearly polarized light; and a transparent panel provided on the image display module. A protective film comprising a hard coat layer on at least one surface of a 1 / 4λ retardation film.   The protective film according to claim 8, wherein the ¼λ retardation film is a polycarbonate film.   The protective film of Claim 8 or 9 which has an adhesive layer in the surface side stuck on the transparent panel of the said 1/4 (lambda) phase difference film. 11. The protective film according to claim 10, wherein a storage elastic modulus at 85 ° C. of a dynamic viscoelastic spectrum measured at a frequency of 1 Hz of the pressure-sensitive adhesive layer is in a range of 3.0 × 10 ^{4 to} 2.0 × 10 ^5.   The protective film according to claim 10 or 11, wherein the pressure-sensitive adhesive layer has a gel fraction of 30 to 90%.