KR102294328B1 - Optical film and polarizing plate - Google Patents

Abstract

An object of the present invention is to provide an optical film capable of suppressing the problem that the luminance improving film delaminates during peeling of the surface protection film.
As the optical film 20 provided with the surface protection film 22 and the brightness improving film 21, after irradiating the active energy ray whose accumulated light amount is 8000 mJ/cm<2>, when peeling the surface protection film from the brightness improving film The required pulling force is 10.0 N/25 mm or less, and the increase rate of the pulling force is less than 700%.

Description

Optical film and polarizer {OPTICAL FILM AND POLARIZING PLATE}

The present invention relates to an optical film and a polarizing plate.

A polarizing plate is an optical element having a function of absorbing linearly polarized light having an oscillation plane parallel to the absorption axis direction and transmitting linearly polarized light having an oscillation plane perpendicular to the absorption axis, and is used, for example, in a liquid crystal display device.

In the liquid crystal display device, two polarizing plates are used, and one each is arranged on the back side and the front side of the liquid crystal cell. By laminating a brightness enhancing film on a polarizing plate disposed on the back side, brightness can be improved and the contrast of a liquid crystal display device can be improved. In portable devices, such as a small smart phone and a tablet terminal, since the load capacity of a battery is limited, the demand of the polarizing plate which has a brightness improvement film from which the power saving effect is acquired is increasing.

The luminance enhancing film is an optical element having a function of transmitting polarized light perpendicular to the direction of the reflection axis and reflecting parallel polarized light, for example, it is known that a plurality of polymer thin films having different refractive indices are alternately laminated have.

As for the polarizing plate which has a brightness improvement film, in order to protect the surface until it is bonded to a liquid crystal cell, a surface protection film is temporarily adhered to the surface of a brightness improvement film in many cases. After bonding a polarizing plate to a liquid crystal cell, this surface protection film is peeled and removed from a polarizing plate (for example, refer patent document 1).

In recent years, in the manufacturing process of bonding a polarizing plate and a touchscreen, for adhesive improvement between films, or hardening of a liquid glue, processing, such as heating, UV irradiation, and force application, is performed in many cases (for example, refer patent document 2) ). Although Patent Document 2 describes a surface protection film with a small peeling force, when the adherend member of the surface protection film is the above-described brightness enhancing film, the surface protection film described in Patent Document 2 cannot solve the problem of delamination. there was no

Patent Document 1: Japanese Patent Laid-Open No. 2004-258393 Patent Document 2: Japanese Patent Laid-Open No. Hei 8-60111

As mentioned above, a brightness improving film is a laminated body of 2 types or more layers, and the adhesiveness of adjacent layers is not very high.

Therefore, in a line for cutting a polarizing plate having a surface protection film or a brightness enhancing film into a predetermined shape, potential cracks are likely to occur on the end surface of the brightness enhancing film, and a polarizing plate for use as a product is bonded to a liquid crystal cell. When a surface protection film was peeled later, peeling arose between the layers of each film in a brightness improvement film, and there existed a problem that a part of brightness improvement film would peel off with a surface protection film. This phenomenon is called delamination. In particular, the peeling force with respect to the to-be-adhered body of a surface protection film exists in the tendency which rises when an adhesive layer changes in quality by the said process, as described in patent document 2. In particular, when the active energy ray of the ultraviolet region is irradiated, the peeling force increases remarkably.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide an optical film and a polarizing plate capable of suppressing the problem that the luminance improving film delaminates during peeling of the surface protection film.

One aspect of the present invention is an optical film having a surface protection film and a brightness enhancing film, wherein the pulling force required when peeling the surface protection film from the brightness enhancing film after irradiation with active energy rays is 10.0 N/ There is provided an optical film that is 25 mm or less, and the rate of increase of the pulling force is less than 700%.

In one aspect of the present invention, the surface protection film is laminated on the brightness enhancing film through an adhesive layer, and the adhesive layer is an optical film having a transmittance of 5% or less with respect to the active energy ray having a wavelength of 190 nm. may do

One aspect of the present invention provides a polarizing plate having the optical film of the above aspect and a polarizing film.

In this specification, the laminated body which has a brightness improvement film and a surface protection film may be simply called an optical film.

In the present invention, it is possible to provide an optical film and a polarizing plate capable of suppressing the problem that the luminance improving film delaminates between layers during peeling of the surface protection film.

1 is a diagram showing an embodiment of the present invention, and is a schematic cross-sectional view of a polarizing plate 50 .
FIG. 2 : is a figure which shows the relationship between the distance and force at the time of pulling the surface protection film 22 from the brightness improvement film 21. As shown in FIG.
3 : is a top view at the time of measuring the pulling force at the time of peeling the surface protection film 22 in the polarizing plate 50 from a brightness improvement film.
4 : is sectional drawing at the time of measuring the pulling force at the time of peeling the surface protection film 22 from a brightness enhancement film.
It is a figure which shows the specification and evaluation of an Example, a comparative example, and a reference example.
It is a schematic sectional drawing of the surface protection film in an Example, a comparative example, and a reference example.
7 : is a figure which shows the relationship between pulling force and the delamination generation rate in the brightness improving film 21. As shown in FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the optical film and polarizing plate of this invention is described with reference to FIGS. 1-7.

<Polarizer>

1 is a schematic cross-sectional view of a polarizing plate 50 . The polarizing plate 50 has the structure in which the polarizing film 10 and the optical film 20 were laminated|stacked. In addition, in the following description, as shown in FIG. 1, in the polarizing plate 50, the side in which the optical film 20 is provided is called an upper side, and the side in which the polarizing film 10 is provided is called the lower side, and it demonstrates. However, this is merely defining the vertical direction for convenience of description, and does not limit the direction of use of the optical film 20 and the polarizing plate 50 according to the present invention.

<Polarizing film>

The polarizing film 10 is an absorption-type polarizing film (hereinafter, an absorption-type polarizing film 10), and has a protective film 11 on the lower side. As the absorptive polarizing film 10, a polyvinyl alcohol-based resin film in which a dichroic dye is adsorbed and oriented is usually used. The polyvinyl alcohol-based resin constituting the absorption-type polarizing film 10 is obtained by saponifying polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerized with vinyl acetate include unsaturated carboxylic acid, olefin, vinyl ether, unsaturated sulfonic acid, and acrylamide having an ammonium group. The saponification degree of polyvinyl alcohol-type resin is about 85 mol% - about 100 mol% normally, Preferably it is 98 mol% or more. This polyvinyl alcohol-type resin may be further modified|denatured, for example, polyvinyl formal, polyvinyl acetal, etc. which were modified|denatured with aldehyde can also be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, Preferably it is about 1,500-5,000. As specific polyvinyl alcohol-type resin and a dichroic dye, polyvinyl alcohol-type resin and a dichroic dye which are illustrated by Unexamined-Japanese-Patent No. 2012-159778 [patent document 3] are mentioned, for example.

What produced a film of polyvinyl alcohol-type resin is used as a raw film of the absorption type polarizing film 10. As shown in FIG. The method for producing a film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be produced by a known method. Although the thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is 150 micrometers or less. When the ease of extending|stretching etc. are also considered, the film thickness becomes like this. Preferably it is 3 micrometers or more, and it is preferable that it is 75 micrometers or less.

The absorption-type polarizing film 10 is, for example, a step of stretching a polyvinyl alcohol-based resin film by uniaxial stretching, dyeing the polyvinyl alcohol-based resin film with a dichroic dye, and adsorbing the dichroic dye, 2 The polyvinyl alcohol-based resin film to which the color dye has been adsorbed is subjected to a step of treating the film with an aqueous boric acid solution and a step of washing with water after treatment with the aqueous boric acid solution, and finally drying the film. In addition, the absorption type polarizing film 10 may be manufactured according to the method described in Unexamined-Japanese-Patent No. 2012-159778, for example. In this method, the polyvinyl alcohol-type resin layer used as the absorption type polarizing film 10 can be formed by coating a polyvinyl alcohol-type resin on a base film. The thickness of the absorption type polarizing film 10 is usually 1 µm to 40 µm, and preferably about 2 µm to 30 µm.

<Protection film>

As the protective film 11, a thermoplastic film formed of, for example, a thermoplastic resin is used. The thickness of the thermoplastic resin film is usually 3 µm to 100 µm, and preferably 5 µm to 50 µm. The thermoplastic resin film is preferably made of a resin excellent in transparency, uniform optical properties, mechanical strength, thermal stability, and the like. Specific examples of the thermoplastic resin include cellulose-based resins such as triacetyl cellulose and diacetyl cellulose, polyester-based resins such as polyethylene terephthalate, polyethylene isophthalate and polybutylene terephthalate, polymethyl (meth)acrylate, and polyethyl (meth)acrylic resins such as (meth)acrylate, polycarbonate-based resins, polyethersulfone-based resins, polysulfone-based resins, polyimide-based resins, polyolefin-based resins such as polyethylene and polypropylene, and polynorbornene-based resins can be heard Among them, a resin film formed of a cellulose-based resin, a polyester-based resin, a (meth)acrylic resin, a polycarbonate-based resin, and a polyolefin-based resin is preferable. Here, (meth)acrylate points out what may be either methacrylate or an acrylate, and "(meth)" at the time of saying other than (meth)acrylic acid etc. is the same.

An appropriate commercial item can be used for these thermoplastic resin films. Examples of commercially available cellulosic resin films are "Fujitak (registered trademark) TD80", "Fujitak (registered trademark) TD80UF" and "Fujitak (registered trademark) TD80UZ" manufactured by FUJIFILM Corporation under their brand names, respectively. ", "KC2UAW", "KC8UX2M" and "KC8UY&quot; manufactured by Konica Minolta Corporation.

An appropriate commercial item can be used for a polyester-type resin film. Examples of commercially available polyester resin films are "Diafoil (registered trademark)" manufactured by Mitsubishi Jushi Co., Ltd., "Lumiror (registered trademark)" manufactured by Toray Industries, Ltd., and Toyobo Co., Ltd. "Cosmoshine (registered trademark)" by Shiki Corporation, etc. are mentioned.

An appropriate commercial item can be used for the (meth)acrylic-type resin film. Examples of commercially available (meth)acrylic resin films are "Technoloy (registered trademark)" manufactured by Sumitomo Chemical Co., Ltd., and "Acriplene (registered trademark)" manufactured by Mitsubishi Rayon Co., Ltd. under the trade names, respectively. and the like.

An appropriate commercial item can be used for a polycarbonate-type resin film. When the example of the commercial item of a polycarbonate-type resin film is given, "Panlite (trademark)" etc. by the Teijin Kasei Co., Ltd. product are mentioned by a brand name, respectively.

As an example of a commercial item of a polyolefin resin, "Topas" manufactured by Topas Advanced Polymers GmbH and sold by Polyplastics Co., Ltd., "ARTON" (registered trademark) sold by JSR Corporation, Nippon "ZEONOR (registered trademark)" and "ZEONEX (registered trademark)" sold by Zeon Corporation, "Apel" (registered trademark) sold by Mitsui Chemicals Co., Ltd. ( As mentioned above, all are brand names) etc., and a film can be produced from these. In addition, a polyolefin resin film may be used, for example, "Aton Film" sold by JSR Co., Ltd. ("Aton" is a registered trademark of the company), "S" sold by Sekisui Chemical Co., Ltd. Sina" (registered trademark) and "Zeonoa Film" sold by Nippon Zeon Corporation (registered trademark), etc. are mentioned.

In addition, as the absorption type polarizing film 10, it is also possible to provide a protective film in the upper side other than the structure which has the protective film 11 in the lower side. Examples of the upper protective film include a luminance enhancing film, a laminate of a luminance enhancing film and a thermoplastic film, and the like.

<Brightness improvement film>

As the luminance enhancing film 21, for example, like a multilayer film of a dielectric or a multilayer laminate of layers having different refractive index anisotropy, it transmits linearly polarized light of a predetermined polarization axis and reflects other light. An oriented film or an oriented liquid crystal layer thereof is supported on a film substrate, and an appropriate one may be used, such as one that reflects the circularly polarized light of either left rotation or right rotation and transmits the other light. The kind of the layer which comprises the said multilayer laminated body can be made into 2 types or more. As the brightness improving film, for example, a material that generates a phase difference by stretching, typified by polyethylene naphthalate, polyethylene terephthalate, and polycarbonate, an acrylic resin typified by polymethyl methacrylate, "Aton" manufactured by JSR Corporation (registered trademark), a resin obtained by uniaxially stretching a resin having a small amount of retardation expression such as norbornene-based resin represented by (registered trademark) alternately as a multilayer laminate can be used. Specific examples of the brightness enhancing film include "DBEF" (registered trademark), "APF-V4" (product name), "APF-V3" (product name) and "APF-V2" (product name) manufactured by 3M Corporation. . The thickness of the brightness enhancing film is usually 5 µm to 100 µm, preferably 10 µm to 50 µm.

<Laminated body of brightness improvement film/thermoplastic resin film>

The laminate of the brightness enhancing film and the thermoplastic resin film may be one in which these films are laminated through, for example, an adhesive or an adhesive. What is necessary is just to select an appropriate well-known thing as an adhesive or an adhesive agent. It is preferable to use an adhesive from a viewpoint of the convenience of an adhesion|attachment operation, generation|occurrence|production prevention of optical distortion, etc. As the pressure-sensitive adhesive, for example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyether or the like as the base polymer can be employed. Among them, like the acrylic pressure-sensitive adhesive, it has excellent optical transparency, maintains appropriate wettability and cohesive force, has excellent adhesion to a luminance improving film and a thermoplastic resin film, and has good heat resistance, lifting and peeling under a high-temperature environment, etc. It is preferable to select and use one that does not cause a peeling problem.

The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive may contain fine particles for exhibiting light scattering properties as necessary, and fillers such as glass fibers, glass beads, resin beads, metal powder and other inorganic powders, pigments, colorants, antioxidants, You may contain a ultraviolet absorber etc. Examples of the ultraviolet absorber include a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

What provided the hard-cord layer in the surface on the opposite side to the bonding surface with a polarizing film may be sufficient as the protective film 11 and an upper protective film. Thereby, the scratch etc. which arise when processing a polarizing plate can be prevented. When providing a hard-coat layer, it is preferable that they are 1 micrometer - 8 micrometers, and, as for the thickness of a hard-coat layer, it is more preferable that they are 1 micrometer - 6 micrometers from a viewpoint of making protective property and a flexibility compatible. When the thickness of a hard-coat layer exceeds 8 micrometers, there exists a tendency for a flexibility to become low and to become easy to enter a crack at the time of bending|flexion. On the other hand, when the thickness of a hard-coat layer is less than 1 micrometer, although a flexibility is favorable, it exists in the tendency for sufficient characteristic from a viewpoint of in-plane uniformity not to be acquired in many cases.

The hard coat layer can be formed of a resin film layer. The resin material for forming the resin film layer has sufficient strength as a film after formation of the resin film layer and has transparency, and can be used without particular limitation. Examples of the resin include active energy ray curable resins such as thermosetting resins, thermoplastic resins, ultraviolet curable resins and electron beam curable resins, and two-component mixed resins.

Among them, ultraviolet curable resins can be cured by irradiation with ultraviolet rays, so that a resin film layer can be efficiently formed with a simple processing operation, and a light diffusion layer such as an anti-glare treatment layer can also be formed. Suitable. Examples of the UV-curable resin include various types of resin such as polyester, acrylic, urethane, amide, silicone, and epoxy, and include UV-curable monomers, oligomers, and polymers. The ultraviolet curable resin preferably used includes, for example, those having an ultraviolet polymerizable functional group, and among them, those containing an acrylic monomer or oligomer component having two or more, particularly three to six functional groups. Moreover, the ultraviolet-ray polymerization initiator is mix|blended with the ultraviolet curable resin.

As the method for forming the resin film layer, an appropriate known method can be adopted, for example, there is a method of coating the resin (coating solution) on the protective film 5 and drying it. When curable resin is used, a hardening process is performed after that. As the coating method of the coating solution, a method such as fountain, die coater, casting, spin coating, fountain metalling, gravure, or the like may be employed.

In addition, in coating, the coating solution may be diluted with a general solvent such as toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, ethyl alcohol, etc. may be

As a method of laminating|stacking the absorption type polarizing film 10 and a protective film, the method of adhering these films with an adhesive agent is normally employ|adopted. When the protective film is laminated on both surfaces of the absorbent polarizing film 10, an adhesive of the same type may be used, or an adhesive of a different type may be used.

As an adhesive agent, a water-based adhesive agent, a photocurable adhesive agent, etc. are mentioned. A water-based adhesive is what melt|dissolved the adhesive agent component in water, or what disperse|distributed the adhesive agent component in water, and can make an adhesive bond layer thin. Preferred examples of the water-based adhesive include those in which the main component of the adhesive (composition) is a polyvinyl alcohol-based resin or a urethane resin.

Polyvinyl alcohol-based resins, in addition to partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, amino group-modified polyvinyl alcohol, etc. polyvinyl alcohol-based resin may be used. When polyvinyl alcohol-type resin is used as an adhesive agent component, the adhesive agent is prepared as aqueous solution of polyvinyl alcohol-type resin in many cases. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of water.

It is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to an adhesive containing a polyvinyl alcohol-based resin as a main component in order to improve adhesiveness. As the water-soluble epoxy resin, for example, a polyamide obtained by reacting epichlorohydrin with a polyamide polyamine obtained by reaction of a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid. and polyamine epoxy resins. Commercially available products of such polyamide polyamine epoxy resins include "Sumirezin (registered trademark) 650(30)" and "Sumirezin (registered trademark) 675" sold by Taoka Chemical Co., Ltd. under their trade names, respectively; "WS-525" sold by Seiko PMC Co., Ltd., etc. exist, and these can be used suitably. The addition amount of these curable components or crosslinking agents is 1 weight part - 100 weight part normally with respect to 100 weight part of polyvinyl alcohol-type resin, Preferably they are 1 weight part - 50 weight part. When the amount added is small, the effect of improving the adhesiveness becomes small. On the other hand, when the amount added is large, the adhesive layer tends to become brittle.

The laminate (absorptive polarizing film 10 and protective film) bonded via a water-based adhesive is usually subjected to a drying treatment, and the adhesive layer is dried and cured. The drying treatment can be performed, for example, by spraying hot air. Drying temperature is about 40 degreeC - about 100 degreeC, Preferably it is selected suitably in the range of 60-100 degreeC. The drying time is, for example, about 20 seconds to 1,200 seconds. The thickness of the adhesive layer after drying is usually about 0.001 µm to 5 µm, preferably 0.01 µm or more, more preferably 2 µm or less, and still more preferably 1 µm or less.

When the thickness of an adhesive bond layer becomes large too much, it will become easy to become defective in the external appearance of a polarizing plate.

After the drying treatment, curing may be performed at a temperature of room temperature or higher for at least one day, usually for one day or longer, to obtain sufficient adhesive strength. Such curing is typically performed in a state wound up in a roll shape. A preferable curing temperature is in the range of 30°C to 50°C, and more preferably 35°C or higher and 45°C or lower. When the curing temperature exceeds 50°C, so-called “winding tightening” is likely to occur in a roll wound state. In addition, it is preferable that the humidity at the time of curing is suitably selected so that a relative humidity may become the range of 70% or less, for example. Curing time is about 1 to 10 days normally, Preferably it is about 2 to 7 days.

As a photocurable adhesive agent, the mixture etc. of a photocurable epoxy resin and a photocationic polymerization initiator are mentioned, for example. Examples of the photocurable epoxy resin include an alicyclic epoxy resin, an epoxy resin having no alicyclic structure, and a mixture thereof.

Moreover, as a photocurable adhesive agent, what added the radical polymerization type initiator and/or cationic polymerization type initiator to an epoxy resin, an acrylic resin, an octacene resin, a urethane resin, a polyvinyl alcohol resin, etc. can be used.

The laminate bonded through the photocurable adhesive cures the photocurable adhesive by irradiating an active energy ray after lamination. The light source of the active energy ray is, for example, preferably an active energy ray having a light emission distribution at a wavelength of 400 nm or less, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a chemical lamp, a black light lamp, microwave excitation A mercury lamp, a metal halide lamp, etc. are used preferably. The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive, and is not particularly limited, but the irradiation intensity in the wavelength region effective for activation of the polymerization initiator is 0.1 mW/cm 2 to 2500 mW/cm 2 it is preferable When the irradiation intensity is 0.1 mW/cm2 or more, the reaction time does not become too long, and when it is 2500 mW/cm2 or less, yellowing of the epoxy resin or deterioration of the polarizing plate due to heat radiated from the light source and heat generated during curing of the photocurable adhesive less likely to cause

Although the light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive to be cured, it is preferable that the amount of accumulated light expressed as the product of the irradiation intensity and the irradiation time is 10 mJ/cm 2 to 10,000 mJ/cm 2 . When the amount of accumulated light to the photocurable adhesive is 10 mJ/cm 2 or more, a sufficient amount of active species derived from the polymerization initiator can be generated and the curing reaction can proceed more reliably, and when it is 10,000 mJ/cm 2 or less, the irradiation time is not too long , good productivity can be maintained. In addition, the thickness of the adhesive bond layer after active energy ray irradiation is about 0.001 micrometer - about 5 micrometers normally, Preferably it is 0.01 micrometer or more, More preferably, it is 2 micrometers or less, More preferably, it is 1 micrometer or less.

When the photocurable adhesive is cured by irradiation with active energy rays, various functions of the polarizing plate such as the degree of polarization, transmittance and color of the polarizing film, and the transparency of transparent films such as acrylic resin films, optical compensation films, and protective films are reduced. It is preferable to perform hardening under the conditions which do not do it.

In addition, according to the irradiation conditions of the said active energy ray, it is limited when an appropriate surface protection film is selected so that it may correspond to Examples 1-3 below that it is possible to manufacture a product with good yield.

<Optical Film>

The optical film 20 is comprised by the brightness improving film 21 and the surface protection film 22 being laminated|stacked.

<Surface protection film>

6 is a schematic cross-sectional view of the surface protection film 22 . The surface protection film 22 adheres so that peeling is possible to the surface of the member to be protected (brightness improvement film 21), and aims at protecting this surface, The base material 1 and the brightness improving film ( 21) The adhesive layer 2 provided on the lower surface side, and the polymer layer 3 provided on the upper surface of a base material are provided.

As the base material 1, a synthetic resin made from polyethylene, polypropylene, polyester, polyimide, polycarbonate, etc. as a raw material and a laminate thereof can be used. Among them, in consideration of transparency and heat resistance at the time of use, 2 The axially stretched polyethylene terephthalate film is preferable. Any of unstretched, uniaxially stretched, and biaxially stretched may be sufficient as a resin film.

Moreover, you may control the draw ratio of a resin film and the orientation angle of an axial direction to a specific value. In addition to the above resin films, films made of other resins can be used as long as they have the required strength and optical aptitude. In addition, the surface of these base materials can also be subjected to an easily adhesive treatment such as a corona treatment.

The film thickness of this base material 1 is about 12 micrometers - 100 micrometers, Preferably, 20 micrometers - 80 micrometers are suitable. If the film thickness of the base material 1 is less than 12 µm, it is too thin, and it is difficult to protect the protective member due to dents caused by collisions of foreign objects. Since there is no such thing, the peeling operation|work of the surface protection film 22 also becomes difficult. Moreover, when the film thickness exceeds 80 micrometers, the rigidity of a base material is too large, and it is difficult to adhere uniformly with respect to a protective member without floating, and curl becomes large, and difficulty arises in bonding to a touch panel. Moreover, on the cost structure of the surface protection film 22, since the base material occupies a large ratio, the economical efficiency calculated|required of the surface protection film 22A falls.

The adhesive layer 2 is not particularly limited as long as it is an adhesive layer that can be adhered to the substrate 1, can be easily peeled off after work is completed, and easily stain the adherend surface. When optical durability is considered, an acrylic adhesive is preferable. In addition, the formation method of the adhesion layer 2 and the base material 1 is not specifically limited, It can form also according to a well-known coating method or melt-extrusion method.

As a hardening|curing agent added to the adhesion layer 2, an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound etc. are mentioned as a crosslinking agent which bridge|crosslinks a (meth)acrylate copolymer. Moreover, as a tackifier, a rosin type, a coumaron indene type, a terpene type, petroleum type, a phenol type, etc. are mentioned.

The polymer layer 3 is provided on the upper side of the base material 1, and a release agent such as silicone or fluorine is applied to 1 of an acrylic resin, a polyester resin, a nylon resin, a styrene/acrylonitrile resin, a urethane resin, an epoxy resin, etc. It is obtained by adding to a species or two or more types of high molecular compounds. In addition, UV curing resins and thermosetting resins may be used instead of these polymer compounds.

The polymer layer 3 is preferably 0.003 µm to 3 µm, more preferably 0.02 µm to 1 µm, in order to satisfy a sufficient anti-fouling function and printability.

In addition, the polymer layer 3 has antistatic properties in the layer. As a method of imparting (using, adding) antistatic performance to the polymer layer, various surfactant-type antistatic agents such as cationic antistatic agents, anionic antistatic agents, positive antistatic agents and nonionic antistatic agents, or polyaniline, polypyrrole , conductive polymers such as polythiophene, conductive fillers, and whiskers are used and added. In the present embodiment, the increase rate of the pulling force can be controlled by adjusting the amount of the curing agent and the amount of the antistatic agent, but increasing the amount of the antistatic agent and decreasing the amount of the curing agent added to the adhesive layer 2 It is preferable at the point that the increase rate of a pulling force can be made small.

The polymer layer 3 can also be constituted by mixing the above-described silicone-acrylate-based braid graft polymer with a binder, which is another high-molecular compound, and is a polymer different from the silicone-acrylate-based braid graft polymer. The weight ratio of the binder as a compound is 4:1 to 1:20, preferably 1:1 to 1:12. When the ratio of the silicone-acrylate-based glazed graft polymer is too large, the peeling force by the adhesive tape becomes too light, and the peeling operation of the surface protection film 22 by the cellophane adhesive film also arises. Conversely, when the ratio is too small, the water repellency and dirt-preventing performance are insufficient, and there is a possibility of causing delamination in the luminance improving film 21. Therefore, it is necessary to appropriately adjust the amount of the mold release agent added to the high molecular compound.

In addition, the polymer layer 3 may have an antistatic layer provided between the polymer layer 3 and the base material 1 other than the structure having antistatic properties in the layer. As the antistatic layer, various surfactant-type antistatic agents such as cationic antistatic agents, anionic antistatic agents, amphoteric antistatic agents and nonionic antistatic agents, or binders such as polyester resins and acrylic resins can be used. . Moreover, what disperse|distributed conductive polymers, such as polyaniline, polypyrrole, and polythiophene, an electrically conductive filler, and a whisker in a binder can also be used. Moreover, the conductive compound which consists of a resin which has a phosphoric acid group or a phosphate group, and the polymer which has an oxazoline group can also be used for the polymer compound called acrylic type, polyester type, and polyurethane type. In the formation of the antistatic layer on the substrate, the above substance is dissolved in an organic solvent or the like to make a coating solution, and can be formed by using any known coating method, for example, a gravure coating method, a reverse coating method, a roll coating method, or the like. .

Moreover, it can form also according to the melt-extrusion method.

Moreover, in the polarizing plate 50 in this embodiment, the adhesive layer 51 is provided in the lower surface of the protective film 11. As shown in FIG. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 51 should just satisfy various characteristics (transparency, durability, reworkability, etc.) used in the optical film, for example, having (meth)acrylic acid ester as a main component, and a smaller amount , an acrylic resin having a glass transition temperature (Tg) of 0° C. or less, which is formed by radical polymerization of an acrylic monomer composition containing a (meth)acrylic monomer having a functional group in the presence of a polymerization initiator, and an acrylic pressure-sensitive adhesive containing a crosslinking agent is used.

The surface protection film thus obtained has a pulling force of 10.0 N/25 mm or less after irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 in the UVB region (280 nm to 350 nm), preferably It is 8.0 N/25 mm or less, More preferably, it is 7.0 N/25 mm or less, More preferably, it is 5.0 N/25 mm or less. The surface protection film obtained in this way has a peeling force after irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 in the UVB region (280 nm to 350 nm), preferably 3.0 N/25 mm or less, More preferably, it is 1.0 N/25 mm or less, More preferably, it is 0.5 N/25 mm or less, Especially preferably, it is 0.2 N/25 mm or less, More preferably, it is 0.01 N/25 mm or more. The irradiation intensity at this time can be 500 mW/cm<2>. By making peeling force into 0.01 N/25 mm or more, it can prevent that a surface protection film peels from a brightness improvement film during conveyance.

Moreover, before and after irradiating the active energy ray whose accumulated light amount is 8000 mJ/cm<2>, the increase rate of a pulling force is less than 700 %, Preferably it is 600 % or less. It is preferable that it is 10 % or less, and, as for the transmittance|permeability in wavelength 190nm of a surface protection film, it is more preferable that it is 5 % or less at the point that the increase rate of pulling force can be made small.

As for the polarizing plate of this invention, it is preferable that the edge surface is grind|polished. By grinding|polishing, the dimensional accuracy of the outer shape of a polarizing plate can be improved, and the crack of a polarizer can be prevented further. On the other hand, the aspect-ratio of the surface of the end surface of the end surface of the brightness improving film in a polarizing plate becomes large especially by the grinding|polishing process, and when the surface protection film is peeled off after irradiation with an active energy ray in that state, delamination of the brightness improving film becomes easy to occur. There are cases. ADVANTAGE OF THE INVENTION According to this invention, even if the aspect-ratio (Str) of the surface in the end surface of a brightness improving film is 0.25 or more or 0.28 or more, delamination can be suppressed effectively, for example. That is, according to this invention, the improvement of the dimensional accuracy of a polarizing plate, crack prevention of a polarizer, and suppression of delamination can be made compatible.

In order to perform such a grinding|polishing process, the apparatus of international publication 2011/040636 can be used, for example. The device has a rotating body and a plurality of cutting edges provided on a disk-shaped mounting surface perpendicular to the rotation axis of the rotating body, and by bringing the cutting edges into contact with the end face of the polarizing plate while rotating the rotating body, the end face of the polarizing plate to be polished.

In this embodiment, in order to bring the aspect ratio (Str) of the surface into a predetermined range, it is preferable to increase the number of cutting edges and decrease the rotational speed of the rotating body, for example, the number of cutting edges is 3 or more. and preferably 5 or more, and the rotational speed of the rotating body is, for example, 10000 rpm or less, preferably 6000 rpm or less, and more preferably 5000 rpm or less.

Moreover, from the point that generation|occurrence|production of delamination can be suppressed more, when laminating|stacking and grinding|polishing a polarizing plate, it is preferable to make the end surface of a polarizing plate contact with respect to the center part in the said disk-shaped installation surface.

On the opposite side of the liquid crystal cell (not shown) to which the polarizing plate 50 was bonded in the adhesive layer 51, a polarizing plate of the same kind or a well-known polarizing plate can be laminated|stacked. Further, the polarizing plate 50 provided with the pressure-sensitive adhesive layer 51 is preferably disposed on the back side (back light side) in the liquid crystal display device, and the surface protection film 22 side is disposed so that the back light side is more desirable.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples. In the examples, "%" and "parts" expressed in terms of content or usage are based on weight unless otherwise noted.

[How to create a sample]

(End face treatment)

The end surface treatment was performed using the apparatus of international publication 2011/040636.

A plurality of polarizing plates 50 are polymerized, and the laminated film is sandwiched by a pair of resin-made clamping members from the outer side of the outermost both film surfaces, and a rotating blade is placed on the circumferential surface of the assembly of the laminated film. was made to face the blade surface, and the peripheral surface of the assembly of the laminated film was finished-cut for each peripheral surface of the clamping member by the rotary blade. At this time, the rotational speed of the rotating body was 4800 rpm.

(Active energy ray irradiation)

Measuring instrument: [Fusion UV Systems Co., Ltd. Fusion UV B2-006]

Conveyor speed: 10 m/min, height: 50 mm, light intensity: 100%, valve: D valve, with respect to the polarizing plate 50 bonded to soda glass, from the surface protection film side, UVB region (280 nm to 315) nm), an active energy ray having an irradiation intensity of 500 mJ/cm 2 was irradiated so that the accumulated light amount was 8000 mJ/cm 2 .

[Assessment Methods]

(pull force)

Measuring device: Using [Shimadzu Corporation Autograph AGS-50NX], peeling width: 25 mm, peeling angle: 180 °, peeling speed 300 mm/min, the surface protection film 22 from the brightness improving film 21 A peeling test for peeling was performed. 2 : is a figure which shows the relationship between the distance and force at the time of pulling the surface protection film 22 from the brightness improvement film 21. As shown in FIG. As shown in FIG. 2, although a large force is required for pulling in the initial stage at the time of peeling the surface protection film 22 from the brightness enhancement film 21, after peeling starts, a pulling force becomes small. In this embodiment, the maximum value from the starting point until the surface protection film 22 peels off 25 mm was made into pulling force, and the force after that was made into peeling force.

・Rising rate of pulling force… The pulling force measured before and after irradiating an active energy ray having an irradiation intensity of 500 mJ/cm 2 so that the accumulated light amount is 8000 mJ/cm 2 in the UVB region was calculated using the following equation to calculate the increase rate.

Ascent rate=[(N1-N0)/N0]×100

Unit: %, N0: pulling force before UV irradiation, N1: pulling force after UV irradiation

3 : is a top view at the time of measuring the pulling force at the time of peeling the surface protection film 22 in the polarizing plate 50 from a brightness improvement film. 4 : is sectional drawing at the time of measuring the pulling force at the time of peeling the surface protection film 22 from a brightness enhancement film. In the peeling test, as shown in FIGS. 3 and 4, the adhesive layer 51 of the polarizing plate 50 which has the brightness improving film 21 cut into strips was bonded to the glass 70, and was performed.

The measurement of the pulling force was performed using 10 samples, and the average value was taken. The measurement of the pulling force was performed before active energy ray irradiation to the polarizing plate 50, and after active energy ray irradiation, respectively. About after active energy ray irradiation, after leaving it to stand in the environment of 25 degreeC and 55 %RH, and cooling the temperature of a sample to 23 degreeC, the pulling force was measured.

(Aspect-ratio of the cross section of the brightness enhancement film 21)

Measuring device: Using [Olympus Co., Ltd. model number: OLS4100], the surface roughness was measured in the ultra-high speed mode at a magnification of 100 times. Each of the two end surfaces used as the extending|stretching direction and perpendicular|vertical direction of the brightness improving film was cut out 3 cm at a time, and the width|variety 5 points|pieces were measured. The larger the aspect ratio, the more uneven irregularities exist in the cross section, which is a rough state. It is thought that the cross section is so uniform that a crack or a defect does not generate|occur|produce, so that an aspect-ratio is small.

[Sample production]

According to the specification shown in FIG. 5, the samples of Examples 1-3, Comparative Examples 1-2, and Reference Examples 1-5 were produced.

[Example 1]

The polarizing plate 50 was produced as follows. First, a polyvinyl alcohol film having a thickness of 60 µm (average degree of polymerization of about 2,400, degree of saponification of 99.9 mol% or more) is uniaxially stretched to about 5 times by dry stretching, and, while maintaining the tension, in pure water at 60°C. After immersion for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine/potassium iodide/water of 0.05/5/100 at 28° C. for 60 seconds. Thereafter, it was immersed in an aqueous solution having a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 at 72° C. for 300 seconds. Then, after washing|cleaning for 20 second with 26 degreeC pure water, it dried at 65 degreeC and obtained the 23-micrometer-thick polarizer in which the iodine adsorption-orientation is carried out to the polyvinyl alcohol film. Next, on one side of this polarizer, 3 parts of carboxyl group-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd.] is dissolved in 100 parts of water, and polyvinyl alcohol which is a water-soluble epoxy resin is dissolved in the aqueous solution. An epoxy adhesive containing 1.5 parts of an amide epoxy additive [trade name "Sumirez Resin (registered trademark) 650 (30)" obtained from Taoka Chemical Co., Ltd., an aqueous solution having a solid content concentration of 30%] is applied, and is transparent As the protective film 11 of (21) (manufactured by 3M, trade name Advanced Polarized Film, Version 3) was bonded. A polarizing plate 50 having a pressure-sensitive adhesive layer 51 was prepared by coating an adhesive on the surface to which the triacetyl cellulose film (protective film 11) was bonded. SAT4038T15-JSL (manufactured by San-Eikaken Co., Ltd.), which is a surface protection film 22 having a base material of 38 µm in thickness, a biaxially stretched polyester film, and an adhesive layer having a thickness of 15 µm, containing a curing agent and an antistatic agent The enhancement film 21 was bonded to the bonded surface through the pressure-sensitive adhesive. The transmittance|permeability with respect to the said active energy ray of wavelength 190nm of this surface protection film 22 was 5 % or less.

The polarizing plate 50 which has the produced brightness improvement film 21 was laminated|stacked, and end surface grinding|polishing was performed in the said conditions. The aspect-ratio of the cross section of the brightness improving film 21 after this end surface grinding|polishing was Str=0.30. This sample was irradiated with an active energy ray having an accumulated light amount of 8000 mJ/cm 2 . After adhering the adhesive seal 71 for peeling the surface protection film 22 to the surface protection film 22, the edge part of the one side (the right side of FIG. 3 and FIG. 4) of the adhesive seal 71 is the other side. The surface protection film 22 was pulled by pulling (the left side of FIGS. 3 and 4), and the pulling force at the time of peeling from the brightness improvement film 21 was measured. The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film was 4.8 N/25 mm.

In addition, the pulling force before irradiation of an activation energy ray was 0.77 N/25 mm.

[Example 2]

Samples were prepared in the same procedure as in Example 1 and subjected to the same treatment, but in the surface protection film 22 for protecting APF-V3, the substrate is a biaxially stretched polyester film having a thickness of 38 µm, and the adhesive layer has a thickness of 22 As µm, SAT4538TF-JSL (manufactured by San-Eikaken Co., Ltd.) containing a curing agent and an antistatic agent was used. The aspect-ratio of the cross section of the brightness enhancement film 21 was Str=0.30, and the pulling force at the time of peeling the surface protection film 22 from the brightness enhancement film 21 was 6.2 N/25 mm. The transmittance|permeability with respect to the said active energy ray with a wavelength of 190 nm of this surface protection film 22 was 5 % or less.

[Example 3]

Samples were prepared in the same procedure as in Example 1 and subjected to the same treatment, but in the surface protection film 22 for protecting APF-V3, the substrate is a biaxially stretched polyester film having a thickness of 38 µm, and the adhesive layer has a thickness As 22 m, SAT4238TF-JSL (manufactured by San-Eikaken Co., Ltd.) containing a curing agent and an antistatic agent was used. The aspect-ratio of the cross section of the brightness enhancement film was Str=0.30, and the pulling force at the time of peeling the surface protection film 22 from the brightness enhancement film 21 was 8.2 N/25 mm. The transmittance|permeability with respect to the said active energy ray with a wavelength of 190 nm of this surface protection film 22 was 5 % or less.

[Comparative Example 1]

Samples were prepared in the same procedure as in Example 1, and the same treatment was performed, but in the surface protection film for protecting APF-V3, the substrate was a biaxially stretched polyester film with a thickness of 38 µm, and the adhesive layer had a thickness of 20 µm. AS3-304 (manufactured by Fuji Morikogyo Co., Ltd.) was used as the surface protection film 22 shown in FIG. The aspect-ratio of the cross section of the brightness enhancement film 21 was Str=0.30, and the pulling force at the time of peeling a surface protection film from the brightness enhancement film 21 was 12.0 N/25 mm. The transmittance|permeability with respect to the said active energy ray with a wavelength of 190 nm of this surface protection film 22 was 5 % or less.

[Comparative Example 2]

Although samples were prepared in the same procedure as in Example 1 and subjected to the same treatment, the surface protection film for protecting APF-V3 has the same structure as the surface protection film 22A used in Comparative Example 1, and the substrate has a thickness of 38 µm. It is a phosphorus biaxially stretched polyester film, and AS3-501 (made by Fuji Morikogyo Co., Ltd.) was used whose adhesive layer is 15 micrometers in thickness. AS3-501 is different from AS3-304 in thickness and type of adhesive. The aspect-ratio of the cross section of the brightness enhancement film was Str=0.30, and the pulling force at the time of peeling a surface protection film from the brightness enhancement film 21 was too large, and it was impossible to measure. The surface protection film 22 had a transmittance of 5% or less with respect to the active energy ray having a wavelength of 190 nm.

[Reference Example 1]

Although the sample was created in the procedure similar to Example 1 and the same process was implemented, an active energy ray was not irradiated. The aspect-ratio of the cross section of the brightness improvement film 21 after edge surface grinding|polishing was Str=0.30. The pressure-sensitive adhesive layer 51 of the polarizing plate 50 having the brightness enhancing film 21 cut into strips was bonded to the glass 70 . The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film 21 was 0.77 N/25 mm.

[Reference Example 2]

Although the sample was created in the procedure similar to Example 2 and the same process was implemented, an active energy ray was not irradiated. The aspect-ratio of the cross section of the brightness improvement film 21 after edge surface grinding|polishing was Str=0.30. The pressure-sensitive adhesive layer 51 of the polarizing plate 50 having the brightness enhancing film 21 cut into strips was bonded to the glass 70 . The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film 21 was 2.6 N/25 mm.

[Reference Example 3]

Although the sample was created in the procedure similar to Example 3 and the same process was implemented, an active energy ray was not irradiated. The aspect-ratio of the cross section of the brightness improvement film 21 after edge surface grinding|polishing was Str=0.30. The pressure-sensitive adhesive layer 51 of the polarizing plate 50 having the brightness enhancing film 21 cut into strips was bonded to the glass 70 . The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film 21 was 1.4 N/25 mm.

[Reference Example 4]

Although the sample was created in the procedure similar to the comparative example 1 and the same process was implemented, an active energy ray was not irradiated. The aspect-ratio of the cross section of the brightness improvement film 21 after edge surface grinding|polishing was Str=0.30. The pressure-sensitive adhesive layer 51 of the polarizing plate 50 having the brightness enhancing film 21 cut into strips was bonded to the glass 70 . The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film 21 was 1.2 N/25 mm.

[Reference Example 5]

Although the sample was created in the procedure similar to the comparative example 2 and the same process was implemented, an active energy ray was not irradiated. The aspect-ratio of the cross section of the brightness improvement film 21 after edge surface grinding|polishing was Str=0.30. The pressure-sensitive adhesive layer 51 of the polarizing plate 50 having the brightness enhancing film 21 cut into strips was bonded to the glass 70 . The pulling force at the time of peeling the surface protection film 22 from the brightness improvement film 21 was 7.0 N/25 mm.

7 : is a figure which shows the relationship between the said pulling force and the interlayer peeling incidence rate in the brightness improving film 21. As shown in FIG. As shown in FIG. 7 , it was confirmed that the higher the pulling force, the higher the rate of delamination between the layers. In this embodiment, as shown in FIG. 5, the case where the delamination incidence rate was 0% to 10% or less was evaluated as ○, the case where it was more than 10% and 20% or less was evaluated as △, and the case where it exceeded 20% was evaluated as ×.

On the other hand, when active energy ray irradiation was performed, when the pulling force exceeded 10.0 N/25 mm, or when the increase rate of the pulling force was 700% or more, the delamination generation rate was x, but the pulling force was 10.0 N/ It was 25 mm or less, and when the increase rate of the pulling force was less than 700%, it was confirmed that the delamination generation rate was a good result as ○ or △.

As mentioned above, although preferred embodiment which concerns on this invention was described referring an accompanying drawing, it goes without saying that this invention is not limited to this example. The various shapes, combinations, etc. of each structural member shown in the above-mentioned example are an example, In the range which does not deviate from the main point of this invention, various changes are possible based on a design request etc.

10… Polarizing film (absorptive polarizing film), 20... optical film, 21 ... luminance enhancement film, 22 . . . surface protection film, 50... Polarizer

Claims (8)

An optical film comprising a surface protection film and a brightness improving film having an aspect ratio (Str) of 0.25 or more on the surface in an end surface,
After irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 , the pulling force required for peeling the surface protection film from the luminance enhancing film is 7.0 N/25 mm or less,
An optical film having a rate of increase of the pulling force of less than 700%. An optical film comprising a surface protection film and a brightness improving film having a thickness of 50 µm or less and an aspect ratio (Str) of 0.25 or more on the surface at the end surface,
After irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 , the pulling force required for peeling the surface protection film from the luminance enhancing film is 10.0 N/25 mm or less,
An optical film having a rate of increase of the pulling force of less than 700%. An optical film comprising a surface protection film and a luminance enhancing film having a surface aspect ratio (Str) of 0.25 or more in an end surface, the end surface being polished,
After irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 , the pulling force required for peeling the surface protection film from the luminance enhancing film is 10.0 N/25 mm or less,
An optical film having a rate of increase of the pulling force of less than 700%. An optical film comprising a surface protection film and a brightness improving film having an aspect ratio (Str) of 0.25 or more on the surface in an end surface,
After irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 , the pulling force required for peeling the surface protection film from the luminance enhancing film is 10.0 N/25 mm or less,
An optical film having a rate of increase of the pulling force of less than 700%. The peeling force required when peeling the said surface protection film from the said luminance improving film after irradiating the active energy ray whose accumulated light amount is 8000 mJ/cm<2> is 0.11 N in any one of Claims 1-4 in any one of Claims 1-4 /25 mm or less optical film. The optical film according to claim 5, wherein the increase rate of the peeling force required for peeling the surface protection film from the luminance enhancing film after irradiating an active energy ray having an accumulated light amount of 8000 mJ/cm 2 is 95% or less. The optical film according to any one of claims 1 to 4, wherein the surface protection film has a transmittance of 5% or less with respect to the active energy ray having a wavelength of 190 nm. The polarizing plate which has the optical film in any one of Claims 1-4, and a polarizing film.

Images