KR20230109565A - Surface treated film - Google Patents

Abstract

The present invention provides a surface treatment film in which breakage is suppressed while having a base layer having a small thickness.
The surface treatment film has a substrate layer having a thickness of less than 20 μm, a coating layer formed on the surface of the substrate layer, and a first end portion having a tear strength of 0.5 N or more at a temperature of 23° C. and a relative humidity of 55%.

Description

Surface treatment film {SURFACE TREATED FILM}

The present invention relates to a surface treatment film, and further relates to a polarizing plate provided with a surface treatment film and a method for producing the polarizing plate.

As an optical film used in display devices such as a liquid crystal display device and an organic EL display device, a surface treatment film in which a coating film such as a retardation layer or a hard coat layer is formed by coating a resin composition on the surface of a base material layer such as a resin film is known. There is (for example, Patent Documents 1 and 2, etc.).

Patent Document 1: Japanese Unexamined Patent Publication No. 2020-54939 Patent Document 2: Japanese Unexamined Patent Publication No. 2011-59154

In recent years, reducing the thickness of optical films used in display devices has been demanded. Accordingly, it is required to reduce the thickness of the substrate layer included in the surface treatment film. The surface treatment film in which the coating film was formed in the base material layer with a small thickness sometimes broke at the edge part at the time of conveyance.

An object of the present invention is to provide a surface treatment film having a substrate layer having a small thickness and suppressed in breakage, a polarizing plate provided therewith, and a method for producing the polarizing plate.

This invention provides the manufacturing method of the following surface treatment film, a polarizing plate, and a polarizing plate.

[1] a substrate layer having a thickness of less than 20 μm;

A coating layer formed on the surface of the substrate layer;

The first end having a tear strength of 0.5 N or more at a temperature of 23° C. and a relative humidity of 55%

Surface treatment film having.

[2] the first end includes an uncoated region where the coating layer is not formed on the surface of the substrate layer;

The surface treatment film according to [1], wherein the distance from the end of the substrate layer in the uncoated region to the end of the coated layer is 0.6 mm or more.

[3] The surface treatment film according to [1] or [2], wherein the first end portion is formed along a pair of opposite sides of the surface treatment film in plan view.

[4] At a temperature of 23 ° C. and a relative humidity of 55%, by a cross hatch test performed by forming 100 cross hatches on the coated layer of the surface treatment film, 90 or more cross hatches remain on the base layer, [1] The surface treatment film according to any one of [3].

[5] The surface treatment film according to any one of [1] to [4], wherein the substrate layer is a cyclic olefin resin film.

[6] The surface treatment film according to any one of [1] to [5], wherein the coating layer is a cured product layer of a composition containing an ultraviolet curable resin.

[7] The surface treatment film is a long body,

The surface treatment film according to any one of [1] to [6], wherein the first end portion is formed at both ends of the surface treatment film in the width direction.

[8] A polarizing plate comprising: the surface-treated film according to any one of [1] to [7]; and a linear polarizing layer.

[9] A method for producing the polarizing plate according to [8],

A step of preparing a laminate having the surface treatment film and a protection film laminated so as to be peelable on the substrate layer side of the surface treatment film;

A step of conveying the surface treatment film obtained by peeling the protective film from the laminate;

Step of laminating the surface treatment film obtained in the step of conveying and the linear polarizing layer

Including, the manufacturing method of the polarizing plate.

ADVANTAGE OF THE INVENTION According to this invention, the surface treatment film which fracture|rupture was suppressed can be provided while having a base material layer with a small thickness.

1 is a plan view schematically showing a surface treatment film according to an embodiment of the present invention.
FIG. 2 is a XX′ cross-sectional view of FIG. 1 .
Fig. 3 is a plan view schematically showing a sample piece used for measuring tear strength.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described referring drawings, this invention is not limited to the following embodiment. All of the drawings below are shown to aid understanding of the present invention, and the size or shape of each component shown in the drawings does not necessarily match the size or shape of the actual component.

(surface treatment film)

1 is a plan view schematically showing a surface treatment film according to an embodiment of the present invention. FIG. 2 is a XX' sectional view of FIG. 1 .

As shown in FIGS. 1 and 2 , the surface treatment film 1 includes a substrate layer 11 having a thickness of less than 20 μm, a coating layer 12 formed on the surface of the substrate layer 11, and a temperature of 23 ° C. and a first end (10) having a tear strength of at least 0.5 N at 55% relative humidity.

In the surface treatment film 1, the base material layer 11 and the coating layer 12 are in direct contact. The surface treatment film 1 has a coated region 22 in which the coated layer 12 is formed on the surface of the base layer 11, and a coated region 22 in which the coated layer 12 is not formed on the surface of the base layer 11. It may have the uncoated area|region 21, and may have the coated area|region 22, and may not have the uncoated area|region 21.

The first end 10 includes an end that is a tear start position when tearing the surface treatment film 1, and at least a part of the side 15 on which the end is located in a planar view of the surface treatment film 1 It is an area formed by As shown in FIG. 1, the 1st end part 10 may be the area|region formed along the whole side 15.

The 1st edge part 10 should just be formed along part or all of at least 1 side of the sides in planar view of the surface treatment film 1, and may be formed along a part or all of two or more sides. It is preferable that the 1st edge part 10 is formed along the pair of sides 15 and 15 which oppose in planar view of the surface treatment film 1. As shown in FIGS. 1 and 2 , when the surface treatment film 1 is a long body, the first end 10 is formed at both ends of the surface treatment film 1 in the width direction W. desirable.

The tear strength of the first end portion 10 at a temperature of 23°C and a relative humidity of 55% is 0.5 N or more, preferably 0.8 N or more, may be 1.0 N or more, may be 1.2 N or more, or may be 1.5 N or more. , may be 1.7 N or more, may be 1.8 N or more, and is usually 5.0 N or less, may be 4.5 N or less, or may be 4.0 N or less.

The tear strength of the first end portion 10 is determined by moving the surface treatment film 1 in a direction crossing the side 15 where the end is located from the end of the surface treatment film 1 as a tear start position. It is tear strength at the time of tearing, and can be measured by the method described in the Example mentioned later. As shown in FIG. 1 , when the edge 15 is straight, the tearing direction is a direction orthogonal to the edge 15 . You may say that the tearing direction is the direction in which the crack propagates at the time of tearing.

The method of forming the 1st end part 10 which has said tear strength in the surface treatment film 1 is not specifically limited. For example, a method of forming the first end 10 to include an uncoated region 21 on the surface of the base layer 11 where the coated layer 12 is not formed, and the base layer on which the first end 10 is formed. A method of making the thickness of the end portion over the entire end portion of (11) larger than the thickness of the base layer 11 other than the end portion, using a coating material containing a solvent that does not cause deterioration of the base layer 11 Methods, such as the method of forming the coating layer 12 in the 1st end part 10, and the method of forming the coating layer 12 with high toughness in the 1st end part 10, are mentioned.

When the first end portion 10 includes the uncoated area 21, the first end portion 10 may include the coated area 22 or may not include the coated area 22. When the first end portion 10 includes the uncoated region 21, the distance L from the end of the substrate layer 11 to the end of the coated layer 12 at the first end portion 10 is 0.6 mm or more. It is preferably 0.8 mm or more, 1.0 mm or more, 1.5 mm or more, 5.0 mm or more, or 5.5 mm or more. The upper limit of the distance L is not particularly limited, but may be, for example, 50 mm or less, or 40 mm or less. The distance L is the position of the center of the extension direction of the 1st end part 10 of the sample taken from the surface treatment film 1, and the position of 1 cm in both directions (left-right direction) from this center position along the extension direction. It means the average value of the shortest distance from the end of the base material layer 11 to the end of the coating layer 12 at the position of a total of 3 points with and, and can be determined by the method described in the examples described later. Samples in the case where the surface treatment film 1 is a long body are taken from both ends in the longitudinal direction of the long body, and the average values of the shortest distances determined in the above procedure for each of the two samples taken are averaged again. Let it be the distance L. When the surface treatment film 1 is a single sheet, it is sampled at an arbitrary position.

When the distance L is within the above range, it becomes easy to adjust the tear strength of the first end portion 10 within the above range. When the surface treatment film 1 is a long body, etc., storage and transportation are performed in the state of a roll body in which the surface treatment film 1 is wound up in a roll shape. In the roll body, the difference between the thickness of the coated region 22 of the surface treatment film 1 and the thickness of the uncoated region 21, and behavior such as shrinkage and expansion occurring during storage of the surface treatment film 1 Owing to a difference or the like, the end face of the roll body may be bent. The surface treatment film 1 unrolled from the roll body whose end face was bent may also be deformed. In the surface treatment film 1, when the distance L is within the above range, a roll body wound in a good shape can be formed, and deformation of the surface treatment film 1 unwound from the roll body can be suppressed. there is.

Because the surface treatment film 1 has the first end portion 10, the first end portion 10 intersects the side 15 when conveying the surface treatment film 1 in manufacturing a polarizing plate described later, for example. It is possible to suppress breakage of the first end portion 10, such as tearing in the direction of. On the other hand, in the case of a surface-treated film having an end portion having a tear strength of less than 0.5 N, the end portion is likely to be broken at the time of transportation or the like. This is because, as in the case where the thickness of the base layer 11 is less than 20 μm, in the surface treatment film 1 where the thickness of the base layer 11 is small, it is difficult to alleviate the impact by the base layer 11, and the base layer 11 ) It is estimated that this is because the coated area 22 became weak because the hard coated layer 12 on the surface is easily damaged. It is considered that the weakened region is likely to break when subjected to an external force or deformed. Since the surface treatment film 1 is easily subjected to external force or deformed at the end during conveyance or the like, in the surface treatment film 1 having the first end 10 having a tear strength of 0.5 N or more, the first end It is estimated that breakage of (10) can be suppressed.

In the surface treatment film 1, it is preferable that 90 or more cross hatches remain on the substrate layer 11 by a cross hatch test performed by forming 100 cross hatches in the coating layer 12, and 95 or more cross hatches remain. It is more preferable, and it is even more preferable that 100 remain. It is thought that such surface treatment film 1 is excellent in the adhesiveness of the base material layer 11 and the coating layer 12. In the surface treatment film 1 excellent in adhesiveness, it is considered that the above-mentioned breakage easily occurs at one end when subjected to an external force or deformed. Therefore, by forming the first end portion 10 with respect to the surface treatment film 1 excellent in adhesion between the substrate layer 11 and the coating layer 12, the first end portion of the surface treatment film 1 ( 10) can be effectively suppressed. In the cross hatch test, 100 cross hatches of 1 mm square were engraved on the surface of the coated layer 12 of the surface treatment film 1 at a temperature of 23° C. and a relative humidity of 55%, and the adhesive tape adhered to the cross hatches was peeled off. It is a test performed by doing, and can be conducted by the method described in the Examples described later.

The surface treatment film 1 may be a single sheet or may be a long body that can be conveyed continuously. In this specification, a long body refers to a surface treatment film having a length of, for example, 30 m or more and 15000 m or less. When the surface treatment film 1 is a long body, it is preferable that the 1st end part 10 is formed in both ends of the width direction W, as shown in FIG.

The surface treatment film 1 may have at least one or more functions such as hard coat properties, anti-glare properties, antireflection properties, antistatic properties, and antifouling properties. These characteristics can be imparted by the coating layer 12 . The surface treatment film 1 can impart the above characteristics and the like to an adherend by bonding to the surface of an adherend such as a linear polarizing layer described later. As for the surface treatment film 1, it is preferable that the base material layer 11 side is bonded to the adherend.

(base layer)

The substrate layer 11 is used to cover the surface of an adherend and to support the coating layer 12 . It is preferable that the base material layer 11 is a resin film, and it is preferable that it is a transparent resin film. As the transparent resin film, for example, a film formed using a known resin in the field of an optical film or the like can be used. As a transparent resin film, Polyolefin films, such as polyethylene, a polypropylene, and an ethylene-propylene copolymer; cyclic olefin resin films composed of norbornene-based polymers and the like; polyester films composed of polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; (meth)acrylic resin films made of poly(meth)acrylic acid ester and the like; cellulose resin films such as triacetyl cellulose; polycarbonate film; polyamide films such as nylon and aromatic polyamide; A polyimide film etc. are mentioned. The transparent resin film is preferably at least one of a cyclic olefin resin film, a polyester film, and a (meth)acrylic resin film, and more preferably a cyclic olefin resin film. A "(meth)acryl" represents at least one of an acryl and methacryl. The same applies to "(meth)acrylate" and the like.

The thickness of the substrate layer 11 is less than 20 μm, may be 18 μm or less, may be 15 μm or less, may be 13 μm or less, usually 1 μm or more, and may be 5 μm or more. Although the edge part of the surface treatment film provided with the base material layer 11 whose thickness is in the said range is easy to break at the time of conveyance, according to this invention, thickness reduction and prevention of breakage can be made compatible.

(coating layer)

The coating layer 12 may be a layer for imparting at least one or more specific functions such as hard coat properties, antiglare properties, antireflection properties, antistatic properties, and antifouling properties to the surface treatment film 1 . Examples of the coating layer 12 include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer.

The coated layer 12 can be formed by coating the base material layer 11 with a coating material for forming the coated layer 12 . As the coating method of the coating material, a known method can be used without particular limitation, but die coating or gravure coating is preferred. From the viewpoint of coating precision, gravure coating is more preferable.

A method of coating the uncoated region 21 and the coated region 22 of the surface treatment film 1 using, for example, a gravure roll subjected to concavo-convex processing according to the width of the coated region 22; It can be formed by a method of coating the gravure roll and the base layer 11 so that they do not come into contact by attaching a film or forming a nail to the surface of the gravure roll in the portion where the uncoated region 21 is formed. there is. The width of the coating region 22 can be adjusted by adjusting the surface condition of the gravure roll as described above. The width of the uncoated region 21 can be adjusted by the viscosity of the coating material used to form the coated region 22 . When manufacturing the surface treatment film 1, it is preferable to adjust the viscosity of the coating material so that the fluctuation|variation of the width of the uncoated area|region 21 may become less than 0.5 mm.

The viscosity of the coating material is, for example, 1 mPa·s or more and 150 mPa·s or less at a temperature of 25°C, preferably 3 mPa·s or more and 100 mPa·s or less, more preferably 5 mPa·s or more and 50 mPa·s or less. It is less than s. If the viscosity is too small, there is a possibility that coating unevenness may become remarkable, and if the viscosity is too large, there is a possibility that adjustment of the film thickness may become difficult. When the viscosity is 1 mPa·s or more and 150 mPa·s or less, it tends to be easy to adjust the coating film thickness. The viscosity may be a value measured by a Brookfield viscometer (B-type viscometer, manufactured by Brookfield Co.).

As the coating material, a composition containing a curable compound; and compositions containing resins other than curable compounds. The coating material is a filler such as organic fine particles or inorganic fine particles, an antistatic agent, an antifouling agent, and a colorant in addition to the above-mentioned curable compound and resin in order to suitably form the function and/or the coating layer 12 that the coating layer 12 has. , a ultraviolet absorber, an antioxidant, a light stabilizer, a flame retardant, a viscosity modifier, a crosslinking agent, a coupling agent, a leveling agent, an antifoaming agent, a solvent, and the like may be included.

Examples of the curable compound contained in the composition containing the curable compound include active energy ray curable resins such as ultraviolet curable resins and electron beam curable resins; thermosetting resins; monomers having polymerizable groups such as a (meth)acryloyl group and a vinyl group; Oligomers having a polymerizable group, and the like are exemplified. As resins other than a curable compound, a thermoplastic resin etc. are mentioned.

The coated layer 12 is preferably a cured product layer of a composition containing an active energy ray-curable resin, and more preferably a cured product layer of a composition containing an ultraviolet curable resin. It is preferable that the composition containing ultraviolet curable resin is an acrylic resin composition containing a (meth)acrylate monomer and/or a (meth)acrylic resin. As the (meth)acrylate monomer and/or the (meth)acrylic resin, a polyfunctional (meth)acrylate, a polyfunctional urethanated (meth)acrylate, a polyol (meth)acrylate, and optionally two hydroxyl groups and a curable mixture containing a (meth)acrylic polymer having an alkyl group contained above.

As the polyfunctional (meth)acrylate, for example, di- or tri-(meth)acrylate of trimethylolpropane, tri- or tetra-(meth)acrylate of pentaerythritol, having at least one hydroxyl group in the molecule ( and polyfunctional urethanated (meth)acrylates which are reaction products of meth)acrylate and diisocyanate. These polyfunctional (meth)acrylates may be used independently, respectively, or may be used in combination of two or more.

Polyfunctional urethanated (meth)acrylates are prepared using, for example, (meth)acrylic acid and/or (meth)acrylic acid esters, polyols and diisocyanates. Specifically, by preparing hydroxy (meth)acrylate having at least one hydroxyl group in the molecule from (meth)acrylic acid and/or (meth)acrylic acid ester and polyol, and reacting this with diisocyanate, polyfunctional Urethanelated (meth)acrylates can be prepared. The multifunctional urethanated (meth)acrylate produced in this way has a function as the ultraviolet curable resin. In its production, (meth)acrylic acid and/or (meth)acrylic acid ester may be used individually by one type or in combination of two or more types, and polyol and diisocyanate may also be used in the same way, even if one type is used. It is good, and you may use in combination of 2 or more types.

As the (meth)acrylic acid ester used when forming the polyfunctional urethanized (meth)acrylate, a chain or cyclic alkyl ester of (meth)acrylic acid can be used, and specific examples thereof include methyl (meth)acrylate Alkyl (meth)acrylates, such as ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and butyl (meth)acrylate; Cycloalkyl (meth)acrylates, such as cyclohexyl (meth)acrylate, etc. are mentioned.

The polyol used when forming the polyfunctional urethanized (meth)acrylate is a compound having at least two hydroxyl groups in the molecule, and specific examples thereof include ethylene glycol, propylene glycol, 1,3-propanediol, and diethylene Glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl -1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol ester of hydroxypivalic acid, cyclohexanedimethylol, 1,4-cyclohexanediol, spiroglycol, tricyclodecanedimethylol , hydrogenated bisphenol A, ethylene oxide added bisphenol A, propylene oxide added bisphenol A, trimethylolethane, trimethylolpropane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, Tripentaerythritol, glucose, etc. are mentioned.

The diisocyanate used when forming the polyfunctional urethanated (meth)acrylate is a compound having two isocyanato groups (-NCO) in the molecule, and various aromatic, aliphatic or alicyclic diisocyanates can be used. , Specific examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3, 3'-dimethyl-4,4'-diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and nuclear hydrogenation products of diisocyanates having aromatic rings among them; can be heard

The (meth)acrylic polymer having an alkyl group containing two or more hydroxyl groups has an alkyl group containing two or more hydroxyl groups in one constituent unit, and its specific example is 2,3-dihydroxypropyl (meth)acrylic polymer. ) A polymer containing acrylate as a structural unit, a polymer containing 2-hydroxyethyl (meth)acrylate as a structural unit together with 2,3-dihydroxypropyl (meth)acrylate, and the like are exemplified. .

A composition containing a curable compound may contain a polymerization initiator in addition to the curable compound. Examples of the polymerization initiator include photopolymerization initiators and radical polymerization initiators, and known polymerization initiators can be used.

When the coated layer 12 is a hard coat layer, the coated layer 12 has a function of improving the surface hardness of the substrate layer 11 and can improve surface scratch resistance. The hard coat layer is a pencil hardness test (surface-treated film) specified in JIS K 5600-5-4: 1999 "General test methods for paints-Part 5: Mechanical properties of coating films-Part 4: Scratch hardness (pencil method)" is placed on a glass plate and measured), it is preferable to show a value of 8B or harder, and it may be 5B or harder. It is preferable that the coating layer 12 is a hard coat layer.

When the coated layer 12 is an anti-glare layer, the coated layer 12 may have functions such as improving visibility, suppressing the reflection of external light, and reducing moiré (interference fringes). The anti-glare layer may have fine concavo-convex shapes on its surface. Fine concavo-convex shapes can be formed by adding a filler to the anti-glare layer or by applying fine embossing to the surface.

When the coating layer 12 is an antireflection layer, the coating layer 12 may have a function of suppressing reflection of external light. The antireflection layer may be a layer having a refractive index smaller than that of the substrate layer 11, and may contain fine particles, for example.

When the coating layer 12 is an antistatic layer, the coating layer 12 may have a function of suppressing generation of static electricity and the like. The antistatic layer may contain an antistatic agent (eg, a conductive material).

When the coating layer 12 is an antifouling layer, the coating layer 12 can impart functions such as water repellency, oil repellency, cold resistance and antifouling properties to the surface treatment film 1 . The antifouling layer may contain an antifouling agent such as a fluorine-containing organic compound such as fluorocarbon, perfluorosilane, or a polymer compound thereof.

The thickness of the coating layer 12 may be, for example, 1 nm or more, 10 nm or more, 50 nm or more, 500 nm or more, 1 μm or more, 15 μm or less, or 10 μm. It may be less than or equal to 5 μm, may be less than 5 μm, or may be less than or equal to 4 μm.

In addition, when the thickness of the substrate layer 11 is less than 20 μm, the thickness of the coating layer 12 is preferably 3 μm or less, more preferably 2 μm or less. With respect to the thickness of the base layer 11, when the thickness of the coating layer 12 is thick, warping of the end of the base layer is likely to occur due to curing shrinkage. may lead to

(Polarizer)

The polarizing plate of this embodiment has the surface treatment film 1 and a linearly polarizing layer. The polarizing plate may have the surface treatment film 1 on one side or both sides of the linear polarizing layer. In the case of having the surface treatment film 1 on both sides of the linear polarization layer, the two surface treatment films 1 may be of the same type or of different types. As for the surface treatment film 1, it is preferable that the base material layer 11 side faces the linear polarization layer.

The polarizing plate may have a bonding layer for bonding the surface treatment film 1 and the linear polarizing layer. The bonding layer is a pressure-sensitive adhesive layer or an adhesive layer. When the polarizing plate has a bonding layer, it is preferable that the bonding layer is formed on the substrate layer 11 side of the surface treatment film 1 .

When the polarizing plate has the surface treatment film 1 on one side of the linear polarizing layer, the polarizing plate may have a layer other than the surface treatment film 1 on the other side of the linear polarizing layer. As another layer, a protective layer, a retardation layer, an adhesive layer, etc. are mentioned. The linear polarization layer and other layers may be laminated so as to be in direct contact with each other, or when the other layers are protective layers or retardation layers, they may be laminated via a bonding layer.

(Manufacturing method of polarizing plate)

The manufacturing method of the polarizing plate of this embodiment,

A step of preparing a laminate having a surface treatment film 1 and a protection film laminated so as to be peelable on the substrate layer 11 side of the surface treatment film 1;

A step of conveying the surface treatment film 1 obtained by peeling the protection film from the laminate;

Step of laminating the surface treatment film 1 obtained in the step of conveying and the linear polarizing layer

can include

In the step of preparing, for example, after bonding a protection film to one side of the substrate layer 11, the coating layer 12 is formed on the surface of the substrate layer 11 (surface on the opposite side to the side to which the protection film was bonded). Thus, a laminate can be obtained. The coating layer 12 can be formed by coating a coating material on the side opposite to the protection film side of the substrate layer 11 . As a method of coating the coating material, a known method can be mentioned, and for example, one or more of gravure coating, bar coating, spray coating, spin coating, dip coating, die coating, and inkjet coating can be used. After coating the coating material on the base material layer 11, you may perform processing, such as drying and/or hardening of the curable compound contained in the coating material, depending on the kind of coating material.

In the process of conveying, for example, while conveying the laminate, the protection film is peeled from the laminate, the surface treatment film 1 and the protection film are separated, and these can be conveyed, respectively. A well-known conveyance method can be employ|adopted for conveyance of a laminated body, the surface treatment film 1, and a protection film, For example, conveyance can be carried out using a conveyance roll and/or a conveyance belt. The tension at the time of conveying with the conveying roll can be adjusted so that the film to be conveyed is conveyed without meandering. Tension at the time of conveying with a conveyance roll can be adjusted so that the film conveyed may not break.

In the step of laminating, for example, the side (substrate layer 11 side) exposed by peeling the protection film of the surface treatment film 1 and the linear polarizing layer can be laminated via a bonding layer or the like.

The tear strength of the 1st end part 10 of the surface treatment film 1 exists in the said range. Therefore, in the surface treatment film 1 conveyed in the conveyance step, it is possible to suppress breakage of the first end portion 10, which is easily subjected to external force or deformed. Thereby, a yield can be improved and a polarizing plate can be manufactured.

(linear polarization layer)

The linearly polarized layer has a property of transmitting linearly polarized light having a plane of vibration orthogonal to the absorption axis when unpolarized light is incident therethrough. The linear polarizing layer may be a polyvinyl alcohol-based resin film in which iodine is adsorbed and oriented (hereinafter sometimes referred to as a "PVA-based film"), and a composition containing a compound having absorption anisotropy and liquid crystallinity is applied to the base film. It may be a film containing a liquid crystalline linear polarizing layer formed by application. The compound having absorption anisotropy and liquid crystallinity may be a mixture of a pigment having absorption anisotropy and a compound having liquid crystallinity, or a pigment having absorption anisotropy and liquid crystallinity.

The linear polarizing layer, which is a PVA-based film, is a PVA-based film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, a partially saponified film based on an ethylene-vinyl acetate copolymer, dyeing treatment with iodine, and a stretching treatment. things, etc. If necessary, a washing step may be performed in which the PVA-based film to which iodine is adsorbed and oriented by dyeing treatment is treated with an aqueous solution of boric acid, and thereafter the aqueous solution of boric acid is washed off. A well-known method can be employ|adopted for each process.

The polyvinyl alcohol-based resin (hereinafter sometimes referred to as "PVA-based resin") can be produced by saponifying polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate other than polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the PVA-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The PVA-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The average degree of polymerization of the PVA-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The degree of saponification and average degree of polymerization of the PVA-based resin can be obtained in accordance with JIS K 6726 (1994). When the average degree of polymerization is less than 1000, it is difficult to obtain desirable polarization performance, and when it exceeds 10000, film workability may be poor.

A method for producing a linear polarizing layer that is a PVA-based film is to prepare a base film, apply a resin solution such as a PVA-based resin on the base film, and perform drying to remove the solvent to form a resin layer on the base film. It may also contain the process of doing. Moreover, a primer layer can be formed beforehand in the surface on which the resin layer of a base film is formed. As a base film, the film using the resin material demonstrated as a thermoplastic resin used in order to form the protective film as a protective layer mentioned later can be used. As a material of the primer layer, a resin obtained by crosslinking a hydrophilic resin used in the linear polarization layer may be used.

Subsequently, the amount of solvent such as moisture in the resin layer is adjusted as necessary, and then the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with iodine to adsorb and orient iodine into the resin layer. Next, if necessary, the resin layer in which iodine is adsorbed and oriented is treated with an aqueous solution of boric acid, and thereafter, a washing step of washing off the aqueous solution of boric acid is performed. This produces a resin layer in which iodine is adsorbed and oriented, that is, a PVA-based film serving as a linear polarization layer. A well-known method can be employ|adopted for each process.

The linear polarizing layer produced by the manufacturing method using a base film can be obtained by peeling the base film after laminating a protective layer.

The thickness of the linear polarizing layer, which is a PVA-based film, is preferably 1 μm or more, may be 2 μm or more, may be 5 μm or more, and is preferably 30 μm or less, more preferably 15 μm or less, and may be 10 μm or less. It may be 8 μm or less.

Examples of the film containing the liquid crystalline linear polarization layer include a linear polarization layer obtained by applying a composition containing a pigment having liquid crystallinity and absorption anisotropy, or a composition containing a pigment having absorption anisotropy and a polymerizable liquid crystal onto a base film. can The liquid crystal linear polarization layer may be a cured product of a polymerizable liquid crystal compound and may include an orientation layer. The film containing the liquid crystal linear polarization layer may be a liquid crystal linear polarization layer or may have a laminated structure of a liquid crystal linear polarization layer and a base film. As a base film, the film using the resin material demonstrated as a thermoplastic resin used in order to form the protective film as a protective layer mentioned later is mentioned, for example. As a film containing a liquid crystalline linear polarization layer, the polarization layer of Unexamined-Japanese-Patent No. 2013-33249 etc. is mentioned, for example.

The total thickness of the base film and the linear polarizing layer formed as described above is preferably smaller, but if it is too small, the strength tends to decrease and workability tends to deteriorate, so it is usually 20 μm or less, preferably 5 μm or less. and more preferably 0.5 to 3 μm.

(other floors)

Examples of the protective layer as another layer include a protective film, which is a film formed of a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, water barrier properties, isotropy, and stretchability; and an overcoat layer formed of a composition having excellent solvent resistance, transparency, mechanical strength, thermal stability, shielding properties, and isotropic properties. The protective film is preferably laminated on the linear polarization layer via a bonding layer, and the overcoat layer is preferably laminated so as to directly contact the linear polarization layer.

Specific examples of the thermoplastic resin for forming the protective film include cellulosic resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resin; polysulfone resin; polycarbonate resin; polyamide resins such as nylon and aromatic polyamide; polyimide resin; Polyolefin resins, such as polyethylene, a polypropylene, and an ethylene-propylene copolymer; cyclic polyolefin resins (also referred to as norbornene-based resins) having a cyclo-based and norbornene structure; (meth)acrylic resin; polyarylate resins; polystyrene resin; polyvinyl alcohol resins, and mixtures thereof. The thickness of the protective film is preferably 3 μm or more, more preferably 5 μm or more, more preferably 50 μm or less, and more preferably 30 μm or less.

The overcoat layer can be formed, for example, by applying a material (composition) for forming the overcoat layer on the linear polarization layer. Examples of materials constituting the overcoat layer include photocurable resins and water-soluble polymers, and (meth)acrylic resins, polyvinyl alcohol resins, polyamide epoxy resins, and the like can be used. The thickness of the overcoat layer may be, for example, 0.1 μm or more and 10 μm or less.

The retardation layer as another layer may be a stretched film or may contain a cured material layer of a polymerizable liquid crystal compound. A well-known thing can be used as a stretched film and hardened|cured material layer which comprise a phase difference layer.

An adhesive layer as another layer is an adhesive layer formed using an adhesive composition. A pressure-sensitive adhesive composition or a reaction product of the pressure-sensitive adhesive composition expresses adhesiveness by adhering itself to an adherend such as a display element of a display device, and is referred to as a so-called pressure-sensitive adhesive. In addition, the degree of crosslinking and adhesive strength of the pressure-sensitive adhesive layer formed using the active energy ray-curable pressure-sensitive adhesive composition described later can be adjusted by irradiation with active energy rays.

As the pressure-sensitive adhesive composition, known pressure-sensitive adhesives having excellent optical transparency may be used without particular limitation, and for example, pressure-sensitive adhesive compositions containing base polymers such as acrylic polymers, urethane polymers, silicone polymers, and polyvinyl ether may be used. Moreover, an active energy ray-curable adhesive composition or a thermosetting adhesive composition may be sufficient as an adhesive composition. Among these, a pressure-sensitive adhesive composition having an acrylic resin as a base polymer having excellent transparency, adhesive strength, re-peelability (reworkability), weather resistance, heat resistance, and the like is suitable. The pressure-sensitive adhesive layer is preferably composed of a reaction product of a pressure-sensitive adhesive composition containing a (meth)acrylic resin, a crosslinking agent, and a silane compound, and may contain other components.

In the active energy ray-curable pressure-sensitive adhesive composition, a harder pressure-sensitive adhesive layer can be formed by blending the pressure-sensitive adhesive composition with an ultraviolet curable compound such as a multifunctional acrylate and curing the formed layer by applying ultraviolet rays. . The active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with energy rays such as ultraviolet rays and electron beams. Since the active energy ray-curable pressure-sensitive adhesive composition has adhesiveness even before energy ray irradiation, it adheres to an adherend and has a property of being cured by energy ray irradiation to adjust the adhesion.

If necessary, the pressure-sensitive adhesive composition and the active energy ray-curable pressure-sensitive adhesive composition may contain additives such as antioxidants, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, antistatic agents, and solvents.

(bonding layer)

The bonding layer is a pressure-sensitive adhesive layer or an adhesive layer. As for the adhesive layer, those mentioned above are mentioned. The adhesive layer can be formed by curing the curable component in the adhesive composition. Examples of the adhesive composition for forming the adhesive layer include adhesives other than pressure-sensitive adhesives (pressure-sensitive adhesives), such as water-based adhesives and active energy ray curable adhesives.

Examples of water-based adhesives include adhesives obtained by dissolving or dispersing polyvinyl alcohol resin in water. The drying method in the case of using a water-based adhesive is not particularly limited, but, for example, a method of drying using a hot air dryer or an infrared dryer can be employed.

Examples of active energy ray curable adhesives include solvent-free active energy ray curable adhesives containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Adhesion between layers can be improved by using a non-solvent type active energy ray curable adhesive.

(protection film)

The protection film is laminated on the base material layer 11 side of the surface treatment film 1 so that peeling is possible, and is used in order to cover and protect the surface of the surface treatment film. The protection film may have a multilayer structure in which a resin film and an adhesive layer are laminated, or may be a self-adhesive film having a single layer structure.

As the resin film, for example, a film formed using a known resin in the field of an optical film or the like can be used. Examples of the resin constituting the resin film include polyolefins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene-based polymers; polyvinyl alcohol; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; poly(meth)acrylic acid ester; cellulosic resins such as triacetyl cellulose, diacetyl cellulose and cellulose acetate propionate; polycarbonate; polysulfone; polyethersulfone; polyether ketone; polyphenylene sulfide; Polyphenylene oxide etc. are mentioned.

When the protection film is a self-adhesive film, a film obtained by forming a polypropylene-based resin, a polyethylene-based resin, or the like into a film is exemplified.

Example

Hereinafter, the present invention will be described more specifically by showing examples and comparative examples, but the present invention is not limited by these examples.

[Examples 1 to 10, Comparative Examples 1 and 2, Reference Examples 1 to 3]

As a substrate layer, a cyclic olefin resin film having a thickness shown in Table 1 (hereinafter sometimes referred to as "COP film") was prepared. On one side of the COP film, an acrylic resin composition containing an ultraviolet curable resin was gravure coated to form a coating film so that uncoated regions were formed along a pair of opposing sides (both ends in the width direction). The viscosity of the acrylic resin composition measured by the method described later was 20 mPa·s. After drying the coating film, ultraviolet irradiation was performed, a coating layer as a hard coat layer was formed on the surface of the substrate layer, and a surface treatment film was obtained.

The COP film side of the sample taken from the surface treatment film was bonded to a glass plate, and the center position of the end of the COP film (the end where the coating layer was not formed) in the extension direction and the left-right direction (extension direction) from this center position Determine the shortest distance from the end of the COP film to the coating layer at a total of 3 positions of 1 cm in both directions), and average these to determine the distance from the end of the COP film of the surface treatment film to the coating layer. The distance L between the ends was determined. The shortest distance was determined by acquiring a thickness plot while moving from the end of the COP film of the sample toward the coating layer using a dual mode 3D confocal interference system PLμ2300 (manufactured by Sensofa Japan Co., Ltd.) (lens: 20 pear (EPI 20x)). Table 1 shows the value of the determined distance L1.

The tearing strength was measured in the procedure described later about the end of the surface treatment film at which the uncoated region was formed (substrate layer for Reference Examples 1 and 3). About the surface treatment film obtained by reference examples 1 and 3 other than, the crosshatch test was done by the procedure mentioned later. The results are shown in Table 1.

In addition, a coating layer was formed in the above procedure to obtain a surface-treated film of a long body, except that the substrate layer of a long body was used as the substrate layer. In Reference Examples 1 and 3, a long substrate layer without a coating layer was used. The presence or absence of breakage was confirmed when the long surface treatment film (the long base material layer for Reference Examples 1 and 3) was conveyed with a conveyance roll so that no problems in conveyance such as meandering occurred. The results are shown in Table 1.

[Measurement of tear strength]

Fig. 3 is a plan view schematically showing a sample piece used for measuring tear strength. At the end where the uncoated region of the surface treatment film is formed, the end of the surface treatment film, including the uncoated region 21 and the coated region 22, is 50 in the extending direction of the side where the end of the surface treatment film is located. A rectangular sample piece 31 was cut out so as to have a size of 70 mm in the direction perpendicular to the above side (Fig. 3). Two leads are placed on one side of the sample piece 31 so as to span the side 33 constituting the side of the surface-treated film among the sides of the sample piece 31, the uncoated area 21, and the coated area 22. Tapes (pyolane cloth curing tape green, 50 mm × 25 mm, Y-09-GR, manufactured by Daiyatex) 35, 35 were attached (hereinafter, the side 33 to which the lead tape was attached was referred to as “attached side”). (33)”). Each lead tape 35 is 50 mm in length x 20 mm in width, and a gap of 1 mm is formed between the two lead tapes 35 and 35 at the center of the attachment side 33 of the sample piece 31. , The lead tape 35 was attached to the sample piece 31 so that the width direction was parallel to the attaching side 33 and a range of 10 mm in length from one end was disposed on the sample piece 31. Also on the other side of the sample piece 31, two lead tapes were attached so as to overlap the lead tapes 35 and 35 attached to one side of the sample piece 31. As a result, as shown in FIG. 3, two lead tapes (leads attached to both sides of the sample piece 31) are attached to the attachment side 33 of the sample piece 31 in a planar view of the sample piece 31. The lead tape groups with overlapping tapes) were attached in two sets at intervals (gap) of 1 mm.

Among the ends in the longitudinal direction of the lead tape 35 attached to the sample piece 31, the end on the opposite side to the side attached to the sample piece 31 is placed on the top and bottom of the autograph ("AGS-50NX", manufactured by Shimadzu Corporation). Each was fixed to the chuck. After that, one set of the two sets of lead tape groups is placed on one side with respect to the plane of the sample piece 31, and the other set of the two sets of lead tape groups is placed on the basis of the plane of the sample piece 31. A 180 ° tensile test is performed to pull at a speed of 300 mm/min in opposite directions (up and down directions with respect to the plane of the sample piece 31) with respect to the plane of the sample piece 31 as a reference, so as to be multidirectional. The peak value (magnitude of force) appearing when the end portion including the attachment side 33 of the sample piece 31 was torn was measured. The measurement was performed under conditions of a temperature of 23°C and a relative humidity of 55%. This measurement was performed 5 times, and the average value of the magnitudes of the measured forces was taken as the tear strength.

[Tear test (sensory evaluation)]

Rectangular sample pieces were prepared in the procedure described in the measurement of the tear strength. Under conditions of a temperature of 23 ° C. and a relative humidity of 55%, when the sample piece is torn by hand in a direction perpendicular to the side from the side where the end of the surface treatment film (the end where the uncoated region is formed) is located in the side of the sample piece The ease of tearing was evaluated. The evaluation of the ease of tearing was evaluated as the ease of tearing when tearing the substrate layer (Reference Example 1) having a thickness of 13 μm in the above procedure as being difficult to tear (below “B”), and evaluated as follows based on this.

A: Harder to tear than B.

B: It is difficult to tear.

C: Easier to tear than B.

[Measurement of viscosity]

The viscosity of the acrylic resin composition was measured with a Brookfield viscometer (B-type viscometer, manufactured by Brookfield Corporation) at a temperature of 25°C.

[Cross hatch test]

100 (10 x 10) cross hatches of 1 mm square were engraved on the coated layer surface of the surface treatment film so that the coated layer penetrated. After sticking an adhesive tape (cellophane adhesive tape CT405AP-24, manufactured by Nichiban) with a width of 24 mm to this cross hatch, the adhesive tape was peeled in the direction of 45 degrees with respect to the cross hatch surface. After peeling off the adhesive tape, the number of cross hatches remaining on the substrate layer was counted. The crosshatch test was conducted under conditions of a temperature of 23°C and a relative humidity of 55%.

base layer
[μm] coating layer uncoated area distance
L [mm] tear strength
[N] tear test crosshatch test Breakage during conveyance Example 1 13 you 20.6 1.8 B 100 radish Example 2 13 you 15.5 1.8 B 100 radish Example 3 13 you 10.8 1.7 B 100 radish Example 4 13 you 8.2 2.4 B 100 radish Example 5 13 you 6.7 2.1 B 100 radish Example 6 13 you 5.5 1.7 B 100 radish Example 7 13 you 4.0 1.4 B 100 radish Example 8 13 you 3.0 1.0 B 100 radish Example 9 13 you 2.0 1.6 B 100 radish Example 10 13 you 1.0 1.3 B 100 radish Comparative Example 1 13 you 0.2 0.4 C 100 you Comparative Example 2 13 you 0.0 0.4 C 100 you Reference example 1 13 radish - 2.3 B - radish Reference example 2 23 you 0.0 5.5 A 100 radish Reference example 3 23 radish - 7.3 A - radish

1: Surface treatment film
10: first end
11: base layer
12: coating layer
15: side
21: uncoated area
22: pottery area
31: Sample
33: side (attached side)
35: lead tape.

Claims (9)

A substrate layer having a thickness of less than 20 μm;
A coating layer formed on the surface of the substrate layer;
The first end having a tear strength of 0.5 N or more at a temperature of 23° C. and a relative humidity of 55%
Surface treatment film having a. According to claim 1,
The first end portion includes an uncoated region in which the coating layer is not formed on the surface of the substrate layer,
A surface treatment film in which a distance from an end of the base layer in the uncoated region to an end of the coated layer is 0.6 mm or more. According to claim 1 or 2,
The surface treatment film in which the said 1st end part is formed along a pair of opposite sides in planar view of the said surface treatment film. According to any one of claims 1 to 3,
At a temperature of 23 ° C. and a relative humidity of 55%, by a cross hatch test performed by forming 100 cross hatches in the coating layer of the surface treatment film, 90 or more of the cross hatches remain on the base layer Surface treatment film. According to any one of claims 1 to 4,
The base layer is a surface treatment film of a cyclic olefin resin film. According to any one of claims 1 to 5,
The said coating layer is a surface treatment film which is a hardened|cured material layer of the composition containing ultraviolet curable resin. According to any one of claims 1 to 6,
The surface treatment film is a long body,
The first end portion is formed at both end portions of the surface treatment film in the width direction of the surface treatment film. A polarizing plate comprising the surface treatment film according to any one of claims 1 to 7 and a linearly polarizing layer. As a manufacturing method of the polarizing plate according to claim 8,
A step of preparing a laminate having the surface treatment film and a protection film laminated so as to be peelable on the substrate layer side of the surface treatment film;
A step of conveying the surface treatment film obtained by peeling the protective film from the laminate;
Step of laminating the surface treatment film obtained in the step of conveying and the linear polarizing layer
Method for producing a polarizing plate comprising a.