KR102642673B1 - Laminate - Google Patents

Abstract

The purpose of the present invention is to provide a laminate in which peeling defects of the peeling film do not occur when the peeling film begins to be peeled from the short side having the cutout in a cut-processed laminate.
A surface protection film is laminated on one side of the polarizing plate, and a release film is laminated on the other side of the polarizing plate. The polarizing plate is a laminate including a polarizer, and the laminate has a cutout in plan view. , A laminate in which the maximum value of the peeling force is 1.0 N or less when the peeling film is peeled from the short side having the cutout portion.

Description

Laminate {LAMINATE}

The present invention relates to laminates.

Polarizers are widely used in image display devices such as liquid crystal displays and organic electroluminescence (EL) displays, and especially in recent years, in various mobile devices such as smartphones. Conventionally, a polarizing plate is used that is formed by bonding a protective film to one or both sides of a polarizer in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film.

Polarizing plates are generally marketed as a laminate in which a peelable surface protection film (also called a protection film) and a release film (also called a separate film) are adhered to the surface to prevent the surface from becoming dirty or damaged. .

When bonding a polarizing plate to a display element such as a liquid crystal cell or organic EL element, the release film bonded to the surface is peeled off, and the polarizing plate is bonded to the display device through the exposed adhesive layer. When peeling off the release film, the surface protection film side of the laminate (a film in which a surface protection film is laminated on one side of a polarizing plate and a release film is laminated on the other side) is held by a method such as suction or adsorption. It is fixed to a stand, and a release tape is bonded onto the release film. Thereafter, the release tape is pulled to remove the release film from the polarizer surface.

To suit the design of the image display device, the laminate is often processed into a shape other than a rectangular shape. Specifically, the laminate is perforated in the plane, the corners are R-processed in a plan view, or the laminate is cut in a plan view. In particular, in the case where the laminate is cut in plan view, when the peeling film is started to be peeled from the short side having the cutout, the peeling film cannot be peeled when the peeling tip reaches the cutout. There was a problem. Following the movement of the release film, the fixed polarizing plate and surface protection film rise from the holding table, the fixation of the polarizing plate and surface protection film is released, and the release film cannot be easily peeled.

This problem can be solved by increasing the forces such as the suction force or adsorption force when fixing the laminated body, or by reducing the adhesive force of the release film, but a new problem arises. In other words, if the force acting on the laminate, such as the suction force or adsorption force, increases, traces remain on the polarizing plate and the appearance deteriorates. Additionally, if the adhesive force of the release film is reduced, a gap will be created between the release film and the polarizing plate when an impact is applied to the layered product during transportation or the like.

[Patent Document 1] WO2018/016285A1

An object of the present invention is to provide a laminate in which peeling film defects do not occur.

[1] A surface protective film is laminated on one side of the polarizer,

A release film is laminated on the other side of the polarizer,

The polarizing plate is a laminate including a polarizer,

The laminate has a notch in plan view,

A laminate whose maximum value of peeling force is 1.0 N or less when the peeling film is peeled from the short side having the cutout.

[2] The laminate according to [1], wherein the shape of the cutout satisfies the following equation (1).

r>3d-14 (1)

[In equation (1), d (mm) represents the depth of the notch, and r (mm) represents the radius of curvature of the inner corner of the notch.]

[3] The polarizing plate has an adhesive layer on the surface of the release film side,

The laminate according to [1] or [2], wherein the adhesive force between the release film and the adhesive layer is 0.02 N/25 mm or more and 0.10 N/25 mm or less.

[4] A sticking step of attaching a tape to one corner of a short side having a notch in the laminate according to any one of [1] to [3];

A peeling step is provided to raise the tape and peel the release film from the laminate,

In the peeling process, the angle formed between the peeling direction of the tape and the short side orthogonal to the short side having the cutout is 25° or more and 65° or less.

According to the present invention, it is possible to provide a laminate in which peeling defects of the peeling film do not occur.

1 is a schematic cross-sectional view showing an example of the layer structure of the laminate of the present invention.
Figure 2 is a schematic cross-sectional view showing an example of the layer structure of the laminate of the present invention.
Figure 3 is a schematic top view showing an example of a cutout portion of the laminate of the present invention.
Figure 4 is a schematic top view showing an example of a cutout portion of the laminate of the present invention.
Figure 5 is a schematic top view showing an example of a method of peeling a release film from a laminate.

<Laminate>

In the laminate, a surface protection film is laminated on one side of the polarizing plate, and a release film is laminated on the other side of the polarizing plate. A polarizing plate has at least a polarizer. Hereinafter, an example of the layer structure of the laminate of the present invention will be described with reference to the drawings. In addition to the polarizer, the polarizing plate may be provided with a protective film, a retardation film, a brightness improving film, an adhesive layer, etc.

1 is a schematic cross-sectional view showing an example of a laminate of the present invention. The laminate 100 shown in FIG. 1(a) includes a polarizing plate 10, a surface protection film 30 laminated on one side of the polarizing plate 10, and a surface protection film 30 laminated on the other side of the polarizing plate 10. It consists of a peeled film (20). In the polarizer 10, a protective film 12 is laminated on one side of the polarizer 11 through an adhesive layer (not shown), and a retardation film 14 is laminated on the other side through an adhesive layer 16. , It is a layer structure in which the adhesive layer 15 is laminated on the retardation film 14.

The laminate 101 shown in FIG. 1(b) includes a polarizing plate 10, a surface protection film 30 laminated on one side of the polarizing plate 10, and a surface protection film 30 laminated on the other side of the polarizing plate 10. It consists of a peeled film (20). The polarizing plate 10 has a protective film 12 laminated on one side of the polarizer 11 through an adhesive layer not shown, and a protective film 13 through an adhesive layer not shown on the other side. It has a layer structure in which the retardation film 14 is laminated on the protective film 13 through the adhesive layer 16, and the adhesive layer 15 is laminated on the retardation film 14.

The laminate 102 shown in FIG. 2(a) includes a polarizing plate 10, a surface protection film 30 laminated on one side of the polarizing plate 10, and a surface protection film 30 laminated on the other side of the polarizing plate 10. It consists of a peeled film (20). The polarizing plate 10 has a protective film 13 laminated on one side of the polarizer 11 through an adhesive layer (not shown), and a luminance enhancement film 17 through an adhesive layer 16 on the other side. It has a layer structure in which the adhesive layer 15 is laminated on the protective film 13.

The laminate 103 shown in FIG. 2(b) includes a polarizing plate 10, a surface protection film 30 laminated on one side of the polarizing plate 10, and a surface protection film 30 laminated on the other side of the polarizing plate 10. It consists of a peeled film (20). The polarizing plate 10 has a protective film 12 laminated on one side of the polarizer 11 through an adhesive layer not shown, and a protective film 13 through an adhesive layer not shown on the other side. It has a layer structure in which the brightness enhancing film 17 is laminated on the protective film 12 through the adhesive layer 16, and the adhesive layer 15 is laminated on the protective film 13.

In the laminates 100 to 103, it is preferable that the surface protection film 30 and the release film 20 are each members that constitute the outermost surface of the laminate. The laminates 100 to 103, the polarizing plate 10, the release film 20, and the surface protection film 30 may have layers other than those shown.

The laminate preferably has a substantially rectangular shape on its main surface. The main surface refers to the surface with the largest area corresponding to the display surface. A substantially rectangular shape means that the laminate is a shape in which at least one of the four corners (corners) of the main surface is cut or rounded to form an obtuse angle, or a part of the end surface perpendicular to the main surface is angled in the in-plane direction. It may have a recessed concave portion (notch) or a portion of the main surface may have a perforated portion cut out in a shape such as a circle, an oval, a polygon, or a combination thereof.

The laminate has a notch on at least one end face when viewed in plan. As mentioned above, the notch refers to a portion in which a portion of the end surface perpendicular to the main surface is depressed in the in-plane direction when viewed from the top. The laminate may have one or more notches. The laminate may have a plurality of cutouts on one short side, but it is preferable to have one cutout on one short side. The cutout may be formed on a short side perpendicular or parallel to the absorption axis of the polarizer. Since the laminated body has a notch on the end surface when viewed from the top, when the laminated body is viewed from the top, the end has a shape that is recessed toward the inside of the surface.

In the laminate of the present invention, when the peeling film is peeled from the short side having the notch, the maximum peeling force is 1.0 N or less. The maximum value of peeling force is preferably 0.8 N or less. The maximum value of peeling force may be 0.1 N or more. The maximum value of the peeling force is controlled by the shape of the notch, etc., as will be described later. The maximum value of peeling force can be measured by the method described in the Examples described later. By using such a peeling force, peeling defects are unlikely to occur.

It is preferable that the shape of the notch provided in the laminate of the present invention satisfies the following formula (1).

When a laminate has a plurality of notches, at least one notch may satisfy equation (1), and all notches may satisfy equation (1). When the shape of the notch satisfies the above equation (1), the force required when peeling the release film can be reduced.

r>3d-14 (1)

[In equation (1), d (mm) represents the depth of the notch, and r (mm) represents the radius of curvature of the inner corner of the notch.]

Figure 3 shows a schematic diagram of an example of the laminate 104 of the present invention as seen from the top. This laminate 104 has a notch 40 when viewed from the top. The notch 40 has a concave shape from the end toward the inside of the surface. The depth of the notch corresponds to the length of both arrows d in FIG. 3 and refers to the distance from the short side to the deepest part of the concave portion. The radius of curvature of the inner corner of the cutout corresponds to the radius of curvature of the corner shown by one arrow R in FIG. 3 . When the curvature radii of the two inner corners are different, r represents the smaller radius of curvature. The curvature radii of the two inner corners are preferably the same.

r and d are both values greater than 0. Although not particularly limited, the upper limit of r may be 17 mm. Although not particularly limited, the upper limit of d may be 20 mm. d may be 10 mm or less, and may be 7 mm or less.

When d is 2 mm or more and 5 mm or less, r is preferably 2 mm or more. When d is greater than 5 mm and less than or equal to 6 mm, r is preferably greater than or equal to 8 mm. When d is greater than 6 mm and less than 8 mm, r is preferably greater than or equal to 13 mm. When d is 8 mm or more, r is preferably 17 mm or more.

The width of the notch can be 5 mm or more and 50 mm or less, and is preferably 5 mm or more and 20 mm or less. The width of the notch is the length parallel to the short side and refers to the longest distance of the notch.

The shape of the cutout may be specifically the shape shown in FIG. 4. Figure 4 is a schematic diagram showing an example of the cutout portion 40 in the laminate of the present invention in plan view, and the cutout portion 40 is as shown in Figure 4(a) when viewed from the top. Similarly, a shape in which rounding is formed on two inner corners of a rectangular concave portion, and a rounding is formed on four corners of the rectangular concave portion as shown in FIG. 4(b). It can be one shape. Additionally, the notch may have a shape in which rounding is formed at the corner of the trapezoid-shaped concave portion, as shown in FIG. 4(c). As shown in FIGS. 4(a) to 4(c), the cutout may have a straight portion at the bottom, and as shown in FIG. 4(d), the cutout may have a straight portion at the bottom. It's okay if you don't have it.

The laminate may be obtained by manufacturing a long laminate using roll-to-roll while transporting each member constituting the laminate, and cutting this, or preparing each member of a predetermined shape, It may be obtained by sequential stacking.

When the laminate has a rectangular shape (or substantially rectangular shape) with a long side and a short side, the length of the long side is preferably 35 to 5 cm, more preferably 25 to 10 cm, and the length of the short side is 25 to 5 cm. It is preferable that it is 5 cm, and it is more preferable that it is 20 to 6 cm. By setting the size in this range, peelability can be further improved.

Hereinafter, each member included in the laminate will be explained.

<Polarizer>

The polarizing plate 10 is a polarizing element that includes at least a polarizer, and usually further includes a thermoplastic resin film bonded to one or both sides. The thermoplastic resin film may be a protective film that protects a polarizer, another film with an optical function, etc. The thermoplastic resin film may be provided with a resin layer (e.g., at least one type of optical layer selected from hard coat layer, antistatic layer, anti-glare layer, light diffusion layer, anti-reflection layer, low refractive index layer, anti-pollution layer, etc.) laminated on its surface. A thermoplastic resin film can be bonded to a polarizer through an adhesive layer. The surface protection film 30 may be laminated on the surface of this resin layer.

When the laminate further includes a brightness enhancing film or a retardation film, the effect of the present invention is remarkable. A polarizing plate containing a brightness improving film or the like has low rigidity and is prone to peeling defects. According to the present invention, even when the laminate includes a brightness improving film or the like, the occurrence of peeling defects can be reduced.

The thickness (μm) of the polarizing plate is usually 150 μm or less, and in the case of low rigidity of 75 μm or less, and even 70 μm or less, the effect of the present invention is remarkable. The thickness of the polarizing plate 10 is preferably 30 μm or more, and more preferably 50 μm or more.

(1) Polarizer

The polarizer constituting the polarizer 10 is an absorption type that has the property of absorbing linearly polarized light having a vibration plane parallel to its absorption axis and transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis (parallel to the transmission axis). It is a polarizer, and a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film can be suitably used. The polarizer includes, for example, a step of uniaxially stretching a polyvinyl alcohol-based resin film; A process of adsorbing a dichroic dye by dyeing a polyvinyl alcohol-based resin film with a dichroic dye; A process of treating a polyvinyl alcohol-based resin film to which a dichroic dye is adsorbed with a crosslinking solution such as an aqueous boric acid solution; and a step of washing with water after treatment with a crosslinking solution.

As the polyvinyl alcohol-based resin, saponified polyvinyl acetate-based resin can be used. Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of other monomers that can be copolymerized with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

In this specification, “(meth)acrylic” means at least one selected from acrylic and methacryl. The same applies to “(meth)acryloyl”, “(meth)acrylate”, etc.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, and is preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, and is preferably 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined based on JIS K 6726.

A film formed of such a polyvinyl alcohol-based resin is used as a raw film of a polarizer. The method of forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is adopted. The thickness of the polyvinyl alcohol-based raw film is not particularly limited, but in order to keep the thickness of the polarizer to 15 μm or less, it is preferable to use a film of 5 to 35 μm. More preferably, it is 20 μm or less.

Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before or during crosslinking treatment. Additionally, uniaxial stretching may be performed in these plural stages.

During uniaxial stretching, the material may be stretched uniaxially between rolls with different peripheral speeds, or it may be stretched uniaxially using hot rolls. In addition, uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which stretching is performed in a state in which the polyvinyl alcohol-based resin film is swollen using a solvent or water. The stretching ratio is usually 3 to 8 times.

As a method of dyeing a polyvinyl alcohol-based resin film with a dichroic dye, for example, a method of immersing the film in an aqueous solution containing a dichroic dye is adopted. As a dichroic dye, iodine or a dichroic organic dye is used. On the other hand, it is preferable to immerse the polyvinyl alcohol-based resin film in water before dyeing treatment.

As a crosslinking treatment after dyeing with a dichroic dye, a method of immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid is usually adopted. When using iodine as a dichroic dye, it is preferable that this aqueous solution containing boric acid contains potassium iodide.

The thickness of the polarizer is usually 30 μm or less, preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. In particular, setting the thickness of the polarizer to 15 μm or less is advantageous for thinning the laminate. The thickness of the polarizer is usually 2 μm or more, and from the viewpoint of providing elasticity to the polarizing plate, it is preferably 3 μm or more.

As a polarizer, for example, as described in Japanese Patent Application Laid-Open No. 2016-170368, you may use a cured film in which a liquid crystal compound is polymerized and a dichroic dye is oriented. As the dichroic dye, one having absorption within the wavelength range of 380 to 800 nm can be used, and it is preferable to use an organic dye. As a dichroic dye, an azo compound can be mentioned, for example. A liquid crystal compound is a liquid crystal compound that can be polymerized while being aligned, and may have a polymerizable group in the molecule.

(2) Protective film

The protective film that can be laminated on one or both sides of the polarizer is a thermoplastic resin with light transparency (preferably optically transparent), such as chain polyolefin resin (polypropylene resin, etc.), cyclic resin. ) Polyolefin-based resins such as polyolefin-based resins (norbornene-based resins, etc.); Cellulose-based resins such as triacetylcellulose and diacetylcellulose; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resins such as methyl methacrylate resins; polystyrene-based resin; polyvinyl chloride-based resin; Acrylonitrile, butadiene, and styrene-based resin; Acrylonitrile/styrene resin; polyvinyl acetate-based resin; polyvinylidene chloride-based resin; polyamide-based resin; polyacetal resin; Modified polyphenylene ether-based resin; polysulfone-based resin; polyethersulfone-based resin; polyarylate-based resin; polyamideimide-based resin; It may be a film made of polyimide resin or the like.

Examples of the linear polyolefin-based resin include polyethylene resin (polyethylene resin, which is a homopolymer of ethylene, or copolymer mainly based on ethylene), polypropylene resin (polypropylene resin, which is a homopolymer of propylene, or copolymer mainly based on propylene), and In addition to homopolymers of the same chain olefin, copolymers composed of two or more types of chain olefins can be mentioned.

Cyclic polyolefin-based resin is a general term for resins polymerized using cyclic olefins as polymerization units, for example, Japanese Patent Application Laid-Open No. 1-240517, Japanese Patent Application Publication No. 3-14882, and Japanese Patent Application Publication No. 3 -Resins described in Publication No. 122137, etc. may be mentioned. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, and copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically random copolymers). ), and graft polymers modified with unsaturated carboxylic acids or their derivatives, and hydrides thereof. Among them, norbornene-based resins using norbornene-based monomers such as norbornene or polycyclic norbornene-based monomers as cyclic olefins are preferably used.

Polyester-based resins are resins having an ester bond, excluding the cellulose ester-based resins below, and are generally composed of polycondensates of polyhydric carboxylic acids or their derivatives and polyhydric alcohols. As the polyhydric carboxylic acid or its derivative, a divalent dicarboxylic acid or a derivative thereof can be used, and examples include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalene dicarboxylic acid. As the polyhydric alcohol, a diol can be used, and examples include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. Representative examples of polyester resins include polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

(meth)acrylic resin is a resin whose main constituent monomer is a compound having a (meth)acryloyl group. Specific examples of (meth)acrylic resin include poly(meth)acrylic acid esters such as polymethyl methacrylate; Methyl methacrylate-(meth)acrylic acid copolymer; Methyl methacrylate-(meth)acrylic acid ester copolymer; Methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; (meth)acrylate methyl-styrene copolymer (MS resin, etc.); It includes copolymers of methyl methacrylate and compounds having an alicyclic hydrocarbon group (e.g., methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer containing poly(meth)acrylic acid C _1-6 alkyl ester, such as methyl poly(meth)acrylate, as the main component is used, and more preferably, a polymer containing methyl methacrylate as the main component (50 to 100% by weight, Preferably 70 to 100% by weight of methyl methacrylate-based resin is used.

Cellulose ester-based resin is an ester of cellulose and fatty acids. Specific examples of cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Additionally, copolymers thereof and those in which part of the hydroxyl group has been modified with another substituent can also be mentioned. Among these, cellulose triacetate (triacetylcellulose) is particularly preferable.

Polycarbonate-based resin is an engineering plastic made of a polymer in which monomer units are bonded through carbonate groups.

It is also useful to control the retardation value of the protective film to a value suitable for image display devices such as liquid crystal displays. For example, in an in-plane switching (IPS) mode liquid crystal display device, it is desirable to use a film with a retardation value of substantially zero as a protective film. Substantially zero phase difference value means that the in-plane phase difference value R ₀ at a wavelength of 590 nm is 10 nm or less, the absolute value of the thickness direction retardation value R _th at a wavelength of 590 nm is 10 nm or less, and the wavelength is 480 to 750 nm. It means that the absolute value of the thickness direction retardation value R _th in nm is 15 nm or less.

For example, depending on the mode of the liquid crystal display device, the protective film may be subjected to stretching and/or shrinking processing to provide an appropriate retardation value. For example, for the purpose of viewing angle compensation, a retardation layer (or film) with a single-layer or multi-layer structure can be used as a protective film. In this case, the polarizer 10 may be an elliptically polarizer or circular polarizer including a stacked structure of a polarizer and a retardation layer, or a polarizer with a viewing angle compensation function including a retardation layer.

The thickness of the protective film is usually 1 to 100 μm, but from the viewpoint of strength, handleability, etc., it is preferably 5 to 60 μm, more preferably 10 to 55 μm, and even more preferably 15 to 40 μm.

When a protective film is bonded to both surfaces of a polarizer, these protective films may be comprised of the same type of thermoplastic resin, or may be comprised of a different type of thermoplastic resin. Additionally, the thickness may be the same or different. Moreover, they may have the same phase difference characteristics or may have different phase difference characteristics.

As described above, at least one side of the protective film has a surface such as a hard coat layer, an anti-glare layer, a light diffusion layer, an anti-reflection layer, a low refractive index layer, an anti-static layer, and an anti-pollution layer on its outer surface (the surface opposite to the polarizer). It may be provided with a treatment layer (coating layer). Meanwhile, the thickness of the protective film includes the thickness of the surface treatment layer.

From the viewpoint of suppressing the mixing of air bubbles between the surface protection film and the polarizing plate, the surface on the surface protection film 30 side of the polarizing plate 10 (the surface to which the surface protection film 30 is bonded, even if it is a surface treatment layer) It is preferable that the arithmetic mean roughness Ra based on JIS B 0601:2013 is small. Specifically, Ra of the surface is preferably 0.3 μm or less, more preferably 0.2 μm or less, and still more preferably 0.15 μm or less. Ra of the surface is usually 0.001 μm or more, for example, 0.005 μm or more.

The protective film can be bonded to the polarizer, for example, through an adhesive layer. As the adhesive forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and water-based adhesives and active energy ray-curable adhesives are preferred.

Examples of water-based adhesives include adhesives made of polyvinyl alcohol-based resin aqueous solutions, water-based two-component urethane-based emulsion adhesives, and the like. Among them, a water-based adhesive consisting of an aqueous solution of polyvinyl alcohol-based resin is suitably used. Polyvinyl alcohol-based resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and polyvinyl alcohol-based copolymers obtained by saponifying copolymers of vinyl acetate and other monomers copolymerizable with it. A polymer or a modified polyvinyl alcohol-based polymer whose hydroxyl groups are partially modified can be used. The water-based adhesive may contain a crosslinking agent such as an aldehyde compound (glyoxal, etc.), an epoxy compound, a melamine-based compound, a methylol compound, an isocyanate compound, an amine compound, and a polyvalent metal salt.

When using a water-based adhesive, it is preferable to perform a drying process to remove water contained in the water-based adhesive after bonding the polarizer and the protective film. After the drying process, a curing process may be provided, for example, at a temperature of 20 to 45°C.

The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet ray-curable adhesive.

The curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Cationic polymerizable curable compounds include, for example, epoxy-based compounds (compounds having one or two or more epoxy groups in the molecule), oxetane-based compounds (compounds having one or two or more oxetane rings in the molecule), or these. A combination of . Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or two or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, or A combination of these can be mentioned. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used together. Active energy ray-curable adhesives usually further include a cationic polymerization initiator and/or a radical polymerization initiator for initiating a curing reaction of the curable compound.

When bonding a polarizer and a protective film, surface activation treatment may be performed on at least one of these bonding surfaces in order to increase adhesiveness. Surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing active line treatment (ultraviolet treatment, electron beam treatment, etc.); Wet treatments such as ultrasonic treatment, saponification treatment, and anchor coat treatment using solvents such as water or acetone can be used. These surface activation treatments may be performed individually, or two or more may be combined.

When protective films are bonded to both sides of a polarizer, the adhesive for bonding these protective films may be the same type of adhesive or may be a different type of adhesive.

(3) Other films

The polarizing plate 10 may include films other than the polarizer and the protective film, and representative examples thereof are a brightness enhancement film and a retardation film. When the polarizing plate 10 includes another film, the surface protection film 30 may be laminated on the surface of this film or on the surface of a surface treatment layer laminated on this film.

The brightness enhancing film is also called a reflective polarizer, and a polarization conversion element that has the same function as separating light emitted from a light source (backlight) into transmission polarization, reflection polarization, or scattering polarization is used. By disposing the brightness improvement film on the polarizer, the emission efficiency of linearly polarized light emitted from the polarizer can be improved by using retroactive light, which is reflected polarization or scattered polarization. The brightness improving film can be laminated on the polarizer through an adhesive layer. Another film, such as a protective film, may be interposed between the polarizer and the brightness improving film.

The brightness enhancing film may be, for example, an anisotropic reflective polarizer. An example of an anisotropic reflective polarizer is an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction, and a specific example is “APF” manufactured by 3M. Another example of an anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ/4 plate, and a specific example thereof is “PCF” manufactured by Nitto Denko Co., Ltd. Another example of an anisotropic reflective polarizer is a reflective grid polarizer, a specific example of which is a metal grid reflective polarizer that emits reflected polarized light even in the visible light region by subjecting metal to fine processing, and a metal grid polarizer made by adding metal particles to a polymer matrix and stretching it. It's a film.

As described above, on the outer surface of the brightness enhancement film, there is a hard coat layer, an anti-glare layer, a light diffusion layer, a phase difference layer (a phase difference layer with a phase difference value of 1/4 wavelength, etc.), an anti-reflection layer, a low refractive index layer, an anti-static layer, and contamination. You may form a surface treatment layer (coating layer) similar to an prevention layer. By forming such a layer, adhesion to the backlight tape and uniformity of the displayed image can be improved. The thickness of the brightness improving film 50 is usually 10 to 100 μm, but is preferably 10 to 50 μm, and more preferably 10 to 30 μm.

Examples of the retardation film include positive A plates such as quarter-wave (λ/4) plates and half-wave (λ/2) plates, and positive C plates. The λ/4 plate is a layer whose in-plane retardation value Re(550) at a wavelength of 550 nm satisfies the relationship of 100 nm≤Re(550)≤200 nm. The λ/4 plate may exhibit reverse wavelength dispersion satisfying Re(450)<Re(550)<Re(650). The λ/2 plate is a layer in which Re(550) satisfies 210 nm≤Re(550)≤300 nm. The positive C plate satisfies the relationship Nz>Nx≥Ny, and the phase difference value Rth(λ) in the thickness direction at the wavelength λ nm satisfies the relationship of -300 nm≤Rth(550)≤-20 nm. It is desirable to do so.

The retardation film can be formed, for example, from the resins exemplified as materials for the protective film, and among them, cyclic olefin resins and styrene resins are preferable. The phase contrast layer may be formed as a single layer or may be formed as a plurality of layers. The retardation layer having a plurality of layers includes, for example, a resin film (base film) exemplified as the material of the above protective film, and a layer in which a liquid crystal compound polymerized with a liquid crystal compound is cured, and a plurality of layers (e.g., two layers). It may include a layer in which the liquid crystal compound is hardened. The layer having a phase difference may be a layer in which a resin film and/or a liquid crystal compound is cured. The resin film can also serve as the protective film.

The retardation film may be composed of one type of retardation layer, or may be composed of multiple types of retardation layers. When the retardation film consists of a plurality of retardation layers, a combination of a 1/4 wave plate and a 1/2 wave plate, or a combination of a 1/4 wave plate and a positive C plate is preferable.

The retardation film preferably includes a layer in which the liquid crystal compound is hardened, and when the retardation film consists of a plurality of retardation layers, either retardation layer may include a layer in which the liquid crystal compound is hardened. There is no particular limitation on the type of liquid crystal compound, but based on its shape, it can be classified into rod-like type (rod-shaped liquid crystal compound) and disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound). You can. Additionally, there are low-molecular type and high-molecular type, respectively. On the other hand, a polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics and Phase Transition Dynamics, written by Masao Doi, 2 pages, Iwanami Shoten, 1992). In this embodiment, either liquid crystal compound can be used. Additionally, two or more types of rod-shaped liquid crystal compounds, two or more types of disc-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disc-shaped liquid crystal compound may be used.

Meanwhile, as the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Application Publication No. Heisei 11-513019 or paragraphs [0026] to [0098] of Japanese Patent Application Publication No. 2005-289980 can be suitably used. there is. Disk-shaped liquid crystal compounds include, for example, those described in paragraphs [0020] to [0067] of Japanese Patent Application Laid-Open No. 2007-108732, or paragraphs [0013] to [0108] of Japanese Patent Application Laid-Open No. 2010-244038. It can be used appropriately.

It is more preferable to form the retardation layer using a liquid crystal compound (rod-shaped liquid crystal compound or disc-shaped liquid crystal compound) having a polymerizable group. As a result, temperature and humidity changes in optical characteristics can be reduced.

The liquid crystal compound may be a mixture of two or more types. In that case, it is preferable that at least one has two or more polymerizable groups. That is, the retardation layer is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disc-shaped liquid crystal compound having a polymerizable group by polymerization. In this case, after becoming a layer, it is no longer necessary to exhibit liquid crystallinity.

The type of polymerizable group contained in the rod-shaped liquid crystal compound or disk-shaped liquid crystal compound is not particularly limited, and for example, a functional group capable of addition polymerization reaction, such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group, is preferable. More specifically, examples include (meth)acryloyl group, vinyl group, styryl group, and allyl group. Among them, (meth)acryloyl group is preferable. On the other hand, (meth)acryloyl group is a concept that includes both methacryloyl group and acryloyl group.

The method of forming the phase contrast layer is not particularly limited and includes known methods. For example, a composition for forming an optically anisotropic layer (hereinafter simply referred to as “composition”) containing a liquid crystal compound having a polymerizable group is applied to a predetermined substrate (including a temporary substrate) to form a coating film. A retardation layer can be manufactured by performing a curing treatment (irradiation of ultraviolet rays (light irradiation treatment) or heat treatment) on the obtained coating film. The manufactured retardation layer can be transferred onto, for example, a polarizer or a protective film.

The composition can be applied by known methods such as wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating.

The composition may contain components other than the liquid crystal compound described above. For example, the composition may contain a polymerization initiator. The polymerization initiator used is selected depending on the type of polymerization reaction, for example, a thermal polymerization initiator or a photopolymerization initiator. For example, photopolymerization initiators include α-carbonyl compounds, acyloin ethers, α-hydrocarbon substituted aromatic acyloin compounds, polynuclear quinone compounds, combinations of triarylimidazole dimers and p-aminophenyl ketones, etc. . The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition.

Additionally, the composition may contain a polymerizable monomer from the viewpoint of uniformity and strength of the coating film. Examples of polymerizable monomers include radically polymerizable or cationically polymerizable compounds. Among them, multifunctional radically polymerizable monomers are preferable.

On the other hand, the polymerizable monomer is preferably one that is copolymerizable with the liquid crystal compound containing the polymerizable group described above. Specific examples of polymerizable monomers include those described in paragraphs [0018] to [0020] of Japanese Patent Application Laid-Open No. 2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the liquid crystal compound.

Additionally, the composition may contain a surfactant from the viewpoint of uniformity and strength of the coating film. As surfactants, conventionally known compounds can be mentioned. Among these, fluorine-based compounds are particularly preferable.

Additionally, the composition may contain a solvent, and an organic solvent is preferably used. Organic solvents include, for example, amides (e.g. N,N-dimethylformamide), sulfoxides (e.g. dimethyl sulfoxide), heterocyclic compounds (e.g. pyridine), hydrocarbons (e.g. benzene, hexane), alkyl halides (e.g. e.g. chloroform, dichloromethane), esters (e.g. methyl acetate, ethyl acetate, butyl acetate), ketones (e.g. acetone, methyl ethyl ketone), ethers (e.g. tetrahydrofuran, 1,2-dimethoxyethane) I can hear it. Among them, alkyl halides and ketones are preferable. Additionally, two or more types of organic solvents may be used together.

In addition, the composition contains various alignment agents such as vertical alignment accelerators such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and horizontal alignment accelerators such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. It's okay to have it. Additionally, the composition may contain an adhesion improver, a plasticizer, a polymer, etc. in addition to the above components.

The retardation film may contain an alignment film that has the function of defining the orientation direction of the liquid crystal compound. The alignment film generally contains polymer as its main component. As polymer materials for alignment films, there are descriptions in many literature, and many commercial products are available. Among these, as the polymer material, it is preferable to use polyvinyl alcohol, polyimide, and derivatives thereof, and it is especially preferable to use modified or unmodified polyvinyl alcohol.

Meanwhile, a known alignment treatment is usually performed on the alignment film. Examples include rubbing treatment and photo-alignment treatment by irradiating polarized light, but from the viewpoint of the surface roughness of the alignment film, photo-alignment treatment is preferable.

The thickness of the layer in which the liquid crystal compound is cured is not particularly limited, but is preferably 0.5 to 10 μm, and more preferably 1.0 to 5 μm. The thickness of the alignment film is not particularly limited, but is often 20 μm or less, and among these, it is preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.01 to 1 μm.

(4) Adhesive layer

The polarizing plate 10 preferably has an adhesive layer 15 on its outermost surface. This pressure-sensitive adhesive layer can be used to bond the polarizing plate 10 to a display element (e.g., a liquid crystal cell, an organic EL element) or another optical member, and is exposed by peeling the release film 20. Additionally, the adhesive layer can also be used to laminate a polarizer, a protective film, a brightness enhancing film, and a retardation film. 1 and 2, the adhesive layer 16 corresponds to this. The adhesive layer can be composed of an adhesive composition containing as a main component a resin such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether. Among them, an adhesive composition containing a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is suitable. The adhesive composition may be of an active energy ray curing type or a thermosetting type.

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include (meth)acrylate, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. A polymer or copolymer containing one or two or more types of acrylic acid ester as a monomer is suitably used. It is preferable to copolymerize a polar monomer with the base polymer. Polar monomers include, for example, (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycyrrhizate. Monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as dil (meth)acrylate, can be mentioned.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include those that are divalent or higher metal ions and form a carboxylic acid metal salt between carboxyl groups; It is a polyamine compound and forms an amide bond between carboxyl groups; A polyepoxy compound or polyol that forms an ester bond between carboxyl groups; It is a polyisocyanate compound, and an example is one that forms an amide bond between carboxyl groups. Among them, polyisocyanate compounds are preferable.

An active energy ray-curable adhesive composition has the property of curing when irradiated with active energy rays such as ultraviolet rays or electron beams, has adhesiveness even before irradiation of active energy rays, and can be adhered to an adherend such as a film, and can be irradiated with active energy rays. It is an adhesive composition that has properties that allow adjustment of adhesion by curing. The active energy ray-curable adhesive composition is preferably of an ultraviolet ray-curable type. The active energy ray curable adhesive composition further contains an active energy ray polymerizable compound in addition to the base polymer and crosslinking agent. Additionally, if necessary, a photopolymerization initiator, a photosensitizer, etc. may be contained.

The adhesive composition contains fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, antistatic agents, tackifiers, fillers (metal powders or other inorganic powders, etc.), and oxidation. It may contain additives such as inhibitors, ultraviolet absorbers, dyes, pigments, colorants, defoaming agents, corrosion inhibitors, and photopolymerization initiators.

The pressure-sensitive adhesive layer can be formed by applying an organic solvent dilution of the pressure-sensitive adhesive composition onto a substrate and drying it. The substrate may be a polarizer, a protective film, another optical film such as a brightness enhancement film, a release film (e.g., release film 20), etc. When an active energy ray-curable adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating active energy rays to the formed adhesive layer.

The thickness of the adhesive layer 15 is usually 1 to 40 μm, but from the viewpoint of thinning the laminate and suppressing dimensional changes in the polarizing plate 10 while maintaining good processability, it is 3 to 25 μm (e.g., 3 to 25 μm). It is preferable to set it to 20 ㎛, further 3 to 15 ㎛. The thickness of the adhesive layer 16 is usually 1 to 20 μm, but is preferably 3 to 10 μm.

The adhesive layer 15 on which the release film 20 is laminated has an adhesive force to the release film of 0.10 N/25 mm or less, and preferably 0.04 N/25 mm or less. By setting this adhesion, the polarizing plate does not float when peeling the release film, and the peelability is further improved. Additionally, the adhesion force is 0.02 N/25 mm or more. By achieving such adhesion, it is easy to prevent a gap from occurring between the release film and the adhesive layer even if an impact is applied to the laminated body during transportation or the like. In this specification, the adhesion of the adhesive layer to the release film is a value measured by the method described in the Examples described later.

<Surface protection film>

The surface protection film 30 may include a base film 31 and an adhesive layer 32 laminated thereon. The surface protection film 30 is a film for protecting the surface of the polarizing plate 10, and is usually peeled and removed together with the adhesive layer it has after the laminate is bonded to, for example, a display element or another optical member.

The surface protection film is generally more elastic than the brightness improving film and is important for improving the peelability of the release film. In this specification, the thickness of the surface protection film is the sum of the thickness of the base film and the thickness of the adhesive layer laminated thereon, and is preferably 30 μm or more, and more preferably 50 μm or more. On the other hand, if the thickness of the surface protection film is too large, peeling is likely to occur between the surface protection film and the polarizing plate when peeling the release film, so the thickness of the surface protection film is preferably 100 μm or less, and is more preferable. Typically, it is 70 ㎛ or less.

The base film is preferably a thermoplastic resin film. Thermoplastic resins constituting the thermoplastic resin film include, for example, polyolefin resins such as polyethylene resins and polypropylene resins; Cyclic polyolefin resin; Polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate-based resin; (meth)acrylic resin, etc. can be mentioned. The base film may have a single-layer structure or a multi-layer structure.

The thickness of the base film may be 20 to 150 ㎛ (eg, 30 to 80 ㎛, preferably 30 to 60 ㎛). Regarding the composition of the adhesive layer, the technology regarding the adhesive layer of the above-described polarizing plate is basically cited.

In particular, the storage elastic modulus of the adhesive layer is preferably 0.15 MPa or less, more preferably 0.14 MPa or less, and still more preferably 0.10 MPa or less at 80°C. Usually, the storage modulus of the adhesive layer at 80°C is 0.01 MPa or more. In this specification, the storage elastic modulus of the adhesive layer can be measured using a commercially available viscoelasticity measuring device, for example, the viscoelasticity measuring device “DYNAMIC ANALYZER RDA II” manufactured by REOMETRIC.

The surface protection film 30 may contain an antistatic agent. The antistatic agent can be contained in the adhesive layer, for example. Instead of containing an antistatic agent in the adhesive layer, or together with it, an antistatic layer containing an antistatic agent may be formed on the surface of the base film opposite to the surface on which the adhesive layer is laminated.

Examples of antistatic agents include ionic compounds. An ionic compound is a compound having an inorganic cation or organic cation and an inorganic anion or organic anion. Two or more types of ionic compounds may be used.

<Release film>

The release film 20 is a film temporarily bonded to protect the surface of the adhesive layer until it is bonded to a display element (eg, liquid crystal cell, organic EL element) or other optical member. It is possible to adjust the adhesion of the release film 20 to the adhesive layer 15 by subjecting one side to a release treatment with a mold release agent such as silicone or fluorine. The release film 20 is composed of a thermoplastic resin film that has undergone release treatment, and an adhesive layer can be bonded to the release treatment surface.

The thermoplastic resin constituting the release film 20 may be, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate. The thickness of the release film 20 is, for example, 10 to 50 μm.

The laminates 100 to 103 can be bonded to a display element (eg, a liquid crystal cell, an organic EL element) by peeling the release film 20. Additionally, the surface protection film 30 can be peeled off and incorporated into a display device (eg, a liquid crystal display device, an organic EL display device). When constructing a display device, the laminate according to the present invention may be used for a polarizing plate disposed on the viewer side with respect to the display element, or may be used for a polarizing plate disposed on the opposite side from the viewer side, and may be used on the viewer side and the viewer side. may be used for both polarizing plates on opposite sides.

<Method for manufacturing laminate>

The laminate may be obtained by manufacturing a long laminate by roll-to-roll while transporting each member constituting the laminate and cutting it, or by preparing each member of a predetermined shape and stacking them sequentially. It's also good.

Cutting processing, hole drilling processing, and corner R processing can be performed using planing processing, end mill processing, etc. It is preferable that the processing means for cutting and drilling is an end mill. An end mill is a type of cutting tool. Unlike drills, which only perform processing in the axial direction (only for drilling holes), end mill processing can also be performed in a direction perpendicular to the rotation axis. Planing refers to processing in which the machined surface is shaved in parallel using a protruding blade having a rotation axis parallel to the machined surface. Specifically, the processing device and processing method described in Japanese Patent Application Laid-Open No. 2018-22140 can be adopted.

<Method for manufacturing polarizer with surface protection film>

A method of peeling the release film from the laminate 104 will be described using FIG. 5 as a specific example. The surface of the laminate on the surface protection film side is fixed to a support table, and the tape 200 is bonded onto the release film. The method of fixing the laminate 104 is not particularly limited, and may be fixed by a suction force from the surface protection film side, or may be fixed by adhesive force. The adhesion between the fixing surface protection film and the support is preferably 0.1 to 0.3 N/60 mm, and more preferably 0.15 to 0.2 N/60 mm, from the viewpoint of preventing traces from being left on the polarizing plate. According to the laminate of the present invention, good peelability is exhibited even when the laminate is fixed with such a small pressure. The position where the tape 200 is joined may be, for example, a corner portion of one end of a short side having a cutout portion, as shown in FIG. 5 .

Subsequently, the tape 200 is raised and the release film is peeled. In Figure 5, the angle θ formed between the short side orthogonal to the short side having the cutout and the peeling direction 400 of the tape may be 0° or more and 90° or less. When the peeling film is peeled by attaching a tape to the corner of one end of the short side having the cutout, peeling occurs when the peeling tip reaches the cutout, especially when the peeling tip reaches the area 300 shown in FIG. 5. Defects are likely to occur. That is, the peeling tip is the inner corner of the notch, and peeling defects are likely to occur when it reaches the inner corner farther from the position where the tape is attached. According to the present invention, peeling defects are unlikely to occur even when the peeling tip reaches the notch. In order to reduce the force that peels off the release film in the region 300, the angle θ is preferably 25° or more and 65° or less. Additionally, the peeling angle can be 90 to 180°, and the peeling speed can be 0.1 to 10 m/min.

[Example]

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

(1) Method of measuring film thickness

Measurements were made using a digital micrometer, MH-15M, manufactured by Nikon Corporation.

(2) Method of measuring adhesion

The adhesion between the release film and the adhesive layer provided on the polarizing plate was measured using Autograph (registered trademark) AGS-X, a tabletop precision universal tester manufactured by Shimazu Seisakusho Co., Ltd.

(3) Peeling force of the peeling film

The laminate produced in each example was fixed to a glass plate (support) so that the surface protection film was on the lower side. An adhesive sheet was used for fixation, and the fixing force (adhesion force) was 0.1 to 0.3 N/60 mm. As shown in FIG. 5, the tape was bonded to one corner of the short side having the notch so that the long side direction of the tape was parallel to the long side direction of the laminate. The tape was No. 1, a polyester adhesive tape manufactured by Nitto Denko Co., Ltd. 315 was used, the width was 12 mm, and the length of the joined portion was 10 mm. One end of the tape was held by a chuck, and the release film was peeled. The angle formed by the peeling direction of the tape and the short side orthogonal to the short side having the notch (angle (θ) in FIG. 5) was 45°. The peeling speed was 3 m/min, and the peeling angle was 180°. The peeling force while peeling the release film was measured, and the maximum value of the peeling force was determined.

(4) Method for evaluating peelability of release film

The laminate produced in each example was fixed to a glass plate (support) so that the surface protection film was on the lower side. An adhesive sheet was used for fixation, and the fixing force (adhesion force) was 0.1 to 0.3 N/60 mm. As shown in FIG. 5, the tape was bonded to one corner of the short side having the notch so that the long side direction of the tape was parallel to the long side direction of the laminate. The tape was No. 1, a polyester adhesive tape manufactured by Nitto Denko Co., Ltd. 315 was used, the width was 12 mm, and the length of the joined portion was 10 mm. One end of the tape was held with a chuck, and the release film was peeled. The angle formed by the peeling direction of the tape and the short side orthogonal to the short side having the notch (angle (θ) in FIG. 5) was 45°. The peeling speed was 3 m/min, and the peeling angle was 180°. At this time, the case where the layer consisting of the polarizing plate and the surface protection film floated from the glass on which the laminate was fixed was judged to be peeling defective (NG), and the case where the peeling film could be peeled without floating was judged to be good peeling (OK). It was decided.

[Production of laminate]

A polarizer (thickness 8 ㎛) in which iodine was adsorbed and oriented on a polyvinyl alcohol-based resin was produced.

A cyclic olefin resin (COP) film (thickness 25 µm) with a hard coat layer formed on it is bonded to one side of the polarizer via an ultraviolet curable adhesive, and to the other side of the polarizer, a tri-curable film is bonded through the same adhesive. Acetylcellulose (TAC) film (thickness 20 ㎛) was bonded.

Subsequently, a retardation film including a layer in which the polymerizable liquid crystal compound was cured was prepared. This retardation film has a layer structure in which a λ/4 plate (thickness 2 μm) and a positive C plate (thickness 3 μm) are laminated through an ultraviolet curable adhesive (thickness 2 μm). The retardation film and the TAC film were bonded through an adhesive layer (5 μm thick) so that the λ/4 plate and the TAC film were bonded surfaces to each other.

On the positive C plate, an acrylic adhesive layer (25 μm thick) formed on the release film was laminated. On the COP film, a base film made of polyester resin and a surface protection film made of an acrylic adhesive layer were laminated.

The obtained film was cut into a rectangle with a long side of 150 mm and a short side of 70 mm. The long side direction was parallel to the absorption axis of the polarizer. The laminate had a layer structure of release film/adhesive layer/retardation layer (including two layers in which the liquid crystal compound was cured)/TAC film/polarizer/COP film with hard coat layer/surface protection film. The thickness of the polarizing plate was 80 μm, the thickness of the release film was 38 μm, and the thickness of the surface protection film was 53 μm.

The adhesive force between the adhesive layer and the release film was 0.02 N/25 mm, and no peeling was observed between the adhesive layer and the release film due to conveyance or the like.

[Example 1]

Notch processing was performed on one short side of the laminate by end milling. As for the shape of the notch, the depth d was set to 2 mm, and the radius of curvature r of the two inner corners was set to 2 mm. The shape of the notch was the shape shown in Fig. 4(d) when viewed from the top.

[Examples 2 to 15, Comparative Examples 1 to 11]

Cutting processing was performed on the laminate in the same manner as in Example 1, except that the shape of the cutout portion was as shown in Table 1.

[Comparative Example 12]

A notch was formed by cutting one short side of the laminate with a knife. R processing was not performed on the two inner corners, and the two inner corners were each at a right angle.

For the laminates produced in Examples 1 to 15 and Comparative Examples 1 to 11, the maximum peel force was measured and peelability was evaluated. The results are shown in Table 1. As shown in Table 1, the laminates of Examples 1 to 15 were able to peel the release film satisfactorily. Additionally, in any of the examples, the defect of peeling between the polarizing plate and the surface protection film did not occur. The release films of the laminates of Comparative Examples 1 to 12 could not be easily peeled. The maximum peeling force of Comparative Example 12 was more than 1.0 N. On the other hand, in any laminate, the maximum value of peeling force was recorded when the peeling tip reached the area 300 shown in FIG. 5. That is, the peeling tip is the inner corner of the notch, and the maximum value of the peeling force was recorded when it reached the inner corner farther from the position where the tape was attached.

The present invention is useful because it can provide a laminate in which peeling defects of the peeling film do not occur.

10: Polarizer 11: Polarizer
12: protective film 13: protective film
14: Retardation film 15: Adhesive layer
16: Adhesive layer 17: Brightness improvement film
20: release film 30: surface protection film
31: Base film 32: Adhesive layer
40: notch 100: laminate
101: Laminate 102: Laminate
103: Laminate 104: Laminate
200: release tape 300: area
400: Peeling direction

Claims (4)

A surface protection film is laminated on one side of the polarizer,
A release film is laminated on the other side of the polarizer,
The polarizing plate includes a polarizer,
The polarizing plate is a laminate having an adhesive layer on a surface on the release film side,
The adhesion between the release film and the adhesive layer is 0.02 N/25 mm or more and 0.10 N/25 mm or less,
The laminate has a notch when viewed from the top,
When the depth of the cutout is d (mm) and the radius of curvature of the inner corner of the cutout is r (mm),
d is 2 mm or more and 20 mm or less,
When d is 2 mm or more and 5 mm or less, r is 2 mm or more,
When d is greater than 5 mm and less than or equal to 6 mm, r is greater than or equal to 8 mm,
When d is greater than 6 mm and less than 8 mm, r is greater than or equal to 13 mm,
When d is 8 mm or more, r is 17 mm or more,
A laminate in which the maximum value of the peeling force is 1.0 N or less when the peeling film is peeled from the short side having the cutout portion. The laminate according to claim 1, wherein the shape of the notch satisfies the following equation (1).
r>3d-14 (1)
[In equation (1), d (mm) represents the depth of the notch, and r (mm) represents the radius of curvature of the inner corner of the notch.] In the laminate according to claim 1 or 2, a sticking step of attaching a tape to one corner of a short side having a notch;
A peeling step is provided to raise the tape and peel the release film from the laminate,
In the peeling process, the angle formed between the peeling direction of the tape and the short side orthogonal to the short side having the cutout is 25° or more and 65° or less. delete