WO2011016572A1

WO2011016572A1 - Method for manufacturing polarizing plate

Info

Publication number: WO2011016572A1
Application number: PCT/JP2010/063439
Authority: WO
Inventors: 松本力也; 及川伸; 植田幸治
Original assignee: 住友化学株式会社
Priority date: 2009-08-06
Filing date: 2010-08-02
Publication date: 2011-02-10
Also published as: CN102282485B; JP2011053673A; TWI367353B; KR20110089375A; CN102282485A; KR101102159B1; JP4743339B2; TW201118437A

Abstract

Disclosed is a method for manufacturing a polarizing plate including both a film having a high laser-beam absorption rate and a film having a low laser-beam absorption rate, in which a strip-shaped polarizing plate is cut, leaving only a peeling film layer formed on the surface to be bonded to a substrate. The method for manufacturing the polarizing plate comprises: cutting from the upper surface of a surface protection film layer down to a layer immediately above a layer formed of the film having a low laser-beam absorption rate by using a laser; and subsequently cutting the layer formed of the film having a low laser-beam absorption rate and an adhesive layer by using a cutter. According to the method for manufacturing the polarizing plate, a delamination does not occur between a polarizer protection film layer and a surface protection film layer both constituting the polarizing plate and a contamination due to the adhesive running off from the cutting surface does not also occur, so that it is possible to obtain a polarizing plate excellent in close-bonding property with respect to a substrate.

Description

Manufacturing method of polarizing plate

The present invention relates to a method for producing a polarizing plate used in an image display device such as a liquid crystal display device and a polarizing plate cut by the method. Specifically, the present invention relates to a method for producing a polarizing plate including both a layer made of a laser light high absorption rate film and a layer made of a low absorption rate film, and a polarizing plate cut by the method.

Liquid crystal display devices have been used for desktop computers and electronic clocks in the past, but in recent years, their applications are expanding rapidly. That is, liquid crystal display devices have been used from mobile devices such as mobile phones to large televisions regardless of screen size. In addition to liquid crystal display devices, organic electroluminescence (organic EL) display devices also tend to increase mainly in mobile applications. Therefore, the demand for polarizing plates used in these image display devices is also increasing, and performance suitable for each application is required.

A polarizing plate that is widely used in the image display device as described above is formed on a polarizer layer 1 in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film via a liquid adhesive layer. It is manufactured with a structure in which a polarizer protective film layer represented by an acetylcellulose film is laminated. In this state, or if necessary, with a function such as a circular / elliptic polarizing plate or retardation plate having optical properties via an adhesive layer, a surface antireflection / antiglare material, a light diffusing plate, a reflecting plate, An image display device is obtained by bonding to an image display element such as a liquid crystal cell or an organic EL display element. The polarizing plate is polarized light on the bonding surface side with the image display element for the purpose of preventing the surface of the polarizer protective film layer or the function-added film layer from being scratched or contaminated before being bonded to the image display element. A structure in which the surface of the child protective film layer or the function-added film layer is bonded to the release film layer via an adhesive layer, and the surface of the other polarizer protective film layer is bonded to the surface protective film layer via an adhesive layer It has become.

FIG. 4 shows the layer structure of the conventionally used polarizing plate. That is, the polarizing plate 12 shown in FIG. 4 includes a surface protective film layer 4, an adhesive layer 3, a polarizer protective film layer 2, a polarizer layer 1, a polarizer protective film layer 2a, a function-added film layer 5, and an adhesive layer. 6, composed of a release film layer 7. In such a configuration, the function-added film layer is a film layer that is optionally selected and used, and is not essential.

In recent years, in an image display apparatus for mobile use such as a mobile phone, the entire module has been made thinner and slimmer from the viewpoint of design and portability. Therefore, since a further reduction in thickness and weight is desired for the polarizing plate as the image display device material, as shown in FIG. 1, the polarizer protective film of the conventional polarizing plate shown in FIG. It has also been proposed to use a polarizing plate without the polarizer protective film layer 2a by using a function-added film layer that also has a layer function.
That is, the strip-shaped polarizing plate shown in FIG. 1 is composed of the surface protective film layer 4, the pressure-sensitive adhesive layer 3, the polarizer protective film layer 2, the polarizer layer 1, the function-added film layer 5, the pressure-sensitive adhesive layer 6, and the release film layer 7. Composed. A cycloolefin film is known as a film to which such a function is added.

A polarizing plate is usually provided in the form of a roll of a strip-like film stretched in the longitudinal direction. As a method of attaching the polarizing plate to an image display element or the like, a strip shape is previously adjusted to the size of the image display element such as a liquid crystal substrate. After the polarizing plate is cut, the polarizing plate pieces are bonded to the image display element one by one. In such a method, when the polarizing plate piece is bonded to the image display element, it is necessary to transfer the polarizing plate pieces one by one immediately before the bonding, and to peel the release film from the polarizing plate piece. There is a limit to shortening the process time. Moreover, since the polarizing plate piece is usually punched from a roll-shaped polarizing film, curling is likely to occur, and workability when transferring and transporting the polarizing plate piece is poor. Furthermore, when an LCD is used as an image display device, the polarizing plate is disposed with the transmission axis of the polarizing plate inclined by 45 ° with respect to the vertical or horizontal direction of the LCD screen. It is necessary to punch in the direction of 45 ° in advance with respect to the direction, and there are many portions that cannot be used near the end of the roll. In particular, when a large-size polarizing plate is used with an increase in the screen size of the LCD, there is a problem that the yield is reduced. Moreover, since the piece of the polarizing plate which was not used for pasting is used in combination with a plurality of materials, it is difficult to reuse, resulting in an increase in waste.

In recent years, as a means for solving such problems, a strip-like film in which a release film layer is stuck on a strip-like polarizing plate via an adhesive layer corresponds to a cut surface on the traveling direction side perpendicular to the longitudinal direction of the strip-like film. When the film has traveled up to a length, the strip film is cut by the cutting, cutting means for cutting at least the strip polarizing plate and the adhesive layer in a direction perpendicular to the longitudinal direction, leaving the release film layer. Release film separating means for separating the release film layer from the film piece, an adhesive surface of the film piece from which the release film layer is separated, an end surface on the traveling direction side of the substrate that has been conveyed, and a cut surface of the film piece A polarizing plate laminating apparatus for laminating a polarizing plate on a substrate is disclosed, which includes a laminating means for laminating at a corresponding position on the substrate so that they are parallel to each other (example) If JP2005-37416-A).

According to the method, etc., the polarizing plate can be continuously and automatically bonded to the image display element, and there is no need to transfer the cut polarizing plate, and the release film layer is not cut. It is a method that can be bonded at a high speed and does not produce unnecessary cut pieces of the polarizing plate. In this method, when the strip-shaped polarizing plate is cut, it is an essential requirement that only the release film layer is left and the polarizing plate is cut (hereinafter sometimes referred to as half cut). As such cutting means, it is known to use a press-cut type cutter and a dicing type cutter, and provide a cutter blade, a cylinder for driving the cutter blade, and a bottom dead center position adjusting member for adjusting the bottom dead center position of the cutter blade. ing. However, cutting with a cutter blade makes the cutting section beautiful if the edge angle is sharpened, but the life of the cutter blade is short.On the other hand, when the edge angle becomes obtuse, the adhesive or adhesive sticks out in the cutting section, and Problems such as contamination of the bonded product occur at the time of bonding, and there is a difference in degree depending on the angle of the cutter blade to be used, but when using a cutter, the polarizing plate on the cut surface of the polarizing plate The surface protective film layer on the polarizer protective film layer to be formed has a drawback that it adversely affects the physical properties of the polarizing plate, such as lowering the moisture resistance.

In the conventional method in which the polarizing plate pieces are bonded to the image display element one by one after cutting the band-shaped polarizing plate according to the size of the image display element such as the liquid crystal substrate in advance, the problem that occurs in the cutting method using the cutter blade described above In other words, the protrusion of the adhesive or pressure-sensitive adhesive, and the surface protective film layer floating on the photon protective film layer, after cutting, after removing the defective part by processing the polarizer layer cut end face in advance, image It can be bonded to a display element. However, in the above half-cut method, it is difficult to process the cut surface in advance in a continuous process after cutting, and therefore a cutting method without such a defect is necessary.

On the other hand, a method of cutting a strip-shaped polarizing plate using a laser is also known. For example, JP2008-284572-A describes that a strip-shaped polarizing plate can be cut by irradiating a laser beam. Specifically, a pair of triacetyl cellulose (TAC) film layers are bonded to both sides of a polyvinyl alcohol (PVA) film layer, and further, one TAC film layer side is made of polyethylene terephthalate via an acrylic adhesive layer. A separator made of a tartrate (PET) film is provided, and on the other TAC film layer side, a belt-like polarizing plate provided with a surface protective film layer made of a PET film is irradiated with laser light via an acrylic pressure-sensitive adhesive layer. By cutting.

The band-shaped polarizing plate to be cut in JP2008-284572-A is a film having a high average absorption rate of laser light (hereinafter referred to as “Plasma film”, “TAC film”, “PET film”, etc.). For example, a film having a higher average absorption rate than 2% is laminated. The laminated polarizing plate made of such a laser light high absorption rate film can be cut well by a conventional method as shown in JP2008-284572-A without causing the cutting surface of the polarizing plate to be deformed. .

However, in the method shown in JP2008-284572-A, in addition to the laser light high absorption rate film, a laser in the oscillation wavelength range of the irradiated laser light such as cycloolefin polymer film, polypropylene film, polymethyl methacrylate film, etc. When cutting a film having a low average light absorptivity (hereinafter sometimes referred to as “laser light low absorptivity film”), for example, a band-shaped polarizing plate including a layer made of a film having an average absorptance of 2% or less When the output of the laser beam is small, the layer made of the laser beam high absorptivity film of the band-shaped polarizing plate can be cut, but the layer made of the laser beam low absorptivity film cannot be cut. On the other hand, when the output of the laser light is increased, it is possible to cut not only the layer made of the laser light high absorption rate film of the belt-like polarizing plate but also the layer made of the laser light low absorption rate film. However, in this case, excessive heat is applied to the layer made of the laser light high absorption rate film, so that the end of the cut polarizing plate is melted and the cut end is deformed (see FIG. 6). A polarizing plate having a deformed cut surface has a reduced cross-sectional quality. Furthermore, various problems may occur due to the deterioration of the cross-sectional quality. For example, when a polarizing plate is bonded to a glass substrate, high adhesion is required. However, there is a problem that air bubbles are caught in the bonding surface with the glass substrate due to the unevenness of the cut surface of the polarizing plate.

In addition, in a strip-shaped polarizing plate including a layer made of a laser light low absorption film, when cutting the layer made of the laser light low absorption film by increasing the output of the laser light, the laser light low absorption film is used. Since the release film layer located under the layer is usually composed of a laser light high absorption rate film, the release film layer is cut before the laser light low absorption rate film is melt cut. For this reason, it is considered that the application of the laser method is extremely difficult in the so-called half-cut type cutting method in which only the release film layer is left and all the film layers constituting the other polarizing plate need to be cut.

Therefore, the present inventors include both a layer composed of a laser light high absorption film and a layer composed of a laser light low absorption film, and a strip-shaped polarizing plate comprising a release film layer composed of a laser light high absorption film, In the manufacturing method of the polarizing plate that cuts the film layer and the pressure-sensitive adhesive layer constituting the other polarizing plate leaving only the release film layer, it is substantially between the polarizer protective film layer and the surface protective film layer constituting the polarizing plate after cutting. The adhesive layer and adhesive layer do not protrude from the cut surface, and the cutter blade has a long service life. Exactly leaves only the release film, and cuts the film and adhesive layers that make up other polarizing plates. As a result of intensive studies to find a possible method, the present invention has been completed.

The present invention includes the following.
[1] A polarizer protective film layer made of a laser light high absorptivity film is laminated on one surface of a polarizer layer made of a polyvinyl alcohol-based resin film, and the surface of the polarizer protective film layer opposite to the polarizer layer A surface protective film layer made of a laser light high absorption rate film is laminated on the adhesive layer, and the other side of the polarizer layer is made of a layer made of a laser light low absorption rate film via an adhesive, and the A strip-shaped polarizing plate in which a release film layer made of a laser light high absorption rate film is laminated via an adhesive layer on the surface opposite to the polarizer layer of the layer made of a laser light low absorption film, leaving only the release film. A method of manufacturing a polarizing plate including cutting a layer constituting another polarizing plate, from a surface protective film layer to a layer immediately before a layer made of a laser light low absorption film. A method of cutting with a cutter a layer made of a laser light low absorption film and an adhesive layer after cutting with a laser.

[2] The laser light low absorption rate film is a film having an average absorption rate of laser light of 2% or less, and the laser light high absorption rate film is a film having an average absorption rate of laser light exceeding 2% [1. ] Method.

[3] The method according to [2], wherein the laser light low absorption rate film is a film having an average absorption rate of laser light of 1% or less.

[4] The method according to any one of [1] to [3], wherein a polarizer protective film layer made of a laser light high absorption film is provided between the polarizer layer and the layer made of a laser light low absorption film.

[5] The method according to any one of [1] to [4], wherein the laser light low absorption rate film is a cycloolefin polymer film, a polypropylene film, or a polymethyl methacrylate film.

[6] The method according to any one of [1] to [5], wherein the laser is a carbon dioxide laser.

[7] A polarizing plate produced by the method according to any one of [1] to [6].

According to the method for manufacturing a polarizing plate of the present invention, a so-called half-cut method in which a strip-shaped polarizing plate is cut leaving only a release film is employed, and the polarizing plate includes both a laser light high absorption rate film and a low absorption rate film. In this case, the surface protective film layer on the polarizer protective film layer constituting the polarizing plate is not substantially lifted on the cut surface of the polarizing plate after the strip-shaped polarizing plate cutting treatment, and the adhesive is not protruded on the cut surface. It is possible to cut a layer consisting of a surface protective film layer, a polarizer layer, and a laser light low absorptivity film, leaving a release film layer on, and since it is used in combination with a laser, the life of the cutter blade used for cutting will be extended. Has an effect.

It is a cross-sectional schematic diagram which shows an example of the layer structure of the strip | belt-shaped polarizing plate reduced in weight applied to this invention. It is a cross-sectional schematic diagram which shows an example of the laminated constitution of the strip | belt-shaped polarizing plate applied to this invention. It is a cross-sectional schematic diagram by the two-stage cutting | disconnection of this invention. It is a cross-sectional schematic diagram which shows an example of the laminated constitution of the polarizing plate applied with the conventional method. 2 is a photomicrograph of a cut surface of a polarizing plate cut by the method of the present invention obtained in Example 1. FIG. It is a microscope picture of the cut surface of the polarizing plate cut | disconnected only using the fixed round blade. 2 is a micrograph of a fixed round blade after cutting a polarizing plate used in Comparative Example 1. 2 is a micrograph of a fixed round blade after cutting a polarizing plate used in Comparative Example 1.

Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of a strip-shaped polarizing plate used in the method for producing a polarizing plate of the present invention. In FIG. 1, the band-shaped polarizing plate has a polarizer protective film layer 2 on one surface of the polarizer layer 1 via an adhesive layer (not shown), and a surface opposite to the polarizer layer of the polarizer protective film layer 2 ( A laser having a surface protecting film layer 4 on the upper surface via an adhesive layer 3 and a laser having a polarizer protecting function and a phase difference ability on the other surface of the polarizer layer 1 via an adhesive layer (not shown). A layer 5 composed of a low light absorptivity film, an adhesive layer 6 and a release film layer 7 are laminated in this order. FIG. 2 is a schematic cross-sectional view showing an example of the layer structure of another strip-shaped polarizing plate used in the method for manufacturing a polarizing plate of the present invention. In FIG. 2, the strip-shaped polarizing plate has a polarizer protective film layer 2 on one surface of the polarizer layer 1 and an opposite surface (upper surface) of the polarizer protective film layer 2 through an adhesive layer (not shown). ) Is provided with a surface protective film layer via an adhesive layer 3, and the other surface of the polarizer 1 is provided with a polarizer protective film layer 2 a and an adhesive layer (not shown) via an adhesive layer (not shown). A layer 5, a pressure-sensitive adhesive layer 6, and a release film layer 7 made of a laser light low absorptivity film having retardation are laminated in this order.

In the practice of the present invention, the strip-shaped polarizing plate is usually provided in the form of a roll of a strip-shaped film stretched in the longitudinal direction, and the strip-shaped polarizing plate is cut in advance according to the size of the image display element, leaving only the release film layer 7. The release film layer is peeled off from the plate, and the polarizing plate pieces are laminated on the image display element one by one. As a means for cutting the polarizing plate into the desired size of the image display element while leaving only the release film layer from the belt-like film, first, in the case of the belt-like polarizing plate shown in FIG. 4, in the case of the pressure-sensitive adhesive layer 3, the polarizer protective film layer 2, the polarizer layer 1, the adhesive layer (not shown), or the strip-shaped polarizing plate shown in FIG. 2, the uppermost surface protective film layer 4, After the adhesive layer 3, the polarizer protective film layer 2, the polarizer layer 1, the polarizer protective film layer 2a, and the adhesive layer (not shown) are cut with a laser, the layer 5 made of a laser light low absorption film and The adhesive layer 6 is cut with a cutter.

The polarizer layer 1 used in the present invention is a film having a function of extracting linearly polarized light from incident natural light, and a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film can be used. The average absorption rate of laser light of the film is greater than 2%, for example, about 6%. The polyvinyl alcohol-based resin constituting the polarizer layer 1 can be obtained by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

A film obtained by forming such a polyvinyl alcohol resin is used as an original film of a single polarizer. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. The film thickness of the raw film made of polyvinyl alcohol resin is not particularly limited, but is, for example, about 1 to 150 μm. Considering easiness of stretching, the film thickness is preferably 10 μm or more.

The polarizer layer 1 is a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of dyeing the polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, and a dichroic dye adsorbing It is manufactured through a step of treating the polyvinyl alcohol resin film thus obtained with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. As the dichroic dye, iodine or a dichroic organic dye is used.

The polarizer protective film layers 2 and 2a used in the present invention are made of a laser light high absorptivity film, and the average absorptance of the laser light is usually larger than 2%, and can be composed of an appropriate transparent film. Among them, a film made of a resin excellent in transparency, optical property uniformity, mechanical strength, thermal stability, etc. is preferably used. For example, cellulose resin films such as triacetyl cellulose and diacetyl cellulose, polyester resin films such as polyethylene terephthalate, polyethylene isophthalate and polybutylene terephthalate, polycarbonate resin films, polyether sulfone resin films, polysulfone resin films, polyimides Based resin film, and the like. Lamination of the transparent protective film layers 2 and 2a to the polarizer layer 1 is performed through an adhesive layer, and an adhesive known in the art can be used, and the known adhesive is irradiated with laser light. The average absorptance of the laser light in the oscillation wavelength range is high and is usually larger than 2%.

Examples of such adhesives include water solvent adhesives, organic solvent adhesives, hot melt adhesives, and solventless adhesives. More specifically, examples of the aqueous solvent-based adhesive include a polyvinyl alcohol-based resin aqueous solution and an aqueous two-component urethane emulsion adhesive, and examples of the organic solvent-based adhesive include a two-component urethane adhesive. Examples of the solvent-based adhesive include a one-pack type urethane-based adhesive. When an acetylcellulose-based film whose surface bonded to a polarizer is hydrophilized by saponification or the like is used as a polarizer protective film, a polyvinyl alcohol-based resin aqueous solution is suitably used as an adhesive. Polyvinyl alcohol resins used as adhesives include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as other single quantities copolymerizable with vinyl acetate. And vinyl alcohol copolymers obtained by saponifying the copolymer with the polymer, and modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups. For this adhesive, a polyvalent aldehyde, a water-soluble epoxy compound, a melamine compound or the like may be used as an additive.

The polarizing plate in the present invention uses a laser light low absorption rate film as a constituent layer material of the polarizing plate. The average absorptance of the laser light in the oscillation wavelength range of the irradiated laser light is usually 2% or less, preferably 1% or less. In this specification, the “average absorption rate (%) of laser light in the oscillation wavelength range of irradiated laser light” can be measured using a conventionally known ATR (Attenuated total reflection) method. The “ATR method” refers to the absorption spectrum on the surface of the measurement object by irradiating the measurement object with light (laser light) having an arbitrary wavelength and measuring the light totally reflected on the surface of the measurement object. How to get. By measuring the absorptance of light having an arbitrary wavelength within the oscillation wavelength range of the irradiated laser light using the ATR method, and calculating the average value of the obtained absorptance, the “irradiated” The average absorption rate (%) of the laser beam in the oscillation wavelength range of the laser beam can be obtained.

Examples of such a low laser light absorption film include acrylic resin films such as polymethyl (meth) acrylate and polyethyl (meth) acrylate, polyolefin resin films, and cyclic olefin resin films containing cyclic olefins such as norbornene as monomers. More specifically, a cycloolefin polymer (COP) film, a polypropylene (PP) film, a polymethyl methacrylate (PMMA) film, etc. can be mentioned. These films have not only the retardation film function required for polarizing plates but also excellent water absorption prevention and moisture resistance prevention functions, so that a polarizer protective film such as TAC is used like a strip-like polarizing plate shown in FIG. It is also possible to use instead.

In addition, the polarizing plate in the present invention is further provided with a surface protection film function-added film layer such as a retardation film layer, a viewing angle widening film layer, an antireflection film layer, an antiglare film layer, and a reflection film layer, depending on the purpose. You may have in either between the layer which consists of a film layer and a laser beam low absorption rate film, and this function addition film layer is comprised with the laser beam high absorption rate film. These may be used as a single layer or a plurality of layers.

In the present invention, a pressure-sensitive adhesive used in the field can be used as the pressure-sensitive adhesive used for the pressure-sensitive adhesive layers 3 and 6 forming the polarizing plate. The known pressure-sensitive adhesive has a high average absorption rate of the laser beam in the oscillation wavelength range of the irradiated laser beam, and is usually larger than 2%. For example, those having a base polymer such as acrylic, rubber, urethane, silicone, and polyvinyl ether are used. Moreover, an energy beam curing type, a thermosetting type, etc. may be sufficient. Among these, a pressure-sensitive adhesive having an acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is preferable.

The acrylic pressure-sensitive adhesive is not particularly limited, but (meth) acrylate such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, (2-ethylhexyl (meth) acrylate) ) An acrylic ester base polymer and a copolymer base polymer using two or more of these (meth) acrylic esters are preferably used. Furthermore, polar monomers are copolymerized in these base polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having a carboxy group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as acrylate and glycidyl (meth) acrylate.

These acrylic pressure-sensitive adhesives can of course be used alone, but a crosslinking agent is usually used in combination. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples thereof include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are widely used as organic crosslinking agents.

The energy ray curable adhesive has the property of curing upon irradiation with energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before irradiation with energy rays and adheres to adherends such as films. It is a pressure-sensitive adhesive that adheres and is cured by irradiation with energy rays and has the property of adjusting the adhesion. In addition, when a curable adhesive is used for an adhesive layer in this invention, an adhesive layer means the layer which consists of hardened | cured material of a curable adhesive. As the energy ray curable adhesive, it is particularly preferable to use an ultraviolet curable adhesive. The energy beam curable pressure-sensitive adhesive generally comprises an acrylic pressure-sensitive adhesive and an energy beam polymerizable compound as main components. Usually, a crosslinking agent is further blended, and if necessary, a photopolymerization initiator, a photosensitizer, and the like can be blended.

In addition to the above base polymer and crosslinking agent, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer includes, as necessary, the pressure-sensitive adhesive strength, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. In order to adjust, for example, natural or synthetic resins, tackifying resins, antioxidants, dyes, pigments, antifoaming agents, corrosive agents, photopolymerization initiators, and other appropriate additives are added. You can also. Furthermore, it can also be set as the adhesive layer which contains microparticles | fine-particles and shows light-scattering property. The pressure-sensitive adhesive layer may contain an antioxidant or an ultraviolet absorber. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

In the present invention, the release film layer 7 constituting the polarizing plate is a release material made of a laser light high absorption rate film, and the average absorption rate of the laser light in the oscillation wavelength range of the irradiated laser light is usually larger than 2%. Consists of. Conventional release materials used for optical films, such as polyethylene terephthalate films and polyester films, are used.

The substrate 8 of the display device to which the polarizing plate is bonded after peeling the release film layer 7 is a flat plate member such as a glass substrate or a synthetic resin substrate used in a display device such as a liquid crystal display device or a plasma display device. A substrate on which components such as a liquid crystal cell and an electrode are formed in advance may be used. As the shape of the substrate, a shape such as a square or a rectangle is generally used.

As a laser device used for cutting the strip-shaped polarizing plate in the present invention, it is possible to use a generally known infrared laser, such as a carbon dioxide laser, a YAG laser, a UV laser, etc., but there are few cracks or chips on the cut surface, Application of carbon dioxide laser is recommended from the viewpoint of workability.

The cutting speed by the laser depends on the thickness of the strip-shaped polarizing plate to be cut, but is 1 m / min or more, preferably 5 to 60 m / min if the polarizing plate has a thickness of 70 to 500 μm. If the cutting speed is less than 1 m / min, the productivity tends to be inferior. The output of the infrared laser is usually used in the range of 10 W to 400 W, although it depends on the thickness of the polarizer, the desired cutting speed, and the like. The laser wavelength used in the present invention is a polarizing plate including a layer composed of a laser light low-absorption film that is irradiated only on one side of the polarizer targeted by the present invention, particularly in the cutting process of a thin strip-shaped polarizing plate, It is recommended to use a laser with a laser wavelength of 9.4 μm. In the case of cutting using such a laser wavelength, the cut end face is beautiful as compared with, for example, a cutting process using a laser wavelength of 10.6 μm.

As shown in FIG. 3, the cutting with the laser is performed from the surface protective film layer constituting the strip-shaped polarizing plate to the layer immediately before the layer 5 made of the laser light low absorption rate film. In the case of cutting only the release film layer 7 and cutting to the layer 5 made of a laser light low absorption rate film and the adhesive 6, the layer 5 made of the laser light low absorption rate film has a low light absorption capability, so that the laser It is difficult to perform cutting with good dimensional accuracy (adjustment of the cutting depth), and in most cases, it is difficult to cut the release film and make the desired half-cut. Moreover, even if it can be half-cut, since the resin melts and becomes a lump, the release film layer 7 is peeled off from the cut polarizing plate and bonded to the substrate 8. Floating occurs and cannot be evenly adhered.

In the present invention, a strip-like polarizing plate obtained by cutting the layer 5 immediately before the layer 5 made of such a laser light low absorption film with a laser is cut using a cutter, leaving the release film layer 7. By adopting such a method, the surface protection film 4 is lifted and the adhesive sticks out when all the band-shaped polarizing plates are cut with a cutter, and further, the production cost resulting from a remarkably short cutter life is improved. Work that requires complicated and advanced technology that requires only the release film layer to be cut, rather than a polarizing plate with a protective film layer or release film layer with significantly different light absorption capabilities that occurs when the polarizing plate is cut. Is solved by adopting a very simple method of performing the cutting operation in two stages.

The cutter that cuts the layer 5 and the adhesive layer made of the laser light low absorption film may be any cutter that is usually used in the field of optical films. For example, a press-cut cutter, a dicing cutter, a fixed round blade, A rotating round blade is exemplified. It is recommended to use a cutter blade that includes a cylinder that drives the cutter blade and a bottom dead center position adjusting member that adjusts the bottom dead center position of the cutter blade. In this case, the bottom dead center position is adjusted to 0.5 times or less of the thickness of the release film layer 7 to leave the release film 7 accurately, and the layer 5 and the adhesive layer made of a laser light low absorption rate film. Can be cut in a direction perpendicular to the longitudinal direction of the film.

In addition, when the average absorptance of a typical film applied to the polarizing plate in the range of the emission wavelength of the carbon dioxide gas laser (9.2 μm to 10.8 μm) was measured, a triacetyl cellulose film (TAC film): 13% , Polyvinyl alcohol (PVA film): 6%, polyethylene terephthalate film (PET film): 8%, cycloolefin polymer film (COP film): 0.3%, polymethyl methacrylate film (PMMA film): 0.8%, Polypropylene film (PP film): 0.7%.

As described above, the polarizing plate cut into a desired shape by the method of the present invention described in detail above is bonded onto the substrate 8 such as a liquid crystal display after the release film layer 7 is peeled off. In these operations, a belt-shaped film laminated in the structure shown in FIG. 1 or FIG. 2 is wound in a roll shape, the roll-shaped film is drawn out in the longitudinal direction, and the cut surface on the traveling direction side orthogonal to the longitudinal direction is provided. A cutting step of cutting at least the strip-shaped polarizing plate and the adhesive layer in a direction perpendicular to the longitudinal direction, leaving the stripping film layer, when cut to a length corresponding to the substrate, and cutting by the cutting A separation step of separating the release film layer from the released film piece, a bonding step of bonding the adhesive surface of the film piece from which the release film layer has been separated to the substrate that has been transported, and polarization to a substrate It is recommended to apply as a polarizing plate laminating device for laminating plates continuously.

Hereinafter, based on an Example, this invention method is demonstrated in detail.
[Production of polarizing plate]
In the present example, a strip-shaped polarizing plate having a structure substantially shown in FIG. 1 was used. That is, the polarizer protective film layer 2 made of a triacetyl cellulose film having a thickness of 80 μm is coated with polyvinyl alcohol and a water-soluble epoxy resin on both sides of the polarizer layer 1 made of a film having a thickness of 25 μm in which iodine is adsorbed and oriented on polyvinyl alcohol. Acrylic pressure-sensitive adhesive having a thickness of 20 μm for the purpose of protecting from scratches and dust during handling on the upper surface of the polarizer protective film layer 2 made of a triacetyl cellulose film. The surface protective film layer 4 made of a polyethylene terephthalate film having a thickness of 40 μm is bonded through the layer 3, and the other side of the polarizer layer 1 is thickened with an adhesive made of an aqueous solution containing polyvinyl alcohol and a water-soluble epoxy resin. Layer 5 made of 70 μm cycloolefin resin (hereinafter referred to as function addition) (Product name: ZEONOR, manufactured by Nippon Zeon Co., Ltd.) may be pasted, and an acrylic pressure-sensitive adhesive layer 6 having a thickness of 25 μm on one side and a polyethylene terephthalate having a thickness of 38 μm thereon. A strip-shaped polarizing plate (size: 1 m × 1 m) obtained by bonding a release film 7 made of a film was prepared.

[Example 1]
A carbon dioxide gas laser (laser light irradiation device: manufactured by Coherent, USA) having a laser wavelength of 9.4 μm is used as the above-mentioned band-shaped polarizing plate, perpendicularly to the polarizing plate absorption axis, from the surface protective film layer of the polarizing plate to immediately before the function addition layer 5 (Surface protection film layer, pressure-sensitive adhesive layer, polarizer protective film layer, polarizer layer, adhesive layer) are cut (cutting conditions: frequency 20 kHz, output: 59 W, speed: 60 m / min), Next, the function-added layer 5 and the pressure-sensitive adhesive layer 6 were cut using the fixed round blade (110φ, blade edge angle 20 °, thickness 0.3 mm, manufactured by Ebara Industries Co., Ltd.), leaving only the release film layer 7. A micrograph of the polarizing plate cut section thus obtained is shown in FIG. In addition, the cutting edge of the fixed round blade after cutting 150 polarizing plates by the two-stage cutting method using this laser (laser wavelength: 9.4 μm) and a fixed round blade was observed. There was no decline.

[Comparative Example 1]
The same strip-like polarizing plate as used in Example 1 was cut using only the fixed round blade used in Example 1, leaving only the release film layer 7 on the surface to be bonded to the substrate. The microscope picture of the cut surface of the polarizing plate cut | disconnected 10th from implementation is shown as FIG.
As apparent from FIG. 6, when the strip-shaped polarizing plate is cut using only the fixed round blade, floating is observed between the polarizer protective film layer and the surface protective film layer in the tenth cut section. Further, at the 10th time, the sharpness of the fixed round blade was poor, and as shown in FIG. 7 and FIG. 8, the cutting edge of the round blade was chipped, and further continuous use was difficult.

1 ------- Polarizer layer 2 ------- Polarizer protective film layer 2a ---- Polarizer protective film layer 3 ------- Adhesive layer 4 ---- --- Surface protective film layer 5 ------- Layer composed of a laser light low absorption rate film 6 ------- Adhesive layer 7 ------- Peeling film layer 8 ---- ----- Board

Claims

A polarizer protective film layer made of a laser light absorption film is laminated on one surface of a polarizer layer made of a polyvinyl alcohol-based resin film, and an adhesive layer on the surface opposite to the polarizer layer of the polarizer protective film A surface protective film layer made of a laser light high absorption rate film is laminated via a layer, and a layer made of a laser light low absorption rate film is formed on the other surface of the polarizer layer via an adhesive layer. A strip-shaped polarizing plate in which a release film layer made of a laser light high absorption rate film is laminated on the surface opposite to the polarizer layer of the absorptivity film layer via an adhesive layer, leaving only the release film and other polarized light A method for producing a polarizing plate comprising cutting a layer constituting a plate,
A method of cutting from a surface protective film layer to a layer immediately before a layer made of a laser light low absorption rate film with a laser, and then cutting a layer made of the laser light low absorption rate film with a cutter.
The laser light low absorption rate film is a film having an average absorption rate of laser light of 2% or less, and the laser light high absorption rate film is a film having an average absorption rate of laser light exceeding 2%. The method described.
3. The method according to claim 2, wherein the laser light low absorption rate film is a film having an average absorption rate of laser light of 1% or less.
The method according to claim 1 or 2, further comprising a polarizer protective film made of a laser light high absorptivity film between the polarizer layer and the layer made of a laser light low absorptivity film.
The method according to any one of claims 1 to 4, wherein the laser light low absorption film is a cycloolefin polymer film, a polypropylene film, or a polymethyl methacrylate film.
6. The method according to any one of claims 1 to 5, wherein the laser is a carbon dioxide laser.
A polarizing plate produced by the method according to any one of claims 1 to 6.