CN1302298C - Method for mfg. polaroid and liquid crystal display device - Google Patents

Abstract

Provided is a method for manufacturing a polarizer and a liquid crystal display device, the polarizer does not produce groove-like irregularities recorded on the surface of the protective layer due to the stretching of the polarizing film, and can obtain a clear reflection image even by reflection, while the appearance has also been improved. When the protective layer is pasted on one or both sides of the polarizer, the moisture regain of the polarizer is in the range of 5% to 30% (the moisture regain of the polarizer is measured according to the weight (A) of the polarizer before pasting and the weight of the polarizer The weight (B) of the polarizer after putting the mirror in a dryer at 120° C. for 7 hours is obtained by using the moisture regain (%) of the polarizer = [(A-B)/B]×100).

Description

Manufacturing method of polarizing plate and liquid crystal display device

technical field

This invention relates to the manufacturing method of the polarizing plate used for a liquid crystal display device (it may abbreviate as LCD hereafter), and the liquid crystal display device which has the polarizing plate obtained by this. More specifically, the present invention relates to a method for producing a polarizing plate and a liquid crystal display device, the polarizing plate does not produce groove-shaped irregularities recorded on the surface of the protective layer due to the stretching of the polarizing film, and can obtain a clear image even by reflection. Reflective images, while appearance issues have also been improved.

Background technique

LCDs are used in personal computers and the like, and tend to increase rapidly in recent years. The use of LCDs is increasing, and LCDs are also used in monitors in recent years.

After the PVA film is dyed with dichroic iodine or dyes, and then cross-linked with boric acid or borax, the polarizer is produced. In addition, uniaxial stretching is carried out in the dyeing step and the crosslinking step, but this stretching may be carried out during the steps, or may be carried out before and after the steps. After the dyeing step and the crosslinking step, usually, drying is performed using a drier, and a protective layer such as a triacetyl cellulose (TAC) film is bonded using an adhesive to produce a polarizing plate.

Polarizers used in liquid crystal display devices are required to increase both the transmittance and the degree of polarization. In order to increase both the transmittance and the degree of polarization of the polarizing plate, it is necessary to increase the stretching ratio of the PVA (polyvinyl alcohol) film which is a raw material of the polarizing plate. However, if the stretching magnification of PVA is increased, groove-like irregularities recorded in the stretching direction are likely to be formed on the surface of the polarizer, resulting in an unsightly appearance. In addition, the recorded groove-like irregularities also affect the film part such as TAC or polyethylene terephthalate (PET) attached as a protective film. When viewed after reflection, the reflected image is blurred, so there is a problem in appearance.

Contents of the invention

The present invention is proposed in order to solve the above problems, and its purpose is to provide a method of manufacturing a polarizing plate and a liquid crystal display device, the polarizing plate will not produce groove-like unevenness recorded on the surface of the protective layer due to the extension of the polarizing film , Even through reflection, a sharp reflection image can be obtained, and the appearance has also been improved.

In order to achieve the above object, the manufacturing method of the polarizer of the present invention is a method of pasting a protective layer on one or both sides of the polarizer, a transmittance of more than 35%, and a polarizer with a degree of polarization of more than 90%. The moisture regain of the polarizer at the time of pasting is 5% to 30%. The method of measuring the moisture regain of the polarizer is based on the weight of the polarizer before pasting (A) and the weight of the polarizer after putting the polarizer in a dryer at 120°C for 7 hours (B) and using the moisture regain of the polarizer (%)=[(A-B)/B]×100 is calculated.

When the moisture regain of the polarizer is less than 5%, the polarizer becomes hard, causing irregularities on the recording grooves, furthermore, there is a problem that the crosslinking agent is easily precipitated from the polarizer and appearance defects increase. In addition, when the moisture regain exceeds 30%, there is a lot of moisture, and poor adhesion is likely to occur when pasting with a protective layer such as TAC, and unevenness occurs in the polarizer surface due to decolorization of iodine through drying treatment after TAC pasting. In the above case, the ideal range of moisture regain of the polarizer is 9% to 27%.

In the above method, the surface roughness in the direction perpendicular to the extending direction of the polarizing plate is preferably 0.04 μm or less in terms of centerline average roughness. If it exceeds 0.04μm, it is easy to see unevenness. That is, unevenness is easy to stand out. Ideally, the surface roughness is expected to be below 0.01 μm, and if it is within this range, it will reach a level where the eyes cannot recognize stripes.

The above surface roughness is defined in JIS B 0601-1944.

Furthermore, in the above method, it is preferable to stick the polarizer and the protective layer together via an adhesive layer. Thereby, peeling of a polarizer and a protective layer can be prevented.

In addition, in the above method, it is preferable to dye the hydrophilic polymer film with a dyeing bath containing dichroic iodine or a dichroic dye, and to carry out crosslinking with a crosslinking bath containing a crosslinking agent, and at the same time Extend, so to make polarizers. As the hydrophilic polymer film, a polyvinyl alcohol-based film with good dyeability is preferable.

In the present invention, a reflective polarizer or a translucent reflective polarizer may be formed by laminating a reflective plate or a translucent reflective plate on the polarizer produced by the above method.

In addition, a retardation plate or a lambda plate may be laminated on the polarizing plate produced by the above method to form an elliptical or circular polarizing plate.

In addition, a viewing angle compensation film may be laminated on the polarizing plate produced by the above method to form a polarizing plate.

In addition, the luminance-enhancing film may be laminated on the polarizing plate produced by the above-mentioned method through an adhesive or an adhesive to form a polarizing plate.

Next, the liquid crystal display device of the present invention is characterized in that it has a polarizing plate produced by the above method on at least one side of the liquid crystal cell.

Detailed ways

In the manufacturing process of the polarizer of the present invention, a polarizer with a polarizing function is obtained by swelling, dyeing, stretching, crosslinking, drying, etc. of the PVA film as the raw material of the polarizer, and then, using an adhesive or adhesive Adhesive A film such as TAC or PET is pasted on the polarizer as a protective layer to obtain a polarizer.

In the manufacturing process of the polarizer, the four steps of swelling, dyeing, stretching, and crosslinking are not particularly specified in the order of the steps, and two to four of the four steps can be performed simultaneously.

In the present invention, as a method for preventing the recorded groove-shaped unevenness of the polarizer or the polarizer from occurring, the polarizer can be solved by making the polarizer and the protective layer stick when the polarizer has a moisture regain of 5% to 30%. A method of recording groove-like bumps.

In addition, it is also generally possible to temporarily roll the polarizer obtained by swelling, dyeing, stretching, crosslinking, and drying the PVA film into a cylindrical shape, and then perform humidification and other treatments on the polarizer to improve the temperature of the polarizer. A continuous production method that adjusts the humidity according to the moisture regain, and then pastes it on a protective layer such as a TAC film.

The manufacturing method of polarizers can be roughly divided into three steps, that is, the "dyeing process" in which the PVA film is dyed in a bath containing iodine or dye having dichroic properties, and the "dyeing process" in which boric acid or borax, etc. The 'crosslinking process' for crosslinking and the 'stretching process' for stretching PVA are performed in a bath of a PVA crosslinking agent. In addition, the 'stretching process' is usually carried out simultaneously with the 'dyeing process' and the 'crosslinking process' in many cases, but it can also be carried out in different processes. In addition, the dyeing process and the crosslinking process may be performed simultaneously. After the above three steps, the polarizer is dried, and a film such as a triacetyl cellulose (TAC) film or a polyethylene terephthalate (PET) film as a protective layer is pasted on one or both sides of the polarizer, Polarizers are thus produced.

As a polarizer (polarizing film), it is possible to use a suitable sequence or method of forming a suitable polyvinyl alcohol-based polymer made of a hydrophilic polymer film, such as polyvinyl alcohol or partially formaldehyde-based polyvinyl alcohol, etc. Appropriate polarizers that allow linearly polarized light to pass through appropriate treatments such as dyeing, stretching, and crosslinking of dichroic substances formed from iodine or dichroic dyes, etc., when incident natural light. In particular, a polarizer with good transmittance and polarization is preferable.

In the present invention, in order to obtain a polarizer with high transmittance and high degree of polarization, it is preferable to use a hydrophilic polymer film with a thickness of 10 to 200 μm, preferably 30 to 80 μm, etc., with a total extension ratio of 4 to 7. times, especially 5 to 6.5 times the stretch processing formed polarizer (polarizing film). When the total elongation ratio is less than 4 times, a sufficient degree of polarization cannot be obtained. When the total stretching ratio exceeds 7 times, it is difficult to manufacture a stable polarizing film because it is easily broken during stretching. In addition, when the thickness of the stretched hydrophilic polymer film is less than 10 μm, it is difficult to stretch due to stretch fracture, and when it exceeds 200 μm, it is difficult to dry during film formation, and it is easy to cause defects such as foaming, or In-plane drying unevenness tends to occur, and this uneven portion becomes uneven dyeing at the time of polarizing film production, which is not preferable. In addition, when the film is thick, swelling and dyeing unevenness tend to occur at the time of polarizing film production, which is also not good.

A suitable transparent film can be used as a protective film material to be a transparent protective layer provided on one side or both sides of the polarizer (polarizing film). As an example of the polymer, acetate-based resins such as triacetyl cellulose are generally used, but not limited thereto, polycarbonate-based resins, polynorbornene-based resins, polyethylene terephthalate resins, Transparent films such as polyester-based resins such as glycol (PET), polyethersulfone-based resins, polyamide resins, polyimide resins, polyolefin-based resins such as polyethylene, polystyrene-based resins, and acrylic-based resins , or acrylic, urethane, acrylic urethane, epoxy, and silicon-based thermosetting or UV-curing resin films.

In terms of polarization characteristics and durability, a particularly useful transparent protective film is a triacetyl cellulose film whose surface has been saponified with alkali or the like. In addition, when providing a transparent protective film on both sides of a polarizing film, you may use the transparent protective film which consists of a polymer etc. which differ from front to back.

The transparent protective film used for the protective layer may be a transparent protective film that has been treated for the purpose of hard coating, anti-reflection treatment, anti-adhesion, diffusion, and anti-glare, as long as it does not interfere with the purpose of the present invention. Hard coat treatment is performed to prevent scratches on the surface of the polarizer. For example, it can be used to attach a cured film that is excellent in hardness and lubricating properties, such as a silicon-based ultraviolet curable resin, to the surface of a transparent protective film. And so formed.

On the other hand, the antireflection treatment is performed to prevent external light from being reflected on the surface of the polarizing plate, and it can be realized by forming an antireflection film or the like conventionally used. In addition, the anti-adhesion treatment is to prevent adhesion with adjacent layers, and the anti-glare treatment is to prevent external light from being reflected on the surface of the polarizer to affect the recognition of light passing through the polarizer. For example, A polarizer can be formed by forming a fine concave-convex structure on the surface of the transparent protective film by an appropriate method such as sandblasting or embossing, or by mixing transparent fine particles.

Examples of the above-mentioned transparent fine particles include silica and alumina, titania and zirconium oxide, tin oxide and indium oxide, cadmium oxide and antimony oxide with an average particle diameter of 0.5 to 20 μm, and conductive inorganic fine particles can be used. Organic fine particles or the like made of crosslinked or uncrosslinked polymer particulates or the like may also be used. The usage amount of the transparent fine particles is generally 2-70 weight units per 100 weight units of the transparent resin, preferably 5-50 weight units.

The anti-glare layer mixed with transparent particles can be provided as the transparent protective layer itself or as a coating on the surface of the transparent protective layer. The anti-glare layer may also serve as a diffusion layer for diffusing light transmitted through the polarizing plate to widen the viewing angle (viewing angle compensation function, etc.). In addition, the above-mentioned antireflection layer, antiadhesion layer, diffusion layer, antiglare layer, etc. may be used as an optical layer formed of a sheet provided with these layers, or as a layer provided independently of the transparent protective layer.

In the present invention, there is no particular limitation on the adhesive treatment of the polarizer (polarizing film) and the transparent protective film as the protective layer, but for example, an adhesive formed of a vinyl alcohol polymer, or at least boric acid and Adhesives formed by water-soluble crosslinking agents of vinyl alcohol polymers such as borax, glutaraldehyde, melamine, and bromic acid. In particular, it is preferable to use a vinyl alcohol-based adhesive from the point of view of the best adhesiveness with a polyvinyl alcohol-based film. The adhesive layer may be formed as an applied and dried layer of an aqueous solution, but when preparing the aqueous solution, other additives or a catalyst such as an acid may be mixed as necessary.

The polarizer of the present invention can be used as an optical component formed after lamination with other opticals in practical application. The optical layer is not particularly limited, and for example, a reflective plate or a translucent reflective plate, a retardation plate (including a λ plate such as a 1/2 wavelength plate, a 1/4 wavelength plate), a viewing angle compensation film, or a luminance enhancement film can be used One or two or more optical layers, which are suitable for formation of liquid crystal display devices and the like. In particular, it is preferable to laminate a reflective plate or a semi-transparent reflective plate on the polarizer formed by the above-mentioned polarizer and protective layer of the present invention to form a reflective polarizer or a semi-transparent reflective polarizer, and then the phase Poor plate lamination forms an elliptical or circular polarizer on the polarizer formed by the polarizer of the present invention and a protective layer, and then laminates a viewing angle compensation film on the polarizer formed by the polarizer of the present invention and a protective layer to form a polarizer. sheet, or further, a brightness-enhancing film is laminated on the polarizer formed by the above-mentioned polarizer and protective layer of the present invention to form a polarizer.

Describe above-mentioned reflective plate, reflective plate is to be arranged on polarizing plate and be used for forming the part of reflective polarizer, and reflective polarizing plate is usually arranged on the back side of liquid crystal unit, can form the incident that comes from viewing side (display side). Liquid crystal display devices of the type that display light after reflection have the advantages of being able to omit a light source such as a built-in backlight, and making it easy to reduce the thickness of the liquid crystal display device.

Formation of the reflective polarizer can be carried out by an appropriate method such as a method of attaching a reflective layer made of metal or the like to one surface of the polarizer via the above-mentioned transparent protective film or the like, if necessary. Incidentally, as a specific example, if necessary, one surface of a matte-treated transparent protective film is provided with a foil or vapor-deposited film of a reflective metal such as aluminum to form a reflective layer.

In addition, examples include a reflective polarizer having a reflective layer reflecting the fine uneven structure on the above-mentioned transparent protective film containing fine particles on the surface and having a fine uneven structure on the surface. The reflective layer with the surface micro-concave-convex structure has the advantages of preventing the incident light from being diffused due to random reflection, resulting in poor directivity and dazzling appearance, and suppressing unevenness of light and shade. The formation of the micro-concave-convex structure reflective layer reflecting the micro-concave-convex structure on the surface of the transparent protective film can be carried out by directly attaching the metal to the surface, for example, by vacuum evaporation, ion plating, sputtering or other appropriate methods such as evaporation or electroplating. On the surface of a transparent protective film, etc. to carry out.

In addition, the reflector may be used as a reflector formed by providing a reflective layer on an appropriate film based on the transparent protective film instead of being directly attached to the transparent protective film of the polarizer. Since the reflective layer of the reflective plate is usually made of metal, it is best to use a thin film for the reflective surface from the point of view of preventing the decrease in reflectance due to oxidation and maintaining the initial reflectance for a long time and from the point of avoiding additional protective layers. Or the form of use covered with polarizers, etc.

In addition, the translucent polarizing plate can be obtained by using the reflective layer as a translucent reflective layer such as a half mirror which both reflects light and transmits light in the above case. The translucent polarizer is usually arranged on the back side of the liquid crystal cell, and the following types of liquid crystal display devices can be formed. When the liquid crystal display device is used in a relatively bright environment, it can be viewed from the viewing side (display side). Image display is performed after reflecting the incident light. In a relatively dark environment, the image is displayed using a built-in light source such as a background light built into the rear side of the translucent polarizer. That is, the translucent polarizer can save the energy used by light sources such as background light in a bright environment, and it is a good choice for the formation of this type of liquid crystal display device that can also use a built-in light source in a relatively dark environment. very useful.

Next, an elliptical or circular polarizing plate obtained by laminating a retardation plate on the polarizing plate formed of the aforementioned polarizer and protective layer of the present invention will be described.

When changing linearly polarized light into elliptical or circularly polarized light, changing elliptical or circularly polarized light into linearly polarized light, or changing the polarization direction of linearly polarized light, use a retardation plate, etc. A retardation plate for elliptical or circular polarized light or for converting elliptical or circular polarized light into linearly polarized light uses a so-called 1/4 wavelength plate (also referred to as a λ/4 plate). A 1/2 wavelength plate (also referred to as a λ/2 plate) is generally used in the case of changing the polarization direction of linearly polarized light.

The elliptically polarizing plate compensates for the coloring (blue or yellow) caused by the birefringence of the liquid crystal layer of the STN type liquid crystal display device, and can be effectively used for monochrome display without the above-mentioned coloring. Furthermore, it is preferable to control the three-dimensional refractive index to compensate (prevent) coloring that occurs when the screen of a liquid crystal display device is viewed from an oblique direction. A circular polarizing plate is effectively used, for example, to adjust the color tone of an image in a reflective liquid crystal display device when displaying a color image, and also has a function of preventing reflection.

Incidentally, as specific examples of the aforementioned phase difference plate, there may be mentioned pairs made of polycarbonate and polyvinyl alcohol, polystyrene and polymethyl methacrylate, polypropylene and other polyolefins, polyaryl and poly A birefringent film or an alignment film of a liquid crystal polymer formed by stretching a film made of an appropriate polymer such as an amide, or an alignment layer of a liquid crystal polymer supported by a film, or the like. In addition, as an obliquely oriented film, for example, a heat-shrinkable film and a polymer film are bonded together, and the polymer film is formed by stretching and/or shrinking under the action of the contraction force by heating. films, or films that obliquely align liquid crystal polymers, etc.

Next, a polarizing plate obtained by laminating a viewing angle compensating film on the polarizing plate comprising the aforementioned polarizer and protective layer of the present invention will be described.

The viewing angle compensation film is a film for widening the viewing angle so that a relatively clear image can be seen even when the screen is viewed obliquely rather than perpendicularly to the screen of the liquid crystal display device.

As such a viewing angle compensation film, a film obtained by coating a discotic liquid crystal on triacetyl cellulose or the like, or a retardation film can be used. A general retardation film uses a polymer film having multi-refraction extending on one axis in the planar direction, whereas a retardation film used as a viewing angle compensation film uses a polymer film having polyrefringence extending on two axes in the planar direction. A polyrefractive polymer film, or a two-direction stretched film such as an obliquely oriented polymer film having a controlled refractive index in the thickness direction that extends in one axis in the planar direction and also in the thickness direction, or the like is used. As the oblique orientation film, as mentioned above, for example, a heat-shrinkable film and a polymer film are bonded together, and the polymer film is stretched and/or shrunk under the action of the shrinkage force by heating. and formed thin films, or obliquely oriented liquid crystal polymer films, etc. As the raw material polymer of the phase difference plate, the same materials as those described above for the phase difference plate can be used.

A polarizing plate obtained by adhering a luminance-enhancing film to a polarizing plate composed of the above-mentioned polarizer and a protective layer of the present invention is usually used on the back side of a liquid crystal cell. The luminance-enhancing film shows that when natural light enters, it reflects linearly polarized light with a predetermined polarization axis or circularly polarized light with a predetermined direction by using background light such as a liquid crystal display device or reflection from the back, and transmits other light. The characteristic is that the polarizer that laminates the luminance-enhancing film on the polarizer formed by the above-mentioned polarizer and protective layer allows light from a light source such as background light to enter to obtain transmitted light in a specified polarization state. At the same time, the above-mentioned specified Light outside its polarization state is not transmitted but reflected. The light reflected on the surface of the luminance-enhancing film is reversed by a reflective layer provided on the rear side thereof and then incident on the luminance-enhancing plate, so that part or all of it is transmitted as light in a predetermined polarization state, thereby In order to increase the amount of light transmitted through the luminance-enhancing film, at the same time, the polarized light that is difficult to absorb is provided to the polarizer to increase the amount of light that can be used for liquid crystal image display, thereby improving the luminance. That is, when the luminance enhancement film is not used, when light is incident through the polarizer from the back side of the liquid crystal cell with background light, etc., the light having a polarization direction inconsistent with the polarization axis of the polarizer is almost completely absorbed by the polarizer, thereby Does not pass through polarizers. That is, although it varies depending on the characteristics of the polarizer used, about 50% of the light is absorbed by the polarizer, correspondingly reducing the amount of light available for liquid crystal images, etc., and darkening the image. The luminance-enhancing film prevents the light with the polarization direction that the polarizer can absorb from entering the polarizer, but is reflected by the luminance-enhancing film. On the board, repeat the above process, the luminance enhancement film changes the polarization direction of the light that is reflected and reversed between the polarizer and the luminance enhancement film, and the polarized light that passes through the polarizer passes through and then supplies polarization. Because of the mirror, light such as background light can be effectively used for image display of the liquid crystal display device, and the screen can be brightened.

As the above-mentioned luminance enhancement film, for example, a multi-layered laminate of a dielectric multilayer film and a film with different refractive index anisotropy, which has a function of transmitting linearly polarized light with a predetermined polarization axis and reflecting other light can be used. characteristic film (3M's 'D-BEF', etc.), or a film formed by laying a cholesteric liquid crystal layer, especially an oriented film or an oriented layer of a cholesteric liquid crystal polymer on a film base material (Nitto Denko Suitable films such as "PCF350" manufactured by the company and "Transmax" manufactured by Merck) have the property of reflecting left-handed or right-handed circularly polarized light and transmitting other light.

Therefore, in the above-mentioned type of luminance-enhancing film that transmits linearly polarized light with a predetermined polarization axis, by aligning the transmitted light with the polarization axis and directly incident on the polarizer, the absorption loss caused by the polarizer can be suppressed and the transmittance can be improved. light efficiency. On the other hand, in a luminance-enhancing film that transmits circularly polarized light like a cholesteric liquid crystal layer, it is possible to directly incident on a polarizer, but it is preferable to make the transmitted light Circularly polarized light becomes linearly polarized light after passing through the retardation plate and then enters the polarizer. As the retardation plate, circularly polarized light can be converted into linearly polarized light by using a 1/4 wavelength plate.

The phase difference plate that functions as a 1/4 wavelength plate in a wide wavelength range such as visible light can be obtained by combining a phase difference layer that functions as a 1/4 wavelength plate for monochromatic light such as light with a wavelength of 550 nm, and a phase difference layer having other phase difference characteristics. The retardation layer, for example, the retardation layer functioning as a 1/2 wavelength plate is overlapped. Therefore, the retardation film disposed between the polarizing plate and the brightness enhancement film may be a retardation film formed of one or more retardation layers.

In addition, for the cholesteric liquid crystal layer, by combining layers with different reflection wavelengths to form a configuration structure in which two or more layers overlap, a polarizing plate that reflects circularly polarized light in a wide wavelength range such as visible light can be obtained. A wide wavelength range of transmitted circularly polarized light is obtained.

In addition, the polarizing plate of the present invention can also be formed by laminating the polarizing plate and an optical laminate of two or more layers like the above-mentioned polarizing light separation type polarizing plate. Therefore, a reflective elliptically polarizing plate, a semi-transmitting elliptically polarizing plate, or the like formed by combining a retardation film with the aforementioned reflective polarizing plate or semi-transmitting polarizing plate may also be used. The optical member after the optical lamination of 2 or more layers is formed by sequential individual lamination in the manufacturing process of the liquid crystal display device etc. It is convenient and can improve the manufacturing efficiency of liquid crystal display devices and the like. In addition, appropriate bonding means such as an adhesive layer can be used at the time of lamination.

In the polarizing plate or the optical member of the present invention, an adhesive layer for bonding to other members such as a liquid crystal cell may be provided. The adhesive layer can be formed of an acrylic-based appropriate adhesive conventionally used. Among them, from the prevention of foaming and peeling caused by moisture absorption, the reduction of optical characteristics and the bending of liquid crystal cells caused by thermal expansion differences, etc., and therefore, it is easy to form a high-quality and durable liquid crystal display device. , preferably an adhesive layer with low moisture absorption and good heat resistance. In addition, it may be an adhesive layer or the like that contains fine particles and has light diffusion properties. If necessary, an adhesive layer may be provided on a necessary surface. For example, for the protective layer of a polarizer formed of the polarizer and protective layer of the present invention, an adhesive layer may be provided on one or both surfaces of the protective layer if necessary.

When the adhesive layer provided on the polarizing plate or the optical member is exposed from the surface, it is preferable to use a separator as a temporary cover in order to prevent contamination of the adhesive layer before use. The separator can be formed by, if necessary, providing a release film made of a suitable release agent such as silicon-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide on an appropriate sheet such as the above-mentioned transparent protective film.

In addition, each layer such as the polarizing film and the transparent protective film, the optical layer, and the adhesive layer forming the above-mentioned polarizer or optical member can also be formed by using, for example, a salicylate-based compound, a benzophenone-based compound, a benzotriazole UV absorbers such as cyanoacrylate compounds, nickel complex salt compounds, etc. are treated to make them have ultraviolet absorbing energy.

The polarizing plate of the present invention can be suitably used for formation of various devices such as liquid crystal display devices. The liquid crystal display device may have a conventionally suitable structure such as a transmissive type, a reflective type, or a transmissive and reflective type in which the polarizing plate of the present invention is arranged on one or both sides of a liquid crystal cell. Therefore, the liquid crystal cell forming the liquid crystal display device is arbitrary, and may be a liquid crystal cell of an active matrix drive type represented by a thin film transistor type or a simple liquid crystal cell represented by a twisted nematic type or a super twisted nematic type. A suitable type of liquid crystal cell such as a matrix-driven liquid crystal cell.

In addition, when polarizing plates or optical members are provided on both sides of the liquid crystal cell, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, one or more layers of prism array plates or lens array plates, light diffusion plates, or appropriate members such as backlights can be arranged at appropriate positions.

The present invention will now be described in more detail using the following Examples and Comparative Examples.

(Example 1)

Using a PVA film made by Clare (9X75RS, overlapping degree 2400, thickness 75μm), after stretching 3 times in the first bath (aqueous solution containing iodine and potassium iodide, temperature 30°C), in the second bath (containing boric acid and potassium iodide) aqueous solution at a temperature of 55°C) at a total stretching ratio of 6 times to obtain a polarizer. Then, use a dryer and a humidifier to adjust the temperature, humidity, air volume and time, and adjust the moisture regain of the polarizer to 6%, and then use a PVA-based adhesive to paste TAC (triacetyl cellulose) film on the polarizer. The two sides of the polarizer are produced.

(Example 2)

Using a PVA film (9X75RS) made by Clare, stretched 3 times in the first bath (aqueous solution containing iodine and potassium iodide, temperature 30°C), and then in the second bath (aqueous solution containing boric acid and potassium iodide, temperature 55°C) Stretching was carried out at a total stretching magnification of 6 times to obtain a polarizer. Then, use a dryer and a humidifier to adjust the temperature, humidity, air volume and time, and adjust the moisture regain of the polarizer to 15%, and then use a PVA-based adhesive to paste TAC (triacetyl cellulose) film on the polarizer. The two sides of the polarizer are produced.

(Example 3)

Using a PVA film (9X75RS) made by Clare, stretched 3 times in the first bath (aqueous solution containing iodine and potassium iodide, temperature 30°C), and then in the second bath (aqueous solution containing boric acid and potassium iodide, temperature 55°C) Stretching was carried out at a total stretching magnification of 6 times to obtain a polarizer. Then, use a dryer and a heating machine to adjust the temperature, humidity, air volume and time, adjust the moisture regain of the polarizer to 26%, and use a PVA-based adhesive to paste the TAC (triacetyl cellulose) film on the polarizer. Both sides of the mirror, thus creating a polarizer.

(comparative example 1)

Using a PVA film (9X75RS) made by Clare, stretched 3 times in the first bath (aqueous solution containing iodine and potassium iodide, temperature 30°C), and then in the second bath (aqueous solution containing boric acid and potassium iodide, temperature 55°C) Stretching was carried out at a total stretching magnification of 6 times to obtain a polarizer. Then, use a dryer and a humidifier to adjust the temperature, humidity, air volume, and time, and adjust the moisture regain of the polarizer to 4%. Then, use a PVA-based adhesive to paste TAC (triacetyl cellulose) film on the polarizer. The two sides of the polarizer are produced.

(comparative example 2)

Using a PVA film (9X75RS) made by Clare, stretched 3 times in the first bath (aqueous solution containing iodine and potassium iodide, temperature 30°C), and then in the second bath (aqueous solution containing boric acid and potassium iodide, temperature 55°C) Stretching was carried out at a total stretching magnification of 6 times to obtain a polarizer. Then, use a dryer and a humidifier to adjust the temperature, humidity, air volume and time, and adjust the moisture regain of the polarizer to 35%, and then use a PVA-based adhesive to paste TAC (triacetyl cellulose) film on the polarizer. The two sides of the polarizer are produced. However, since the moisture regain was 35% and the water content was high, unevenness occurred in the plane of the polarizing plate due to the drying process at the time of bonding with TAC.

The polarizing plates obtained in Examples 1 to 3 and Comparative Examples 1 to 2 above were evaluated, and the transmittance and polarization degree of a single substance were measured as optical characteristics. The centerline average roughness (Ra) and the unevenness average spacing (Sm) where streaks were formed were measured using a surface roughness profile measuring machine (manufactured by Tokyo Seiki Co., Ltd., surface roughness profile measuring machine: Surfcom 470A). Also, use visual inspection to identify streaks. The results are shown in Table 1.

Table 1 Moisture regain of polarizer (%) Polarizer Visual judgment Transmittance(%) Polarization (%) Determination of surface roughness Ra(μm) Sm(mm) Comparative Example 1 Embodiment 1 Embodiment 2 Embodiment 3 Comparative Example 2 46152635 43.843.843.843.843.8 99.9599.9599.9499.9599.90 Below 0.080.030.01 Below 0.01 Below 0.01 0.751.81 can't be measured can't be measured can't be measured There are obvious stripes The stripes are not obvious No stripes No stripes No stripes

As can be seen from Table 1, the polarizing plate of the present invention (Examples 2-3) has a low centerline average roughness (Ra) of surface roughness, and the average interval (Sm) of concavities and convexities cannot be measured, and no streaks are judged by visual inspection. In the polarizing plate of Example 1, the streaks were not conspicuous by visual inspection, and there was no practical problem.

In contrast, the polarizing plate of Comparative Example 1 had a low centerline average roughness (Ra) of surface roughness, a large average interval (Sm) of unevenness, and streaks by visual inspection because the humidity condition was outside the range of the present invention. . In the polarizing plate of Comparative Example 2, although the center line average roughness (Ra) of the surface roughness and the average interval (Sm) of concavo-convexity (Sm) were good, the degree of polarization of the optical characteristics was poor, and further, unevenness was observed in the plane. The appearance is not very good.

As explained above, in the manufacturing method of the polarizer of the present invention, when the protective layer is pasted on one side or both sides of the polarizer, the moisture regain of the above-mentioned polarizer is 5% to 30%, thus, a kind of polarizer can be provided. The production method of the sheet and the liquid crystal display device do not cause groove-shaped unevenness recorded on the surface of the protective layer due to the stretching of the polarizing film, and even if it is reflected and viewed, a clear reflected image can be seen, and the appearance has also been improved. improve. In addition, according to the manufacturing method of the present invention, a polarizer having a transmittance of 35% or more and a degree of polarization of 90% or more can be provided.

Claims (11)

1. the manufacture method of a polaroid, it is to paste protective seam and make the method for polaroid at polariscopic one or both sides, wherein, the polariscopic regain when pasting with protective seam is 15%～30%.

2. according to the manufacture method of the polaroid of claim 1 record, wherein, the surfaceness of the direction vertical with the outrigger shaft direction of polaroid is calculated below 0.04 μ m according to center line average roughness.

3. according to the manufacture method of the polaroid of claim 1 record, wherein, polariscope and protective seam are pasted together through adhesive linkage.

4. according to the manufacture method of the polaroid of claim 1 record, wherein, the hydrophilic macromolecule film is dyeed, carry out crosslinked with the crosslinked bath that comprises crosslinking chemical with comprising dye bath with dichromatic iodine or dichroic dye, extend simultaneously, make polariscope thus.

5. according to the manufacture method of the polaroid of claim 4 record, wherein, the hydrophilic macromolecule film is a polyvinyl alcohol film.

6. according to the manufacture method of the polaroid of claim 1 record, wherein, further lamination reflecting plate and form reflection type polarizer.

7. according to the manufacture method of the polaroid of claim 1 record, wherein, further lamination semi-penetration plate and form semi-penetration type polaroid.

8. according to the manufacture method of the polaroid of claim 1 record, wherein, further lamination polarizer or λ plate and form ellipse or circular polarizing disk.

9. according to the manufacture method of the polaroid of claim 1 record, wherein, further lamination viewing angle compensation film and form polaroid.

10. according to the manufacture method of the polaroid of claim l record, wherein, further come the lamination briliancy to promote film and form polaroid by cement or bonding agent.

11. a liquid crystal indicator wherein, has polaroid at least one side of liquid crystal cells, this polaroid is to be to form on 15%～30% the polariscopic one or both sides by protective seam being sticked on regain when pasting with protective seam.