JP2010224400A - Ke polarizer, manufacturing method thereof, analyzer, and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a KE polarizer for use in the preceding stage of an analyzer provided with two or more polarizing plates, an analyzer for use in the KE polarizer, and a projector including the analyzer. <P>SOLUTION: The KE polarizer having a cross transmittance (Tc) of 45 to 55% or 61 to 71% is obtained through a step of dehydrating a polymer film with an acid having a pH 3 or above. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a KE polarizer having a cross transmittance of 45 to 55% or 61 to 71%, a manufacturing method thereof, an analyzer using the KE polarizer, and a projector including the analyzer.

  A projector is a device that enlarges and projects an image modulated by a light modulation device (liquid crystal panel) onto a screen using a projection optical system, and an analyzer that absorbs high-density light (a polarizing plate on the light output side of the liquid crystal panel). Is provided. As an analyzer used for such a projector, Patent Document 1 discloses an analyzer using two or more polarizing plates. By using two or more polarizing plates, the amount of heat generated by each polarizing plate and deterioration due to light energy are reduced. As a result, the durability of each polarizing plate is improved and high output can be achieved. It is described that there is an effect.

When two analyzers are used, the optimal front stage (light incident side) polarizing plate has a cross transmittance (Tc) of about 50%. By using such a polarizing plate in the previous stage, heat can be distributed almost equally between the two elements.
However, since the polarizing plate having a high Tc (low polarization degree) has few dichroic factors, the characteristic change when the bond is broken by light or the like is large. For this reason, in conventional dye-based polarizing plates that are sensitive to light, heat, etc., it is difficult to set Tc high because the equal distribution of heat quantity between the two elements is quickly lost due to changes over time.

On the other hand, among polarizers, KE type polarizers are known to have excellent polarizer stability under severe environmental conditions such as high temperature and high humidity.
Conventionally, a KE-type polarizer having a Tc of 0.03% is produced by, for example, heat-dehydrating a stretched polyvinyl alcohol film in the presence of an acid catalyst such as hydrochloric acid, and then treating with boric acid ( Patent Document 2).

Japanese Patent Laid-Open No. 10-133196 US Pat. No. 5,666,223

  The present inventors have devised the use of a KE type polarizer having excellent polarizer stability for two or more polarizing plates used in an analyzer. However, in order to produce a KE type polarizer having a low polarization degree with a Tc of about 50% or about 66%, it is necessary to precisely control the conditions for the heat dehydration reaction and boric acid treatment of the polyvinyl alcohol film, Unlike the case of producing a conventional KE polarizer having a Tc of about 0.03%, there are many difficult aspects.

  Therefore, the present invention provides a KE-type polarizer used in the front stage (incident side) of an analyzer including two or more polarizing plates, a method for manufacturing the same, an analyzer using the KE-type polarizer, and a projector including the analyzer. It is an issue to provide.

  In order to solve the above-mentioned problems, the present inventors diligently studied a method for producing a KE polarizer having a cross transmittance (Tc) of 45 to 55% or 61 to 71%. As a result, when the dehydration treatment is performed using an acid having a pH of 3 or more and the boronation treatment is performed at a temperature of 85 to 95 ° C. using a boric acid aqueous solution having a concentration of 10 to 20%, the target KE polarizer is efficiently obtained. The inventors have found that it can be manufactured, and have completed the present invention.

Thus, according to the first aspect of the present invention, there is provided a KE polarizer characterized in that the cross transmittance (Tc) is 45 to 55% or 61 to 71%.
The KE polarizer of the present invention can be suitably used as an analyzer polarizing plate comprising two or three polarizing plates.

According to a second aspect of the present invention, there is provided a method for producing the KE polarizer of the present invention, comprising a step of dehydrating a polymer film containing a vinyl alcohol polymer with an acid having a pH of 3 or more. A method for producing a KE polarizer is provided.
In the method for producing a KE polarizer of the present invention, it is preferable to use phosphoric acid or a water or alcohol solution of phosphoric acid as the acid having a pH of 3 or more.
The method for producing a KE-type polarizer of the present invention includes a boronation treatment step in which the polymer film obtained by the dehydration step is brought into contact with an aqueous boric acid solution having a concentration of 10 to 20% at a temperature of 85 to 95 ° C. It is preferable.
According to the method for producing a KE polarizer of the present invention, the KE polarizer of the present invention can be efficiently produced.

According to a third aspect of the present invention, there is provided an analyzer having at least one KE type polarizer of the present invention and a KE type polarizer having a cross transmittance (Tc) of 0 to 0.1%. The
The analyzer of the present invention can be suitably used for a projector.

According to a fourth aspect of the present invention, there is provided a projector including the analyzer according to the present invention.
In the projector of the present invention, by appropriately sharing the amount of light absorbed by each polarizer of the analyzer, the durability of the analyzer can be improved and high brightness can be achieved.

It is sectional structure sectional drawing of the analyzer of this invention. It is a conceptual diagram of the projector of this invention. FIG. 2 is a cross-sectional view of a layer configuration of a light modulation device provided in the projector of the present invention.

  Hereinafter, the present invention will be described in detail by dividing it into 1) a KE type polarizer, 2) a method for manufacturing a KE type polarizer, 3) an analyzer, and 4) a projector.

1) KE type polarizer The KE type polarizer of the present invention has a cross transmittance (Tc) of 45 to 55% or 61 to 71%.
Here, the cross transmittance (Tc) is the amount of light that is incident on the measurement object so that the linearly polarized light (Pa) obtained by passing the light from the light source through the polarizer is perpendicular to the transmission axis of the measurement object and transmitted through the measurement object. By measuring (Pt),

It can ask for.
A KE polarizer is a synthetic dichroic planar polarizer based on a molecularly oriented vinyl alcohol polymer (PVA) sheet or film having a stable concentration of light absorbing chromophore. The dichroism of a KE polarizer is derived from the light absorption of the matrix, not the light absorption of the dye additive, dyed or suspended crystalline material. Therefore, the KE polarizer can have both good polarization efficiency and good heat resistance and moisture resistance.

  The polyvinylene chromophore of the KE polarizer is stable to chemicals. The reason is that the chromophore is inherent in the polymer molecule. This chromophore is thermally stable and is resistant to a wide variety of solvents and chemicals even when incorporated into a cross-linked vinyl alcohol polymer matrix.

KE polarizers also have improved polarizer stability under harsh environmental conditions such as high temperatures and high humidity. Therefore, the KE polarizer can be used in applications that require high performance under severe environmental conditions such as high temperature, high humidity, long time, and high luminous flux (for example, light intensity). Under such environmental conditions, the stability of conventional H-type polarizers and iodine-based polarizers is greatly reduced, which limits the practicality in applications such as projection systems.
Because KE polarizers have inherent chemical stability, a wide variety of adhesive formulations such as pressure sensitive adhesives can also be applied directly.

As will be described later, the KE polarizer of the present invention can be suitably used as a polarizing plate on the front stage (incident side) of an analyzer constituted by two or three KE polarizers.
By configuring the analyzer with two or three KE-type polarizers, heat can be distributed, so that the amount of heat generated by each polarizing plate and deterioration due to light energy are reduced. Durability is further improved and higher output can be expected.

  The thickness of the KE polarizer may be appropriately determined according to the application, but is usually 10 to 50 μm, preferably 20 to 40 μm.

  The KE type polarizer of the present invention can be manufactured in the same manner as the conventional method for manufacturing a KE type polarizer having a Tc of about 0.03%. Is preferred.

2) Manufacturing method of KE type polarizer The manufacturing method of the KE type polarizer of the present invention includes a polymer film containing a vinyl alcohol polymer (including a polymer sheet. The same applies hereinafter. Hereinafter, it is referred to as "polyvinyl alcohol film". Is a method for producing a KE-type polarizer of the present invention, which comprises a step of dehydrating a polyvinyl alcohol film with an acid having a pH of 3 or more.

  Specifically, the polymer film is stretched in one direction to align the PVA matrix, and the polyvinyl alcohol film is heated in the presence of an acid having a pH of 3 or more to form a conjugated polyvinylene block. be able to.

  In addition, as described in US Pat. No. 5,666,223, it is preferable to perform a boric acid treatment after dehydrating the polymer film.

Specifically, the KE type polarizer of the present invention can be produced as follows.
First, a polyvinyl alcohol film is uniaxially stretched and dehydrated to realize polarization characteristics.
The polyvinyl alcohol film is a film made of a resin containing a vinyl alcohol polymer.

  Specific examples of vinyl alcohol-based polymers include linear 1,3-polyhydroxylated polymers or copolymers or derivatives thereof that can be dehydrated into linear conjugated vinyl polymers.

  Useful vinyl alcohol-based polymers include polymers and copolymers of units having the formula:

Here, R ¹ is a hydrogen atom, a C1-C8 alkyl group, or an aryl group, and R ² is a hydrogen atom or a hydrolyzable functional group such as a C1-C8 acyl group, preferably R ^1. And R ² is a hydrogen atom.

  Comonomers that can be polymerized with vinyl alcohol monomers to form vinyl alcohol copolymers include olefins such as ethylene, propylene, and butylene; (meth) acrylates such as acrylate and methyl methacrylate; vinyl such as vinyl acetate Esters; aromatic vinyl compounds such as styrene and α-methylstyrene; and the like.

  When the vinyl alcohol-based polymer is a vinyl alcohol copolymer, the amount of comonomer used is less than 30 mol%, preferably less than 10 mol%, based on the entire monomer. When the amount of comonomer used is increased, formation of a conjugated vinylene block (poly (acetylene) block) is delayed, which may adversely affect the performance of the polarizer.

  Among these, the vinyl alcohol polymer is preferably a vinyl alcohol homopolymer or vinyl alcohol copolymer, and more preferably a vinyl alcohol homopolymer.

  Moreover, polyvinyl acetal, polyvinyl ketal, and polyvinyl ester can also be used as a vinyl alcohol-type polymer.

In addition, melt processable vinyl alcohol polymers can also be used in the present invention.
Melt processable vinyl alcohol polymers are plasticized to improve their thermal stability and allow them to be extruded or melt processed.

  The plasticizer can be added externally or can be part of a vinyl alcohol-based polymer chain, in other words, the plasticizer is polymerized or grafted onto the vinyl alcohol polymer backbone.

  Vinyl alcohol-type polymers that can be plasticized externally include “Mobiol” 26-88 and “Mobiol” available from Clariant Corporation, Charlotte, NC. "A commercially available product such as a 23-88 vinyl alcohol polymer resin.

  As a plasticizer useful when plasticizing a vinyl alcohol polymer from the outside, a high-boiling water-soluble organic compound having a hydroxyl group can be mentioned. Examples of such compounds include water, glycerol, polyethylene glycols such as triethylene glycol and diethylene glycol, trimethylolpropane, and combinations thereof.

The amount of plasticizer added varies with the molecular weight of the vinyl alcohol polymer.
Generally, the plasticizer is added in an amount of about 5% to about 30% by weight, preferably about 7% to about 25% by weight, based on the vinyl alcohol-based polymer.

  Materials available from Celanese under the Vinex trademark are certain thermoplastic water-soluble polyvinyl alcohol resins. For example, the “Vinex” 2000 series including “Vinex” 2034 and “Vinex” 2025 are internally plasticized cold water soluble and hot water soluble polyvinyl alcohol copolymer resins. Such internally plasticized vinyl alcohol copolymers are described in US Pat. No. 4,948,857. Such copolymers have the general formula:

Here, R ³ is a hydrogen atom or a methyl group,
R ⁴ is a C6-C18 acyl group,
y is 0-30 mol%,
z is 0.5 to 8 mol%,
x is 70 to 99.5 mol%.

  These copolymers maintain the strength properties of vinyl alcohol-based polymers and also exhibit increased flexibility. The acrylate monomer represented by the above formula gives the copolymer its internal plasticizing effect.

  First, uniaxial stretching of the polyvinyl alcohol-based film can be performed using a suitable stretching device or other similar mechanism or system, and the polyvinyl alcohol-based film is about 3.5 times the original length of the film. The film can be stretched from double to about 7.5 times or more.

  Stretching can occur at various stages throughout the film manufacturing process. Here, the stretching performed before the dehydration treatment is referred to as a first stretching step. Stretching performed simultaneously with the dehydration process is referred to as a second stretching process, and stretching performed after the dehydration process, for example, before or after the boric acid treatment process is referred to as a third stretching process.

  The dehydration treatment is usually performed by first exposing the polyvinyl alcohol film to an acid having a pH of 3 or higher, and then heating the exposed film. Specifically, the polyvinyl alcohol film can be immersed in deionized water for about 1 second to about 5 minutes, and then immersed in an acid having a pH of 3 or more for a desired time.

  In addition, the polyvinyl alcohol film can be exposed to the dehydration catalyst by different methods. For example, the film can be dipped or immersed in an aqueous dehydration catalyst with sufficient residence time to diffuse the catalyst into the film.

  The acid used in the dehydration treatment is conjugated vinylene units by removing hydrogen and oxygen atoms from the hydroxylated portion of the linear polymer in the presence of heat or other suitable treatment conditions at a pH of 3 or higher. Any acid that can leave a mark can be used.

Specific examples include hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, and sulfuric acid. These acids may be diluted with water or alcohol such as methanol.
Among these, the use of a weak acid that easily adjusts the pH to 3 or more is preferable, and the use of phosphoric acid or a water or alcohol solution of phosphoric acid is particularly preferable.

  By using a weak acid, particularly phosphoric acid, the concentration of the acid catalyst can be easily and precisely controlled by a predetermined value.

  Further, by using an acid catalyst having a pH of 3 or more, the amount of conjugated polyvinylene block produced can be precisely controlled, and a polarizer having a cross transmittance (Tc) of 45 to 55% or 61 to 71% can be obtained. It can be simply and efficiently produced.

For example, in the case of using hydrochloric acid, when manufacturing a conventional polarizing plate having a Tc of about 0.03%, hydrochloric acid having a concentration of about 0.013 mol / l may be used. However, when manufacturing a polarizing plate having a Tc of about 50% according to the present invention, hydrochloric acid having a concentration of about 1/5 or less and about 0.0019 mol / l must be used, and the concentration control is very difficult. Also, the concentration after preparation tends to be unstable.
On the other hand, if a weak acid (such as phosphoric acid) is used, a polarizing plate having the same characteristics can be obtained at a higher concentration. For example, when the concentration of phosphoric acid is about 6 to 7 times that of hydrochloric acid, which is a strong acid, a polarizing plate having similar characteristics can be obtained. Therefore, since a higher density than the conventional one can be set as the target value, the density control becomes easy.

  After exposing the polyvinyl alcohol-based film to the dehydration catalyst, the polyvinyl alcohol-based film and the adsorption catalyst can be heated, thereby converting a portion of the oriented film into polyvinylene, the desired dehydration product. The film can be heated by conduction heating, convection heating, radiation heating, or a combination thereof.

  For example, the film and catalyst can be passed through a heated oven at a temperature range of about 88 ° C. to about 205 ° C. for about a few seconds to about 10 minutes. In another method, the film and catalyst can be exposed to microwave radiation heating, laser heating, or radiant infrared heating.

  In the dehydration step, a part of the vinyl alcohol polymer in the polyvinyl alcohol film is converted into a polarized molecule of a block copolymer of poly (vinylene-co-vinyl alcohol).

  The effect of the dehydration treatment is to form a conjugated polyvinylene block from the polyvinyl alcohol block. By orienting the PVA matrix in one direction, the transition moment of the conjugated polyvinylene block is also oriented, making the material visibly dichroic. The conjugated polyvinylene block can be referred to as a dichroic chromophore.

During the dehydration process, the polymer film can be subjected to a second stretching step. In other words, the film can be stretched a second time during the dehydration process.
Like the first stretching step, the second stretching step is performed at a temperature above the glass transition temperature of the polymeric material and can be accomplished by providing a heat generating element, a fast roller, and a slow roller.

  However, in the second stretching step, in order to reduce the contrast, it is preferable to set the stretching ratio to be smaller than the stretching ratio at the time of manufacturing a normal polarizing plate with Tc≈0%. For example, if the draw ratio when producing a polarizing plate having a Tc of about 0.03% is 1.88, when producing a polarizing plate of the present invention having a Tc of about 50%, 1.5. It is preferable to set it to -1.8 times. By controlling the draw ratio in the drawing step during the dehydration process in this manner, the KE polarizer of the present invention can be more easily produced.

  It is preferable to subject the polyvinyl alcohol film to a boric acid treatment step after dehydration treatment. For example, the oriented film is treated with boric acid by exposing the converted polyvinyl alcohol film (hereinafter sometimes simply referred to as “polymer film”) to an aqueous boric acid solution. By performing a boric acid treatment step, relaxation and crosslinking are performed.

  In the present invention, the boric acid treatment preferably includes a step of bringing the polymer film into contact with an aqueous boric acid solution having a concentration of 10 to 20% at a temperature of 85 to 95 ° C.

  The boric acid treatment step can be performed using one or more baths. By using a plurality of baths and sequentially passing the baths, the boric acid treatment time can be sufficiently secured without enlarging one bath. The number of baths is preferably 2 or 3.

  In the two-bath boric acid treatment, the first bath can contain water, and the second bath can contain boron ion-contributing species. The order of the baths can be reversed, or both baths can contain various concentrations and / or mixtures of boron ion contributing species.

The concentration of boric acid and borax or other borate in the solution or solutions to which the film is exposed can be varied.
Among them, in the present invention, at least the last bath uses a boric acid aqueous solution having a concentration of 10 to 20%, which is higher than other baths, and adjusts the draw ratio and temperature to adjust the load applied to the polymer film. It is preferable to promote crosslinking by lowering. It is preferable that the third draw ratio is about 1 and the temperature is 85 to 95 ° C. and the load applied to the polymer film is lowered to bring boric acid into contact therewith.

  For example, when boric acid treatment is performed using three baths and a polarizing plate having a Tc of about 0.03% is manufactured, an aqueous boric acid solution having a concentration of 7% by weight is used for all three baths, and the temperature is 90%. Contact at ~ 94 ° C. On the other hand, when producing the polarizing plate having Tc of about 50% according to the present invention, the boric acid treatment for the first and second baths is performed in the same manner as described above, and the aqueous boric acid solution having a concentration of 15% by weight in the third bath It is preferable to make it contact at the temperature of 85-95 degreeC.

  The KE-type polarizer of the present invention has a low contrast and has more hydroxyl groups than the conventional KE-type polarizer. Therefore, if the temperature in the boric acid treatment process is high, the polymer film absorbs too much water. Too soft and easy to tear. On the other hand, when the temperature is lowered, sufficient crosslinking reaction does not occur. Therefore, it is preferable to enhance the crosslinking treatment by setting the concentration of the boric acid aqueous solution to the above value while keeping the boric acid treatment temperature slightly low in the final bath after treatment to some extent under normal conditions.

  The boric acid aqueous solution may contain borax in an amount of 0 to 7% by weight, preferably 0 to 3% by weight.

  The time for exposing the polymer film to the boric acid aqueous solution is usually 30 seconds to 30 minutes in total, preferably 1 minute to 10 minutes.

After exposure to an aqueous boric acid solution, the resulting film can be rinsed and dried. The film can be rinsed using any suitable method, such as by passing the film through a bath of deionized water or by spraying deionized water onto the film.
Examples of the method for drying the film include a method of heating the film by convection heating or radiation heating, a method of passing the film through a convection oven, and the like.

  Also, a processing agent, such as a surfactant such as Triton X100 commercially available from Union Carbide (Danbury, Conn.) Can be added to the boric acid bath to aid the process.

  If the film is not left under tension, it will shrink during the boric acid treatment process. Shrinking the film allows the film to absorb more boron-containing solution, thus providing a higher degree of cross-linking with the accompanying increased environmental stability.

  In addition, a 3rd extending | stretching process can be performed in the boric-acid treatment process of a film, or before and after that. For example, the film can be submerged, softened and / or swollen in an aqueous boric acid solution. This often results in film relaxation or shrinkage. Thereafter, the film is taken out and dried.

  The processes of wet stretching, dehydration and boric acid can be performed as a continuous integration process. Such a continuous process is simpler than the multi-step process used in the past for intrinsic polarizers, resulting in higher film yields and reduced polarizer costs.

  The polarizing film obtained as described above includes a PVA / polyvinylene block copolymer material molecular alignment film composite in which a polyvinylene block is formed by molecular dehydration of a film of polyvinyl alcohol. The molecularly oriented film of the polyvinyl alcohol / polyvinylene block copolymer material comprises a uniform distribution of polarized molecules of the polyvinyl alcohol / polyvinylene block copolymer material in which the number (n) of conjugated repeating vinylene units of the polyvinylene block of the copolymer varies. The value of n is 2 to about 25. The degree of orientation of the polarizing molecules increases with increasing values of n over the entire range.

  In the polarizing film obtained as described above, the degree of orientation of molecules related to the concentration distribution of each polyvinylene block is 5 to 50 and the photopic dichroic ratio (RD) is a polymer. Enough to feed the film.

  The photopic dichroism ratio D is a value defined by D = Az / Ay ignoring surface reflection. Here, Az and Ay are determined as follows. The sample polarizer is illuminated with a white sample beam of a dual beam spectrophotometer. The sample beam is pre-polarized using a high efficiency Glan type polarizer. The amount of light transmitted through the sample polarizer at a particular wavelength is compared to the amount of light at the same wavelength of the reference beam, and the absolute absorbance of the sample polarizer as a function of wavelength, Calculate from the ratio. Absorbance is calculated over the range 380 nm to 780 nm. Absorbance spectra are obtained for both light polarized parallel to the transmission axis of the sample polarizer and light polarized perpendicular to the transmission axis of the sample polarizer. The parallel and vertical absorbance spectra are then spectrally corrected (photopic correction) for the specific light source spectrum and the response of the human eye. The integrated area under the corrected parallel absorbance spectrum corresponds to the amount of parallel corrected light Ay absorbed in one pass through the sample polarizer, which is spectrally corrected. The integrated area under the corrected vertical absorbance spectrum corresponds to the spectrally corrected amount of light Az in the vertically polarized state absorbed in one pass through the sample polarizer.

3) Analyzer The analyzer of the present invention has at least one KE polarizer of the present invention and a KE polarizer having a cross transmittance (Tc) of 0 to 0.1%.
The analyzer is a polarizing plate on the output side of the liquid crystal display that absorbs high-density light in the projector.

  An analyzer having two polarizers on the incident light side (front stage) and the outgoing light side (rear stage) has the KE type polarizer of the present invention having a Tc of 45 to 55% in the front stage, and the Tc in the range of 0 to 0.00. A 1% polarizer is used in the subsequent stage. In addition, an analyzer having three polarizing plates in the front, middle and rear stages has a KE type polarizer of the present invention having a Tc of 61 to 71% in the front stage and a polarizer having a Tc of 45 to 55% in the next stage. In addition, a polarizer having a Tc of 0 to 0.1% is used in the subsequent stage.

  Since the analyzer is composed of two or three polarizers and the KE-type polarizer of the present invention having a Tc of 45 to 55% is used in the previous stage, heat can be equally distributed. As a result, the durability of each polarizer is further improved and high output can be expected.

Hereinafter, an example (Embodiment 1) of the analyzer of the present invention will be described.
A cross-sectional view of the analyzer 10A according to Embodiment 1 is shown in FIG.
The analyzer 10A is a polarizing member disposed on the light exit side of a projector including a light modulation device, and from the light exit side, a support layer, an adhesive layer, a KE polarizer (I), an adhesive layer, a transparent layer, and the like. The optical substrate, further, the support layer, the adhesive layer, the KE polarizer (II), the pressure-sensitive adhesive layer, and the translucent substrate are arranged in this order.
In FIG. 1, 1 is a support layer, 2 is an adhesive layer, 31 is a KE-type polarizer (I), 32 is a KE-type polarizer (II) of the present invention, 4 is an adhesive layer, and 5 is a translucent substrate. It is.

(Support layer)
The support layer 1 is not particularly limited as long as it has excellent light transmittance in the visible region.
The material constituting the support layer 1 includes acetyl cellulose resin, acrylic resin, polycarbonate resin, polyethylene terephthalate resin, polyimide resin, polyethylene naphthalate, epoxy resin, cyclic olefin resin, and cyclic olefin-ethylene copolymer. Examples thereof include transparent synthetic resins such as polymerization resins, polyvinyl butyral resins, polyethersulfone resins, polyvinyl chloride, and polystyrene.
A mixture of two or more resins may be used, and examples thereof include polyethylene / polyphenylene ether, polyvinyl chloride / styrene-acrylonitrile copolymer, polyvinyl chloride / polymethyl methacrylate, and the like.
Among these, acetylcellulose-based resins are preferable, and triacetylcellulose is particularly preferable.

  The thickness of the support layer 1 is usually 10 to 300 μm, preferably 50 to 200 μm, more preferably 60 to 150 μm.

Further, an antireflection layer (not shown) may be formed on the surface of the support layer 1 on the side where the adhesive layer 2 described later is not provided.
As a method for forming the antireflection layer, either a dry process or a wet process can be used. The dry process is a method of forming each layer by vacuum deposition, sputtering, ion plating, or the like. On the other hand, in the wet process, the coating liquid for forming each layer is applied using a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. Is a method of forming

(Adhesive layer)
As the adhesive used for forming the adhesive layer 2, either a thermosetting adhesive or an ultraviolet curable adhesive can be used. Examples of the thermosetting adhesive include polyolefin adhesives such as ethylene / anhydride copolymers, epoxy resin adhesives, urethane resin adhesives, phenol resin adhesives, and the like. Examples of the ultraviolet curable adhesive include acrylic adhesives, enethiol adhesives, and epoxy adhesives. Among these, an ultraviolet curable adhesive is preferable from the viewpoint of production efficiency.

Moreover, the adhesive agent used may contain a silane coupling agent. The silane coupling agent to be used is not particularly limited as long as it can contribute to improvement in adhesion between the support layer 1 and the KE polarizer 32.
Examples of such silane coupling agents include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3- Glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyl Trimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-amino Propyl triet Silane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, Examples thereof include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

  When the silane coupling agent is contained in the adhesive to be used, the content thereof is preferably 0.1% by weight to 10% by weight, more preferably 0.3% by weight to 7% by weight with respect to the adhesive.

(Adhesive layer)
The pressure-sensitive adhesive layer 4 can be formed, for example, by applying a pressure-sensitive adhesive composition to the surface of the KE polarizer 32 and drying it.

  It does not restrict | limit especially as an adhesive composition to be used, The well-known adhesive composition containing an acrylic polymer and a crosslinking agent is mentioned. Moreover, PSA (Pressure Sensitive Adhesive) excellent in adhesive strength, heat resistance, and moisture resistance may be included.

  The acrylic polymer is obtained by polymerizing one or more monomers selected from n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isononyl acrylate, acrylic acid, methyl methacrylate, and the like. Can be mentioned.

  As a crosslinking agent, a monomer containing a carboxyl group such as acrylic acid, methacrylic acid, maleic acid and itaconic acid which may have two functional groups; a hydroxyl group which may have two functional groups And the like; acrylamide; methacrylamide; glycidylamide; and the like.

(Translucent substrate)
The translucent substrate 5 is not particularly limited, and a conventionally known substrate can be used. For example, a substrate made of quartz glass, hard glass, crystallized glass, cubic sintered body, sapphire, crystal, white plate glass, heat resistant glass, YAG polycrystal, aluminum oxynitride, or the like can be given.

(KE type polarizer (I))
The KE polarizer (I) 31 is a polarizing plate having a cross transmittance (Tc) of 0 to 0.05%. The KE polarizer (I) can be produced by a conventionally known method. For example, a vinyl alcohol polymer film is stretched in one direction to align the PVA matrix, and the PVA type polymer film is heated in the presence of a dehydration catalyst such as hydrochloric acid to produce a conjugated polyvinylene block. (treatment) can be obtained.

(KE type polarizer (II))
The KE-type polarizer (II) 32 is a KE-type polarizer according to the present invention having a cross transmittance (Tc) of 45 to 55%, and can be manufactured by the above-described manufacturing method.

  The thicknesses of the KE type polarizers (I) 31 and (II) 32 are usually 10 to 50 μm, preferably 20 to 40 μm, respectively.

4) Projector The projector of the present invention includes the analyzer of the present invention.
Hereinafter, an example (second embodiment) of the projector of the present invention will be described.
The projector according to the second embodiment includes an illumination device that emits an illumination light beam, a light modulation device that modulates the illumination light beam from the illumination device according to image information, and a projection that projects light modulated by the light modulation device. An optical system and the analyzer of the present invention shown in Embodiment 1 are provided on the light emitting side of the light modulation device.

A conceptual diagram of the projector of the present invention is shown in FIG.
A projector 100 shown in FIG. 2 is a kind of projection type image display apparatus.
The projector 100 includes an image forming optical unit 60, an illumination device 61, and a projection optical system 40.

The image forming optical unit 60 illuminates with a color separation optical system 63 that separates the illumination light emitted from the illumination device 61 into three colors of red, green, and blue, and illumination light of each color emitted from the color separation optical system 63. And a cross dichroic prism 67 that synthesizes the modulated light of each color that has passed through the light modulation device 65.
The liquid crystal device and the analyzer in the projector according to the second embodiment correspond to the light modulation device 65 in the projector 100 shown in FIG.

  The illumination device 61 includes a light source unit 61a that emits light source light, and a uniformizing optical system 61c that converts the light source light emitted from the light source unit 61a into illumination light that is uniform and aligned in a predetermined polarization direction. The light source unit 61a includes a light source lamp 61m and a reflector 61n. The uniformizing optical system 61c includes a first lens array 61d for dividing the light source light into partial light beams, a second lens array 61e for adjusting the spread of the divided partial light beams, and the polarization directions of the partial light beams. It includes a polarization conversion device 61g that aligns and a superimposing lens 61i that superimposes and enters each partial light beam on a target illumination area.

  The color separation optical system 63 includes first and second dichroic mirrors 63a and 63b and optical path bending mirrors 63m, 63n, and 63o, and branches the system optical axis SA into three optical paths OP1 to OP3. The illumination light is separated into three light fluxes of blue light LB, green light LG, and red light LR. The relay lenses LL1 and LL2 transmit the image formed immediately before the incident-side first relay lens LL1 to the field lens 63h on the exit side almost as it is, so that light use efficiency due to light diffusion or the like is achieved. Is prevented.

  The light modulation device 65 includes three liquid crystal devices 65a, 65b, and 65c into which illumination lights LB, LG, and LR of three colors respectively enter, and passes through field lenses 63f, 63g, and 63h, and enters the liquid crystal devices 65a, 65b, and 65c. The incident color lights LB, LG, and LR are intensity-modulated in units of pixels in accordance with the drive signals.

  Each of the liquid crystal devices 65a, 65b, and 65c is an image forming element having a structure in which a liquid crystal panel is sandwiched between a pair of polarizing plates as shown in FIG.

  In FIG. 3, 1 is a support layer, 2 is an adhesive layer, 31a, 31b, and 32a are KE type polarizers, 4 is an adhesive layer, 5 is a translucent substrate, 6 is a liquid crystal panel, and 10B is a polarizing member (incident 10C is an analyzer (outgoing side).

  The polarizing member 10 </ b> B of the liquid crystal light valves 65 a, 65 b, and 65 c includes the support layer 1, the adhesive layer 2, the KE polarizer 31 a, the pressure-sensitive adhesive layer 4, and the translucent substrate 5. The analyzer 10C includes a KE type polarizer (I) 31b and a KE type polarizer (II) 32a, and has the same structure as 10A of the first embodiment.

  The cross dichroic prism 67 includes dichroic films 67a and 67b that intersect with each other, and emits image light obtained by synthesizing modulated light from the liquid crystal devices 65a, 65b, and 65c.

  As shown in FIG. 2, the projection optical system 40 projects the image light combined by the cross dichroic prism 67 on the screen with a suitable magnification and a relatively small aberration as a color image.

  According to the projector of the second embodiment, by appropriately sharing the amount of light absorbed by each polarizer of the analyzer, the durability of the analyzer can be improved and high output can be achieved.

(Modification of embodiment)
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the projector according to the second embodiment, an analyzer having the same structure as the analyzer 10C is used as an analyzer for all three liquid crystal light valves. However, the present invention is not limited to this, and one of them is used. Or two.

  As the analyzer 10A of the first embodiment and the analyzer 10C of the projector of the second embodiment, an analyzer in which KE type polarizers (I) 31, 31b and KE type polarizers (II) 32, 32a are combined is used. The present invention is not limited to this, and a three-sheet configuration in which a KE type polarizer having a cross transmittance of 61 to 71% is disposed in front of the KE type polarizer.

  In the projector of the second embodiment, the KE type polarizer is used as the polarizer disposed on the incident side of the liquid crystal panel 6. However, the present invention is not limited thereto, and an arbitrary polarizing plate can be selected. it can.

DESCRIPTION OF SYMBOLS 1 ... Support layer, 2 ... Adhesive layer, 31, 31a, 31b ... KE type polarizer (I), 32, 32a ... KE type polarizer (II), 4 ... Adhesion Agent layer, 5 ... translucent substrate, 6 ... liquid crystal panel, 10A, 10C ... analyzer, 10B ... polarizer, 60 ... image forming optical part, 61 ... illumination device 63 ... Color separation optical system, 65 ... Light modulation device, 61a ... Light source unit, 61c ... Uniformation optical system, 61d ... Lens array, 61m ... Light source lamp, 61n ..Reflector, 62e ... second lens array, 61g ... polarization converter, 61i ... superimposed lens, 63 ... separate illumination system, 63a ... first dichroic mirror, 63b ... first 2 dichroic mirrors, 63m, 63n, 63o ... mirrors for optical path bending 63h: Field lens, 65a, 65b, 65c ... Liquid crystal device, 63f, 63g, 63h ... Field lens, 67 ... Cross dichroic prism, 67a, 67b ... Dichroic film, LL1, LL2,. ..Relay lenses

Claims (6)

  A KE type polarizer having a cross transmittance (Tc) of 45 to 55% or 61 to 71%.   A method for producing the KE polarizer according to claim 1, comprising a step of dehydrating a polymer film containing a vinyl alcohol polymer with an acid having a pH of 3 or more. How to manufacture.   The method for producing a KE polarizer according to claim 2, wherein phosphoric acid or a water or alcohol solution of phosphoric acid is used as the acid having a pH of 3 or more.   The KE type according to claim 2, further comprising a boronation treatment step in which the polymer film obtained by the dehydration step is brought into contact with a boric acid aqueous solution having a concentration of 10 to 20% at a temperature of 85 to 95 ° C. A method for producing a polarizer.   An analyzer comprising at least one KE polarizer according to claim 1 and a KE polarizer having a cross transmittance (Tc) of 0 to 0.1%.   A projector comprising the analyzer according to claim 5.

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