JPH1114830A - Production of polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the disturbance in the arrangement of an optically active polymer layer by an external factor, such as contact, and to enable the forming of fine polariza tion patterns by irradiating an optically active high-polymer layer having a photosensi tive group of a photodimerization type at its side chain on a substrate with the polar ized light of UV rays and providing the surface of this layer with a layer contg. dichromatic molecules. SOLUTION: The high-polymer layer having the photosensitive group of the photodimerization type at its side chain on the substrate consisting of silica glass, hard glass, etc., is irradiated with the polarized light of the UV rays and the surface of this layer is provided with the layer contg. the dichromatic molecule. The wavelength of the polarized light of the UV rays is preferably specified to <=320 nm at this time. The photosensitive group of the photodimerization type which induces a photocyclization addition reaction of a 2+2 type by the UV rays includes, for example, photosensitive groups consisting of an arom. ring or heterocycle having aliphat. C=C double bonds, for which an unsaid. aliphat. carboxylic acid group having the arom. ring or heterocycle is adequately usable. The carboxylic acid group which is bonded to a high polymer as a side chain by an ester bond is more preferable and the example of such group includes a cinnamic acid group, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for manufacturing a polarizing plate.

[0002]

2. Description of the Related Art Polarizing elements used in liquid crystal displays, sunglasses, goggles, etc. dissolve or adsorb dichroic molecules in a polymer substance such as polyvinyl alcohol.
It is manufactured by a method in which the film is stretched in one direction to arrange dichroic molecules. It is also manufactured by a method in which dichroic molecules are adsorbed on a polymer film stretched in a uniaxial direction. However, the polarizing axis of the polarizing element obtained by these methods is fixed in one direction, and only a flat plate can be manufactured. In order to manufacture various display elements including a liquid crystal display, a polarizing element or a polarizing element having a fine pattern and exhibiting polarization in an arbitrary direction is required.

Conventionally, for this purpose, Japanese Unexamined Patent Publication No.
No. 024, a method of irradiating a layer containing a photoactive molecule and a layer containing a photoactive molecule in contact with the layer with linearly polarized light and then adsorbing dye molecules on the photoactive molecule layer has been performed.

However, in this method, the molecular movement of the photoactive molecules is not fixed because the molecular movement of the photoactive molecules is induced and arranged in one direction only by irradiating the photoactive molecule layer with linearly polarized light. Therefore, the arrangement of the photoactive molecular layer may be disturbed by an external factor such as contact.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a polarized light capable of adsorbing dye molecules without disturbing the arrangement by another means instead of the molecular motion of the photoactive molecular layer, and forming an extremely fine polarization pattern. An object is to provide an element, a polarizing plate, and a method for manufacturing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have found that C = C
By irradiating a polymer having a double bond and an aromatic or heterocyclic ring with ultraviolet polarized light, it has been newly found that the polymer is cross-linked and fixed in one direction. When a dichroic molecule layer was provided thereon, it was found that dichroic molecules were arranged anisotropically.

The present invention has been completed based on this finding. That is, the present invention provides (1) irradiating a polymer layer having a photodimerizable photosensitive group in a side chain on a substrate with ultraviolet polarized light, and then providing a layer containing dichroic molecules on the layer. (2) The photo-dimerization type photosensitive group is a photosensitive group comprising an aromatic ring or a hetero ring having an aliphatic C = C double bond. The present invention relates to a method for producing a polarizing plate, and (3) the method for producing a polarizing plate according to (1), wherein the wavelength of ultraviolet polarized light is 320 nm or less.

The substrate used in the present invention may be a substrate having a polymer layer having a photodimerizable photosensitive group in a side chain and having good transparency. Glass plate such as glass, quartz plate etc., ABS
Resin, acetal resin, (meth) acrylic resin, cellulose acetate, chlorinated polyether, ethylene-vinyl acetate copolymer, fluororesin, ionomer, methylpentene polymer, nylon, polyamide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, etc. Polyester, polyimide, polyphenylene oxide, polyphenylene sulfide, polyallyl sulfone,
Polyarylate, polyethylene, polypropylene, polystyrene, polysulfone, vinyl acetate resin, vinylidene chloride resin, AS resin, vinyl chloride resin, alkyd resin,
Allyl resin, amino resin, urea resin, melamine resin,
Plastic plates and sheets (films) of various materials such as epoxy resin, phenolic resin, unsaturated polyester resin, silicone resin, polyurethane, or their surfaces, silicon oxide, tin oxide, indium oxide, aluminum oxide, titanium oxide, oxide A material coated with a metal oxide such as chromium or zinc oxide, silicon nitride, silicon carbide, or the like is used. Alternatively, a substrate (film) whose surface is covered with a highly reflective metal thin film can also be used.
These substrates may be not only planar substrates but also curved substrates.

In the present invention, a polymer layer having a photodimerizable photosensitive group in a side chain is required. The photosensitive group is a compound that is known to cause a 2 + 2 type photocycloaddition reaction by ultraviolet rays (see Nagamatsu, Inui, Photosensitive Polymer, Kodansha (1977)).

The photodimerizable photosensitive group used in the present invention is, for example, a photosensitive group comprising an aromatic ring or a heterocyclic ring having an aliphatic C ＝ C double bond, and has an aromatic ring or a heterocyclic ring. An unsaturated aliphatic carboxylic acid group can be suitably used, and it is preferable that this carboxylic acid group is bonded to a polymer as a side chain by an ester bond. Specific examples of the carboxylic acid group include a cinnamic acid group, a β-furylacrylic acid group, an α-cyanocinnamic acid group, a p-azidocinnamic acid group, a β-styrylacrylic acid group, and an α-cyano-β −
Examples thereof include a styryl acrylate group, a p-phenylenediacrylate group, a β-naphthyl acrylate group, a diphenylcyclopropenoate group, and a cinnamylidenepyruvate group. Examples of the chemical formulas of these carboxylic acid groups are shown below.

[0011]

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As the photodimerizable photosensitive group other than the unsaturated aliphatic carboxylic acid group containing an aromatic ring or a heterocyclic ring, α-phenylmaleimide group, benzylideneacetophenone group, stilbene group, stilbazole group, coumarin Those containing a group, a pyrone group, a benzophenone group, an anthracene group, or a dibenzazepine group are also preferably used.
Examples of the chemical formulas of these groups are shown below.

[0013]

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These molecules having a photosensitive group are listed as examples of the basic skeleton of the compound, and these skeletons have an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a methoxy group. Group, ethoxy group, propoxy group, alkoxy group such as butoxy group, allyl group, allyloxy group, cyano group, methoxycarbonyl group, alkoxycarbonyl group such as ethoxycarbonyl group, hydroxy group, dimethylamino group, dialkylamino such as diethylamino group One or more substituents selected from a group, a nitro group and the like may be bonded. An alkyl group of C ₁ -C ₆ give similar structure as the liquid crystal molecules, C ₁ ~
Preferred examples of the substituent include a C ₆ alkoxy group, a cyano group, and a C ₁ -C ₆ alkoxycarbonyl group.

There are several methods for preparing a polymer containing a molecule having a photosensitive group. The first is a method in which a photosensitive group is bonded to a polymerizable functional group and polymerized to prepare the photosensitive group. In radical polymerization, a (meth) acryl group is suitable as a functional group, and by using this, a polymer in which a molecule containing a photosensitive group is bonded to a side chain can be easily obtained. Further, the polymer can be made into a polymer by utilizing a polycondensation reaction of polyester, polyamide, polyimide or the like or a polyaddition reaction of polyurethane or the like. In this case, a monomer having two or more functional groups that contribute to a reaction with a molecule containing a photosensitive group may be used.

A second method is to prepare a mixture of a molecule containing a photosensitive group or a polymer prepared by the first method with a resin serving as a binder. This method also includes mixing a molecule containing a photosensitive group with a binder resin, followed by polymerization using a polymerization initiator and cross-linking. As the binder resin used in this method, commercially available poly (meth) acrylic resin, polyester resin, polyurethane resin and the like are particularly preferably used, and other resins can also be used widely.

The third method is to bond a molecule containing a photosensitive group to a polymer such as polyvinyl alcohol and poly (meth) acrylic acid. The bonding may be performed by a chemical reaction such as addition or condensation. For example, a bond forming reaction of ether, ester, amide and the like can be suitably used.

The polymer containing a molecule having a photosensitive group prepared by such a method exhibits performance when provided as a thin film layer on the substrate surface. At this time, the thickness of the thin film is 1 μm.
The following is sufficient, and preferably 0.1 to 0.2 µ. As a method of providing, a spin coating method, a gravure coating method, a dipping method, or the like can be used. Further, it may be provided on the substrate by the Langmuir-Blodgett method.

When the photosensitive group in the polymer layer provided on the substrate is irradiated with ultraviolet rays, preferably ultraviolet rays of 320 nm or less, the photosensitive groups are linearly crosslinked by a 2 + 2 cycloaddition reaction.
The crosslinking direction at that time is random. When the ultraviolet light to be irradiated, preferably ultraviolet light having a wavelength of 320 nm or less, is polarized, directionality occurs in linear cross-linking due to a 2 + 2 cycloaddition reaction. This direction is defined by the polarization plane of the ultraviolet light, and crosslinking proceeds in parallel with the polarization plane.

Next, the operation of irradiating ultraviolet polarized light will be described. The ultraviolet light to be irradiated must have a wavelength corresponding to the energy required for the 2 + 2 cycloaddition reaction. Specifically, far ultraviolet rays having a wavelength of 320 nm or less are preferable, and a mercury lamp, a xenon lamp, a fluorescent lamp, a chemical lamp, an inert gas laser, or the like can be suitably used as a light source. Ultraviolet light emitted from this light source is converted into ultraviolet polarized light using a polarizing element. Specifically, a prism element such as a Glan-Thompson prism is preferable.

The amount of ultraviolet polarized light used varies depending on the type of the photosensitive group.
1 mJ / cm ² or more is required, preferably 10 mJ / cm ²
/ Cm ² to 10 J / cm ² is good. Incidentally, some of the inert gas lasers are polarized, in which case no polarizing element is required.

As described above, when the photosensitive group is irradiated with ultraviolet polarized light, cycloaddition occurs only in the direction of the polarization axis.
Directionality can be given to the linear bridge. Therefore, when using a mask that partially hides the ultraviolet polarized light, the ultraviolet polarized light is partially irradiated, and only that part is cross-linked,
It becomes a pattern. In addition, by diverging or condensing the ultraviolet polarized light to be irradiated on the mask with a lens or the like, it is possible to greatly enlarge or conversely to form an extremely fine pattern. Further, when a polarized laser is used as a light source and combined with a polarization plane rotating element such as a Faraday element, an extremely fine pattern can be freely written.

The dichroic molecule is simply adsorbed on the linear crosslinked structure obtained by the cycloaddition of the photosensitive group, in other words, the dichroic molecular layer is provided on the photocrosslinkable molecular layer. Alone, the molecular axis of the dichroic molecule is aligned in the direction of the molecular axis of the photocrosslinkable molecule, that is, in the direction defined by the polarization axis of the linearly polarized light applied to the photocrosslinkable molecular layer, and the polarization axis is It is fixed and exhibits properties as a polarizing element (plate).

The dichroic molecule used in the present invention is a compound exhibiting a polarizing property when arranged in a certain direction by itself or as an aggregate, and for example, a compound having an aromatic ring structure is preferable. As the aromatic ring structure, in addition to benzene, naphthalene, anthracene, phenanthrene, thiazole, pyridine, pyrimidine, pyridazine,
Heterocycles such as pyrazine and quinoline or quaternary salts thereof, and condensed rings thereof with benzene and naphthalene are particularly preferable. Further, it is preferable that a hydrophilic substituent such as a sulfonic acid group, an amino group or a hydroxyl group is introduced into these aromatic rings.

Examples of dichroic molecules include azo dyes,
Dye-based compounds such as stilbene-based dyes, pyrazolone-based dyes, triphenylmethane-based dyes, quinoline-based dyes, oxazine-based dyes, thiazine-based dyes, and anthraquinone-based dyes can be given. Water-soluble ones are preferred, but not limited thereto. Further, it is preferable that a hydrophilic substituent such as a sulfonic acid group, an amino group, or a hydroxyl group is introduced into these dichroic molecules. Specific examples of dichroic molecules include, for example, C.I. I. Direct Blue 67, C.I. I.
Direct Blue 90, C.I. I. Direct
Green 59, C.I. I. Direct Viol
et 48, C.I. I. Direct Red 39,
C. I. Direct Red 79, C.I. I. Dir
ect Red 81, C.I. I. Direct Red
83, C.I. I. Direct Red 89, C.I.
I. Direct Orange 39, C.I. I. Di
Rectrange 72, C.I. I. Acid Re
d 37 and the like.
JP-A-1-172906, JP-A-1-172290
7, JP-A-1-183602, JP-A-1-2481
No. 05 and JP-A-1-265205. The structures of typical dyes are shown below.

[0026]

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[0027]

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In the polymer layer containing a molecule having a photosensitive group,
Next, a method for anisotropically adsorbing these dichroic molecules will be described. The above dichroic molecule alone or a mixture of two or more dichroic molecules is dissolved in a hydrophilic solvent such as water, methanol, ethanol or the like or a water-containing solvent thereof. The concentration is preferably 0,1.
1 to 10 w / w%, more preferably 0.5 to 5 w / w%
It is about. Also, a surfactant can be added to this solution. As the surfactant, any of a cationic surfactant, a nonionic surfactant, and an anionic surfactant can be used, but a nonionic surfactant is preferable. Next, the dichroic molecule solution is dropped on the substrate surface, and a dichroic molecule layer having a uniform thickness is provided by a coater or a spin coating method.
Alternatively, a substrate having a polymer layer containing a molecule having a photosensitive group is immersed in the solution of the dichroic molecule, and is then pulled up. In order to obtain a uniform concentration of dichroic molecules, it is preferable to keep the pulling speed constant. The thickness of the dichroic molecular layer is preferably thinner from the viewpoint of improving the polarization characteristics, and is, for example, preferably 10 μm or less, particularly preferably 0.1 to 2 μm.

The substrate on which the dichroic molecule solution is adhered is dried to form a solid state dichroic molecular layer, whereby a polarizing element (plate) is obtained. Drying conditions vary depending on the type of solvent, the type of dichroic molecule, the amount of the applied dichroic molecule solution, the concentration of dichroic molecule, etc., but the temperature is from room temperature to 100 ° C, preferably from room temperature to 50 ° C. , Humidity is 20
-80% RH, preferably about 30-70% RH.

The anisotropically adsorbed dichroic molecular layer thus prepared is in a solid state such as, for example, amorphos or a crystal. However, the dichroic molecular layer usually has a slightly lower mechanical strength. It is preferable to provide a protective layer on the surface. This protective layer is usually formed by coating a dichroic molecular layer with a UV-curable or thermosetting transparent polymer film, or laminating with a transparent polymer film such as a polyester film or a cellulose acetate film. It is provided by a coating method.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, parts are by weight unless otherwise specified. The polarization ratio was calculated by the following formula. Polarization ratio ρ (%) = {(Y ₂ −Y ₁ ) / (Y ₂ + Y ₁ )}
^1/2 × 100 (Y ₂ : parallel transmittance (%), Y ₁ : orthogonal transmittance (%))

Example 1 10 parts of vinyl cinnamate (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in benzene to form a 20% by weight solution, and azobisisobutyronitrile was used as an initiator at 60 ° C. in a dark place under degassing. For 4 hours. A solution composed of 10 parts of the polymer having cinnamic acid and 90 parts of toluene is spin-coated on hard glass. This substrate was dried by heating at 105 ° C. for 10 minutes.

An ultra-high pressure mercury lamp of 500 W / h is used as a light source, and the light is transmitted through a Glan-Thompson-type polarizing element.
Linearly polarized light including far ultraviolet light of nm or less. The linearly polarized light was applied to the coated surface of the substrate placed parallel to the polarization axis of the polarizing plate at room temperature for 10 minutes from a distance of 50 cm.

C. I. Direct Blue 67
10 parts of Emulgen 108 (nonionic surfactant:
(Manufactured by Kao Corporation) and diluted with 89 parts of distilled water to obtain an aqueous solution. This dye aqueous solution was spin-coated on the linearly polarized light irradiation surface of the substrate and dried under the conditions of 25 ° C. and 50% RH, and the transmittance T at a wavelength of 550 nm T = 42.0.
A polarizing element (plate) with 3% and a polarization ratio ρ = 95.2% was obtained.

Example 2 Vinyl cinnamate and methyl methacrylate were dissolved in 200 parts of benzene at a molar ratio of 5: 5 to prepare a 20% by weight solution, and polymerization was carried out in the same manner as in Example 1. Obtained polymer 10
And a solution consisting of 90 parts of toluene and 90 parts of toluene was spin-coated on hard glass, dried by heating at 105 ° C. for 10 minutes, and then irradiated with linearly polarized light in the same manner as in Example 1. Then, on the surface irradiated with linearly polarized light, C.I. I. Direct Blue 6
75 parts and C.I. I. Direct Orange 72
5 parts were mixed, and 1 part of Emulgen 108 was added, and a dye aqueous solution diluted with 89 parts of distilled water was applied by spin coating.
When dried under the condition of 0% RH, a polarizing element (plate) having a transmittance T of 43.2% at a wavelength of 550 nm and a polarization rate ρ of 90.4% was obtained.

Example 3 10 parts of commercially available polyvinyl alcohol (polymerization degree: 500, saponification degree: 96%) and 15 parts of triethylamine were dispersed in 300 ml of n-hexane, and citric acid chloride (manufactured by Tokyo Chemical Industry Co., Ltd.) with stirring. ) 40 parts were added dropwise. After the reaction, the reaction mixture was washed with diluted hydrochloric acid to remove triethylamine, washed with water and dried. 10 parts of the obtained dried product was dissolved in 90 parts of toluene, and applied to a 75 μm-thick PET film by using a dipping method. This film was irradiated with linearly polarized light in the same manner as in Example 1. Then, on the surface irradiated with linearly polarized light, C.I. I. Direct Blue 675 (5 parts) and Emulgen 108 (Kao Co., Ltd.) (1 part) were added, and a dye aqueous solution diluted with 94 parts of distilled water was applied by spin coating.
When dried under the condition of% RH, a polarizing element (plate) having a transmittance T at a wavelength of 550 nm T = 41.2% and a polarization rate ρ = 93.3% was obtained.

Example 4 In the same manner as in Example 1, a methacrylate polymer having a benzalacetophenone group in the side chain was synthesized, and a solution consisting of 10 parts of this polymer and 90 parts of toluene was applied by a gravure coating method. It was applied to a PET film. This film was irradiated with linearly polarized light in the same manner as in Example 1. Then, on the surface irradiated with linearly polarized light, C.I. I. Direct
After adding 675 parts of Blue and 1 part of Emulgen 108 and spin-coating a dye aqueous solution diluted with 94 parts of distilled water,
When dried under the conditions of 5 ° C. and 50% RH, the wavelength was 550.
Transmittance at nm = 40.2%, Polarization ρ = 87.
A 9% polarizing element (plate) was obtained.

[0038]

According to the present invention, a polymer layer containing a molecule having a photosensitive group is provided on the substrate surface layer, and the photosensitive group is irradiated with ultraviolet polarized light causing a 2 + 2 cycloaddition reaction to form a linear layer. After crosslinking, one or more dichroic molecules are adsorbed to the polymer layer, whereby a polarizing element (plate) capable of drawing an extremely fine polarization pattern can be manufactured. Further, dichroic molecules can be more stably aligned than the method described in JP-A-7-261024.

Claims (3)

[Claims] 1. A polymer layer having a photodimerizable photosensitive group in a side chain on a substrate is irradiated with ultraviolet polarized light, and then a layer containing dichroic molecules is provided on the layer. Method for manufacturing a polarizing plate. 2. The photodimerizable photosensitive group is an aliphatic C ＝ C
2. The method for producing a polarizing plate according to claim 1, wherein the photosensitive group is a photosensitive group comprising an aromatic ring or a hetero ring having a double bond. 3. The method for producing a polarizing plate according to claim 1, wherein the wavelength of the ultraviolet polarized light is 320 nm or less.