JP2009003250A - Method for producing dichroic polarizing element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of applying a dichroic dye-containing solution uniformly even on a substrate having a rugged surface, and simply and highly precisely manufacturing a dichroic polarizing element having excellent polarization characteristics. <P>SOLUTION: In the method for manufacturing the dichroic polarizing element by applying the dichroic dye-containing solution having lyotropic liquid crystal property on the substrate surface, the dichroic dye-containing solution is applied by using a felt member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a dichroic polarizing element used in a liquid crystal display device or the like, and more particularly to a method for manufacturing a dichroic polarizing element having a dichroic dye alignment film.

  As a polarizing element used in a liquid crystal display device or the like, a dichroic polarizing element obtained by uniaxially stretching a polyvinyl alcohol resin film or the like and adsorbing and orienting a dichroic material such as an iodine compound on the surface is widely used. However, a dichroic polarizing element in which a dichroic dye alignment film containing a dichroic dye is formed on a substrate from the viewpoint of heat resistance or the like has been studied.

  As a method for producing a dichroic polarizing element having the above dichroic dye alignment film, the dichroic dye is aligned by the flow of the liquid crystal compound itself, which is referred to as fluid alignment, so that the dichroic dye is formed on the substrate. Applying a solution containing a dichroic dye by using coating means such as curtain coating, extrusion coating, roll coating, dip coating, spin coating, printing coating, spray coating, slide coating, etc. The method of forming the dichroic dye alignment film shown is proposed (for example, Patent Document 1 and Patent Document 2).

  In addition, in order to control the orientation of the dichroic dye, a solution containing the dichroic dye is applied to a substrate having a rubbed polyimide alignment film by spin coating, spray coating, bar coating, roll coating. A method of coating by a coating method such as a blade coating method has been proposed (for example, Patent Document 3). In this rubbing treatment, the polyimide alignment film formed on the surface of the base material is rubbed with a roller having a cloth such as nylon attached to cause anisotropy on the surface of the base material. This is for initial orientation in the direction.

Furthermore, a liquid crystal polymer thin film having a photoactive group is formed on a base material, and desired anisotropy is expressed on the surface of the thin film by irradiating the thin film with linearly polarized light through a micropatterned mask. Then, a photo-alignment method has been proposed in which a solution containing a dichroic dye is applied on a thin film by spin coating to align the dichroic dye (for example, Patent Document 4).
US Patent No. 24000877 JP 2002-90526 A JP 2006-323377 A JP 2001-159713 A

  By the way, the dichroic polarizing element as described above uses a polymer film or glass having a flat surface as a base material. However, when mass production and thinning of a liquid crystal display device and the like are intended, other It is preferable to form the polarizing element directly on the member. However, for example, when an optical member having a concavo-convex surface such as a microlens or a lenticular lens is used as a base material and a dichroic dye alignment film is directly formed on the base material, the dichroic dye is not applied by the above-described coating means. There is a problem that shear stress is not easily applied to the dichroic dye contained in the contained solution, and the solution accumulates in the recess, and the surface shape of the substrate is not reflected in the formed dichroic dye alignment film.

  The present invention has been made to solve the above-described conventional problems, and enables uniform application of a dichroic dye-containing solution to a substrate having an uneven surface, and thus has excellent polarization characteristics. It is an object of the present invention to provide a method capable of producing a chromatic polarizing element easily and with high accuracy.

The present invention is a method for producing a dichroic polarizing element produced by applying a dichroic dye-containing solution having lyotropic liquid crystal properties on a substrate surface,
In the production method, the dichroic dye-containing solution is applied using a felt member.
According to the manufacturing method, since the felt member has pores therein, the dichroic dye-containing solution can be held. Further, when the felt member comes into contact with the substrate surface, the felt member is easily deformed by the internal pores. For this reason, even if the substrate has an uneven surface, the felt member can follow the unevenness. Accordingly, the solution does not remain in the concave portion, and sufficient shear stress can be applied not only to the convex portion but also to the dichroic dye applied to the concave portion, and uniform application can be performed.

  The surface of the base material may have an uneven surface. According to the said manufacturing method, a dichroic dye containing solution can be uniformly apply | coated to the base-material surface which has an uneven surface.

  The uneven surface may have an uneven height of 0.5 μm or more and 500 μm or less. According to the said manufacturing method, a dichroic dye containing solution can be uniformly apply | coated also on the base material which has a fine unevenness | corrugation.

  The substrate has an optical functional layer, the uneven surface is formed on the optical functional layer, and the dichroic dye-containing solution may be applied to a surface of the optical functional layer. According to the above manufacturing method, for example, even when an optical member including an optical functional layer having an uneven surface such as a microlens array sheet or a lenticular lens sheet is used as a substrate, uniform coating can be performed. A dichroic dye alignment film reflecting the surface shape of the material can be formed.

  The surface of the substrate may be hydrophilized. According to the said manufacturing method, since the wettability with respect to the dichroic dye containing solution of the said base material surface is improved, more uniform application | coating can be performed.

  The felt member preferably has a porosity of 45% or more and 60% or less. If it is the felt member which has the said porosity, since a felt member is easy to deform | transform by contact with a base material, a felt member can fully follow a fine unevenness | corrugation.

  The felt member preferably has a polyester fiber. Since the felt member having polyester fibers is excellent in elasticity, the felt member can sufficiently follow even the fine irregularities.

  According to the present invention, a dichroic dye-containing solution can be uniformly applied even to a substrate having an uneven surface, and a dichroic polarizing element having excellent polarization characteristics is easily and accurately manufactured. be able to.

  FIG. 1 is a partial schematic diagram illustrating an example of a coating process of the method for manufacturing a dichroic polarizing element according to the present embodiment. As shown in FIG. 1, in the coating step of the present embodiment, the felt member 2 is brought into contact with one surface of the substrate 1 having an uneven surface, and the dichroic dye-containing solution 3 is transferred from the felt member 2 to the substrate 1. Supplied on top. When the solution is applied to the substrate 1 having an uneven surface using a coating means such as a die coater or a gravure coater, the die slit width and the gravure roll diameter are much larger than the uneven pitch, so that the dichroic dye-containing solution is in the recess. It is easy to accumulate, and since the die slit and the gravure roll do not enter the recess, shear stress is hardly applied to the dichroic dye contained in the dichroic dye-containing solution in the recess. For this reason, the solution accumulates in the recesses, and not only the surface shape of the base material is hardly reflected in the formed dichroic dye alignment film, but also the resulting dichroic dye alignment film tends to have low orientation. On the other hand, since the felt member has pores inside, the felt member 2 can be easily deformed by contact with the substrate 1 and can follow the unevenness. As a result, the dichroic dye-containing solution can be applied while imparting sufficient shear stress to the dichroic dye applied to the recesses.

  As the base material 1, for example, a polymer film or glass can be used. Specific examples of the polymer film include polyolefins such as triacetyl cellulose, polyethylene, polypropylene, and poly (4-methylpentene-1), polyimide, polyimide amide, polyether imide, polyamide, polyether ether ketone, and polyether. Ketone, polyketone sulfide, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose plastics, epoxy resin And a polymer film made of a phenol resin or the like. Specific examples of the glass include quartz glass, Pyrex (registered trademark) glass, and synthetic quartz. The substrate 1 may be either a single plate or a long shape, but is preferable because continuous application is possible by using a long substrate.

  The uneven surface may be directly formed on the surface of the polymer film or glass as described above, or may be formed on the surface of an optical functional layer made of an ultraviolet curable resin or the like formed thereon. . As a base material which has an optical functional layer in which an uneven surface is formed, for example, an optical sheet used for a liquid crystal display device can be exemplified. By directly providing a dichroic dye alignment film on a substrate having such an optical functional layer, it is not necessary to separately use a substrate for forming the dichroic dye alignment film, resulting in mass production and thinning. In addition, a decrease in transmittance due to a polymer film or glass can be suppressed. FIG. 2 is a schematic cross-sectional view illustrating a substrate 1 having an optical functional layer 4 on a main material 5, and FIG. 2 (a) is a lenticular lens sheet provided with an optical functional layer 4 having columnar lens-shaped irregularities. 2B shows a prism sheet provided with the optical functional layer 4 having prism-shaped irregularities, and FIG. 2C shows a microlens array provided with the optical functional layer 4 having micro-lens-shaped irregularities. FIG. 2D shows a diffusion sheet provided with an optical functional layer 4 having random irregularities. As the main material 5, the same polymer film or glass as described above can be used. The uneven height is preferably 0.5 μm or more and 500 μm or less, although it depends on the type of the substrate 1 to be used. Since the felt member can sufficiently follow such fine unevenness, a dichroic dye alignment film reflecting the uneven shape can be formed uniformly. When the dichroic dye alignment film of this embodiment is used as a polarizing filter for various liquid crystal display devices such as LCDs and OLEDs, an electrode substrate or the like constituting these display elements may be used as a base material. Good.

  The surface of the substrate 1 may be subjected to a hydrophilic treatment in order to improve the wettability with respect to the dichroic dye-containing solution 3. Specific examples of such hydrophilic treatment include corona discharge treatment, plasma treatment, UV ozone treatment, glow discharge treatment, and the like. Among these, the corona discharge treatment is particularly preferable. Further, an alignment film such as polyimide may be further formed on the surface of the substrate 1.

  Specific examples of the felt member 2 include felt members made of natural fibers such as wool and cotton, felt members made of synthetic fibers such as polyester, acrylic, nylon, and rayon, or these fibers are polyester, melamine, and the like. A felt member bonded with the above resin may be used. The material of the felt member 2 can be appropriately selected depending on the coating thickness of the dichroic dye-containing solution, the characteristics of the dichroic dye alignment film, the material and shape of the substrate, and the like. Among these, the felt member having polyester fiber is excellent in elasticity, and is particularly preferably used when a substrate having a fine uneven surface is used. Further, the porosity of the felt member 2 is preferably 45% or more and 60% or less, and more preferably 50% or more and 60% or less. Since the felt member having the porosity is easily deformed by contact with the base material, the felt member can follow even fine irregularities. The thickness of the fiber of the felt member 2 is not particularly limited, but is preferably 0.1 denier or more and 6 denier or less.

  Examples of dichroic dyes include compounds that exhibit lyotropic liquid crystallinity under certain solvent composition, dye concentration, and temperature conditions. Such a dichroic dye forms an aggregate which is called a chromonic liquid crystal phase. For this reason, a dichroic dye alignment film having polarization is obtained by aligning the aggregates in a certain direction on the substrate surface. In addition, since a plurality of molecules are associated, the resulting dichroic dye alignment film is excellent in light fastness.

  The dichroic dye preferably has a hydrophilic group. By using a dichroic dye having a hydrophilic group, the orientation of the dichroic dye can be further improved. Such a hydrophilic group is preferably at least one selected from the group consisting of a sulfonic acid group, a carboxylic acid group, an amino group, and a hydroxyl group that are easy to introduce and exhibit high hydrophilicity. The dichroic dye may have one kind of hydrophilic group or may have two or more kinds of hydrophilic groups. The molecular weight of the dichroic dye is not particularly limited, but the number average molecular weight is preferably 500 or more and 5,000 or less. By using a dichroic dye having a molecular weight within the above range, the orientation can be further improved.

  Suitable dichroic dyes include, for example, compounds having an aromatic ring structure with high polarization ability. Examples of such aromatic rings include aromatic rings such as benzene, naphthalene, anthracene, and phenanthrene; heterocycles such as thiazole, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, and quaternary salts thereof; aromatic rings and heterocycles The fused ring is preferred. Moreover, said hydrophilic group may be introduce | transduced into the aromatic ring.

  Other suitable dichroic dyes include, for example, azo dyes; cyanine dyes; anthraquinone dyes including condensation systems such as indanthrone; stilbene dyes; pyrazolone dyes; perylene dyes; Triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye, quinophthalone dye, indigo dye, thioindigo dye, and the like. Among these, water-soluble dyes are preferable. Specific examples of the dichroic dye include C.I. I. Direct Blue 1, C.I. I. Direct Blue 15, C.I. I. Direct Blue 67, C.I. I. Direct Blue 78, C.I. I. Direct Blue 83, C.I. I. Direct Blue 90, C.I. I. Direct Blue 98, C.I. I. Direct Blue 151, C.I. I. Direct Blue 168, C.I. I. Direct Blue 202, C.I. I. Direct Green 51, C.I. I. Direct Green 59, C.I. I. Direct Green 85, C.I. I. Direct Violet 9, C.I. I. Direct Violet 48, C.I. I. Direct Red 2, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Orange 39, C.I. I. Direct Orange 41, C.I. I. Direct Orange 49, C.I. I. Direct Orange 72, C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 26, C.I. I. Direct Yellow 44, C.I. I. Direct Yellow 50, C.I. I. Acid Red 37, C.I. I. No. 27865, C.I. I. No. 27915, C.I. I. No. 27920, C.I. I. No. 29058, C.I. I. No. 29060, disofondanthrone, disulfo-N, N'-dilylyperylenetetracarbodiimide, and azo dyes described in JP-A-2005-255846. These may be used alone or in combination.

  The dichroic dye-containing solution can be prepared, for example, by mixing the dichroic dye with a solvent at 60 to 95 ° C. and stirring to dissolve the dichroic dye and then returning to room temperature. As the solvent, water and water-miscible organic solvents are preferable. Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; glycols such as ethylene glycol and diethylene glycol; cellosolves such as methyl cellosolve and ethyl cellosolve; dimethylformamide (DMF); dimethyl sulfoxide ( DMSO); N-methylpyrrolidone (NMP); dimethylacetamide (DMAc); aprotic polar solvents such as dimethylimidazoline (DMI) are preferred. In particular, a mixed solvent containing water as a main component (50% by volume or more) and containing the above organic solvent is preferable. The concentration of the dichroic dye in the dichroic dye-containing solution depends on the solubility of the dye and the concentration at which the lyotropic liquid crystal state is formed, but the mass ratio of the entire solution, preferably 0.1% by mass or more More preferably, it is 0.5% by mass or more, preferably 50% by mass or less, more preferably 30% by mass or less. If the concentration is within the above range, the influence of aggregates and undissolved substances of the dichroic dye is reduced, and there is no risk of impairing the anisotropy (orientation) of the dichroic dye alignment film. A dichroic dye alignment film with a sufficient thickness can be formed.

  The dichroic dye-containing solution 3 may contain an additive such as a surfactant as necessary in order to improve the wettability to the substrate 1 and the coating property. As such a surfactant, any of anionic, cationic, and nonionic surfactants can be used without limitation. The concentration of the surfactant in the dichroic dye-containing solution is preferably 0.05% by mass or more and 5% by mass or less in terms of the mass ratio of the entire solution. If the concentration is within the above range, there is no possibility that the micelle formation of the surfactant affects the anisotropy of the dichroic dye alignment film, and the dichroic dye-containing solution 3 is wetted with respect to the substrate 1. Can be improved.

When the dichroic dye-containing solution 3 is applied on the substrate 1 using the felt member 2, the prepared dichroic dye-containing solution is used to cause the felt member 2 to hold the dichroic dye-containing solution 3. 3 may be performed by immersing the felt member 2 into the felt member 2, or by supplying the felt member 2 with the dichroic dye-containing solution 3 from a supply tank or the like. When using the elongate base material 1, it is preferable to apply | coat, supplying the dichroic dye containing solution 3 to the felt member 2 continuously. The amount of the dichroic dye-containing solution 3 held on the felt member 2 is preferably 0.5 g / cm ³ or more and 1.0 g / cm ³ or less.

  After applying the dichroic dye-containing solution 3 to the surface of the substrate 1 using the felt member 2, the dichroic dye alignment film having polarization is obtained by drying. The contact length in the application direction of the felt member 2 brought into contact with the substrate 1 is not particularly limited, but is preferably 1 mm or more and 50 mm or less. The drying temperature is preferably 0 ° C. or higher and 120 ° C. or lower. Although the thickness of the dichroic dye alignment film to be formed varies depending on the application, it is usually preferably 50 nm or more and 1000 nm or less.

  In the dichroic polarizing element of the present embodiment, a protective film may be further formed on the dichroic dye alignment film. Specific examples of such a protective film include transparent polymer films such as films made of triacetate, acrylic, polyester, triacetyl cellulose, polyurethane, and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples. In the following description, “part” means “part by mass”.

[Example 1]
(Preparation of base material)
An ultraviolet curable resin is supplied from a die coater onto a roll plate having a concavo-convex pattern for forming a microlens array, and pressed against the resin-coated surface of the roll plate while running a polyethylene terephthalate (PET) film (thickness: 100 μm), A microlens array sheet was produced by transferring the ultraviolet curable resin onto a film and irradiating the transferred ultraviolet curable resin with ultraviolet rays to cure the ultraviolet curable resin. When the shape dimension of the produced microlens array sheet was measured by an SEM photograph, the radius of the lens plane was 15 μm, the lens height was 15 μm, and the radius of curvature of the lens surface was 15 μm. The shortest distance from the lens edge to the adjacent lens edge was 7.8 μm, and the flat portion ratio of the sheet was 43%.
The surface of the microlens array sheet produced as described above was subjected to corona discharge treatment at room temperature in an air atmosphere. For the corona discharge treatment, a corona discharge treatment apparatus (manufactured by Kasuga Denki Co., Ltd., treatment roll surface material: hard silicone rubber) was used.

(Production of dichroic polarizing element)
First, 15 parts of dichroic dye (CI Direct Blue 67) was added to 85 parts of water (resistivity: 16 MΩ · cm or more) at 80 ° C. and mixed by stirring to dissolve the dichroic dye. Next, after cooling the solution to room temperature, 50 parts of ethanol was added to the solution to cause precipitation, and the dichroic dye was purified by collecting the precipitate.
15 parts of the dichroic dye purified as described above is added to 85 parts of water at 80 ° C., and the dichroic dye is dissolved by stirring and mixing, and then naturally cooled to room temperature and then dichroic dye. A containing solution was prepared. The solution thus prepared had a viscosity of 44 mPa · s and a pH of 7.3.

By immersing a felt member (made of polyester fiber, fiber thickness: 3 denier, porosity: 50 to 60%) in the prepared dichroic dye-containing solution, dichroism of 0.85 g / cm ³ is applied to the felt member. Impregnated with dye-containing solution. Then, after applying the dichroic dye-containing solution by causing the felt member to contact the sheet surface with a contact length of 5 mm in the application direction while running the microlens array sheet prepared above at a conveyance speed of 5 m / min, Naturally dried. After drying, the sheet was cut into a predetermined size to produce a dichroic polarizing element.

[Example 2]
(Preparation of base material)
A lenticular lens sheet was prepared in the same manner as the base material of Example 1 except that a roll plate having a concavo-convex pattern for forming a lenticular lens was used as the roll plate. It was confirmed that the cross-sectional shape of each cylindrical lens of the produced lenticular lens sheet was an elliptical arc shape with the end point of the long axis as the lens apex. Further, when the shape dimension of the lenticular lens sheet was measured by SEM photographs, the major axis diameter of the lens was 100 μm, the minor axis diameter of the lens was 58.8 μm, the lens height was 23.7 μm, the contact angle was 70 degrees, and the arrangement pitch Was 50 μm.
The surface of the lenticular lens sheet produced as described above was subjected to corona discharge treatment at room temperature and in an air atmosphere in the same manner as in Example 1.

(Production of dichroic polarizing element)
A dichroic polarizing element was produced in the same manner as in Example 1 except that the lenticular lens sheet produced as described above was used.

[Comparative Example 1]
A dichroic polarizing element was produced in the same manner as in Example 1 except that a micro gravure coater was used as the coater instead of the felt member.

[Comparative Example 2]
A dichroic polarizing element was produced in the same manner as in Example 2 except that a micro gravure coater was used as the coater instead of the felt member.

  The surface shapes of the dichroic polarizing elements of Examples and Comparative Examples produced as described above were observed with an electron microscope. As a result, the dichroic polarizing element of the comparative example produced by applying the dichroic dye-containing solution using a micro gravure coater reflects the surface shape of the base material because the dichroic dye is buried in the recesses. Not confirmed. On the other hand, the dichroic polarizing element of the Example produced by apply | coating the dichroic dye containing solution using a felt member reflected the surface shape of each base material, and the thickness of 300 nm was uniform. It was confirmed that a chromatic dye alignment film was formed. Moreover, when the polarization characteristic of the dichroic polarizing element produced in the Example was measured, it was confirmed that it has a transmission axis in the coating direction and exhibits excellent polarization performance.

It is the partial schematic which shows an example of the application | coating process of the manufacturing method of the dichroic polarizing element which concerns on embodiment of this invention. FIG. 2 is a schematic cross-sectional view illustrating a substrate having an optical functional layer according to an embodiment of the present invention. FIG. 2A is a diagram showing a lenticular lens sheet provided with an optical functional layer having columnar lens-shaped irregularities. 2 (b) shows a prism sheet provided with an optical functional layer having prism-shaped irregularities, and FIG. 2 (c) shows a microlens array sheet provided with an optical functional layer having microlens-shaped irregularities. (D) shows the diffusion sheet provided with the optical function layer which has a random unevenness | corrugation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Felt member 3 Dichroic dye containing solution 4 Optical functional layer

Claims (7)

A method for producing a dichroic polarizing element produced by applying a dichroic dye-containing solution having lyotropic liquid crystal properties on a substrate surface,
A production method comprising applying the dichroic dye-containing solution using a felt member.   The manufacturing method according to claim 1, wherein the surface of the substrate has an uneven surface.   The manufacturing method according to claim 2, wherein the uneven surface has an uneven height of 0.5 μm or more and 500 μm or less.   The base material has an optical functional layer, the uneven surface is formed in the optical functional layer, and the dichroic dye-containing solution is applied to a surface of the optical functional layer. Item 4. The production method according to Item 2 or 3.   The manufacturing method according to claim 1, wherein the surface of the base material is subjected to a hydrophilic treatment.   The manufacturing method according to claim 1, wherein the felt member has a porosity of 45% or more and 60% or less.   The said felt member has a polyester fiber, The manufacturing method of any one of Claims 1-6 characterized by the above-mentioned.

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