JP2001133607A - Light scattering layer, light scattering plate, color filter and liquid crystal display device utilizing them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light scattering layer, a light scattering plate and a color filter, having high dispersibility of particulates into a matrix transparent resin, improved frontal scattering characteristics and superior light transmittivity and improved scattering characteristics, while maintaining high light trasmittivity and a liquid crystal display device utilizing them. SOLUTION: This light scattering layer, a light scattering plate and the color filter are characterized by scattering transmitted light, by having a resin layer composed of a transparent resin in which inorganic particulates are dispersed. The inorganic particulates are polygonal particulates, having a refractive index different from that of the resin and essentially having no fracture face consisting of the particulates with an L/S ratio <=2.0, expressing lengths of the long and short axes of the particulates as L and S respectively. The number- average particle size of the particulates is >=0.1 μm and <=20.0 μm. Their particle size distribution D90/D10 is <=7 expressing the particle sizes at cumulative frequencies of 10% and 90% in the cumulative particle size distribution counted from the minimum size side as D10 and D90 respectively. The liquid crystal display device utilizes them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light scattering layer, a light scattering plate, a color filter, and a liquid crystal display device using the same in order to increase a viewing angle and improve display quality.

[0002]

2. Description of the Related Art In recent years, liquid crystal display panels have features such as thinness, light weight, and low power consumption, and have been rapidly spread in recent years as display devices replacing CRTs (CRTs), and the demands thereof have been increasing. Further, they are used in various fields, and the market trend thereof is toward larger screens and higher definition. Liquid crystal display panels have the advantages of being thin and being driven at low power, but have insufficient light transmittance, luminance, and viewing angle. In particular, there is a strong demand for improvements in viewing angles that are much narrower than CRTs. . Therefore, as one method of widening the viewing angle of a liquid crystal display panel, there is a method of scattering light transmitted through the liquid crystal display panel in all directions and averaging the light in the visual field to widen the viewing angle. As a method of scattering light, a method using a scattering plate is generally used. Techniques for scattering light with a scattering plate include those that disperse fine particles in the scattering plate and thereby scatter light, those that roughen the surface of the scattering plate and scatter light, and those that use a diffraction grating on the surface of the scattering plate. And the like, which form the fine structure and scatter light. Among them, the method of scattering light by fine particles dispersed in a scattering plate is most often used.

[0003] Further, as a method of incorporating a scattering layer into a liquid crystal panel, a method of bonding a light diffusion film to the surface of the liquid crystal panel, and a method of bonding a light diffusion adhesive having a light scattering function as an adhesive when bonding a polarizing plate are used. There have been proposed a method of using, a method of forming a light scattering layer in which fine particles are dispersed in a resin on a color filter, and the like, and several methods have been disclosed.
For example, JP-A-7-28055 discloses a method of disposing a light diffusion layer in which fine particles such as titanium oxide and aluminum oxide are dispersed in a transparent resin on the observation substrate side. Japanese Patent Application Laid-Open No. 10-206837 discloses a light-scattering layer in which a high-refractive-index transparent pigment such as cerium oxide having an average particle size in the range of 0.4 μm to 4 μm and a refractive index higher than 1.8 is dispersed in a resin. Is disposed on the observation substrate side. Japanese Patent Application Laid-Open No. 7-218705 discloses a light diffusion film in which acrylic fine particles having an average particle size of 1 μm to 50 μm are dispersed.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin having a high dispersibility in a transparent resin serving as a matrix,
And, it is excellent in improvement of forward scattering characteristics and light transmittance, and
An object of the present invention is to provide a light scattering layer, a light scattering plate, a color filter, and a liquid crystal display using the same, which have improved scattering characteristics while maintaining high light transmittance.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by using specific fine particles as a scattering material, the forward scattering characteristics have been improved and the light transmittance has been improved. The inventors have found that excellent light scattering layers, light scattering plates, and color filters can be formed, and have reached the present invention.

That is, the present invention provides the following [1] to
The invention of [7] is provided. [1] Polyhedral fine particles having substantially no crushed surface having different refractive indices, and when the long axis length of the fine particles is L and the short axis length is S, the L / S ratio is 2.0 or less. It is composed of certain fine particles, and the number average particle diameter of the fine particles is 0.1 μm or more and 20.0 μm.
m or less, and a cumulative 10 from the fine particle side of the cumulative particle size distribution.
% And a cumulative 90% particle diameter of D10 and D90, respectively, where the D90 / D10 value has a particle size distribution of 7 or less. A light scattering layer characterized by scattering. [2] A light-scattering plate according to [1], wherein the light-scattering resin layer in which the inorganic particles are dispersed is used on the surface of the scattering plate or in the scattering plate. [3] A polarizing plate, elliptically polarizing plate or retardation plate comprising the light scattering plate according to [2]. [4] At least one side outside or inside the liquid crystal cell,
A liquid crystal display device comprising the light scattering plate according to the above [2]. [5] A liquid crystal display device comprising the polarizing plate, the elliptically polarizing plate, or the retardation plate according to [3] above at least one side of a liquid crystal cell. [6] A color filter for a liquid crystal display device, wherein in the light scattering layer according to the above [1], a light scattering resin layer in which the inorganic particles are dispersed is provided on one or both sides of a transparent substrate or on a color filter layer. [7] A liquid crystal display device comprising the color filter for a liquid crystal display device according to the above [6] as a component thereof.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The light-scattering layer in the present invention has a light-scattering resin layer in which inorganic fine particles having different refractive indices from the transparent resin are dispersed in a transparent resin serving as a matrix in order to impart a light-scattering effect. The inorganic fine particles to be used are polyhedral fine particles having substantially no crushed surface. When the long axis length of the fine particles is L and the short axis length is S, the L / S ratio is 2.0 or less. Wherein the number average particle diameter of the fine particles is 0.1 μm or more and 20.0 μm or less, and D10 and D90 are D90 and D90, respectively, when the particle diameters of 10% and 90% from the fine particle side in the cumulative particle size distribution are D10 and D90, respectively. These inorganic fine particles have a particle size distribution of / D10 of 7 or less.

The inorganic fine particles used in the present invention include metal oxides and the like, preferably oxides of metals belonging to Groups IIIa to IVb in the periodic table, more preferably aluminum oxide, titanium oxide, and the like. Examples include yttrium oxide and yttrium aluminum garnet (YAG). Above all, the refractive index is closer to the refractive index of the transparent resin serving as the matrix, since the backscattering is reduced, the alumina fine particles having a small refractive index difference with the transparent resin serving as the matrix are preferable, and in particular, in the present invention, D is a maximum particle diameter parallel to the hexagonal lattice plane of α-alumina, which is a hexagonal close-packed lattice, and H is a particle diameter perpendicular to the hexagonal close-packed lattice plane.
, When the D / H ratio is 0.5 or more and 2.0 or less, the α-alumina fine particles have a number average particle size of 0.1 μm or more and 20.0 μm or less, and a cumulative particle size distribution Where D10 and D90 are the particle diameters of 10% and 90%, respectively, from the fine particle side of D90 / D10.
Are preferably fine particles having a particle size distribution of 7 or less.

Further, the number average particle diameter of the inorganic fine particles is 0.1.
1 μm or more and 20.0 μm or less, preferably,
It is 0.4 μm or more and 10.0 μm or less. Further, when the number average particle diameter is 20.0 μm or more, the unevenness of the surface of the light-scattering resin layer becomes large, and it becomes difficult to flatten. If flattening is attempted, the film thickness will be further increased, which is not preferable in terms of cost and thinning of the liquid crystal panel.

The method for producing alumina powder of the present invention is described in, for example, JP-A-6-191833 and JP-A-6-191.
835, JP-A-6-191836, JP-A-7-206430 and the like can be used. In the light-scattering layer, the amount of the inorganic fine particles of the present invention added to the transparent resin serving as the matrix is such that, if the proportion of the inorganic fine particles is too large, the scattering effect increases but the light transmittance decreases, and It is not preferable because it becomes whitish and lowers the display quality.
In addition, it is not preferable because the particles easily aggregate. If the proportion of the inorganic fine particles is too small, the scattering effect is reduced and an effective scattering effect cannot be obtained, which is not preferable. When the fine particles are mixed with the transparent resin serving as a matrix, the concentration of the fine particles is [fine particles / (sum of the fine particles and the transparent resin)], preferably 1 to 50% by volume, and 5% by volume.
-30% by volume is more preferred.

The inorganic fine particles of the present invention may be subjected to a coating treatment on the surface as required. Although not limited, an organic compound or an inorganic compound containing a metal ion or the like can be preferably used. For example, a silane coupling agent, a titanium coupling agent, an aluminum-based coupling agent, or the like can be used.

In the present invention, as the alumina fine particles,
For example, Sumitomo Chemical Co., Ltd. Sumicorundum AA
04 (primary particle size 0.4 μm), AA05 (primary particle size 0.4 μm).
5 μm), AA07 (primary particle size 0.7 μm), AA1
(Primary particle size 1.0 μm), AA2 (primary particle size 2.0 μm)
m), AA4 (primary particle size 4.0 μm), AA10 (primary particle size 10.0 μm) and the like. Examples of titania fine particles include, for example, JP-A-7-187612 and JP-A-7-187613. And titania fine particles produced using the method described in (1).

In the present invention, the type of the inorganic fine particles dispersed in the transparent resin is the same.
Not limited to the type, two or more types of inorganic fine particles such as particles having different particle diameters and different types can be combined.
In the present invention, fine particles to be dispersed in the transparent resin,
Organic resin fine particles can be combined in addition to inorganic fine particles. Examples of such organic resin fine particles include fine particles of silicone resin, acrylic resin, polystyrene, polyethylene, polyurethane, and the like.

In the present invention, the thickness of the light scattering resin layer is 0.2
μm to 100 μm, preferably 0.5 μm
m or more and 50 μm or less. Further, in the light scattering resin layer of the present invention, the surface of the light scattering resin layer may have irregularities with a depth of 0.05 μm to 10 μm as needed.

In the present invention, the number average particle diameter of the inorganic fine particles is preferably from 0.4 μm to 20.0 μm, and more preferably from 0.4 μm to 4.0 μm.

In the light scattering layer of the present invention, the thickness of the light scattering resin layer in which the inorganic fine particles are dispersed is preferably 0.5 μm.
m or more and 50.0 μm or less, more preferably
It is 0.5 μm or more and 4.0 μm or less. Since the preferable minimum value of the particle size of the fine particles is 0.4 μm, it is not preferable that the particle size is less than 0.5 μm in consideration of the unevenness of the resin layer surface. On the other hand, if the thickness of the resin layer is too large, the light transmittance is undesirably reduced.

Next, a light scattering plate using the light scattering layer of the present invention and a liquid crystal display device having the same will be described in detail. First, the present invention, in a light scattering layer that scatters transmitted light by dispersing the inorganic fine particles in a transparent resin, a light scattering resin layer in which the inorganic particles are dispersed,
The present invention relates to a light scattering plate having the light scattering resin layer formed on the surface of the scattering plate or in the scattering plate, and a liquid crystal display device using the same. The scattering plate refers to one having the scattering resin layer formed on its surface or one having the scattering resin layer itself functioning as a light scattering plate.

In the light scattering plate of the present invention, when the light scattering resin layer is formed on the surface of the transparent substrate, the transparent substrate may be any transparent material, and the material such as glass and polymer film is not particularly limited. . A combination with various liquid crystal display device-related members such as a polarizing film, a retardation film, a brightness enhancement film, and a 波長 wavelength plate, and application to the inside or upper and lower surfaces thereof may be used. A polarizing film or the like on which a diffraction grating or the like is laminated may be used as the substrate.

In this case, as the transparent resin serving as the matrix, for example, an epoxy resin, an acrylic resin, an acrylic epoxy resin, a polyester resin, a polyamide resin, a urethane resin, a polyimide resin, or a copolymer resin thereof can be used. It is also possible to use epoxy resin to which melamine resin is added. Also,
These resins may be ultraviolet curable resins, thermosetting resins, electron beam curable resins, or resins using these curing methods in combination.

As a method for dispersing the inorganic fine particles in these transparent resins, fine particles are added to a transparent resin dissolved in a solvent, and an ultrasonic dispersion method is applied to the mixed solution.
A stirring defoaming mixer, a ball mill, a jet mill, or the like can be used. As a method for forming the light scattering resin layer, for example, an offset printing method, a screen printing method, a roll coating method, a gravure coating method, a bar coating method, a spin coating method, a curtain coating method, a spray coating method, or the like can be used. .

In the light scattering plate of the present invention, when the scattering resin layer itself functions as a light scattering plate, the fine particles are dispersed in a transparent resin and formed into a plate or film to form the light scattering plate. Get.

In the light-scattering plate of the present invention, as the transparent resin serving as a matrix, changes in optical properties and shapes occur when the light-scattering plate is used at a high temperature or at the temperature of the bonding step with a liquid crystal cell. Polymers having no glass are preferred, and thermoplastic engineering polymers having a high glass transition temperature to some extent, or polymers having a plasticizer added to them are preferably polymers having a somewhat high flow temperature.

The glass transition temperature of the matrix polymer
The softening temperature is within the temperature range where the liquid crystal display is used.
To prevent deformation such as changes in chemical characteristics and film shrinkage.
The lower limit is determined, and it is stretched while heating when making it into a retardation plate
If the glass transition temperature is too high, industrial
Is not preferable, the upper limit is determined. Matric
Of glass transition temperature or softening temperature required for
As a range, 50-250 degreeC is preferable and 70-23.
0 ° C. is more preferred. Preferred height that satisfies these conditions
Molecules include polycarbonate polymers, polyarylene
Salt polymer, polystyrene polymer, polyvinyl alcohol
Cole polymer, polyolefin polymer, polyvinyl chloride
Nyl polymer, polyester polymer, polysulfone
Polymer, polyether sulfone polymer, cellulose acetate
Glucose, cellulose acetate, ethylene vinyl alcohol
Polymers and the like are exemplified.
Examples include polystyrene, polyarylate, and cellulose acetate.
Is shown.

The thickness of the light-scattering resin layer in the light-scattering plate of the present invention and the liquid crystal display device having the same is preferably 0.1 mm.
It is 5 μm or more and 50.0 μm or less, and more preferably 10.0 μm or more and 50.0 μm or less. If the thickness is too small, the mechanical strength is adversely affected. If the thickness is too large, the evaporation rate of the solvent when the film is formed by the solvent casting method is slowed, and the productivity is deteriorated.

In the present invention, a method for forming a light scattering plate when the scattering layer itself functions as a light scattering plate will be described. As a method for dispersing the inorganic fine particles in the polymer, fine particles are added to a polymer solution dissolved in a solvent, and the mixed solution is subjected to an ultrasonic dispersion method, a stirring and defoaming mixer, a ball mill, a jet mill. Etc. can be used. Further, the inorganic fine particles of the present invention, if necessary,
A coating treatment may be applied to the surface as described above.

The method of forming the light scattering plate comprising the polymer and fine particles serving as the matrix described above includes a solvent casting method for casting a dispersion solution, an extrusion molding method, a calendering method, and the like.
A press molding method and the like are exemplified, and among them, a solvent casting method having excellent film thickness accuracy is preferable. By incorporating the thus formed light scattering plate into a component of the liquid crystal display device, the scattering characteristics are improved while maintaining high light transmittance, and the display quality can be improved.

Next, the color filter for a liquid crystal display device provided with the light scattering resin layer of the present invention and the use of the liquid crystal display device using the same will be described in detail. The present invention relates to a color filter having a function of scattering the transmitted light by forming the light scattering resin layer on or in a color filter layer, and a liquid crystal display device using the same.

A method for forming a light scattering resin layer on a color filter substrate according to the present invention will be described. The color filter having the light-scattering resin layer of the present invention is obtained by dispersing fine particles in a transparent resin such as an overcoat resin or a color resist, and dispersing the fine particles on one or both surfaces of a transparent substrate, or on a color filter layer or a color filter layer. Obtained by coating inside. In the present invention, a transparent substrate refers to a glass substrate or the like serving as a substrate of a color filter layer, and a color filter layer refers to a respective dye layer or the like for coloring transmitted light transmitted through the portion.

In the color filter of the present invention, when a light scattering resin layer is formed, the transparent resin serving as a matrix includes, for example, epoxy resin, acrylic resin, acrylic epoxy resin, polyester resin, polyamide resin, urethane resin, and polyimide resin. Alternatively, these copolymer resins can be used. It is also possible to use epoxy resin to which melamine resin is added. Also,
These resins may be ultraviolet curable resins, thermosetting resins, electron beam curable resins, or resins using these curing methods in combination.

As a method of dispersing the inorganic fine particles in these transparent resins, fine particles are added to a transparent resin dissolved in a solvent, and the mixed solution is subjected to an ultrasonic dispersion method.
A stirring defoaming mixer, a ball mill, a jet mill, or the like can be used. As the color filter layer, a known color filter layer can be applied. For example, a dyeing color filter in which a resin is dyed with a dye, a photosensitive resin in which an organic pigment is dispersed and a pigment dispersion type color filter formed by a photolithography process, printing formed by an offset printing method, a letterpress printing method, or a flexographic printing method. Color filter or the like.

As a method of forming the light scattering resin layer, for example, an offset printing method, a screen printing method, a roll coating method, a gravure coating method, a bar coating method, a spin coating method, a curtain coating method, a spray coating method, or the like is used. be able to. By incorporating a color filter having the light-scattering resin layer formed in this way into a component of a liquid crystal display device, while maintaining high light transmittance,
The scattering characteristics are improved, and the display quality can be improved.

[0032]

Next, examples of the present invention will be described, but the present invention is not limited to these examples. Various measurement methods in the present invention are shown below. Measurement of number average particle diameter of primary particle system Scanning electron microscope (SEM, manufactured by JEOL Ltd .: T-3)
00), a photograph of the powder particles was taken, 50 to 100 particles were selected from the photograph, image analysis was performed, and the average value was determined.

Measurement of D10 and D90 (Measurement of Weight Cumulative Particle Size Distribution) Measured by a laser diffraction scattering method using a master sizer (manufactured by Maru Balloon Co., Ltd.). The alumina slurry prepared for the measurement is based on 2.5 g of alumina powder.
0.5 mass% aqueous solution of sodium hexametaphosphate
5 g was added, and the mixed solution was adjusted by irradiating an ultrasonic wave with a homogenizer for 2 minutes.

Measurement of D / H ratio Scanning electron microscope (SEM, manufactured by JEOL Ltd .: T-3)
00), a photograph of the powder particles was taken, 5 to 10 particles were selected from the photograph, image analysis was performed, and the average value was determined.

Measurement of Haze (Haze Value) and Total Light Transmittance Haze Computer (manufactured by Suga Test Instruments Co., Ltd .: HGM-
2DP) was used to measure haze (haze value) and total light transmittance.

Evaluation of scattering characteristics Light emitted from a fiber type light source (SPH-100N, manufactured by Chuo Seiki Co., Ltd.) is collimated by a lens and irradiated to a sample to be measured. The sample is inserted in a direction in which the sample surface is perpendicular to the optical axis. The intensity of light transmitted through the sample and light scattered by the sample was measured with an optical sensor and an optical power meter. The angle distribution of the scattered light was measured by rotating the optical sensor unit horizontally from -90 ° C to 90 ° C around the optical axis with respect to the optical axis. The comparison of the scattering intensity is as follows: I _{0 is} the light intensity when no sample is placed, and I is the scattering intensity ratio when the intensity of light scattered in a certain angle direction by the sample is I _R :

[0037]

## EQU1 ## I _R = I / I ₀

[0038]

Polarization analysis UV-visible spectrophotometer (manufactured by Shimadzu Corporation: MPC-220)
The polarization analysis was performed using (0) to calculate the degree of depolarization from the reference polarizing plate (hereinafter, the degree of polarization). A sheet having no polarization shift with respect to a reference polarizing plate is defined as 100%. The wavelength used was 400 nm to 700 nm.

Example 1 In order to perform silane coupling treatment on the surface of alumina fine particles, alumina fine particles were added to a silane coupling agent, dispersed by ultrasonic waves for 2 hours, and then vacuum dried. As a silane coupling agent, KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd. was used, and as fine alumina particles, Sumikotorandom AA1 (number average particle size: 1.0 μm) manufactured by Sumitomo Chemical Co., Ltd. was used. Subsequently, a one-component type overcoat liquid serving as a matrix (V-Nippon Steel Chemical Co., Ltd.)
(259EX88-078X) 80% by volume and 20% by volume of alumina fine particles subjected to silane coupling treatment were mixed and dispersed by ultrasonic waves for 2 hours. This was spin-coated (840 rpm; 10 seconds) on a glass substrate, and prebaked at 100 ° C. for 10 minutes using a clean oven.
Post-baking was performed at 30 ° C. for 20 minutes to form a light-scattering resin layer having a thickness of 1.5 μm. Against this way light scattering resin layer formed, the scattering characteristic measurement, and haze measurement was subjected to a total light transmittance measurement, the scattering in the scattering angle 30 ° intensity ratio I _R = 0.033, the haze; 81.
2. A value of 97% was obtained for the total light transmittance. As a result of an ellipsometry, the degree of polarization was 99.98%. Details are shown in Table 1. Further, as a result of microscopic observation of the light scattering resin layer, almost no aggregation was observed, and it was visually confirmed that the light scattering resin layer was substantially uniformly dispersed. What is shown as "good" in the dispersibility of Table 1 shows that almost no coagulation is observed and the dispersion is almost uniform.

Example 2 A light-scattering resin layer was formed on a glass substrate in the same manner as in Example 1, except that Sumikotorandom AA07 (number average particle size: 0.7 μm) manufactured by Sumitomo Chemical Co., Ltd. was used as the alumina fine particles. Was formed. In contrast, the scattering characteristic measurement, and haze measurement was subjected to a total light transmittance measurement, the scattering in the scattering angle 30 ° intensity ratio I _R = 0.020, the haze; 54.3, the total light transmittance; A value of 96% was obtained. As a result of performing ellipsometry, the degree of polarization was 99.96%. Details are shown in Table 1. Further, as a result of microscopic observation of the light scattering resin layer, almost no aggregation was observed, and it was visually confirmed that the light scattering resin layer was substantially uniformly dispersed.

Example 3 By forming the light scattering resin layer formed in Example 1 on a color filter and using it in combination with a liquid crystal display cell, the viewing angle, the contrast ratio and the like are improved, and the visibility is improved. Excellent display cells can be obtained.

Example 4 By forming the light scattering resin layer formed in Example 2 on a color filter and using it in combination with a liquid crystal display cell, the viewing angle, the contrast ratio and the like are improved, and the visibility is improved. Excellent display cells can be obtained.

Example 5 80% by mass of a polycarbonate resin and 20% by mass of methylene chloride are dissolved and mixed. 80% by volume of this mixed solution and 20% by volume of alumina microparticles (Sumicorundum AA5 manufactured by Sumitomo Chemical Co., Ltd.) are mixed and dispersed by ultrasonic waves. The light dispersion film is obtained by casting the obtained dispersion solution on a glass plate and drying the solvent. By using the obtained light-diffusing film bonded to a liquid crystal display cell, the viewing angle, contrast ratio, etc. are improved,
A display cell with excellent visibility can be obtained.

Comparative Example 1 The procedure of Example 1 was repeated, except that alumina (number average particle diameter: 0.85 μm) produced by a hydrolysis method using an aluminum organometallic compound was used as the alumina fine particles.
A light scattering resin layer was formed on a glass substrate. In contrast, the scattering characteristic measurement, and haze measurement was subjected to a total light transmittance measurement, the scattering in the scattering angle 30 ° intensity ratio I _R = 0.016, the haze; 40.5, the total light transmittance; A value of 96% was obtained. Details are shown in Table 1. As a result of the ellipsometry, the degree of polarization was 99.88%.
Details are shown in Table 1. Further, as a result of microscopic observation of the light-scattering resin layer, many agglomerated portions were observed, and it was visually confirmed that a favorable dispersion state was not obtained. In the dispersibility shown in Table 1, "poor" indicates that many agglomerated portions were observed, indicating that a good dispersion state was not obtained.

Comparative Example 2 A glass substrate was prepared in the same manner as in Example 1 except that alumina (number average particle diameter: 0.65 μm) produced by a hydrolysis method using an aluminum organometallic compound was used as the alumina fine particles. To form a light scattering resin layer. In contrast, the scattering characteristic measurement, and haze measurement was subjected to a total light transmittance measurement, the scattering in the scattering angle 30 ° intensity ratio I _R = 0.011, the haze; 34.0, the total light transmittance; A value of 94% was obtained. Details are shown in Table 1. As a result of performing ellipsometry, the degree of polarization was 99.87%.
Details are shown in Table 1. Further, as a result of microscopic observation of the light-scattering resin layer, many agglomerated portions were observed, and it was visually confirmed that a favorable dispersion state was not obtained.

[0047]

[Table 1]

Comparative Example 3 A light diffusing film was formed in the same manner as in Example 1 except that the step of subjecting alumina fine particles to silane coupling treatment was omitted. On the other hand, as a result of microscopic observation of the light diffusion film, some agglomerated portions were observed, and it was visually recognized that a better dispersion state was not obtained as compared with Example 1.

[0049]

According to the present invention, the dispersibility of fine particles in a transparent resin serving as a matrix is high,
It is possible to obtain a light scattering layer having improved forward scattering characteristics and excellent light transmittance. Further, by incorporating a light scattering plate, or a light diffusion film, and further a color filter provided with a light scattering layer, into components of the liquid crystal display device, while maintaining high light transmittance, the scattering characteristics are improved, Visibility can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a liquid crystal display device in which a light scattering plate according to the present invention is incorporated in a component.

FIG. 2 is an explanatory view showing an example of a liquid crystal display device in which a scattering function-added color filter of the present invention is incorporated in a component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Polarizer 3r Red color filter 3g Green color filter 3b Blue color filter 4 Liquid crystal layer 5 Overcoat layer 6 Transparent electrode 7 Light scattering plate

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) G02B 5/30 G02B 5/30 4J002 G02F 1/1335 G02F 1/1335 505 505 (72) Inventor Koichi Fujisawa Tsukuba, Ibaraki Kitahara 6 Sumitomo Chemical Co., Ltd.F-term (reference) CA26 DA02 DA11 FA02 4J002 AB021 BB032 BC031 BC032 BD031 BE011 BE031 BG051 BG052 CD001 CF001 CF161 CG011 CK021 CK022 CM041 CN031 CP032 DC006 DE096 DE136 DE146 FA082 FB086 FB096 FB166 GP00

Claims (13)

[Claims] 1. Polyhedral fine particles having substantially no crushed surface having different refractive indices, wherein the L / S ratio is 2.0 when the long axis length of the fine particles is L and the short axis length is S. The fine particles having a number average particle diameter of 0.1 μm or more and 2
0.010 μm or less, and the particle diameters of 10% and 90% cumulative from the fine particle side of the cumulative particle size distribution are D10 and D90, respectively.
A light scattering layer characterized by having a resin layer in which inorganic fine particles having a particle size distribution of D90 / D10 of 7 or less when dispersed are dispersed in a transparent resin to thereby scatter transmitted light. 2. An inorganic fine particle is a polyhedral fine particle having substantially no crushed surface, wherein the maximum particle diameter parallel to the hexagonal lattice surface of α-alumina which is a hexagonal close-packed lattice is D, and the hexagonal close-packed lattice surface is When the particle diameter perpendicular to the particle diameter is H, the D / H ratio is 0.5
Consisting of α-alumina fine particles of not less than 2.0 and
Number average particle size of alumina fine particles is 0.1 μm or more and 20.0
μm or less, and the cumulative 10
The light-scattering layer according to claim 1, wherein D90 / D10 has a particle size distribution of 7 or less, where D10 and D90 are the particle diameters of 90% and 90%, respectively. 3. The light scattering layer according to claim 1, wherein the inorganic fine particles have been subjected to a surface coating treatment. 4. The light-scattering layer according to claim 3, wherein the surface of the inorganic fine particles is coated with an organic compound containing a metal ion or an inorganic compound containing a metal ion. 5. The light-scattering layer according to claim 4, wherein the organic compound containing a metal ion or the inorganic compound containing a metal ion is a silane coupling agent, a titanium coupling agent or an aluminum-based coupling agent. 6. The light-scattering layer according to claim 1, wherein organic resin fine particles are added in addition to the inorganic fine particles. 7. The light-scattering layer according to claim 1, wherein the thickness of the light-scattering resin layer in which inorganic fine particles are dispersed in a transparent resin is in the range of 0.2 μm to 100 μm. 8. The light-scattering layer according to claim 1, wherein the light-scattering resin layer in which the inorganic particles are dispersed is:
A light-scattering plate characterized by being used on the surface of the scattering plate or in the scattering plate. 9. A polarizing plate, an elliptically polarizing plate or a retardation plate comprising the light scattering plate according to claim 8. 10. A liquid crystal display device comprising the light scattering plate according to claim 8 on at least one of the outside and the inside of a liquid crystal cell. 11. A liquid crystal display device comprising the polarizing plate, the elliptically polarizing plate or the retardation plate according to claim 9 on at least one side outside the liquid crystal cell. 12. The light-scattering layer according to claim 1, wherein the light-scattering resin layer in which the inorganic particles are dispersed is provided on one or both sides of a transparent substrate or on a color filter layer. Color filters for liquid crystal display devices. 13. A liquid crystal display device comprising the color filter for a liquid crystal display device according to claim 12 as a component thereof.