JP2001108805A - Filler lens and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filler lens which is superior in uniform light diffusivity when compared with the conventional light diffuser and a method of manufacturing the same. SOLUTION: This filler lens is constituted by laminating a binder layer 2 having a gel fraction of >=60% directly or via another layer on a substrate 1. The filler lens has a filler layer 3A embedded in the surface layer of the binder layer in the state of projecting from the surface layer of the binder layer. This filler layer 3A is so formed that the ratio of the projection of the fillers 3 attains >=50%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to, for example, LCDs,
The present invention relates to a filler lens which is suitably used for displays such as EL and FED, and which exhibits excellent effects of preventing uneven brightness, improving contrast, and widening a viewing angle of these displays, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, displays such as LCDs, ELs, and FEDs have been remarkably developed. In particular, LCDs have become widespread in all fields such as notebook computers and portable terminals, and expectations for the future are great. This LCD is roughly classified into a reflection type and a transmission type according to a method of taking in light for illuminating a liquid crystal panel. In the reflection type, a reflection plate with a high reflectance aluminum film or the like attached or deposited on the back of the liquid crystal panel is arranged,
External light incident from the display surface side is reflected by a reflector to illuminate a liquid crystal panel to obtain a liquid crystal image. On the other hand, the transmission type is a method in which a liquid crystal panel is illuminated by a backlight unit arranged on the back of the liquid crystal panel. In the case of the reflective type, a medium that diffuses light is interposed between the liquid crystal panel and the reflective plate, or mat processing (surface roughening) is performed to prevent the background color of aluminum from appearing and deteriorating the contrast. The background color is made closer to a paper white color by diffusing light using, for example, a film obtained by evaporating aluminum on a mat surface of a film that has been treated.
In addition, a backlight unit of the transmission type generally includes a light source such as an acrylic light guide plate having a cold cathode tube and a light diffusion plate for diffusing light from the light source, and a uniform planar light passes through the liquid crystal panel. It is configured to illuminate.

As described above, a light-diffusing medium (hereinafter, referred to as a light-diffusing body) is generally used in both the reflection type and the transmission type. As the light diffuser, for example, a material in which a binder resin in which a light-diffusing filler is dispersed is laminated on one surface of a transparent resin film may be used. Such a conventional light diffuser has been manufactured by a method in which a filler is dispersed in a solution obtained by mixing a solvent with a binder resin to form a coating, and the coating is applied on a film by a spray or a coater. FIG. 15 schematically shows a light diffuser obtained by such a manufacturing method. A light diffusion layer in which a filler 23 is dispersed in a binder resin 22 is formed on a film 21.

[0004]

The above-mentioned conventional light diffuser has a light diffusing property, but has a problem in that the light diffusing property is low. The reason for this is that the filler is completely embedded in the binder layer, the filler overlaps in the thickness direction of the light diffusion layer and is in a multi-layer state, and as a result, diffused light from the configuration cancels out each other, Light transmittance was attenuated (light energy was lost). Further, in the conventional light diffuser described above, there is a problem in stable productivity from the viewpoint that a problem such as poor dispersion of a filler, agglomeration, precipitation, and the like are apt to occur at the time of manufacture, and furthermore, optical characteristics are easily changed by a film thickness. Was.

Therefore, the present inventors embed a filler in a single layer so that a part of the filler protrudes from the binder layer, and if the protruded filler is formed into a fine lens, the light diffusion property is high and the uniformity is high. I think that a light diffuser, that is, a light diffuser with a high paper-white property, can be obtained.
The following manufacturing method was tried. That is, first, a binder layer is formed on a film, then a filler is attached to the binder layer, and then the filler is embedded in the binder layer using a pressure roller. In this method, the pressure balance of the pressure roller is important, and the pressure difference occurs at both ends and the center due to variations in film thickness, bending of the pressure roller, etc., resulting in a difference in the filling depth of the filler. I understood. This was particularly noticeable when processing was performed on a large area. Further, when embedding a filler having a volume average particle size of 15 μm or less, the pressure transmitted from the pressure roller to each filler is dispersed and the pressure becomes insufficient, so that the filler cannot be sufficiently embedded in the binder layer. Had. Furthermore, in this production method, the filling density of the filler is low and non-uniform, resulting in a light diffuser having partially different light diffusivity, and cannot be used practically. FIG. 16 is an optical microscope photograph of a plane of a light diffuser manufactured using a spherical filler having a volume average particle diameter of 4.5 μm by the above manufacturing method using a pressure roller, using a 10 × objective lens. . Since the filling density and the embedded depth of the filler are not uniform, the light diffusivity is not uniform. And
A light diffuser having a structure in which a binder layer 2 made of a binder resin is formed on a film-like substrate 1 as shown in FIG. 17 and a filler 3 partially protrudes has also been proposed. However, when the light diffuser as shown in FIG. 17, that is, the light diffuser in which the proportion of the filler protruding from the binder layer is less than 50%, the light diffusion performance is insufficient when used in a reflective liquid crystal display. However, there has been a problem that the background color of aluminum appears and the contrast deteriorates.

Accordingly, an object of the present invention is to provide a filler lens having a higher and more uniform light diffusivity as compared with a conventional light diffuser, and a method for producing the same.

[0007]

SUMMARY OF THE INVENTION The filler lens of the present invention has a gel fraction of 6 on a substrate directly or through another layer.
It is characterized in that a binder layer of 0% or more is laminated, and a filler layer embedded in a surface layer of the binder layer so as to protrude when the percentage of filler protrusion is 50% or more. Note that a coating or another layer that improves light diffusion may be formed on the surface of the filler layer.

[0008] The filler layer of the present invention is a single layer and is formed on the surface of the binder layer so that the proportion of filler protrusion is 50% or more, thereby improving light diffusion and uniformity. Have improved. That is, the inventor paid attention to the ratio of the protrusion of the filler from the surface of the binder layer in order to further improve the optical characteristics of the filler lens. In the filler lens initially developed by the present inventor, as shown in FIG. 17, the ratio of the protrusion of the filler 3 was less than 50%. The inventor of the present invention has developed a filler lens having a large protrusion ratio of the filler 3 as shown in FIG. That is, FIG. 1 is a cross-sectional view schematically showing one example of the filler lens of the present invention. In this filler lens L, a binder layer 2 is directly laminated on a base 1, a large number of fillers 3 are provided on the surface layer of the binder layer 2, and the proportion of filler protrusion on the surface of the binder layer 2 is 50% or more. The filler layer 3A is formed by being buried so as to have a high density in the plane direction in a protruding state. When the light diffusivity and uniformity of such a filler lens were investigated, it was found that those shown in FIG. 1 had improved optical characteristics as compared with those shown in FIG. Was completed. The term “single layer” as used in the present invention means that fillers projecting from the surface of the binder layer are formed without overlapping portions.

[0009] The binder layer has a gel fraction of 60% or more, more preferably 70% or more, and most preferably 80% or more. In the binder layer having a gel fraction of less than 60%, the filler is deeply embedded because it is soft, and the light diffusion function of the filler cannot be sufficiently exhibited. In addition, in a binder layer having a gel fraction of less than 60%, environmental resistance (reliability) deteriorates. In particular, in a high-temperature and high-humidity environment, the binder layer is softened, and the filler sinks deeply into the binder layer, so that the light diffusion property is reduced. Therefore, in the production method of the present invention,
The step of embedding a filler is performed after the binder layer contains a resin having a cross-linking point and a curing agent and is sufficiently cross-linked to a gel fraction of 60% or more.

The "gel fraction" in the present invention can be measured as follows. The weight A of a filler lens having an arbitrary size is measured. The binder layer of the filler lens is swollen with a solvent such as alcohol (eg, methanol) which does not attack the base of the filler lens, and then the binder layer is separated from the base. (As a method of separating, for example, a spatula may be used.) The weight B of the substrate from which the binder layer has been separated is measured, and AB is calculated to obtain the weight C of the binder layer. The binding layer separated from the substrate is immersed in acetone at room temperature and normal humidity for 24 hours, and then stirred with an ultrasonic disperser.
In the acetone after stirring, the gel content of the binder layer and the filler contained in the binder layer are mixed. In order to separate the filler and the gel component of the binder layer in acetone, a liquid having a specific gravity (such as chloroform) that separates the gel component and the filler is added to acetone to precipitate the filler, while the gel component is suspended. Let it. Next, the gel component suspended in acetone is filtered and dried, and its weight D is measured. On the other hand, the filler in the precipitated acetone is also filtered and dried, and its weight E is measured. The “gel fraction” referred to in the present invention can be obtained from the obtained weights by the following formula. Gel fraction (%) = D / (CE) × 100

[0011] The ratio of the protrusion of the filler from the binder layer must be 50% or more in order to prevent the filler from peeling from the binder layer and to surely exhibit light diffusion. . In addition, the proportion of the protrusion of the filler in the present invention is preferably 50 to 90%, more preferably 55 to 8%.
0%, most preferably 60-80%. The light diffusion performance of the filler is greatly affected by the ratio of the protrusion of the filler, and if it is less than 50%, the diffusion performance is significantly reduced. on the other hand,
If the protruding ratio exceeds 90%, the filler is liable to be detached from the binder layer in a step of removing the surplus filler, which is not preferable.

The term "protrusion ratio of filler" in the present invention can be obtained by analyzing a cross-sectional photograph of the filler layer, and is an average value of the protrusion ratio of arbitrary 30 fillers. That is, FIG. 2 is a schematic view of a cross-sectional photograph in which the filler 3 is embedded so as to protrude from the laminated binder layer 2 on the base 1. In order to obtain the ratio of the protrusion of the filler, a straight line is drawn on the interfaces a and b between the filler 3 and the binder layer 2 in FIG. 2, and an intersection d between the center line c of the filler 3 and the straight line is obtained. Next, the length Y from the tangent to the intersection d of the filler 3 is obtained, and the ratio of the protrusion of one filler can be obtained from the diameter X of the filler 3 by the following equation. The ratio of the protrusion of one filler (%) = Y / X × 100 After calculating the ratio of the protrusion of the 30 fillers in this manner, the “proportion of the protrusion of the filler” in the present invention is calculated from the average value. You can ask.

<Specific Examples of Materials> Next, suitable materials for use in the filler lens of the present invention will be described. (1) Substrate As the substrate of the present invention, a known transparent film can be used. Specifically, polyethylene terephthalate (PET), polyethylene naphthalate (PE)
N), various resin films composed of triacetyl cellulose (TAC), polyalate, polyimide, polyether, polycarbonate, polysulfone, polyethersulfone, cellophane, aromatic polyamide, polyethylene, polypropylene, polyvinyl alcohol and the like can be suitably used. it can. The substrate of the present invention is not limited to such a film, but may be a hard plate made of the above resin, or a sheet member made of a glass material such as quartz glass or soda glass other than the resin plate. The substrate may be a non-transparent material as long as light is transmitted therethrough. However, when used for a liquid crystal display or the like, the refractive index (JIS K-7142) should be 1.45 to 1.45 to match the refractive index.
A transparent substrate in the range of 1.55 is desirable. Specific examples include acrylic resin films such as triacetyl cellulose (TAC) and polymethyl methacrylate. The higher the transparency of these transparent substrates, the better, but the total light transmittance (JIS C-6714) is 85% or more, more preferably 90% or more, and the haze (JIS K7105) is 3.0. Or less, more preferably 1.0 or less, still more preferably 0.5 or less. When the transparent substrate is used for a small and lightweight liquid crystal display, the transparent substrate is more preferably a film. Regarding the thickness of the transparent substrate, it is desirable to be thin from the viewpoint of weight reduction. However, in consideration of the productivity, it is preferable to use a transparent substrate having a thickness of 1 μm to 5 mm. As the substrate, a filler lens can be formed directly or via another layer on the other side of the film on which a lens having a light collecting or diffusing property is formed on one side.

(2) Binder layer The binder layer of the present invention is preferably a pressure-sensitive adhesive layer obtained by coating a pressure-sensitive adhesive on the substrate. Examples of the pressure-sensitive adhesive include resin-based pressure-sensitive adhesives such as polyurethane resins, silicone resins, and acrylic resins. These may be used alone or in combination of two or more. In particular, acrylic resin is water resistant,
It is preferable because it is excellent in heat resistance, light resistance, etc., has good adhesive strength and transparency, and when it is used for a liquid crystal display, the refractive index can be easily adjusted to conform to it. Acrylic adhesives include acrylic acid and its esters,
Homopolymers or copolymers of acrylic monomers such as methacrylic acid and its esters, acrylamide and acrylonitrile, and further, at least one of the above acrylic monomers and an aromatic vinyl monomer such as vinyl acetate, maleic anhydride, and styrene And copolymers thereof. In particular, ethylene acrylate, butyl acrylate, 2-ethylhexyl acrylate and other main monomers that exhibit adhesiveness, vinyl acetate, acrylonitrile, acrylamide, styrene, methacrylate, methyl acrylate, and other monomers that serve as cohesive components, and further improve adhesive strength. A functional group containing methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, maleic anhydride, etc. A copolymer composed of monomers, having a Tg (glass transition point) in the range of -60 to -15 ° C and a weight average molecular weight of 20
Those in the range of 10,000 to 1.3 million are preferred. As the curing agent, for example, a crosslinking agent such as a metal chelate type, an isocyanate type, or an epoxy type may be used as a curing agent.
These are used alone or in combination of two or more. It is practically preferable to use these compounds so that the gel fraction after curing becomes 60% or more. Further, as the pressure-sensitive adhesive, a UV-curable adhesive to which a photopolymerizable monomer, oligomer, polymer and photopolymerization initiator are added may be used.

(3) Filler The filler of the present invention includes inorganic fillers such as silica, glass and alumina, acrylic resins, polystyrene resins, polyethylene resins, epoxy resins, silicone resins, polyvinylidene fluoride, teflon, divinylbenzene, and phenol. Resin, urethane resin, cellulose acetate,
Organic fillers such as nylon, cellulose, benzoguaminan, and melamine can be used, but organic fillers are preferable in terms of light transmittance and adhesion with the binder layer,
Further, acrylic beads and silicone beads are particularly preferable in terms of light resistance. Inorganic fillers such as silica and glass are not preferable because they have poor adhesion to the binder layer, and the fillers are liable to fall off during the filler embedding step and the washing step, so that the fillers are easily removed.

In the filler layer composed of a large number of such fillers, it is preferable that the individual fillers are uniformly arranged at high density in the plane direction. In order to obtain such a high-density filler layer, a filler having a volume average particle diameter of about 1 to 50 μm can be used. It is more preferably from 2 to 15 μm, most preferably from 2 to 10 μm. In this case, if the particle diameter of the filler is smaller than 2 μm, the diffused light interferes with each other to give a rainbow color, and the color contrast is undesirably reduced. In the case of a filler larger than 15 μm, the edge portion of the liquid crystal image is undesirably blurred. Further, in order to obtain a high and uniform light diffusing property, the particle size distribution is preferably narrow to 0.8 to 1.0.
Is preferable, and the best effect can be obtained at the time of monodispersion (when the particle size distribution is 1.0). The narrower the particle size distribution, the more evenly the impact force from the pressurized medium is transmitted to the filler, so that the depth of the filler embedded in the binder layer is likely to be uniform, and the filling density of the filler in the surface direction is also uniform. Easy to be.

In the present invention, "volume average particle size" is defined as follows, and "particle size distribution" is defined by the following equation. Particle diameter distribution = number average particle diameter / volume average particle diameter ・ Number average particle diameter = average value obtained by measuring diameters of 100 fillers randomly extracted from a photograph of a filler lens. -Volume average particle size = First, from the photograph of the filler lens,
The diameter of 100 randomly selected fillers is measured. From the diameter of the obtained filler, the volume of each filler is determined by regarding the filler as a true sphere. Next, the volume of each filler is accumulated to calculate the total volume of 100 fillers. Thereafter, the volume is accumulated in the order of the volume from the smallest volume filler to the largest volume filler among the 100 fillers, and the diameter of the particles whose accumulated volume becomes 50% of the total volume. At this time, when the filler particles are not true spheres, the longest diameter is defined as the diameter of the filler. In this specification, the filler lens is a digital microscope manufactured by KEYENCE CORPORATION (trade name: VH-
6300) using a transmitted light image photograph.

In order to obtain uniform light diffusion performance, the filler is desirably spherical, and its roundness is 8
It is preferably at least 0%, more preferably at least 90%. At this time, the spherical filler also has an effect that the embedded depth hardly varies. In the present invention, “roundness” is defined by the following equation. Roundness (%) = (4πF / G ² ) × 100 F: Projected area of filler G: Perimeter of filler This roundness can be obtained, for example, by photographing the filler with a transmission electron microscope and obtaining a projected image. Can be calculated from the above F and G obtained by performing image analysis using an image analysis apparatus (for example, trade name: EXECLII manufactured by Nippon Avionics Co., Ltd.). As is apparent from the above equation, the roundness is close to 100% when the filler is close to a true sphere, and is smaller when the filler is irregular. In the present invention, the average value measured for 10 fillers is defined as roundness. When the refractive index of the filler is in the range of 1.42 to 1.55,
It is preferable because high light transmittance can be obtained.

(4) Other Layers Between the base and the binding layer constituting the present invention, as another layer, an adjusting layer for adjusting the refractive index and transmittance of light, or the base and the binding layer May be provided with an adhesive layer or the like for firmly adhering.

Next, the method for producing a filler lens according to the present invention is a preferred production method for producing a filler lens having the above-described structure. A step of forming a binder layer of a pressure-sensitive adhesive containing a resin and a curing agent on the substrate directly or via another layer; a step of curing the binder layer to increase the gel fraction to 60% or more; Adhering the filler onto the binder layer; embedding the filler into the binder layer with a pressurized medium so that the percentage of filler protrusion becomes 50% or more; adhering to the laminate obtained in the step Removing the surplus filler that has been obtained. At this time, a drying step of applying heat or the like may be added after the step. By applying heat or humidity, the binder layer and the filler become familiar and the light transmittance is improved, which is preferable. At this time, humidity can be added as needed.

<Specific Example of Manufacturing Method> Next, a specific example of the manufacturing method of the filler lens of the present invention will be described. “Step 1: Laminating a binder layer” The above pressure-sensitive adhesive is directly or through another layer on one or both sides of the above substrate, and is coated with an air doctor, a blade, a knife, a reverse, a transfer roll, or a gravure. Roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, electrodeposition coating, dip coating, die coating, etc., letterpress printing such as flexo printing, intaglio printing such as direct gravure printing, offset gravure printing It is applied by means of printing such as lithographic printing such as offset printing and stencil printing such as screen printing, and laminated as a binder layer. In particular, coating using a roll coater is preferable because a uniform layer thickness can be obtained. Although the thickness of the binder layer may be about 0.1 to 5 times the volume average particle diameter of the filler to be embedded,
When used for a liquid crystal display or the like, the volume average particle diameter of the filler is preferably about 0.1 to 2 times due to space restrictions. At this time, if the thickness of the binder layer is smaller than 0.1 times the volume average particle diameter of the filler, it is not preferable because the filler is likely to fall off in the step of removing the surplus filler.

[Step 2: Curing of the Binder Layer] After attaching a protective film such as a peelable PET film to the surface of the binder layer, it is left in an environment of about 20 to 80 ° C. for about 3 to 14 days to bond. The adhesive layer is cured to obtain a binder layer having a gel fraction of 60% or more. At this time, when a VU curing system is used as a curing system of the binder, the curing can be performed by UV irradiation.

[Step 3: Attachment of filler to binder layer] First, a filler is attached to the surface of the binder layer on the substrate. Examples of the method include a method in which a filler filled in a container is fluidized by vibration or fluidizing air, and a substrate is passed through the filler, or the filler is sprayed on a binder layer by spraying. By attaching the filler to the surface of the binder layer, defects such as filler removal are reduced, and at the same time, the pressurizing medium adheres to the binder layer in the step of embedding the filler into the binder layer by the subsequent pressurizing medium. It can also be prevented. Here, the filler only needs to be simply attached to the surface of the binder layer by the adhesive force of the binder layer.

[Step 4: Embedding Filler in Binder Layer] As a method of embedding the filler in the binder layer, the pressurizing medium is made into a granular material, and the pressurizing medium is vibrated so that the pressurizing medium is filled with the filler. To be embedded in the binder layer. According to this method, there is an advantage that the depth of filling of the filler is made uniform by the pressure medium hitting all over the minute area with a uniform force. Specifically, a pressurized medium is charged into an appropriate container, and the pressurized medium is vibrated together with the container. Into this, a substrate in which a filler is adhered to the surface of the binder layer is charged or passed. This gives an impact force to the filler. Then, the filler is hit by the pressurized medium and is embedded in the binder layer so that the percentage of protrusion of the filler becomes 50% or more. Since the pressurized medium can uniformly hit the filler with a small area, the filler can be embedded in the binder layer with a uniform embedding depth. At this time, if a mixed pressurized medium in which about 0.5 to 2.0 parts by weight of a filler is previously mixed with 100 parts by weight of the pressurized medium is used, the gap between the fillers attached to the surface of the binder layer in the previous step is reduced. Since it is possible to push other fillers by the impact force of the pressurized medium, the filler density can be made higher and uniform, which is preferable. By such a method, the filler is buried in the surface layer of the binding layer in a state where the burying depth is uniform so that the protrusion ratio becomes 50% or more, and a filler layer which is densely filled as a whole is formed. Is done. In addition, as the external force applied to bury the filler, rotation, falling, or the like may be employed in addition to vibration. In the case of rotation,
A rotating container, a container having stirring blades inside, or the like is used. When dropping is used as the external force, a V blender, a tumbler, or the like is used.

Here, a pressurized medium used for filling the filler will be exemplified. The pressurized medium is a granular material that acts to embed the binder layer by hitting the filler by vibration or the like as described above, and includes iron, carbon steel, alloy steel, copper and copper alloys, aluminum and aluminum alloys, and other materials. What consists of various metals and alloys, or Al ₂ O ₃ , SiO ₂ , Ti
Those made of ceramics such as O ₂ , ZrO ₂ , and SiC, and those made of glass, hard plastics, and the like are used. Hard rubber may be used as long as sufficient impact force can be given to the powder. In any case, the material of the pressurized medium is appropriately selected according to the material of the filler and the like. The shape is preferably close to a true sphere so that the pressure applied to the filler is uniform, and the whole particle distribution is preferably as narrow as possible.
The particle size of the pressurized medium is appropriately selected depending on the material of the filler and the depth of embedding of the filler.
About 2.0 mm is preferable.

[Step 5: Removal of Excessive Filler] After the step of embedding the filler in the binder layer, the excess filler is removed. The surplus filler is, for example, a filler that is incompletely embedded in the binder layer or a filler that is merely attached to the embedded filler by an interparticle force such as an electrostatic force or a van der Waals force. Such an excess filler can be removed by applying a fluid pressure to the filler layer by water washing, air blowing, or the like. At this time, when the volume average particle diameter of the filler is 2 to 15 μm, it is likely to be incomplete simply by removal with a fluid pressure such as air, so that an aqueous solution such as ion-exchanged water to which a surfactant or the like is added is used. It is preferable to perform ultrasonic cleaning or the like.

[0027]

Next, an embodiment of the present invention will be described.

[Production Example] <Polymerization Example of Acrylic Polymer a> n was placed in a flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet tube.
-94 parts by weight of butyl acrylate, 3 parts by weight of acrylic acid, 1 part by weight of 2-hydroxyacrylate, 0.3 parts by weight of benzoyl peroxide, 40 parts by weight of ethyl acetate, and 60 parts by weight of toluene are added. After introducing the flask into a nitrogen atmosphere, the flask was heated to 65 ° C. to perform a polymerization reaction for 10 hours, and the weight average molecular weight was about 1,000,000,
An acrylic polymer solution having a Tg of about −50 ° C. was obtained. Methyl isobutyl ketone was added to this acrylic polymer solution so that the solid content was 20% by weight, to obtain an acrylic polymer a.

Example 1 80 μm thick transparent substrate
m triacetyl cellulose (trade name: Fuji Tack UV
D80, manufactured by Fuji Photo Film Co., Ltd., refractive index 1.49). On one side of this film, isocyanate-based curing agent (trade name: 100 parts by weight of acrylic polymer a)
L-45, manufactured by Soken Chemical Co., Ltd.) and 0.4 parts by weight of an epoxy-based curing agent (trade name: E-5XM manufactured by Soken Chemical Co., Ltd.)
Parts by weight of the pressure-sensitive adhesive added thereto was applied with a reverse coater so that the thickness after drying was 5 μm, dried at 100 ° C. for 2 minutes, and then peeled PET film (trade name: 3811)
(Made by Lintec Co., Ltd.) and left in a constant temperature bath at 40 ° C. for 7 days to cure the binder layer. This film was cut into A5 plates, and the release PET film was peeled off.

The filler has a volume average particle diameter of 4.5.
Filler made of methyl silicone having a particle size distribution of 0.94, a refractive index of 1.43, and a roundness of 96% in μm (trade name:
Tospearl 145, manufactured by GE Toshiba Silicone Co.)
This filler was charged into a perforated plate container from which air was blown from the bottom. Thereafter, the container is vibrated, and the filler is fluidized by a synergistic effect of the vibration and the jet air.
The above-mentioned film having the binder layer formed on the surface thereof in the fluidized filler was passed through the film with appropriate time, and the filler was attached to the surface of the binder layer.

Next, a filler was buried in the surface layer of the binder layer to form a filler layer by the vibration device shown in FIG.
The container C of the vibrating device is made of a hard material such as a hard synthetic resin or a metal, and is formed in an arm shape having an opening c1 at an upper portion. The columnar part c which comes out and reaches the same height as the opening c1
3 are protruded. On the other hand, in the vibration mechanism V, a diaphragm f3 is mounted on the machine base F via coil springs f1 and f2, and a vertical axis f4 extending upward is protruded at the center of the upper surface of the diaphragm f3. Motor f
5 is fixed, and a weight f7 is attached to an output shaft f6 of the motor f5.
Are eccentrically mounted. Container C
Is set by fixing the upper end of the columnar portion c3 to the upper end of the vertical axis f4 while being placed on the diaphragm f3,
When the motor f5 is driven to rotate the weight f7, vibration is applied.

3 kg of spherical zirconia spheres having a particle diameter of 0.5 mm were charged as a pressurizing medium into the container C of the vibrating apparatus, and 30 g of the silicone-based filler was further charged and mixed. Next, the vibrating device was moved to the container C as shown in FIG.
While the container C is vibrated while being held at an angle of about 45 degrees from the state shown in FIG. 4, the film is turned upside down with the binder layer side having the filler attached thereto, and the bottom of the container C is set to 30 cm.
/ Min at a speed of ／/ min. As a result, the filler is struck by the vibrating pressurizing medium and is embedded in the binder layer in a state of being partially protruded, thereby forming a filler layer.

Next, the laminate was put into an aqueous solution obtained by adding 0.1 part by weight of a surfactant (trade name: Liponox NC-95 Lion Corporation) to 100 parts by weight of ion-exchanged water. The surplus filler was removed by giving a sound wave, rinsed sufficiently with ion-exchanged water, and then the surface was drained with an air knife. Then, in a 40 ° C.
After leaving it to dry for a day, it was cooled at room temperature to obtain a filler lens of Example 1. The gel fraction of the binder layer of this filler lens was 64%.

Example 2 On one side of the same film as in Example 1, an isocyanate-based curing agent (trade name: L-45, manufactured by Soken Chemical Co., Ltd.) was added to 100 parts by weight of the acrylic polymer a. Parts by weight and an epoxy curing agent (trade name: E
-5XM (manufactured by Soken Chemical Co., Ltd.) was applied with a reverse coater so that the thickness after drying was 5 μm, and dried at 100 ° C. for 2 minutes.
An ET film (trade name: 3811, manufactured by Lintec Co., Ltd.) was laminated and left in a constant temperature bath at 40 ° C. for 7 days to cure the binder layer. This film is cut into A5 plates and peeled off.
The ET film was peeled off. The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Example 2. The gel fraction of the binder layer of this filler lens was 90%.

Comparative Example 1 Comparative Example 1 was carried out in the same manner as in Example 1 except that no curing agent was used in the composition of the adhesive.
Was obtained. The gel fraction of the binder layer of this filler lens was 1%.

[Comparative Example 2] In Example 1, the pressure-sensitive adhesive was mixed with 0.2 parts by weight of an isocyanate-based curing agent (trade name: L-45, manufactured by Soken Chemical Co., Ltd.) based on 100 parts by weight of the acrylic polymer a. Part and epoxy curing agent (trade name: E
-5XM (manufactured by Soken Chemical Co., Ltd.) except that the amount was changed to 0.1 part by weight to obtain a filler lens of Comparative Example 2. The gel fraction of the binder layer of this filler lens was 42%.

Observation of Filler Layer and Measurement of Protrusion of Filler The planes and cross sections of the filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2 were observed with an electron microscope. FIG.
5 is a plan view and a cross section of the filler lens of Example 1, FIGS. 6 and 7 are a plan view and a cross section of the filler lens of Example 2,
8 and 9 are micrographs of the filler lens of Comparative Example 1 taken at a magnification of 2000 times. FIG. 10 and FIG. 4 and 5, in the filler lens of Example 1, the filler layer is a uniform single layer in a state where the filler protrudes from the binder layer such that the proportion of the protrusion of the filler becomes 55%.
6 and 7, in the filler lens of Example 2, the filler layer is a uniform single layer in a state where the filler projects from the binding layer such that the percentage of filler projection is 66%. on the other hand,
8 and 9, in the filler lens of Comparative Example 1, the filler layer is a uniform single layer in a state where the filler projects from the binder layer such that the proportion of the filler projection is 24%. FIG.
In the filler lenses of Comparative Examples 2 from 0 and 11, the filler layer is a uniform single layer in a state where the filler projects from the binder layer such that the proportion of the filler projection is 39%.

Optical Property Tests For the filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2, light was incident from the filler 3 side as shown in FIG. As shown in the figure, the haze (total light diffusivity (H
z))% was measured using a spectrophotometer UV3100 manufactured by Shimadzu Corporation. The measurement results are shown in Table 1.

Confirmation of Paper Whiteness and Uniformity The filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2 were placed on a flat plate whose surface was subjected to aluminum evaporation.
The paper white property was visually confirmed by placing the filler surface upward. When the background was close to paper white, it was evaluated as ○, and when the background color of aluminum appeared, it was evaluated as ×. At this time, the uniformity of the paper white color was also evaluated by visual observation, and was evaluated as ○ when uniform, and x when partially uneven. Table 1 shows the evaluation results of paper whiteness and uniformity.

Reliability Test The filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2
It is left for 500 hours in a high-temperature and high-humidity bath at 0 ° C. and 90% RH, left for 24 hours under normal temperature and normal humidity, and then, as shown in FIG. As shown in FIG. 2B, the haze (total light diffusivity (Hz))% when incident from the film 1 side was measured using a spectrophotometer UV3100 manufactured by Shimadzu Corporation. The measurement results are shown in Table 1.

[0040]

[Table 1]

According to Table 1, in the case of the filler lens of Example 1 or 2, the initial haze is about 87 to 90% with respect to the incident light in either the filler side or the film side, which is practically sufficient. It had light diffusivity and good paper whiteness. In the filler lenses of Comparative Examples 1 and 2, the initial haze was about 75 to 81%, and the paper whiteness was insufficient. In the reliability test, the filler lenses of Examples 1 and 2 showed little change in the haze value and good reliability. On the other hand, in the filler lenses of Comparative Examples 1 and 2, the haze was 10 to 15
%, Which is difficult to use for displays and the like. From the above, the filler lens of the present invention,
13 is inserted between a liquid crystal cell 11 provided with a polarizing plate 10 on both sides as shown in FIG. 13 and a reflecting plate 12, or an aluminum vapor-deposited layer 13 is formed on a film 1 of a filler lens as shown in FIG. Thus, it can be used as a diffuse reflection plate. Therefore, when the filler lens of the present invention is used for a reflective liquid crystal display, it is highly reliable and can diffuse light efficiently.

[0042]

As described above, according to the present invention,
Since it has a filler layer embedded in a single layer in a state where the proportion of the filler projecting from the surface layer of the binder layer laminated on the base is 50% or more, it is higher than the conventional filler lens. A filler lens having uniform light diffusion performance can be obtained. Further, the gel fraction of the binder layer is 60%.
As described above, a filler lens excellent in reliability can be obtained without deterioration in light diffusion performance even when left in a high-temperature and high-humidity environment. Therefore, when the filler lens of the present invention is used for displays such as LCDs, ELs, and FEDs, it is possible to design a liquid crystal display having a wide viewing angle, high luminance, and high contrast, and extremely excellent industrial effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of a filler lens of the present invention.

FIG. 2 is a diagram illustrating a method of calculating a ratio of a filler protruding from a binding layer.

FIG. 3 is a front sectional view of a vibration device suitable for producing a filler lens of the present invention.

FIG. 4 shows the plane of the filler lens of Example 1 as 2000.
It is a micrograph shown by magnification.

FIG. 5 shows a cross section of the filler lens of Example 1 at 2000.
It is a micrograph shown by magnification.

FIG. 6 shows the plane of the filler lens of Example 2 set to 2000.
It is a micrograph shown by magnification.

FIG. 7 shows a cross section of the filler lens of Example 2 of 2000.
It is a micrograph shown by magnification.

FIG. 8 shows the plane of the filler lens of Comparative Example 1 as 2000.
It is a micrograph shown by magnification.

FIG. 9 shows a cross section of the filler lens of Comparative Example 1 of 2000.
It is a micrograph shown by magnification.

FIG. 10 shows the plane of the filler lens of Comparative Example 2 as 200.
It is a micrograph shown by 0 time.

FIG. 11 shows a cross section of the filler lens of Comparative Example 2 of 200.
It is a micrograph shown by 0 time.

FIG. 12 is a schematic diagram for explaining a direction of incident light with respect to a filler lens.

FIG. 13 is a schematic view illustrating an example of a method of using the filler lens of the present invention.

FIG. 14 is a schematic view showing an example of a method for using the filler lens of the present invention.

FIG. 15 is a cross-sectional view schematically illustrating an example of a conventional filler lens.

FIG. 16 is an optical microscope photograph of a plane of a filler lens formed by using a pressure roller, which is photographed with a 10 × objective lens.

FIG. 17 is a cross-sectional view schematically illustrating an example of a conventional filler lens.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Binder layer, 3 ... Filler, 3A ... Filler layer, L ... Filler lens

Claims (10)

[Claims] 1. A binder layer having a gel fraction of 60% or more is laminated on a substrate directly or via another layer, and the proportion of filler protrusion on the surface layer of the binder layer is 50%. A filler lens comprising a filler layer embedded in a protruding state as described above. 2. The filler lens according to claim 1, wherein the filler is an organic filler. 3. The filler has a volume average particle diameter of 2 to 1
The filler lens according to claim 1, wherein the thickness is 5 μm. 4. The filler has a particle size distribution of 0.8 to 0.8.
The filler lens according to claim 1, wherein the value is 1.0. 5. The filler lens according to claim 1, wherein the filler is a sphere having a roundness of 80% or more. 6. A filler having a refractive index of 1.42-1.
The filler lens according to any one of claims 1 to 5, wherein the number is 55. 7. The filler lens according to claim 1, wherein the substrate is a transparent substrate having a total light transmittance of 85% or more. 8. On a substrate, directly or via another layer,
A step of laminating a binder layer of a pressure-sensitive adhesive containing a resin and a curing agent, a step of curing the binder layer to increase the gel fraction to 60% or more, a step of attaching a filler to the binder layer, The ratio of filler protrusion by the pressurized medium is 5
A method of manufacturing a filler lens, comprising: a step of embedding the binder layer in the binder layer so as to have a concentration of 0% or more; and a step of removing excess filler adhered to the laminate obtained in the step. 9. The pressurized medium is a granular material, and the pressurized medium is vibrated to strike the filler,
The method for manufacturing a filler lens according to claim 8, wherein the filler is embedded in the binder layer. 10. The method for producing a filler lens according to claim 8, wherein in the step of removing the surplus filler, the removal is performed using water or an aqueous solution.