JP2001228311A - Filler lens and method for producing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a filler lens more excellent in uniform light diffusing property than a conventional light diffusing body and a method for producing the filler lens. SOLUTION: A binding layer 2 is laminated on a substrate 1 directly or by way of another layer and a filler layer 3A is embedded in the surface of the binding layer in such a way it protrudes from the surface of the binding layer to obtain the objective filler lens. The filler layer 3A comprise an organic filler 3 having 2-15 μm volume average particle diameter.

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 on which an aluminum film or the like having a high reflectance is adhered is arranged on the back surface of the liquid crystal panel, and external light incident from the display surface side is reflected by the reflection plate to illuminate the 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 appropriately between the liquid crystal panel and the reflective plate is interposed between the liquid crystal panel and the reflective plate to set the background color to paper white to prevent the background color of aluminum from appearing and deteriorating the contrast. Getting closer is being done. 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 light diffuser in which a binder resin in which a light diffusing filler is dispersed is laminated on one surface of a transparent resin film and a light diffusing layer is provided. 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. 21 schematically shows a light diffuser obtained by such a manufacturing method, in which a filler 23 is contained in a binder resin 22 on a film 21.
Are dispersed to form a light diffusion layer.

[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). In addition, the conventional light diffuser has a problem in stable productivity in that problems such as poor dispersion of the filler, agglomeration, precipitation, and the like are likely to occur, and the optical characteristics are easily changed by the film thickness.

Accordingly, the present inventors have proposed a structure in which a filler is embedded in a single layer so that a part thereof protrudes into the surface layer of the binder layer, and if the protruded filler forms a fine lens, light transmission is achieved. Considering that a light diffuser having high light diffusivity and high light diffusivity could be obtained, the following production method was attempted. Forming a binder layer on the base material, attaching a filler to the binder layer, leveling the filler attached to the surface of the binder layer, embedding the filler in the binder layer using a pressure roller, excess To remove the filler. In the above-described manufacturing method, the filling density of the filler in the plane direction is likely to be non-uniform, and a portion where the packing density of the particles is high and a portion where the density is high are likely to occur. Therefore, it tends to be an uneven filler lens having different light diffusivity and transmittance depending on the location. Furthermore, in the above-mentioned method, it was also difficult to embed the filler in the binder layer at a uniform depth. In other words, due to bending of the pressure roller, variation in the thickness of the binder layer, variation in the thickness of the film, etc., a partial pressure difference is generated, and the filler is deeply embedded and embedded in a place where a large pressure is applied. The binder soaks up from the gap between the filled fillers, and other fillers adhere thereto, so that the filler layer is likely to be a multilayer. On the other hand, since the filler is not sufficiently buried in the binder layer in a place where the pressure is small, defects such as filler removal easily occur in a step of removing the excess filler. This phenomenon was remarkable when the treatment was performed on a large area or when a filler having a volume average particle diameter of 15 μm or less was used. In particular, when a filler having a volume average particle diameter of 15 μm or less is used, the specific surface area of the filler is increased, so that the filler is affected by interparticle force such as van der Waals force or electric adhesion force due to triboelectric charging. In addition, since the fluidity of the filler is significantly deteriorated, it is difficult to uniformly and densely attach the filler to the surface of the binder layer. Further, in the case of a filler having a volume average particle diameter of 15 μm or less, the pressure of the pressure roller is dispersed, and the pressure applied to each filler is reduced. Cannot be embedded to a uniform depth. Therefore, the filling density of the filler is low, and the variation in the filling depth of the filler into the binder layer increases due to the partial variation in the pressing force. As a result, it is difficult to produce a filler lens having uniform diffusivity and transmissivity, and it is not at a level that can be used industrially as a light diffuser. FIG. 22 is an optical microscope photograph of a plane of a filler lens manufactured using a methyl silicone 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, Reference numeral 23 denotes an electron micrograph of a cross section of the filler lens taken at 2000 times. From FIG. 22, it can be seen that the filling density of the filler is non-uniform, and the filler is partially multilayered. In addition, it can be seen from FIG. 23 that the filling depth of the filler in the binder layer is not uniform. Therefore, the present invention is a conventional filler lens manufactured using a coating material in which a filler is dispersed in a binder, that is, a light diffuser in which a filler is present in a multilayer in a binder layer, and a pressure roller. An object of the present invention is to provide a filler lens having uniform light diffusivity and excellent light transmissivity as compared with a light diffuser produced by the method described above, and a method for producing the same.

[0006]

The filler lens of the present invention comprises a base, a binder layer laminated on the base directly or via another layer, and a binder layer formed on the surface of the binder layer. A filler layer comprising an organic filler having a volume average particle diameter of 2 to 15 μm embedded so as to partially protrude from the surface of the deposition layer.
Note that a coating or another layer that improves light diffusion may be formed on the surface of the filler layer.

[Detailed Description of the Invention] FIG. 1 is a sectional view schematically showing one example of a filler lens of the present invention. In this filler lens L, a binding layer 2 is directly laminated on a base 1, and a large number of organic fillers 3 are provided on the surface of the binding layer 2 so that the surface of the binding layer 2 has a high density in the surface direction. The filler layer 3 </ b> A is formed by being embedded in the substrate. As shown in FIG. 1, the filler layer 3A has a single layer and a uniform depth on the surface of the binder layer in order to sufficiently obtain uniform light diffusion and light transmittance by the organic filler. Are embedded so as to protrude from the surface of the binder layer. In particular, when used as a light diffuser for a liquid crystal display or the like, a uniform and uniform filler lens is required.

Therefore, the volume average particle diameter of the organic filler used in the filler lens of the present invention is 2 to 15 μm, preferably 2 to 10 μm. When the volume average particle diameter of the organic filler is smaller than 2 μm, the diffused light interferes with each other to exhibit an iridescent color, so that the contrast of the liquid crystal cell is reduced. On the other hand, in the case of an organic filler larger than 15 μm, the diffused light has coarse grain, and the edge portion of the liquid crystal image is blurred and visibility is reduced. Furthermore, when the volume average particle diameter is 1
When an organic filler larger than 5 μm is used, the area of the filler in the plane of the filler lens and the area of the gap between the fillers, that is, the area of the part that diffuses light and the area of the part that does not disperse light both increase. Can be visually confirmed, and therefore, uneven brightness occurs in the liquid crystal image. Further, the narrower the particle size distribution of the organic filler, the more uniformly the impact force from the pressurized medium in the production method of the present invention described later can be transmitted to the organic filler. For the same reason, the packing density of the organic filler in the plane direction can be made high and uniform. Therefore, in order to uniformly transmit the impact force from the pressurized medium to the organic filler, the particle size distribution of the organic filler is preferably 0.8 to 1.0, and more preferably 0.9 to 1.0. desirable.

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 organic fillers randomly extracted from a micrograph of a filler lens. -Volume average particle diameter = First, the diameter of 100 randomly extracted organic fillers is measured from a micrograph of the filler lens. From the diameter of the obtained organic filler, the volume of each organic filler is determined by regarding the organic filler as a true sphere. Next, the volume of each organic filler is accumulated to calculate the total volume of 100 organic fillers. Then 100
Among the organic fillers, the diameters of particles whose cumulative volume becomes 50% of the above-mentioned total volume by accumulating volumes in order of volume from the smallest organic filler to the largest organic filler. At this time, when the particles of the organic filler are not true spheres, the longest diameter is defined as the diameter of the organic filler. In the present specification, a filler lens is a digital microscope manufactured by Keyence Corporation (trade name: VH-6).
The measurement was performed using a transmitted light image photograph taken in 300).

Further, in order to uniformly transmit the impact force from the pressurized medium to the organic filler, the organic filler is preferably spherical and has a roundness of 85% or more, more preferably 90% or more. preferable. In the present invention, “roundness” is defined by the following equation. Roundness (%) = (4πA / B ² ) × 100 A: Projected area of organic filler B: Perimeter of organic filler This roundness is determined by, for example, photographing an organic filler with a transmission electron microscope and obtaining a projected image. It can be calculated from the above A and B obtained by analyzing the image using an image analyzer (for example, manufactured by Nippon Avionics Co., Ltd., trade name: EXECLII). As is clear from the above equation, the roundness is close to 100% when the organic filler is close to a true sphere, and smaller when the organic filler is irregular. In this specification, 10
The average value measured for each of the organic fillers is defined as roundness.

Further, the depth of embedding the organic filler in the binder layer can suppress the peeling of the organic filler from the binder layer, and can protrude from the surface of the binder layer to ensure light diffusion. Therefore, the diameter of the organic filler should be 10
~ 90%, preferably 30-80%, more preferably 4%
It is desirable that 0 to 80% is embedded.

The refractive index of the organic filler is preferably close to the refractive indexes of the base material and the binder layer.
When it is in the range of 42 to 1.55, high light transmittance can be obtained, which is preferable.

<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, but when used for a liquid crystal display or the like, the refractive index (JIS K-7142) is in the range of 1.45 to 1.55. Certain transparent substrates are 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 80% or more.
It is more preferably at least 85%. When the transparent substrate is used for a small and light liquid crystal display, the transparent substrate is more preferably a film, and the thickness of the transparent substrate is preferably thinner from the viewpoint of weight reduction. Is considered, 1 μm to 5 mm
It is preferable to use those in the range of 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 adhesive include resin adhesives such as polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins. These may be used alone or in combination of two or more. In particular,
Acrylic pressure-sensitive adhesives are preferable because they are excellent in water resistance, heat resistance, light resistance, and the like, have good adhesive strength and transparency, and when used in a liquid crystal display, can easily adjust the refractive index to conform to them. As the acrylic adhesive, acrylic acid and its esters, methacrylic acid and its esters, acrylamide, homopolymers of acrylic monomers such as acrylonitrile or copolymers thereof,
Copolymers of at least one of the above acrylic monomers and an aromatic vinyl monomer such as vinyl acetate, maleic anhydride, and styrene can be mentioned. In particular, ethylene acrylate, butyl acrylate, which exhibits adhesiveness,
Main monomers such as 2-ethylhexyl acrylate, and monomers such as vinyl acetate, acrylonitrile, acrylamide, styrene, methacrylate, and methyl acrylate as cohesion components, and methacrylic acid and acrylic acid, which further improve the adhesive strength and impart a crosslinking starting point, It is a copolymer composed of functional group-containing monomers such as itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, acrylamide, methylolacrylamide, glycidyl methacrylate, and maleic anhydride. ) Is in the range of −60 to −15 ° C. and the weight average molecular weight is in the range of 200,000 to 1.2 million. A binder layer having a Tg lower than −60 ° C. or a binder having a weight average molecular weight of less than 200,000 is too soft, so that the organic filler once adhered is peeled off by the impact force of the pressurized medium, and the filler is removed. And other defects are likely to occur. Further, the binder is attached to the organic filler that has been peeled off once, and the organic filler may adhere to the filler layer again. Furthermore, in the binder layer which is too soft, the organic filler rotated by the impact of the pressurized medium in the vertical direction on the surface of the binder layer causes the portion of the organic filler to which the adhesive has adhered to appear on the surface of the filler layer, where Other organic fillers may adhere, or the binder may permeate from the gaps between the organic fillers due to the impact force of the pressurized medium or the capillary phenomenon, and the other organic fillers may adhere thereto. Such a phenomenon is not preferable because a soft binder layer tends to form a multilayer filler layer and lowers light transmittance. On the other hand, a binder layer having a Tg higher than −15 ° C. or a binder layer having a weight-average molecular weight of more than 1.2 million is not preferable because the organic filler is liable to drop off in a step of washing excess filler or the like due to insufficient adhesion. .

In the pressure-sensitive adhesive, as a curing agent, for example, a metal chelate-based, isocyanate-based, or epoxy-based cross-linking agent can be used singly or as a mixture of two or more. Adhesive strength of binding layer (JIS Z 0237
8) is practically preferable if it is blended so as to be 100 g / 25 mm or more. If the adhesive strength is less than 100 g / 25 mm, the organic filler may be detached or the environmental resistance may be deteriorated. In particular, under high temperature and high humidity, the binder layer may peel off from the transparent substrate. Further, from the viewpoint of reliability, it is preferable that the gel fraction after curing is 40% or more, more preferably 60% or more. If the gel fraction is less than 40%, the binder layer is softened under high temperature and high humidity, and the organic filler may sink in the binder layer, resulting in a change in optical characteristics. Further, a UV curable binder to which a photopolymerizable monomer, oligomer, polymer and photopolymerization initiator are added may be used as the binder.

(3) Organic Filler As the organic filler of the present invention, acrylic resin, polystyrene resin, and the like are preferable in terms of light transmittance and adhesion to a binder layer.
Examples include polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, Teflon, divinylbenzene, phenol resin, urethane resin, cellulose acetate, nylon, cellulose, benzoguaninane, melamine and the like. Acrylic resin beads and silicone resin beads are preferable in terms of light resistance. Furthermore, to form the filler layer more uniformly and densely,
It is most preferable to use silicone beads such as methyl silicone having high fluidity. Since inorganic fillers such as silica and soda glass have poor adhesion to the binder layer, the fillers fall off during the filler embedding step or the surplus filler washing step, and the fillers are removed.

(4) Other layers Between the substrate 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 substrate 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 the filler lens having the above-described structure, and a binder layer is laminated on a substrate directly or via another layer. A step of embedding an organic filler having a volume average particle diameter of 2 to 15 μm in the binder layer with a pressurized medium, and a step of removing excess filler attached to the laminate obtained in the step. Features. Before the step of, by performing a step of attaching an organic filler having a volume average particle diameter of 2 to 15 μm to the surface of the binder layer,
It is preferable since defects in appearance such as removal of the organic filler are reduced and the organic filler can be reliably embedded. In addition, in order to adjust the embedding of the organic filler into the binder layer, in the case where the binder layer contains a resin having a crosslinking point and a curing agent, the binder layer was protected with a peelable PET film or the like after the step. In this state, aging treatment may be performed at a temperature of about 20 to 80 ° C. for about 3 to 14 days to cause the binder and the curing agent to react. Further, if a step of applying heat or moisture after the step to soften the binder layer of the laminate is performed, the organic filler and the binder layer become familiar, and in particular, the total light transmittance and reliability are improved. You can also do it.

<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. The thickness of the binder layer is preferably about 0.1 to 1.5 times the volume average particle diameter of the filler to be embedded.

[Step 2: Attachment of Organic Filler to Binder Layer Surface] Next, it is desirable to attach an organic filler to the surface of the binder layer on the substrate. As a method, for example,
The organic filler filled in the container may be fluidized by vibration or fluidizing air, and the substrate may be passed through the fluidized organic filler, or the filler may be sprayed on the binder layer by air spray. At this time, since the organic filler has a higher fluidity than the inorganic filler, it can be easily mixed with air at the time of air spray, or in a fluidized state in a container, and can be uniformly attached to the surface of the binder layer. . By uniformly adhering the organic filler to the surface of the binder layer, defects such as filler removal are reduced, and at the same time, the pressurizing medium is applied to the binder layer in the step of embedding the organic filler into the binder layer by a later pressurizing medium. Adhesion can also be prevented. And here, the organic filler only needs to adhere to the surface of the binder layer simply by the adhesive force of the binder layer.

[Step 3: Embedding Organic Filler in Binder Layer] Next, the organic filler adhered to the surface of the binder layer is embedded in the binder layer by the impact force of the pressurized medium. As a method, a pressurized medium is charged into an appropriate container, the pressurized medium is vibrated together with the container, and a substrate in which an organic filler is adhered to the surface of the binder layer is put into the pressurized medium, or This gives the organic filler an impact force. According to such a method, when a filler lens having a large area is manufactured, the organic filler is hit with a pressurized medium and embedded in the surface layer of the binder layer. The pressurized medium has the advantage that the embedded depth of the organic filler is made uniform by hitting the minute area with a uniform force. At this time, 0.5 to 100 parts by weight of the pressurized medium
When a pressurized medium pre-mixed with about 2.0 parts by weight of an organic filler is used, other organic fillers are uniformly applied to the gaps between the organic fillers attached to the surface of the binder layer in the previous step due to the impact force of the pressurized medium. Since it can be pushed into the depth, the filling density in the planar direction of the filler layer can be made higher and uniform, which is preferable. By such a method, the organic filler protrudes from a part of the binder layer in a state where the embedding depth is uniform, and is uniformly and densely embedded in the whole, so that the organic filler is in a single layer state without being laminated in the binder layer. Is formed as a filler layer. In addition, as an external force applied to bury the organic filler, rotation, dropping, 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 embedding the organic filler will be exemplified. The pressurized medium is a granular material that acts to embed the organic filler in the binder layer by hitting the organic 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 the like. Consisting of various metals and alloys, or Al ₂ O ₃ , SiO
₂ , ceramics such as TiO ₂ , ZrO ₂ , and SiC, as well as glass and hard plastics 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 organic 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 organic filler and the depth of embedding of the organic filler, but the diameter is 2 mm or less, and further 0.3 to 2.0 m.
About m is preferable.

[Step 4: Removal of Excess Filler] After the step of embedding the organic filler in the binder layer, the excess filler is removed. The surplus filler, for example, is imperfectly embedded in the binder layer, or refers to an organic filler or the like only attached to the embedded filler by interparticle force such as electrostatic force or van der Waals force, Such surplus filler can be removed by applying a fluid pressure to the filler layer by washing with water, air blowing, or the like. At this time, in the case of an organic filler having a volume average particle diameter of 2 to 15 μm, removal by fluid pressure alone tends to be insufficient, and therefore, an ultrasonic wave using an aqueous solution such as ion-exchanged water to which a surfactant or the like is added is used. After washing and the like, it is preferable to sufficiently rinse with deionized water or the like and then dry.

[0024]

Next, an embodiment of the present invention will be described. <Polymerization example of acrylic polymer a> 94 parts by weight of n-butyl acrylate, 3 parts by weight of acrylic acid, 1 part by weight of 2-hydroxyacrylate, and peroxide in a flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet tube Benzoyl 0.3
Parts by weight, 40 parts by weight of ethyl acetate, and 60 parts by weight of toluene. Then, nitrogen was introduced from a nitrogen introduction tube to make the inside of the flask a nitrogen atmosphere, and then heated to 65 ° C. to perform a polymerization reaction for 10 hours. Average molecular weight about 1,000,000, Tg about -50
An acrylic polymer solution at a temperature of ° 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, refractive index 1.49, total light transmittance 92.4, manufactured by Fuji Photo Film Co., Ltd.). On one side of this film, 0.2 part by weight of an isocyanate-based curing agent (trade name: L-45, manufactured by Soken Chemical Co., Ltd.) and 100 parts by weight of an epoxy-based curing agent (E-5XM: Soken) (A product of Chemical Co., Ltd.) was added by a reverse coater so that the thickness after drying was 3 μm.
The film was dried at 0 ° C. for 2 minutes to form a binder layer.
It was cut into 5 plates.

Next, as an organic filler, the volume average particle size is 4.5 μm, the particle size distribution is 0.94, and the refractive index is 1.
43, using methyl silicone beads (trade name: Tospearl 145, manufactured by GE Toshiba Silicone Co., Ltd.) having a roundness of 96%, the organic filler was put into a perforated plate container which blows air from the bottom. Thereafter, the container was vibrated to bring the organic filler into a fluidized state by a synergistic effect of the vibration and the jet air. The film having the binder layer formed on the surface was passed through the film with appropriate time, and a filler was attached to the surface of the binder layer.

Next, an organic filler was buried in the surface layer of the binder layer to form a filler layer using the vibration device shown in FIG. The container C of this 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.
A columnar portion c3 that protrudes upward and reaches a height approximately equal to that of the opening c1 is provided in a protruding manner. On the other hand, the vibration mechanism V
A diaphragm f3 is mounted thereon via coil springs f1 and f2, a vertical axis f4 extending upward is protruded at the center of the upper surface of the diaphragm f3, and a motor f5 is fixed to the center of the lower surface of the diaphragm f3. The weight f7 is eccentrically attached to the output shaft f6 of the motor f5. The 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, and is excited when the motor f5 is driven to rotate the weight f7. It has become.

3 kg of spherical zirconia spheres having a particle diameter of 0.5 mm are charged into the container C of the vibrating apparatus as a pressurizing medium, and 30 g of the silicone-based organic filler is further added.
They were charged and mixed. Next, while the container C is vibrated while the container C is tilted 45 degrees from the state shown in FIG. 5, the film is turned upward with the binder layer side to which the organic filler is attached. The bottom of the container C to 3
It was passed through the pressurized medium by moving at a speed of 0 cm / min. As a result, the organic filler was hit by the vibrating pressurizing medium and was embedded in the surface layer of the binder layer to form a filler layer.

Next, 0.1% of a surfactant (Liponox NC-95 Lion Corporation) was added to ion-exchanged water.
The filler lens was immersed in an aqueous solution and an ultrasonic wave was applied to wash and remove excess organic filler. After rinsing with an ion-exchanged water, the surface was drained with an air knife. Then, after leaving it to dry in a constant temperature bath at 40 ° C. for 5 days, it was cooled at room temperature to obtain a filler lens of Example 1.

[Example 2] The binder of Example 1 was coated on one surface of the same film as in Example 1 with a reverse coater so that the thickness after drying was 3 µm, and the coating was performed at 100 ° C for 2 minutes. After drying to form a binder layer, the film was cut into A5 plates. In the subsequent steps, the organic filler to be used is methyl silicone beads having a volume average particle size of 2.6 μm, a refractive index of 1.43, a particle size distribution of 0.90, and a roundness of 94% (trade names: Tospearl 130, GE Toshiba) Silicone). The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Example 2.

Example 3 The same binder as in Example 1 was coated on one side with a reverse coater on one side of the same film as in Example 1 so that the thickness after drying was 4 μm, and the coating was performed at 100 ° C. for 2 minutes. After drying to form a binder layer, the film was cut into A5 plates. In the subsequent steps, methyl methacrylate beads having a volume average particle diameter of 5.0 μm, a refractive index of 1.50, a particle diameter distribution of 0.94, and a roundness of 93% (trade name: MX-500, Soken) Chemical Co.).
The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Example 3.

Example 4 On one side of the same film as in Example 1, the binder of Example 1 was applied with a reverse coater so that the thickness after drying was 5 μm, and the coating was performed at 100 ° C. for 2 minutes. After drying to form a binder layer, the film was cut into A5 plates. In the subsequent steps, methyl methacrylate beads having a volume average particle diameter of 10.8 μm, a refractive index of 1.50, a particle diameter distribution of 0.94, and a roundness of 94% (trade name: MX-1000, Soken Chemical Co., Ltd.). Subsequent steps are performed in the same manner as in the first embodiment.
Was obtained.

Example 5 The same binder as in Example 1 was coated on one side with a reverse coater so that the thickness after drying was 6 μm on one side of the same film as in Example 1, and the coating was performed at 100 ° C. for 2 minutes. After drying to form a binder layer, the film was cut into A5 plates. In the subsequent steps, methyl methacrylate beads having a volume average particle diameter of 14.9 μm, a refractive index of 1.50, a particle diameter distribution of 0.96, and a roundness of 92% (trade name: MX-1500H, Soken Chemical Co., Ltd.). The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Example 5.

[Comparative Example 1] The binder of Example 1 was applied on one surface of a film similar to that of Example 1 by a reverse coater so that the thickness after drying became 3 μm, and was heated at 100 ° C. for 2 minutes. After drying to form a binder layer, the film was cut into A5 plates. In the subsequent steps, the filler used has a volume average particle size of 4.1 μm, a refractive index of 1.52, and a particle size distribution of 0.1.
34, soda glass with 67% roundness (trade name: MB-1)
0, manufactured by Toshiba Barotini). The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Comparative Example 1. In addition, irregular particles were included in this filler, and the longest diameter was measured as the diameter of each filler.

[Comparative Example 2] The binder of Example 1 was dried on one side of the same film as in Example 1 to a thickness of 15 μm.
After coating with a reverse coater and drying at 100 ° C. for 2 minutes to form a binder layer, this film was cut into A5 plates. In the subsequent steps, the filler used is a methyl methacrylate filler having a volume average particle diameter of 21.0 μm, a refractive index of 1.50, a particle diameter distribution of 0.29, and a roundness of 94% (trade name: MR-20G, Soken Chemical) Company). The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Comparative Example 2.

Comparative Example 3 The binder of Example 1 was dried on one side of the same film as in Example 1 to a thickness of 20 μm.
After coating with a reverse coater and drying at 100 ° C. for 2 minutes to form a binder layer, this film was cut into A5 plates. In the subsequent steps, soda glass having a volume average particle diameter of 29.3 μm, a refractive index of 1.52, a particle diameter distribution of 0.23, and a roundness of 94% (trade name: GB) was used.
-731, Toshiba Barotini). The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Comparative Example 3.

Observation of Filler Lens The planes and cross sections of the filler layers of the filler lenses of Examples 1 to 5 and Comparative Examples 1 to 3 were observed with an electron microscope. 3 to 12 show electron micrographs of the filler lenses of Examples 1 to 5 taken at a magnification of 1000 times, and FIGS. 13 to 18 show the filler lenses of Comparative Examples 1 to 3 at 1000 times magnification. 3 is an electron micrograph taken at a magnification of FIG.

As can be seen from FIGS.
The filler lens of No. 5 has a high filling density in the surface direction and is uniform, and furthermore, the embedded depth in the binder layer is also uniform. On the other hand, as is clear from FIGS. 13 and 17, Comparative Examples 1 and 3
In the case of the filler lens, a large number of falling marks (voids in the center of FIGS. 13 and 17), which are considered to be marks from which the filler was dropped in the washing step of the surplus filler, were observed. Further, in Comparative Examples 2 and 3 of FIGS. 15 to 18, since the volume average particle diameter of the filler is large, it is clear that the area of the gap between the filler and the filler is large.

Evaluation of uniformity of transmitted light The filler lenses of Examples 1 to 5 and Comparative Examples 1 to 3 were visually observed through the transmitted light to evaluate the uniformity of the transmitted light. A: uniform when the entire A5 plate is uniform; bright spots where light transmittance is abnormally high due to places such as missing fillers or gaps between fillers; or dark spots where light transmittance is abnormally low due to the presence of the filler in multiple layers. Was evaluated as x when it could be visually confirmed. Table 1 shows the evaluation results of the uniformity of the transmitted light.

Evaluation of Fineness of Grain of Transmitted Light The filler lenses of Examples 1 to 5 and Comparative Examples 1 to 3 were visually observed through transmitted light to evaluate the fineness of the grain of transmitted light. When the transmitted light looked smooth, it was evaluated as ○, and when it was grainy, it was evaluated as ×. Table 1 shows the evaluation results of the uniformity of the transmitted light.

Optical Property Test FIG. 19 shows the filler lenses of Examples 1 to 5 described above.
The total light transmittance: Tt (%) and the total light diffusivity: Hz (%) when light was incident from the filler side were measured using a spectrophotometer UV3100 manufactured by Shimadzu Corporation. Table 2 shows the measurement results. In addition, as a characteristic required for a filler lens for a display in practical use, the balance between the luminance and the viewing angle varies depending on the use of the display, but Tt is preferably 70% or more and Hz is preferably 60% or more.

[0042]

[Table 1]

[0043]

[Table 2]

As is clear from Tables 1 and 2, the optical characteristics of the filler lens having the structure according to the present invention show practically sufficient values for both the total light transmittance and the total light diffusivity. It has light diffusivity and transparency. And
Since fine organic fillers were used, the light had uniform and fine grained transmitted light. Further, from Table 2, it can be understood that by changing the volume average particle diameter of the organic filler, it is possible to change and adjust the light diffusivity and light transmittance. On the other hand, as in Comparative Examples 1 and 3,
In the case of a filler lens using an inorganic filler, the adhesion between the binder layer and the filler was poor, so that the filler dropped off during washing, and the spot was abnormally bright and the transmitted light was non-uniform. Further, in the case of using a filler having a volume average particle diameter larger than 15 μm as in Comparative Examples 2 and 3, the grain of transmitted light was rough, and the level could not be used for display applications. From this, for example, as shown in FIG. 20, the filler lens of the present invention is applied to the transmission type liquid crystal display as shown in FIG.
When inserted between the liquid crystal cell 11 and the liquid crystal cell 11 provided with the polarizing plates 10 on both sides, the light from the backlight unit 12 can be efficiently transmitted, and the light can be diffused efficiently and finely. is there. Therefore, since the incident light is less attenuated, it is possible to reduce the battery consumption and secure a high viewing angle while obtaining the conventional light amount. Furthermore, since the filler lens of the present invention is excellent in light diffusivity, the background color of the backlight can be made closer to paper white color, and the contrast of the liquid crystal display can be improved, which is preferable.

[0045]

As described above, the filler lens of the present invention has a single-layer filler on the surface of the binder layer laminated on the substrate, with a part protruding from the surface of the binder layer. A layer is formed, and the filler has a volume average particle diameter of 2 to 2.
Since an organic filler of 15 μm is used, it has practically sufficient light transmission and light diffusion properties. In addition, since fine fillers that cannot be visually identified are used, it is possible to obtain transmitted light and diffused light with uniform and fine grain.
Further, by changing the volume average particle diameter of the organic filler between 2 and 15 μm, it is possible to adjust the light diffusivity and light transmittance. Therefore, when the filler lens of the present invention is used for displays such as LCDs, ELs, and FEDs, since the attenuation of incident light is small, it is possible to design a liquid crystal display having a wide viewing angle, high brightness, and high contrast. It has extremely excellent effects.

[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 front sectional view of a vibrating device suitable for producing a filler lens of the present invention.

FIG. 3 shows a plan view of the filler lens of Example 1 with a plane of 1000;
It is an electron microscope photograph shown by magnification.

FIG. 4 shows the cross section of the filler lens of Example 1 as 1000.
It is an electron microscope photograph shown by magnification.

FIG. 5 shows a plan view of the filler lens of Example 2 as 1000.
It is an electron micrograph shown in magnification.

FIG. 6 shows a cross section of the filler lens of Example 2 of 1000
It is an electron microscope photograph shown by magnification.

FIG. 7 shows the plane of the filler lens of Example 3 set to 1000.
It is an electron microscope photograph shown by magnification.

FIG. 8 shows the cross section of the filler lens of Example 3 as 1000.
It is an electron microscope photograph shown by magnification.

FIG. 9 shows that the plane of the filler lens of the fourth embodiment is 1000
It is an electron microscope photograph shown by magnification.

FIG. 10 shows the cross section of the filler lens of Example 4 as 100.
It is an electron microscope photograph shown by 0 time.

FIG. 11 shows the plane of the filler lens of Example 5 as 100
It is an electron microscope photograph shown by 0 time.

FIG. 12 shows the cross section of the filler lens of Example 5 as 100
It is an electron microscope photograph shown by 0 time.

FIG. 13 shows a plan view of the filler lens of Comparative Example 1 as 100
It is an electron microscope photograph shown by 0 time.

FIG. 14 shows a cross section of the filler lens of Comparative Example 1 of 100.
It is an electron microscope photograph shown by 0 time.

FIG. 15 shows a plan view of the filler lens of Comparative Example 2 as 100
It is an electron microscope photograph shown by 0 time.

FIG. 16 shows a cross section of the filler lens of Comparative Example 2 of 100.
It is an electron microscope photograph shown by 0 time.

FIG. 17 shows a plan view of the filler lens of Comparative Example 3 as 100
It is an electron microscope photograph shown by 0 time.

FIG. 18 shows a cross section of the filler lens of Comparative Example 3 of 100.
It is an electron microscope photograph shown by 0 time.

FIG. 19 is a schematic diagram for explaining the direction of incident light with respect to a filler lens.

FIG. 20 is a schematic view showing an example of a method for using the filler lens of the present invention.

FIG. 21 is a cross-sectional view schematically illustrating an example of a conventional filler lens.

FIG. 22 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. 23 is an electron micrograph of a cross section of a filler lens formed using a pressure roller taken at a magnification of 2000 times.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Binder layer, 3 ... Organic filler, 3A ... Filler layer, L ... Filler lens

Claims (10)

[Claims] 1. A substrate, a binder layer laminated on the substrate directly or via another layer, and a surface layer of the binder layer
A filler layer comprising an organic filler having a volume average particle diameter of 2 to 15 μm embedded so as to partially protrude from the surface of the binder layer. 2. The particle size distribution of the organic filler is 0.8.
2. The filler lens according to claim 1, wherein the number is from 1.0 to 1.0. 3. 3. The filler lens according to claim 1, wherein the organic filler is spherical and has a roundness of 85% or more. 4. The organic filler has a refractive index of 1.42 or more.
The filler lens according to any one of claims 1 to 3, wherein the ratio is 1.55. 5. The organic filler according to claim 1, wherein the organic filler is an acrylic resin or a silicone resin.
A filler lens according to any one of the above. 6. The filler lens according to claim 1, wherein the substrate is a transparent substrate having a total light transmittance of 80% or more. 7. A step of laminating a binder layer directly or via another layer on a substrate, a step of embedding an organic filler having a volume average particle diameter of 2 to 15 μm in the binder layer by a pressurized medium, Removing excess filler attached to the laminate obtained in the step. 8. Before the step of embedding an organic filler having a volume average particle diameter of 2 to 15 μm into the binder layer by the pressurizing medium, an organic filler having a volume average particle diameter of 2 to 15 μm is added to the binder layer. The method for producing a filler lens according to claim 7, further comprising a step of attaching the filler lens to a surface. 9. The pressure medium is a sphere having a diameter of 2 mm or less, and the filler is embedded in the binder layer by an impact force generated by vibrating the pressure medium. Or a method for producing a filler lens according to item 8. 10. The method for producing a filler lens according to claim 7, wherein the step of removing the surplus filler is performed by using water or an aqueous solution.