JP2001108806A - Filler lens and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [PROBLEMS] A light diffusion and light transmission with high uniformity,
Provided is a filler lens having excellent light transmittance as compared with a conventional light diffuser having a multilayered filler layer, and a method for manufacturing the same. SOLUTION: A binder layer is laminated on a base material directly or via another layer so that a standard deviation of a distance between filler particles in a plane direction is 0.4 or less, and a binder layer is provided. A filler is embedded by using a spherical pressurizing medium so that a part thereof protrudes from the surface of the laminate, and a surplus filler adhering to the laminated body is removed, thereby forming a filler layer to produce a filler lens.

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 luminance unevenness, 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 appropriately diffuses light is interposed between the liquid crystal panel and the reflective plate to prevent the background color of aluminum from deteriorating the contrast, and the background color is paper white. It has been done to approach. 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 diffusing layer 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 dispersing a filler in a solution in which a binder resin is mixed with a solvent to form a coating, and applying the coating on a film with a spray or a coater. FIG. 16 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 problem that it has light diffusivity but low light transmittance. The reason for this is that the filler is completely embedded in the binder layer, and the filler overlaps in the thickness direction of the light diffusion layer to form a multilayer structure. They canceled each other, and the light transmittance was attenuated (light energy was lost). Further, in the conventional light diffuser, problems such as poor dispersion of the filler, agglomeration, sedimentation, and the like are likely to occur, and further, the optical characteristics are easily changed with an increase in the film thickness. there were.

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 it is possible to obtain a light diffuser having high light diffusibility and high light diffusivity, the following production method was attempted.
First, a binder layer is formed on a film, then a filler is attached to the binder layer, and then, using a pressure roller, the filler is embedded in the binder layer, and then excess filler is removed. is there.

However, in this 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, with this method, it was difficult to embed the filler into the binder layer at a uniform depth. That is, 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 layer is embedded deeper than necessary in a place where a large pressure is applied, so that the filler layer is Easy to form multiple layers.

On the other hand, since the filler is not sufficiently embedded in the binder layer in a place where the pressure is small, defects such as filler detachment are liable to occur in a step of washing the excess filler. This phenomenon was noticeable when processing was performed on a large area. Also,
With a filler having a volume average particle diameter of 15 μm or less, the fluidity of the filler is poor, and the pressure of the pressure roller is easily dispersed, so that the filler cannot move on the binder layer, and other fillers are present in the gap between the fillers. Filler cannot be embedded.
For this reason, the filling density of the filler is reduced, and the variation in the filling depth of the filler into the binder layer is increased, making it difficult to obtain uniform diffusivity and permeability.

For the reasons described above, the filler lens manufactured by the above-mentioned manufacturing method partially differs in light diffusivity and light transmissivity, and it has been difficult to industrially use it as a light diffuser. Therefore, the present invention provides a filler lens having high uniformity in light diffusion and light transmission, and excellent in light transmission as compared with a conventional light diffuser having a multilayer filler layer, and a method for producing the same. It is an object.

[0009]

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 a large number of fillers embedded so as to partially protrude from the surface of the deposition layer, wherein the standard deviation of the interparticle distance of the filler in the plane direction of the filler layer is 0. 4 or less. It should be noted that a coating or another layer for improving light diffusion may be formed on the surface of the filler layer.

[0010]

FIG. 1 is a cross-sectional view schematically showing one example of the filler lens of the present invention. The filler lens L is formed by directly laminating a binder layer 2 on a base 1 and embedding a large number of fillers 3 in a surface layer of the binder layer 2 so as to have a high density in a surface direction, thereby forming a filler layer 3A. Are formed.

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 transmission by the filler. The portion is embedded so as to protrude from the surface of the binding layer. Here, the single layer refers to a state in which the filler layer is formed without overlapping the filler. In particular, when a filler lens is used as a light diffuser such as a liquid crystal display,
In the present invention, the standard deviation of the distance between the particles of the filler in the plane direction of the filler layer must be 0.4 or less, since a uniform and uniform one is required. If the standard deviation of the distance between the particles of the filler is larger than 0.4, the light transmittance becomes non-uniform, and practically sufficient light diffusion performance cannot be obtained.

When used in a liquid crystal display or the like, the filler preferably has a volume average particle diameter of 2 to 15 μm. Furthermore, as the particle size distribution of the filler is narrower, the impact force from the pressurized medium can be uniformly transmitted to the filler, so that the filling depth of the filler in the binder layer becomes uniform, and for the same reason. Since the filling density of the filler in the plane direction becomes high and uniform, it is preferably 0.8 to 1.0, more preferably 0.9 to 1.0.

In this specification, the term “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 micrograph of a filler lens. -Volume average particle diameter = First, the diameter of 100 fillers randomly extracted from the micrograph of the filler lens is measured. The filler is regarded as a true sphere from the diameter of the obtained filler, and the volume of each filler is determined. 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.

The term "distance between filler particles" used herein is a value measured by the following method. First, a filler serving as a base point is randomly extracted from a photograph of a filler lens taken vertically from a planar direction. FIG. 2A is a schematic view of a photograph of a filler lens taken perpendicularly from a plane direction. In this figure, the filler Y is a filler serving as a base point for measuring the “distance between filler particles”. Then, a straight line is drawn from the center of the filler Y serving as the base point to the centers of all adjacent other fillers, and the length of the straight line is measured. Next, a value obtained by dividing the length of this straight line by the volume average particle diameter of the filler (here, the volume average particle diameter is X) is defined as the distance between the particles of the filler.

However, at this time, the filler whose straight line comes into contact with another filler, the filler whose size is equal to or less than half of the volume average particle diameter X of the filler, or the filler which overlaps with the other filler is not used. Do not. In addition, fillers having a size equal to or less than half of the volume average particle diameter X of the filler and overlapping fillers are not considered as base fillers.
That is, in FIG. 2A, the filler Y1 and the filler Y
2. The filler Y4 and the filler Y5 are other adjacent fillers. The filler Y3 is a filler Y serving as a base point.
Since the straight line x3 from the center of contacts the filler Y2,
No other filler adjacent. In addition, the fillers Y6 and Y7 have a size equal to or less than half of the volume average particle diameter X of the filler, and therefore are not other adjacent fillers. Further, the fillers Y8, Y9, and Y10 are not other adjacent fillers because the fillers overlap.

Therefore, the “distance between particles of the filler” in the filler Y serving as a base point is determined by the filler Y serving as a base point.
Y1, Filler Y2, Filler Y4 from the center of
And the distance to the center of each of the fillers Y5, and the length of the straight line x1 / X, the length of the straight line x2 /
X, the length of the straight line x4 / X, and the length of the straight line x5 / X are the “distance between the particles of the filler” in the filler Y as the base point.

Further, the "standard deviation of the distance between the particles of the filler" is obtained by measuring the "distance between the particles of the filler" with respect to the 30 base fillers by the above measuring method, and calculating the standard deviation from these values. Ask. However, when measuring the "interparticle distance of the filler" of the 30 base fillers, the filler once identified as the base filler and other adjacent fillers to determine the "interparticle distance of the filler" is once again used. It should not be specified as the base filler and other adjacent fillers. FIG.
In the case of a filler that is not spherical as in (b), the middle point P of the longest diameter x11 of the filler Y11 is set as the center of the filler. In the present specification, as a device for measuring the distance between particles of the filler, 50 to 100 pieces are used for one screen using a transmitted light image photograph of a digital microscope (trade name: VH-6300) manufactured by Keyence Corporation. The one measured at a magnification at which the filler was imaged was used.

In order to uniformly transmit the impact force from the pressurized medium to the filler, the filler is preferably spherical and has a roundness of 85% or more, more preferably 90% or more.
The above is preferred. In the present specification, “roundness” is defined by the following equation. Roundness (%) = (4πA / B ² ) × 100 A: Projected area of filler B: Perimeter of filler The roundness can be determined by, for example, taking an image of the filler with a transmission electron microscope to obtain a projected image. Can be calculated from the above A and B obtained by performing image analysis using an image analyzer (for example, product 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 this specification, the average value measured for 10 fillers is defined as roundness.

The depth of embedding of the filler in the filler layer is such that the exfoliation of the filler from the binder layer is suppressed, and the filler layer protrudes from the surface of the binder layer so that the light diffusion property can be surely exhibited. 10 to 90% of the diameter, preferably 30 to
It is desirable that 80%, more preferably 40 to 70%, be embedded. In the filler lens of the present invention, the filler constituting the filler layer has a refractive index of 1.42-1.
Preferably, it is 55.

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-mentioned structure. At least, a binder layer is formed on a substrate directly or via another layer. It is characterized by comprising a step of laminating, a step of embedding the filler in the binder layer with a pressurized medium, and a step of removing excess filler adhering to the laminate obtained in the step. Further, it is preferable to perform a step of attaching a filler to the surface of the binder layer before the step, since defects in appearance such as removal of the filler are reduced and the filler can be reliably embedded.

In the case where the binder layer contains a curing agent, for example, after the step, a release film is laminated,
The aging treatment may be performed at a temperature of about ℃ for about 3 to 14 days. Furthermore, if a step of applying heat or moisture after the step or afterward to soften the binder layer of the laminate is performed, the filler and the binder layer become familiar, and the total light transmittance is improved. it can. In the step of softening, heat alone or a combination of heat and moisture may be used.

As a specific method of embedding the filler in the binder layer, a spherical material is used as the pressurizing medium, and the pressurizing medium is vibrated so that the pressurizing medium hits the filler and embeds the filler in the binder layer. The form is preferred. According to this method, even when a filler lens having a large area is manufactured, the advantage that the depth of filling of the filler can be made uniform by the pressing medium hitting all over the minute area with a uniform force. Have. At this time, the pressurized medium 100
By mixing about 0.5 to 2.0 parts by weight of filler into parts by weight, another filler is pressed into the gap between the fillers attached to the surface of the binder layer by the impact force of the pressurized medium. This is preferable because the filling density of the filler in the plane direction can be made higher and uniform.

A. Specific Examples of Materials Next, suitable materials used for 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 it allows light to pass therethrough, but when used for a liquid crystal display or the like, the refractive index (JIS K-7142)
Is desirable in the range of 1.45 to 1.55. 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 light transmittance (JIS C-
6714) is 80% or more, more preferably 85%
Those having a haze (JIS K7105) of 3.0 or less, more preferably 1.0 or less, and most preferably 0.5 or less can be suitably used. 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 Furthermore, a lens having a light collecting property or a diffusing property may be formed on one side of the base, and a filler lens may be formed directly or via another layer on the other side of the base.

(2) Binder Layer The binder layer of the present invention is preferably, for example, 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 thereto. The acrylic pressure-sensitive adhesive, acrylic acid and its esters, methacrylic acid and its esters, acrylamide, homopolymers of acrylic monomers such as acrylonitrile or copolymers thereof,
Further, a copolymer of at least one of the above acrylic monomers with an aromatic vinyl monomer such as vinyl acetate, maleic anhydride, and styrene can be used. In particular, ethylene acrylate, butyl acrylate, and main monomers such as 2-ethylhexyl acrylate that exhibit adhesiveness, vinyl acetate and acrylonitrile as cohesion components,
Monomers such as acrylamide, styrene, methacrylate, and methyl acrylate, as well as methacrylic acid, acrylic acid, and itaconic acid for improving the adhesive strength and imparting a crosslinking starting point,
A copolymer comprising a functional group-containing monomer such as hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, acrylamide, methylolacrylamide, glycidyl methacrylate, and maleic anhydride, and having a Tg (glass transition point) of- 60 to -15
C. and those having a weight average molecular weight in the range of 200,000 to 1.2 million are preferred.

A binder layer comprising an adhesive having a Tg lower than -60 ° C. or an adhesive having a weight-average molecular weight of less than 200,000 is too soft. And other defects are likely to occur. Further, an adhesive is adhered to the filler once peeled off, and the filler may adhere to the filler layer again. Furthermore, in the binder layer which is too soft, the part where the filler adhesive adheres appears on the surface of the filler layer by the filler rotating in the vertical direction on the surface of the binder layer due to the impact of the pressurized medium, and other parts there. The filler may adhere, or the pressure-sensitive adhesive may seep out from the gap between the fillers due to the impact force of the pressurized medium or the capillary phenomenon, and other 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 of 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 filler is liable to drop off in a step of washing excess filler due to insufficient tackiness.

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, and if the adhesive strength is less than 100 g / 25 mm, the removal of the filler occurs or the environmental resistance is deteriorated. In particular, under high temperature and high humidity, the binder layer may peel off from the transparent substrate. Further, the holding force (JIS Z 023711) of the adhesive is preferably 0.5 mm or less. If the holding force is larger than 0.5 mm, the filler layer is soft, so that the filler layer is likely to be a multilayer as described above. Further, a UV-curable pressure-sensitive adhesive to which a photopolymerizable monomer, oligomer, polymer and photopolymerization initiator are added may be used as the pressure-sensitive adhesive.

(3) Filler As the filler of the present invention, inorganic fillers such as silica and alumina, acrylic resin, polystyrene resin, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, Teflon, divinylbenzene, phenol resin, urethane resin Organic fillers such as resin, cellulose acetate, nylon, cellulose, benzoguanamine, and melamine can be used, but organic fillers are preferable from the viewpoint of light transmittance and adhesion to the binder layer, and acrylic is more preferable in terms of light resistance. Beads and silicone beads are particularly preferred. 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 drop off during the filler embedding step or the washing step, and the fillers are liable to be removed.

The filler is preferably spherical as described above, and has a volume average particle diameter of 1 to 50.
It can be used for a liquid crystal display or the like, but it is preferably 2 to 15 μm.
More preferably, it is 10 μm to 10 μm. 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 contrast of the liquid crystal cell is undesirably reduced. On the other hand, in the case of a filler larger than 15 μm, the edge portion of the liquid crystal image is blurred and the visibility is reduced, and the gap between the filler portion and the filler, that is, the high light diffusion portion and the low light diffusion portion are visually observed. And the uniformity is lowered, which is not preferable.

Further, in order to make the filling density of the filler layer in the plane direction high and uniform and to make the filling depth of the filler into the binder layer uniform, the impact force of the pressurized medium is uniformly applied to the filler. It is necessary to convey, and for that purpose, the particle size distribution of the filler is preferably in the range of 0.8 to 1.0, and more preferably in the range of 0.9 to 1.0. For the same reason, the filler is preferably spherical, and its roundness is preferably 85% or more, more preferably 90% or more. In addition, the refractive index of the filler is preferably close to the refractive index of the base material and the binder layer, and is preferably in the range of 1.42 to 1.55 because high light transmittance can be obtained. .

(4) Other Layers As other layers, an adjusting layer for adjusting the refractive index and transmittance of light, or an adhesive layer for firmly bonding the base and the binding layer may be provided. Good.

B. 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, coating such as electrodeposition coating, dip coating, die coating, relief 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.

When the binder layer contains a curing agent component, the binder layer is protected by a peelable PET film or the like, and aged at a temperature of about 20 to 80 ° C. for about 3 to 14 days. The reaction may proceed to the next step after reacting the agent with the curing agent.

[Step 2: Attachment of Filler to Binder Layer Surface] Next, it is desirable to attach a filler to the surface of the binder layer on the substrate in advance. As the method, for example, a method in which a filler filled in a container is fluidized by vibration or fluidizing air, a substrate is passed through the fluidized filler, or a filler is sprayed on the binder layer by air spray. No. By adhering the filler to the surface of the binder layer, defects such as filler detachment are reduced, and the pressure medium adheres to the binder layer in the step of embedding the filler into the binder layer by a later pressurized medium. It can also be prevented. In this step, the filler only needs to adhere to the surface of the binder layer by the adhesive force of the binder layer.

[Step 3: Embedding Filler in Binder Layer] The filler adhered to the surface of the binder layer is embedded in the binder layer by the impact of a 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 a filler is attached to the surface of the binder layer is charged or passed through the medium. This gives an impact force to the filler. Then, the filler is hit by the pressurized medium and is embedded in the surface layer of the binder layer. Since the pressurized medium can apply a uniform impact to the filler in a small area, the filler can be embedded in the binder layer with a uniform embedding depth. At this time, the pressurized medium 10
When a pressurized medium in which about 0.5 to 2.0 parts by weight of filler is mixed in advance with respect to 0 part by weight is used, another filler is pressed into the gap of the filler attached to the surface of the binder layer in the previous step. Since it can be pushed in by the impact force of the medium, it is preferable because the filling density of the filler can be made higher and uniform. By such a method, the filler protrudes from a part of the binding layer in a state in which the filling depth is uniform, and is uniformly and densely embedded in the whole, and in a single layer state without being laminated in the binding layer. It is formed as a filler layer.

As the external force applied for embedding the filler, rotation, dropping, etc. may be adopted 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. Various metals,
Alloys, or Al ₂ O ₃ , SiO ₂ ,
Those made of ceramics such as TiO 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 diameter of the pressurized medium is appropriately selected depending on the material of the filler and the depth of embedding of the filler, but is preferably about 0.3 to 2.0 mm.

[Step 4: Removal of Excess 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 excess filler can be removed by applying fluid pressure to the filler layer by washing with water, air blowing, or the like. At this time, when the volume average particle diameter of the filler is 2 to 15 μm, since removal by fluid pressure is likely to be insufficient, an aqueous solution such as ion-exchanged water to which a cleaning aid such as a surfactant is added is used. It is preferable to perform ultrasonic cleaning or the like.

[0039]

Next, an embodiment of the present invention will be described. A. Preparation of Acrylic Polymer a In a flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet tube, 94 parts by weight of n-butyl acrylate, 3 parts by weight of acrylic acid, 1 part by weight of 2-hydroxyacrylate, and 0.1 part by weight of benzoyl peroxide. 3 parts by weight, 40 parts by weight of ethyl acetate,
After adding 60 parts by weight of toluene, nitrogen was introduced from a nitrogen introduction tube to make the inside of the flask a nitrogen atmosphere.
And a polymerization reaction was performed for 10 hours to obtain an acrylic polymer solution having a weight average molecular weight of about 1,000,000 and a Tg of about -50 ° C. 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.

B. Production of Filler Lens <Example 1> As a transparent substrate, triacetyl cellulose having a thickness of 80 μm (trade name: Fujitack UVD80, refractive index 1.49, total light transmittance 92.4, haze 0.15,
Fuji Photo Film Co., Ltd.). On one side of this film, 0.45 parts by weight of an isocyanate-based curing agent (trade name: L-45, manufactured by Soken Chemical Co.) and 100 parts by weight of an epoxy-based curing agent (trade name: E based on 100 parts by weight of acrylic polymer a)
-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 to form a binder layer. Then, this film was cut into the size of A5 plate.

Next, as a filler, a methyl silicone filler having a volume average particle size of 4.5 μm, a particle size distribution of 0.94, a refractive index of 1.43, and a roundness of 96% (trade name: Tospearl 145, GE Toshiba Silicone Co., Ltd.) The filler was put into a perforated plate container from which air was blown out 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 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, a filler was buried in the surface layer of the binding 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 a bowl 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 into the container C of the vibrating apparatus as a pressurizing medium, and 30 g of the above-mentioned silicone-based filler was further charged and mixed. Next, the vibrating device was moved to the container C as shown in FIG.
The film is moved at a speed of 30 cm / min while the container C is vibrated while being tilted at 45 degrees from the state shown in FIG. This caused it to pass through the pressurized medium. As a result, the filler was hit with a vibrating pressurized medium and embedded in the surface layer of the binder layer to form a filler layer.

Next, the filler lens is immersed in a 0.1% aqueous solution obtained by adding a surfactant (trade name: Liponox NC-95, manufactured by Lion Corporation) to ion-exchanged water, and ultrasonic waves are applied. Excess filler was washed away, rinsed sufficiently with ion-exchanged water, and the surface was drained with an air knife. Then, after leaving it to stand in a constant temperature bath at 40 ° C. for 7 days, it was dried and cooled to room temperature to obtain a filler lens of Example 1.

<Example 2> The adhesive of Example 1 was coated on one surface of a transparent substrate film similar to that of Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. In the subsequent steps, the filler to be used was changed to a volume average particle size of 10.8 μm and a particle size distribution of 0.9.
4, except that the refractive index was changed to 1.50 and methyl methacrylate having a roundness of 94% (trade name: MX-1000, manufactured by Soken Chemical Co., Ltd.). Obtained.

<Example 3> The adhesive of Example 1 was coated on one surface of the same transparent substrate film as in Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. In the subsequent steps, the filler to be used was subjected to a volume average particle diameter of 14.9 μm and a particle diameter distribution of 0.9.
6, except that the refractive index was changed to 1.50 and methyl methacrylate having a circularity of 92% (trade name: MX-1500H, manufactured by Soken Chemical Co., Ltd.). Obtained.

Comparative Example 1 The adhesive of Example 1 was coated on one surface of the same transparent substrate film as in Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. Next, the filler used in Example 1 was attached to the binder layer in the same manner as in Example 1. Next, YB
The surface was leveled using an A-type baker applicator (manufactured by Yoshimitsu Seiki Co., Ltd.) such that the thickness of the filler adhered layer was 12.5 μm. Then, a pressure roller (trade name: Lam)
ipacker PD3204, Fujipla In
c. The film to which the filler was attached was inserted into the pressure roller at a speed of 1.5 cm / sec by using the above method, and the filler was embedded in the binder layer. The subsequent steps were performed in the same manner as in Example 1 to obtain a filler lens of Comparative Example 1.

Comparative Example 2 The adhesive of Example 1 was coated on one surface of the same transparent substrate film as in Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. Next, the filler used in Example 1 was adhered to the binder layer in the same manner as in Example 1, and the thickness of the filler-adhered layer was reduced to 1 using a YBA type baker applicator.
The surface was leveled to 2.5 μm. When inserted into the pressure roller in the next step, the base material with the filler
The pressure of the roller was increased by sandwiching the laminated PET film having a thickness of 125 μm, and the filler was embedded in the binder layer. Subsequent steps are performed in the same manner as in Example 1.
A filler lens of Comparative Example 2 was obtained.

Comparative Example 3 The adhesive of Example 1 was coated on one surface of the same transparent substrate film as in Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. Next, using the filler of Example 2, the surface was leveled by changing the gap of the YBA type baker applicator so that the thickness of the filler adhering layer became 25 μm. The subsequent steps were performed in the same manner as in Comparative Example 1 to obtain a filler lens of Comparative Example 3.

Comparative Example 4 The adhesive of Example 1 was coated on one surface of the same transparent substrate film as in Example 1 with a reverse coater so that the thickness after drying was 5 μm.
After drying at 2 ° C. for 2 minutes to form a binder layer, the film was cut into A5 plates. Next, using the filler of Example 3, the surface of the YBA-type baker applicator was changed by changing the gap so that the thickness of the filler adhering layer was 25 μm. The subsequent steps were performed in the same manner as in Comparative Example 1 to obtain a filler lens of Comparative Example 4.

<Comparative Example 5> 10 parts by weight of the filler used in Example 1 was added to 100 parts by weight of the solid content of the pressure-sensitive adhesive used in Example 1, and the mixture was stirred for 1 hour with agitase to prepare a paint. did. The prepared paint was applied on one surface of the same transparent substrate film as in Example 1 with a comma coater so that the thickness after drying was 25 μm, and dried to form a filler layer. A release PET film (trade name: 3811, manufactured by Lintec Corporation) was laminated on the surface of the filler layer,
After being left in a thermostat at 0 ° C. for one week, it was cooled to room temperature. After that, cut into A5 plates, peel off the release PET,
A filler lens of Comparative Example 5 was obtained.

C. Evaluation of Filler Lens-Observation of Filler Lens The planes and cross sections of the filler lenses of Examples 1 to 3 and Comparative Examples 1 to 5 obtained by the above method were observed with an electron microscope. FIG. 4 is a photomicrograph taken at 1000 times of the plane and cross section of the filler lens of Example 1.
(A) shows a plane and (b) shows a cross section. 5 and 6 show the plane (a) and cross section (b) of the filler lenses of Examples 2 and 3 at 500 times magnification, and FIGS. 7 and 8 show the plane (a) and cross section (b) of the filler lenses of Comparative Examples 1 and 2. 9) is 1000 times, FIGS. 9 and 10 are 500 times the plane of the filler lens of Comparative Examples 3 and 4, and FIG. 11 is 1000 times the plane (a) and cross section (b) of the filler lens of Comparative Example 5. 5 is an electron micrograph taken in FIG.

As can be seen from the plan photographs shown in FIGS. 4 to 6A, the filler lenses of Examples 1 to 3 have a high packing density in the surface direction and are uniform. According to the cross-sectional photograph of b), in the filler lenses of Examples 1 to 3, the filler layer is a single layer, and the filler is embedded at a uniform depth in a configuration in which a part of the filler protrudes from the surface of the binding layer. It was shown that. On the other hand, in the filler lenses of Comparative Examples 1 to 4 in which the filler was embedded in the binder layer by a roller, as shown in the plan photographs of FIGS. In Examples 1 and 2, it became clear that a region (a1) where the filler was filled densely and a region (a2) where the filler was filled were generated. In the region where the filling density of the filler is high, as is clear from the cross-sectional photographs shown in FIGS.
There were many sites having a structure like a colony in which another filler adhered to the binder layer exposed from the gap of the first filler. This is considered to be because a high pressure was applied to this portion, the first-layer filler was deeply embedded in the binder layer, and another filler adhered to the binder layer extruded into the gap between the fillers.

In Comparative Example 5 which is a conventional filler lens, as shown in FIG. 11A, the filler is completely buried in the binder layer. According to the results, it was observed that the filler was present in the binder layer in the multiple layers.

FIG. 12 is an optical microscope photograph (magnification: 50) of a state where transmitted light is used for the filler lenses of Example 1 and Comparative Example 1. As is clear from the optical micrograph, the filler lens of Example 1 in which the filler burying depth was uniform showed that the light transmittance was uniform.
On the other hand, in the filler lens of Comparative Example 1 in which the filling depth of the binding layer of the filler was uneven and the filler partially overlapped, the light transmittance was shown to be uneven.

Measurement of distance between filler particles The distance between fillers in the surface direction of the filler lenses of Examples 1 to 3 and Comparative Examples 1 to 5 was measured by a digital microscope (trade name: VH-6300) manufactured by KEYENCE CORPORATION. . 3000 times for a filler lens using a filler having a volume average particle diameter of less than 10 μm, and 1000 for a filler lens using a filler having a volume average particle diameter of 10 μm or more.
At twice the magnification, the distance between the particles of the filler was measured using transmitted light, and the standard deviation was calculated.

Optical property test For the filler lenses of Examples 1 to 3 and Comparative Examples 1 to 5, total light transmittance when light is incident from the filler side as shown in FIG. 13: Tt (%), Light diffusivity: H
z (%) was measured using a spectrophotometer UV3100 manufactured by Shimadzu Corporation.

Evaluation of Uniformity of Light Transmittance and Diffusivity The filler lenses of Examples 1 to 3 and Comparative Examples 1 to 5 were visually observed through transmitted light to evaluate the uniformity of light transmittance. . The case of uniform was evaluated as ○, and the case where there was a bright spot (transparency) where the transmittance was abnormally high in some places or a dark spot where the transmittance was low was evaluated as ×, and the uniformity of light transmittance and diffusion was evaluated. The results are shown in Table 1.

[0059]

[Table 1]

As is clear from Table 1, the standard deviation of the distance between the particles of the filler in the filler lenses of Examples 1 to 3 is 0.4 or less, whereas the standard deviation of Comparative Examples 1 to 4 is 0.1. The value was larger than 4. In the filler lens of Comparative Example 5, since the filler was completely buried in the binder layer, it was impossible to focus with an optical microscope using transmitted light, and the distance between filler particles could not be measured. Was.

The filler lenses of Examples 1 to 3 and Comparative Examples 1 to 4 having the structure shown in FIG. 1 are different from the filler lens of Comparative Example 5 of the conventional type having a multilayered filler layer as shown in FIG. However, since the total light transmittance is high despite the high total light diffusivity, it can be said that the light transmittance and the light diffusivity are excellent. Further, the filler lenses of Examples 1 to 3 have a higher filling density of the filler than the filler lenses of Comparative Examples 1 to 4, are uniform, and have a uniform single-layer structure. And the total light diffusivity is high.

Due to the above characteristics, for example, when the filler lens of the present invention is used in a transmission type liquid crystal display, the filler lens is interposed between the backlight unit 12 and the liquid crystal cell 14 held between the polarizing plates 13 as shown in FIG. When the lens 11 is inserted or the film surface is subjected to adhesive processing as shown in FIG. 15 to provide an adhesive layer 15 and the filler lens 11 and the deflecting plate 13 are bonded together, the light of the backlight unit 12 is used. Can be efficiently transmitted, and light can be efficiently diffused. Therefore, since the attenuation of the incident light is small, it is possible to reduce the battery consumption while obtaining the conventional light amount, and to secure a high viewing angle. Further, 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, and the contrast of the liquid crystal display can be improved, which is preferable.

[0063]

As described above, the filler lens of the present invention has a single-layered filler layer on the surface of the binder layer laminated on the base, with a part protruding from the surface of the binder layer. Since the layer is formed and the filling density of the filler in the planar direction of the filler layer is high and uniform, a filler lens having higher and more uniform light transmission and diffusion performance than the conventional filler lens can be obtained. 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 diagram illustrating a distance between particles of a filler.
(A) is a schematic diagram of a photograph of a filler lens taken vertically from a planar direction, and (b) is a schematic diagram of a non-spherical filler.

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

FIG. 4 is a micrograph showing a plane (a) and a cross section (b) of the filler lens of Example 1 of the present invention at a magnification of 1000 times.

FIG. 5 is a photomicrograph showing a plane (a) and a cross section (b) of a filler lens of Example 2 of the present invention at a magnification of 500 times.

FIG. 6 is a photomicrograph showing a plane (a) and a cross section (b) of a filler lens of Example 3 of the present invention at a magnification of 500 times.

FIG. 7 is a photomicrograph showing the plane (dense area (a1), rough area (a2)) and cross section (b) of the filler lens of Comparative Example 1 of the present invention at a magnification of 1000 times.

FIG. 8 is a photomicrograph showing the plane (dense region (a1), rough region (a2)) and cross section (b) of the filler lens of Comparative Example 2 of the present invention at a magnification of 1000 times.

FIG. 9 is a photomicrograph showing a plane of a filler lens of Comparative Example 3 of the present invention at a magnification of 500 times.

FIG. 10 is a micrograph showing a plane of a filler lens of Comparative Example 4 of the present invention at a magnification of 500 times.

FIG. 11 is a micrograph showing a plane (a) and a cross section (b) of a filler lens of Comparative Example 5 of the present invention at a magnification of 1000 times.

FIG. 12 is an optical microscope photograph of a plane of a filler lens of Example 1 and Comparative Example 1 of the present invention taken with a 50 × objective lens using transmitted light.

FIG. 13 is a schematic diagram for explaining the direction of incident light with respect to a filler lens.

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

FIG. 16 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.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Riki Murata 3-1 Yomiba-cho, Shizuoka-shi, Shizuoka Prefecture F-term in the Information Media Division of Hamakawa Paper Mills Co., Ltd. 2H042 BA02 BA15 BA20 2H091 FA26Z FA31Z FB02 FB06 FC18 FC22 FD03 FD18 GA17 LA17 LA18 LA19

Claims (10)

[Claims] 1. A base, a binder layer laminated on the base directly or via another layer, and a number of fillers embedded in a state where the filler protrudes partially from the surface of the binder layer. And a standard deviation of a distance between particles of the filler in a plane direction of the filler layer is 0.4 or less. 2. 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. 3. The filler has a volume average particle diameter of 2 to 3.
The filler lens according to claim 1, wherein the thickness of the filler lens is 15 μm. 4. The filler lens according to claim 1, wherein the filler has a spherical shape, and has a roundness of 85% or more. 5. The filler has a refractive index of 1.42 to 1.42.
The filler lens according to any one of claims 1 to 4, wherein the ratio is 1.55. 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 method for producing a filler lens according to claim 1, wherein at least the step of laminating the binder layer directly or via another layer on the substrate. And a step of embedding a filler in the binder layer with a pressurized medium; and a step of removing excess filler attached to the laminate obtained in the step. 8. A method for producing a filler lens according to claim 1, wherein at least the step of laminating the binder layer directly or via another layer on the substrate. And a step of attaching the filler to the surface of the binder layer, a step of embedding the filler in the binder layer with a pressurized medium, and a step of removing excess filler attached to the laminate obtained in the step. A method for producing a filler lens, characterized by comprising: 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. 9. The method for producing a filler lens according to 7 or 8. 10. The method for producing a filler lens according to claim 7, wherein in the step of removing the surplus filler, the removal is performed using water or an aqueous solution.