JP3630396B2 - Manufacturing method of filler lens - Google Patents

Description

【００４４】
表１によれば、フィラーを樹脂中に分散させた比較例１においては、光がフィルム側とフィラー側のいずれから入射しても、全光線拡散透過率は約９１％、全光線拡散反射率は約２６％と差はみられなかった。一方、実施例１，２および比較例２の光散乱性は、光の入射方向がフィルム側からとフィラー側からとで差が認められた。光がフィルム側から入射する場合には、全光線拡散透過率が比較例１より低いが、全光線拡散反射率は高く、また、光がフィラー側から入射する場合には、全光線拡散透過率がきわめて高く、逆に全光線拡散反射率は低かった。
【００４５】
また、高温高湿下に放置後、実施例１，２および比較例１の光散乱性には、ほとんど変化が見られなかったが、結着層の粘着剤を硬化させていない比較例２については、光がフィルム側から入射する場合の全光線拡散透過率が上昇し、一方、全光線拡散反射率が低下した。すなわち、本発明の製造法によれば、光の入射方向が表裏いずれであるかによって光散乱性が異なるレンズ効果が認められ、かつ高温高湿下においても特定の光散乱性を保持し続けるフィラーレンズを得ることが可能である。
【００４６】
例えば、透過型の液晶ディスプレイに用いる場合、図９（ａ）に示すように、液晶パネル２０とバックライト２１との間に、光拡散板として、本発明のフィラーレンズＬのフィルム１を液晶パネル２０側に向けて配置すると、バックライト２１の光の透過率がきわめて高く、これに加えてディスプレイの前面側（図で上側）から入射する太陽光や電灯光は反射しやすい状態となる。したがって、液晶パネル２０を照明する光量がきわめて多くなり、液晶画像の鮮明化ならびに節電効果を得ることができる。また、図９（ｂ）に示すように、液晶パネル２０の前面側にフィルム１を前方に向けて配置すると、バックライト２１の透過率が高いことから、視野角がきわめて広い光拡散レンズとして使用することができる。
【００４７】
【発明の効果】
以上説明したように、本発明によれば、結着層の表面から一部が突出する状態にフィラーを結着層表層に埋め込んであるため、フィラーのレンズ効果が十分発現され、さらに、結着層の粘着剤が硬化していることから、この光学特性を高温高湿条件下においても保持し続けるフィラーレンズの製造方法を提供することができる。
【図面の簡単な説明】
【図１】本発明のフィラーレンズの一例を模式的に示す断面図である。
【図２】本発明のフィラーレンズを製造するにあたって好適な加振装置の正面断面図である。
【図３】本発明の実施例１のフィラーレンズの平面を（ａ）１０００倍、（ｂ）２０００倍、（ｃ）５０００倍で示す顕微鏡写真である。
【図４】本発明の実施例１のフィラーレンズの断面を（ａ）２０００倍、（ｂ）５０００倍で示す顕微鏡写真である。
【図５】本発明の実施例２のフィラーレンズの平面を（ａ）１０００倍、（ｂ）２０００倍、（ｃ）５０００倍で示す顕微鏡写真である。
【図６】本発明の実施例２のフィラーレンズの断面を（ａ）２０００倍、（ｂ）５０００倍で示す顕微鏡写真である。
【図７】フィラーレンズに対する光散乱性を説明するための図であって、全光線拡散透過率と全光線拡散反射率を示す模式図である。
【図８】光散乱性の測定方法を説明するための図であって、（ａ）全光線拡散透過率、（ｂ）全光線拡散反射率の測定方法を示す模式図である。
【図９】（ａ）、（ｂ）はそれぞれ本発明のフィラーレンズを液晶ディスプレイに適用した例を模式的に示す断面図である。
【図１０】従来のフィラーレンズの一例を模式的に示す断面図である。
【符号の説明】
１…フィルム（基体）、２…結着層、３…フィラー、３Ａ…フィラー層、Ｌ…フィラーレンズ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a filler lens that is suitably used for displays such as LCD, EL, FED, and the like, and in particular, exhibits excellent effects in preventing luminance unevenness and improving contrast in these displays.
[0002]
[Prior art]
In recent years, displays such as LCD, EL, and FED have been remarkably developed. In particular, LCDs are widespread in various fields such as notebook personal computers and portable terminals, and there are high expectations for the future. This LCD is divided into a reflective type and a transmissive type by taking in light to illuminate the liquid crystal panel.BroadIs done. In the reflective type, a reflective plate with a highly reflective aluminum film or the like is disposed on the back surface of the liquid crystal panel, and external light incident from the display surface side is reflected by the reflective 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 the liquid crystal panel is illuminated by a backlight unit disposed on the back surface of the liquid crystal panel. In the reflective type, the background color is paper white with a medium that diffuses light appropriately between the liquid crystal panel and the reflector to prevent the aluminum ground color from deteriorating the contrast. It is done to approach. A transmissive backlight unit generally includes a light source such as an acrylic light guide plate having a cold cathode tube and a light diffusing plate that diffuses the light from the light source. It is configured to illuminate.
[0003]
As described above, a light diffusing medium (hereinafter referred to as a light diffuser) is generally used regardless of whether the reflection type or the transmission type is used. Examples of the light diffuser include a laminate of a binder resin in which a light diffusing filler is dispersed on one surface of a transparent resin film. Such a conventional light diffuser has been manufactured by a method in which a filler is dispersed in a solution in which a solvent is mixed with a binder resin to form a paint, and this paint is applied on a film with a spray or a coater. FIG. 10 schematically shows a light diffuser obtained by such a manufacturing method. A binding layer 2 in which a binder resin solution is cured is formed on the film 1, and the binding layer 2 is formed in the binding layer 2. Filler 3 is dispersed.
[0004]
The total light diffusing transmittance and total light diffusing reflectance of the above-mentioned conventional light diffuser show almost the same value with no significant difference in the direction of incident light between the filler side and the film side. It can be seen that the light diffusivity is the same, that is, there is no directivity regardless of the incident direction of light. The reason for this is that the filler is completely embedded in the binder layer, and the filler is overlapped in the thickness direction to form a multilayer, or the surface shape is rough when the packing density of the filler is rough. For example, it becomes a relatively sine curve (sine curve).
[0005]
[Problems to be solved by the invention]
Therefore, the present inventors have intensively studied to produce a filler lens having a structure in which a filler is embedded so that a part of the surface of the binder layer protrudes and the protruding filler becomes a fine lens. As a result, a method of embedding the filler in the binder layer by hitting the filler with an external force through a pressurized medium has been developed, and a filler lens that exhibits directional light diffusivity has been produced.
[0006]
However, in the above filler lens, since the adhesive of the binder layer is held in a flexible state when the filler is embedded, the filler is embedded by heat flow of the adhesive, particularly under high temperature and high humidity. The state has changed, and it has been difficult to maintain the reliability of optical characteristics, that is, specific optical characteristics.
[0007]
Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing a filler lens in which the lens effect of the filler is sufficiently expressed and this optical property is maintained even under high temperature and high humidity conditions. It is said.
[0008]
[Means for Solving the Problems]
The method for producing a filler lens of the present invention includes a base, a binding layer containing at least a radiation curable resin laminated directly or via another layer on the base, and a surface layer of the binding layer. A method for producing a filler lens comprising a filler layer embedded in a state in which a part protrudes from the surface of the adhesion layer, wherein the binder layer is laminated on the substrate directly or via another layer When,GranularA step of embedding the filler in the binder layer by applying an external force through the pressurizing medium, a step of curing the binder layer, and a step of removing excess filler adhering to the laminate obtained in the above step It is characterized by comprising. As a specific method of embedding the filler in the binder layer, a form in which the pressurized medium strikes the filler and embeds it in the binder layer by vibrating the granular pressurized medium can be mentioned.
[0009]
According to the method for manufacturing a filler lens of the present invention, the filling depth of the filler is made uniform, the filler is arranged in a high density in the surface direction, a single layer is formed on the surface of the binding layer, and a part of the filler is the binding layer. It is possible to manufacture a filler lens having a configuration embedded so as to protrude from the surface. Furthermore, since the adhesive of the binder layer in which the filler is embedded is cured in this filler lens, the thermal characteristics of the adhesive do not occur even under high temperature and high humidity conditions, and the optical characteristics of the filler lens are improved. It can be kept constant.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view schematically showing an example of a filler lens obtained by the manufacturing method of the present invention. In this filler lens L, the binder layer 2 is directly laminated on the substrate 1, and a large number of fillers 3 are formed as a single layer on the surface layer of the binder layer 2 and partially protrude from the surface of the binder layer 2. Further, the filler layer 3A is formed by being embedded so as to have a high density in the surface direction.
[0011]
Hereinafter, the constituent material and manufacturing method suitable for the filler lens obtained by the present invention will be described.
A. Constituent material
(1) Base
As the substrate used in the present invention, a known transparent film can be used. Specifically, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), triacetyl cellulose (TAC), polyarate, polyimide, polyether, polycarbonate, polysulfone, polyethersulfone, cellophane, aromatic polyamide, polyethylene, polypropylene, Various resin films made of polyvinyl alcohol or the like can be suitably used. The substrate of the present invention is not limited to such a film, and a sheet-like member made of a glass material such as quartz glass and soda glass can be used in addition to the hard plate made of the resin and the resin plate.
[0012]
The substrate may be a non-transparent material as long as it transmits light. However, when used in a liquid crystal display, the refractive index (JIS K-7142) is 1.45 to suit the refractive index. A transparent substrate in the range of 1.55 is desirable. Specific examples include acrylic resin films such as triacetyl cellulose (TAC) and polymethyl methacrylate. The higher the transparency of these transparent substrates, the better. However, the light transmittance (JIS C-6714) is 80% or more, more preferably 90% or more, and the haze (JIS K7105) is 1.0 or less. More preferably, it is 0.5 or less. When the transparent substrate is used for a small and light liquid crystal display, the transparent substrate is more preferably a film. Regarding the thickness of the transparent base material, it is desirable that the thickness is thin from the viewpoint of weight reduction, but considering the productivity, it is preferable to use a material having a thickness in the range of 1 to 5 mm.
[0013]
(2) Binder layer
The binder layer in the present invention contains at least a radiation (ultraviolet ray, electron beam, etc.) curable resin. A curing agent such as a crosslinking agent and a polymerization initiator, a polymerization accelerator, a solvent, a viscosity modifier and the like can be added to such a resin as necessary, and these may be used alone or in combination..
[0014]
Specific examples of radiation curable resins include polyester resins, polyether resins, acrylic resins, epoxy resins, alkyd resins, polybutadiene resins, spirol acetal resins, urethane resins, polyfunctional compounds (meth) acrylates such as polyhydric alcohols. Examples of such oligomers or prepolymers and reactive diluents include monofunctional monomers and polyfunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. In particular, an acrylic resin is preferable because it has good transparency, is excellent in water resistance, heat resistance, light resistance, and the like, has an adhesive force, and when used in a liquid crystal display, the refractive index can be easily adjusted to suit it.
[0015]
A thermosetting resin can be used for the binder layer in order to adjust the adhesive force and the like. Thermosetting resins include acrylic resin, phenol resin, melamine resin, polyurethane resin, urea resin, diallyl phthalate resin, guanamine resin, unsaturated polyester resin, amino alkyd resin, melamine-urea co-condensation resin, guanamine resin, silicon resin Polysiloxane resin or the like can be used. Among these, acrylic resins are particularly preferable from the viewpoints of adhesive strength, viscosity adjustment of paint, transparency and the like. Specific examples include acrylic acid and esters thereof, methacrylic acid and esters thereof, homopolymers or copolymers of acrylic monomers such as acrylamide and acrylonitrile, and at least one of the acrylic monomers, vinyl acetate, Mention may be made of copolymers with aromatic vinyl monomers such as maleic anhydride and styrene. In particular, main monomers such as ethylene acrylate, butyl acrylate, and 2-ethylhexyl acrylate that exhibit adhesiveness, monomers such as vinyl acetate, acrylonitrile, acrylamide, styrene, methacrylate, and methyl acrylate, which are cohesive components, Contains functional groups such as methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminomethyl methacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, maleic anhydride, etc. It is a copolymer composed of monomers, Tg (glass transition point) is in the range of −60 to −15 ° C., and the weight average molecular weight is in the range of 200,000 to 1,000,000. Preference is. When Tg is −60 ° C. or lower, the binder layer is too soft, and the embedded filler layer is easily damaged. When Tg is −15 ° C. or higher, embedding of the filler is deteriorated.Further, when the substrate is a plastic film, the curing temperature cannot be set high. In particular, when PET or TAC is used, it is desirable that the cured resin to be used can be cured at 100 ° C. or lower.
[0016]
In order to cure the radiation curable resin used in the present invention, for example, irradiation with ultraviolet rays, electron beams, X-rays or the like may be performed. However, when curing with ultraviolet rays, it is necessary to add a photopolymerization initiator. As a photopolymerization initiator, benzophenones, α-amyloxime ester, Michler benzoyl benzoate, tetramethylthiuram monosulfide, thioxanthones can be mixed and used, and as a photosensitizer, n-butylamine, Triethylamine or the like can also be mixed and used. The content of the photopolymerization initiator is preferably in the range of 0.1 to 10% by weight with respect to the radiation curable resin. Even if it is more or less than this range, the effect becomes worse. Further, as the curing agent for the thermosetting resin, for example, a metal chelate-based, isocyanate-based, or epoxy-based crosslinking agent may be used alone or in combination as required.
[0017]
In the present invention, the adhesive strength (180 degree peel adhesive strength according to JIS Z0237) of the binder layer before curing the radiation curable resin is 50 to 3000 g / 25 mm, and the adhesive strength after radiation curing is 30 g / 25 mm or less. It is practically preferable that they are blended as described above. When the adhesive strength before curing is less than 50 g / 25 mm, the filler becomes difficult to be embedded or the embedded filler is detached. On the other hand, when the adhesive strength exceeds 3000 g / 25 mm, the filler is embedded excessively, or the surface of the formed filler layer is likely to be damaged or indented. Further, if the adhesive strength after curing exceeds 30 g / 25 mm, the filler layer surface is likely to be scratched or indented, and the environmental resistance is poor, and in particular, the optical properties change under high temperature and high humidity. There is a fear.
[0018]
(3) Filler
As the filler, use an inorganic transparent or white pigment such as silica or alumina, an organic transparent or white pigment such as acrylic resin, polystyrene resin, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, or Teflon. Can do. In particular, silica, acrylic beads, and silicone beads are preferable. The filler is preferably spherical, and its roundness is 80% or more, more preferably 90% or more. Spherical fillers also have the merit that variations in embedding depth hardly occur. The average particle size (JIS B9921) is preferably 1 to 50 μm, more preferably 3 to 30 μm, and even more preferably 3 to 9 μm. In order to obtain a good lens effect, it is better that the particle size distribution is narrow, and the best effect is obtained at the time of monodispersion.
[0019]
In addition, when used for a liquid crystal display or the like, the refractive index of the filler is preferably in the range of 1.45 to 1.55 for the suitability of the refractive index, and further, the refractive index of each of the substrate, the binder layer and the filler. Is preferably 0.30 or less, and more preferably 0.15 or less.
[0020]
In this specification, “roundness” is defined by the following general formula (1).
Roundness = 4πA / B²  ... (1)
A: Projection area of filler particles
B: Perimeter length of filler particles
This roundness was obtained, for example, by photographing a filler particle with a transmission electron microscope to obtain a projection image, and analyzing the image using an image analysis apparatus (for example, product name: EXECLII manufactured by Nippon Avionics Co., Ltd.). It can be calculated from the above A and B. As is apparent from the above equation, the roundness is close to 1 when the particle is close to a true sphere, and is smaller than that when the particle is indefinite.
[0021]
(4) Other layers
As another layer, an adjustment layer for adjusting the refractive index and transmittance of light, an adhesive layer for firmly bonding the substrate and the binder layer, or the like may be provided.
[0022]
B. Production method
Next, the specific example of the manufacturing method of the filler lens of this invention is shown.
"Step 1: Lamination of binder layer"
Apply the above adhesive directly or through other layers on one or both sides of the substrate, air doctor coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray Coating, slot orifice coating, calendar coating, electrodeposition coating, dip coating, die coating, etc., relief printing such as flexographic printing, intaglio printing such as direct gravure printing, offset gravure printing, lithographic printing such as offset printing, screen printing The binder layer is laminated by coating or printing such as stencil printing. In particular, a coating using a roll coater is preferable because a uniform layer thickness can be obtained. The thickness of the binder layer is preferably about 0.5 to 2 times the average particle diameter of the filler to be embedded.
[0023]
Next, a filler is attached to the binding layer on the substrate. Examples of the method include a method in which a filler filled in a container is fluidized by vibration or fluidized air, and a substrate is passed through the filler, or a filler is sprayed on a binder layer by spraying. The purpose of adhering the filler to the binder layer is to prevent the pressurizing medium from adhering to the binder layer in the step of embedding the filler in the binder layer by the subsequent pressurizing medium. May be attached to the entire surface of the binder layer in a high density state by the adhesive force of the binder layer.
[0024]
“Step 2: Embedding of filler in the binder layer”
The filler adhered to the surface of the binding layer is embedded in the binding layer through a pressure medium. As the method, the pressurized medium is put into a suitable container, the pressurized medium is vibrated together with the container, and the substrate with the filler attached to the binder layer is put in or passed through. Apply external force to the filler. Then, the filler is struck by a pressurized medium and embedded in the surface layer of the binding layer. By such a method, the filler is bonded to the binder layer with a uniform embedding depth.Part fromIt protrudes and is embedded at a high density throughout, and is formed as a single filler layer without being laminated in the binder layer. As an external force applied for embedding the filler, rotation, dropping, or the like may be employed in addition to vibration. In the case of rotation, a rotating container or a container having a stirring blade inside is used. In addition, when adopting a drop as an external force, a V blender, a tumbler or the like is used.
[0025]
Here, the pressurization medium used for embedding a filler is illustrated.
The pressurizing medium is a granular material that acts to hit the filler by vibration or the like and embed it in the binder layer as described above. Iron, carbon steel, alloy steel, copper and copper alloy, aluminum and aluminum alloy, other Made of various metals and alloys, or Al₂O₃, SiO₂TiO₂, ZrO₂  Those made of ceramics such as SiC, and those made of glass, hard plastics and the like are used. Further, hard rubber may be used as long as a sufficient striking force can be applied to the powder. In any case, the material of the pressure medium is appropriately selected according to the material of the filler. The shape is preferably close to a true sphere so that the pressure applied to the filler is uniform, and the overall particle distribution is preferably as narrow as possible. The particle diameter of the pressurizing medium is appropriately selected according to the filler material and the filler embedding depth, but is preferably about 0.3 to 2.0 mm.
[0026]
The filler embedding depth is such that the peeling of the filler from the binder layer is suppressed, and the lens effect can be reliably expressed by protruding from the surface of the binder layer. 90%, preferably 30 to 90%, more preferably 40 to 70% is desirably embedded, and can be adjusted according to the optical characteristics of the lens.
[0027]
"Step 3: Curing the binder layer"
The adhesive layer is cured by irradiating the binder layer embedded with the filler with radiation such as ultraviolet rays and electron beams. Up to the filler embedding process, it is preferable that the adhesive is soft and the embedding depth of the filler is easy to control, but after embedding the filler, in order to maintain the optical characteristics of the filler lens, It is necessary to cure by radiation so as not to cause heat flow.
[0028]
“Process 4: Removal of excess filler”
After the binder layer curing step, excess filler is removed. The surplus filler is, for example, a filler that is imperfectly embedded in the binder layer, or only adhered to the embedded filler by interparticle forces such as van der Waals force. Is removed by applying fluid pressure to the filler layer by water washing or air blow. When the particle diameter of the filler is relatively small, it is preferable to perform wet cleaning using ion exchange water or the like.
[0029]
【Example】
Next, an embodiment that further embodies the present invention will be described. In the following, “part” means “part by weight”.
<Example 1>
As the transparent substrate, triacetyl cellulose (trade name: Fuji Tac UVD80, manufactured by Fuji Photo Film Co., Ltd., refractive index 1.49) having a thickness of 80 μm was used. On one side of this film, the following binder layer coating solution stirred and mixed with a disper for 15 minutes was coated with a reverse coater so that the thickness after drying was 10 μm, and dried at 100 ° C. for 2 minutes. A binding layer was formed.
[0030]
[Composition of binder layer coating solution]
・ 100 parts acrylic adhesive
(Product name: SK Dyne 1852, total solid content 23% ethyl acetate solution, manufactured by Soken Chemical Co., Ltd.)
・ Isocyanate curing agent 1.5 parts
(Product name: D-90, 90% total solid ethyl acetate solution, manufactured by Soken Chemical Co., Ltd.)
・ Epoxy compound 45 parts
(Product name: Cyracure UVR-6110, manufactured by Union Carbide Corp.)
・ Acrylic compound 45 parts
Tripentaerythritol polyacrylate
・ Photo cationic polymerization initiator 2 parts
(Product name: Cyracure UVI-6990, manufactured by Union Carbide Corp.)
・ Isopropyl alcohol 5 parts
・ Methyl ethyl ketone 210 parts
・ 650 parts of ethyl acetate
[0031]
Next, as a filler, a filler made of methyl silicone having a monodisperse particle diameter of 4.5 μm and a refractive index of 1.45 was used, and this filler was put into a perforated plate container that ejects air from the bottom. Thereafter, the container is vibrated, and the filler is fluidized by the synergistic effect of the vibration and the blown air. The above-mentioned film having the binding layer formed on the surface was appropriately passed over time, and a filler was attached to the surface of the binding layer.
[0032]
Subsequently, the filler was embedded in the surface layer of the binder layer by the vibration apparatus shown in FIG. In this vibration apparatus, a pressurized medium, a filler, and the film are placed in a container C set on the vibration mechanism V, and the charged material is vibrated together with the container C by the vibration mechanism V. A filler is embedded in the binding layer of the film.
[0033]
The container C is made of a hard material such as hard synthetic resin or metal, and is formed in a bowl shape having an opening c1 at the top, and bulges upward at the center of the bottom c2 to open the opening c1. A columnar portion c3 that reaches the same height as the projection is provided. On the other hand, in the vibration mechanism V, a diaphragm f3 is mounted on a machine base F via coil springs f1 and f2, and a vertical shaft f4 extending upward is projected from the center of the upper surface of the diaphragm f3, so that the diaphragm f3 is provided. The motor f5 is fixed to the center of the lower surface of the motor, and 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 part 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 is like that.
[0034]
3 kg of spherical zirconia spheres having a particle diameter of 0.5 mm as a pressurizing medium are put into the container C of this vibration apparatus, andMade of methyl silicone30 g of filler was added and both were mixed. Next, the vibrating device is held in a state where the container C is inclined 45 degrees from the state shown in FIG. 2 and the container C is vibrated, so that the film faces the binding layer to which the filler is attached upward. Then, the bottom of the container C was moved at a speed of 30 cm / min to pass through the pressurized medium. As a result, the filler is struck by the vibrating pressurized medium and embedded in the surface layer of the binding layer to form a filler layer.
[0035]
Next, using one condensing high-pressure mercury lamp with a UV lamp output of 120 w / cm, the irradiation distance (distance from the lamp center to the coating surface) is 10 cm, the processing speed (speed relative to the UV lamp on the coating substrate side) is 5 m / In minutes, the film was irradiated with UV to cure the coating film. Next, the filler layer was washed by applying a water pressure shower to the filler layer using ion-exchanged water to remove excess filler, and then the whole was dried by air blowing. Further, aging was performed at 20 to 40 ° C. for 10 days to obtain a filler lens of Example 1.
[0036]
<Example 2>
A filler lens of Example 2 was obtained in the same manner as in Example 1 except that dipentaerythritol triacrylate was used as the acrylic compound in the coating liquid for the binder layer.
[0037]
<Comparative Example 1>
A paint obtained by dispersing a mixture of the following components in a sand mill for 30 minutes was converted to triacetyl cellulose (trade name: Fujitac UVD80, manufactured by Fuji Photo Film Co., Ltd.) with a film thickness of 80 μm and a transmittance of 92%. , With a refractive index of 1.49), applied by a reverse coating method, dried at 100 ° C. for 2 minutes, and then irradiated with ultraviolet light with one 120 w / cm condensing high-pressure mercury lamp (irradiation distance 10 cm, irradiation time) 30 seconds), the coating film was cured to obtain a filler lens of Comparative Example 1.
・ 95 parts of epoxy acrylate UV resin
(Product name: KR-566, 95% solid content solution, manufactured by Asahi Denka Co., Ltd.)
・ 10 parts of crosslinked acrylic bead pigment
(Product name: MX150, particle size 1.5 μm ± 0.5, manufactured by Soken Chemical Co., Ltd.)
・ Isopropyl alcohol 230 parts
[0038]
<Comparative example 2>
A filler lens of Comparative Example 2 was obtained in the same manner as in Example 1 except that the composition of the binder layer coating liquid of Example 1 was changed to the following and the ultraviolet irradiation step was omitted.
[Composition of binder layer coating solution]
・ 100 parts acrylic adhesive
(Product name: SK Dyne 811L, total solid content 23% ethyl acetate solution, manufactured by Soken Chemical Co., Ltd.)
・ Isocyanate curing agent 1.5 parts
(Product name: D-90, 90% total solid ethyl acetate solution, manufactured by Soken Chemical Co., Ltd.)
[0039]
1. Observation of filler layer
The plane and cross section of the filler lenses of Examples 1 and 2 were observed with an electron microscope. 3 (a), (b), and (c) are micrographs taken at 1000, 2000, and 5000 times, respectively, of the plane of the filler lens of Example 1, and FIGS. 4 (a) and 4 (b). These are the microscope pictures which each image | photographed the cross section of the filler lens of Example 1 with the magnification of 2000 times and 5000 times. 5 (a), (b), and (c) are micrographs taken at 1000, 2000, and 5000 times, respectively, of the plane of the filler lens of Example 2, and FIGS. b) are micrographs obtained by photographing the cross section of the filler lens of Example 2 at a magnification of 2000 times and 5000 times, respectively. In both Examples 1 and 2, as can be seen from the planar photographs, the filler is almost uniformly dispersed in the binder layer in a dense state. As can be seen from the cross-sectional photograph, in the case of Example 1, about 70% of the diameter is embedded in the binding layer, and in Example 2, the filler is embedded in the state where about 60% of the diameter is embedded. It protrudes uniformly from the surface.
[0040]
2. Light diffusivity test
With respect to the filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2, when the light is incident from the film 1 side as shown in FIG. 7A and when the light enters the filler 3 as shown in FIG. The total light diffuse transmittance: T% and the total light diffuse reflectance: R% when incident from the side were measured with a spectrophotometer UV3100 manufactured by Shimadzu Corporation using an integrating sphere method.
The measurement method is as follows. With respect to the total light diffusion transmittance: T%, as shown in FIG. 8A, a filler lens L is interposed between the incident light and the reference white plate (magnesium sulfate) 10 in the forward direction. The total light diffuse transmittance of the scattered light was measured. In FIG. 8 (a), light is incident from the film side as shown in FIG. 7 (a), but the same process was performed when light was incident from the filler side as shown in FIG. 7 (b).
Further, the total light diffuse reflectance: R% is determined by measuring the total light diffuse reflection value of light scattered on the reference white plate (magnesium sulfate) and scattered backward, and set the value to 100. Next, as shown in FIG. 8B, light was incident on the filler lens L, the total light diffuse reflection value was measured, and the ratio was calculated with respect to the total light diffuse reflection value of the reference white plate. In FIG. 8B, light is incident from the film side as shown in FIG. 7A, but the same process was performed when light was incident from the filler side as shown in FIG. 7B. The measurement wavelength in this case was 400 to 700 nm, and the measurement value was shown as an average value in this wavelength region.
[0041]
Next, the filler lenses of Examples 1 and 2 and Comparative Examples 1 and 2 were left under high temperature and high humidity (80 ° C., 90%) conditions for 3 days, and then a light diffusivity test was performed in the same manner as above. High temperature and high humidity resistance, that is, reliability under high temperature and high humidity was evaluated.
[0042]
3. Adhesive strength evaluation
Adhesive strength was measured based on JIS Z0237 using the coating liquid for binding layers in each Example and Comparative Example, which was applied and dried on a PET film (dry coating thickness: 10 μm). The evaluation was performed before and after curing (curing conditions are the same as in Example 1).
These results are shown in Table 1.
[0043]
[Table 1]

[0044]
According to Table 1, in Comparative Example 1 in which the filler was dispersed in the resin, the total light diffusion transmittance was about 91% regardless of whether the light was incident from the film side or the filler side. There was no difference of about 26%. On the other hand, in the light scattering properties of Examples 1 and 2 and Comparative Example 2, a difference was observed between the light incident direction from the film side and the filler side. When light is incident from the film side, the total light diffuse transmittance is lower than that of Comparative Example 1, but the total light diffuse reflectance is high, and when light is incident from the filler side, the total light diffuse transmittance is high. However, the total light diffuse reflectance was low.
[0045]
Further, after leaving under high temperature and high humidity, the light scattering properties of Examples 1 and 2 and Comparative Example 1 were hardly changed, but Comparative Example 2 in which the adhesive of the binder layer was not cured. The total light diffuse transmittance increased when light was incident from the film side, while the total light diffuse reflectance decreased. In other words, according to the production method of the present invention, a filler effect in which light scattering properties are different depending on whether the incident direction of light is front or back, and keeps specific light scattering properties even under high temperature and high humidity. It is possible to obtain a lens.
[0046]
For example, when used in a transmissive liquid crystal display, the film 1 of the filler lens L of the present invention is used as a light diffusion plate between the liquid crystal panel 20 and the backlight 21 as shown in FIG. If it is arranged toward the 20 side, the light transmittance of the backlight 21 is extremely high, and in addition to this, sunlight and lamp light incident from the front side of the display (upper side in the figure) are easily reflected. Therefore, the amount of light that illuminates the liquid crystal panel 20 becomes extremely large, and a clear liquid crystal image and a power saving effect can be obtained. Also, as shown in FIG. 9B, when the film 1 is disposed on the front side of the liquid crystal panel 20 so as to face forward, the transmittance of the backlight 21 is high, so that it is used as a light diffusion lens having a very wide viewing angle. can do.
[0047]
【The invention's effect】
As described above, according to the present invention, since the filler is embedded in the binding layer surface layer in a state in which a part protrudes from the surface of the binding layer, the lens effect of the filler is sufficiently expressed, and further, the binding Since the adhesive of the layer is cured, it is possible to provide a method for producing a filler lens that keeps this optical property even under high temperature and high humidity conditions.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an example of a filler lens of the present invention.
FIG. 2 is a front sectional view of a vibration exciter suitable for producing the filler lens of the present invention.
3 is a photomicrograph showing the plane of the filler lens of Example 1 of the present invention at (a) 1000 times, (b) 2000 times, and (c) 5000 times. FIG.
4 is a photomicrograph showing the cross section of the filler lens of Example 1 of the present invention at (a) 2000 times and (b) 5000 times. FIG.
5 is a photomicrograph showing the plane of the filler lens of Example 2 of the present invention at (a) 1000 times, (b) 2000 times, and (c) 5000 times. FIG.
6 is a photomicrograph showing the cross section of the filler lens of Example 2 of the present invention at (a) 2000 times and (b) 5000 times. FIG.
FIG. 7 is a diagram for explaining light scattering properties with respect to a filler lens, and is a schematic diagram showing total light diffuse transmittance and total light diffuse reflectance.
FIGS. 8A and 8B are diagrams for explaining a method for measuring light scattering properties, and are schematic diagrams showing a method for measuring (a) total light diffuse transmittance and (b) total light diffuse reflectance. FIGS.
9A and 9B are cross-sectional views schematically showing an example in which the filler lens of the present invention is applied to a liquid crystal display.
FIG. 10 is a cross-sectional view schematically showing an example of a conventional filler lens.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Film (base | substrate), 2 ... Binder layer, 3 ... Filler, 3A ... Filler layer, L ... Filler lens.

Claims (3)

A base, a binding layer containing at least a radiation-curable resin laminated directly or via another layer on the base, and a part of the surface of the binding layer protrude from the surface of the binding layer A method for producing a filler lens comprising a filler layer embedded in a state, the step of laminating the binder layer on the substrate directly or via another layer, and the pressure being a granular material Stroke the filler with an external force through a medium to embed the filler in the binder layer, cure the binder layer, and remove excess filler attached to the laminate obtained in the step And a process for producing a filler lens. The method for manufacturing a filler lens according to claim 1 , wherein the filler is embedded in a single layer with a high density in a plane direction. The filler is in the binder layer, the production method of the filler lens according to claim 1 or 2, characterized in that the embedded 10% to 90% of its diameter.

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