JP6255676B2 - Method for manufacturing light diffusion sheet and method for manufacturing light diffuser - Google Patents

Description

The present invention relates to a method for producing a light diffusion sheet or light diffuser. More specifically, the present invention relates to a method for manufacturing a light diffusion sheet or light diffuser having anisotropic light diffusion characteristics.

It is known that a concavo-convex pattern composed of fine wavy concavo-convex is formed on the surface, and the concavo-convex pattern forming sheet having an average pitch of 1 to 10 μm can be used as a light diffuser (Patent Documents 1 and 2).

As a method for producing such a concavo-convex pattern forming sheet, a tension is applied in at least one direction of the laminated sheet in the state of a laminated sheet in which at least one hard layer is laminated on one side or both sides of the heat-shrinkable film. Then, a method for producing a concavo-convex pattern forming sheet (Patent Document 3) is known in which at least a hard layer of the laminated sheet is meandered and deformed by heating and shrinking.

However, a method for producing an uneven pattern forming sheet that is a light diffuser that efficiently diffuses a point light source and uniformly illuminates the longitudinal direction of display lighting, hallway lighting, passage lighting, etc. has not been known. .
JP-A-10-123307 Japanese Patent Application Laid-Open No. 2006-261064 JP 2008-304651 A

The present invention is an anisotropic light diffusion characteristic suitable for an illumination device that uses a light from a point light source or a light source unit in which point light sources are arranged and illuminates a space extending in one direction such as a passage efficiently and uniformly in the longitudinal direction. A method for producing a light diffusing sheet having the following is provided.

As a result of intensive studies on a method for producing a light diffusing sheet having excellent anisotropic light diffusing characteristics, the present inventors have completed the following production method.

[1] At least one hard layer is laminated on one side of a heat-shrinkable film, and a laminating step for producing a laminated sheet, and at least the hard layer of the laminated sheet is meandered and deformed by heating and deforming the laminated sheet. An uneven pattern forming step of forming unevenness on the surface of the hard layer, and a method of manufacturing a light diffusion sheet,
When one direction along the surface of the laminated sheet is the X direction, the direction along the surface of the laminated sheet and perpendicular to the X direction is the Y direction,
In the concavo-convex pattern forming step, tension is applied at least in the Y direction, and a 1/10 value diffusion angle of light incident on the light diffusion sheet from the surface on which the hard layer is laminated is 70 to 80 degrees in the X direction, Y direction. The manufacturing method of the light-diffusion sheet characterized by shrinking so that it may become 5-15 degree | times.
[2] A laminating step in which at least one hard layer is laminated on one side of the heat-shrinkable film to produce a laminated sheet, and at least the hard layer of the laminated sheet is meandered and deformed by heating and deforming the laminated sheet. A master mold forming step for obtaining a master by forming a concavo-convex pattern on the surface of the hard layer, and a transfer mold having a concavo-convex pattern on one side by transferring the shape of the concavo-convex pattern formed on the surface of the hard layer to a resin composition And a transfer step for obtaining a light diffusing body, wherein the transfer mold is obtained as a light diffusing body,
When one direction along the surface of the laminated sheet is the X direction, the direction along the surface of the laminated sheet and perpendicular to the X direction is the Y direction,
In the concavo-convex pattern forming step, tension is applied at least in the Y direction, and a 1/10 value diffusion angle of light incident on the light diffuser from the surface on which the hard layer is laminated is 70 to 80 degrees in the X direction, and the Y direction. A method for producing a light diffuser, wherein the light diffuser is contracted to 5 to 15 degrees.
[3] At least one hard layer is laminated on one side of the heat-shrinkable film to produce a laminated sheet, and by heating and deforming the laminated sheet, at least the hard layer of the laminated sheet is meandered and deformed. A primary master mold forming step of forming a concave / convex pattern on the surface of the hard layer to obtain a primary master block, and the concave / convex pattern formed on the surface of the hard layer are applied to the resin composition or metal composition 1 to n times. A 2- (n + 1) -order matrix forming step for transferring a shape to obtain a 2- (n + 1) -order matrix having a concavo-convex pattern on one side, and a concavo-convex pattern of the 2- (n + 1) -order matrix for further different resin composition A method of manufacturing a light diffuser having a replica manufacturing step of obtaining a replica having a concavo-convex pattern on one side by transferring a shape to an object, and obtaining the replica as a light diffuser,
When one direction along the surface of the laminated sheet is the X direction, the direction along the surface of the laminated sheet and perpendicular to the X direction is the Y direction,
In the concavo-convex pattern forming step, tension is applied at least in the Y direction, and a 1/10 value diffusion angle of light incident on the light diffuser from the surface on which the hard layer is laminated is 70 to 80 degrees in the X direction, and the Y direction. A method for producing a light diffuser, wherein the light diffuser is contracted to 5 to 15 degrees.
[4] The method for producing a light diffusing sheet or a light diffusing body according to any one of claims 1 to 3, wherein an average pitch of the concavo-convex pattern when measured along the Y direction of the light diffusing sheet is adjusted to 1 to 20 μm.

In the method for producing a light diffusing sheet or light diffusing body of the present invention, a light diffusing sheet that can easily form a fine concavo-convex pattern on a surface with a large area and has excellent anisotropic light diffusing characteristics can be easily and in large quantities. Can be manufactured.

(Production method of light diffusion sheet)
An embodiment of the method for producing a light diffusion sheet of the present invention will be described.
As shown in FIG. 1, the light diffusing sheet manufacturing method of the present embodiment has a hard layer 12 a (hereinafter referred to as a surface smooth hard layer 12 a) having a smooth surface on the entire surface of one surface of the uniaxial heat-shrinkable film 11. ) And forming the laminated sheet 10a, and the step of causing the largest contraction by heating of the laminated sheet 10a as the X direction and applying a tension in the direction orthogonal to the X direction (Y direction) to cause heat deformation It consists of.
By adopting the above-described method, the hard layer of the laminated sheet is meandered and a concavo-convex pattern 13 as shown in FIG. 2 is formed on the entire surface of one side of the uniaxial heat-shrinkable film 11. Is obtained.
Here, the surface smooth hard layer 12a is a layer having a center line average roughness of 0.1 μm or less described in JIS B0601.
“Meandering deformation” refers to a deformation that forms a wavy uneven pattern as shown in FIG.

A conventionally known film can be used as the uniaxial heat-shrinkable film 11 of the present invention. A film, a uniaxial shrinkable polyvinyl chloride shrink film, or the like can be used. These uniaxial heat-shrinkable films have the property of shrinking mainly in one direction when heated at a shrinkage temperature or higher. The thickness of the uniaxial heat-shrinkable film 11 is generally 10 to 500 μm. Preferably, it is 20-100 micrometers from the point of the availability of a film.

The surface smooth hard layer 12a of the present invention is composed of at least one selected from a metal, a metal compound, or a resin having a glass transition temperature 3 ° C. higher than the heat shrinkage temperature of the uniaxial heat shrinkable film 11. . With such a configuration, when the laminated sheet 10a is heated and shrunk, the elastic modulus of the surface smooth hard layer 12a can be made larger than that of the uniaxial heat-shrinkable film 11, and the surface smooth hard layer 12a bends in a wavy shape and meanders. Thus, the uneven pattern 13 can be easily formed.

As the metal that can be used for the surface smooth hard layer 12a, the elastic modulus is not excessively high and the uneven pattern 13 can be formed more easily. Therefore, gold, aluminum, silver, carbon, copper, germanium, indium, magnesium Niobium, palladium, lead, platinum, silicon, tin, titanium, vanadium, zinc, and at least one metal selected from the group consisting of bismuth is preferable. The metal here includes a semi-metal.

In addition, as a metal compound, for the same reason as described above, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, tin oxide, copper oxide, indium oxide, cadmium oxide, lead oxide, silicon oxide, barium fluoride, fluoride It is preferably at least one metal compound selected from the group consisting of calcium, magnesium fluoride, zinc sulfide, and gallium arsenide. Among these, titanium oxide is preferable because it is a photocatalyst that decomposes organic substances attached to the surface when exposed to light and has a self-cleaning function.

Further, the resin may be a resin having a glass transition temperature that is 3 ° C. or more higher than the heat shrinkage temperature of the uniaxial heat shrinkable film 11. For example, polyvinyl alcohol, polystyrene, acrylic resin, styrene-acrylic copolymer Styrene-acrylonitrile copolymer, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, fluororesin and the like, and two or more kinds of resins may be mixed.

When the surface smooth hard layer 12a is a metal or a metal compound, the thickness is preferably 1 nm to 2 μm. Moreover, when the surface smooth hard layer 12a is resin, it is preferable that thickness is 5 nm-10 micrometers. It is preferable that the thickness of the surface smooth hard layer 12a is controlled within the above range, and the average pitch of the uneven pattern 13 is 1 to 20 μm.
Here, the average pitch A is an average value of the pitches A1, A2, A3,.
Each pitch A1, A2, A3... May be continuously changed after satisfying that the average pitch A is 1 to 20 μm.
In addition, a primer layer may be formed between the uniaxial heat-shrinkable film 11 and the surface smooth hard layer 12a for the purpose of improving adhesion.

As a method of forming the surface smooth hard layer 12a on the uniaxial heat-shrinkable film 11, in the case of (A) a metal or a metal compound, for example, (1) on one side of the uniaxial heat-shrinkable film 11 And a method of depositing a metal or a metal compound, and (2) a method of laminating a surface smooth hard layer 12a prepared in advance on one surface of the uniaxial heat-shrinkable film 11. In the case of (B) resin, for example, (3) a method of applying a resin solution or dispersion with a spin coater or bar coater and drying the solvent, and (4) a uniaxial heat-shrinkable film. 11 is a method of laminating a previously prepared surface smooth hard layer 12a on one surface.

For example, the following method can be applied as a method of applying heat in the direction of heat shrinkage of the laminated sheet 10a of the present invention to cause heat deformation.

An embodiment will be specifically described with reference to FIG.
While applying tension in the flow direction (Y direction) of the continuous sheet-shaped laminated sheet (before heating deformation) 10a that mainly heat-shrinks in the width direction, it is introduced into the heating zone 40, and the width of the laminated sheet 10a is increased in the heating zone 40. The light diffusion sheet 10 is manufactured by continuously reducing the light diffusion sheet 10.

By continuously heating and deforming the laminated sheet 10a in the width direction while applying tension in the Y direction, a 1/10 value diffusion angle of light incident on the light diffusion sheet from the surface on which the hard layer is laminated is obtained. A light diffusion sheet having an X direction of 70 to 80 degrees and a Y direction of 5 to 15 degrees can be manufactured more stably.

In the method described above, the laminated sheet may be heated and deformed while applying tension in the X direction of the laminated sheet. As shown in FIG. 3, as a method of heating and deforming the laminated sheet while applying tension in the X direction of the laminated sheet, gripping both ends in the X direction of the laminated sheet with grips and controlling the tension in the X direction, the heating zone There is a method of performing heat deformation so that the width of the laminated sheet in the X direction continuously decreases from the inlet to the outlet.

The hard layer is laminated by continuously deforming the laminated sheet 10a in the width direction while applying tension in the Y direction of the laminated sheet 10a and controlling the tension applied in the X direction of the laminated sheet 10a. It is possible to more stably manufacture a light diffusion sheet in which the 1/10 value diffusion angle of light incident on the light diffusion sheet from the surface is 70 to 80 degrees in the X direction and 5 to 15 degrees in the Y direction.

In the method for producing a light diffusing sheet of the present invention, the deformation rate in the Y direction of the laminated sheet 10a is preferably controlled within 10%, more preferably within 5%. By setting the deformation rate in the Y direction of the laminated sheet 10a within 10%, the 1/10 value diffusion angle of light incident on the light diffusion sheet from the surface on which the hard layer is laminated is 70 to 80 degrees in the X direction, Y A light diffusion sheet having a direction of 5 to 15 degrees can be manufactured more stably.
Here, the deformation rate in the Y direction of the laminated sheet 10a is determined by marking two linear points along the Y direction of the laminated sheet 10a and measuring the distance between the two points before and after heat deformation. (Distance between two points) − (distance between two points after heat deformation) / (distance between two points before heat deformation) × 100 (%).

In the method for producing a light diffusing sheet of the present invention, the average depth B of the bottom 13b of the concavo-convex pattern 13 is easily set to 30% or more, more preferably 70% or more when the average pitch A is 100%. Is preferable for improving the light diffusion performance.

Here, the bottom portion 13b is a local minimum point of the concave portion of the concavo-convex pattern 13, and the average depth B is obtained when viewing a cross section (see FIG. 5) obtained by cutting the light diffusion sheet 10 along the length direction. The average value (Bav) of the lengths B1, B2, B3... From the reference line L1 parallel to the surface direction of the entire light diffusing sheet 10 to the top of each convex portion, and from the reference line L1 to the bottom of each concave portion. It is the difference (bAV−BAV) from the average value (bAV) of the lengths b1, b2, b3. The top part of the convex part and the bottom part of the concave part are in contact with the surface of the hard layer 12 opposite to the heat-shrinkable film 11 side. Each depth B1, B2, B3... May change continuously after satisfying that the average depth B is 10% or more when the average pitch A is 100%. Absent.

Furthermore, for the purpose of improving the uniformity in the width direction of the concavo-convex pattern of the light diffusion sheet 10 manufactured by heat deformation, or for the purpose of thermal stabilization, as shown in FIG. It is also possible to perform a widening process with a shrinkage rate of 20% or less. In this case, the widening process is performed by gripping the laminated sheet 10 after heat deformation with the grip grip 31 that becomes wider toward the downstream in the flow direction.
Here, 20% or less of the shrinkage rate means that, for example, when the width of the laminated sheet 10 after heat deformation is 40% of the width of the laminated sheet 10a before heat deformation, the shrinkage rate is 60% and the widening process is performed. 20% or less, that is, 12% or less of the original length.

In the production method of the present invention, in addition to the control of the tension in the Y direction and the control of the tension in the X direction, by controlling the elastic modulus and thickness of the surface smooth hard layer 12a of the laminated sheet 10a of the present invention, The average pitch A of the uneven pattern 13 can be controlled.
Moreover, the average depth B of the concavo-convex pattern 13 can be controlled by controlling the heating deformation rate of the uniaxial heat-shrinkable film 11.
Specifically, the average pitch A increases as the elastic modulus of the surface smooth hard layer 12a increases or the thickness increases. Further, the average depth B increases as the heat shrinkage rate increases.
Desired quality can be obtained by appropriately selecting the above conditions.

When the uniaxial heat-shrinkable film 11 is used for the laminated sheet 10a, the wavy uneven pattern 13 is formed along the direction orthogonal to the shrinking direction. Even if a biaxial heat-shrinkable film having a different shrinkage rate in the axial direction is used in place of the uniaxial heat-shrinkable film 11, a light diffusion sheet having anisotropy in light diffusibility can be obtained.

In the above-described embodiment, the surface smooth hard layer is provided on the entire surface of one side of the heat-shrinkable film. However, the surface smooth hard layer may be provided on a part of one surface of the heat-shrinkable film, or the heat-shrinkable property. A smooth surface hard layer may be provided on the entire surface of both surfaces of the film, or a smooth surface hard layer may be provided on a part of both surfaces of the heat-shrinkable film.

According to the present invention, the light diffusion sheet 10 can be manufactured easily and in a large area.
Moreover, according to this manufacturing method, the light diffusion sheet 10 having excellent anisotropic light diffusion characteristics can be easily manufactured by controlling the average pitch A and the average depth B of the uneven pattern 13.

In the method for producing a light diffusion sheet of the present invention, the 1/10 value diffusion angle of light incident on the light diffusion sheet from the surface on which the hard layer is laminated is 5 to 15 degrees in the X direction and 70 to 80 degrees in the Y direction. It is made to shrink so that it may become.

When the light diffusion sheet is used as a diffuser of a lighting device in a passage or hallway, if the 1/10 value diffusion angle in the X direction is less than 5 degrees, an insufficient illuminance portion is generated in the width direction, exceeding 15 degrees. Because the wall surface becomes too bright and the illuminance at the foot is relatively low, it becomes difficult to see the foot.
Further, if the 1/10 value diffusion angle in the Y direction is less than 70 degrees, unevenness occurs in the brightness in the longitudinal direction of the passages and hallways, and if it exceeds 80 degrees, light reaches an area that does not require illumination. Irradiation reduces the illuminance in areas that require illumination.

When the light diffusing sheet is used as a diffuser of a lighting device for illuminating an exhibit displayed on a wall surface, if the 1/10 value diffusion angle in the X direction is less than 5 degrees, the exhibit has insufficient illuminance When the angle exceeds 15 degrees, it becomes easy for the illumination light to enter directly into the eyes of the observer of the exhibit, making it difficult to observe the exhibit. Since the wall surface becomes too bright and the illuminance at the foot is relatively low, it becomes difficult to see the foot.
Further, if the 1/10 value diffusion angle in the Y direction is less than 70 degrees, an uneven portion of the brightness of the exhibit occurs, and if it exceeds 80 degrees, the observer observes the exhibit from an oblique direction. This makes it easier for the eyes to get direct lighting, making it difficult to see the exhibits.

In order to solve the shortage of the 1 / 10-value diffusion angle, it is necessary to arrange the point light sources on a straight line with a small interval, which increases the manufacturing cost and power consumption of the lighting device, resulting in poor efficiency.

As the method for adjusting the 1/10 value diffusion angle, the shrinkage rate in the respective axial directions, the ratio of the vertical and horizontal shrinkage rates or the difference in the vertical and horizontal shrinkage rates, the adjustment of the tension applied in the X-axis direction in the shrinking process, and Y One of tension adjustment applied in the axial direction, adjustment of tension ratio or difference in the X-axis direction and Y-axis direction, adjustment of heating conditions (temperature, time, combination with tension conditions, cooling conditions, etc.), or The method of combining two or more is mentioned.

The manufacturing method according to the present invention with the 1/10 value diffusion angle as the above condition, when illuminating a passage, corridor, platform, etc., even with a small number of point light sources, it is efficient in the longitudinal direction and uniform illuminance. It becomes the light-diffusion sheet used for the illuminating device which can be illuminated with.

In the illumination device, the light diffusion sheet or light diffuser of the present invention is disposed on the light exit surface side of the light emitting diode. In the installation of the lighting device, the longitudinal direction of the passage, hallway, platform, etc., and the direction in which the 1/10 value diffusion angle of the light incident on the light diffusion sheet from the surface on which the unevenness is formed are maximized. Install the lighting device to be the same. Moreover, one light source may be arranged for one light diffusion sheet of the present invention, or a plurality of light source units may be arranged.

The light diffusion sheet or light diffuser of the present invention may be disposed between the light source unit and the illumination unit, may be affixed to the surface of the illumination cover, and may also serve as the illumination cover.

In the light diffusing sheet and light diffusing body of the present invention, the heat-shrinkable film has a light diffusing property composed of an inorganic compound within a range that does not significantly impair the optical properties such as light transmittance for the purpose of further enhancing the light diffusing effect. Agent, an organic light diffusing agent made of an organic compound, or fine bubbles can be contained.

This invention includes the manufacturing method of the light diffusing body which transfers the shape of the surface where the said hard layer of the light diffusing sheet manufactured by the above-mentioned manufacturing method was laminated | stacked, and obtains the light diffusing body which has an uneven | corrugated pattern on the surface.

Specific examples of the method for producing the light diffuser include the following methods (a) to (c).
(A) An uncured ionizing radiation curable resin is applied to the surface of the light diffusion sheet on which the hard layer is laminated, and the cured resin film is cured by irradiating with ionizing radiation. Is peeled from the light diffusion sheet. Here, the ionizing radiation is usually ultraviolet rays or electron beams, but in the present invention, visible rays, X-rays, ion rays and the like are also included.
(B) An uncured liquid thermosetting resin is applied to the surface of the light diffusion sheet on which the hard layer is laminated, heated to cure the liquid thermosetting resin, and then the cured coating film is applied. A method of peeling from the light diffusion sheet.
(C) A sheet-like thermoplastic resin is brought into contact with the surface of the light diffusion sheet on which the hard layer is laminated, and the thermoplastic resin is heated and softened while pressing the thermoplastic resin against the light diffusion sheet, and then cooled. The method of peeling the cooled sheet-like thermoplastic resin from the light diffusion sheet.

Moreover, a process sheet | seat is produced using a light-diffusion sheet, An optical element can also be manufactured using the process sheet | seat. Specific methods using the process sheet include the following methods (d) to (f).
(D) Metal plating such as nickel is performed on the surface of the light diffusion sheet on which the hard layer is laminated, and a plating layer (uneven pattern transfer material) is laminated, and the plating layer is peeled off from the light diffusion sheet. Then, a metallic process sheet is prepared, and then an uncured ionizing radiation curable resin is applied to the surface of the process sheet that is in contact with the surface on which the hard layer is laminated, and the ionizing radiation is irradiated. A method of peeling the cured coating film from the process sheet after curing the curable resin.
(E) A process sheet is prepared in the same manner as (d), and an uncured liquid thermosetting resin is applied to the surface of the process sheet that is in contact with the surface on which the hard layer is laminated, A method of peeling the cured coating film from the process sheet after curing the resin by heating.
(F) A process sheet is prepared in the same manner as in (d), and a sheet-like thermoplastic resin is brought into contact with the surface of the process sheet that has been in contact with the surface on which the hard layer is laminated. A method in which a resin is heated and softened while being pressed against a process sheet, then cooled, and the cooled sheet-like thermoplastic resin is peeled from the process sheet.

A specific example of the method (a) will be described. As shown in FIG. 6, first, an uncured liquid ionizing radiation curable resin 113 c is applied by a coater 120 to the surface of the web-shaped light diffusion sheet on which the uneven pattern 113 a is formed. Next, the process sheet 110 coated with the curable resin is pressed by passing through a roll 130, and the curable resin is filled into the concave-convex pattern 113a of the light diffusion sheet. Thereafter, ionizing radiation is irradiated by the ionizing radiation irradiation device 140 to crosslink and cure the curable resin. And the web-like optical element 150 can be manufactured by peeling the ionizing radiation curable resin after hardening from the said light-diffusion sheet.

In the method (a), for the purpose of imparting releasability to the surface of the light diffusion sheet on which the hard layer is laminated, a silicone resin or fluororesin is applied before application of an uncured ionizing radiation curable resin. And the like, and a thickness of about 1 to 10 nm may be provided.
Examples of the coater that coats an uncured ionizing radiation curable resin on the surface of the light diffusion sheet on which the uneven pattern is formed include a T-die coater, a roll coater, and a bar coater.
Uncured ionizing radiation curable resins include epoxy acrylate, epoxidized oil acrylate, urethane acrylate, unsaturated polyester, polyester acrylate, polyether acrylate, vinyl / acrylate, polyene / acrylate, silicon acrylate, polybutadiene, and polystyrylmethyl methacrylate. 1 type selected from monomers such as prepolymers such as aliphatic acrylate, alicyclic acrylate, aromatic acrylate, hydroxyl group-containing acrylate, allyl group-containing acrylate, glycidyl group-containing acrylate, carboxy group-containing acrylate, halogen-containing acrylate, etc. The thing containing the above component is mentioned. The uncured ionizing radiation curable resin is preferably diluted with a solvent or the like.
Moreover, you may add a fluororesin, a silicone resin, etc. to uncured ionizing radiation curable resin.
When the uncured ionizing radiation curable resin is cured by ultraviolet rays, it is preferable to add a photopolymerization initiator such as acetophenones and benzophenones to the uncured ionizing radiation curable resin.

After coating the uncured liquid ionizing radiation curable resin, the substrate may be irradiated with ionizing radiation after a substrate made of resin, glass or the like is bonded. Irradiation with ionizing radiation may be carried out from either the substrate or the light diffusing sheet having ionizing radiation transparency.

The thickness of the ionizing radiation curable resin sheet after curing is preferably about 0.1 to 100 μm. If the thickness of the ionizing radiation curable resin sheet after curing is 0.1 μm or more, sufficient strength can be secured, and if it is 100 μm or more, sufficient flexibility can be secured.

In the method shown in FIG. 6, the light diffusing sheet has a web shape, but it may be a sheet. In the case of using a single sheet, a stamp method using a single sheet as a flat plate mold, a roll imprint method using a single sheet wound around a roll as a cylindrical mold, and the like can be applied. Moreover, you may arrange | position the said light-diffusion sheet of a sheet | seat inside the type | mold of an injection molding machine.

In the methods (b) and (e), examples of the liquid thermosetting resin include uncured melamine resin, urethane resin, and epoxy resin.
The curing temperature in the method (b) is preferably lower than the glass transition temperature of the light diffusion sheet. This is because if the curing temperature is equal to or higher than the glass transition temperature of the light diffusing sheet, the uneven pattern of the light diffusing sheet may be deformed during curing.

In the methods (c) and (f), examples of the thermoplastic resin include acrylic resin, polyolefin, polyester, and the like.
The pressure when pressing the sheet-like thermoplastic resin on the process sheet is preferably 1 to 100 MPa. If the pressure at the time of pressing is 1 MPa or more, the concavo-convex pattern can be transferred with high accuracy, and if it is 100 MPa or less, excessive pressurization can be prevented.
Moreover, it is preferable that the heating temperature of the thermoplastic resin in the method (c) is lower than the glass transition temperature of the light diffusion sheet. It is because the uneven | corrugated pattern of the said light-diffusion sheet may deform | transform at the time of heating that heating temperature is more than the glass transition temperature of the said light-diffusion sheet.
The cooling temperature after heating is preferably less than the glass transition temperature of the thermoplastic resin because the uneven pattern can be transferred with high accuracy.

Among the methods (a) to (c), the method (a) using an ionizing radiation curable resin is preferable in that heating can be omitted and deformation of the uneven pattern of the light diffusion sheet can be prevented.

In the methods (d) to (f), the thickness of the process sheet is preferably about 50 to 500 μm. If the thickness of the process sheet is 50 μm or more, the process sheet has sufficient strength, and if it is 500 μm or less, sufficient flexibility can be secured.
In the methods (d) to (f), since a process sheet having a small deformation due to heat is used as a process sheet, any of an ionizing radiation curable resin, a thermosetting resin, and a thermoplastic resin is used as a material for the light diffusion sheet. Can be used.

In addition, in (d)-(f), the uneven | corrugated pattern of the said light-diffusion sheet was transcribe | transferred to the metal, and the process sheet was obtained, but you may transcribe | transfer to resin and may obtain a process sheet. Examples of the resin that can be used in this case include polycarbonate, polyacetal, polysulfone, and ionizing radiation curable resin used in the method (a). When using an ionizing radiation curable resin, similarly to the method (a), coating, curing, and peeling of the ionizing radiation curable resin are sequentially performed to obtain a process sheet.

The light diffusion sheet or light diffuser of the present invention may be provided with a pressure-sensitive adhesive layer on the surface opposite to the surface on which the concavo-convex pattern is formed.

Hereinafter, the present invention will be described in detail with reference to production examples. However, the present invention is not limited to the following description.

(Production Example 1)
Polystyrene (Polymer Source Co., Ltd.) diluted with toluene on one side of a 60 μm thick continuous sheet-like polyethylene terephthalate shrink film (trade name HIPIPET, manufactured by Mitsubishi Plastics, Inc.) that heat shrinks the most in the width direction as the heat shrinkable film Manufactured and having a glass transition temperature of 100 ° C.) was applied by a coating machine so as to have a thickness of 0.7 μm, and a hard layer was formed to obtain a laminated sheet.
A laminated sheet sample of 50 cm square of the obtained laminated sheet was cut out, the width direction in which the heat shrinkage was the largest was determined as the X direction, and both ends in the X direction and both ends in the Y direction of the laminated sheet sample were gripped.
At this time, as shown in FIGS. 7 and 8, the gripping means 33 for gripping both ends in the Y direction extends in the X direction in order to be movable in the X direction in accordance with the heat shrinkage in the X direction of the laminated sheet. The gripping means was attached every 8 cm in the X direction so as to be movable on a linear rail. Further, as shown in FIGS. 7 and 8, a means for detecting and controlling the tension in the X direction and the Y direction is arranged.
Next, the length before heating in the X direction by heating at 100 ° C. for 1 minute while applying tension to the laminated sheet so that the tension applied in the X direction of the laminated sheet is 30 times the tension applied in the Y direction. 40% (ie, shrink at a shrinkage rate of 60%), and shrink to 94% of the length before heating in the Y direction (ie, shrink at a deformation rate of 6%). A light diffusing sheet having a wavy uneven pattern along a direction perpendicular to the large shrinkage direction was obtained.

(Production Example 2)
In Production Example 1, before heating in the X direction by heating at 85 ° C. for 1 minute while applying tension to the laminated sheet so that the tension applied in the X direction of the laminated sheet is 20 times the tension applied in the Y direction. Except for heat shrinking to 60% of the length (ie shrinking at a shrinkage rate of 40%) and shrinking to 87% of the length before heating in the Y direction (ie shrinking at a deformation rate of 13%) In the same manner as in Production Example 1, a light diffusion sheet was obtained.

(Production Example 3)
In Production Example 1, heating was performed at 85 ° C. for 1 minute and 20 seconds while applying tension to the laminated sheet so that the tension applied in the X direction was 25 times the tension applied in the Y direction. Except for heat shrinking to 50% of the length (ie shrinking at a shrinkage rate of 50%) and shrinking to 92% of the length before heating in the Y direction (ie shrinking at a deformation rate of 8%), A light diffusion sheet was obtained in the same manner as in Production Example 1.

(Production Example 4)
In Production Example 1, by heating at 100 ° C. for 1 minute and 20 seconds while applying tension to the laminated sheet so that the tension applied in the X direction of the laminated sheet is 5 times the tension applied in the Y direction, Heat-shrink to 80% of the length before heating (ie, shrink at a shrinkage rate of 20%), and heat-shrink to 85% of the length before heating in the Y direction (ie, shrink at a shrinkage rate of 15%). Except that, a light diffusion sheet was obtained in the same manner as in Production Example 1.

(Production Example 5)
A biaxial heat-shrinkable film that heat-shrinks almost equally in the width direction and the flow direction is used as the heat-shrinkable film, and it is heat-deformed without gripping both ends in the X direction and both ends in the Y direction of the laminated sheet. Except for the above, a light diffusion sheet was obtained in the same manner as in Production Example 1.

(Evaluation method)
(1) Determination of average pitch and average depth Measure any 10 locations on the surface of the light diffusing sheet of Production Examples 1 to 5 with an atomic force microscope (Nanoscope III manufactured by Nihon Beco). The average pitch and average depth of the concavo-convex pattern were obtained.

(2) Evaluation of light diffusion characteristics [Measurement of 1/10 width in illuminance curve]
With respect to the light diffusing sheets of Production Examples 1 to 5, the light from the LED light source with an irradiation angle of 3.5 degrees from the surface on which the concave / convex pattern of the light diffusing sheet is formed is the axis where the emission luminance of the LED light source is highest. Were incident perpendicular to the surface of the light diffusion sheet.
Next, an illuminance curve was obtained by measuring transmitted scattered light using a goniometer (model: GENESIA Gonio / FFP, manufactured by Genesia). Specifically, the relative illuminance when the illuminance of light vertically emitted from the light diffusion sheet (the light emission angle of this light is 0 °) is 1, the light emission angle −90 along the X or Y direction. The relative illuminance from ° to 90 ° was measured at 1 ° intervals to obtain an illuminance curve. Here, the illuminance curve is a curve plotted as shown in FIG. 5 with the horizontal axis as the light emission angle and the vertical axis as the relative illuminance.
Then, a 1/10 value width (W2 in FIG. 5) in the illuminance curve was obtained. At that time, only data in an angle range where the relative illuminance was 0.1 or more was used.
Table 1 shows the results of the 1/10 value range. In addition, a diffusion angle becomes large, so that the angle of 1/10 value width of an illumination intensity curve is large.

(3) Characteristic when used for illumination The LED light source was installed in the center of the ceiling of the hallway, and the light diffusion sheets of Production Examples 1 to 5 were arranged so as to cover the LED light source. At this time, the light diffusion sheet is arranged so that the uneven surface is on the LED light source side, and the direction in which the 1/10 value diffusion angle measured in (2) is the largest is the length of the corridor. The light diffusing sheet was arranged so as to be in the direction. Next, the LED light source was turned on, and the illumination state of the hallway was visually observed according to the following criteria.
(Illuminance uniformity in the longitudinal direction of the corridor)
○: Widely and uniformly illuminated in the longitudinal direction of the corridor.
X: Not widely illuminated in the longitudinal direction of the corridor or not illuminated uniformly.
(Adjustment of illuminance on the corridor wall)
○: The corridor wall surface is uniformly illuminated to the extent that it is not too bright.
X: The wall surface of a hallway is too dazzling or is not illuminated uniformly.

The obtained light diffusion sheet was evaluated by the above-described evaluation method. The results are shown in Table 1.

All of the light diffusion sheets obtained from Production Example 1 to Production Example 4 have a range in which the 1/10 value diffusion angle in the X direction is 70 to 80 degrees and the 1/10 value diffusion angle in the Y direction is 5 to 15 degrees. It was a light diffusing sheet suitable for lighting in hallways and passages.

The production method of the present invention can provide a light diffusion sheet or a light diffuser light diffusion sheet having excellent anisotropic light diffusion characteristics.

It is sectional drawing which shows the lamination sheet in one Embodiment of the manufacturing method of the light-diffusion sheet of this invention. It is an expansion perspective view which expands and shows a part of one embodiment of the light diffusion sheet of the present invention. It is a figure which shows the heating deformation method in one Embodiment of the manufacturing method of the light-diffusion sheet of this invention. It is a figure which shows the heating deformation method which added the widening process in one Embodiment of the manufacturing method of the light-diffusion sheet of this invention. It is sectional drawing at the time of cut | disconnecting the light-diffusion sheet | seat of FIG. 2 in the orthogonal direction with the formation direction of an uneven | corrugated pattern. It is a figure explaining an example of the manufacturing method of the optical element using the light-diffusion sheet of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram (before heating deformation) illustrating an embodiment of the present invention. It is a conceptual diagram (after heating deformation) explaining the Example of this invention.

10 Light diffusion sheet 10a Laminated sheet 11 Heat shrinkable film 12 Hard layer 12a Hard layer with smooth surface (surface smooth hard layer)
13 Concavity and convexity pattern 13b Bottom 32 Holding means 33 Holding means 52 Tension detection and control means 53 Tension detection and control means

Claims (7)

At least one hard layer is laminated on one side of the heat-shrinkable film to produce a laminated sheet, and by heating and deforming the laminated sheet, at least the hard layer of the laminated sheet is meandered and deformed. An uneven pattern forming step of forming unevenness on the surface of the layer, and a method of manufacturing a light diffusion sheet,
When the direction along the surface of the laminated sheet is defined as the X direction and the direction along the surface of the laminated sheet and perpendicular to the X direction is defined as the Y direction, tension is applied at least in the Y direction in the concavo-convex pattern forming step. It is contracted so that the 1/10 value diffusion angle of the light incident on the light diffusion sheet from the surface on which the hard layer is laminated is 70 to 80 degrees in the X direction and 5 to 15 degrees in the Y direction. A method for producing a light diffusion sheet. At least one hard layer is laminated on one side of the heat-shrinkable film to produce a laminated sheet, and by heating and deforming the laminated sheet, at least the hard layer of the laminated sheet is meandered and deformed. A master mold forming step for obtaining a master by forming a concavo-convex pattern on the surface of the layer, and a transfer mold having a concavo-convex pattern on one side by transferring the shape of the concavo-convex pattern formed on the surface of the hard layer to the resin composition And a transfer step, and a method for producing a light diffuser that obtains the transfer mold as a light diffuser,
When the direction along the surface of the laminated sheet is defined as the X direction and the direction along the surface of the laminated sheet and perpendicular to the X direction is defined as the Y direction, tension is applied at least in the Y direction in the concavo-convex pattern forming step. It is made to act, and it is made to shrink so that the 1/10 value diffusion angle of the light which entered the light diffuser from the surface where the hard layer was laminated may be 70 to 80 degrees in the X direction and 5 to 15 degrees in the Y direction. A method for producing a light diffuser. At least one hard layer is laminated on one side of the heat-shrinkable film to produce a laminated sheet, and by heating and deforming the laminated sheet, at least the hard layer of the laminated sheet is meandered and deformed. A primary master mold forming step of forming a concave / convex pattern on the surface of the layer to obtain a primary master block, and the concave / convex pattern formed on the surface of the hard layer are applied to the resin composition or the metal composition 1 to n times (described above) n is an integer of 2 or more) 2- (n + 1) -order master mold forming step to obtain a 2- (n + 1) -order master mold having a concavo-convex pattern on one side, and the 2- (n + 1) -order master mold A method for producing a light diffusing body, comprising a step of producing a replica having a concavo-convex pattern transferred to another resin composition to obtain a replica having the concavo-convex pattern on one side, wherein the replica is obtained as a light diffusing body. ,
When the direction along the surface of the laminated sheet is defined as the X direction and the direction along the surface of the laminated sheet and perpendicular to the X direction is defined as the Y direction, tension is applied at least in the Y direction in the concavo-convex pattern forming step. It is made to act, and it is made to shrink so that the 1/10 value diffusion angle of the light which entered the light diffuser from the surface where the hard layer was laminated may be 70 to 80 degrees in the X direction and 5 to 15 degrees in the Y direction. A method for producing a light diffuser. The convex-concave in the pattern forming step, the action of tension in the X and Y directions, a method of manufacturing an optical diffusion sheet according to claim 1. The method for producing a light diffuser according to claim 2 or 3, wherein tension is applied in the X direction and the Y direction in the uneven pattern forming step. The average pitch of the concavo-convex pattern is adjusted to 1 to 20 [mu] m, the manufacturing method of the light diffusing sheet according to claim 1 or 4 as measured along the Y direction of the light diffusing sheet. The manufacturing method of the light diffuser in any one of Claim 2, 3 and 5 which adjusts the average pitch of the said uneven | corrugated pattern when measuring along the Y direction of the said light diffuser to 1-20 micrometers.

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