JP2016148792A - Method of manufacturing optical sheet laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical sheet laminate that has superior bonding strength between a first optical sheet and a second optical sheet.SOLUTION: A method of manufacturing an optical sheet laminate comprises: an adhesive layer arranging process (P1) of arranging an adhesive layer 30 formed of a resin solution prepared by mixing a crosslinking agent and a tackiness agent together on a lower surface 12 of a first optical sheet 10; an adhesive layer activation processing process (P2) of subjecting the adhesive layer 30 to activation processing; a prism surface activation processing process (P3) of subjecting a prism surface 21 of a second optical sheet 20 to activation processing; a laminating process (P4) of laminating the first optical sheet 10 on the second optical sheet 20 so that apexes of the prism surface 21 having been subjected to the activation processing are embedded in the adhesive layer 30 having been subjected to the activation processing until a gel fraction of the adhesive layer 30 reaches 30 mass%; and a uniting process (P5) of uniting the first optical sheet 10 and second optical sheet 20 together after the optical sheets are left until the gel fraction of the adhesive layer 30 reaches 60 mass% or higher.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing an optical sheet laminate formed by bonding a first optical sheet and a second optical sheet.

  The liquid crystal display device mainly includes a backlight portion and a liquid crystal display element portion. As the backlight unit, an edge light system in which a light source is disposed on the side surface of the light guide sheet is often used from the viewpoint of making the liquid crystal display device compact.

  A general edge-light type backlight unit includes a light source, a light source disposed on a side surface, a light guide sheet that guides and emits light from the light source, and a rear surface side of the light guide sheet. Reflecting sheet that reflects light leaked from the sheet, disposed on the exit surface side of the light guide sheet, condensing sheet that collects the light emitted from the light guide sheet, and disposed on the exit surface side of the condensing sheet, And a diffusion sheet for diffusing light emitted from the light collecting sheet.

  The light collecting sheet refracts the light emitted from the light guide sheet by the prism, condenses the light toward the liquid crystal panel side of the liquid crystal display element unit, and increases the luminance in the vertical direction of the liquid crystal panel surface.

  As such a condensing sheet, Patent Document 1 discloses an optical sheet laminate formed by joining two prism sheets having an exit surface which is an uneven prism surface. The optical sheet laminate includes a first optical sheet disposed on the exit side and a second optical sheet disposed on the incident side, and the second optical sheet is disposed on the adhesive layer provided on the lower surface of the first optical sheet. The top of the prism surface of the sheet is embedded and bonded together, so that the layers are integrated.

JP 2013-120394 A

  In such an optical sheet laminate, since only the top of the prism surface is embedded and bonded to the adhesive layer, the bonding strength is weak when the contact area between the adhesive layer and the prism surface is small, and the first optical In some cases, the sheet and the second optical sheet peel off.

  Then, this invention was made | formed in order to solve the said subject, The objective is to provide the manufacturing method of the optical sheet laminated body which is excellent in the joining strength of a 1st optical sheet and a 2nd optical sheet. is there.

Specific means for achieving the above-described problems are as follows.
A first optical sheet having an adhesive layer on the lower surface and a second optical sheet having an upper surface that is an uneven prism surface are laminated and integrated in a state where the top of the prism surface is embedded in the adhesive layer. A method for producing an optical sheet laminate,
An adhesive layer disposing step of disposing an adhesive layer formed by applying a resin solution containing a crosslinking agent and an adhesive on the lower surface of the first optical sheet;
An adhesion layer activation treatment step of performing at least one activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment and corona treatment on the adhesion layer;
A prism surface activation treatment step of performing at least one kind of activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment and corona treatment on the prism surface;
The reaction between the cross-linking agent and the pressure-sensitive adhesive proceeds, and before the gel fraction of the pressure-sensitive adhesive layer reaches 30% by mass, the top surface of the prism surface on which the pressure-sensitive adhesive layer has been activated is activated. Laminating step of laminating the first optical sheet on the second optical sheet so as to embed
After the laminating step, an integrated step of allowing the gel layer of the adhesive layer to stand until the gel fraction reaches 60% by mass or more and integrating the first optical sheet and the second optical sheet. Production method.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical sheet laminated body which is excellent in the joining strength of a 1st optical sheet and a 2nd optical sheet can be provided.

The flowchart which shows the manufacturing method of the optical sheet laminated body which concerns on embodiment of this invention. Schematic which shows the manufacturing method of the optical sheet laminated body which concerns on embodiment of this invention. Sectional drawing which shows the structure of the optical sheet laminated body manufactured by the manufacturing method of the optical sheet laminated body which concerns on embodiment of this invention.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to.

  FIG. 1 is a flowchart showing a method for manufacturing an optical sheet laminate according to an embodiment of the present invention. FIG. 2 is a schematic view showing a method for producing an optical sheet laminate according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing the configuration of the optical sheet laminate produced by the method for producing an optical sheet laminate according to the embodiment of the present invention.

In this specification, the term “step” is not limited to an independent step, and is included in this term if the purpose of the step is achieved even when it cannot be clearly distinguished from other steps.
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

<Method for producing optical sheet laminate>
The manufacturing method of the optical sheet laminated body 1 of the present invention includes the following steps (P1) to (P5).
(P1): Adhesive layer arrangement step (P2) of arranging an adhesive layer 30 formed by applying a resin solution containing a crosslinking agent and an adhesive on the lower surface 12 of the first optical sheet 10: In the adhesive layer 30 Adhesion layer activation treatment step (P3) for performing at least one kind of activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment and corona treatment: Plasma treatment and excimer treatment on the prism surface 21 of the second optical sheet 20 Prism surface activation treatment step (P4) for performing at least one kind of activation treatment selected from ultraviolet irradiation treatment and corona treatment: The reaction between the crosslinking agent and the pressure-sensitive adhesive proceeds, and the gel fraction of the pressure-sensitive adhesive layer 30 is 30% by mass. The first optical sheet 10 is laminated on the second optical sheet 20 so as to embed the top of the activated prism surface 21 in the activated adhesive layer 30 before reaching That the lamination step (P5): allowed to stand until the gel fraction of the adhesive layer 30 reaches 60% by mass or more, integration step of integrating the first optical sheet 10 and the second optical sheet 20

In the method for producing the optical sheet laminate 1 of the present invention, the adhesive layer 30 and the prism surface 21 are activated before the gel fraction of the adhesive layer reaches 30% by mass, and the top of the prism surface 21 is adhered. Embedded in the layer.
Therefore, the activation process is performed in a state where the crosslinking reaction is not progressing, that is, in a state where the elasticity of the adhesive layer 30 is low, and the activated prism surface 21 and the adhesive layer 30 are brought into contact with each other. The wettability of the adhesive layer 30 is improved. Thereafter, the cross-linking reaction of the adhesive layer 30 proceeds and the cohesive force increases, whereby the prism surface 21 and the adhesive layer 30 are firmly bonded.
Therefore, the optical sheet laminate 1 manufactured by the manufacturing method of the present invention can firmly bond the first optical sheet 10 and the second optical sheet 20.

<Adhesive layer placement process>
In the pressure-sensitive adhesive layer arranging step (P1) of the present invention, the pressure-sensitive adhesive layer 30 formed by applying a resin solution containing a crosslinking agent and a pressure-sensitive adhesive to the lower surface 12 of the first optical sheet 10 is arranged.
As a method for arranging the pressure-sensitive adhesive layer 30, a resin solution in which a crosslinking agent and a pressure-sensitive adhesive are blended is applied to the lower surface 12 of the first optical sheet 10, dried, and directly arranged, or a surface-treated peeling with a release agent. Examples include a method in which a resin solution is applied to a film and dried to form an adhesive layer, and the adhesive layer is attached to the lower surface 12 of the first optical sheet 10 and then disposed by peeling off the release film.

  The pressure-sensitive adhesive contained in the resin solution forming the pressure-sensitive adhesive layer 30 is not particularly limited as long as it is a pressure-sensitive adhesive, but acrylic pressure-sensitive adhesive, ethylene-vinyl acetate copolymer-based pressure-sensitive adhesive, natural rubber-based pressure-sensitive adhesive, synthetic Various pressure-sensitive adhesives such as a rubber-based pressure-sensitive adhesive, a polyurethane-based pressure-sensitive adhesive, and a polyester-based pressure-sensitive adhesive can be exemplified.

The pressure-sensitive adhesive is more preferably an acrylic pressure-sensitive adhesive from the viewpoint of transparency and adhesiveness with the optical sheet.
The acrylic pressure-sensitive adhesive has, as a base polymer, a (meth) acrylic polymer having a main skeleton of a monomer unit of (meth) acrylic acid alkyl ester having an alkyl group with an average carbon number of about 3 to 9. (Meth) acrylic polymers are copolymerized with carboxy group-containing monomers such as (meth) acrylic acid, hydroxy group-containing monomers such as hydroxyalkyl (meth) acrylate, and other functional monomers as copolymerization monomers. can do.

  The crosslinking agent contained in the resin solution forming the adhesive layer 30 is not particularly limited as long as it crosslinks with the functional group of the adhesive, but is not limited to an isocyanate crosslinking agent, an amine crosslinking agent, a melamine crosslinking agent, urea. Various cross-linking agents such as a system cross-linking agent, an epoxy-based cross-linking agent, and a metal chelate-based cross-linking agent can be exemplified. The crosslinking agent is more preferably an isocyanate-based crosslinking agent from the viewpoint of adhesiveness with the optical sheet.

  The resin solution which forms the adhesion layer 30 may contain another component as needed. Examples of other components include a crosslinking catalyst, a chelating agent, a weather resistance stabilizer, a tackifier, a plasticizer, a softening agent, a dye, a pigment, and an inorganic filler.

<Adhesion layer activation treatment process>
In the adhesion layer activation treatment step (P2) of the present invention, the adhesion layer 30 is subjected to at least one activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment, and corona treatment.

The plasma treatment is a treatment in which the first optical sheet 10 (adhesive layer 30) is placed in a container containing air, oxygen, nitrogen, carbon dioxide, argon, neon, etc., and exposed to plasma generated by glow discharge. This can be performed by discharging in a normal pressure air or an inert gas atmosphere using a plasma processing machine.
The excimer process is a process of irradiating the light from the excimer lamp to the first optical sheet 10 (adhesive layer 30). After the first optical sheet 10 (adhesive layer 30) is disposed in the container, the excimer process is performed in an oxygen gas atmosphere. It can be performed by irradiating excimer light.
The ultraviolet irradiation process is a process of irradiating high-energy ultraviolet rays to generate radicals of the atmospheric gas and cutting bonds between molecules on the surface of the first optical sheet 10 (adhesive layer 30) by the energy of the ultraviolet rays.
The corona treatment is a treatment for allowing the first optical sheet 10 (adhesive layer 30) to pass through an electric field in which corona discharge occurs, and can be performed, for example, by discharging in normal pressure air using a corona treatment machine. it can.

  The activation treatment of the present invention is preferably a corona treatment from the viewpoint of treatment efficiency.

<Prism surface activation process>
In the prism surface activation treatment step (P3) of the present invention, the prism surface 21 of the second optical sheet 20 is subjected to at least one activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment, and corona treatment.

  The activation processing method of the second optical sheet 20 (prism surface 21) is the same as that of the adhesive layer 30 (first optical sheet 10).

<Lamination process>
In the lamination step (P4) of the present invention, the reaction between the crosslinking agent and the pressure-sensitive adhesive proceeds, and the pressure-sensitive adhesive layer 30 that has been activated is activated before the gel fraction of the pressure-sensitive adhesive layer 30 reaches 30% by mass. The 1st optical sheet 10 is laminated | stacked on the 2nd optical sheet 20 so that the top part of the processed prism surface 21 may be embedded.

  As for the gel fraction of the adhesion layer 30 in a lamination process (P4), it is more preferable that it is 20 mass% or less. When the content is 20% by mass or less, the wettability of the adhesive layer 30 to the prism surface 21 is further improved.

The gel fraction of the adhesive layer is calculated from the following formula by performing the following operations (1) to (3).
Gel fraction (mass%) = [(Z−X) / (Y−X)] × 100
In the formula, X is the mass (g) of the wire mesh, Y is the mass of the sample for extraction (total mass of the adhesive layer and the wire mesh) (g), and Z is the mass of the sample for extraction dried after immersion (g). The total mass of insoluble matter in the wire mesh and the adhesive layer) (g).

(1) A finely weighed 250 mesh wire mesh (100 mm × 100 mm) is pasted with the material collected from the adhesive layer 30 formed on the lower surface 12 of the first optical sheet 10 and wrapped with a wire mesh to obtain a sample for extraction. The mass of the sample for extraction (the total mass of the adhesive layer and the wire mesh) is measured with a precision balance.
(2) A sample for extraction is placed in a glass bottle containing 80 g of ethyl acetate as an extraction solvent and immersed for 3 days.
(3) After completion of immersion, the sample for extraction is taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. The mass of the sample for extraction after drying (the total mass of insolubles in the wire mesh and the adhesive layer) is measured with a precision balance.

<Integration process>
In the integration step (P5) of the present invention, after the lamination step, the first optical sheet 10 and the second optical sheet 20 are integrated by leaving until the gel fraction of the adhesive layer 30 reaches 60% by mass or more. Thus, an optical sheet laminate is obtained.

  As for the gel fraction of the adhesion layer 30 in an integration process (P5), it is more preferable that it is 80 mass% or more. When it is 80% by mass or more, the bonding strength between the first optical sheet 10 and the second optical sheet 20 is further improved.

<Optical sheet laminate>
The optical sheet laminate 1 produced by the production method of the present invention is a sheet laminate in which a first optical sheet 10 and a second optical sheet 20 are joined together by an adhesive layer 30 as shown in FIG. The top of the prism surface 21 (upper surface 21) of the second optical sheet 20 is embedded in the adhesive layer 30 provided on the lower surface 12 of the first optical sheet 10. Further, the bottom of the prism surface 21 is not in contact with the adhesive layer 30, and the lower surface of the adhesive layer 30 and the upper surface 21 of the second optical sheet 20 are surrounded between the adhesive layer 30 and the second optical sheet 20. A void 40 is formed.

  The optical sheet laminate 1 of the present invention functions as a condensing sheet, and propagates light incident from the lower surface 22 of the second optical sheet 20 along the thickness direction and exits from the upper surface 11 of the first optical sheet 10. .

<First optical sheet>
In the first optical sheet 10, a large number of prism elements 13 are formed on the upper surface 11 side which is a light emission surface, the upper surface 11 is an uneven prism surface, and the lower surface 12 is a flat surface. The light emitted from the upper surface 21 of the second optical sheet 20 enters the lower surface 12 of the first optical sheet 10, propagates along the thickness direction, and exits from the upper surface 11 of the first optical sheet 10.

  The shape of the prism element 13 is not particularly limited, and examples thereof include a linear triangular prism, a linear Fresnel prism, a semispherical prism, a triangular pyramid prism, and a quadrangular pyramid prism.

  The total thickness of the first optical sheet 10 is not particularly limited, but is preferably 10 to 500 μm, and more preferably 20 to 250 μm. The height of the prism element 13 is not particularly limited, but is preferably 1 to 50 μm, and more preferably 5 to 30 μm.

  The first optical sheet 10 is made of a light transmissive material. Such a material is not particularly limited as long as it is a light-transmitting material. However, acrylic resin, polycarbonate resin, polyester resin, polystyrene resin, polyvinyl chloride resin, fluororesin, polyolefin resin, cellulose acetate resin, silicone-based material Examples thereof include resins such as resins, polyamide resins, epoxy resins, polyacrylonitrile resins, and polyurethane resins.

  As a manufacturing method of the first optical sheet 10, a sheet-shaped resin material extruded from a die is pressed between a transfer roller and a nip roller, and the unevenness on the surface of the transfer roller is transferred to the resin material. A method of laminating a plate and a resin sheet and press-molding by thermal transfer, a method of curing by irradiation with radiation while transferring the unevenness of the surface of the uneven roller to the coating layer coated with radiation-curing resin on the surface of the transparent film, etc. It is done.

<Adhesive layer>
The adhesive layer 30 is provided on the lower surface 12 of the first optical sheet 10.
Although the thickness of the adhesion layer 30 is not specifically limited, It is preferable that it is 2-20 micrometers, and it is more preferable that it is 2-5 micrometers.

<Second optical sheet>
In the second optical sheet 20, a large number of prism elements 23 are formed on the upper surface 21 side which is a light emission surface, the upper surface 21 is an uneven prism surface, and the lower surface 22 is a flat surface. Light incident from the lower surface 22 of the second optical sheet 20 propagates along the thickness direction and exits from the upper surface 21 of the second optical sheet 20.

  The shape of the prism element 23 is not particularly limited, and examples thereof include a linear triangular prism, a linear Fresnel prism, a semispherical prism, a triangular pyramid prism, and a quadrangular pyramid prism.

  The overall thickness of the second optical sheet 20 is not particularly limited, but is preferably 10 to 500 μm, and more preferably 20 to 250 μm. The height of the prism element 23 is not particularly limited, but is preferably 1 to 50 μm, and more preferably 5 to 30 μm.

  Examples of the material and manufacturing method of the second optical sheet 20 include the same materials and manufacturing methods as those of the first optical sheet 10.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples. Unless otherwise specified, “part” and “%” are based on mass.

[Preparation of materials]
<Manufacture of adhesives>
A reactor equipped with a stirrer, reflux condenser, sequential dropping device, thermometer, 25% by mass of a monomer mixture consisting of 99 parts of butyl acrylate (BA) and 1 part of acrylic acid (AA), ethyl acetate 45 parts and 0.01 part of azobisisobutyronitrile as a polymerization initiator were added and heated, and polymerization was carried out at reflux temperature for about 20 minutes. Subsequently, 75 mass% of the remaining amount of the monomer mixture and a polymerization initiator solution consisting of 13 parts of ethyl acetate and 0.13 part of azobisisobutyronitrile were successively added dropwise over about 120 minutes under reflux temperature conditions. Further 80 minutes later, 15 parts of toluene and 0.32 part of azobisisobutyronitrile were successively added dropwise over about 60 minutes, and the polymerization reaction was further carried out for 90 minutes. After completion of the reaction, the mixture was diluted with toluene to obtain a pressure-sensitive adhesive made of an acrylic copolymer.

<Preparation of resin solution for forming adhesive layer>
100 parts of the above pressure-sensitive adhesive solution (solid content: 44.6% by mass) is mixed with 0.3 part of an isocyanate-based crosslinking agent (Nissetsu CK-121, Nippon Carbide Industries, Ltd., solid content: 75% by mass). The solution was sufficiently stirred to obtain a resin solution for forming an adhesive layer.

<Manufacture of the first optical sheet>
Polycarbonate film (Mitsubishi Engineering Plastics Co., Ltd., Uniplus LC-320F, thickness: 75 μm), upper and lower molds having an uneven surface (inverted mold) and a lower mold having a mirror-like surface from both upper and lower sides And was subjected to heat molding at a temperature of 170 ° C. and a pressure of 10 MPa for 5 minutes to obtain a first optical sheet.
A linear triangular prism element having an apex angle of 90 ° and a height of 12 μm is arranged above the first optical sheet.

<Manufacture of the second optical sheet>
Polycarbonate film (Mitsubishi Engineering Plastics Co., Ltd., Uniplus LC-320F, thickness: 75 μm), upper and lower molds having an uneven surface (inverted mold) and a lower mold having a mirror-like surface from both upper and lower sides And was subjected to heat molding at a temperature of 170 ° C. and a pressure of 10 MPa for 5 minutes to obtain a second optical sheet.
On the upper side of the second optical sheet, linear triangular prism elements having an apex angle of 90 ° and a height of 22.5 μm and linear triangular prism elements having an apex angle of 90 ° and a height of 27.5 μm are alternately arranged in parallel. Yes.

[Method for producing optical sheet laminate]
<Adhesive layer placement process>
A pressure-sensitive adhesive layer-forming resin solution was applied to the lower surface of the first optical sheet so that the thickness after drying was 2 μm, and heat-dried at 100 ° C. for 2 minutes to form a pressure-sensitive adhesive layer.

<Adhesion layer activation treatment process>
Using a corona treatment device (Kasuga Denki Co., Ltd.) on the lower surface of the adhesive layer, two wire electrodes with an output of 400 W, a frequency of 44 kHz and a diameter of 17 mm, an electrode length of 450 mm, a work electrode distance of 2.0 mm, and a conveyance speed of 1 m / min. The discharge treatment was performed once under the conditions.

<Prism surface activation process>
Using a corona treatment device (manufactured by Kasuga Denki Co.), the prism surface of the second prism sheet is composed of two wire electrodes having an output of 400 W, a frequency of 44 kHz, and a diameter of 17 mm, an electrode length of 4450 mm, a work electrode distance of 2.0 mm, and a conveying speed. The discharge treatment was performed once under the condition of 1 m / min.

<Lamination process>
Three hours after mixing the cross-linking agent and the pressure-sensitive adhesive, the first optical sheet and the second optical sheet are used so that the pressure-sensitive adhesive layer and the prism surface of the second optical sheet face each other, and a rubber roller is used. To obtain an intermediate laminate.
The top of the prism surface is in contact with the lower surface of the first optical sheet through the adhesive layer. The arrangement directions of the prism elements of the first optical sheet and the second optical sheet are orthogonal to each other.

<Integration process>
The intermediate laminate was cured (stationary) for 4 days in an environment adjusted to a temperature of 23 ° C. and a humidity of 50% RH to obtain an optical sheet laminate in which the first optical sheet and the second optical sheet were integrated. .

<Measurement of gel fraction>
The gel fraction (mass%) of the adhesion layer at the time of a lamination process was measured by the method mentioned above. The results are shown in Table 1.
The gel fraction (% by mass) of the adhesive layer after the integration step is peeled off the first optical sheet and the second optical sheet after the integration step, and the adhesive layer remaining on the lower surface of the first optical sheet is scraped and collected. It was measured by the method described above. The results are shown in Table 1.

<Joint strength>
The bonding strength of the optical sheet laminate was evaluated by performing the following operations (1) to (3).
(1) The optical sheet laminate was cut into a width of 25 mm and a length of 150 mm, and one end was peeled off by about 10 mm by hand.
(2) A 25 mm wide double-sided tape was applied to the lower surface of the second optical sheet of the optical sheet laminate, and this was applied to an aluminum plate.
(3) Using a tensile tester (Orientec Co., Ltd., STA-1225), in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH, the one end of the first optical sheet peeled by about 10 mm was grasped, and the peel angle was 180 °. About 80 mm was peeled off at a peeling speed of 300 mm / min, and the peel adhesive strength (N / 25 mm) was measured. Then, the peel adhesive strength was determined as the bonding strength between the first optical sheet and the second optical sheet and evaluated according to the following evaluation criteria. The results are shown in Table 1.

<Evaluation criteria>
○: 0.750 N / 25 mm or more ×: less than 0.750 N / 25 mm

<Comparative Example 1>
A comparative example was carried out in the same manner as in Example 1 except that the laminating step was performed 30 hours after blending the cross-linking agent and the adhesive, and the gel fraction of the adhesive layer in the laminating step was changed as shown in Table 1. 1 optical sheet laminate was prepared.
The prepared optical sheet laminate was measured in the same manner as in Example 1 for gel fraction and bonding strength. The results are shown in Table 1.

  As shown in Table 1, the evaluation of the bonding strength of the optical sheet laminate of Example 1 was better than that of the optical sheet laminate of Comparative Example 1.

DESCRIPTION OF SYMBOLS 1 ... Optical sheet laminated body 10 ... 1st optical sheet 11 ... Upper surface (prism surface) of a 1st optical sheet
DESCRIPTION OF SYMBOLS 12 ... Lower surface of 1st optical sheet 13 ... Optical element of 1st optical sheet 20 ... 2nd optical sheet 21 ... Upper surface (prism surface) of 2nd optical sheet
22 ... lower surface of the second optical sheet 23 ... optical element of the second optical sheet 30 ... adhesive layer 40 ... gap

Claims (1)

An optical device in which a first optical sheet having an adhesive layer on the lower surface and a second optical sheet having an upper surface that is a concavo-convex prism surface are laminated and integrated in a state where the top of the prism surface is embedded in the adhesive layer A method for producing a sheet laminate,
An adhesive layer disposing step of disposing an adhesive layer formed by applying a resin solution containing a crosslinking agent and an adhesive on the lower surface of the first optical sheet;
An adhesion layer activation treatment step of performing at least one activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment and corona treatment on the adhesion layer;
A prism surface activation treatment step of performing at least one kind of activation treatment selected from plasma treatment, excimer treatment, ultraviolet irradiation treatment and corona treatment on the prism surface;
The reaction between the cross-linking agent and the pressure-sensitive adhesive proceeds, and before the gel fraction of the pressure-sensitive adhesive layer reaches 30% by mass, the top of the prism surface subjected to the activation treatment is applied to the pressure-sensitive adhesive layer that has been activated. A lamination step of laminating the first optical sheet on the second optical sheet so as to be embedded;
An integration step of integrating the first optical sheet and the second optical sheet by allowing the gel fraction of the adhesive layer to reach 60% by mass or more after the lamination step; Production method.

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