JPH07112490A - Production of optical sheet - Google Patents

Abstract

PURPOSE:To obtain an optical sheet having no strain in an uneven shape and enhanced in optical accuracy by irradiating the non-flowable resin layer consisting of a thermoplastic resin, an electromagnetic radiation curable monomer and a polymerization initiator formed on a sheet like transparent base material with electromagnetic radiation while bringing a roll having uneven surface into contact with the surface of the resin layer under pressure. CONSTITUTION:A non-flowable resin compsn. 3 consisting of a thermoplastic resin, an electromagnetic radiation curable monomer and a polymerization initiator is dissolved in a solvent to be cast on a sheet like transparent base material 2 and the solvent is evaporated to be removed. This laminate 1 is fed at a constant speed and the resin compsn. 3 is heated and softened by a heating means. The laminate 1 and a molding roll 6 having an uneven surface are pressed by a pressure contact roll 5 and the transparent base material is irradiated with electromagnetic radiation, from below to cure the resin compsn. By this constitution, an optical sheet wherein the uneven shape of the roll 6 is transferred to the resin compsn. layer 3 with high accuracy is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical sheet having a precise concave-convex shape on the surface thereof with a resin, such as a Fresnel lens sheet, a lenticular lens sheet, a triangular prism lens sheet.

[0002]

2. Description of the Related Art An optical sheet is involved in reflection and refraction of light, and it is necessary to manufacture it with accurate dimensional accuracy of an entrance surface, an exit surface, etc., without deteriorating optical properties. As a conventional method, there is a method of directly molding a liquid monomer, that is, a 2P (Photo Polymer) method. For example, a radiation-curable resin having fluidity is supplied between a roll having a concave-convex shape on the surface and a substrate film, these are pressure-contacted, and the resin is cured by irradiating ultraviolet rays from the outside, and a sheet To continuously produce a reflection tape or prism sheet having a resin uneven layer formed on a substrate film (US Pat. No. 3,689,346, US Pat. No. 4414).
No. 316, U.S. Pat. No. 4,420,527, Japanese Patent Publication No. 1-3.
5737 and Japanese Patent Publication No. 1-35838).

Further, a flowable photocurable resin composition in a monomer state is sandwiched between a pair of sandwiching members having a transparent portion on one side and one side inner surface of which mold irregularities are formed, There is a method of producing a prism sheet or the like by a batch method by exposing a resin composition to light through the transparent portion of the sandwich and curing the resin composition (JP-A-48-21546, etc.). In the 2P method, since the raw material form is liquid, even if the target uneven shape is required to be relatively complicated, the molding temperature and the molding pressure can be molded under relatively mild conditions. Further, since the molding can be completed in a short time by irradiation with electromagnetic radiation and the continuous production is possible, it is advantageous in terms of production cost and has been widely used in recent years.

[0004]

In the 2P method, since polymerization and molding are carried out directly from a liquid monomer, there is a problem that the polymerization shrinkage of the monomer lowers the accuracy of molding, or the resin layer and the substrate. It is difficult to manufacture an optical sheet that requires high precision because a minute gap may be generated between the layer and the layer and peeling may occur. Further, in the 2P method, since the raw material is a liquid, it is difficult to handle and it cannot be fixed on the surface of the base material, so that it is difficult to manufacture an optical sheet having a uniform thickness.

Moreover, the step of applying the monomer to the mold,
The shaping step of irradiating with electromagnetic radiation to form unevenness must be continuously performed, and the steps of coating a fluid material and polymerizing a monomer have to be performed in almost the same apparatus. For this reason, it is necessary to use an expensive or complicated device which has a low degree of freedom of work and which continuously performs coating and polymerization.

[0006]

In order to solve the conventional problems, the present invention has small polymerization shrinkage, excellent optical precision moldability, does not peel off, and has a good handleability of the molding material. The present invention provides a manufacturing method that has a high degree of freedom in work and does not require expensive or complicated equipment.

That is, according to the present invention, a non-fluid resin composition layer comprising a thermoplastic polymer, an electromagnetic radiation curable monomer and a polymerization initiator is formed on a sheet transparent substrate to form a sheet laminate. Then, the sheet-shaped laminate is heated to soften the resin composition layer, and immediately after that, the resin composition side of the laminate is placed in a roll-shaped die having a reverse shape of the target uneven shape on the surface. An optical sheet characterized by forming a concavo-convex resin layer on a transparent substrate by irradiating the resin composition layer with electromagnetic radiation through the transparent substrate while pressing it to cure the resin composition layer. It is a manufacturing method.

The present invention will be described in detail below. The resin composition comprises a thermoplastic polymer, an electromagnetic radiation curable monomer and a polymerization initiator. The resin composition is formed on a sheet-shaped transparent substrate and used as a two-layer sheet-shaped laminate. By including the polymer in the resin composition, the content rate of the monomer that causes the polymerization shrinkage is reduced, and as a result, the polymerization shrinkage of the entire resin composition can be reduced, and the lenticular lens such as an optical lens can be used. It is suitable for manufacturing optical sheets that require high accuracy. The layer of the resin composition formed on the sheet-shaped transparent substrate needs to have an appropriate thickness depending on the intended optical lens sheet.

Various methods are conceivable for producing a sheet-like laminate by forming a layer of the resin composition on the transparent substrate, but any method may be used. For example,
A method in which the resin composition is dissolved in a solvent to reduce the viscosity as a uniform solution, cast on a sheet-shaped transparent substrate using various coating methods, and passed through a drying oven to remove the solvent by evaporation (solution The casting method) is simple. Examples of the solvent include butyl acetate, ethyl acetate, methyl ethyl ketone, acetone, toluene, xylene, methanol, ethanol, isopropyl alcohol, n-propyl alcohol and the like. Examples of preferable coating methods include roll coaters, curtain coaters, flow coaters, lip coaters, doctor blade type coaters, and the like.

In the resin composition manufacturing process, the viscosity of the resin composition can be controlled as compared with the conventional 2P method, and there is an advantage that the resin composition having high viscosity can be easily handled. Alternatively, the resin composition may be uniformly mixed and heated to reduce the viscosity, and the resin composition may be coated on a sheet-shaped transparent substrate and then cooled and solidified. It is also possible to obtain the composition by uniformly mixing the composition, extruding the composition into a sheet by an extruder, pressing the sheet-like transparent substrate immediately after the extrusion with a nip roll, and then cooling and solidifying the composition.

The thermoplastic polymer is a polymer having a linear structure in terms of chemical structure and is not particularly limited. Representative examples of the polymer include polymethylmethacrylate, polyethylmethacrylate, polypropylmethacrylate, n-butylmethacrylate, i-butylmethacrylate, polyvinylacetate, polystyrene, polyethylene, polypropylene and copolymers thereof. Can be mentioned. These are used alone or as a mixture of two or more kinds.

The electromagnetic radiation-curable monomer has at least one (meth) acryloyl group in its molecule. Representative examples of the monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, and (meth). T-butyl acrylate, pentyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
N-hexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, butoxyethyl (meth) acrylate, allyl (meth) acrylate,
Methallyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate,
Cyclohexyl (meth) acrylate, norbornyl (meth) acrylate, isobornyl (meth) acrylate,
Adamantyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate,
3-phenoxy-2-hydroxypropyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, polyethylene glycol monoalkyl ether (meth) acrylate, polypropylene glycol monoalkyl ether (meth) acrylate, (meth) Mono (meth) acrylate compounds such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and phosphoethyl (meth) acrylate; polyethylene glycol di (meth) ) Acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth)
Di (meth) acrylate of polyethylene glycol such as acrylate, tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate; propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate,
Di (meth) acrylate of polypropylene glycol such as tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, nonapropylene glycol di (meth) acrylate;
1,3-butylene glycol di (meth) acrylate,
1,4-butylene glycol di (meth) acrylate,
1,6-hexamethylene glycol di (meth) acrylate, 1,9-nonamethylene glycol di (meth) acrylate, 1,14-tetradecamethylene glycol di (meth) acrylate, neopentyl glycol di (Meth) acrylate, neopentyl glycol hydroxypivalate di (meth) acrylate, di (meth) acrylate of a caprolactone adduct of neopentyl glycol hydroxypivalate, neopentyl glycol adipate di (meth) acrylate, Dicyclopentanyl di (meth) acrylate, dicyclopentanyl di (meth) acrylate
Acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth)
Acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, di (meth) acryloyloxyethyl isocyanurate, tris (meth) Acryloyloxyethyl ussianurate, 2,2-bis (4- (meth) acryloyloxyphenyl) -propane, 2,2-bis (4-
(Meth) acryloyloxyethoxyphenyl) -propane, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) -propane, 2,2-bis (4-
(Meth) acryloyloxypentaethoxyphenyl)
-Propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3,5-dibromophenyl) -propane, 2,2-bis (4- (meth) acryloyldiethoxy-3,5-dibromophenyl) -Propane, 2,2-
Bis (4- (meth) acryloylpentaethoxy-3,
5-dibromophenyl) -propane, 2,2-bis (4- (meth) acryloyloxyethoxy-3,5-
Dimethylphenyl) -propane, 2,2-bis (4-
(Meth) acryloyloxyethoxy-3-phenylphenyl) -propane, bis (4- (meth) acryloyloxyphenyl) -sulfone, bis (4- (meth) acryloyloxyethoxyphenyl) -sulfone, bis (4- (meth) ) Acryloyloxydiethoxyphenyl) -sulfone, bis (4- (meth) acryloyloxypentaethoxyphenyl) -sulfone, bis (4
-(Meth) acryloyloxyethoxy-3-phenylphenyl) -sulfone, bis (4- (meth) acryloyloxyethoxy-3,5-dimethylphenyl) -sulfone, bis (4- (meth) acryloyloxyethoxy-3, 5-dibromophenyl) -sulfone, bis (4- (meth) acryloyloxyphenyl) -sulfide, bis (4- (meth) acryloyloxyethoxyphenyl) -sulfide, bis (4- (meth) acryloyloxyethoxy-3- Phenylphenyl) -sulfide bis (4- (meth) acryloyloxyethoxy-
3,5-Dimethylphenyl) -sulfide, bis (4-
Polyfunctional (meth) acrylate compounds such as (meth) acryloyloxyethoxy-3,5-dibromophenyl) -sulfide, di ((meth) acryloyloxyethoxy) phosphate, tri ((meth) acryloyloxyethoxy) phosphate Can be mentioned. Other oligomers such as urethane (meth) acrylate and epoxy (meth) acrylate having at least one (meth) acryloyl group in the molecule can also be used. All of these are used alone or as a mixture of two or more kinds.

The electromagnetic radiation curable resin composition used in the present invention contains 1.67 to 167 parts by weight, preferably 4.18 to 120.5 parts by weight, more preferably
8.35-83.5 parts by weight of monomer, 2.33-23
3 parts by weight, preferably 4.66 to 166.5 parts by weight,
More preferably, 11.65 to 116.5 parts by weight of polymer are included.

The polymerization initiator is an initiator (photopolymerization initiator) which generates active radicals by electromagnetic radiation, and examples thereof include 2-hydroxy-2-methyl-1-phenylpropan-1-one, Hydroxycyclohexyl phenyl ketone, methyl phenyl glyoxylate, 2,
4,6-Trimethylbenzoyldiphenylphosphine oxide, benzyl dimethyl ketal and the like can be mentioned. The resin composition has adhesiveness, light resistance, antistatic property,
Etc. to improve other physical properties such as plasticizer, surfactant, antioxidant, ultraviolet absorber, antistatic agent, lubricant, colorant, filler, release agent, etc. within the range not impairing the object of the present invention. You may add. As a sheet-shaped transparent substrate that can be used for the sheet-shaped material, a transparent sheet made of transparent inorganic glass or a transparent thermoplastic resin can be used. It is desirable to have flexibility in consideration of continuous production of molded products. Further, an easily adhesive layer and an antistatic layer may be provided if necessary. As the transparent thermoplastic resin, for example,
Mention may be made of polymethylmethacrylate, polycarbonate, polyethylene terephthalate (PET) and their copolymers.

In the present invention, the coating step and the step of forming the laminated body can be carried out continuously with the step of forming the cured uneven resin layer on the transparent substrate, but the coating step and the laminating step are also possible. After the step of forming the body, it is possible to divide the manufacturing process by pasting a protective film on the non-fluid resin composition layer and winding it up, so that the flexibility of the process is great. Have.

In the present invention, since there is a degree of freedom in the above-mentioned work, a continuous film may be used as a transparent base material and continuously applied or cured, but a plurality of transparent base materials or laminates may be used. It can also be manufactured in a batch method using a sheet. In the present invention, in order to cure the resin composition, an electron beam, an ion beam, a particle beam such as an ion beam,
Electromagnetic radiation such as gamma rays, X-rays, ultraviolet rays and visible rays are used.

[0017]

The method of manufacturing an optical sheet according to the present invention having the above-described structure exhibits the following functions. First, a sheet-shaped laminate having a non-fluid resin composition layer composed of a thermoplastic polymer, an electromagnetic radiation-curable monomer, and a polymerization initiator, and a sheet-shaped transparent substrate is formed. In the step of forming the laminate, the viscosity of the resin composition can be controlled as compared with the conventional 2P method, and there is also an advantage that the resin composition having high viscosity can be easily handled. Although it is possible to continuously perform the step of forming the laminate and the step of irradiating the electromagnetic radiation, after the step of forming the laminate, a protective film is attached onto the non-fluid resin composition layer and wound up. It is also possible to divide the manufacturing process by carrying out, and there is also an advantage that the degree of freedom regarding the process is large.

Next, when the laminate is heated, the resin composition layer is softened. Immediately after softening, when the resin composition layer side is pressed against a roll having a mold on its surface, the softened resin layer is pressed into the mold to form irregularities. When the resin composition layer is irradiated with electromagnetic radiation through the transparent substrate at the same time as the pressure contact, the resin composition layer is cured to form a desired uneven shape. By including the polymer in the resin composition layer, the content of the monomer that causes the polymerization shrinkage is reduced, and as a result, the polymerization shrinkage of the entire resin composition layer can be reduced, and the optical It is suitable for manufacturing optical sheets that require high accuracy.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the accompanying drawings. Numbers in parentheses are% by weight.

[Example of Apparatus] An example of an apparatus used in the method for producing an optical sheet according to the present invention is shown in FIG. In FIG. 1, the laminate 1 is composed of a transparent base material 2 and a resin composition layer 3, and is conveyed at a constant speed by a conveying means (not shown). The resin composition 3 is heated by the heating means 4 to soften the laminate 1. On the downstream side of the laminated body 1 to be conveyed,
A forming roll 6 having a reverse concavo-convex shape to the target concavo-convex shape is provided on the surface, and rotates at the same speed as the laminate 1. The press roll 5 adjacent to and interlocking with the forming roll 6 presses the laminate 1 and the forming roll 6 together. Forming roll 6
The electromagnetic radiation irradiating device 7 disposed below the transparent substrate 2 irradiates the transparent substrate 2 from below. Since the softened resin composition is cured by electromagnetic radiation while being pressed against the roll 6,
The uneven shape of the roll 6 is transferred to the resin composition layer with high accuracy. As a result, the optical sheet 9 on which the uneven resin layer 8 is formed
Is obtained.

[Manufacturing Example 1] In the above apparatus example, as monomers, trimethylolpropane triacrylate (4), tetraethylene glycol diacrylate (3), butoxyethyl methacrylate (4), UA-101I manufactured by Kyoeisha Chemical Industry Co., Ltd. (Glycerin dimethacrylate isophorone diisocyanate urethane prepolymer) (6) was used. The polymer used polyethylmethacrylate (23). Polymerization initiator is Merck 2
-Methyl-2-hydroxy-phenylpropan-1-one (0.001) was used. The solvent is ethyl acetate (3
0) and methyl ethyl ketone (30) were used. As the transparent substrate, a polyethylene terephthalate film (trade name: Lumirror, manufactured by Toray) having a thickness of 188 μm, which was subjected to easy adhesion treatment, was used.

Solution casting using these, that is, the resin composition of the above composition is applied to one side of the film of this film,
The solvent component was dried to obtain a sheet-shaped laminate having a resin layer coating thickness of 70 μm. Then, an optical sheet was manufactured using the apparatus shown in FIG. That is, the heating device consumes 200
The resin composition layer is heated by using 6 far infrared heaters of W to soften the resin composition layer, and thereafter, ultraviolet rays having an integrated energy amount of 500 mJ / m ² are irradiated by using an ultraviolet lamp to cure the resin composition to give unevenness. Form a shape, total thickness 260 μm,
A lenticular lens sheet for stereoscopic photography with accurate images having a pitch of 100 μm and a groove height of 12 μm was obtained.

[Production Example 2] In the solventless method, the monomer was trimethylolpropane triacrylate (1
4), tetraethylene glycol diacrylate (1
0) and butoxyethyl methacrylate (14) were used. The polymer used was polyethylmethacrylate (62). 2-Methyl-2-hydroxy-phenylpropan-1-one (0.001) manufactured by Merck was used as a polymerization initiator. The thickness of the transparent substrate is 125μ, which has been easily treated for adhesion.
m polyethylene terephthalate film (trade name: Lumirror, manufactured by Toray) was used.

A resin composition having the above composition is applied by knife coating using these, and the coating thickness of the resin layer is 130 μm.
To obtain a sheet-shaped laminate. After that, an optical sheet was manufactured under the same conditions as in Manufacturing Example 1 using the apparatus shown in FIG. That is, six far-infrared heaters having a power consumption of 200 W are used as a heating device to heat and soften the resin composition layer, and then an ultraviolet lamp is used to obtain an integrated energy amount of 500 m.
Irradiation with ultraviolet rays of J / m ² cures the resin composition to form irregularities, total thickness 260 μm, pitch 100 μm.
Thus, a lenticular lens sheet for stereoscopic photography connecting an accurate image of m and a groove height of 12 μm was obtained.

[0025]

As demonstrated from the above, the present invention has the following effects. It is possible to manufacture a high-precision optical sheet that has no distortion in the uneven shape, has a high optical precision, and exhibits good optical characteristics. In addition, the unevenness layer is not peeled off from the transparent substrate, and a highly reliable optical sheet can be obtained.

Further, in this manufacturing method, since the flexibility of the work is high, the coating step and the molding step do not have to be continuous, and the transparent substrate having the resin composition layer can be wound and stored. Moreover, it is not necessary to use an expensive or complicated device, and the device can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in a step of forming a concavo-convex resin layer in a method for manufacturing an optical sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheet-shaped laminated body 2 Sheet-shaped transparent base material 3 Electromagnetic radiation curable resin composition 4 Heating roll 5 Pressure contact roll 6 Forming roll 7 Electromagnetic radiation irradiation device 8 Uneven resin layer 9 Optical sheet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shin Okawa, 4-1, 60 Sunadabashi, Higashi-ku, Nagoya, Aichi Prefecture, Product Development Laboratory, Mitsubishi Rayon Co., Ltd. (72) Yoshinobu Shiraishi 2-3, Kyobashi, Chuo-ku, Tokyo No. 19 Mitsubishi Rayon Co., Ltd.

Claims (1)

[Claims] 1. A non-fluidic resin composition layer comprising a thermoplastic polymer, an electromagnetic radiation curable monomer and a polymerization initiator is formed on a sheet-like transparent substrate to form a sheet-like laminate, and then the sheet-like laminate is formed. The sheet-shaped laminate is heated to soften the resin composition layer, and immediately thereafter, while the resin composition side of the laminate is pressed against a roll-shaped mold having a reverse shape of the target uneven shape on the surface. A method for producing an optical sheet, comprising forming an uneven resin layer on a transparent substrate by irradiating the resin composition layer with electromagnetic radiation through the transparent substrate to cure the resin composition layer.