JPH0692130B2 - Fresnel lens plate manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a Fresnel lens plate.

[Conventional technology]

As a method of manufacturing a Fresnel lens plate, a so-called hot pressing method of forming a Fresnel lens surface by pressing a thermoplastic resin with a heated mold, or a molten and softened thermoplastic resin composition is injected into the mold and solidified. A casting method or the like in which the Fresnel lens surface is formed by the above method is adopted.

Further, in recent years, a method of manufacturing a Fresnel lens plate has been developed in which a Fresnel lens surface is formed by using a resin such as an ultraviolet curable resin or an electron beam curable resin instead of such a thermoplastic resin. As a method of using such a resin, first, a UV-curable or electron beam-curable resin composition is applied to a mold having a Fresnel lens surface shape, and then a reinforcing substrate is pressure-laminated under reduced pressure, and then UV or electron is used. The resin composition is cured by irradiating a ray. Next, a method is adopted in which the Fresnel lens plate is obtained by releasing from the mold.

[Problems to be solved by the invention]

In the conventional method using a thermoplastic resin, the production efficiency is poor because it takes time to raise and cool the temperature. On the other hand, in the method using the ultraviolet curing type or electron beam curing type resin, the temperature change is not used, so the production efficiency is low. Has the advantage that

However, in the conventional method using the above-mentioned ultraviolet ray curable or electron beam curable resin, it is necessary to laminate the substrates under reduced pressure in order to remove bubbles in the resin composition, and continuous production is extremely difficult. It had the drawback of being

Further, in the conventional method of this type, when the Fresnel lens plate is released from the mold, it is difficult to smoothly release the substrate because the substrate having rigidity is laminated. Therefore, an opaque portion is partially formed on the Fresnel lens surface. In many cases, there were problems such as being able to do so.

In addition, since the substrate and the resin composition are in direct contact with each other during the production, swelling or crazing occurs due to the influence of the ultraviolet curable or electron beam curable resin composition depending on the type of the resin constituting the substrate. There was also the inconvenience that the selection of was extremely limited.

It is an object of the present invention to provide an excellent method for manufacturing a Fresnel lens plate, which eliminates the above-mentioned drawbacks of the prior art.

[Means for solving problems]

In order to solve the above problems, the method for producing a Fresnel lens plate of the present invention forms a resin layer by applying a resin composition of an ultraviolet curable resin or an electron beam curable resin to a mold having a Fresnel lens surface shape, After laminating a light-transmissive plastic film on the resin layer surface, the resin layer is cured by irradiating ultraviolet rays or an electron beam from the plastic film surface,
Thereafter, the cured resin layer and the plastic film are released from the mold, and then a transparent substrate is laminated on the plastic film surface to manufacture a Fresnel lens plate.

In the method of the present invention, first, an ultraviolet ray curable resin composition or an electron beam curable resin composition is applied to a mold having a Fresnel lens surface shape.

The mold can be manufactured by a conventionally known method similar to the one used in the conventional manufacturing method of this kind.

Examples of the ultraviolet curable resin composition or electron beam curable resin composition applied to the mold include ultraviolet curable resins such as urethane acrylates, epoxy acrylates, polyester acrylates, aliphatic acrylates and aromatic acrylates, or electrons. It is a resin obtained by adding a sensitizer, a monomer and the like to a line-curable resin, and these resin compositions can be applied by a method such as roll coating, flow coating or dipping.

After the application of the resin composition, the surface of the resin composition layer applied, if necessary, is smoothed to form a smooth surface.
Smoothing can be performed, for example, by a doctor blade, a mill bar, an air knife, a reverse roll, or the like.

Next, in the present invention, a light-transmissive plastic film is laminated, and then the resin layer is cured by irradiating the surface of the plastic film with an ultraviolet ray or an electron beam.

As the light-transmissive plastic film used in the present invention, a transparent film such as polyester, polycarbonate, acrylic and olefin can be used, and when these are contacted with an ultraviolet curable resin layer or an electron beam curable resin layer, they are It is possible to use one that is not attacked by the resin layer. Further, the plastic film is preferably one that can be wound to improve workability, and the thickness thereof is preferably about 12 to 300 μm.

The light-transmissive plastic film is used as a carrier for air blocking during curing of the curable resin layer, maintaining strength during release, and as a carrier for continuous production.

When laminating the light-transmissive plastic film on the resin layer, it is possible to provide the plastic film with a primer layer for improving the adhesiveness between the two.
Examples of the primer layer include polyester, vinyl chloride-vinyl acetate copolymer, urethane and the like.

In the present invention, the irradiation time or irradiation intensity of ultraviolet rays or electron beams is slightly different depending on the thickness of the resin layer, the type, etc., but in the case of ultraviolet rays, irradiation with 500 W to 3 KW of ultraviolet rays for about 10 to 30 seconds is necessary. Preferably, in the case of electron beam, 1 to 50
It is preferable to irradiate about megarad.

The resin layer and the plastic film that have been cured by being irradiated with ultraviolet rays or electron beams are then peeled off from the mold. At this time, since the plastic film is thin and flexible, it is possible to release it through a roll. In addition, the mold can be smoothly released, and an opaque portion on the Fresnel lens surface that occurs when a conventional substrate having a rigid substrate is released is not generated.

Next, in the present invention, a transparent substrate is attached to obtain a Fresnel lens plate in order to improve the mechanical strength.

The transparent substrate may be substantially transparent, and examples of the material thereof include polymethyl methacrylate, polystyrene, polycarbonate, vinyl chloride, polyolefin, polyacrylonitrile-styrene copolymer, styrene-acryl copolymer and the like.

The thickness of the transparent substrate can be appropriately selected, but in order to obtain mechanical strength, it is preferably 1 to 10 mm, preferably 2 to 4 mm. These transparent substrates can be laminated on the surface of the plastic film, for example, by adhering with an adhesive. Examples of such an adhesive include transparent materials such as urethane series, epoxy series, and acrylic series.

Further, the transparent substrate may be flat on both sides, but it is also possible to use a substrate having a lenticular lens surface or a prism surface on one surface. When such a substrate is used, a flat surface on which no lenticular lens surface or prism surface is formed is laminated on the surface of the transparent plastic film. The Fresnel lens plate obtained at this time is a lens plate having a lenticular lens surface or a prism surface on one surface.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

In FIG. 1, reference numerals 1, 1, ... Are molds having a Fresnel lens surface shape 2, and a plurality of molds 1, 1, ... Are intermittently movable by a conveyor 3. The moving mold 1 is coated with an ultraviolet curable or electron beam curable resin composition by a coating device 4 to form a resin layer 5 on the mold 1. Next, the transparent plastic film 7 which covers the surface of the resin layer 5 and the mold 1 and has the primer layer 6 formed on the surface is supplied. The film 7 is fed between the rubber rolls 8 and 8 together with the mold 1 so as to be pressed by the rolls 8 and 8. Further, since the film 7 is sequentially fed from the tip of the resin layer 5, the bubbles in the resin layer 5 are sequentially fed. When the film 7 is defoamed and the resin layer 5 is completely covered with the film 7, the resin layer 5 is in a state of containing little or no bubbles. Next is plastic film 7
Ultraviolet rays 9 or electron beams 10 are irradiated from the surface to cure the resin layer 5 and integrate it with the film 7. Next, the resin layer 5 is released from the mold 1 by making the film 7 have a predetermined angle with the roll 11. At this time, film 7
Is flexible, and the resin layer 5 has extremely fine irregularities, so that smooth release can be performed. Next, the transparent substrate 13 provided with the adhesive layer 12 is laminated on the surface of the film 7 and then cut into a predetermined shape to form a Fresnel lens plate 14 as shown in FIG.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to examples.

Example A circular Fresnel lens mold obtained by the conventional method was coated with a resin composition obtained by diluting a urethane-based UV-curable resin with an acrylic monomer by a flow coating method,
A transparent plastic film obtained by applying a polyester-based primer to an m-thick polyester film by a roll coating method was supplied to the mold surface while being pressed by a pair of rubber rolls having a diameter of 100 mm, and the film was laminated on the surface of the resin composition. At this time, the transparent plastic film is supplied by a roll so as to be wound around the surface of the resin composition at an angle of 90 °. Next, irradiate under a 1KW ultraviolet lamp for 20 seconds to cure the resin layer and integrate it with the film, then molded by injection molding.Acrylic resin substrate with lenticular lens surface on one side and flat surface on the other side. The flat surface and the film surface were bonded with a urethane adhesive to obtain a Fresnel lens plate.

Comparative Example A mold coated with a resin composition as in Example was laminated with a substrate similar to that in Example 1 under a reduced pressure of 0.1 torr by a pressing method, and then ultraviolet rays were irradiated in the same manner as in Example 1 to form a resin layer. After curing, the mold was released from the mold to obtain a Fresnel lens plate.

* The Fresnel lens plate of the comparative example was cracked in the falling ball test of 0.5 kg and 20 cm, and microcracks were generated on the wrench substrate at the cracked position. On the other hand, the Fresnel lens plate obtained in the example did not crack in the same test, and the wrench substrate did not have microcracks.

〔The invention's effect〕

As described above, the manufacturing method of the Fresnel lens plate of the present invention comprises applying a resin composition of an ultraviolet curable resin or an electron beam curable resin to a mold having a Fresnel lens surface shape to form a resin layer, After laminating a light-transmissive plastic film on the layer surface, the resin layer is cured by irradiating the surface of the plastic film with ultraviolet rays or electron beams, and then the cured resin layer and the plastic film are released from the mold, and then the plastic Since a Fresnel lens plate is produced by laminating a transparent substrate on the film surface, it is possible to degas the resin composition layer without the need for production under reduced pressure as in the conventional method, and it is also good. It has various effects such as easy mold release and a wide range of resin selection for the substrate.

[Brief description of drawings]

The drawings show the embodiments of the present invention. FIG. 1 is a process diagram for explaining an example of the manufacturing method of the present invention, and FIG. 2 is a longitudinal sectional view showing an example of a Fresnel lens plate obtained by the method of the present invention. . 1 ... Mold 2 ... Fresnel lens surface shape 5 ... Resin composition layer 7 ... Transparent plastic film 9 ... Ultraviolet ray 10 ... Electron beam 13 ... Transparent substrate 14 ... Fresnel lens plate

Claims (3)

[Claims] 1. A mold having a Fresnel lens surface shape is coated with a resin composition of an ultraviolet curable resin or an electron beam curable resin to form a resin layer, and a light-transmissive plastic film is laminated on the surface of the resin layer. After that, the resin layer is cured by irradiating it with ultraviolet rays or electron beams from the surface of the plastic film, after which the cured resin layer and the plastic film are released from the mold, and then a transparent substrate is laminated on the surface of the plastic film to Fresnel. A method of manufacturing a Fresnel lens plate, which comprises manufacturing a lens plate. 2. The method for producing a Fresnel lens plate according to claim 1, wherein the transparent substrate to be laminated is a transparent substrate having a lenticular lens surface on a surface opposite to a surface laminated with a plastic film. . 3. The method for producing a Fresnel lens plate according to claim 1, wherein the transparent substrate to be laminated is a transparent substrate having a prism surface on the surface opposite to the surface laminated with the plastic film.