JP2002086463A - Manufacturing method of lens sheet - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a replication process in the order of “cutting die → intermediate die → molding die → lens sheet” which is suitable for low cost mass production replication of lens sheets, particularly high-viscosity heat is used. Provided is a lens sheet molding die capable of preventing bubbles from being mixed in a process of applying a curable resin to an intermediate mold, having excellent dimensional accuracy, and having excellent wear resistance. A thermosetting resin is applied by screen coating to an intermediate mold molded from a mold having a reverse mold of a lens pattern, and a metal plate is applied to the intermediate mold coated with the thermosetting resin. Alternatively, the method includes a step of placing a resin plate, curing the thermosetting resin, and molding a lens sheet molding die.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lens sheet such as a Fresnel lens sheet or a lenticular sheet used for a rear projection television or the like.
The present invention relates to a method for obtaining a lens sheet itself or a molding die of the lens sheet by using a screen coating technique. The field of application of the present invention is not necessarily limited to the production of a lens sheet, and a resin is supplied to a mold surface of a molding die (a stamper having desired irregularities), and is formed of a cured product of the resin. The present invention is applied to all uses intended for manufacturing a “resin molded product having desired irregularities”.

[0002]

2. Description of the Related Art For example, for a lens sheet such as a Fresnel lens sheet or a lenticular lens sheet used for a rear projection television or the like, a hot press method and a casting method are known as methods for producing the lens sheet.

[0003] In the hot press method, a resin plate serving as a base of a lens sheet is sandwiched between a cut metal mold and a metal plate, and is heated, pressed, and cooled. In this case, the cut mold is directly used as a lens sheet molding die, and a large number of cutting dies must be prepared during mass production of the lens sheet. However, cutting dies require the cost of the original metal sheet, the length of cutting time required,
Considering the yield of cutting, etc., it is very expensive,
Considering the durability of the mold at the time of molding, many molds (=
A cutting die), which leads to an increase in manufacturing cost.

On the other hand, in the casting method, a lens sheet is manufactured by applying or injecting a melt-softened thermoplastic resin into a mold and thermally curing the resin. In this case, the manufacturing time per lens sheet is long, the efficiency of mass production of a large number of lens sheets is low, and a large number of molds are required at the same time, which also leads to an increase in manufacturing cost. There is.

In recent years, a method of molding a lens sheet using an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin has been proposed. in this way,
The ionizing radiation curable resin is applied to the end of the lens sheet mold, a transparent resin film is placed thereon, leveled by a pressure roll, cured, and released to produce a lens sheet.
According to this method, there is no problem of “durability of the mold” as in the hot press method, and there is no problem of “production time per sheet” as in the cast method. ) Is less, except for the cost of ionizing radiation-cured resins compared to thermoplastics.

[0006] In order to further reduce the manufacturing cost by eliminating the necessity of preparing a large number of cutting dies which require high manufacturing costs, recently, an intermediate die is first molded from a die (inverse of the concave and convex portions of the lens sheet) with a resin or the like. (Regular type with irregularities on the lens sheet)
A method has been proposed, in which a mold is prepared, and a mold is formed therefrom with a resin or the like, thereby producing a duplicate plate of a mold and using the duplicate as a lens sheet molding die (an inverse mold of the concave and convex portions of the lens sheet). In this case, by repeating the duplication, the number of cutting dies to be prepared can be greatly reduced as compared with the hot press method, which leads to a reduction in manufacturing cost. The problem with this method is how to produce a faithfully replicated die from the cutting die.

[0007] As for the material, first, it is desirable to use a material which can reproduce the dimensional accuracy of the original mold as it is, that is, has little shrinkage. Further, when actually forming the lens sheet, it is desirable that the number of sheets that can be formed is large and the lens sheet has excellent wear resistance. This is because if the life of the lens sheet mold duplicated from the cutting mold is long, the production cost is further reduced.

With respect to the configuration of the molding die, it is desirable that the adhesion between the molding die portion (irregularities) and its base be good.

As for the manufacturing technique, a molding technique that does not cause defects such as bubbles in the molding die (unevenness) is required. Generally, a material having a lower viscosity is often used in order to prevent air bubbles from being mixed.However, in order to produce a mold having smaller heat shrinkage before and after curing, and more excellent wear resistance after heat curing, It is inevitable to use a resin with high viscosity.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is suitable for mass production duplication of a lens sheet at low cost. In the replication process based on the order of the `` lens sheet, '' especially in the process of applying a high-viscosity thermosetting resin to the intermediate mold, it is possible to prevent air bubbles from entering, and it has excellent dimensional accuracy and excellent wear resistance It is an object of the present invention to provide a lens sheet molding die.

[0011]

According to the first aspect of the present invention, a thermosetting resin is applied by screen coating to an intermediate mold taken from a mold having a reverse mold of a lens pattern. The method includes a step of placing a metal plate or a resin plate on an intermediate mold coated with a curable resin, curing the thermosetting resin, and molding a lens sheet molding die.

As a metal plate or a resin plate used for the base of the lens sheet molding die,
It is preferable to provide a layer having high resin adhesion on the surface in consideration of the resistance during molding of the lens sheet.

Further, the thermosetting resin according to the first aspect includes:
Physical properties are required such that thermal shrinkage is smaller before and after curing, and the abrasion resistance is better after thermal curing. The viscosity of such thermosetting resins is generally high. According to the present invention, the viscosity is 100 to 50,000 mPa.
When a thermosetting resin in the range of s is used, it is suitable for preventing air bubbles from being mixed in the manufacturing process according to claim 1.

Further, the present invention is not effective as long as the “intermediate mold → molding mold” is reproduced. 5. The method according to claim 4, wherein the method of the present invention is also applied to a "molding-> lens sheet" replication process.
According to the present invention, a radiation-curable resin is applied by screen coating to a lens sheet molding die on which an inverse mold of a lens pattern is formed, and a radiation-transparent film is applied to the lens sheet molding die coated with the radiation-curable resin. Alternatively, the method includes a step of placing a sheet and curing the radiation-curable resin to form a lens sheet.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As an intermediate material referred to in the present invention, a silicon resin or the like can be used. In that case,
The silicone resin is of a curing type at room temperature, and is preferably an addition type rather than a condensation type. FIG. 1 shows an example of the manufacturing method.
Shown in According to this method, a resin pool 2 such as a silicon resin is provided in a cutting die 3, a metal plate or a resin plate is placed thereon, rolled while being pressed by a roll 4, and then left at room temperature for a predetermined period of time. Mold 5 is obtained.

As the thermosetting resin, a resin having a small shrinkage before and after thermosetting and having excellent wear resistance after thermosetting is preferable. Generally, an epoxy resin is used.

A metal plate or a resin plate is used for the base of the lens sheet molding die. If the adhesion to the thermosetting resin is poor, a layer having high resin adhesion is provided as described in claim 2. There is a need.

FIG. 2 shows a method of applying a thermosetting resin to the intermediate mold. In this step, the thermosetting resin 6 is placed on the screen 9 and moved while pressing the squeegee 10 downward, so that the thermosetting resin 6 extruded from the holes of the screen 9 is moved to the intermediate mold on the coating table 8. 5 is applied according to a general screen coating method. In some cases, fine powdered silica or the like may be added to the thermosetting resin to thoroughly prevent air bubbles from entering.

A metal plate or a resin plate is placed on an intermediate mold coated with a thermosetting resin, and thermally cured at about 65 ° C. for about 5 hours, and the intermediate mold is released. And then 150-200 ° C
And heat curing for about 10 hours to obtain a desired lens sheet mold. In FIG. 2, between a thermosetting resin layer constituting a reverse mold of the lens portion and a metal plate or a resin plate serving as a base material of a molding die, the adhesion between the two is strengthened, and when a lens molding described later is performed. Although the adhesion layer 7 is formed for the purpose of imparting printing durability, such auxiliary processing is performed as necessary.

[0020]

EXAMPLES Examples using a lens sheet mold manufactured by the method of the present invention will be described below. This example is an explanation related to an example applied to the manufacture of a Fresnel lens sheet.

As the lens material, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin is used. in this case,
Select a material that has good mold releasability from the mold during curing, has excellent lens light resistance, and has a high lens hardness. By performing vacuum degassing on these materials in advance, it is possible to avoid air bubbles during lens molding. At the base of the lens, a plate-shaped transparent resin plate made of polycarbonate or polyacrylate is used. Its thickness is suitably 10 mm or less.

FIG. 3 shows a method of manufacturing a Fresnel lens.
The ionizing radiation resin 12 is applied to the center of the Fresnel lens sheet mold 13 manufactured by the method of the present invention to form a resin pool. The resin plate 11 serving as the base of the lens sheet is placed thereon, and is pressed from above by a press machine 14 to roll the ionizing radiation resin in the circumferential direction. Thereafter, a lens sheet can be obtained by irradiating the resin plate with ionizing radiation such as ultraviolet rays or electron beams from the light source 15 to cure the ionizing radiation resin, and then releasing the resin from the mold.

The present invention is not limited to the above embodiment, but may be modified without departing from the spirit of the present invention. This method is applicable to the manufacture of lens sheets such as not only Fresnel lens sheets but also lenticular lens sheets.

The present invention may be applied to molding of a lens sheet from a lens sheet molding die.

[0025]

According to the method for manufacturing a lens sheet mold of the present invention, a lens sheet mold having no defects, good dimensional accuracy, and excellent wear resistance can be manufactured.
Rather than molding the lens directly from the mold, by duplicating a plurality of resin molds of the same dimensions from a single mold, the cost of the mold can be significantly reduced.

If the number of moldings per molding die is small, it does not lead to a significant cost reduction as a whole lens sheet molding. However, in the present invention, material selection in consideration of the wear resistance of the molding die and its The corresponding manufacturing method enabled the cost reduction of the entire lens sheet molding.

[0027]

[Brief description of the drawings]

FIG. 1 is an explanatory view conceptually showing an intermediate type manufacturing apparatus.

FIG. 2 is an explanatory view conceptually showing a step of applying a resin to an intermediate mold.

FIG. 3 is an explanatory view showing a lens sheet forming step.

[Explanation of Signs] 1: Intermediate mold substrate 2: Silicon resin 3: Cutting die 4: Pressure roll 5: Intermediate mold 6: Thermosetting resin 7: Adhesive layer 8: Coating table 9: Screen 10: Squeegee 11: Fresnel lens sheet base material 12: Ionizing radiation curable resin 13: Lens sheet mold 14: Press machine 15: Ionizing radiation source

Claims (4)

[Claims] 1. A thermosetting resin is applied by screen coating to an intermediate mold molded from a mold having an inverse mold of a lens pattern, and a metal is applied to the intermediate mold coated with the thermosetting resin. A method for manufacturing a lens sheet, comprising a step of mounting a plate or a resin plate, curing a thermosetting resin, and molding a lens sheet molding die. 2. The method according to claim 1, further comprising the step of forming a layer having high adhesion to a thermosetting resin on the surface of a metal plate or a resin plate. 3. The thermosetting resin has a viscosity of 1,000 to 50,000 mPa.
3. The method for manufacturing a lens sheet according to claim 1, wherein 4. A radiation-curable resin is applied by screen coating to a lens sheet molding die on which an inverse mold of a lens pattern is formed, and a radiation-transparent film is applied to the radiation-curable resin-coated lens sheet molding die. Alternatively, a method for manufacturing a lens sheet, comprising a step of placing a sheet, curing a radiation-curable resin, and forming a lens sheet.