JP2623279B2 - Resin coating method in lens sheet manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to molding a lens sheet such as a Fresnel lens sheet, a prism lens sheet, a lenticular lens sheet, etc. used for a transmission screen using an ionizing radiation-curable resin. Regarding a method for manufacturing a lens sheet,
In particular, it relates to an improvement in a resin coating method for applying the ionizing radiation-curable resin.

(Background technology)

As a method for forming this kind of lens sheet, an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin is poured between the mold and a base member of a mold and irradiated with ionizing radiation such as an ultraviolet ray or an electron beam. Has been proposed, an ionizing radiation curable resin method (photopolymer method) in which the resin is cured and polymerized.

However, this ionizing radiation curable resin method has a problem that unless a manufacturing operation is performed in a vacuum atmosphere, bubbles are mixed in or on the surface of the lens sheet, and the quality of the molded lens sheet is deteriorated. Was.

In order to solve such a problem, the applicant has
The following methods are proposed.

4 to 6 are views for explaining a method of manufacturing a lens sheet proposed by the present applicant.

As shown in FIG. 4A, the method of manufacturing the lens sheet basically includes a resin coating step 101 and a leveling and laminating step 102.
, A resin curing step 103 and a release step 104.

The resin application step 101 is a step of forming a resin pool of the ionizing radiation-curable resin on the mold on which the lens pattern mold is formed. The ionizing radiation curing resin in this step is
It extrudes air bubbles that enter between the base member to be laminated and the molding die, and also functions to provide adhesion to the base member. Methods for forming a resin pool of ionizing radiation-curable resin include a squeezing method, a flow coating method,
Methods such as a roll coating method and a quantitative separation method can be used.

The leveling and laminating step 102 is a step in which an ionizing radiation-curable resin is accumulated in a resin pool of the ionizing radiation-curable resin, and the ionizing radiation-curable resin is laminated with a pressure roll. This step serves to extrude air bubbles between the mold and the base member and to make the thickness of the molded product uniform.

The base member used here is only required to be transparent to ionizing radiation, and may be a thick plastic plate or a relatively thin film. In the case where the thickness is thick, it may be flat or curved. further,
This base member may be peeled off last. The base member may be coated with a vinyl chloride / vinyl acetate copolymer-based or urethane-based primer in order to improve the adhesiveness, or may be coated with a release agent when peeled off later.

The resin curing step 103 is a step of irradiating the ionizing radiation-curable resin with ionizing radiation to cure the resin. In this step, the ionizing radiation-curable resin is cured by irradiating ionizing radiation such as ultraviolet rays or electron beams. At this time, it is preferable that the light source be as close as possible to the roll pressing unit. This is to prevent floating between the mold and the base member, and to prevent air bubbles from entering between them.

The release step 104 is a step of releasing the ionizing radiation-curable resin from the mold.

As another method, as shown in FIG.
, A resin application step 201, a second resin application step 202, a leveling lamination step 203, a resin curing step 204, and a release step 205.

Here, the added first resin applying step 201 is a step of applying the first ionizing radiation curable resin to the entire surface of the mold on which the lens pattern mold is formed. This step is to make the wettability of the mold uniform and to promote defoaming in the next step. Specifically, it can be carried out by a roll coating method, a silk screen method, a curtain method, a gravure method, a squeezing method, or the like.

The next steps (202 to 205) are the same as the aforementioned steps (101 to 10).
It can be performed in substantially the same manner as 4).

In any of the above methods, when forming a resin pool of the ionizing radiation-curable resin (101, 202), the following procedure was performed. Here, the method of FIG. 4B will be described as an example.

First, the first ionizing radiation-curable resin 1 is applied to the entire surface of the mold 4, and the second ionizing radiation-curable resin 2 is linearly applied to one end of the mold 4 as shown in FIG. A resin puddle was formed.

Thereafter, as shown in FIG.
The base member 3 was placed thereon, and the layers were laminated while being leveled by the pressure rolls 5,5.

Thus, when defoaming using a pressure roll,
As for the width of the base member 3, the forming die 4, and the pressing roll 5, as shown in FIG. 6B, the width of the pressing roll 5 <the forming die 4 <the base member 3 is preferably used.

The reason is that the forming die 4 <the pressure roll 5 <the base member 3
In this case, the deformation of the base member 3 may return after the pressurization, and bubbles may enter from the end face. In fact, mold 4
The base member 3 (in the case of an acrylic plate), which has been warped and twisted by about 0.5 to 1.0 mm itself, deforms at the time of pressurization and returns at the time of decompression, and tunneling occurs. In the case of the base member 3 <the pressure roll 5 <the molding die 4, the resin overflows from the end of the base member 3, and the resin remains on the molding die 4 after curing, and the molding die becomes dirty. In order to avoid these problems, the width relationship shown in FIG. 6B was adopted.

〔Problems to be solved〕

In this way, when the second ionizing radiation-curable resin 2 is leveled using the apparatus having the width relationship, the 6C
As shown in the figure, the amount of accumulated resin at the right corner of the molding die 4 is reduced, resin is cut off in an area indicated by A on the end surface of the molding die 4, and dirt remains on the molding die 4 after releasing. There was a problem.

In addition, the second ionizing radiation-curable resin 2 is
When leveling by 5, unevenness occurred in the application in the area indicated by B in FIG. 6C, and there was a possibility that air bubbles might enter the area.

An object of the present invention is to solve the above-described problems and to prevent resin breakage at an end of a molding die, and to provide a resin coating method in a lens sheet manufacturing method capable of reliably molding a peripheral portion of a lens sheet. To provide.

[Disclosure of the Invention]

As a result of various studies, the present inventors have found that the above object can be achieved by forming a resin pool of ionizing radiation-curable resin on both sides of a mold, and have accomplished the present invention.

That is, in the resin coating method in the method for manufacturing a lens sheet according to the present invention, a resin pool of an ionizing radiation-curable resin is formed on a mold on which a lens pattern is formed, and a base member is superimposed on the resin pool and uniformly pressed by a pressure roll. In the method of manufacturing a lens sheet that is laminated while being irradiated with ionizing radiation, cured and then released, the resin pool of the ionizing radiation-curable resin is formed by pressing a roll end of the molding die and a shaft of the roll. It is configured to be applied to both ends in a direction substantially orthogonal.

Here, as the ionizing radiation curable resin, an ultraviolet curable resin or an electron curable resin can be used. For example, a polymerizable oligomer having an acryloyl group such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, and melamine acrylate; Monomer and monomer or polymerizable oligomer or monomer having polymerizable vinyl group such as acrylic acid, acrylamide, acrylonitrile, styrene, etc.
If necessary, an additive such as a sensitizer may be used.

As the ionizing radiation-curable resin constituting such a lens sheet, it is better to use a monomer or prepolymer having a polyfunctional group in order to increase general mechanical properties such as surface strength and hardness, and in fact, it is preferable to use a bifunctional monomer. More than groups are preferably used.

The ionizing radiation-curable resin may contain a diffusing agent. The diffusing agent can improve the suitability for coating, prevent condensation shrinkage, and impart diffusivity. As a diffusing agent,
Glass, silica, alumina, insoluble plastic, talc and the like can be used.

When applying an ionizing radiation curable resin to two layers, the first
As the physical properties of ionizing radiation-curable resin, emphasis is placed on mold transfer, defoaming, wettability to mold, and surface curability.
As the second ionizing radiation-curable resin, importance is attached to adhesiveness with the base member, peelability, and fluidity.

As the viscosity, the first ionizing radiation curable resin is:
A low-viscosity resin adjusted to 200 centipoise or less is preferable, and a relatively high-viscosity resin adjusted to 500 to 5000 centipoise is used as the second ionizing radiation-curable resin. The reason for this is that the first ionizing radiation curable resin must be low in viscosity because it is applied to the entire surface so as not to contain bubbles between the fine ionizing radiation curable resin and the fine lens pattern of the mold. The reason for this is that the viscosity must be high to some extent because the air bubbles in the resin are expelled by uniform application. By forming the first ionizing radiation-curable resin layer in this manner, the defoaming property at the mold interface is further improved.

Thus, by forming the resin into two layers, the molding die,
Each function for each part of the base member or the molded lens sheet itself can be more effectively performed, and by dividing those functions into two layers, the range of resin selection can be widened.

Hereinafter, conditions for selecting each ionizing radiation-curable resin will be further described. In the case of a lens sheet, it is required that at least the two have substantially the same refractive index. This is because the interface at which the first ionizing radiation-curable resin and the second ionizing radiation-curable resin are laminated is not always flat,
If the refractive indexes of the two resins are significantly different, uniform light cannot be obtained.

If this relationship is satisfied, the first ionizing radiation curable resin and the second ionizing radiation curable resin may be the same material or different materials. In the case of different resins, a combination of substantially equal refractive indices may be used in consideration of the physical properties. For example, a urethane acrylate resin having good mold reproducibility is used as the first ionizing radiation curing resin, An epoxy acrylate resin having good adhesion to the base member can be used as the ionizing radiation curing resin. In addition, the first ionizing radiation curing resin and the second
Changing the resin temperature in the process of processing the ionizing radiation-curable resin, adding additives (such as an antifoaming agent or a leveling agent), a solvent, or the like, or combining the first ionizing radiation-curable resin with the second ionizing radiation. The wettability, fluidity, viscosity, and the like of the molding die may be appropriately adjusted by changing the mixing ratio of the monomer, oligomer, and the like of the cured resin. When the adjustment is performed using a solvent, it is desirable to volatilize the solvent after coating in order to prevent resin shrinkage and solvent deterioration.

Further, both or one of the first ionizing radiation-curable resin and the second ionizing radiation-curable resin may contain a diffusing agent.

In the resin coating method according to the present invention, the resin pool may be formed on the roll-side end of the forming die and on both sides substantially perpendicular to the axis of the roll, and the roll-side end and the resin pool on both sides are continuous. Or discontinuously.

Further, as the coating device, a device in which a fixed amount coating device such as a dispenser and an XY stage are combined can be used. The dispenser is a resin tank containing an ionizing radiation-curable resin, a fixed-quantity pump such as a gear pump or a snake pump for quantitatively separating the resin in the resin tank, and the resin provided with an electromagnetic valve or the like for preventing resin dripping. And an ejection nozzle for ejecting the ink. The application is performed while moving the ejection nozzle to the application shape according to the present invention on the XY stage under program control.

The amount of the resin of both sizes is determined by the dimensions of the molding die, the base member, the pressure roll and the like for the purpose of preventing the resin from running out. For example, mold width 600mm, base member width 63
When the pressure roll width is 500 mm and the pressure roll width is 500 mm, the resin pool on the roll side end is 60 to 120 g, and the resin pool on both sides is 15 to
It can be suitably carried out in the range of 30 g.

In the present invention, a method for manufacturing a lens sheet such as a Fresnel lens, a prism lens, and a lenticular lens has been described. However, this method is applicable to manufacturing a lens having a fine pattern on its surface, such as an optical card, an optical disk, and a hologram. Can also be applied.

〔Example〕

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

1 and 2 are views showing an embodiment of a resin coating method in a method for manufacturing a lens sheet according to the present invention.

In this embodiment, the case of two coatings will be described as an example. In each figure, 1 is a first ionizing radiation curing resin, 2 is a second ionizing radiation curing resin, 3 is a base member, 4 is a molding die, 5
Is a pressure roll, and 6 is a UV light source.

First, as a first ionizing radiation-curable resin 1, a urethane acrylate UV curable resin adjusted to a refractive index of 1.49 and a viscosity of 50 centipoise is formed on the entire surface of a mold 4 having a Fresnel lens mold having a length of 1 m and a pitch of 0.1 mm. The resin was applied to a thickness of 50 μm by a squeezing method.

Next, a molding die 4 is formed by a dispenser having a discharge nozzle attached to an XY stage controlled by a program.
Then, a resin pool of the second ionizing radiation-curable resin 2 as shown in FIG. 1 was formed. As for the resin pool, 100 g of the resin pool 2A on the left end (roll 5 side) and 20 g on each side
Resin pools 2B and 2C were formed for each g.

The second ionizing radiation-curable resin 2 has a refractive index of 1.
A urethane acrylate-based UV-curable resin adjusted to a viscosity of 2,000 centipoise was used.

After forming the resin reservoir in this manner, as shown in FIG. 2A, a 3.0 mm thick transparent acrylic plate having a thickness of 3.0 mm coated with a vinyl chloride / vinyl acetate copolymer-based primer was used as the base member 3. Were laminated, and the pressure rolls 5, 5 were rolled at a speed of 10 cm / min and pressed. At this time, bubbles entering between the mold 4 and the base member 3 are extruded at a portion indicated by A in the drawing. At this time, the UV light source 6
The first ionizing radiation-curable resin 1 and the second ionizing radiation-curing resin 2 were cured by irradiating with 160 W / cm ultraviolet (UV). Finally, the mold 4 was depressurized and released to obtain a 3.2 mm thick Fresnel lens sheet as a lens sheet.

According to this coating method, no resin breakage occurred at both right corners of the mold 4.

In addition, no bubbles were mixed in the periphery of the molded lens sheet, and the lens shape was sharply finished.

FIG. 3 is a view showing another embodiment of the resin coating method in the lens sheet manufacturing method according to the present invention.

As shown in FIG. 3, the production was carried out under the same conditions as in the above embodiment, except that the resin pools 2E and 2F on both sides were formed apart from the resin pool 2D at the roll side end. As a result, the first
A lens sheet similar to that of the example was obtained.

〔The invention's effect〕

As described above in detail, according to the present invention, since the resin pool of the ionizing radiation-curable resin is applied to both sides of the mold, the resin is not cut off at the end of the mold. In addition, molding defects at the periphery of the molded lens sheet were eliminated.

[Brief description of the drawings]

1 and 2 are views showing an embodiment of a resin coating method in a method for manufacturing a lens sheet according to the present invention. FIG. 3 is a view showing another embodiment of the resin coating method in the lens sheet manufacturing method according to the present invention. 4 to 6 are views for explaining a method of manufacturing a lens sheet proposed by the present applicant. DESCRIPTION OF SYMBOLS 1 ... 1st ionizing radiation curing resin 2 ... 2nd ionizing radiation curing resin 3 ... Base plate 4, ... Mold 5 ... Pressure roll, 6 ... UV light source

Claims (1)

(57) [Claims] 1. A resin reservoir of an ionizing radiation-curable resin is formed in a mold on which a lens pattern is formed, and a base member is superimposed on the resin reservoir and laminated while being leveled by a pressure roll.
In the method for manufacturing a lens sheet to be released after being irradiated with ionizing radiation and cured, the resin pool of the ionizing radiation-curable resin is formed in a direction substantially perpendicular to an axis of the pressing roll side end of the molding die and the roll. A resin coating method in a method for producing a lens sheet, wherein the resin coating method is applied to both ends.