JPH01192531A - Lens sheet and its manufacture - Google Patents

Abstract

PURPOSE:To prevent generation of bubbles in the lens part and a float between lens sheets, by a method wherein a lens pattern is formed of ionization radiation curing resin on a convex side surface of an ionization radiation transmission base plate in a bent form. CONSTITUTION:A matter where it is an ionization radiation transmission and transparent body and bending processing of a radius of curvature of about 1000-10000mm has been performed beforehand is used for a base plate 1. With this construction, the base plate 1 is apt to defoam at the time of molding and in the case where the same is used for a transmission screen by combining the same with the other lens sheet, float between the sheets can de prevented. Ultraviolet curing resin or electron curing resin is used as ionization radiation curing resin constituting a lens part 2. A resin rich area of the ionization radiation curing resin is formed on an end part of a molding tool, to begin with, a bubble entering into a space between the base plate 1 and the molding tool is extruded and adhesion is held. Then the base plate is laminated to the foregoing ionization radiation curing resin while levelling the ionization radiation curing resin with a pressurizing roll through the base plate. Then the same is cured by applying the ionization radiation to the same.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to a lens sheet such as a Fresnel lens sheet, a prism lens sheet, a lenticular lens sheet, etc. used in a transmission type screen, and a method for manufacturing the same. The present invention relates to a curved lens sheet molded from a layer or two layers of ionizing radiation-cured resin, and a method for manufacturing the same.

[Prior art]

Conventionally, this type of lens sheet has been molded by a pressing method, a casting method, or the like. The former press method has poor productivity because it involves a heating, pressurizing, and cooling cycle. In addition, the latter casting method requires a lot of time to produce because the monomer is poured into a mold and polymerized, and a large number of molds are required, resulting in an increase in manufacturing costs.

In order to solve this problem, an ionizing radiation curing resin such as an ultraviolet curable resin or an electron beam curing resin is poured between the mold and the base plate, and ionizing radiation such as ultraviolet rays or an electron beam is irradiated. Various ionizing radiation curing resin methods (photopolymer methods) have been proposed in which the resin is cured and polymerized.

For example, in JP-A No. 62-33613 ``Method for manufacturing a screen for a video projector,'' [a UV-curable resin is injected into a lens mold under normal pressure and covered with a UV-transparent plate. A proposal has been made which aims to cure the UV-curable resin by irradiating the UV-curable resin filled between the mold and the UV-curable resin through the UV-transparent plate, and then release the cured UV-curable resin from the mold. ing.

(Problems to be solved) The method proposed above had the following problems to be solved.

First, as a means of laminating an ultraviolet-transparent substrate on the ultraviolet-curable resin injected into the mold, a vacuum pin was used to laminate the ultraviolet-transparent substrate on one side of the mold in which the ultraviolet-curable resin was injected. It is proposed that the other side be covered with ultraviolet curable resin to avoid trapping air bubbles. In this case, the control device and drive device become complicated, leading to an increase in cost, and it is impossible to completely cover the air bubble-free.

Second, if bubbles are mixed into the resin during injection, it is proposed to remove them using a pipette, etc., but detecting the presence of bubbles and removing them manually is not productive. Bad and uncertain.

Thirdly, the resin must be defoamed before injection, which requires equipment and time, leading to poor productivity and increased costs.

If such bubbles remain in the lens part, partial defects will occur.
Lens quality will deteriorate.

On the other hand, when multiple such lens sheets are combined and used as a transmission screen, each lens sheet deforms due to distortion of the lens sheet that occurs during manufacturing and environmental changes in temperature and humidity, resulting in the lens sheets not being in close contact initially. Even if
Gaps could then form between the sheets. For this reason, there were other problems in that not only the appearance but also the optical characteristics as a transmission screen were deteriorated, such as a decrease in resolution and the occurrence of color unevenness.

An object of the present invention is to provide a lens sheet that does not contain air bubbles in the lens portion, and a method for manufacturing the same.

Another object of the present invention is to provide a lens sheet that does not cause floating between lens sheets even when a plurality of lens sheets are used in combination, and a method for manufacturing the same.

[Disclosure of the Invention] As a result of various studies, the inventor of the present invention discovered that when applying an ionizing radiation-curable resin to a mold, the above-mentioned degassing can be achieved by stacking and degassing the curved base plate while leveling it with rollers. We have discovered that the object can be achieved and have come up with the present invention.

FIG. 1 is a diagram showing a lens sheet having a first configuration according to the present invention, and FIG. 2 is a flowchart for explaining a method for manufacturing the lens sheet having the first configuration.

That is, the lens sheet of the first configuration according to the present invention is
It is comprised of a curved base plate 1 that is transparent to ionizing radiation, and a lens portion 2 in which a lens pattern is formed with an ionizing radiation-curable resin on the convex surface of the base plate.

The base plate 1 may be any transparent material that serves as a support for the lens portion and constitutes a part of the lens sheet and is transparent to ionizing radiation, and may be an acrylic plate, a polycarbonate plate, or the like. This base plate 1 may be one that has been bent in advance to have a radius of curvature of approximately 1,000 to 10,000 mm.

The reason why the base plate 1 is curved in advance is that it is easy to degas during molding, as will be described later, and because the lens sheet molded using such a base plate is curved, it is difficult to combine it with other lens sheets. This is because when the sheet is used for a transmission type screen or the like, floating between the sheets can be prevented. Also, since there is no need to warp the material afterwards,
The manufacturing process can be simplified.

The base plate 1 may be provided with a primer layer of vinyl chloride/vinyl acetate copolymer, urethane, or the like for improving adhesion.

The lens portion 2 can have a lens shape such as a Fresnel lens, a prism lens, or a lenticular lens.

The ionizing radiation curing resin that makes up this lens part is as follows:
Ultraviolet curable resins or electron beam curable resins can be used, for example, urethane acrylate, epoxy acrylate 5, polyester acrylate, polyether acrylate, melamine acrylate and other polymerizable oligomers and monomers having an acryloyl group, acrylic acid, acrylamide, acrylonitrile, A polymerizable oligomer or monomer having a polymerizable vinyl group such as styrene may be used alone or in combination, with additives such as a sensitizer added if necessary.

In order to improve general mechanical properties such as surface strength and hardness, it is better to use monomers or prepolymers with polyfunctional groups as the ionizing radiation-curable resin that constitutes such lens parts. More than one group is preferably used.

In the past, the ionizing radiation curing resin was selected in consideration of the processing temperature in the warping process to prevent the lens sheet from lifting after molding, but this is not necessary in the present invention.

Further, the ionizing radiation-cured resin may contain a diffusing agent. Diffusing agents can improve coating suitability and prevent polymerization shrinkage, and
Diffusibility can be imparted. As the diffusing agent, glass, silica, alumina, insoluble plastic, talc, etc. can be used.

Next, as shown in FIG. 2, the first lens sheet manufacturing method includes a resin coating step 101, a leveling and laminating step 102, a resin curing step 103, and a mold release step 104. .

The resin coating step 101 is a step of forming a resin pool of ionizing radiation-cured resin at the end of the mold in which the lens pattern mold is formed. In this process, the ionizing radiation-cured resin functions to push out air bubbles that may have entered between the curved base plate to be laminated and the mold, and to provide adhesiveness to the base plate. As a method for forming the resin pool of the ionizing radiation-cured resin, methods such as a squeezing method, a flow coating method, and a roll coating method can be used.

In the leveling and laminating step 102, the convex side of a curved base plate transparent to ionizing radiation is placed on the resin pool of the ionizing radiation-cured resin, and the ionizing radiation-cured resin is leveled with a pressure roll through the base plate. This is a step of laminating a base plate on the ionizing radiation-cured resin. In this process, transparent base plates curved into an arc are stacked so that only the end of the pressure roll is in contact with the mold, and pressure is applied from above the base plate and from below the mold with the pressure roll. By laminating, it works to push out air bubbles that get into the resin and between the valleys of the lens pattern of the mold, and to make the thickness of the molded product uniform.

When laminating in this way, if the base plate is flat, the end of the base plate on the opposite side of the pressure roll should be raised by external force to prevent air bubbles from entering when laminating the ionizing radiation-cured resin. If the base plate is curved in an arcuate shape in advance as in the present invention, there is no need to apply the external force during molding, and the manufacturing equipment becomes simpler.

The resin curing step 103 is a step of irradiating the ionizing radiation-cured resin with ionizing radiation and curing it.

In this step, the ionizing radiation curing resin is cured by irradiating it with ionizing radiation. At this time, it is preferable to bring the light source as close as possible to the roll pressurizing part.
This is to prevent lifting between the mold and the base plate and to prevent air bubbles from re-entering between them.

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

Next, a second lens sheet and a method for manufacturing the same according to the present invention will be explained.

FIG. 3 is a diagram showing a lens sheet having a second configuration according to the present invention, and FIG. 4 is a flowchart for explaining a method for manufacturing the lens sheet having the second configuration.

In other words, the lens sheet having the second configuration according to the present invention includes a curved base plate 1 that is transparent to ionizing radiation, and a first ionizing radiation-curable resin 21 on the convex surface of the base plate at the tip of the lens pattern. It is composed of a lens portion in which the vicinity thereof is molded and the base side of the lens pattern is molded with a second ionizing radiation curable resin 22.

In the lens sheet of the second configuration, as shown in an enlarged view in FIG. 3B, the lens portion is composed of two layers: a first ionizing radiation-cured resin 21 and a second ionizing radiation-cured resin 22. Since the other components are substantially the same as the lens sheet of the first configuration, only the differences will be explained.

As the ionizing radiation curable resin, the same ones as those mentioned above can be used, but the physical properties of the first ionizing radiation curable resin include mold transferability, defoaming property, wettability to the mold 1
Emphasis is placed on surface hardening, and for the second ionizing radiation-cured resin, adhesion to the base plate and fluidity are important.

In addition, the viscosity of the first ionizing radiation-cured resin is 2
A low viscosity adjusted to 0.00 centivoise or less is preferable, and the second ionizing radiation curing resin has a viscosity of 500 to 5000 centivoise.
A relatively high viscosity adjusted to centipoise is used. The reason for this is that the viscosity of the first ionizing radiation-cured resin must be low because it is applied to the entire surface of the mold so as not to contain air bubbles between it and the fine lens pattern of the mold, and the second ionizing radiation-cured resin This is because the viscosity must be high to some extent because the resin is applied while leveling to drive out air bubbles within the resin. By forming the first ionizing radiation-cured resin layer in this way, the defoaming property at the mold interface is further improved.

In this way, by using two layers of resin, each part of the mold, base plate, or molded lens sheet itself can more effectively perform its respective functions, and these functions can also be combined into two layers. By separating, you can widen the range of resin selection.

The selection conditions for each ionizing radiation curable resin will be further explained below. In the case of a lens sheet, it is required that the refractive indexes of both sheets are at least approximately equal. This is because the interface where the first ionizing radiation curing resin and the second ionizing radiation curing resin are laminated is not necessarily flat.
This is because if the refractive indexes of the two resins differ greatly, uniform light cannot be obtained.

If this relationship is satisfied, the first ionizing radiation curing resin and the second
The ionizing radiation-cured resins may be made of the same material or different materials, and in the case of different resins, combinations with approximately the same refractive index are used, taking into account physical properties. For example, a urethane acrylate resin with good mold reproducibility can be used as the first ionizing radiation curing resin, and an epoxy acrylate resin with good adhesion to the base film can be used as the second ionizing radiation curing resin. . In addition, changing the resin temperature in the processing process of the first ionizing radiation curing resin and the second ionizing radiation curing resin, adding additives (antifoaming agent, leveling agent, etc.),
Wettability to the mold is improved by adding a solvent or the like, or by changing the blending ratio of monomers, oligomers, etc. of the first ionizing radiation-curable resin and the second ionizing radiation-curable resin.

Fluidity, viscosity, etc. may be appropriately adjusted.

Furthermore, both or one of the first ionizing radiation-curable resin and the second ionizing radiation-curable resin can include a diffusion side as described above.

Next, the method for manufacturing a lens sheet having the second configuration according to the present invention includes a first resin coating step 201 as shown in FIG.
, a second resin coating step 202 , and a leveling and laminating step 203
, a resin curing process 204 , and a mold release process 205 .

The first resin application step 201 is a step of applying a first ionizing radiation-curable resin to the entire surface of the mold in which the lens pattern is formed. This step is a step for uniformizing the wettability of the mold, stabilizing the amount of coating, and promoting defoaming in the next step. Specifically, the roll coating method.

This can be carried out by a silk screen method, a curtain method, a gravure method, or the like.

A second resin coating step 202 includes applying a second resin to the end of the mold.
This is a step of forming a resin reservoir of Tin radiation-cured resin.

In the leveling and laminating step 203, the convex side of a curved base plate transparent to ionizing radiation is placed on the resin pool of the second ionizing radiation-cured resin, and the second layer is laminated with a pressure roll through the base plate.
This is a step of laminating the base plate on the second ionizing radiation-cured resin while leveling the ionizing radiation-cured resin.

The resin curing step 204 is a step of curing each of the ionizing radiation-cured resins by irradiating them with ionizing radiation.

The mold release step 205 is a step of releasing each of the ionizing radiation-cured resins from the mold.

Each of the steps 202 to 205 can be performed in substantially the same manner as the steps (101 to 104) of the method for manufacturing a lens sheet having the first configuration.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

FIG. 5 is a process diagram showing an example of a lens sheet having a first configuration and a manufacturing method thereof according to the present invention.

In FIG. 5, ``■'' is a base plate, 2 is an ionizing radiation curing resin, 3 is a mold, 4 is a roll, and 5 is a U■ light source.

First, as shown in Fig. 5(a), the left end (
The ionizing radiation curing resin 2 was dropped onto the roll 4 side) by a flow coating method to form a resin pool of 1.0 g/c. This ionizing radiation curing resin 2 has a refractive index of 1.4.
9. An epoxy acrylate-based ultraviolet curing resin whose viscosity was adjusted to 1500 centivoise was used.

Furthermore, as shown in FIG. 5(b), as a bent transparent base plate 1, a UV-transparent thick plate 3 coated with a vinyl chloride/vinyl acetate copolymer primer is used.
．． 0 mm acrylic plates bent to a radius of curvature R of 6000 mm were loaded, as shown in Figure 5 (C).
Pressure was applied by rolling a pressure roll 4.4 at a speed of 50 cm/min. At this time, air bubbles that enter between the mold 3 and the base plate 1 are pushed out at a portion indicated by A in the figure.

At this time, using the UV light source 5 from the base plate 1 side,
The ionizing radiation curing resin 2 was cured by irradiation with ultraviolet light (UV) at W/cm.

Finally, as shown in FIG. 5(d), the mold 3 was depressurized and released to obtain an arched Fresnel lens sheet.

In this Fresnel lens sheet, the lens part 2 is made of ionizing radiation-cured resin, and the base plate 1 is laminated.The lens part does not contain air bubbles and is a Fresnel lens that forms a transmission screen. When used as a sheet, good adhesion was obtained when used in combination with a lenticular lens sheet of the same size (thickness: 1.25 mm).

FIG. 6 is a process diagram showing an example of a lens sheet having a second configuration and a method for manufacturing the same according to the present invention.

In FIG. 6, 21 is a first ionizing radiation curing resin, 22 is a second ionizing radiation curing resin, and the same reference numerals are given to parts that perform the same functions as in the previous embodiment. .

First, as shown in FIG. 6(a), a first mold
The ionizing radiation curing resin 21 has a refractive index of 1.49. A urethane acrylate type U cured resin adjusted to a viscosity of 100 centipoise is made to a thickness of 5 cm using the silk screen method.
It was applied to a thickness of 0 μm. Next, the second ionizing radiation-curable resin 22 was dropped onto the left end (roll 4 side) of the mold 3 by a flow coating method to form a resin pool of ], Og/cd. The second ionizing radiation curing resin 22 has a refractive index of 1.
49. An epoxy acrylate-based ultraviolet curing resin whose viscosity was adjusted to 1500 centivoise was used.

Furthermore, as shown in FIG. 6 (bl), as a bent transparent base plate 1, a UV-transparent thickness 3 coated with a vinyl chloride/vinyl acetate copolymer primer is used.
．． 0mm acrylic plate, radius of curvature R is 6000rr1m
The bent pieces were loaded, and as shown in FIG. 6(C), pressure was applied by rolling the pressure rolls 4, 4 at a speed of 50 cm/min. At this time, at the part indicated by A in the figure, the mold 3
Air bubbles that enter between the base plate 1 and the base plate 1 are pushed out.

At this time, using the UV light source 5 from the base plate 1 side,
The first ionizing radiation curing resin 21 and the second ionizing radiation curing resin 22 were cured by irradiation with ultraviolet rays (UV) at W/cm.

Finally, as shown in FIG. 6(d), the mold 3 was released and released to obtain an arched Fresnel lens sheet.

In this Fresnel lens sheet, the vicinity of the tip of the lens part 2 is molded with a first ionizing radiation curing resin 21, the base side of the lens part 2 is molded with a second ionizing radiation curing resin 22, and the base plate 1 is laminated. The lens part, especially the surface, does not contain any air bubbles, and when used as a Fresnel lens sheet constituting a transmission screen, it can be used as a lenticular lens sheet of the same size (plate [1
As a result of using it in combination with ゜25 mm), good adhesion was obtained.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the base plate is sandwiched between the ionizing radiation-cured resin applied to the mold, and air bubbles are removed by leveling it with a pressure roll, so that the molded Air bubbles no longer get mixed into the lens part of the lens sheet.

In addition, we divided the ionizing radiation-cured resin into two layers and coated the entire surface of the mold with good wettability in advance to prevent air bubbles from entering between the resin and the fine pattern of the mold. The mold reproducibility has improved.

Furthermore, since the base plate was used in a curved manner, it became easier to defoam when leveling with a pressure roll.

Furthermore, as a result of using a curved base plate, a curved lens sheet can be manufactured, which improves the adhesion between the lens sheets when used in combination with other lens sheets as a transmission screen. Ta.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a lens sheet having a first configuration according to the present invention, and FIG. 2 is a flowchart for explaining a method for manufacturing the lens sheet having the first configuration. FIG. 3 is a diagram showing a lens sheet having a second configuration according to the present invention, and FIG. 4 is a flowchart for explaining a method for manufacturing the lens sheet having the second configuration. FIG. 5 is a process diagram showing an example of a lens sheet having a first configuration and a manufacturing method thereof according to the present invention. FIG. 6 is a process diagram showing an example of a lens sheet having a second configuration and a method for manufacturing the same according to the present invention. ■ ... Hess Mutan 2 ... Ionizing radiation curing resin 21 ... First ionizing radiation curing resin 22 ... Second ionizing radiation curing resin 3 ... Molding mold 4 ... Pressure roll 5... UV light source patent applicant Dainippon Printing Co., Ltd. Agent Patent attorney Kama 1) Second son Po Ka-ku, \Op 0''. Procedural amendment 2, title of invention Lens sheet and method for manufacturing the same Representative Yoshi Kitajima Shun 4, Agent address: 36-3-6, Higashiikebukuro-chome, Toshima-ku, Tokyo 170 Kumo, Number of claims increased by amendment None 7, Subject of amendment Detailed explanation of the invention in the specification column 8, Amendment Contents: As shown in the attached document, the details of the amendment are as follows: […adjust it] on page 15, line 8 of the specification.
Correct as follows. ...You just need to adjust it. When adjusting with a solvent, it is desirable to allow the solvent to run out after coating in order to prevent resin shrinkage and solvent deterioration. "that's all

Claims (4)

[Claims] (1) a curved base plate transparent to ionizing radiation;
and a lens portion having a lens pattern formed with an ionizing radiation-curable resin on the convex surface of the base plate. (2) A resin coating step of forming a resin pool of ionizing radiation curing resin at the end of the mold where the lens pattern mold is formed, and a convexity of a curved base plate transparent to ionizing radiation in the resin pool of the ionizing radiation curing resin. a leveling and laminating step of laminating the base plate onto the ionizing radiation curable resin while leveling the ionizing radiation curable resin with a pressure roll through the base plate; and irradiating the ionizing radiation curable resin with ionizing radiation. A method for manufacturing a lens sheet comprising: a resin curing step of curing the resin by curing the resin, and a mold release step of releasing the ionizing radiation-cured resin from the mold. (3) a curved base plate transparent to ionizing radiation;
A lens sheet comprising: a lens portion formed by molding the tip portion of the lens pattern with a first ionizing radiation curing resin and molding the base side of the lens pattern with a second ionizing radiation curing resin on the convex side surface of the base plate. (4) A first resin coating step of applying a first ionizing radiation curing resin to the entire surface of the mold in which the lens pattern mold is formed, and a resin pool of the second ionizing radiation curing resin at the end of the mold. a second resin coating step of forming a second ionizing radiation-cured resin, and placing the convex side of a curved base plate transparent to ionizing radiation on the resin puddle of the second ionizing radiation-cured resin and applying a pressure roll to the second resin through the base plate; a leveling and laminating step of laminating the base plate on the second ionizing radiation-curable resin while leveling the ionizing radiation-curable resin; a resin curing step of curing each of the ionizing radiation-curable resins by irradiating them with ionizing radiation; A method for manufacturing a lens sheet, comprising a mold release step of releasing each of the ionizing radiation-cured resins from the mold.