JPH01192530A - Manufacturing method of lens sheet - Google Patents

Abstract

PURPOSE:To obtain a lens sheet which has no bubble in a lens part and is superior in optical characteristics, by a method wherein a lens pattern is molded of ionization radiation curing resin into a thin sheet-like state. CONSTITUTION:A simple substance or a compounded matter such as polymerizable oligomer having an acryloyl group or the polymerizable, oligomer having a monomer and polymerizable vinyl group or a monomer is used for ionization radiation curing resin 1. As a base plate is eliminated from a lens sheet, a matter having appropriate flexibility, mechanical strength and high transparency is used for the ionization radiation curing resin. A resin rich area of the ionization radiation curing resin is formed on an end part of a molding tool at a resin coating process 101 and an ionization radiation transmission base member is put on the resin rich area and laminated by a pressurization roll at a level lamination process 102, in a manufacturing method of the lens sheet. Then the same is cured by applying ionization radiation to the same at a thermosetting process 103, mold release is performed at the mold release and peeling process 104 and a base member is peeled off.

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, etc., and a method for manufacturing the same. The present invention relates to a thin lens sheet molded from only 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 involves pouring monomer into a mold and polymerizing it, which is time-consuming.
Since a large number of molds are required, there is a problem in that the manufacturing cost increases.

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 video projectors,'' ``a UV-curable resin is injected into a lens mold under normal pressure, and covered with an UV-transparent plate. The gist is to irradiate the ultraviolet curable resin filled between the transparent plate and the mold with ultraviolet rays that pass through the ultraviolet transparent plate to cure the resin, and then release the cured ultraviolet curable resin from the mold. Suggestions have been made.

〔Problems to be solved〕

The proposed method has 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 bottle set is used to stack the ultraviolet-transparent substrate on the ultraviolet-curable resin injected into the mold. It is proposed that one side should be in contact with the other side, and the other side should be gradually 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, when bubbles are mixed into the resin during injection, it is proposed to ``remove them using a pipette, etc.'' However, 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, in conventional lens sheets, the base plate has a thickness of 3
．． Since an acrylic plate with a thickness of about 0 mm was used, when used in a transmission type screen, etc., the optical properties around the screen were poor due to the thickness of the base plate, resulting in, for example, multiple images or rainbow colors. Unevenness sometimes occurred.

An object of the present invention is to solve the above-mentioned problems and provide a lens sheet that does not contain bubbles in the lens portion and has excellent optical properties, and a method for manufacturing the same.

[Disclosure of the invention]

As a result of various studies, the inventor of the present invention has achieved the above object by applying an ionizing radiation-cured resin to a mold through a base member while leveling it with a pressure roll, molding it, and peeling off the base member after molding. We have discovered what can be achieved and have come up with the present invention.

FIG. 1 is a diagram for explaining 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
A lens pattern is formed into a thin sheet using ionizing radiation-cured resin 1.

The lens pattern can be in the shape of a Fresnel lens, a prism lens, a Lentsch error lens, or the like.

The ionizing radiation curable resin 1 can be an ultraviolet curable resin or an electron beam curable resin, such as a polymerizable oligomer having an acryloyl group such as urethane acrylate, epoxy acrylate, polyester acrylate, polyether acrylate, or melamine acrylate;
Monomers and acrylic acid, acrylamide, and 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.

For such ionizing radiation-curable resins, it is better to use hexamers or prepolymers with multifunctional groups in order to improve general mechanical properties such as surface strength and hardness, and in reality, resins with two or more functional groups are used. are preferably used.

Further, since the lens sheet of the present invention does not include a base plate, the ionizing radiation-cured resin requires appropriate flexibility and mechanical strength. Furthermore, optically high transparency is required. In this case, the thickness of the entire lens sheet is determined based on the above performance and optical properties, and is 0.1 m.
It can be preferably carried out within the range of m-1 to 2 mm.

Furthermore, this ionizing radiation-cured resin can contain a diffusing agent. A diffusing agent can improve coating suitability, prevent polymerization shrinkage, and further impart diffusibility. As the diffusing agent, glass, silica, alumina, insoluble plastic, talc, etc. can be used.

Next, the method for manufacturing a lens sheet having the first configuration according to the present invention includes a resin coating step 101, a leveling and laminating step 102,
It consists of a resin curing step 103 and a mold release peeling 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 step, the ionizing radiation-cured resin functions to push out air bubbles that enter between the base member to be temporarily laminated and the mold. Methods for forming a resin pool of ionizing radiation-cured resin include the squeezing method,
Methods such as a flow coating method and a roll coating method can be used.

In the leveling and laminating step 102, an ionizing radiation-transparent base member is placed on the resin pool of the ionizing radiation-cured resin, and the ionizing radiation-cured resin is leveled onto the mold using a pressure roll through the base member. This is a step of laminating the base member on the ionizing radiation-cured resin. This step is a step that pushes out air bubbles that may have entered between the mold and the base member, and also serves to make the thickness of the molded product uniform.

Here, the base member may be any material as long as it is transparent to ionizing radiation, and for example, a transparent acrylic plate or the like may be used. Furthermore, a release agent or the like may be applied to the ionizing radiation-cured resin in order to impart releasability to the resin.

This base member may be a flat plate, but may be curved to enhance the defoaming effect when laminating the ionizing radiation-cured resin while leveling it with a pressure roll.

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

In this process, the resin is cured by irradiating it with ionizing radiation such as ultraviolet rays or electron beams.
It is preferable to bring the light source as close as possible to the roll pressing section. This is to prevent floating between the mold and the base member and to prevent air bubbles from being reintroduced between them.

The mold release peeling step 104 is a step of releasing the ionizing radiation-cured resin from the mold and peeling off the base member.

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

That is, the lens sheet of the second configuration according to the present invention is
The vicinity of the tip of the lens pattern is formed into a thin sheet shape using a first ionizing radiation-curable resin 11, and the base side of the lens pattern is formed using a second ionizing radiation-curable resin 12.

As shown in an enlarged view in FIG. 3B, the lens sheet of the second configuration has the following features except that it is composed of two layers: a first ionizing radiation-curable resin 11 and a second ionizing radiation-curable resin 12. Since this lens sheet is 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 as those mentioned above can be used, but the physical properties of the first ionizing radiation curable resin include mold transferability, defoaming property, 3 wettability to mold, 1
Emphasis is placed on surface hardening properties, and for the second ionizing radiation-cured resin, emphasis is placed on mechanical strength such as releasability from the base member, fluidity, transparency, rigidity that can replace the base plate, and flexibility.

In addition, the viscosity of the first ionizing radiation-cured resin is 2
A low viscosity adjusted to 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 one adjusted to centiboise 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 a certain 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, the base member, or the molded lens sheet itself can more effectively fulfill its respective functions, and these functions can be divided into two layers. This allows for a wider 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 Ti, H radiation curing resin are laminated is not necessarily flat, so if the refractive index of the two resins is significantly different, it will not be uniform. This is because light cannot be obtained.

If this relationship is satisfied, the first ionizing radiation curing resin and the second
The ionizing radiation curing resin may be the same material or may be a different material. In the case of different resins, a combination of substantially equal refractive indexes may be used in consideration of physical properties. For example, as the first ionizing radiation curing resin, a urethane acrylate resin with good mold reproducibility and high surface strength may be used. A flexible epoxy acrylate resin can be used as the second ionizing radiation curing resin. In addition, the first ionizing radiation curing resin and the second
Changing the resin temperature in the processing process of the ionizing radiation-cured resin, adding additives (antifoaming agents, leveling agents, etc.), solvents, etc., or adding the first ionizing radiation-cured resin and the second ionizing radiation-cured resin. Wettability to the mold can be improved by changing the compounding ratio of monomers, oligomers, etc. in the cured resin.

Fluidity, viscosity, etc. may be appropriately adjusted.

Furthermore, a diffusing agent can be included in both or one of the first ionizing radiation-curable resin and the second ionizing radiation-curable resin.

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 step 204 , and a mold release peeling step 205 .

The first resin coating step 201 is a step of coating the entire surface of the mold in which the lens pattern mold is formed with a first ionizing radiation-curable resin. 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.

The second resin coating step 1 step 202 is a step of forming a resin pool of the second ionizing radiation-cured resin at the end of the mold.

In the leveling and laminating step 203, an ionizing radiation-transparent base member is placed on the resin pool of the second ionizing radiation-curable resin, and the second ionizing radiation-curable resin is applied to the mold using a pressure roll through the base member. The base member is leveled over the first ionizing radiation-cured resin coated on the second ionizing radiation-cured resin.
This is the process of laminating 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 peeling step 205 is a step of releasing each of the ionizing radiation-cured resins from the mold and peeling off the base member.

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.

Although the present invention has been described as a lens sheet, the structure and manufacturing method of the sheet according to the present invention may be applied to any sheet having a fine pattern on its surface, and can also be applied to optical cards, optical disks, holograms, etc.

〔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, 1 is an ionizing radiation curing resin, 2 is a base member, 3 is a mold, 4 is a roll, and 5 is a U2 light source.

First, as shown in Fig. 5(a), the left end (
Ionizing radiation curing resin 1 was dropped onto the roll 4 side) by a flow coating method to form a resin pool of 1.0 g/ci. The ionizing radiation curing resin 1 has a refractive index of 1.4.
9. An epoxy acrylate UV curing resin whose viscosity was adjusted to 1500 centivoise was used.

Next, as shown in FIG.
acrylic plates are laminated and the pressure roll 4.4 is set at a speed of 50c.
Pressure was applied by transferring at m/min. At this time, air bubbles that enter between the mold 3 and the base member 2 are pushed out at a portion indicated by A in the figure. At this time, the UV light source 5 is
The ionizing radiation-curable resin 1 was cured by irradiating with ultraviolet (UV) light of 160 W/cm using the following method.

Finally, as shown in FIG. 5(C), the mold 4 is released and released, and the base member 2 is peeled off to a thickness of 0.2 mm.
A Fresnel lens sheet of mm was obtained. This lens sheet is composed only of the ionizing radiation-cured resin 1.

This Fresnel lens sheet did not contain air bubbles in the lens portion, and when used as part of a transmission screen, an image with good resolution and no color unevenness in the peripheral area was obtained.

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, 11 is a first ionizing radiation curing resin;
Reference numeral 2 denotes a second ionizing radiation curing resin, and parts that perform the same functions as in the previous embodiment are given the same reference numerals.

First, as shown in FIG. 6(a), a first mold
The ionizing radiation curing resin 11 has a refractive index of 1.49. A urethane acrylate UV curing resin adjusted to a viscosity of 100 centimeters is made to a thickness of 50 centimeters using the silk screen method.
It was applied to μm.

Next, as shown in Fig. 6), the second ionizing radiation-cured resin 12 is dropped onto the left end (roll 4 side) of the mold 3 by a flow coating method, and 1. A resin puddle of Og/cd was formed. The second ionizing radiation curing resin 12 has a refractive index of 1.49. An epoxy acrylate UV curing resin whose viscosity was adjusted to 1500 centivoise was used.

Furthermore, as shown in FIG. 6(C), a UV-transparent material with a thickness of 3.0 mm coated with a release agent is used as the base member 2.
acrylic plates bent to a radius of curvature of 6000 mm are laminated, and a pressure roll 4.4 is rolled at a speed of 50 c.
Pressure was applied by rolling at a speed of m/min. At this time, air bubbles that enter between the mold 3 and the base member 2 are pushed out at a portion indicated by A in the figure.

At this time, using the UV light source 5 from the base film 2 side,
The first ionizing radiation-curable resin 11 and the second ionizing radiation-curable resin 12 were cured by irradiating ultraviolet (UV) light at 160 W/cm.

Finally, as shown in FIG. 6(d), the mold 4 is released and released, and the base member 2 is peeled off to a thickness of 0.2 mm.
A Fresnel lens sheet of mm was obtained. In this lens sheet, the vicinity of the tip of the lens portion is composed of a first 1i ionizing radiation-curable resin 11, and the base side is composed of a second ionizing radiation-curable resin 1.
It is composed of 2.

This Fresnel lens sheet does not contain air bubbles in the lens part, especially on the surface, and when used as part of a transmission screen, it produces images with good resolution and no color unevenness in the peripheral area. was gotten.

Note that a similar lens sheet can be obtained by using a curved base member in the case of the embodiment shown in FIG. 5 and using a flat base member in the case of the embodiment shown in FIG.

〔Effect of the invention〕

As described in detail above, according to the present invention, since there is no thick base plate, the optical characteristics of the peripheral portion are improved when used in a Fresnel lens sheet or the like constituting a transmission type screen.

Furthermore, since the base member is placed on the ionizing radiation-cured resin and the coating is applied while leveling it with a pressure roll, air bubbles are no longer mixed into the lens portion even though it is not molded in a vacuum atmosphere.

Furthermore, since the first and second ionizing radiation curing resins having different properties were applied in separate steps, the defoaming property was further improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining 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 for explaining the lens sheet of the second configuration according to the present invention, and FIG. 4 is a flowchart for explaining the manufacturing method of the lens sheet of 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. ■... Ionizing radiation curing resin 11... First ionizing radiation curing resin 12... Second ionizing radiation curing resin 2... Base member 3... Molding die 4... Pressure roll 5 ...UV light source patent applicant Dainippon Printing Co., Ltd. Representative Patent attorney Kama 1) Second son Figure 1A Figure 3A Old figure Figure 3B Figure 2 Figure 5 Figure 6 Figure 6 Written amendment to the procedure filed by the person who made the amendment 1, Indication of the case: Patent application filed on January 28, 1988 (2) 2, Title of the invention: Lens sheet and its manufacturing method 3, Relationship with the person making the amendment case Patent applicant address ◎162-01 Ichigaya Kagacho, Shinjuku-ku, Tokyo-
Chome 1-1 Name (289) Dai Nippon Printing Co., Ltd. Representative Yoshitoshi Kitajima 4, Agent address ◎170 Higashiikebukuro, Toshima-ku, Tokyo - Chome 36-3-6 Number of claims increased by amendment None 7. Subject of amendment Detailed explanation of the invention in the specification Column 8, Contents of the amendment As shown in the attached sheet, the content of the amendment (1) "...adjustment" on page 13, line 16 of the specification. Correct as follows. [...You just need to adjust it. When adjusting using a solvent, it is desirable to volatilize the solvent after coating in order to prevent resin shrinkage, solvent deterioration, etc. "that's all

Claims (4)

[Claims] (1) A lens sheet in which a lens pattern is molded into a thin sheet using ionizing radiation-cured resin. (2) A resin coating step of forming a resin pool of ionizing radiation-curable resin at the end of the mold in which the lens pattern mold is formed, and placing an ionizing radiation-transparent base member on the resin pool of the ionizing radiation-curable resin. a leveling and laminating step of laminating the base member on the ionizing radiation-cured resin while leveling the ionizing radiation-cured resin onto the mold using a pressure roll via a base member; and applying ionizing radiation to the ionizing radiation-cured resin. A method for manufacturing a lens sheet comprising a resin curing step of curing by irradiation, and a mold release peeling step of releasing the ionizing radiation-cured resin from the mold and peeling off the base member. (3) A lens sheet in which the vicinity of the tip of the lens pattern is formed with a first ionizing radiation-curable resin, and the base side of the lens pattern is formed into a thin sheet shape with a second ionizing radiation-curable resin. (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 an ionizing radiation-transparent base member on the resin pool of the second ionizing radiation-cured resin, applying the second ionizing radiation-cured resin using a pressure roll through the base member. a leveling and laminating step of laminating the base member on the second ionizing radiation curable resin while leveling the base member on the first ionizing radiation curable resin applied to the mold; A method for manufacturing a lens sheet comprising a resin curing step of curing by irradiating with radiation, and a mold release peeling step of releasing each of the ionizing radiation-cured resins from the mold and peeling off the base member.