JP2007047588A - Method of manufacturing optical element including ultraviolet curable resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing optical element including ultraviolet curable resin which does not degrade transmittance of ultraviolet curable resin even when a large amount of ultraviolet rays is irradiated. <P>SOLUTION: A first means comprises a process of curing ultraviolet curable resin and, thereafter, performing a heating treatment. in a first means. In the first means, the heating treatment is performed in the range of 40°C to 130°C (a second means). In the first means, the heating treatment is performed in the range of 60°C to 100°C (a third means). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical element including an ultraviolet curable resin as an optical element.

  An optical element made of an ultraviolet curable resin or an optical element containing an ultraviolet curable resin as a part of an optical element is usually used in general (in the present specification and claims, these are collectively included). This is referred to as an “optical element containing an ultraviolet curable resin”.

  For example, an optical element in which a resin layer is molded on the surface of a base material is called a composite optical element. As the resin layer, an ultraviolet curable resin is often used. The UV curable resin layer is molded using a mold. Since the ultraviolet curable resin faithfully transfers the shape of the mold, an optical element having a desired surface shape can be obtained easily and at low cost. Further, since the ultraviolet curable resin is cured in a short time and does not use a heat source, the cost can be further reduced.

  In order to increase the durability of the optical element, it is necessary to sufficiently cure the ultraviolet curable resin. When a large amount of ultraviolet light is irradiated, the degree of curing increases, but there is a problem that the transmittance of the ultraviolet curable resin decreases (yellowness becomes stronger).

  The present invention has been made in view of such circumstances, and provides a method for producing an optical element including an ultraviolet curable resin so that the transmittance of the ultraviolet curable resin does not decrease even when a large amount of ultraviolet rays are irradiated. This is the issue.

  A first means for solving the above problem is a method for producing an optical element including an ultraviolet curable resin, comprising a step of performing a heat treatment after curing the ultraviolet curable resin.

  The second means for solving the problem is the first means, characterized in that the heat treatment is performed in a range of 40 ° C to 130 ° C.

The 3rd means for solving the subject is the 1st means, and performs the heat treatment in the range of 60 ° C-100 ° C.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical element containing an ultraviolet curable resin that the transmittance | permeability of an ultraviolet curable resin does not fall even if it irradiates a lot of ultraviolet rays can be provided.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a method for manufacturing an optical element including an ultraviolet curable resin, which is an example of an embodiment of the present invention.

  First, a substrate 1 made of glass is prepared. The substrate 1 may have a planar shape or may have optical power. Then, a silane coupling treatment is applied to the surface to which the ultraviolet curable resin is applied so as to enhance the adhesiveness (a).

  Next, the ultraviolet curable resin 2 is placed on the substrate 1, pressed between the mold 3 and pressed, and irradiated with ultraviolet rays through the substrate 1 to cure the ultraviolet curable resin 2. (B). Then, after the ultraviolet curable resin 2 is cured, the mold 3 is peeled from the ultraviolet curable resin 2 (c). In this state, the ultraviolet curable resin 2 is in a yellowish state under the influence of ultraviolet irradiation, and the transmittance is lowered.

  Subsequently, another ultraviolet curable resin 4 is placed on the ultraviolet curable resin 2 and pressed between the mold 5 and irradiated with ultraviolet rays through the substrate 1 and the ultraviolet curable resin 2. Then, another ultraviolet curable resin 4 is cured on the ultraviolet curable resin 2 (d). Then, after the ultraviolet curable resin 4 is cured, the mold 5 is peeled from the ultraviolet curable resin 4 (e). In this state, the ultraviolet curable resin 4 becomes yellowish under the influence of ultraviolet irradiation, and the transmittance is lowered.

  Subsequently, the optical element thus formed is placed in the heat treatment chamber 6 and heat treatment is performed (f). At this time, the transmittance can be improved even if the humidification treatment is performed simultaneously with the heat treatment. The temperature for the heat treatment is suitably 40 to 130 ° C. If it is less than 40 ° C., the effect is small, and if it exceeds 130 ° C., the resin is likely to deteriorate. 60-100 degreeC is especially preferable. 60% or more is appropriate as the humidity when the humidification treatment is performed together, and 80% or more is particularly preferable. If the humidity is less than 60%, the effect is small. Thus, the heat treatment (further humidification treatment added thereto) eliminates yellowing of the ultraviolet curable resin 2 and the ultraviolet curable resin 4 and improves the transmittance. The optical element is taken out from the heat treatment chamber 6 to complete a composite optical element composed of the substrate 1, the ultraviolet curable resin 2, and the ultraviolet curable resin 4 (g).

  As described above, the reason why the transparency is restored by the heat treatment and the humidification treatment is not clear, but it is presumed that there is an effect of accelerating the property that the transmittance naturally returns. In this embodiment, glass is used as the base material, but the base material may be a plastic such as an injection molding resin. The resin layer may be one layer, or two or more layers may be laminated. Further, it may be provided on both surfaces of the base material. The surface shape of the base material on which the resin layer is molded is not particularly limited, such as a spherical surface, an aspherical surface, or a diffractive optical surface. When the shape of the resin layer is aspherical, a composite aspherical optical element is obtained. When a diffractive optical surface is used, a composite diffractive optical element is obtained. Further, two or more resin layers may be laminated so that the interface is a diffractive optical surface.

Example 1
An optical material having a different refractive index and dispersion was laminated on a base material, and a close-contact multilayer diffractive optical element having a diffractive optical surface at its interface was produced. In order to use it as an optical material for a close-contact multilayer diffractive optical element, it is necessary to have a relatively high refractive index and low dispersion and a low refractive index and high dispersion.
(1) A resin precursor having a low refractive index and a high dispersion was prepared with the following composition.
53 wt% of fluorine-containing bifunctional acrylate, 42 wt% of bifunctional acrylate having a fluorene skeleton, and 5 wt% of monofunctional acrylate.

As a photopolymerization initiator, 0.5 wt% of Irgacure 184 (Ciba Specialty Chemicals) was added.
The physical properties after curing were as follows.

(2) A terminal acrylate oligomer obtained by reacting a bifunctional thiol with an excess of a bifunctional acrylate as a high refractive index and low dispersion resin precursor was prepared.
The molar ratio of bifunctional thiol to difunctional acrylate is 1: 2.5.
As a photopolymerization initiator, 0.5 wt% of Irgacure 184 (Ciba Specialty Chemicals) was added.
The characteristics of the cured product were as follows.

(3) As a sample for measuring transmittance, each of the resins (molded with a thickness of 0.2 mm) on glass (BK7) was produced. UV irradiation dose by the evaluation of the curing degree, low refractive index and high dispersion resin is 10000 mJ / cm ^2, a high refractive index and low dispersion resin was 6000 mJ / cm ^2.
After curing, heat treatment was performed at 70 ° C. for 20 hours. The transmittance was as follows including those left for 20 hours without heat treatment. (Measurement wavelength 380nm)

(4) A close-contact multilayer diffractive optical element was produced. The lattice shape has a diameter of 20 mm, a lattice height of 20 μm, a lattice pitch of 1.2 mm near the center, and 0.02 mm near the outer periphery, with the pitch becoming smaller toward the periphery. Silane coupling treatment was applied to the surface of the base material glass on which the resin layer was molded. The treated surface and the lattice-shaped mold were opposed to each other, and a low refractive index and high dispersion resin was filled therebetween. After curing by ultraviolet irradiation, the mold was released. Further, a continuous surface mold having no diffraction grating was made to face this time, and a high refractive index and low dispersion resin was filled therebetween. After curing with ultraviolet rays, the mold was released to obtain a contact multilayer diffractive optical element. The resin thickness and the UV irradiation amount are the same as in (3).
(5) The element was heat-treated at 70 ° C. for 20 hours. The transmittance was 5% higher than that of the element left for 20 hours without heat treatment.
(Example 2)
Instead of the heat treatment in Example 1 (3), a humidification treatment was performed at 60 ° C. and a humidity of 80% for 96 hours. Other steps are the same as those in the first embodiment. The transmittance of both resins increased as in Example 1. Further, the same humidification treatment was performed instead of the heat treatment of (5). The treated device was 4% higher in transmittance than the device that was left untreated for 96 hours.

It is a figure for demonstrating the manufacturing method of the optical element containing the ultraviolet curable resin which is an example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Ultraviolet curable resin, 3 ... Mold, 4 ... Ultraviolet curable resin, 5 ... Mold, 6 ... Heat treatment chamber

Claims (3)

A method for producing an optical element including an ultraviolet curable resin, comprising a step of performing a heat treatment after curing the ultraviolet curable resin. The method for producing an optical element containing an ultraviolet curable resin according to claim 1, wherein the heat treatment is performed in a range of 40 ° C to 130 ° C. The method for producing an optical element containing an ultraviolet curable resin according to claim 1, wherein the heat treatment is performed in a range of 60 ° C. to 100 ° C.

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