JPH0220328A - Optical element for ultraviolet region - Google Patents

Abstract

PURPOSE:To enhance a UV ray transmittance and a UV ray utilizing efficiency, prevent solarization and enhance durability by using an epoxy resin not containing any carbon-carbon unsaturated bond in the molecular structure thereof for an adhesive layer. CONSTITUTION:An optical element is used which has an adhesive layer comprising an epoxy resin adhesive not containing any carbon-carbon unsaturated bond (C=C or CidenticalC) in the molecular structure thereof in the condition of being used. A two-pack type consists of two components, namely, a main agent and a hardener. The main agent may be a compound not containing any unsaturated bond, such as double bond and triple bond, in the molecule thereof. Examples of the main agent include hydrogenated bisphenol A polyglycidyl ether and homologs thereof, and aliphatic or alicyclic polyhydric alcohols. The hardener is generally an aliphatic or alicyclic polyamine or an acid anhydride.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to optical elements such as laminated lenses and prisms,
In particular, it relates to optical elements for the ultraviolet region.

[Conventional technology]

Optical components such as lenses and prisms, whether made of glass or plastic, are composed of a single item (single block), but in order to satisfy diverse or strict optical characteristics, two or more optical components are used. Optical elements such as laminated lenses and prisms made by bonding members together with adhesive are often used. In this specification, an optical element obtained by bonding two or more optical members together with an adhesive is referred to as an optical element.

Traditionally, this type of adhesive has been made of natural resin balsam, synthetic resin epoxy, and ultraviolet curing type (acrylic).
has been used.

For a long time, it has been decided that optical elements must transmit visible light (wavelength λ = 41 · Or + m or more), and the constituent optical members as well as the adhesive are colorless and transparent (that is, have high transmittance for visible light). have been used.

The reason for using a colorless and transparent adhesive is that when using the optical element, visible light will pass through the adhesive layer.

Recently, interest in technological development has been shifting from visible light to ultraviolet light with a short wavelength λ. This is because the wavelength of ultraviolet light is λ
This is because high precision can be achieved because the length is short.

[Problem to be solved by the invention]

However, conventional adhesives are sensitive to ultraviolet light, especially when λ=200
The transmittance for ultraviolet light of ~400 nm was not very high.

Therefore, the first problem is that the efficiency of using ultraviolet rays is reduced.

Furthermore, when ultraviolet rays are absorbed by the adhesive, resin molecules are cut due to a photochemical reaction, and as a result, solarization, which is a deterioration in optical performance, is observed (second problem).

Besides, when UV radiation is absorbed by the adhesive, its energy is converted into heat and increases the temperature of the optical element, thus
The third problem is that when used continuously for a long time, the entire optical element expands thermally, causing the optical system to become out of order.

Furthermore, when the incidence of ultraviolet rays is stopped, the temperature of the optical element decreases to room temperature, and at this time it contracts. Therefore, there is a fourth problem in that the adhesive layer is destroyed by repeating the thermal expansion and contraction described above, and the optical element is cracked from there.

Therefore, the purpose of the present invention is to: 1) have high utilization efficiency of ultraviolet light in the wavelength range of λ-200 to 400 nm, 2) have little solarization, and 2) prevent the optical system from becoming distorted even when used continuously for a long time.
Moreover, the objective is to provide an optical element that is hard to break (highly durable).

[Means to solve the problem]

As a result of intensive research on hundreds of types of adhesives, the present inventors found that the adhesive layer has a carbon-carbon unsaturated bond (C= C
The present inventors have discovered that an optical element made of an epoxy resin adhesive that does not contain C=C) does not have the first to fourth problems described above, and has accomplished the present invention.

Therefore, the present invention provides a first optical member and a second optical member that transmit ultraviolet light having a wavelength of λ = 200 to 400 nm, which are bonded together via an adhesive layer; The present invention provides an optical element for use in the ultraviolet region, characterized in that the adhesive layer is made of an epoxy resin that does not contain a carbon-carbon unsaturated bond in its molecular structure.

Incidentally, all epoxy resin adhesives commercially available to date have contained the unsaturated bonds mentioned above. [Function] The epoxy resin adhesive used in the present invention has ill There are saturated types and (2) unsaturated types, both of which belong to thermosetting resins.

The +11 saturated type is generally a two-component type, which is liquid before adhesion, undergoes reaction curing during adhesion, and develops strong adhesive force after reaction curing.

The two-part type consists of two components: a base agent and a curing agent.

The base agent has a relatively low molecular weight and has at least two epoxy groups in its molecule, and is generally liquid. Depending on the case, it may be solid and liquefied with a diluent (including a reactive diluent).

The base agent must not contain unsaturated bonds such as a C═C double bond or a C═C triple bond in its molecule. Examples of such main agents include hydrogenated bisphenol A polyglycidyl ether and its homologues, hydrogenated bisphenol F polyglycidyl ether and its analogs, resorcinol polyglycidyl ether and its analogs, and other aliphatic or alicyclic Polyhydric alcohols (e.g., ethylene glycol, diethylene glycol, propylene glycol, 1,4 butylene glycol, glycerin, hexanetriol, trimedyllolpropane, pentaerythritol, sorbitol, sucrose, dipropylene glycol, neopentyl glycol, 1,6 polyglycidyl ethers of hexamethylene glycol, decamethylene glycol, etc., and oligomers thereof) and their analogues, epoxidized polyolefins (e.g., epoxidized polybutadiene), vinylcyclohexene dioxide, dicyclopentadiene dioxide, methylcyclohexane carbonate systems Examples thereof include oxide, alicyclic glycidyl ester such as dimethylglycidyl hexahydrophthalate, and the like.

The curing agent generally used is (1) an aliphatic or alicyclic polyamine, or (2) an acid anhydride.

Examples of the former ■ include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, pentanediamine, hexamethylenediamine, aminoethylpiperazine, dicyandiamide, methyljetanolamine, ethyldiisopropanolamine, Examples include aliphatic or alicyclic polyamines such as ethanolamine and bis(p-aminocyclohexyl)methane.

Examples of the latter ■ include acetic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride, polyadipic anhydride, polyazelaic anhydride, polysebacic anhydride, and polyethyl octadecanedioic anhydride. Examples include acid anhydrides such as. Both must not contain unsaturated bonds in their molecules.

(2) Unsaturated type is obtained by reacting the above-mentioned main agent with an equivalent amount of unsaturated fatty acid, and has a C=C double bond or a C30 triple bond in its molecular structure, but it no longer substantially contains an epoxy group. have no purpose.

Examples of the unsaturated fatty acids used include acrylic acid, methacrylic acid, angelic acid, crotonic acid, elaidic acid, oleic acid, glutaconic acid, vinyl acetic acid, and the like.

Unsaturated systems have unsaturated bonds in their molecular structure, so by applying energy such as heat, ultraviolet rays, radiation, X-rays, electron beams, gamma rays, etc., vinyl polymerization occurs and reaction hardening occurs. be able to. In this case, photopolymerization initiators such as biacetyl, camphorquinone, hensyl,
2.3-pentadione, β-naphthoquinone, acenaphthenequinone, benzophenone, benzoin ethyl ether, benzoyl-1-hydroxycyclohexane, etc. may be added.

〔Example〕

Two quartz lenses with high transmittance for ultraviolet light were prepared.

Next, using 100 parts by weight of hydrogenated bisphenol A glycidyl ether as the main ingredient and 80 parts by weight of hexahydrophthalic anhydride as the hardening agent, both were mixed uniformly, and this was poured onto one surface of the lens. The other lens was pressed from above and left at 130° C. for 3 hours to cure the adhesive.

A cross section of the optical element of this example thus obtained is shown in FIG. The thickness of the adhesive layer is approximately 5 microns.

[Comparative example]

As the adhesive, a commercially available epoxy adhesive (a two-component type in which the main ingredient is bisphenol A glycidyl ether and the curing agent is anhydrous phthalate) was obtained, and 100 parts by weight of the main ingredient,
75 parts by weight of each curing agent were weighed out, and optical elements were produced in the same manner as in the examples.

[Test example]

Regarding the optical elements of Examples and Comparative Examples, (11) the adhesive strength of the adhesive layer and (2) the spectral transmittance in the ultraviolet region were investigated.

As a result, fl) adhesive strength was approximately 140 kg for both.
/cd, and (2) the spectral transmittance in the ultraviolet region was as shown in FIG.

Comparing the integrated value of spectral transmittance in the ultraviolet region of λ-200 to 400 nm (corresponding to the area of the hatched part in Fig. 3.4), Example: Comparative Example-83: 48, and Example. It is understood that the optical element has high transmittance in the ultraviolet region.

〔Effect of the invention〕

As described above, according to the present invention, ultraviolet rays (λ=200 to 4
00nm), and as a result: ■high ultraviolet ray utilization efficiency; ■less solarization; ■even if used continuously for long periods of time, the optical system may become distorted. element is obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an optical element according to an embodiment of the invention. 2 to 4 are graphs of spectral transmittance. [Explanation of symbols of main parts] 1 -----------First member 2------------------Second member 3--
-----------One adhesive layer■ 1st

Claims (1)

[Claims] A first lens that transmits ultraviolet light having a wavelength λ of 200 to 400 nm.
In an optical element for an ultraviolet region in which an optical member and a second optical member are bonded via an adhesive layer, and the ultraviolet rays are transmitted through the adhesive layer, the adhesive layer has carbon-carbon unsaturation in its molecular structure. An optical element for the ultraviolet region characterized by being made of an epoxy resin that does not contain bonds.