JPS62258401A - Aspherical lens - Google Patents

Abstract

PURPOSE:To lower the rate of shrinkage by curing and to provide excellent shape accuracy by subjecting a compsn. contg. a specific (meth)acrylate and photopolymn. initiator to polymn. curing by UV rays to form a resin layer curable by UV rays. CONSTITUTION:The compsn. contg. the bi- - tetrafunctional urethanemodified polyester (meth)acrylate obtd. by bringing a diisocyanate and the (meth)acrylate having a hydroxyl group in the molecule into reaction with a polyester oligomer obtd. by bringing a polybasic acid and polyhydric alcohol into reaction, trifunctional (meth)acrylate, monofunctional (meth)acrylate and the photopolymn. initiator is subjected to the polymn. curing by the UV rays to form the resin layer curable by UV rays on the surface of an aspherical lens. The aspherical lens provided with the high shape accuracy is thus obtd. without spoiling the various characteristics such as high-temp. and high-humidity environmental resistance characteristic and hardness necessary as an optical lens.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to photographic cameras, video cameras, microscopes,
An aspherical lens that constitutes an optical system such as a telescope or an optical disk pickup component, and is characterized by having an ultraviolet curable resin layer provided in a desired shape on the surface of a glass lens as a base material. Regarding.

[Conventional technology]

Conventionally, there have been many examples of using ultraviolet curable resin in the resin layer of aspherical lenses such as those mentioned above, but conventional ultraviolet curable resin compositions do not have good heat resistance, moisture resistance, hardness, etc. after curing. It has been impossible to achieve both of this and increasing the shape accuracy during hardening and molding.

For example, among the conventionally used photocurable acrylate resins, polyfunctional ones have good light transmittance and hardness as lens materials, and also have good resistance to high temperature and high humidity environments and light resistance. Another problem was that the curing shrinkage rate was large, making it difficult to achieve shape accuracy.

In addition, the recently developed UV-curable epoxy resin has a shrinkage rate of about 3%, which is smaller than the shrinkage rate of conventional acrylate resins, which is about 8-9%, making it easier to achieve the desired shape precision. . However, since photocurable epoxy resins use acid catalysts to initiate polymerization, they have poor high-temperature environment resistance, and they also have problems with light resistance, which is thought to be due to the coloring characteristic of epoxy. It was difficult to put it into practical use.

In order to solve the above-mentioned problems with the resin itself, a lens with a two-layered resin layer is known (Japanese Patent Laid-Open No.
-56544). This is because the shrinkage rate is relatively low (it is easy to achieve shape accuracy, but the hardness is low, it easily absorbs moisture, and therefore has poor resistance to high temperature and high humidity environments). This lens is equipped with a thin layer of multifunctional ultraviolet-curable acrylate resin that has good properties in high-temperature, high-humidity environments and is highly hard. This lens has excellent characteristics in each layer, but in order to manufacture it, the UV curing process must be performed twice, which increases production equipment and lengthens the process, taking up space and time. Since this method has several problems and leads to an increase in costs, it can only be applied to large-lot products, making it difficult to put it into practical use.

Furthermore, in order to solve the above-mentioned problems with the resin itself, a molding method is known in which pressure is applied during curing. In this method, when curing a resin composition made of polyfunctional acrylate, pressure is applied in a direction to narrow the distance between the base lens and the mold. If this method is used, the precision of the shape of the molded resin will increase, or it will be necessary to apply a certain amount of pressure as low pressure is not very effective. As a result, there is a risk that the base material lens may break during the process, resulting in the problem that it can only be used for lenses made of strong materials or thick lenses.

The present invention was made in view of the above-mentioned problems, and its purpose is to improve the hardness of ultraviolet-effect acrylate resin, resistance to high temperature and high humidity environments, good light transmittance, light resistance, etc. for optical lenses. It is an object of the present invention to provide an aspheric lens provided with a surface layer having a roughly small curing shrinkage rate without impairing necessary physical properties. Another object of the present invention is to provide an aspherical lens in which the surface layer (ultraviolet curing resin layer) has a single-layer structure and can achieve excellent shape accuracy without applying pressure.

[Means for solving problems]

The above-mentioned object of the present invention is to provide an aspherical lens in which a UV-curable resin layer is provided in a desired shape on the surface of a glass lens serving as a base material, wherein the UV-curable resin layer contains (A) a polybasic acid and a polyhydric acid. 2 obtained by reacting a polyester oligomer obtained by reacting an alcohol with a diisocyanate and a (meth)acrylate having a hydroxyl group in the molecule.
A composition containing ~tetrafunctional urethane-modified polyester (meth)acrylate, (B) trifunctional (meth)acrylate, (C) monofunctional (meth)acrylate, and (D) photopolymerization initiator was polymerized and cured with ultraviolet rays. This is achieved by an aspherical lens.

FIG. 1 shows the structure of the aspherical lens of the present invention.

The aspherical lens of the present invention includes a base material 1 and an ultraviolet curable resin layer 2 laminated thereon.

The base material is an inexpensive lens made by spherical polishing of ordinary optical glass. The ultraviolet curable resin layer 2 is thinner than the base material, usually has an average thickness of 10 to 300 μm, and has an aspherical shape that is rotationally symmetrical with respect to the optical axis.

The lens of the present invention is produced by pouring a certain amount of ultraviolet curable upper Zimmer liquid into an aspherical mold having a transfer layer opposite to the desired aspherical shape, and placing the base material lens on which the aspherical shape is to be formed. It is obtained by fixing the surface facing the mold surface so as to maintain a constant distance from the mold, irradiating ultraviolet rays from the lens side, polymerizing and curing the monomer without applying pressure, and then peeling off the mold. .

The aspherical lens of the present invention is limited to one in which a resin layer is provided on the convex side of the base material as shown in Fig. 1.As a modified example, as shown in Fig. 2, a resin layer is provided on the concave side of the base material lens. Alternatively, as shown in FIG. 3, resin layers may be provided on both sides of the base lens. Generally, in order to improve the adhesion between the resin and the glass, as shown in Figure 5, it is also possible to apply a silane coupling material, etc., which is usually used to improve adhesive strength, to the glass surface and then apply the resin layer. .Also, after providing the resin layer,
As shown in FIG. 6, one or more layers of a protective layer for moisture proofing and a vapor deposited film for preventing reflection may be provided on the resin layer.

The present invention is intended for aspherical lenses, Funerel lenses, camera focusing plates, beam splitters, etc.
It can also be applied to applications where a repeating chevron shape as seen in elements (Fig. 4) is provided.

(A) component, (B) component, (C) component, (D) forming the ultraviolet curable resin layer 2 used in the aspherical lens of the present invention
The ingredients will be explained below.

Component (A) has a main chain skeleton of a polyester oligomer made of a polyhydric alcohol and a polybasic acid, and this polyester oligomer is composed of at least a dihydric alcohol or a dihydric alcohol.
It was synthesized using ~41M base acid. (A
) component has a hydroxyl group at the end of the main chain and side chain of this polyester oligomer (this is bonded to an incyanato group at one end of the diisocyanate, and a hydroxyl group is bonded to the incyanato group at the other end of the diisocyanate in the molecule ( 2~ consisting of meth)acrylates combined
It is a tetrafunctional urethane-modified polyester (meth)acrylate.

The 41M base acid is pyromellitic anhydride, 2.3
．． 3′,4=-biphenyltetracarboxylic dianhydride,
Hensiphenotetracarboxylic dianhydride, bis(3,
41 such as 4-dicarboxyphenyl)methane dianhydride
M groups, M, etc. are used.

Examples of the tribasic acids include tribasic acids such as trimellitic anhydride; dolomerintoic anhydride, 2,3.3',4'- and noenyltetracarboxylic dianhydride, and benzophenonetetracarboxylic dianhydride. Tribasic acids obtained by partially esterifying tetrabasic acids such as anhydrides and bis(3,4-dicarboxyphenyl)methane dianhydride are used.

In addition, as dibasic acids, notaric anhydride, inphthalic acid, terephthalic acid, succinic acid (anhydride), azidic acid, acelaic acid, sebacic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, himic anhydride, Maleic acid, fumaric acid, itaconic acid, etc. are used.

The trihydric or tetrahydric alcohol includes glycerin,
Trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol monoallyl ether or hentaerythritol are used.

Examples of dihydric alcohols include ethylene glycol, propylene glycol, neobesityl glycol, diethylene glycol, dibutyl alcohol, hydrogenated bisphenol A, 2,2'-di(4-hydroxypropoxyphenyl)propane, 1°3- Butanediol, 1.
4-butanediol, 1,5-bentanediol, 1,
6-hexanediol, trimethylene glycol, trimethylene glycol, becitaerythritol diallyl ether, etc. are used.

Examples of the diincyanate include tolylene diisocyanate, 4,4"-diphenylmethane diisocyanate,
Xylylene diisocyanate, hexamethylene diisocyanate, inphorone diisocyanate, lysine diisocyanate, hydrogenated xylylene diisocyanate, etc. are used.

Examples of the (meth)acrylates having a hydroxyl group in the molecule include 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene gellicol mono(meth)acrylate, and glycerin. Monoacrylate, glycericidiacrylate, etc. are used.

Component (A) is obtained by condensing a polyhydric alcohol and a polybasic acid to obtain a polyester oligomer, followed by an addition reaction with a diisocyanate, and then an addition reaction with a (meth)acrylate.

As component (A), the general formula (R is hydrogen or methyl group, R' is -C00Cn H2n
It is also possible to use incyanates having an unsaturated group represented by - (n is an integer of 1 to 8); in this case, the hydroxyl group at the terminal part of the main chain and side chain of the polyester oligomer can be used. 2. Urethane-modified polyester (meth)acrylate can be obtained by reacting isocyanate groups. The incyanates are, for example, 2-
Isocyanate methyl (meth)acrylate, 2-isocyanate ethyl (meth)acrylate, 2-isocyanate prodol (meth)acrylate, 2-isocyanate octyl (meth)acrylate, P-impropenyl-α, α-dimethylbenzyl isocyanate, m -isopropenyl-α, α-dimethylhenzyl isocyanate, P-ethylenyl-〇, α-dimethylhensyl isocyanate, mountain-ethylenyl-α, α-dimethylhensyl isocyanate, and the like.

As the trifunctional (meth)acrylate of component (B),
Trimethylolpropane tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(hydroxypropyl)
Examples include tri(meth)acrylate of isocyanurate.

As the monofunctional (meth)acrylate of component (C),
For example, methyl (meth)acrylate, ethyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, inbornyl (
meth)acrylate, boronyl(meth)acrylate,
Phenyl (meth)acrylate, halogen-substituted phenyl (meth)acrylate, hensyl (meth)acrylate, α-naphthyl (meth)acrylate, β-naphthyl (
Examples include meth)acrylate, dicyclobentyloxyethyl ararylate, etc.

As the photopolymerization initiator of component (D), hensifhenone, hydroxyhensiphenone methanesulfonate ester, 0-hensiphenone, p-chloropendinoenone, p-dimethylamine hensifhenone, etc. Substituted derivatives of hengeyne, hengeyne and hengeyne allyl ether, substituted derivatives of hengeyne such as hengeyne alkyl ethers where the alkyl group is methyl, ethyl, isobutyl, isopropyl etc., acetonoenone and jetoxyacetophenone, 1-hydroxyethylhexylphenyl ketone , benzyl dimethyl ketal, 2
-Hydroxy-2-methylpropiophenone, 1-(4
W1-substituted derivatives of acetonoenone such as -isopropylphenyl)-2-hydroxy-2-methylpropiophenone, hensyl, and oxime compounds such as 1-phenyl-1,2-brobanedione-2-〇-henzoyloxime, etc. One or more selected types are used.

The condensation reaction during the synthesis of the polyester oligomers of components (A) and (B) may be carried out by a heating reaction using a known method. For example, after charging the raw materials, the reaction is carried out at 150 to 250°C with stirring, and the acid value is The reaction ends when the target value is reached.

In the above, the ratio of polybasic acid to polyhydric alcohol used is preferably around 1:2 in equivalent ratio, but it can be changed depending on the molecular weight, the number of remaining alcohol groups, etc.

In the ultraviolet curable resin layer of the aspherical lens of the present invention, the component (A) is a component for maintaining good environmental resistance such as moisture resistance, heat resistance, and ultraviolet resistance, and usually has a weight of 10 to 90%. %, preferably 25 to 70% by weight. If it is less than 10% by weight, the environmental resistance will be poor, and if it exceeds 90% by weight, the viscosity will increase significantly and workability will deteriorate.

Component (B) is a component for improving physical properties such as hardness and heat distortion temperature, and is usually used in an amount of 10 to 70% by weight. 1
If it is less than 0% by weight, no improvement in the physical properties is desired, and if it exceeds 70% by weight, the cured product will become brittle, the shrinkage rate during curing will increase, and processing accuracy will deteriorate.

In addition, component (C) is a component for adjusting the balance of fluidity, viscosity, physical properties of cured product, etc. during molding of the ultraviolet curable resin layer of the aspherical lens of the present invention, and is used in a desired amount. Or, it is usually about 20 to 400 parts by weight per 100 parts by weight of the resin composition containing (A) and (B).

Component (D) is a component that has the ability to absorb irradiated light and initiate polymerization, and is used in a desired amount based on curability, physical properties of the cured product, etc., or is usually used in the above (A) to (C ) resin composition (about 0.5 to 10 parts by weight).

If necessary, known polymerization accelerators, polymerization inhibitors, M type agents, surface smoothing agents, antifoaming agents, etc. can be added to the ultraviolet curable resin layer of the aspherical lens of the present invention.

The light source used for ultraviolet irradiation includes a chemical lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a carbon arc lamp, a xeno lamp, and the like.

(Example) Next, the present invention will be roughly and concretely explained using examples.

Production Example-1 A four-eye flask equipped with a condenser, a nitrogen gas inlet tube, a thermometer, and a stirrer was charged with trimetic anhydride 969, propylene glycol 2289, and phthalic anhydride +119 @ and heated and stirred under a nitrogen atmosphere.

After raising the temperature to 150°C, it was held for 2 hours, and then the temperature was gradually raised to proceed with the reaction at 200°C, and the reaction was terminated when the acid value became 5 or less. After cooling to room temperature, inphorone diisocyanate 2779.2-hydroxyethyl acrylate 1
749, dibutyltin dilaurate 0.179 was added and the mixture was reacted for 3 hours while being heated gently so that the temperature of the reaction system did not exceed 80°C. After raising the temperature to 100°C over 1 hour, the mixture was reacted for 3 hours. Urethane-modified polyester aurilate (I) was obtained.

Production Example-2 Trimethylolpropane 549 was prepared in the same manner as Production Example-1.
, Tetrahydrophthalic anhydride 1829.1.3-Butylene glycol 1089@Charge and heat and stir under nitrogen atmosphere. After raising the temperature to 150°C, it was held for 2 hours, and then the temperature was gradually raised to proceed with the reaction at 200°C, and the reaction was terminated when the acid value reached 5 or less.

After cooling to room temperature, inphoron diisocyanate 2229
, hydroxypropyl aurelate 1569, dibutyl pot dilaure-t-0,I4c+ % was added, and after reacting for 3 hours while gently heating the reaction system so that the temperature did not exceed 80°C, the mixture was heated to 100°C for 1 hour. After raising the temperature for 3 hours, the urethane-modified polyester acrylate (
II) Obtained V.

Physical property test of aspherical lens Test examples 1 to 6 Above manufacturing example 1.
The urethane-modified polyester acrylate obtained in 2 was mixed with the other components shown in Table 1 in the proportions shown in the same table to form six types of compositions (resin layer compositions according to the present invention), 2 and comparative compositions 1 to 4) were obtained.

These compositions were Φ-40.5mm, R1=41
．． 34mm convex, day 2 = 203mm concave, center thickness 11.3
3mm, on the R1 convex side of the base material spherical lens of material 8 and 7,
A spherical resin layer was provided according to the above manufacturing method so that the center thickness was 150 μm and 8.41.49 mm, and 6f! A similar complex spherical lens was obtained.

(1) Shape Accuracy The surface shape of the composite spherical lens obtained as described above was observed using a Zygo interferometer, and the shape accuracy was determined from the disturbance of the obtained interference fringes. The results are shown in Table 1.

(2) Curing shrinkage rate Based on JIS-7112, measure the specific gravity before curing (liquid) and after curing (the casting plate) using a vicinometer, and divide the difference in specific gravity by the specific gravity after curing. It was defined as curing shrinkage rate.

(3) High-temperature and high-temperature environment resistance The obtained lens was placed in a high-temperature, high-humidity tank at 70°C and 85%RH for 5 minutes.
Leave it for 00 hours, observe the appearance before and after leaving it, and observe it under a microscope (×20
0), shape accuracy, etc. were checked.

(4) Pencil hardness A scratch test was conducted on the lens surface using pencils of various hardnesses, and the highest hardness that did not leave any scratches on the resin surface was defined as the pencil hardness.

For comparative compositions 1 to 4, the shape accuracy was ±1.2 μm.
However, in contrast, the resin layer composition according to the present invention], 2 has a shape accuracy of ±0.
It showed a good value of 6 μm or less, and could be fully used as an optical lens for photography, and no deterioration in high-temperature environment resistance or hardness was observed.

Example] A lens having the same shape as an aspherical lens used in a commercially available single-lens reflex camera lens was prepared using the composition 1 of the resin layer according to the present invention, and the shape was measured using a shape Im tactile aspherical surface measuring machine. The measurement results are shown in Figure 7. When measured with n・2, the maximum error was 0.
The diameter was within 5 μm, and it was confirmed that when this resin compound was used, an aspherical shape could be formed with good precision.

〔Effect of the invention〕

As described above, the composite aspherical lens of the present invention has a high degree of shape accuracy without sacrificing the essential properties necessary for an optical lens such as high-temperature environment resistance and hardness, and an ultraviolet curable resin layer. Since it has a single-layer structure, no extra production equipment is required, the production process is shortened, and the downward cost is reduced, making it possible to produce small lots. ・In addition, the curing shrinkage rate of the ultraviolet curable resin layer is low. Since it is small and does not require pressure during curing, it can be used for lenses made of materials that break easily when pressure is applied or thin lenses, making it possible to create optical designs with a wide range of lens shapes and materials (refractive index). There are effects such as .

[Brief explanation of drawings]

FIG. 1 is a sectional view of the aspherical lens of the present invention, FIGS. 2, 3, 5, and 6 are other embodiments of the aspherical lens of the present invention, and FIG. 4 is a sectional view of the aspherical lens of the present invention. FIG. 7 is a graph showing the measurement results of the shape accuracy of an aspherical lens, which is a composite optical element having a repeated chevron shape. 1: Base glass base 1a: Base of composite optical element 2: Aspherical resin layer

Claims (1)

[Claims] An aspherical lens in which an ultraviolet curable resin layer is provided in a desired shape on the surface of a glass lens serving as a base material, the ultraviolet curable resin layer comprising (A) a polybasic acid and a polyhydric alcohol; 2- to 4-functional urethane-modified polyester (meth)acrylate and (B) trifunctional (meth)acrylate obtained by reacting a polyester oligomer obtained by the reaction with a diisocyanate and a (meth)acrylate having a hydroxyl group in the molecule. An aspherical lens characterized in that it is obtained by polymerizing and curing a composition containing (C) a monofunctional (meth)acrylate and (D) a photopolymerization initiator using ultraviolet rays.