JP2006220689A - Optical material, optical element and its molding method, diffractive optical element, and diffractive optical element and optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optimum ITO fine particle dispersion optical material which has excellent dispersion stability, has an excellent optical characteristic, that is, high light transparency and low optical scattering property, exhibits a refractive index high dispersion characteristic and a secondary dispersion characteristic and is capable of forming moldings, and to provide an optical element using the optical material. <P>SOLUTION: This invention relates to a fine particle dispersion type optical material, a molding method of an optical element using the optical material, an optical element molded by the molding method, a diffraction optical element, a multi-layer diffractive optical element and an optical system having the optical element. This invention further relates to an ultraviolet curable optical material in which ITO fine particles are dispersed in resin including at least a photopolymerization initiator, a dispersion agent and at least two acrylic groups, methacrylic groups or vinyl groups, or a mixture of the unsaturated ethylenic groups. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical material used for an optical element such as a diffractive optical element. In particular, the present invention relates to an optical material having a high refractive index dispersion and an optical system having an optical element, a diffractive optical element, and a laminated diffractive optical element molded thereby.

  Conventionally, in a refractive optical system configured only by light refraction, chromatic aberration is reduced by combining glass materials having different dispersion characteristics. For example, in an objective lens such as a telescope, a glass material with small dispersion is used as a positive lens and a glass material with high dispersion is used as a negative lens, and these are used in combination to correct chromatic aberration appearing on the axis. In this case, it is very difficult to sufficiently correct chromatic aberration when the configuration and number of lenses are limited, or when the number of glass materials used is limited.

SPIE Vol.1354
International Lens Design Conference (1990) discloses a method of reducing chromatic aberration by using a diffractive optical element having a diffraction grating on a lens surface or a part of an optical system. This utilizes the physical phenomenon that the direction in which chromatic aberration occurs with respect to a light beam having a certain reference wavelength is reversed between the refracting surface and the diffractive surface as an optical element. Furthermore, such a diffractive optical element can have the same effect as an aspherical lens by changing the period of the periodic structure of the diffraction grating. Therefore, there is a very great effect in reducing chromatic aberration.

  In a material having a high refractive index dispersion and a material having a low refractive index dispersion, the greater the difference in refractive index dispersion, the higher the diffraction efficiency of the configured optical element, and the wider the angle of view of the optical element. For this purpose, it is necessary to use a material having a higher refractive index dispersion (small Abbe number), whereby chromatic aberration can be corrected more accurately.

  However, in order to further improve the function of the diffractive optical element, simply using a material having a high refractive index dispersion (small Abbe number) increases the diffraction efficiency in the entire visible region, but in the wavelength region used. A drop in diffraction efficiency partially occurs, and the reduction in diffraction efficiency is particularly remarkable in the short wavelength region. Therefore, by using an optical material that considers the relationship between the refractive index (nd), Abbe number (νd), and second-order dispersion (θg, F), the diffraction efficiency in the entire visible region is improved, and in each wavelength region. An optical material that does not cause a partial drop in diffraction efficiency is disclosed (Patent Document 1). In Patent Document 1, in order to impart such characteristics, it is mentioned that transparent conductive metal oxides such as ITO, ATO, and ZnO are mixed and dispersed as fine particles in a binder resin.

  However, from the viewpoint of dispersion stability of fine particles, an optical material that sufficiently satisfies the optical performance has not been obtained.

  Here, a conventional method for mixing and stabilizing fine particles in a resin will be described below.

  When utilizing the properties of non-organic substances such as inorganic salts and metals as characteristics of materials having excellent optical properties and molding processability, generally, a technique of dispersing the non-organic materials as fine particles in an organic resin material is used. In addition, when such a method is used for an optical material that requires a high degree of transparency and low scattering characteristics, the fine particles generally have a refractive index difference from that of the binder resin. It is necessary to make the particle size at least smaller than the wavelength of light to be used. Further, in order to reduce attenuation of transmitted light intensity due to Rayleigh scattering, it is particularly preferable to prepare and disperse nanoparticles having a particle size of less than about 15 nm with a particle size distribution as narrow as possible. Is the state-of-the-art research subject.

  In particular, in an optical member such as a lens, it is necessary to reduce scattering particularly due to problems such as flare. Ultrafine particles (primary particles) such as fine inorganic substances have a very strong cohesive force and aggregate into secondary particles in which the primary particles are aggregated in clusters in the production process of powder or dispersion process in a solvent or binder resin. To do. For this reason, when ultrafine particles are contained in the resin matrix, it is generally recognized that it is necessary to disperse in a state where secondary aggregation is reduced as much as possible. In order to solve such problems, there has been proposed a technique for dispersing and stabilizing fine particles by a dispersion device, addition of a dispersant, and a surface modification method of ultra fine particles.

  As a method of dispersing the fine particles in the resin using a dispersing device, the fine particles are directly added to the resin, and a known pulverizer / mixer / disperser (for example, a ball mill, a vibration ball mill, a planetary ball mill, a stirring ball mill, It is known to use an annula type ball mill, vertical sand mill, roller mill, pin mill, spike mill, coball mill, caddy mill, horizontal sand mill, attritor, sand mill, sand grinder, homogenizer, ultrasonic disperser and the like.

  Further, when the resin has a high viscosity and is difficult to disperse, a method of diluting the resin with a solvent and dispersing it, or dispersing fine particles in a solvent in advance and then mixing with the resin is employed. At that time, an appropriate amount of a dispersant may be used. In Patent Document 2, when silicone oil or the like is used as a dispersion medium, a dispersion of titanium oxide ultrafine particles is prepared using a silicone-based surfactant such as polyether-modified silicone as a dispersant. A homogenizer and homomixer are used for mixing and dispersion.

  Patent Document 3 describes that titanium oxide ultrafine particles are dispersed in an aqueous solvent using polyphosphate as a dispersant. As the dispersing device, a sand grinder, dyno mill, ball mill, and other various mixers, as well as a continuous or batch mixer or kneader are preferably used. Patent Documents 4 and 5 describe mixing an inorganic fine particle dispersion and a cationic polymer using an ultrasonic disperser or a high-pressure disperser.

  As a surface modification technique, Patent Document 6 discloses a technique relating to a resin composition in which trialkoxysilanes are bonded to the surface of titanium oxide ultrafine particles and dispersed in a resin matrix. Patent Document 7 discloses a technique in which a polymerizable organic compound or the like is bonded to the surface of oxide ultrafine particles such as silicon oxide, aluminum oxide, and zirconium oxide and dispersed in a crosslinked resin matrix. Patent Document 8 discloses a technique for improving the dispersibility of titanium oxide ultrafine particles in a resin matrix using modified polysiloxanes.

  In addition, for the purpose of imparting the characteristics of the optical material described in Patent Document 1 or not, the transparent conductive metal oxide such as ITO is dispersed and mixed in the resin as fine particles as follows. Are disclosed.

  Although there is no description of a specific dispersing agent in Patent Document 9, ITO, ATO fine particles and the like are previously mixed with an organic solvent containing a dispersing agent such as water and toluene by using a ball mill, and later on a polycarbonate resin. A blender blended sheet material with excellent visible light transmittance is provided. Patent Document 10 provides a transparent conductive film by preparing a slurry of irregularly shaped ITO fine particles using an anionic surfactant and ethanol and propanol as solvents.

  Similarly, Patent Document 11 provides an interlayer film for laminated glass by finely dispersing a layered silicate in a polyvinyl acetal resin containing ITO fine particles and having a heat shielding performance using a dispersant.

JP 2000-042600 A JP 2002-338245 A JP 2001-164136 A JP 11-321079 A JP 2000-094830 A JP-A-5-221640 JP 2000-230107 A JP 2000-002417 A JP 2003-327717 A JP 2003-104725 A JP 2003-261360 A

In the present invention, while maintaining the dispersion stability of fine particles, in particular, high refractive index dispersion characteristics (low Abbe number [νd]), linear characteristics (secondary dispersion [θg, F
In order to improve the diffraction efficiency in the entire visible light region and to prevent a partial drop in the diffraction efficiency in each wavelength region, ITO fine particles are added to the resin.

  However, in any of the above-mentioned patent documents, ITO or the like mixed in a very small amount of fine particles with respect to the resin weight, aggregation occurs at a high concentration of the ITO fine particles, and the optical performance of the present invention It was difficult to obtain a resin composition molded article having a high degree of fine particle dispersibility (low scattering) that can sufficiently satisfy the above.

  Even with dispersion materials such as fine particles prepared by conventional methods, improvement in optical scattering and transmittance can be seen, but they are still inadequate in terms of performance for use in high-performance lenses such as photographing and telephoto lenses. is the current situation. Therefore, there is a demand for a fine particle-dispersed optical material having a high refractive index and a secondary dispersion characteristic that can maintain high transparency and high dispersibility and can be used for excellent film forming and molding applications.

  In view of such a situation, the present invention has good dispersion stability and excellent optical characteristics, that is, high translucency and low optical scattering, and high refractive index and secondary dispersion. An object of the present invention is to provide an optimum ITO fine particle-dispersed optical material capable of forming a molded article exhibiting characteristics, and an optical element using the optical material.

  Accordingly, in order to solve the above-described problems, the present invention provides a fine particle dispersion type optical material having the following configuration, a method for molding an optical element using the optical material, an optical element molded by the molding method, and diffractive optics. Provided are an element, a laminated diffractive optical element, and an optical system having the optical element.

  In the present invention, the ITO fine particles are dispersed in a resin containing at least a photopolymerization initiator, a dispersant, and two or more acrylic groups, methacrylic groups, vinyl groups, or a mixture of these unsaturated ethylene groups. An ultraviolet curable optical material is provided.

  In the present invention, the ITO fine particles have a particle size of 0.050 μm or less, and the ratio to the resin weight is in the range of 15.0 to 75.0% by weight. Provides optical materials.

  In addition, the present invention provides the optical material according to the description, wherein the dispersant is at least one or more belonging to a cationic surfactant such as a quaternary amine salt.

  The present invention also provides an optical element formed from the optical material described above.

  According to another aspect of the present invention, there is provided a method for molding an optical element, wherein the optical element according to any one of the above is used as a molding material for the optical element. providing.

  Further, the present invention is characterized in that when the optical element is molded using the optical material, the optical material is placed in the mold and photopolymerized to mold the optical element. An optical element molding method is provided.

  The present invention also provides a diffractive optical element characterized in that the surface of the optical element described above is a diffractive surface on which a diffractive shape is formed.

  Further, the present invention is configured by combining the diffractive optical element described above and a diffractive optical element having optical characteristics different from the diffractive optical element with the surfaces having mutual diffractive shapes facing each other. A laminated diffractive optical element is provided.

  The present invention also provides a refractive optical element characterized in that the surface of the optical element described above is a refractive surface formed with a refractive shape.

  The present invention also provides an optical system including any one of the optical elements described above.

  The present invention also provides the above-described optical system, wherein the optical system is a projection optical system.

  The present invention also provides the above-described optical system, wherein the optical system is a photographing optical system.

  According to the present invention, at least a photopolymerization initiator, a dispersant, and a resin containing two or more acrylic groups, methacrylic groups, vinyl groups, or a mixture of these unsaturated ethylene groups have a particle size of 0.050 μm or less. An optical material in which ITO fine particles are well dispersed and stabilized can be obtained.

The obtained resin exhibits excellent dispersion stability of the fine particles, that is, extremely low light scattering rate, and high refractive index dispersion property due to the properties of ITO fine particles (small Abbe number [νd]), secondary dispersion. Characteristics ([θg, F
] And an optimum ITO fine particle dispersion type optical material capable of forming a molded body. Therefore, by using this optical material, an optical material having high diffraction efficiency can be provided, a method for molding an optical element using the optical material, an optical element molded by the molding method, and an optical system having the optical element Can be realized.

<Embodiment 1>
In the present invention, a polymer, oligomer, monomer, etc. of acrylic, methacrylic or vinyl or mixed system of these unsaturated ethylene groups in which ITO fine particles are mixed and dispersed in a system using a photopolymerization initiator and a dispersant. By adjusting the resin to be contained, an optical material having a high refractive index high dispersion characteristic and a secondary dispersion characteristic can be provided. By using this optical material as a molding material, an optical element in which chromatic aberration is corrected more accurately can be provided.

  However, in order to use it as a material for an optical element such as a diffractive optical element, it is required not only to have high transparency but also to suppress the occurrence of optical scattering. Further, the same characteristics are required even after the material is cured by ultraviolet rays or the like to form a composition.

  Items that particularly affect the transparency and optical scattering of the fine particles include the size, concentration (addition amount), mixing / dispersing method (dispersibility), and surface characteristics of the fine particles. In the ITO fine particles used in the present invention, the particle size is desirably 0.050 μm or less in order to improve dispersion stability and reduce optical scattering. Furthermore, in order to reduce the attenuation of transmitted light intensity due to Rayleigh scattering, it is particularly preferable to use particles having a particle size of less than about 15 nm. And it is preferable to prepare and disperse | distribute with the narrowest particle size distribution as possible, and as addition concentration, it is desirable that the ratio with respect to resin volume is the range of 15.0-75.0 weight%.

  If the amount of fine particles is too large, it will be difficult to ensure high transmittance due to the coloration of ITO itself. Further, since it becomes difficult to ensure dispersibility due to the multi-order aggregation of the fine particles and the light scattering is remarkably increased, the content is more preferably 60.0% by weight or less. If the amount is too small, the effect of refractive index dispersion characteristics and secondary dispersion characteristics due to ITO cannot be obtained, so the amount of fine particles added is preferably in the range of 35.0 to 50.0% by weight.

  In the present invention, as a method of dispersing the ITO fine particles in the binder resin, a dispersing agent or, if necessary, a dispersion medium can be used. With regard to fine particles and resins that influence the dispersion state, even for substantially the same fine particles and resin, the dispersion state is completely different depending on the type of added dispersant, amount added, molecular weight, polarity, affinity, etc. It is known to show.

  As the dispersant used in the present invention, a pigment derivative, a resin-type dispersant, or an activator-type dispersant can be suitably used. Here, as the dispersant, a cationic, weakly cationic, nonionic or amphoteric surfactant is effective. Especially polyester-based, ε-caprolactone-based, polycarboxylate, polyphosphate, hydrostearate, amide sulfonate, polyacrylate, olefin maleate copolymer, acrylic-maleate copolymer, Alkylamine acetates, alkyl fatty acid salts, fatty acid polyethylene glycol esters, silicons, and fluorines can be used. In the present invention, it is desirable to use at least one base selected from ammonia and organic amines.

  Specifically, in the Dispersic Series (manufactured by Big Chemie Japan), Dispersic 161, 162, 163, and 164 are in the Dispersic Series (manufactured by Genega), and Solsperse 3000, 9000, 17000, 20000, 24000, 41090. In the TAMN series (manufactured by Nikko Chemical Co., Ltd.), there are PO or EO modified products of alkylamines such as TAMN-15. The amount to be added as such a dispersant varies depending on the type of the dispersion solvent, the type of the dispersant, the type of the dispersion resin in which the fine particles are mixed, etc., but is 0.1 to 25 with respect to the weight of the ITO fine particles. It is desirable to be in the range of 0.0% by weight.

  If the amount of the dispersant added is too large, it will cause white turbidity and optical scattering will occur, and the optical properties of the resin obtained by containing fine particles will be unnecessarily lowered. The range of 0 to 18.0% by weight is desirable. Moreover, a dispersing agent can be used only by 1 type, and can also be used in combination of 2 or more types.

  The dispersion resin used in the present invention is not particularly limited, but a resin having high transparency and good compatibility after the ITO fine particles are dispersed is preferable. Examples of suitable resins include acrylic resins, methacrylic resins, vinyl resins, polyester resins, polyamide resins, urethane resins, CAB resins, melamine resins, and epoxy resins. It is not limited to. In the present invention, at least in terms of transparency, compatibility, dispersibility (stability), curability, moldability, durability, etc., the ITO fine particles are made of an acrylic resin, a methacrylic resin, a vinyl resin, or an insoluble resin. It is desirable to disperse in a mixture of saturated ethylene groups. Dispersion resin can be used only by 1 type, and can also be used in combination of 2 or more types.

  Examples of suitable dispersion solvents for use in the present invention include aromatic hydrocarbons such as toluene, benzene and xylene, ethanol, in order to dissolve the binder resin or to preliminarily disperse the ITO fine particles in the solvent. Alcohols such as isopropanol, alicyclic hydrocarbons such as cyclohexane, acetates such as ethyl acetate and butyl acetate, ketones such as acetone and methyl ethyl ketone, amides such as DMF, DMAc and NMP, fats such as hexane and octane Group hydrocarbons, ethyl ethers such as diethyl ether and butyl carbitol, halogenated hydrocarbons such as dichloromethane and carbon tetrachloride, and the like, but are not limited thereto. The organic solvent can be selected in accordance with the affinity of the ITO fine particles to be used, and the organic solvent can be used alone, or two or more organic solvents can be used in combination as long as the dispersibility is not impaired. You can also.

  Moreover, as a photoinitiator in this invention, a radical initiator can be utilized and the radical production | generation mechanism by light irradiation can be utilized, and it becomes a preferable thing for replica shaping | molding of a lens etc. normally. In the dispersion resin, usable photopolymerization initiators include, for example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 1-hydroxy-cyclohexyl-phenyl-ketone, Preferred examples include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4′-diphenylbenzophenone, 4,4′-diphenoxybenzophenone, and the like. be able to.

  The addition ratio of the photopolymerization initiator to the dispersion resin can be appropriately selected according to the amount of light irradiation and further the additional heating temperature, and also according to the target average molecular weight of the polymer to be obtained. Can also be adjusted. When used for the curing and molding of the resin according to the present invention, the addition amount of the photopolymerization initiator is 0. It is preferable to select in the range of 01 to 10.0% by weight.

  Next, an adjustment process of the optical material using the resin, photopolymerization initiator, ITO fine particles, dispersant, and dispersion solvent in the present invention will be described.

  First, the dispersing agent optimized for the selected organic solvent is dissolved, and then ITO fine particles are added and mixed little by little while stirring using a stirrer chip or the like. At that time, the amount of solvent is optimally adjusted while observing the degree of dispersion. If it confirms that it has disperse | distributed suitably, the said resin and a photoinitiator will be gradually added and dissolved, stirring similarly. After confirming complete dissolution, the solvent is removed using an evaporator. At this time, it is desirable to appropriately adjust the degree of vacuum according to the boiling point of the solvent, the amount of residual solvent, and the like. Sudden evaporation and removal of the solvent may deteriorate the degree of aggregation of the fine particles and impair dispersibility.

  In addition, when removing the solvent by reducing the pressure, it is possible to heat to the extent that the dispersibility is not impaired, if necessary. In this way, the optical material of the present invention is obtained. The obtained optical material may contain a residual solvent that has not been completely removed, and depending on the content, it may be considered that the durability and optical characteristics of a later molded product or the like are affected. Therefore, the content of the residual solvent is desirably in the range of 0.01 to 0.50% by weight with respect to the total weight obtained by subtracting the solvent weight. When the degree of vacuum is too high, or when heating is performed simultaneously with the vacuum, or through a vacuum process for a long time, the monomer and the like constituting the dispersant and binder resin added together with the solvent are also distilled off. There is a fear. Therefore, it is necessary to adjust the degree of pressure reduction, temperature, time, etc. in consideration of individual molecular weight, boiling point, sublimation property, and the like.

  In the molding of the diffractive optical element according to the present invention, a process of forming a mold molded body layer from the optical material using such a photopolymerization method is shown. When forming a thin layer structure on a light transmissive material used for a substrate, for example, a glass plate is used for the substrate, while a metal material is used for a mold corresponding to a fine diffraction grating structure. At this time, the mold is formed by pouring the optical material exhibiting fluidity between them and suppressing it lightly. While maintaining this state, the optical material is photopolymerized. The light irradiation used for such a photopolymerization reaction is performed using light of a suitable wavelength, usually ultraviolet light or visible light, corresponding to the mechanism resulting from radical generation using a photopolymerization initiator. For example, the light transmissive material used for the substrate, specifically, a raw material body such as a monomer for preparing an optical material that is molded is uniformly irradiated with light through a glass plate. The amount of light to be irradiated is appropriately selected according to the mechanism resulting from radical generation using the photopolymerization initiator and according to the content ratio of the contained photopolymerization initiator.

  On the other hand, in the production of the molded body layer of the optical material by such a photopolymerization reaction, it is more preferable that the irradiated light is uniformly irradiated to the entire raw material body such as a monomer that is molded. Therefore, it is more preferable to select light having a wavelength that can be uniformly applied through a light-transmitting material used for the substrate, for example, a glass flat plate. In this case, a mode in which the total thickness of the diffraction grating including the molded body of the optical material formed on the light transmissive material used for the substrate is made thinner is more suitable for the present invention. Similarly, it is also possible to produce a molded body layer by a thermal polymerization method. In this case, it is desirable to make the entire temperature more uniform, and the optical material formed on the light-transmitting material used for the substrate is preferably made. A mode in which the total thickness of the diffraction grating including the molded body is reduced is more suitable for the present invention.

  By using the above-described method using the optical material in the present invention, a plurality of layers made of materials having different optical wavelength dispersions are stacked on the substrate, and the diffraction efficiency of a specific order (design order) is increased over the entire use wavelength range. The designed diffractive optical element can be manufactured in a short time. Moreover, you may use 2 or more types of photoinitiators as needed. At the same time, a release agent, a sensitizer, a stabilizer, a thickener and the like may be contained.

  Examples of the present invention will be described below, but the present invention is not limited by them.

  First, the adjustment of the optical material in the present invention will be specifically described.

  Table 1 shows the evaluation results of the dispersion stability and the measurement results of the scattering rate of the optical materials obtained in each experimental example and comparative example. The scattering rate was measured using U-4000 (manufactured by Hitachi, Ltd.). Table 2 shows the optical properties ([nd], [νd], [θg, F]) of the optical materials obtained in each experimental example and comparative example. An Abbe refractometer (manufactured by Kalnew Optical Industry) was used for the measurement.

Disperbyk-180 as a dispersant in xylene solvent
The dispersant-containing xylene solution was adjusted to 1.8 wt% (manufactured by Big Chemie Japan). Subsequently, ITO fine particles having an average particle diameter of 10 nm were added and dispersed so as to have a concentration of 10.0 wt% with respect to the xylene solution obtained above. 30 parts by weight of Aronix M-6200, 18 parts by weight of tris (2-acryloxyethyl) isocyanurate, 18 parts by weight of pentaerythritol triacrylate, 856 parts by weight of the obtained ITO fine particle-containing xylene solution, 34 parts by weight of pentenoxyethyl methacrylate and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IC184) were added and dissolved. Thereafter, the xylene solvent was removed by vacuum suction while heating in an oil bath at about 45 ° C. to prepare the optical material 11. A coating film having a thickness of 10 μm was prepared using the obtained optical material 11. The evaluation and measurement results are shown in Table 1.

  Example 1 was the same as Example 1 except that the xylene solution containing ITO fine particles was changed to 1773 parts by weight. A coating film having a thickness of 10 μm was produced using the optical material 12 thus obtained. The evaluation and measurement results are shown in Table 1.

  A dispersant-containing xylene solution was prepared so that BYK-P104 (manufactured by Big Chemie Japan) as a dispersant in the xylene solvent was 1.8 wt%. Subsequently, ITO fine particles having an average particle diameter of 10 nm were added and dispersed so as to have a concentration of 10.0 wt% with respect to the xylene solution obtained above. 30 parts by weight of Aronix M-6200, 18 parts by weight of tris (2-acryloxyethyl) isocyanurate, 18 parts by weight of pentaerythritol triacrylate, 856 parts by weight of the obtained ITO fine particle-containing xylene solution, 34 parts by weight of pentenoxyethyl methacrylate and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IC184) were added and dissolved. Thereafter, the xylene solvent was removed by suction under reduced pressure while heating in an oil bath at about 45 ° C. to prepare the optical material 13. A coating film having a thickness of 10 μm was prepared using the obtained optical material 13. The evaluation / measurement is shown in Table 1.

Example 3 was the same as Example 3 except that the ITO fine particle-containing xylene solution was changed to 1773 parts by weight. A coating film having a thickness of 10 μm was prepared using the optical material 14 thus obtained. The evaluation and measurement results are shown in Table 1.
[Comparative Example 1]
Disperbyk-108 as a dispersant in xylene solvent
The dispersant-containing xylene solution was adjusted to 1.8 wt% (manufactured by Big Chemie Japan). Subsequently, ITO fine particles having an average particle diameter of 10 nm were added and dispersed so as to have a concentration of 10.0 wt% with respect to the xylene solution obtained above. 30 parts by weight of Aronix M-6200, 18 parts by weight of tris (2-acryloxyethyl) isocyanurate, 18 parts by weight of pentaerythritol triacrylate, 856 parts by weight of the resulting ITO fine particle-containing xylene solution, 34 parts by weight of pentenoxyethyl methacrylate and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IC184) were added and dissolved. Thereafter, the xylene solvent was removed by suction under reduced pressure while heating in an oil bath at about 45 ° C. to prepare the optical material 21. A coating film having a thickness of 10 μm was prepared using the obtained optical material 21. The evaluation and measurement results are shown in Table 1.
[Comparative Example 2]
In Comparative Example 1, the same procedure as in Example 1 was performed except that the xylene solution containing ITO fine particles was changed to 1773 parts by weight. A coating film having a thickness of 10 μm was prepared using the optical material 22 thus obtained. The evaluation and measurement results are shown in Table 1.
[Comparative Example 3]
Disperbyk-112 as a dispersant in xylene solvent
The dispersant-containing xylene solution was adjusted to 1.8 wt% (manufactured by Big Chemie Japan). Subsequently, ITO fine particles having an average particle diameter of 10 nm were added and dispersed so as to have a concentration of 10.0 wt% with respect to the xylene solution obtained above. 30 parts by weight of Aronix M-6200, 18 parts by weight of tris (2-acryloxyethyl) isocyanurate, 18 parts by weight of pentaerythritol triacrylate, and 800 parts by weight of xylene solution containing ITO fine particles were obtained. 34 parts by weight of pentenoxyethyl methacrylate and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IC184) were added and dissolved. Thereafter, the xylene solvent was removed by suction under reduced pressure while heating in an oil bath at about 45 ° C. to prepare the optical material 23. A coating film having a thickness of 10 μm was prepared using the obtained optical material 23. The evaluation and measurement results are shown in Table 1.
[Comparative Example 4]
In Comparative Example 3, the same procedure as in Example 1 was performed except that the xylene solution containing ITO fine particles was changed to 1773 parts by weight. A coating film having a thickness of 10 μm was produced using the optical material 24 thus obtained. The evaluation and measurement results are shown in Table 1.

表１ら分かるように、実施例３，４で調整した分散剤を用いた光学材料１３，１４が最も効果的な分散安定性を示し、散乱率が低い。比較例２で調整した分散剤を用いた光学材料２２は特に分散安定性が悪く、材料調整後、１時間程度で樹脂とＩＴＯ微粒子が完全な分離を生じた。又、各実験例及び比較例で調整した光学材料１１〜１４、２１〜２４は分散剤に拠らずＩＴＯ微粒子の添加量が増加するに連れて粘度が急増した。表１記載の分散剤ごとの散乱率を測定したグラフを図１に示す。

As can be seen from Table 1, the optical materials 13 and 14 using the dispersant prepared in Examples 3 and 4 exhibit the most effective dispersion stability and have a low scattering rate. The optical material 22 using the dispersant prepared in Comparative Example 2 was particularly poor in dispersion stability, and the resin and ITO fine particles were completely separated in about 1 hour after the material was adjusted. Further, the optical materials 11 to 14 and 21 to 24 prepared in each experimental example and comparative example rapidly increased in viscosity as the amount of ITO fine particles added increased without depending on the dispersant. The graph which measured the scattering rate for every dispersing agent of Table 1 is shown in FIG.

  Table 2 shows the optical characteristics of the obtained optical material. The Abbe number νd and secondary dispersion characteristic θg, F of each optical material both show very low values due to the ITO fine particles, and are suitable for the optical element in the present invention. The optical materials obtained in Comparative Examples 2 and 4 had a very high scattering rate due to the dispersibility (aggregation) of the ITO fine particles, so that the refractive index and the like could not be measured.

＜実施の形態２＞
図２及び図３を参照して、本発明における回折光学素子、積層型回折光学素子の構成とその製造方法を説明する。本実施の形態における回折光学素子は４００ｎｍ〜７００ｎｍの波長領域の光束が設計次数に集中するように、回折光学素子４３、回折光学素子４４及び回折光学素子７１の光学樹脂特性に合わせた素子を設計した。

<Embodiment 2>
With reference to FIG.2 and FIG.3, the structure of the diffractive optical element in this invention and a lamination type diffractive optical element and its manufacturing method are demonstrated. The diffractive optical element in the present embodiment is designed to match the optical resin characteristics of the diffractive optical element 43, the diffractive optical element 44, and the diffractive optical element 71 so that the light flux in the wavelength region of 400 nm to 700 nm is concentrated in the design order. did.

As shown in FIG. 2A, the optical material 13 of Example 3 of Embodiment 1 was supplied to a mold 22 processed into a diffraction grating shape. Next, as shown in FIG. 2 (b), a flat glass (BK7) 31 is placed on the optical material 13, the resin is pressurized and stretched to a desired range, and a UV exposure machine (EX250: manufactured by HOYA-SCHOTT).
At 15 J / cm ² (40 mW / cm ² ). Thereafter, as shown in FIG. 2C, the cured product integrated with the glass 31 was released from the mold 33 to manufacture a diffractive optical element 43.

On the other hand, a photocurable resin 61 (RC-C001: manufactured by Dainippon Ink & Chemicals, Inc.) having optical characteristics (nd = 1.523, νd = 51.9) was prepared as another optical material. As shown in FIG. 2A, an optical material 61 was supplied to a mold 35 processed into a diffraction grating shape. Next, as shown in FIG. 2B, a flat glass (BK7) 31 is placed on the optical material 61, the resin is pressurized and stretched to a desired range, and a UV exposure machine (EX250: manufactured by HOYA-SCHOTT). At 30 J / cm ² (40 mW / cm ² ). Thereafter, as shown in FIG. 2C, the cured product integrated with the glass 31 was released from the mold 35 to manufacture a diffractive optical element 71.

  Next, after forming an antireflection film on the diffraction surfaces of the diffractive optical element 43 and the diffractive optical element 71 obtained as described above, as shown in FIG. 3, the diffraction gratings are combined so that their diffraction gratings face each other. An optical element 83 was manufactured. A spacer 32 determines the distance between the diffractive optical element 43 and the diffractive optical element 71. The interstitial pitch of each of the diffractive optical element 43 and the diffractive optical element 71 is 80.00 μm. The distance between the valleys of the diffraction gratings of the diffractive optical element 43 and the diffractive optical element 71 is 24.00 μm, and the distance between the peaks is 1.50 μm. The peak height of the diffractive optical element 43 is 10.31 μm, and the peak height of the diffractive optical element 71 is 12.19 μm.

As shown in FIG. 2A, the optical material 14 of Example 4 of Embodiment 1 was supplied to a mold 34 processed into a diffraction grating shape. Next, as shown in FIG. 2B, a flat glass (BK7) 31 is placed on the optical material 14, the resin is pressurized and stretched to a desired range, and a UV exposure machine (EX250: manufactured by HOYA-SCHOTT).
At 15 J / cm ² (40 mW / cm ² ). Thereafter, as shown in FIG. 2C, the cured product integrated with the glass 31 was released from the mold 34 to manufacture a diffractive optical element 44.

On the other hand, a photocurable resin 61 (RC-C001: manufactured by Dainippon Ink & Chemicals, Inc.) having optical characteristics (nd = 1.523, νd = 51.9) was prepared as another optical material. As shown in FIG. 2A, an optical material 61 was supplied to a mold 36 processed into a diffraction grating shape. Next, as shown in FIG. 2B, a flat glass (BK7) 31 is placed on the optical material 61, the resin is pressurized and stretched to a desired range, and a UV exposure machine (EX250: manufactured by HOYA-SCHOTT). At 30 J / cm ² (40 mW / cm ² ). Thereafter, as shown in FIG. 2C, the cured product integrated with the glass 31 was released from the mold 36 to manufacture a diffractive optical element 72.

  Next, an antireflection film is formed on the diffraction surfaces of the diffractive optical element 44 and the diffractive optical element 72 obtained above, and then combined so that the diffraction gratings face each other as shown in FIG. An optical element 84 was manufactured. A spacer 32 determines the distance between the diffractive optical element 44 and the diffractive optical element 72. The interstitial pitch of each of the diffractive optical element 44 and the diffractive optical element 72 is 80.0 μm. The distance between the valleys of the diffraction gratings of the diffractive optical element 44 and the diffractive optical element 72 is 19.73 μm, and the distance between the peaks is 1.50 μm. The peak height of the diffractive optical element 44 is 8.06 μm, and the peak height of the diffractive optical element 72 is 10.17 μm.

  Intensity at each wavelength (400 nm to 700 nm) of primary diffracted light with an incident angle of 0 ° in the laminated diffractive optical elements 83 and 84 manufactured in Examples 1 and 2 is shown in FIGS. 4-1 and 4-2, respectively. It was. The horizontal axis indicates the wavelength, and the vertical axis indicates the diffraction efficiency. In general, it can be said that the diffraction efficiency of a laminated diffractive optical element is good if it is 99% or more. Therefore, the quality judgment in this experiment was determined by whether the diffraction efficiency was 99% or more over the entire visible region of 400 nm to 700 nm.

  4-1 and 4-2, the diffraction efficiencies at a wavelength of 400 nm are 99.7% and 99.9%, and the diffraction efficiencies at a wavelength of 500 nm are 100.0%, 100.0%, and a wavelength of 600 nm. In this case, the diffraction efficiency is 99.5% and 100.0%, and the diffraction efficiency at a wavelength of 700 nm is 99.2% and 100.0%.

  The diffraction efficiency of the laminated diffractive optical element 83 produced using the optical material 13 and the optical material 61 according to Example 1 has a strength of 99% or more over the entire operating wavelength range, and is relatively good and stable. The result of wavelength distribution is shown. Similarly, the diffraction efficiency of the laminated diffractive optical element 84 manufactured using the optical material 14 and the optical material 61 according to Example 2 is 99% or more over the entire operating wavelength range, and has a very good strength. It can be said that the wavelength distribution is shown.

  From Table 2 describing the measurement results of the optical characteristics and the diffraction efficiency results, and FIGS. 4A and 4B, as the content of the ITO fine particles increases, the secondary dispersion characteristics [θg, It can be seen that F] is low and the diffraction efficiency is high. In addition, there is little occurrence of a drop in diffraction efficiency due to wavelength. Similarly, the Abbe number [νd] tends to decrease due to the content of ITO fine particles. Accordingly, the grating height of the diffractive optical element can be designed to be low, and flare due to the influence of the grating side surface can be reduced.

  According to the present invention, at least a photopolymerization initiator, a cationic surfactant (dispersing agent) such as a quaternary amine salt, and a mixture of two or more acrylic groups, methacrylic groups or vinyl groups, or unsaturated ethylene groups thereof. An optical material in which ITO fine particles having a particle size of 0.050 μm or less are well dispersed and stabilized in the resin contained can be obtained. In addition, the obtained resin exhibits high translucency and excellent dispersion stability of fine particles, that is, low light scattering, and refractive index dispersion characteristics (Abbe number [νd]) due to the properties of ITO fine particles, secondary dispersion The characteristic ([θg, F]) is exhibited, and thus an optimum ITO fine particle dispersed optical material capable of forming a molded body can be provided. Therefore, by using this optical material in consideration of the relationship between the refractive index, Abbe number, and second-order dispersion characteristics, there is no partial drop in diffraction efficiency due to wavelength, and the diffraction efficiency of each used wavelength region in the entire visible region. Can provide a stable optical element. At the same time, by using a laminated diffractive optical element, it is possible to provide an optical element in which chromatic aberration is corrected more accurately.

It is a graph which shows the scattering rate of the optical material in Example 1, 3 of this invention, and Comparative Examples 1 and 3. FIG. It is sectional drawing which shows the shaping | molding process of the diffractive optical element in Example 1, 2 of this invention. It is sectional drawing which shows the structure of the laminated | stacked diffractive optical element in Example 1, 2 of this invention. It is a graph which shows the 1st-order diffracted light intensity of the lamination type diffractive optical element in Example 1 of this invention. It is a graph which shows the 1st-order diffracted light intensity of the lamination type diffractive optical element in Example 2 of this invention.

Explanation of symbols

11-14, 21-21, 61 Optical material 31 Flat glass 32 Spacer 33-36 Mold 43, 44, 71 Diffractive optical element 83, 84 Laminated diffractive optical element

Claims (12)

  An ultraviolet curable type in which ITO fine particles are dispersed in a resin containing at least a photopolymerization initiator, a dispersant, and two or more acrylic groups, methacrylic groups, vinyl groups, or a mixture of these unsaturated ethylene groups. Optical material.   2. The optical material according to claim 1, wherein a particle diameter of the ITO fine particles is 0.050 μm or less, and a ratio to the resin weight is in a range of 15.0 to 75.0% by weight.   The optical material according to claim 1, wherein the dispersant is at least one or more belonging to a cationic surfactant such as a quaternary amine salt.   An optical element formed from the optical material according to claim 1. In the method of molding an optical element, which molds the optical element with a mold,
A method for molding an optical element, wherein the optical material according to claim 1 is used as a molding material for the optical element.   6. The method of molding an optical element according to claim 5, wherein when the optical element is molded using the optical material, the optical element is molded by placing the optical material on the mold and performing photopolymerization. .   7. The diffractive optical element according to claim 3, wherein the surface of the optical element is a diffractive surface on which a diffractive shape is formed.   A laminated type comprising: the diffractive optical element according to claim 7; and a diffractive optical element having optical characteristics different from those of the diffractive optical element, with the surfaces having mutual diffractive shapes facing each other. Diffractive optical element.   7. The refractive optical element according to claim 3, wherein the surface of the optical element is a refractive surface on which a refractive shape is formed.   An optical system comprising the optical element according to claim 3.   The optical system according to claim 10, wherein the optical system is a projection optical system.   The optical system according to claim 10, wherein the optical system is a photographing optical system.

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