JP2007093893A - Optical component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical component comprising a material composition which has excellent transparency and high refractive index by uniformly dispersing fine particles into a resin matrix. <P>SOLUTION: The optical component comprises the material composition constituted by dispersing inorganic fine particles into the resin having a refractive index larger than 1.60. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical component comprising a material composition excellent in high refraction, transparency and light weight (for example, spectacle lens, lens for optical device, lens for optoelectronics, lens for laser, lens for pickup, In-vehicle camera lens, portable camera lens, digital camera lens, OHP lens, and the like.

  In recent years, research on optical materials has been actively conducted, and particularly in the field of lens materials, materials that are excellent in high refraction, heat resistance, transparency, easy moldability, light weight, chemical resistance, solvent resistance, etc. Development of is strongly desired.

Plastic lenses are lighter and harder to break than inorganic materials such as glass and can be processed into various shapes, so in recent years they are rapidly spreading not only to spectacle lenses but also to optical materials such as portable camera lenses and pickup lenses. .
Along with this, it has been required to increase the refractive index of the material itself in order to reduce the thickness of the lens. For example, a technique for introducing a sulfur atom into a polymer (see Patent Document 1 and Patent Document 2) In addition, a technique for introducing a halogen atom or an aromatic ring into a polymer (Patent Document 3) has been actively studied. However, a plastic material that has a refractive index higher than 1.80 and has good transparency and can be used as a substitute for glass has not yet been developed.

  Since it is difficult to increase the refractive index with only an organic substance, a method for producing a high refractive index material by dispersing an inorganic substance having a high refractive index in a resin matrix has been reported (see Patent Document 4). In order to reduce attenuation of transmitted light due to Rayleigh scattering, it is preferable to uniformly disperse inorganic fine particles having a particle size of 15 nm or less in the resin matrix. However, since primary particles having a particle size of 15 nm or less are very likely to aggregate, it is extremely difficult to uniformly disperse them in the resin matrix. In addition, when the attenuation of transmitted light in the optical path length corresponding to the thickness of the lens is taken into consideration, the amount of inorganic fine particles added must be limited. For this reason, by dispersing fine particles in a resin matrix, it has not been possible to produce a material that achieves both high refraction (over 1.80) and high transparency.

JP 2002-131502 A Japanese Patent Laid-Open No. 10-298287 JP 2004-244444 A JP 2003-73564 A

Therefore, a plastic material having both high refractive index (refractive index> 1.80), transparency, and light weight, and an optical component such as a lens including the plastic material have not yet been found, It was desired.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical material comprising a material composition in which fine particles are uniformly dispersed in a resin matrix and has excellent transparency and a high refractive index. To provide parts.

  As a result of intensive studies to achieve the above object, the present inventors have made a material using a specific resin having a high refractive index and excellent transparency and inorganic fine particles compatible with the resin matrix as raw materials. The composition was found to have high refraction and excellent transparency due to the effect of uniform dispersion of fine particles, and the present invention was completed.

That is, the present invention is specified in the items described in [1] to [5] below.
[1] An optical component comprising a material composition in which inorganic fine particles are dispersed in a resin having a refractive index of greater than 1.60.
[2] An optical component comprising a material composition in which inorganic fine particles are dispersed in a resin having a refractive index of greater than 1.65.
[3] The optical component according to [1] or [2], wherein the refractive index of the material composition is greater than 1.80.
[4] The optical component according to any one of [1] to [3], wherein the number average particle size of the inorganic fine particles is 1 to 15 nm and the refractive index is 1.90 to 3.00.
[5] The optical component according to any one of [1] to [4], wherein the optical component has a light transmittance in terms of 1 mm thickness at a wavelength of 589 nm of 80% or more.
[6] The optical component according to any one of [1] to [5], wherein the optical component is a lens.

  The optical component of the present invention includes a material composition in which fine particles are uniformly dispersed in a resin matrix and has excellent transparency and a high refractive index. Further, according to the present invention, it is easy to provide an optical component having good mechanical strength and heat resistance.

  Hereinafter, the optical component of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[resin]
The material composition in the present invention is a composition in which inorganic fine particles described later are dispersed in a resin having a high refractive index. Even if inorganic fine particles having a particle size sufficiently smaller than the wavelength of light are used, transmitted light is attenuated by Rayleigh scattering. For this reason, in the conventional method, since the transmitted light is not greatly attenuated, the inorganic component in the material composition cannot be increased. However, in the present invention, not only inorganic fine particles having a small particle size but also a specific resin having a high refractive index as a matrix is used to suppress scattering at the interface between the inorganic fine particles and the resin. We succeeded in obtaining material compositions exceeding 80.

  In order to suppress scattering and obtain a material having a refractive index greater than 1.80, the present invention uses a resin having a refractive index greater than 1.60. The refractive index of the resin is preferably greater than 1.65, more preferably greater than 1.67, and particularly preferably greater than 1.69. In addition, the refractive index in this invention is the value measured about the light of wavelength 589nm with the Abbe refractometer (Atago Co., Ltd. DR-M4).

  The resin used in the present invention preferably has a glass transition temperature of 80 ° C to 400 ° C, and more preferably 130 ° C to 380 ° C. If a resin having a glass transition temperature of 80 ° C. or higher is used, an optical component having sufficient heat resistance can be easily obtained, and if a resin having a glass transition temperature of 400 ° C. or lower is used, molding tends to be easily performed.

  The resin used in the present invention preferably has a light transmittance at a wavelength of 589 nm of 80% or more, and more preferably 85% or more.

  Although the preferable specific example of resin which can be used by this invention is given to the following, resin which can be used by this invention is not limited to these. The repeating units x and y represent the copolymerization ratio (mol ratio).

In the present invention, a thermoplastic and thermosetting resin containing sulfur may be used as the resin. Examples of monomers and polymers having a dithian structure include those described in JP-A-5-148340, JP-A-6-192250, JP-A-11-202101, JP-A-2002-131502, and the like. Examples of the monomer having an episulfide structure and examples of the cured resin include those described in JP-A Nos. 9-110979, 9-255781, and 10-298287. Examples of the resin having a urethane structure include those described in JP-A-5-208950, JP-A-7-252207, JP-A-2001-342252, and the like. Examples of the resin having a phenylene sulfide structure include those described in JP-A-7-316295, JP-A-8-92367, JP-A-8-104751, and JP-A-8-100065.
Examples of other resins having a refractive index of 1.65 or more include those described in JP-A Nos. 5-178929 and 7-267919.

  These resins may be used alone or in combination of two or more. When two or more types are mixed and used, it is necessary that the resin mixture after mixing satisfies the above refractive index condition.

[Inorganic fine particles]
Examples of the inorganic fine particles used in the present invention include oxide fine particles, sulfide fine particles, selenide fine particles, telluride fine particles and the like. More specifically, examples include titanium oxide fine particles, zinc oxide fine particles, zirconium oxide, tin oxide, and zinc sulfide fine particles, but are not limited thereto. In the present invention, one type of inorganic fine particles may be used alone, or a plurality of types of inorganic fine particles may be used in combination.

The method for producing inorganic fine particles used in the present invention is not particularly limited, and any known method can be used. Desired oxide fine particles can be obtained by using a metal halide or alkoxy metal as a raw material and hydrolyzing in a reaction system containing water.
For example, titanyl sulfate is exemplified for the synthesis of titanium oxide nanoparticles, and zinc salts such as zinc acetate and zinc nitrate are exemplified for the synthesis of zinc oxide nanoparticles. Metal alkoxides such as tetraethoxysilane and titanium tetraisopropoxide can also be suitably used as raw materials. For example, a known method described in Japanese Journal of Applied Physics, 37, 4603-4608 or (1998) Langmuir, 16: 1 241-246 (2000) can be used. In particular, when oxide nanoparticles are synthesized by a sol formation method, for example, titanium oxide nanoparticles using titanyl sulfate as a raw material are synthesized and then dehydrated with an acid or alkali via a precursor such as hydroxide. Procedures that condense or peptize to form a hydrosol are also possible. In the procedure via such a precursor, it is preferable from the viewpoint of the purity of the final product that the precursor is isolated and purified by any method such as filtration or centrifugation. An appropriate surfactant such as sodium dodecylbenzenesulfonate (abbreviated as DBS) or dialkylsulfosuccinate monosodium salt (manufactured by Sanyo Chemical Industries, Ltd., trade name is Eleminol JS-2) is added to the hydrosol to obtain a sol The particles may be isolated by making them water-insoluble. For example, a known method described in Coloring Materials, Vol. 57, No. 6, 305-308 (1984) can be used.

In addition to the method of hydrolyzing in water, the inorganic fine particles may be prepared in an organic solvent or an organic solvent in which the resin used in the present invention is dissolved.
Examples of the solvent used in these methods include acetone, 2-butanone, dichloromethane, chloroform, toluene, ethyl acetate, cyclohexanone, anisole and the like. These may be used alone or as a mixture of two or more.

  If the number average particle size of the inorganic fine particles used in the present invention is too small, the characteristics unique to the substance constituting the fine particles may change. Conversely, if the number average particle size is too large, the effect of Rayleigh scattering becomes significant. The transparency of the material composition may be extremely lowered. Therefore, the lower limit value of the number average particle size of the inorganic fine particles used in the present invention is preferably 1 nm, more preferably 2 nm, still more preferably 3 nm, and the upper limit value is preferably 15 nm, more preferably 10 nm, still more preferably 5 nm. It is.

  The range of the refractive index of the inorganic fine particles used in the present invention is preferably 1.90 to 3.00, more preferably 1.90 to 2.70, and 2.00 to 2.70. Is more preferable. If inorganic fine particles having a refractive index of 1.90 or more are used, a material composition having a refractive index greater than 1.80 can be easily produced. If inorganic fine particles having a refractive index of 3.00 or less are used, the transmittance is 80% or more. It tends to be easy to create a material composition.

[Dispersant]
The fine particles used in the present invention are preferably dispersed in the resin using a dispersant. The molecular weight of the dispersant used in the present invention is usually 50 to 10,000, more preferably 100 to 5,000, and still more preferably 200 to 1,000. If the molecular weight is too large, it tends to be difficult to increase the refractive index of the material composition.

  When the fine particles used in the present invention are coordinated or modified with an organic compound (referred to as “dispersant” in the present invention) having compatibility with the resin matrix mainly composed of the resin, the fine particles on the resin matrix Dispersibility may be improved, and transparency and mechanical strength of the material composition of the present invention may be improved. The effect of the dispersant is considered to be due to a combination of the effect of suppressing aggregation of fine particles and the effect of improving the compatibility with the resin matrix.

A preferred structure of such a dispersant is represented by the following general formula (1).
General formula (1)
A-R
However, A represents the functional group which can form arbitrary chemical bonds with the surface of microparticles | fine-particles, and R represents a C1-C30 monovalent group or polymer which has compatibility or reactivity with a resin matrix. The chemical bond is, for example, a covalent bond, an ionic bond, a coordination bond, a hydrogen bond, etc.

  Although there is no limitation on the method of coordination of the dispersant to the inorganic fine particles and the modification method by covalent bonding and the molecular structure of the organic substance used therefor, specific examples of A coordinated on the fine particles include thiol and sulfonic acids. A sulfur-containing organic compound, a phosphorus-containing organic ligand having phosphine or phosphine oxide, a nitrogen-containing ligand having an alkylamine or an aromatic amine, or a ligand having a carboxylic acid is effective. Among these examples, a phosphorus-containing organic ligand is preferably used, and for example, KAYAMER PM-21 manufactured by Nippon Kayaku is suitable.

  Specific examples of A modified by covalent bonding include silane coupling agents, titanate coupling agents, aluminum coupling agents and the like conventionally used for surface treatment of oxides such as silica, alumina, and titania. A metal alkoxide group which is an active functional group is effective. Among these, a silane coupling agent is preferable, and methods described in JP-A-5-221640, JP-A-9-100111, JP-A-2002-187721, and the like can be used.

On the other hand, when R is a group having compatibility or reactivity with the resin matrix, the chemical structure thereof is the same as or similar to part or all of the chemical structure of the resin that is the main component of the resin matrix. Is preferred.
These dispersants may be used alone or in combination of two or more.

（式中、Ｂ¹ およびＢ² は炭素数６〜１８のアルキル基またはアリールアルキル基、ｍは０または１、Ｘは

のうちのいずれかであり、Ｒ¹ およびＲ² は水素原子または炭素数４以下のアルキル基を示す。） [Plasticizer]
If the glass transition temperature of the resin is high, molding may not always be easy. For this reason, a plasticizer may be used to lower the molding temperature. As a plasticizer used by this invention, what has a structure represented by General formula (2) is preferable.
General formula (2)

(Wherein B ¹ and B ² are alkyl or arylalkyl groups having 6 to 18 carbon atoms, m is 0 or 1, and X is

R ¹ and R ^{2 each} represent a hydrogen atom or an alkyl group having 4 or less carbon atoms. )

In the compound represented by the general formula (2), B ¹ and B ² may be any alkyl group or arylalkyl group within the range of 6 to 18 carbon atoms. If the number of carbon atoms is less than 6, the molecular weight may be too low to boil at the melting temperature of the polymer and generate bubbles. On the other hand, when the number of carbon atoms exceeds 18, the compatibility with the polymer is deteriorated, so that the effect of addition is insufficient.
Specific examples of the groups B ¹ and B ² include n-hexyl group, n-octyl group, n-decyl group, n-dodecyl group, n-tetradecyl group, n-hexadecyl group, n-octadecyl group and the like. Straight alkyl groups, branched alkyl groups such as 2-hexyldecyl group and methyl-branched octadecyl group, and arylalkyl groups such as benzyl group and 2-phenylethyl group. Specific examples of the compound represented by the general formula (2) used in the present invention include the following compounds, among which W-1 (trade name [KP-L155] manufactured by Kao Corporation) is preferable.

[Material composition]
The material composition in the present invention is a composition in which inorganic fine particles are dispersed in a resin having a high refractive index. The method for preparing the material composition is not particularly limited. Specifically, a method of individually synthesizing a resin and inorganic fine particles and mixing them, a method of synthesizing a resin in the presence of pre-synthesized inorganic fine particles, and a method of synthesizing inorganic fine particles in the presence of a pre-synthesized resin Examples thereof include a method, a method of simultaneously synthesizing both a resin and inorganic fine particles, and any of these methods may be used.

  For example, when adopting a method in which a resin and inorganic fine particles are separately synthesized and mixed together, the inorganic fine particles and the resin solution may be stirred and mixed, or the inorganic fine particle dispersion and the resin solution may be stirred and mixed. May be. At this time, the inorganic fine particles or the dispersion thereof may be mixed with the resin solution all at once, or may be gradually dropped into the resin solution. Further, a plasticizer or a dispersant may be present during the stirring and mixing. Such a plasticizer or dispersant may be added in advance to the resin solution or the inorganic fine particle dispersion, or may be added to a mixture of the resin solution and the inorganic fine particles.

  The material composition obtained in the present invention preferably has a light transmittance at a wavelength of 589 nm of 80% or more, and more preferably 90% or more. If the light transmittance at a wavelength of 589 nm is 80% or more, it is easy to obtain an optical component such as a lens having more preferable properties. The light transmittance in the present invention is a value measured with a UV-visible absorption spectrum measuring apparatus UV-3100 (Shimadzu Corporation) after molding a resin to prepare a substrate having a thickness of 1.0 mm.

  The material composition used in the present invention preferably has a glass transition temperature of 100 ° C to 400 ° C, more preferably 130 ° C to 380 ° C. When the glass transition temperature is 100 ° C. or higher, sufficient heat resistance is easily obtained, and when the glass transition temperature is 400 ° C. or lower, molding processing tends to be easily performed.

[Optical parts]
The material composition described above is a material composition that has both high refractive properties, light transmittance, and light weight and excellent optical properties. The refractive index of the material composition can be arbitrarily adjusted. The optical component of the present invention contains the material composition described above. The kind of the optical component of the present invention is not particularly limited. In particular, it is suitably used for an optical component utilizing the excellent optical properties of the material composition, particularly an optical component that transmits light (so-called passive optical component). Functional devices including such optical components include various display devices (liquid crystal display, plasma display, etc.), various projector devices (OHP, liquid crystal projector, etc.), optical fiber communication devices (optical waveguide, optical amplifier, etc.), cameras, videos, etc. The imaging device is exemplified.

  Examples of the passive optical component in such an optical functional device include a lens, a prism, a panel (plate-shaped molded body), a film, an optical waveguide (film-like or fiber-like), an optical disk, and the like. Of these exemplified optical components, the optical component of the present invention can be particularly preferably used as a lens. For such passive optical components, an optional coating layer, for example, a protective layer that prevents mechanical damage to the coated surface due to friction and wear, light rays with an undesirable wavelength that causes deterioration of inorganic particles and substrates, etc. A light absorbing layer that absorbs light, a transmission shielding layer that suppresses or prevents the transmission of reactive low molecules such as moisture and oxygen gas, an antiglare layer, an antireflection layer, a low refractive index layer, etc. A multilayer structure may be used. Specific examples of such an optional coating layer include a transparent conductive film and gas barrier film made of an inorganic oxide coating layer, a gas barrier film made of an organic coating layer, a hard coat, and the like. A known coating method such as a sputtering method, a dip coating method, or a spin coating method can be used.

  The features of the present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Analysis and Evaluation Method]
(1) X-ray diffraction (XRD) spectrum measurement It measured at 23 degreeC using Rigaku Co., Ltd. RINT1500 (X-ray source: Copper K alpha ray, wavelength 1.5418?).
(2) Observation with Transmission Electron Microscope (TEM) It was carried out with an H-9000UHR transmission electron microscope (acceleration voltage 200 kV, degree of vacuum at the time of observation of about 7.6 × 10 ⁻⁹ Pa) manufactured by Hitachi, Ltd. .
(3) Measurement of light transmittance A resin to be measured was molded to prepare a substrate having a thickness of 1.0 mm, and measurement was performed with a UV-visible absorption spectrum measuring apparatus UV-3100 (manufactured by Shimadzu Corporation).
(4) Refractive index measurement Light having a wavelength of 589 nm was measured with an Abbe refractometer (DR-M4 manufactured by Atago Co., Ltd.).

[Synthesis of materials]
(1) Synthesis of Titanium Oxide Nanoparticles While stirring 0.1 mol / L titanyl sulfate aqueous solution, 1.5 mol / L sodium carbonate aqueous solution of the same volume was added dropwise at room temperature over 10 minutes. The white ultrafine particle suspension thus obtained was centrifuged at 3500 rpm and purified by repeating the steps of removing the supernatant by decantation and washing with water. The white precipitate thus obtained was heated at 50 ° C. for about 1 hour with stirring and dispersing in 0.3 mol / L of dilute hydrochloric acid to obtain a transparent acidic hydrosol. This acidic hydrosol was ice-cooled, and an aqueous solution of sodium dodecylbenzenesulfonate was added to form a white precipitate, which was then extracted with toluene, dried and concentrated. From the XRD and TEM of the concentrated residue, it was confirmed that anatase-type titanium oxide fine particles (number average particle size was about 5 nm) were formed.

(2) Synthesis of Exemplary Compound P-1 BPFL (trade name; manufactured by JFE Chemical Co., Ltd.) 4.51 g, hydrosulfite sodium 43 mg, tetrabutylammonium chloride 199 mg, 2 mol / L sodium hydroxide aqueous solution 15 ml, dichloromethane 27 ml And 57 ml of water were put into a 300 ml three-necked flask equipped with a stirrer and stirred in a water bath at 300 rpm in a nitrogen stream. After 15 minutes, a solution obtained by suspending 1.63 g of 2,6-naphthalenedicarboxylic acid chloride and 1.31 g of isophthalic acid chloride in 40 ml of dichloromethane was added. After stirring for 3 hours, 1.5 L of dichloromethane, 71 ml of 0.1 mol / L hydrochloric acid aqueous solution and 500 ml of water were added, and the organic layer was separated. The obtained organic layer was concentrated to 200 ml under reduced pressure, and then poured into 1 L of methanol that was vigorously stirred. The precipitated white precipitate was collected by filtration, washed with 1 L of methanol, heated and dried at 40 ° C. for 12 hours, and then dried at 70 ° C. for 3 hours under reduced pressure to obtain 7.1 g of Exemplified Compound P-1.
As a result of measuring the molecular weight of the obtained P-1 by GPC (tetrahydrofuran solvent; polystyrene conversion (HLC-8120GPC manufactured by Tosoh Corporation)), the weight average molecular weight was 41,000. The glass transition temperature was 270 ° C., and the 5% mass reduction temperature was 440 ° C.

(3) Others Exemplified compounds P-11 and P-15 and polymethyl methacrylate (PMMA) were purchased from ALDRICH. The weight average molecular weight of these resins is 1100000 for P-11, 175000 for P-15, and 120,000 for polymethyl methacrylate. Moreover, the glass transition temperature of these resin is 200 degreeC for P-11, 135 degreeC for P-15, and 114 degreeC for polymethylmethacrylate.

[Manufacture of optical components by thermoforming]
The lenses of Examples 1 to 3 and Comparative Examples 1 to 6 were manufactured by the following procedure. The type of resin used in the following procedure and the amount of titanium oxide nanoparticles used were as shown in Table 1. However, in Comparative Examples 1 to 4, only the resin was molded without adding titanium oxide and a plasticizer.
Titanium oxide nanoparticles dispersed in toluene were added dropwise to the resin anisole solution over 5 minutes, and the mixture was stirred for 1 hour. In the solution, 10% by mass of plasticizer W-1 was added to the resin and stirred, and then the solvent was removed. The obtained material composition was heat-molded at 220 ° C. to prepare a lens molded body having a thickness of 1 mm. The molded body was cut and the cross section was observed with a TEM to confirm whether the inorganic fine particles were uniformly dispersed in the resin. Further, light transmittance measurement and refractive index measurement were performed. These results are listed in Table 1 below. Thereafter, the lens molding was molded into a lens shape to obtain a lens as an optical component.

  As is apparent from Table 1, optical components having a refractive index greater than 1.80 and good transparency were obtained according to the present invention (Examples 1 to 3). When polymethyl methacrylate (PMMA) having a low refractive index was used, no optical component having a high refractive index was obtained (Comparative Examples 5 and 6). Among these comparative examples, the molded body of 21% by mass of titanium oxide (Comparative Example 5) had good transparency, but the molded body of 43% by mass (Comparative Example 6) could not ignore the influence of Rayleigh scattering. The decrease in transmittance was remarkable.

  The optical component of the present invention includes a material composition having both high refractive properties, light transmittance and light weight. ADVANTAGE OF THE INVENTION According to this invention, the optical component which adjusted the refractive index arbitrarily can be provided comparatively easily. In addition, it is easy to provide optical components with good mechanical strength and heat resistance. Therefore, the present invention is useful for providing a wide range of optical components such as a high refractive lens, and has high industrial applicability.

Claims (6)

  An optical component comprising a material composition in which inorganic fine particles are dispersed in a resin having a refractive index of greater than 1.60.   An optical component comprising a material composition in which inorganic fine particles are dispersed in a resin having a refractive index of greater than 1.65.   The optical component according to claim 1, wherein the refractive index of the material composition is greater than 1.80.   4. The optical component according to claim 1, wherein the inorganic fine particles have a number average particle size of 1 to 15 nm and a refractive index of 1.90 to 3.00.   The optical component according to any one of claims 1 to 4, wherein the optical component has a light transmittance of 80% or more in terms of a thickness of 1 mm at a wavelength of 589 nm.   The optical component according to claim 1, wherein the optical component is a lens.