JP2007197606A - Resin material for optics, optical element, and method for producing resin material for optics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element having a thermally stable refractive index while keeping a constant water content, and excellent blue light transmissivity. <P>SOLUTION: An object lens 7 as the optical element is obtained by molding a resin material for the optics, containing a thermoplastic resin and hydrophobic oxide particles. The hydrophobic oxide particle is obtained by subjecting a homogeneous oxide particle in which silicon oxide and one or more kinds of oxides of metals except the silicon are homogeneously dispersed to hydrophobizing treatment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, and the like, and particularly relates to an optical resin material that is thermally stable and excellent in blue light transmittance and an optical element using the same.

  Information devices such as a player, a recorder, and a drive for reading and recording information on an optical information recording medium such as MO, CD, and DVD are provided with an optical pickup device. The optical pickup device includes an optical element unit that receives light reflected from an optical information recording medium by irradiating light of a predetermined wavelength emitted from a light source with a light receiving element, and the optical element unit transmits the light to optical information. It has an optical element such as a lens for condensing light by a reflective layer of a recording medium or a light receiving element.

The optical element of the optical pickup device is preferably made of plastic as a material in that it can be manufactured at low cost by means such as injection molding. As plastics applicable to optical elements, copolymers of cyclic olefins and α-olefins are known (see Patent Documents 1 to 5). In recent years, when using an optical pickup device, studies have been made to use blue light (wavelength near 405 nm) to improve recording density. In an optical element unit such as a pickup, thermal and optical stability It is requested | required to comprise with the substance which has this.
JP 2002-207101 A JP 2002-241560 A Japanese Patent Laid-Open No. 2002-241692 Japanese Patent Application Laid-Open No. 2002-241592 JP 2002-241612 A

  However, materials such as plastics that have large physical property fluctuations due to heat, when used in optical pickup devices that use blue light, ensure stable optical performance due to aberrations caused by refractive index changes due to temperature changes. It can be difficult. Even in the case of a resin used for an optical element of an optical pickup device, such as the above-mentioned copolymer of cyclic olefin and α-olefin, the present situation is that the suppression of aberration due to temperature change is not sufficient.

  Furthermore, due to an increase in the output of a laser light source used in an optical pickup device in recent years and an increase in environmental temperature change caused by drive heat generated from a drive device for optical elements, the problem of generation of aberration due to temperature change is becoming obvious. For this reason, attempts have been made to reduce refractive index change due to temperature change by combining resin with an inorganic substance. Silica fine particles may be used as an inorganic substance that can reduce the refractive index change due to the temperature change of the resin. However, when an inorganic material is combined with a resin having a very low water absorption, such as a cyclic olefin, the water absorption rate of the composite material increases, and stable optical performance may not be obtained. there were. Therefore, as with the composite materials proposed so far, simply combining a thermoplastic resin with a simple inorganic material has made it difficult to say that the composite material is practical because of its hygroscopicity. .

  An object of the present invention is an optical resin material suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, etc., which has a constant refractive index and is thermally stable while maintaining a constant moisture content. It is an object to provide an optical resin material and an optical element that are excellent in transparency. Another object of the present invention is to provide a method for producing the optical resin material.

As a first aspect of the present invention for solving the above problems,
An optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
The hydrophobic oxide particles are particles obtained by subjecting uniform oxide particles in which silicon oxide and one or more kinds of metal oxides other than silicon are uniformly distributed to a hydrophobic treatment. Yes.

In the optical resin material according to the first embodiment of the present invention,
The hydrophobizing treatment is preferably a treatment in which silazanes are attached to the surface of the uniform oxide particles and heated, and the silazanes are preferably hexamethyldisilazane.

In the optical resin material according to the first embodiment of the present invention,
The surface of the hydrophobic oxide particles is preferably formed of polysilazane.

In the optical resin material according to the first embodiment of the present invention,
The hydrophobic oxide particles preferably have a particle size of 1 to 50 nm.

As a second aspect of the present invention,
An optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
The hydrophobic oxide particles are subjected to a hydrophobic treatment on uniform oxide particles in which silicon oxide and one or more kinds of metal oxides other than silicon are uniformly distributed and a silica layer is formed on the surface. It is characterized by being particles.

In the optical resin material according to the second aspect of the present invention,
The silica layer is preferably formed of tetramethoxysilane or tetraethoxysilane.

In the optical resin material according to the second aspect of the present invention,
The hydrophobizing treatment is preferably a treatment in which silazanes are attached to the surface of the silica layer and heated, and the silazanes are preferably hexamethyldisilazane.

In the optical resin material according to the second aspect of the present invention,
The surface of the hydrophobic oxide particles is preferably formed of polysilazane.

In the optical resin material according to the second aspect of the present invention,
The hydrophobic oxide particles preferably have a particle size of 1 to 50 nm.

As a third aspect of the present invention,
An optical element characterized by being molded using the optical resin material according to the first and second embodiments of the present invention.

As the fourth aspect of the present invention,
A method for producing an optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
A particle forming step of uniformly distributing silicon oxide and one or more kinds of metal oxides other than silicon to form uniform oxide particles;
After the particle formation step, the uniform oxide particles are subjected to a hydrophobic treatment to form hydrophobic oxide particles; and
A kneading step of kneading the hydrophobic oxide particles and the thermoplastic resin after the hydrophobic treatment step;
It is characterized by having.

As the fifth aspect of the present invention,
A method for producing an optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
A particle forming step of uniformly distributing silicon oxide and one or more kinds of metal oxides other than silicon to form uniform oxide particles;
A silica layer forming step of forming a silica layer on the surface of the uniform oxide particles after the particle forming step;
After the silica layer forming step, the silica layer is subjected to a hydrophobizing treatment to form hydrophobic oxide particles, and
A kneading step of kneading the hydrophobic oxide particles and the thermoplastic resin after the hydrophobic treatment step;
It is characterized by having.

  According to the first to third embodiments of the present invention, it is possible to provide an optical resin material and an optical element that have a refractive index that is thermally stable and that has excellent blue light transmittance while maintaining a constant moisture content. (See examples below). According to the fourth and fifth embodiments of the present invention, it is possible to manufacture an optical resin material and an optical element having a refractive index that is thermally stable and excellent in blue light transmittance while maintaining a constant moisture content. .

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for carrying out the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

The optical resin material according to the present invention contains a thermoplastic resin and hydrophobic oxide particles. The optical element according to the present invention is obtained by molding the optical resin material.
In the following, (1) thermoplastic resin and (2) hydrophobic oxide particles will be described, respectively, and then (3) optical resin material manufacturing method and (4) optical element manufacturing method and application examples, etc. Each will be explained.

(1) Thermoplastic resin The thermoplastic resin is not particularly limited as long as it is a transparent thermoplastic resin material generally used as an optical material. However, in consideration of processability as an optical element, an acrylic resin or a cyclic olefin is used. A resin, a polycarbonate resin, a polyester resin, a polyether resin, a polyamide resin, or a polyimide resin is preferable, and a cyclic olefin resin is particularly preferable, and examples thereof include compounds described in JP-A-2003-73559. Table 1 shows preferable compounds.

  In the optical resin material, the thermoplastic resin preferably has a water absorption of 0.2% by mass or less. Examples of the resin having a water absorption of 0.2% by mass or less include polyolefin resin (for example, polyethylene, polypropylene, etc.), fluororesin (for example, polytetrafluoroethylene, Teflon (registered trademark) AF (manufactured by DuPont), Top (made by Asahi Glass Co., Ltd.), cyclic olefin resin (for example, ZEONEX (made by Nippon Zeon), Arton (made by JSR), Apel (made by Mitsui Chemicals), TOPAS (made by Polyplastics), etc.), inden / Styrenic resins, polycarbonates and the like are suitable, but not limited to these.

  It is also preferable to use other resins compatible with these resins. When two or more kinds of resins are used, the water absorption rate is considered to be approximately equal to the average value of the water absorption rates of the individual resins, and the average water absorption rate only needs to be 0.2% or less.

(2) Hydrophobic oxide particles Hydrophobic oxide particles are fine particles obtained by subjecting the surface of uniform oxide particles to a hydrophobic treatment. “Uniform oxide particles” are composite oxide particles in which silicon oxide and one or more types of metal oxides other than silicon are uniformly distributed. Specifically, for example, silica that is silicon oxide and , Titanium oxide, zinc oxide, aluminum oxide, zirconium oxide, hafnium oxide, niobium oxide, tantalum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, yttrium oxide, lanthanum oxide, cerium oxide, indium oxide, tin oxide, oxide Composite oxide particles composed of one or more oxides of lead, each oxide being uniformly distributed.

  The above-mentioned “homogeneous oxide particles” are particles in a state where silicon oxide (silica or the like) in the particles and other metal oxides are averagely distributed without being localized. It is a particle having no refractive index distribution.

  The shape of the hydrophobic oxide particles is not particularly limited, but preferably spherical fine particles are used. Further, the particle size distribution is not particularly limited, but in order to achieve the effect of the present invention more efficiently, a material having a relatively narrow distribution is preferable to a material having a wide distribution. Used.

  The volume average particle size of the hydrophobic oxide particles is preferably 1 to 50 nm, and more preferably 2 to 30 nm. When applying hydrophobic oxide particles having a volume average particle diameter of 1 nm or less, it is not preferable because it is difficult to uniformly disperse the hydrophobic oxide particles in the thermoplastic resin, and hydrophobic particles having a volume average particle diameter of 50 nm or more. When the conductive oxide particles are applied, the light transmittance of the optical resin material (or an optical element formed thereof) is reduced, which is not preferable.

  The hydrophobic oxide particles include those in which a silica layer is formed on the surface of the uniform oxide particles and the surface of the silica layer is subjected to a hydrophobic treatment.

(3) Manufacturing method of optical resin material The manufacturing method of the optical resin material according to the present invention forms uniform oxide particles by uniformly distributing silicon oxide and one or more kinds of metal oxides other than silicon. Particle forming step, and after the particle forming step, the surface of the uniform oxide particles is subjected to a hydrophobic treatment to form hydrophobic oxide particles, and the hydrophobic oxide particles after the hydrophobic treatment step And a kneading step of kneading the thermoplastic resin.

(3.1) Particle Formation Step As a method for producing uniform oxide particles, a thermal decomposition method (a method of obtaining fine particles by thermally decomposing raw materials. Spray drying method, flame spray method, plasma method, gas phase reaction method, freezing Drying method, heated kerosene method, heated petroleum method), precipitation method (coprecipitation method), hydrolysis method (salt aqueous solution method, alkoxide method, sol-gel method), hydrothermal method (precipitation method, crystallization method, hydrothermal decomposition method) Hydrothermal oxidation method). Among these, the thermal decomposition method, the precipitation method, and the hydrolysis method are preferable methods from the viewpoint of producing uniform oxide particles having a small particle size. In producing the uniform oxide particles, a plurality of these methods may be combined.

(3.2) Hydrophobic treatment step Examples of the method of hydrophobizing the surface of uniform oxide particles include surface treatment with a surface modifier such as a coupling agent, polymer graft, and surface treatment with mechanochemical.

  Examples of the surface modifier used for the hydrophobic treatment on the surface of the uniform oxide particles include silane coupling agents, silicone oil-based, titanate-based, aluminate-based and zirconate-based coupling agents. These are not particularly limited, and can be appropriately selected depending on the types of uniform oxide particles and thermoplastic resin. Further, two or more surface treatments may be performed simultaneously or at different times.

  Specifically, for example, silane-based surface treatment agents include vinylsilazane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, trimethylalkoxysilane, dimethyldialkoxysilane, methyltrialkoxysilane, hexamethyldisilazane, and the like. Applicable, trimethylmethoxysilane, dimethyldimethoxysilane, methyltrimethoxysilane, hexamethyldisilazane and the like are preferable.

  Silicone oil based surface treatment agents include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, Methacryl-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, one-end reactive modified silicone oil, heterogeneous functional group-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, alkyl-modified silicone oil, higher fatty acid ester Modified silicone oil, hydrophilic special modified silicone oil, higher alkoxy modified silicone oil, It can be used grade fatty acid-containing modified silicone oil, a modified silicone oil such as fluorine-modified silicone oil.

  These surface treatment agents may be appropriately diluted with hexane, toluene, methanol, ethanol, acetone water or the like.

  Examples of the hydrophobic treatment method using the surface modifier include a wet heating method, a wet filtration method, a dry stirring method, an integral blend method, and a granulation method. In the case where the surface of uniform oxide particles having a volume average particle diameter of 100 nm or less is subjected to a hydrophobic treatment, it is preferable to apply a dry stirring method from the viewpoint of suppressing the aggregation of the particles.

  These surface modifiers may be used alone or in combination, and the properties of the uniform oxide particles (hydrophobic oxide particles) after the hydrophobic treatment obtained by the surface modifier used. However, the affinity with the thermoplastic resin used for obtaining the optical resin material can be increased by selecting the surface modifier. The ratio of the surface modifier is not particularly limited, but the ratio of the surface modifier may be 10 to 99 mass% with respect to the uniform oxide particles (hydrophobic oxide particles) after the hydrophobic treatment. Preferably, it is 30-98 mass%.

  In addition, between the particle forming step and the hydrophobizing treatment step, the surface of the uniform oxide particles obtained after the particle forming step is subjected to a complex oxide surface modification treatment with tetramethoxysilane or tetraethoxysilane. Alternatively, a silica layer made of tetramethoxysilane or tetraethoxysilane may be formed on the surface of the uniform oxide particles (silica layer forming step), and then the hydrophobic treatment may be performed on the surface of the silica layer.

  Further, in the hydrophobization treatment of the present embodiment, using a dry stirring method, silazanes are attached to the surface of uniform oxide particles (the silica layer when a silica layer is formed) and heated, It is preferable to form the surface of the hydrophobic oxide particles with polysilazane. It is preferable to use hexamethyldisilazane as the silazanes.

(3.3) Kneading step In the kneading step, a manufacturing method for producing an optical resin material by adding and kneading hydrophobic oxide particles to a molten thermoplastic resin, or a thermoplastic resin dissolved in a solvent A production method in which an optical resin material is prepared by mixing an organic solvent with hydrophobic oxide particles and then removing the organic solvent is a preferred embodiment.

  In the kneading step, the optical resin material is particularly preferably produced by a melt kneading method. Although it is possible to polymerize a thermoplastic resin in the presence of hydrophobic oxide particles or to produce hydrophobic oxide particles in the presence of a thermoplastic resin, polymerization of thermoplastic resins or hydrophobic oxide particles This is because special conditions are required in the fabrication of the above. In the melt-kneading method, an optical resin material can be produced by mixing thermoplastic resin and hydrophobic oxide particles produced by an existing method, and therefore, an inexpensive optical resin material can be usually produced.

  In the melt kneading, an organic solvent can be used. By using an organic solvent, the temperature of melt kneading can be lowered, and the deterioration of the thermoplastic resin can be easily suppressed. In that case, it is preferable to deaerate after melt-kneading to remove the organic solvent from the optical resin material.

  As an apparatus which can be used for melt kneading, a closed kneading apparatus or a batch kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, a roll, and the like can be given. Moreover, it can also manufacture using a continuous melt-kneading apparatus like a single screw extruder, a twin screw extruder, etc.

  When melt-kneading is used as the treatment mode of the kneading step, the thermoplastic resin and the hydrophobic oxide particles may be added and kneaded all at once, or may be added in stages and kneaded. In this case, in a melt-kneading apparatus such as an extruder, it is possible to add the components to be added step by step from the middle of the cylinder. However, when the thermoplastic resin is heated by melt kneading, it is preferable to first add a material that prevents thermal degradation of the thermoplastic resin, such as an antioxidant. If hydrophobic oxide particles are added thereafter, the temperature of melt kneading often increases, and the deterioration of the thermoplastic resin becomes remarkable without an antioxidant. On the other hand, light stabilizers are often colored due to thermal degradation. For this reason, in the melt-kneading process, it is preferable to add a light-resistant stabilizer in a later step as much as possible. Therefore, at least a part of the light stabilizer is added after the addition of the hydrophobic oxide particles.

  When the thermoplastic resin and the hydrophobic oxide particles are combined by melt kneading, the hydrophobic oxide particles can be added in a powder or aggregated state. Alternatively, the hydrophobic oxide particles can be added in a dispersed state in the liquid. When the hydrophobic oxide particles are added in a state dispersed in a liquid, it is preferable to perform deaeration after kneading.

  When the hydrophobic oxide particles are added in a state of being dispersed in the liquid, it is preferable to add the agglomerated particles dispersed in the primary particles in advance. Various dispersing machines can be used for dispersion, but a bead mill is particularly preferable. There are various kinds of beads, but those having a small size are preferable, and those having a diameter of 0.001 to 0.1 mm are particularly preferable.

  The uniform oxide particles are preferably added in a state of being hydrophobized (in the state of being made into hydrophobic oxide particles). However, the surface treatment agent and the uniform oxide particles are added at the same time, so that the thermoplastic resin and the uniform oxidation are added. A method such as an integral blend for compounding with physical particles may be used, and any other method may be used.

(4) Optical Element Manufacturing Method and Application Examples, etc. (4.1) Optical Element Manufacturing Method A method for manufacturing an optical element (for example, an optical resin lens) according to the present invention will be described.
In the production of the optical element, an optical resin material obtained through each process of the kneading process from the particle forming process is molded (molding process). Although it does not specifically limit as a shaping | molding method, From a viewpoint of characteristics, such as the low birefringence in a molding, mechanical strength, and a dimensional accuracy, a melt molding method is preferable. Examples of the melt molding method include press molding, extrusion molding, and injection molding. From the viewpoint of productivity, injection molding is preferable. In the case of a photocurable resin, cast polymerization or the like can be used.

  The molding conditions are appropriately selected according to the purpose of use or the molding method. For example, as the temperature of the optical resin material in injection molding, an appropriate fluidity is imparted to the optical resin material during molding. From the viewpoint of prevention of sink marks of products, distortion, prevention of silver streak due to thermal decomposition of optical resin materials, and effective prevention of yellowing of molded products, it is preferably within a range of 150 to 400 ° C. More preferably, it is in the range of 200 to 350 ° C, and particularly preferably in the range of 200 to 330 ° C.

  In injection molding, a molding method using carbon dioxide as a plasticizer can be used to improve fluidity. In addition, a technique for improving transferability by induction heating of the mold surface is also applicable.

  The molded product can be used in various forms such as a spherical shape, a rod shape, a plate shape, a cylindrical shape, a tubular shape, a tubular shape, a fibrous shape, a film or a sheet shape, and has a low birefringence, transparency, mechanical Since it is excellent in strength, heat resistance and low water absorption, it is suitably used as an optical resin lens that is one of the optical elements of the present invention, but may be used as other optical components.

  On the surface of the molded product made from the optical resin material according to the present invention, an inorganic compound, an organic silicon compound such as a silane coupling agent, an acrylic resin, a vinyl resin, a melamine resin, an epoxy resin, a fluorine resin, A hard coat layer made of a silicone resin or the like may be formed. Examples of the means for forming the hard coat layer include known methods such as a thermal curing method, an ultraviolet curing method, a vacuum deposition method, a sputtering method, and an ion plating method. Thereby, the heat resistance, optical characteristics, chemical resistance, abrasion resistance, water resistance, etc. of the molded product can be improved.

(4.2) Additive In addition, at the time of production of the optical resin material according to the present invention (including the steps from the particle molding step to the kneading step) and at the time of production of the optical element (including the molding step). May add various additives as needed. Examples of such additives include antioxidants, light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as ultraviolet absorbers and near infrared absorbers, lubricants, resin modifiers such as plasticizers, soft polymers, , Anti-clouding agents such as alcoholic compounds, colorants such as dyes and pigments, other antistatic agents, flame retardants and the like. They may be used alone or in combination.

(4.2.1) Antioxidants Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative degradation during molding of the optical resin material without lowering transparency, heat resistance and the like.

  As the phenolic antioxidant, conventionally known ones can be applied. For example, 2-t-butyl-6- (3-t-butyl-2-hydroxy- described in JP-A No. 63-179953). 5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate, etc. Acrylate compounds such as octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate described in JP-A-1-168463, and 2,2′-methylene-bis (4-methyl) -6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-to (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenylpropionate)) methane, , Pentaerythrmethyl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)), triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5- Alkyl-substituted phenolic compounds such as methylphenyl) propionate), 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4- Bisoctylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3 - triazine group-containing phenol compounds such as triazine.

  The phosphorus-based antioxidant is not particularly limited as long as it is a substance that is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris ( Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl)- Monophosphite compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di- Tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C 5) phosphite) diphosphite compounds such as and the like. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  Examples of the sulfur-based antioxidant include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3-thiodiprote. Pionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Can be mentioned.

  Furthermore, in addition to the above-mentioned phenol-based, phosphoric acid-based and sulfur-based antioxidants, amine-based antioxidants such as diphenylamine derivatives, nickel or zinc thiocarbamates, and the like are also applicable as antioxidants.

  The above-mentioned antioxidants can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range that does not impair the object of the present invention. It is preferably in the range of 0.001 to 20 parts by mass, more preferably in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass.

(4.2.2) Anti-turbidity agent As the anti-turbidity agent, a compound having the lowest glass transition temperature of 30 ° C. or less can be blended. This prevents the cloudiness of the thin film in the long-time high-temperature and high-humidity environment without degrading various properties such as transmittance, heat resistance, and mechanical strength, and in the long-time high-temperature and high-humidity environment. it can.

(4.2.3) Light-resistant stabilizer Light-resistant stabilizers (light stabilizers) are roughly classified into quenchers and radical scavengers. Benzophenone light stabilizers, benzotriazole light stabilizers, and triazine light stabilizers are classified as quenchers, and hindered amine light stabilizers are classified as radical scavengers. In the present invention, it is preferable to use a hindered amine light stabilizer (HALS) from the viewpoint of the transparency of the lens, the color resistance, and the like. Specific examples of such HALS can be selected from low molecular weight to medium molecular weight and high molecular weight.

  For example, among LA-77 (Asahi Denka), Tinuvin 765 (CSC), Tinuvin 123 (CSC), Tinuvin 440 (CSC), Tinuvin 144 (CSC), Hostavin N20 (Hoechst) As molecular weights of the order, LA-57 (Asahi Denka), LA-52 (Asahi Denka), LA-67 (Asahi Denka), LA-62 (Asahi Denka), 68 (manufactured by Asahi Denka), LA-63 (manufactured by Asahi Denka), Hostavin N30 (manufactured by Hoechst), Chimassorb 944 (manufactured by CSC), Chimassorb 2020 (manufactured by CSC), Chimassorb119 (manufactured by CSC), Tinuvin 622 (manufactured by CSC), Cubor 626 (as manufactured by CSC), Cb (Cy Ltd. ec), manufactured CyasorbUV-3529 (Cytec), and the like Uvasil299 (manufactured by GLC). In particular, it is preferable to use low and medium molecular weight HALS for the molded article (optical element) of the optical resin material, and high molecular weight HALS for the film-like optical resin material.

HALS is also preferably used in combination with a benzotriazole-based light-resistant stabilizer. For example, ADK STAB LA-32, LA-36, LA-31 (manufactured by Asahi Denka Kogyo), Tinuvin 326, Tinuvin 571, Tinuvin 234, Tinuvin 1130 (manufactured by CSC) and the like can be mentioned.
HALS is preferably used in combination with the various antioxidants described above. There are no particular restrictions on the combination of HALS and antioxidant, and combinations of phenols, phosphorus, sulfur and the like are possible, but combinations of phosphorus and phenols are particularly preferred.

(4.2.4) Other additives In addition to the antioxidants and light stabilizers described above, stabilizers such as heat stabilizers, weather stabilizers and near infrared absorbers; resin modifiers such as lubricants and plasticizers An anti-clouding agent such as a soft polymer or an alcohol compound; a colorant such as a dye or a pigment; an antistatic agent or a flame retardant; These compounding agents can be used alone or in combination of two or more, and the compounding amount is appropriately selected within a range not impairing the effects described in the present invention.

  In addition, by blending a compound having the lowest glass transition temperature of 30 ° C. or less into the optical resin material according to the present invention, without reducing various properties such as transparency, heat resistance, and mechanical strength, It can prevent cloudiness in long-term high temperature and high humidity environment.

(4.3) Application Example of Optical Element The optical element according to the present invention can be obtained by the above-described manufacturing method, and a specific application example to an optical component is as follows.
For example, as an optical lens or an optical prism, an imaging lens of a camera; a lens such as a microscope, an endoscope or a telescope lens; an all-light transmission lens such as a spectacle lens; a CD, a CD-ROM, or a WORM (recordable optical disk) , MO (rewritable optical disc; magneto-optical disc), MD (mini disc), optical disc pick-up lens such as DVD (digital video disc); laser scanning system lens such as laser beam printer fθ lens, sensor lens; Examples include prism lenses for camera viewfinder systems.

  Examples of optical disc applications include CD, CD-ROM, WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc), and the like. Other optical applications include light guide plates such as liquid crystal displays; optical films such as polarizing films, retardation films and light diffusion films; light diffusion plates; optical cards; liquid crystal display element substrates.

  Among these, the optical element according to the present invention is suitably used as a pickup lens or a laser scanning lens that requires low birefringence, and is most preferably used as a pickup lens.

Hereinafter, an optical pickup device 1 using an optical element molded from an optical resin material will be described with reference to FIG.
FIG. 1 is a schematic diagram showing the internal structure of the optical pickup device 1.

  In this embodiment, the target is a “high-density optical disk” using a so-called blue-violet laser light source having a used wavelength of 405 nm, the protective substrate thickness of this optical disk is 0.1 mm, and the storage capacity is about 30 GB.

As shown in FIG. 1, the optical pickup device 1 in this embodiment includes a semiconductor laser oscillator 2 that is a light source. On the optical axis of the blue light emitted from the semiconductor laser oscillator 2, a collimator 3, a beam splitter 4, a quarter wavelength plate 5, a diaphragm 6, and an objective lens 7 are arranged in a direction away from the semiconductor laser oscillator 2. Are sequentially arranged.
In addition, a sensor lens group 8 and a sensor 9 including two sets of lenses are sequentially disposed in a direction close to the beam splitter 4 and in a direction perpendicular to the optical axis of the blue light described above.

  The objective lens 7 that is an optical element is disposed at a position facing the optical disc D, and condenses the blue light emitted from the semiconductor laser oscillator 2 on one surface of the optical disc D. . Such an objective lens 7 is provided with a two-dimensional actuator 10, and the objective lens 7 is movable on the optical axis by the operation of the two-dimensional actuator 10.

Next, the operation of the optical pickup device 1 will be described.
The optical pickup device 1 in the present embodiment emits blue light from the semiconductor laser oscillator 2 at the time of recording information on the optical disc D or at the time of reproducing information recorded on the optical disc D. As shown in FIG. 1, the emitted blue light becomes a light beam L ₁ , is collimated to infinite parallel light through the collimator 3, and then is transmitted through the beam splitter 4 to be a quarter wavelength plate 5. Transparent. Furthermore, after sequentially passing through the aperture 6 and the objective lens 7 to form a converged spot on the information recording surface D ₂ through the protective substrate D ₁ of the optical disc D.

Light that formed the concentrated light spot is modulated by the information recording surface D ₂ of the optical disk D by the information pit is reflected by the information recording surface D _2. Then, the reflected light becomes a light beam L ₂ , is sequentially transmitted through the objective lens 7 and the diaphragm 6, is changed in polarization direction by the quarter wavelength plate 5, and is reflected by the beam splitter 4. After that, astigmatism is given through the sensor lens group 8, received by the sensor 9, and finally converted into an electric signal by being photoelectrically converted by the sensor 9.
Thereafter, such an operation is repeatedly performed, and the operation of recording information on the optical disc D and the operation of reproducing information recorded on the optical disc D are completed.

Incidentally, the magnitude of the thickness and the information pits of the protective substrate D ₁ of the optical disc D, also the numerical aperture NA required for the objective lens 7 different. In the present embodiment, the optical disc D is a high density, and its numerical aperture is set to 0.85.

(4.4) Characteristics of Optical Element The optical element according to the present invention preferably has a light transmittance of 405 nm at a thickness of 3 mm and 70% or more. This is because when the light transmittance is less than 70%, the data reading accuracy is lowered. Many of the hydrophobic oxide particles do not absorb 405 nm light, but the thermoplastic resin may absorb a little. In such a case, it is expected that the light transmittance at 405 nm is increased as an optical resin material by increasing the fraction of the hydrophobic oxide particles.

(1) Preparation of sample (1.1) Preparation of optical resin material 1 (SiO ₂ / ZrO ₂ (SiO ₂ molar fraction 80%)-based material) 463.1 g of pure water, 104.8 g of 26% ammonia water, While maintaining a liquid temperature of 25 ° C. with respect to a mixed liquid of 4255.0 g of methanol, a mixed liquid of 3648 g of tetramethoxysilane (TMOS) and 229.4 g of methanol, 643.2 g of pure water, and 104.8 g of 26% ammonia water. The mixture was added dropwise over 150 minutes. Thereafter, 2139 g of zirconium tetraisopropoxide and 150 g of isopropanol were added to the mixture over 100 minutes to obtain a silica / zirconia mixed sol.

  Thereafter, while the sol was heated and distilled under normal pressure, pure water was dropped with the volume kept constant with respect to the sol, the tower top temperature reached 100 ° C., and the pH value became 8 or less. When this was confirmed, dropping of pure water was terminated to obtain a fine particle dispersion (particle formation step).

  Thereafter, the fine particle dispersion was spray-dried, and the obtained fine particles were further heated at 200 ° C. in the atmosphere for 1 hour. While stirring 30 g of the powder obtained after heating under argon, 4 g of hexamethyldisilazane was added to the powder. Thereafter, the powder added with hexamethyldisilazane was heated at 200 ° C. for 30 minutes and subsequently cooled to room temperature (hydrophobization treatment step). As a result, “hydrophobic oxide particles 1” in which silica and zirconia were uniformly combined were obtained.

  As a result of TEM observation, the volume-converted average particle diameter of the hydrophobic oxide particles 1 was 10 nm. Thereafter, the hydrophobic oxide particles 1 and a thermoplastic resin (cycloolefin resin, APEL5014 manufactured by Mitsui Chemicals) were melted and kneaded while degassing to produce “Optical Resin Material 1” (kneading step).

  The content (filling rate) of the hydrophobic oxide particles 1 in the optical resin material 1 was set to 20% by volume with respect to the thermoplastic resin. In the kneading process of melt kneading, lab plast mill KF-6V was used and kneaded at 100 rpm for 10 minutes under nitrogen, and degassed under reduced pressure at 20 Torr for 2 minutes before the completion. During melt kneading, 10 parts by weight of cyclohexylmethyldimethoxysilane per 100 parts by weight of the hydrophobic oxide fine particles are added to the mixture of the hydrophobic oxide fine particles 1 and the thermoplastic resin to treat the surface of the hydrophobic oxide particles 1. Went.

(1.2) Production of optical resin material 2 (SiO ₂ / ZrO ₂ (SiO ₂ molar fraction 80%)-based material) In the production of optical resin material 1, the filling rate of hydrophobic oxide particles 1 is determined. The volume was changed to 30% by volume. Otherwise, the “optical resin material 2” was prepared in the same manner as the optical resin material 1.

(1.3) Production of Optical Resin Material 3 (SiO ₂ / ZrO ₂ (SiO ₂ Molar Fraction 80%) Type Material) In production of optical resin material 1, instead of hydrophobic oxide particles 1, the following Thus, “hydrophobic oxide particles 3” having a silica layer were prepared. Otherwise, the “optical resin material 3” was prepared in the same manner as in the production of the optical resin material 1.

  4000 g of pure water was added to 40 g of the particles obtained after spray-drying in the production of the optical resin material 1, and the pH value of the dispersion was adjusted to 11.3 using ammonia water. Thereafter, the dispersion was cooled to 7 ° C. while stirring the dispersion of the particles. Thereafter, 20 g of tetraethoxysilane was slowly dropped into the dispersion, and the dispersion was stirred for 1 hour. Thereafter, the temperature of the dispersion was raised to 75 ° C., and the dispersion was further stirred for 1 hour. Thereafter, the stirred dispersion was centrifuged at 15000 rpm for 10 minutes, and the supernatant of the dispersion was removed. Thereafter, particles obtained after centrifugation were dispersed in methanol, and the dispersion was spray-dried again to obtain a surface-treated powder with a silica-based coupling agent (silica layer forming step) .

  While stirring 30 g of this powder under argon, 4 g of hexamethyldisilazane was added to the powder. Thereafter, the powder to which hexamethyldisilazane was added was heated at 200 ° C. for 30 minutes and subsequently cooled to room temperature (hydrophobization treatment step). As a result, “hydrophobic oxide particles 3” in which silica and zirconia were uniformly combined were obtained.

(1.4) Production of optical resin material 4 (SiO ₂ / ZrO ₂ (SiO ₂ molar fraction 80%)-based material) 20 g of tetraethoxysilane used in the silica layer formation step in the production of optical resin material 3 Was changed to 15 g of tetramethoxysilane. Otherwise, the “optical resin material 4” was prepared in the same manner as the optical resin material 3.

(1.5) Production of optical resin material 5 (SiO ₂ / TiO ₂ (SiO ₂ molar fraction 60%)-based material) In production of optical resin material 3, it was used to obtain a silica / zirconia mixed sol. Zirconium tetraisopropoxide 2139 g was changed to titanium tetraisopropoxide 2274 g. Otherwise, the “optical resin material 5” was prepared in the same manner as the optical resin material 3.

(1.6) Production of optical resin material 6 (SiO ₂ / Al ₂ O ₃ (SiO ₂ molar fraction 60%)-based material) In producing optical resin material 3, when obtaining a silica / zirconia mixed sol The zirconium tetraisopropoxide used 2139 g was changed to aluminum isopropoxide 2492 g. Otherwise, the “optical resin material 6” was prepared in the same manner as the optical resin material 3.

(1.7) Production of optical resin material 7 (SiO ₂ / ZrO ₂ (SiO ₂ molar fraction 80%)-based material) In the production of optical resin material 1, the hydrophobic treatment was not performed. Otherwise, the “optical resin material 7” was prepared in the same manner as in the production of the optical resin material 1.

(1.8) Production of optical resin material 8 (SiO ₂ / ZrO ₂ (SiO ₂ molar fraction 80%)-based material) In production of optical resin material 1, zirconium tetrazirconium was used to obtain a silica / zirconia mixed sol. A place where a mixture of 5969 g of isopropoxide and 150 g of isopropanol was added over 100 minutes was added over 24 hours, and the above hydrophobization treatment was not performed. Otherwise, “Optical Resin Material 8” was produced in the same manner as in the production of Optical Resin Material 1.

(1.9) Production of Samples 1 to 8 Each of the optical resin materials 1 to 8 obtained above was pressed under vacuum at 160 ° C. and 10 Torr to produce a molded body having a diameter of 11 mm and a thickness of 3 mm. The molded body was designated as “Samples 1-8”. Each sample 1 to 8 was subjected to surface polishing.

(2) Physical property measurement of each sample 1-8 (optical resin materials 1-8) (2.1) Particle size distribution measurement of hydrophobic oxide particles in each sample 1-8 From each sample 1-8 using a microtome Sections of about 100 nm were prepared, and each section of samples 1 to 8 was observed with a transmission electron microscope (Hitachi H-800) (100,000 times), and the obtained images were averaged in terms of volume for each of samples 1 to 8. Converted to diameter. The conversion results are shown in Table 2 below.

(2.2) Measurement of Refractive Index of Samples 1-8 The refractive index of each sample 1-8 at a temperature of 25 ° C. and a wavelength of 588 nm was measured using an automatic refractometer (manufactured by Kalnew Optical Industry: KPR-200). . The measurement results are shown in Table 2 below.

(2.3) Measurement of transmittance of each sample 1-8
The transmittance of each sample 1 to 8 was measured at a wavelength of 405 nm by a transmittance measuring method based on ASTM D 1003. The measurement results are shown in Table 2 below.

(2.4) Measurement of water absorption rate of samples 1 to 8 Using a high-temperature and high-humidity machine (PR-2PK, manufactured by ESPEC Corporation), each sample 1 to 8 was previously 100 ° C. and 10% RH for 100 hours. It was dried, and then stored at 60 ° C. and 90% RH for 500 hours to absorb moisture. The water absorption rate of each sample 1-8 was computed from the weight increase of the sample 1-8 after moisture absorption with respect to the weight of the sample 1-8 after drying. The calculation results are shown in Table 2 below. The weights of the samples 1 to 8 after drying were measured by the Karl Fischer method using a dry organic solvent.

(2.5) Measurement of Humidity Dependence of Refractive Index in Samples 1 to 8 Using a high-temperature and high-humidity machine (PR-2PK manufactured by Espec Corporation), each sample 1 to 8 was previously set at 100 ° C. and 10%. It was dried with RH for 100 hours, and then stored at 60 ° C. and 90% RH for 500 hours to absorb moisture. Then, using an automatic refractometer (manufactured by Kalnew Optical Industry: KPR-200), each refractive index at a temperature of 25 ° C. and a wavelength of 588 nm of samples 1 to 8 after drying and samples 1 to 8 after moisture absorption is measured, The humidity dependence of the refractive index (= (refractive index of samples 1 to 8 after moisture absorption) / (refractive index of samples 1 to 8 after drying) × 100 [%]) was calculated for each of samples 1 to 8. The calculation results are shown in Table 2 below.

(2.6) Measurement of temperature dependence of refractive index in each sample 1 to 8 Using an automatic refractometer (KPR-200, manufactured by Kalnew Optical Industry), the temperature of each sample 1 to 8 is from 25 ° C to 75 ° C. The refractive index at a wavelength of 588 nm was measured, and dn / dT (rate of change of refractive index with respect to temperature change) in each sample 1 to 8 was calculated. In addition, dn / dT in the thermoplastic resin was calculated by the same method for the thermoplastic resin to which the hydrophobic oxide particles were not added (cycloolefin resin, APEL5014 manufactured by Mitsui Chemicals). Based on these calculation results, the change rate of dn / dT of each sample 1 to 8 was calculated by the following formula, and this was expressed as the refractive index temperature dependency. The calculation results are shown in Table 2 below.

  dn / dT change rate (%) = (dn / dT in thermoplastic resin A−dn / dT in samples 1 to 8) / (dn / dT in thermoplastic resin A) × 100

  As shown in Table 2, when the results of Samples 1 and 2 and Samples 7 and 8 are compared, Samples 1 and 2 have a higher refractive index than that of Samples 7 and 8, while maintaining a constant water content. It is found that it is useful to apply particles that have been subjected to a hydrophobic treatment as an inorganic substance to be mixed into the thermoplastic resin. Similarly, when the results of Samples 3 to 6 and Samples 7 and 8 are compared, Samples 3 to 6 also have a constant water content compared to Samples 7 and 8, and the refractive index is thermally stable. It can be seen that the particles are excellent in blue light transmittance and are useful even if they have a silica layer as long as they are hydrophobized.

It is a schematic diagram which shows the internal structure of an optical pick-up apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 2 Semiconductor laser oscillator 3 Collimator 4 Beam splitter 5 1/4 wavelength plate 6 Aperture 7 Objective lens (optical element)
8 Sensor lens group 9 Sensor 10 Two-dimensional actuator D Optical disk D ₁ Protection substrate D ₂ Information recording surface

Claims (14)

An optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
The hydrophobic oxide particles are particles obtained by subjecting uniform oxide particles in which silicon oxide and one or more kinds of metal oxides other than silicon are uniformly distributed to a hydrophobic treatment. Optical resin material. The optical resin material according to claim 1,
The optical resin material, wherein the hydrophobic treatment is a treatment in which silazanes are attached to the surface of the uniform oxide particles and heated. In the optical resin material according to claim 2,
An optical resin material, wherein the silazanes are hexamethyldisilazane. In the optical resin material as described in any one of Claims 1-3,
An optical resin material, wherein the surface of the hydrophobic oxide particles is formed of polysilazane. In the optical resin material according to any one of claims 1 to 4,
An optical resin material, wherein the hydrophobic oxide particles have a particle size of 1 to 50 nm. An optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
The hydrophobic oxide particles are subjected to a hydrophobic treatment on uniform oxide particles in which silicon oxide and one or more kinds of metal oxides other than silicon are uniformly distributed and a silica layer is formed on the surface. An optical resin material, characterized in that the optical resin material is a fine particle. In the optical resin material according to claim 6,
An optical resin material, wherein the silica layer is formed of tetramethoxysilane or tetraethoxysilane. In the optical resin material according to claim 6 or 7,
The hydrophobizing treatment is a treatment in which silazanes are attached to the surface of the silica layer and heating is performed. The optical resin material according to claim 8,
An optical resin material, wherein the silazanes are hexamethyldisilazane. In the optical resin material according to any one of claims 6 to 9,
An optical resin material, wherein the surface of the hydrophobic oxide particles is formed of polysilazane. In the optical resin material according to any one of claims 6 to 10,
An optical resin material, wherein the hydrophobic oxide particles have a particle size of 1 to 50 nm.   An optical element molded using the optical resin material according to claim 1. A method for producing an optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
A particle forming step of uniformly distributing silicon oxide and one or more kinds of metal oxides other than silicon to form uniform oxide particles;
After the particle formation step, the uniform oxide particles are subjected to a hydrophobic treatment to form hydrophobic oxide particles; and
A kneading step of kneading the hydrophobic oxide particles and the thermoplastic resin after the hydrophobic treatment step;
A method for producing an optical resin material, comprising: A method for producing an optical resin material containing a thermoplastic resin and hydrophobic oxide particles,
A particle forming step of uniformly distributing silicon oxide and one or more kinds of metal oxides other than silicon to form uniform oxide particles;
A silica layer forming step of forming a silica layer on the surface of the uniform oxide particles after the particle forming step;
After the silica layer forming step, the silica layer is subjected to a hydrophobizing treatment to form hydrophobic oxide particles, and
A kneading step of kneading the hydrophobic oxide particles and the thermoplastic resin after the hydrophobic treatment step;
A method for producing an optical resin material, comprising:

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