JP2006299032A - Thermoplastic resin composition and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition capable of aiming at the improvement of heat resistant stability and light transmittance, and an optical element. <P>SOLUTION: This thermoplastic resin composition is provided by showing ≤2% ratio of evaporated amount of vaporizable materials having evaporating property added during its production process or generated by the decomposition reaction of the thermoplastic resin or inorganic fine particles at a time point of heating the thermoplastic resin composition for 2 hrs at 250°C temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin composition and an optical element, and more particularly to a thermoplastic resin composition and an optical element that are suitably used as a lens, a filter, a grating, an optical fiber, a flat optical waveguide, and the like.

  Information equipment such as a player, a recorder, and a drive for reading and recording information with respect to an optical information recording medium (hereinafter also referred to as a medium) such as an MO, CD, and DVD is provided with an optical pickup device. Yes. The optical pickup device includes an optical element unit that irradiates a medium with light having a predetermined wavelength emitted from a light source, and receives the reflected light with a light receiving element. The optical element unit transmits the light to the medium. An optical element such as a lens for condensing light by a reflection layer or a light receiving element is included.

  The optical element of the optical pickup device described above is preferably made of plastic as a material in that it can be manufactured at low cost by means such as injection molding. As a plastic applicable to an optical element, a copolymer of a cyclic olefin and an α-olefin (for example, see Patent Document 1) is known, but a substance containing a cyclic olefin is a refractive index due to a change in humidity. However, it is difficult to obtain the desired effect because of the stability of the refractive index due to temperature change.

Therefore, as a polymeric optical product capable of reducing the temperature sensitivity of the refractive index, a polymeric host material having a temperature sensitive optical vector X ₁ and a temperature sensitive optical vector X ₂ having a polymeric shape. A polymeric optical product and a production method comprising fine particles dispersed in a host material have been developed (see, for example, Patent Document 1).

JP 2002-105131 A JP 2002-207101 A

However, in the case of the polymer optical product described in Patent Document 1 described above, in the production process, a fine particle dispersion medium, a fine particle surface treatment agent, a dispersant for dispersing fine particles in a polymer host material, a polymer A volatile substance such as a solvent for the gaseous host material, a monomer as a raw material for the polymeric host material, a polymerization initiator used for the polymerization reaction of the polymeric host material, and various catalysts is used. In the process, such a volatile substance is subjected to a removal process or a non-volatile process using a chemical reaction.
In addition to the various volatile substances described above, volatile substances are also included in substances generated due to the decomposition reaction of the thermoplastic resin or inorganic fine particles at high temperatures.
Such a volatile substance dissolves in the polymer host substance and is easily retained in the polymer optical product by being adsorbed to the fine particles, and the various characteristics of the polymer optical product such as thermal expansion at the time of temperature change. There is a problem that the physical properties are greatly affected.

  Further, the influence of volatile substances is unclear at present, and no specific examples are disclosed from the viewpoint of the volatilization amount of volatile substances in polymer optical products.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a thermoplastic resin composition and an optical element capable of improving heat stability and light transmittance.

In order to solve the above problems, the thermoplastic resin composition according to the invention of claim 1 is:
In the thermoplastic resin composition containing the thermoplastic resin and inorganic fine particles,
Containing a volatile substance having volatility, which is added in the production process or generated by a decomposition reaction of the thermoplastic resin or inorganic fine particles in the production process;
The volatile substance has a volatilization amount ratio of 2% or less with respect to the entire composition when heated at a temperature of 250 ° C. for 2 hours.

  According to the first aspect of the present invention, the ratio of the volatilization amount of the volatile substance to the entire composition at the time of heating at 250 ° C. for 2 hours is 2% or less, so that the strength in the thermoplastic resin composition Can be prevented from being greatly reduced, and deformation and thermal expansion can be prevented.

  The thermoplastic resin composition according to the invention of claim 2 contains the inorganic fine particles whose surface is treated with at least one kind of surface treatment agent among silane or titanium surface treatment agents. Features.

  According to the second aspect of the present invention, the inorganic fine particles are subjected to a surface treatment with at least one of the silane-based and titanium-based surface treatment agents, thereby improving the strength of the inorganic fine particles. Thus, the strength of the thermoplastic resin composition containing the inorganic fine particles can be improved.

  The thermoplastic resin composition according to a third aspect of the present invention is characterized in that the content of the inorganic fine particles is within a range of 10 to 90% with respect to the entire composition.

  According to the invention described in claim 3, when the content of the inorganic fine particles with respect to the entire composition is 10% or more, the effect of improving the physical properties by mixing the inorganic fine particles can be exhibited. While maintaining the ratio of the minimum required thermoplastic resin in the whole composition, it can prevent that workability is impaired.

  The thermoplastic resin composition according to the invention described in claim 4 is characterized in that the inorganic fine particles have a volume average dispersed particle diameter of 30 nm or less.

  According to invention of Claim 4, generation | occurrence | production of the light scattering resulting from the inorganic fine particle disperse | distributed in the composition can be suppressed.

  The thermoplastic resin composition according to the invention described in claim 5 is characterized in that the thermoplastic resin contains a cyclic olefin resin.

  According to invention of Claim 5, high dimensional stability is maintainable by containing the cyclic polyolefin which has low hygroscopicity.

  An optical element according to a sixth aspect of the invention is characterized by being molded using the thermoplastic resin composition according to any one of the first to fifth aspects.

  According to the invention described in claim 6, it is possible to improve the light transmittance and the linear expansion coefficient.

  According to the present invention, it is possible to prevent a significant decrease in strength, deformation and thermal expansion, and to improve the light transmittance, thereby improving heat resistance stability and transparency. Can do.

  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 implementing 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.

First, the thermoplastic resin composition in the present embodiment will be described.
The thermoplastic resin composition in the present embodiment contains a thermoplastic resin, inorganic fine particles, and a volatile substance. Details of the thermoplastic resin, the inorganic fine particles, and the volatile substance will be described below. .
The thermoplastic resin in the present embodiment is not particularly limited as long as it is a transparent thermoplastic resin generally used as an optical material. From the viewpoint of workability as an optical element, an acrylic resin, a cyclic resin An olefin 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. For example, compounds described in JP-A-2003-73559 can be exemplified, and preferred compounds are shown in Table 1 below.

  In addition, it is preferable that the thermoplastic resin in this embodiment has a water absorption of 0.2% or less from the viewpoint of dimensional stability. Examples of the resin having a water absorption rate of 0.2% or less include fluorine resins such as polyolefin resins such as polyethylene and polypropylene, polytetrafluoroethylene, Teflon (registered trademark) AF (manufactured by DuPont), and Cytop (manufactured by Asahi Glass). Resin, cyclic olefin resins such as ZEONEX (manufactured by Nippon Zeon), Arton (manufactured by JSR), Appel (manufactured by Mitsui Chemicals), TOPAS (manufactured by Chicona), indene / styrene-based resins, polycarbonate, and the like are suitably used. However, it is not particularly limited.

  The water absorption rate of the thermoplastic resin is more preferably 0.1% or less. This is because when the water absorption rate of the thermoplastic resin is high, even if the volatile material is reduced, the amount of the volatile material is increased by absorbing water again. This is because various physical properties may be affected.

Moreover, it is preferable that the thermoplastic resin mentioned above is used together with other resin with compatibility.
Further, when two or more kinds of resins described above are used, the water absorption rate of the thermoplastic resin composed of two or more types of resins is considered to be substantially the same as the average value of the water absorption rate of each resin. The rate may be 0.2% or less.

  On the other hand, as the inorganic fine particles in the present embodiment, oxide fine particles, sulfide fine particles, selenide fine particles, telluride fine particles, phosphides, double oxide fine particles, oxo acid salt fine particles, double salt fine particles, complex salt fine particles and the like are used. Can do. More specifically, 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, lead oxide, lithium niobate, potassium niobate, lithium tantalate, etc. that are composed of these oxides, phosphates, sulfates, etc. formed in combination with these oxides, Examples thereof include, but are not limited to, zinc sulfide, cadmium sulfide, zinc selenide, cadmium selenide and the like.

As the inorganic fine particles, fine particles having a semiconductor crystal composition can be suitably used. The semiconductor crystal composition is not particularly limited, but a semiconductor crystal composition that does not absorb, emit light, or fluoresce in a wavelength region used as an optical element is preferable. Specific examples of the composition include simple elements of Group 14 elements of the periodic table such as carbon, silicon, germanium and tin, simple elements of Group 15 elements of the periodic table such as phosphorus (black phosphorus), and periodic tables such as selenium or tellurium. A group 16 element simple substance, a compound composed of a plurality of Group 14 elements such as silicon carbide (SiC), tin (IV) (SnO ₂ ), tin sulfide (II, IV) (Sn (II) Sn (IV ) S _3), tin sulfide (IV) (SnS _2), tin sulfide (II) (SnS), selenium tin (II) (SnSe), tellurium tin (II) (SnTe), lead sulfide (II) ( PbS), lead selenide (II) (PbSe), lead telluride (II) (PbTe) periodic table group 14 element and periodic table group 16 element compound, boron nitride (BN), boron phosphide (BP), boron arsenide (BAs), aluminum nitride (AlN), aluminum phosphide (Al ), Aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium antimonide (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb) and other group 13 elements of the periodic table and group 15 elements of the periodic table (or III-V compound semiconductors), aluminum sulfide (Al ₂ S) ₃ ), aluminum selenide (Al ₂ Se ₃ ), gallium sulfide (Ga ₂ S ₃ ), gallium selenide (Ga ₂ Se ₃ ), gallium telluride (Ga ₂ Te ₃ ), indium oxide (In ₂ O ₃ ) , indium sulfide (In ₂ S _3), indium selenide (In ₂ Se _3), telluride, indium In ₂ Te ₃₎ Periodic Table compounds of a Group 13 element and Periodic Table Group 16 element such as, thallium chloride (I) (TlCl), thallium bromide (I) (TlBr), thallium iodide (I) ( Compounds of group 13 elements of the periodic table and elements of group 17 of the periodic table, such as TlI), zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide ( CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe), etc. And compounds of Group 16 elements of the periodic table (or II-VI group compound semiconductors), arsenic sulfide (III) (As ₂ S ₃ ), arsenic selenide (III) (As ₂ Se ₃ ), arsenic telluride (III ) ( s ₂ Te _3), antimony sulfide _{(III) (Sb 2 S 3} ), selenium antimony _{(III) (Sb 2 Se 3} ), antimony telluride _{(III) (Sb 2 Te 3} ), bismuth sulfide (III) ( Bi ₂ S ₃ ), bismuth selenide (III) (Bi ₂ Se ₃ ), bismuth telluride (III) (Bi ₂ Te ₃ ), etc. Compounds of periodic table group 11 elements and periodic table group 16 elements such as copper oxide (I) (Cu ₂ O), copper selenide (Cu ₂ Se), copper chloride (I) (CuCl), Compounds of Group 11 elements of the periodic table and Group 17 elements of the periodic table such as copper (I) bromide (CuBr), copper (I) iodide (CuI), silver chloride (AgCl), silver bromide (AgBr) , Compounds of Group 10 elements of the periodic table and Group 16 elements of the periodic table, such as nickel oxide (II) (NiO), oxidation Baltic (II) (CoO), compounds of cobalt sulfide (II) (CoS) periodic table Group 9 element and Periodic Table Group 16 element such as, triiron tetraoxide (Fe ₃ O _4), iron sulfide (II ) Compound of periodic table group 8 element such as (FeS) and periodic table group 16 element, Compound of periodic table group 7 element such as manganese (II) (MnO) and periodic table group 16 element, Compounds of Periodic Table Group 6 elements and Periodic Table Group 16 elements such as molybdenum sulfide (IV) (MoS ₂ ), tungsten oxide (IV) (WO ₂ ), vanadium oxide (II) (VO), vanadium oxide ( IV) (VO ₂ ), tantalum oxide (V) (Ta ₂ O ₅ ) and other periodic table group 5 elements and periodic table group 16 elements, titanium oxide (TiO ₂ , Ti ₂ O ₅ , Ti ₂₎ O _3, Ti ₅ O _9, etc.) compounds of the periodic table group 4 element and periodic table group 16 element such as, sulfide Magne Um (MgS), compounds of Group 2 elements and Periodic Table Group 16 element such as magnesium selenide (MgSe), cadmium (II) oxide Chromium _{(III) (CdCr 2 O 4} ), cadmium selenide ( II) Chalcogen spinels such as chromium (III) (CdCr ₂ Se ₄ ), copper sulfide (II) chromium (III) (CuCr ₂ S ₄ ), mercury selenide (II) chromium (III) (HgCr ₂ Se ₄ ) And barium titanate (BaTiO ₃ ).

In addition, G. Schmid et al., Adv. Mater. (BN) ₇₅ (BF ₂ ) ₁₅ F ₁₅ described in 1991, Vol. 4, p. Fenske et al., Angew. Chem. Int. Ed. Engl. , 1990, Vol. 29, p.1452, Cu ₁₄₆ Se ₇₃ (triethylphosphine) ₂₂ described in the semiconductor cluster whose structure is determined is exemplified as well.

  As the inorganic fine particles described above, one kind of inorganic fine particles may be used, or a plurality of kinds of inorganic fine particles may be used in combination. Moreover, it is also possible to use inorganic particles having a composite composition as the inorganic fine particles.

  The volume average particle diameter of the inorganic fine particles is preferably 30 nm or less. If the volume average particle diameter of the inorganic particles is 30 nm or less, light scattering caused by the inorganic particles can be suppressed, and high transparency can be obtained.

In the case where a mixture of particles having different particle size distributions is used, one type of average particle size is 30 nm or less, the other is 30 nm or more, and the average particle size is 30 nm or less. Is also possible.
However, in this case, particles having an average particle diameter of 30 nm or more are preferably as small as possible, and specifically 10 nm or less.

Furthermore, the lower limit of the volume average particle diameter of the inorganic particles is preferably 1 nm or more. This is because if the thickness is 1 nm or more, the specific surface area does not become excessive, and the treatment agent necessary for the surface treatment for obtaining affinity with the resin can be set in an appropriate range. That is, when the inorganic particles are spherical, and the total volume is the same, the specific surface area is inversely proportional to the average particle size.
For example, when the average particle size is changed from 30 nm to 1 nm, the specific surface area is 30 times. Therefore, when inorganic fine particles having an average particle diameter of 30 nm are used, the required amount of the surface treatment agent is 10% of the total volume. On the other hand, when inorganic fine particles having an average particle diameter of 1 nm are used, the required amount of the surface treatment agent becomes 30 times, which cannot be realized.

  Further, the content of the inorganic fine particles with respect to the above-described thermoplastic resin composition is preferably 10% or more and 90% or less, and more preferably 20% or more and 80% or less. If the content of the inorganic fine particles is 10% or more, the effect of improving the physical properties by mixing the inorganic fine particles can be exhibited. If the content is 90% or less, the necessary resin ratio is maintained and the original content is maintained. This is because it is possible to prevent deterioration of various properties such as processability, which is an advantage of the resin.

The method for producing the inorganic fine particles described above is not particularly limited, and a conventionally known method can be used. For example, a metal halide or an alkoxy metal is used as a raw material and water is contained. The desired oxide fine particles can be obtained by hydrolysis in the reaction system. At this time, a method of using an organic acid, an organic amine or the like in combination is also used for stabilizing the fine particles.
As a specific example, in the case of titanium dioxide fine particles, it can be produced by the method described in Journal of chemical engineering of Japan, 1998, Vol. 1, No. 1, p.21-28.
In the case of zinc sulfide fine particles, the method described in Journal of physical chemistry, 1996, Vol. 100, p.468-471, or dimethylzinc or zinc chloride as a raw material, sulfided with hydrogen sulfide or sodium sulfide, etc. In this case, it can be produced by a method of adding a surface treatment agent.

The inorganic fine particles prepared by the above-described method are subjected to a surface treatment with a coupling agent such as a silane, silicone oil, titanate, aluminate or amino acid which is a surface treatment agent.
Since the above-mentioned coupling agent has different characteristics such as reaction rate, it is appropriately selected according to the kind of inorganic fine particles to be used, conditions during surface treatment, etc., and only one kind may be used or a plurality of kinds may be used in combination. May be. When surface treatment is performed using two or more types of coupling agents, the surface treatment with various coupling agents may be performed simultaneously or at different times.
Also, depending on the coupling agent used, the properties of the resulting inorganic fine particles after surface treatment may differ, so the coupling agent to be used is appropriately selected in consideration of the affinity of the thermoplastic resin to be dispersed. May be.

  Silane coupling agents include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetraphenoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, methyltriethoxysilane, methyltriethoxysilane. Phenoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, 3-methylphenyltrimethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiphenoxysilane, trimethylmethoxysilane, triethylethoxysilane, triphenylmethoxy Silane, triphenylphenoxysilane, etc. are mentioned.

  Examples of the titanium-based coupling agent include tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecylbenzenesulfonyl titanate, and bis (dioctyl pyrophosphate) oxyacetate titanate.

  The ratio of the coupling agent to the inorganic fine particles is not particularly limited, but is preferably in the range of 5 to 200%, and more preferably in the range of 10 to 100%.

  As a surface treatment method using such a surface treatment agent, a method in which a surface treatment agent is directly sprayed on a powder of inorganic particles and then dried, a method in which a surface treatment agent is sprayed in a solution and then dried, Any method can be applied, such as a method in which a surface treatment agent is added to the dispersion and reacted, or a method in which the surface treatment agent is added when the inorganic fine particles and the resin are combined by melt kneading.

The inorganic fine particles that have been surface-treated by the above-described method are mixed in a thermoplastic resin, whereby a desired thermoplastic resin composition is obtained.
As a method of mixing the thermoplastic resin and the inorganic fine particles, it is preferable to use a melt kneading method from the viewpoint of reducing the amount of volatile substances used. As an apparatus applicable to the melt kneading method, a lab plast mill A closed kneading apparatus or a batch kneading apparatus such as a Brabender, a Banbury mixer, a kneader and a roll.
In addition, as an apparatus used for the melt-kneading method, a continuous melt-kneading apparatus such as a single-screw extruder or a twin-screw extruder can be used.

When the melt kneading method is used as a method for producing the thermoplastic resin composition, the raw material thermoplastic resin and the inorganic fine particles may be added and kneaded all at once, or divided and added in stages. Also good.
In the case of using a continuous melt kneader such as an extruder, it is also possible to add components to be added step by step from the middle of the cylinder.
In addition, after mixing in advance, components other than the thermoplastic resin that were not added in advance are added, and even when melt-kneading, these may be added all at once and kneaded, or added in stages. And kneading.
As a method of dividing and adding the thermoplastic resin and the inorganic fine particles described above, a method of adding one component in several times, a method of adding one component at a time, and adding different components in stages, or these methods A combined method may be used.

Moreover, in the case of the manufacturing method using a melt-kneading method, the inorganic fine particles described above can be added in a powder or aggregated state. On the other hand, it is possible to add the inorganic fine particles dispersed in the liquid, but in this case, it is necessary to perform a devolatilization treatment after the kneading.
In addition, when adding in the state disperse | distributed in the liquid, it is preferable to add, after previously disperse | distributing the aggregated particle to a primary particle.

In addition, as the dispersion treatment, various dispersion treatment machines such as a bead mill disperser, an ultrasonic disperser, a high-speed stirring disperser, and a high-pressure disperser can be applied, but a bead mill disperser can be preferably used.
Examples of the beads used in the bead mill disperser include zirconia beads and glass beads, but zirconia beads can be preferably used. The bead diameter used is preferably small, and more preferably within a range of 0.1 mm or less and 0.001 mm or more.

  In the case of producing a thermoplastic resin composition using a melt-kneading method, one or more kinds of gases selected from the inert gases nitrogen, helium, neon, argon, krypton, and xenon are used. It is preferable to be performed in an atmosphere of a mixed gas of the above, and even if it is a general gas such as carbon dioxide gas, ethylene gas, and hydrogen gas, as long as it is a gas that is not reactive with the material to be kneaded, the above-mentioned It may be used by mixing with an inert gas.

When producing a thermoplastic resin composition using the above-described melt-kneading method, it is preferable to eliminate residual oxygen as much as possible in the reaction system in the melt-kneading apparatus, but it is adsorbed to the thermoplastic resin or inorganic fine particles. It is difficult to completely eliminate the effects including oxygen.
Therefore, the amount of oxygen in the reaction system is preferably 1% or less, and more preferably 0.2% or less. This is because coloring occurs at the same time as the resin deteriorates due to the oxidation reaction with oxygen.

In addition, in the process for producing the resin composition described above, various additives may be added alone or in combination as necessary.
In this case, the additives include antioxidants, light stabilizers, heat stabilizers, weather stabilizers, stabilizers such as UV absorbers and near infrared absorbers, lubricants, resin modifiers such as plasticizers, soft weight, etc. Examples thereof include an anti-turbidity agent such as a coalescence, an alcoholic compound, a coloring agent such as a dye or a pigment, other antistatic agents, a flame retardant, and the like. They may be used alone or in combination.

  Among the additives described above, examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc., and phenolic antioxidants, particularly alkyl-substituted phenolic antioxidants. Are preferably used. By blending these antioxidants, it is possible to prevent lens coloring and strength reduction due to oxidative degradation during molding without lowering transparency, heat resistance, and the like.

  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 not impairing 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 of the thermoplastic material.

  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.

  In addition, the phosphorus antioxidant is not particularly limited as long as it is a substance 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) ) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and the like, and 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl- Di-tridecyl phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C1 -C15) 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.

  Further, as the sulfur-based antioxidant, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3- Thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Etc.

  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 thermoplastic resin composition may be blended with a compound having a minimum glass transition temperature of 30 ° C. or less. Thereby, it is possible to prevent the occurrence of white turbidity in an environment of high temperature and high humidity over a long period of time by suppressing deterioration of various properties such as transparency, heat resistance and mechanical strength.

  Among the additives mentioned above, examples of the light-resistant stabilizer include benzophenone-based light-resistant stabilizer, benzotriazole-based light-resistant stabilizer, hindered amine-based light-resistant stabilizer, and the like, such as lens transparency and coloring resistance. From the viewpoint, it is preferable to use a hindered amine light-resistant stabilizer (HALS). As such HALS, those having a low molecular weight, medium molecular weight and high molecular weight can be appropriately selected.

  As HALS having a relatively small molecular weight, LA-77 (manufactured by Asahi Denka), Tinuvin 765 (manufactured by CSC), Tinuvin 123 (manufactured by CSC), Tinuvin 440 (manufactured by CSC), Tinuvin 144 (manufactured by CSC), Hostavin N20 (manufactured by Hoechst), etc. Medium molecular weights such as LA-57 (Asahi Denka), LA-52 (Asahi Denka), LA-67 (Asahi Denka), LA-62 (Asahi Denka), etc., which have a higher molecular weight As LA-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) , CyasorbUV-334 (Manufactured by Cytec), (manufactured by Cytec) CyasorbUV-3529, and the like Uvasil299 (manufactured by GLC).

  In addition, when producing a molded object, it is preferable that low molecular weight or medium molecular weight HALS is used. On the other hand, when preparing a film-like composite material, it is preferable to use high molecular weight HALS.

The thermoplastic resin composition produced by the method described above contains a volatile substance having volatility.
As the volatile substance in the present embodiment, the dispersion medium of inorganic fine particles, the surface treatment agent, the dispersion medium of the thermoplastic resin, the monomer as the raw material of the thermoplastic resin, the polymerization start used in the polymerization reaction of the thermoplastic resin And volatile substances contained in various additives and the like. In addition to the various volatile substances described above, volatile substances are also contained in substances generated due to the decomposition reaction of the thermoplastic resin or inorganic fine particles at high temperatures.

  Further, the volatile substance in the present embodiment is such that the ratio of the volatilization amount with respect to the entire composition when the thermoplastic resin composition containing the volatile substance is heated at a temperature of 250 ° C. for 2 hours is 2% or less. Yes. This is because when the ratio of the volatilization amount to the whole composition is 2% or more, the strength of the thermoplastic resin composition is extremely lowered, and deformation and thermal expansion are likely to occur, that is, the heat resistance stability is deteriorated. Because it does.

  The volatile substance in the present embodiment is such that the ratio of the volatilization amount with respect to the entire composition when the thermoplastic resin composition containing the volatile substance is heated at a temperature of 250 ° C. for 2 hours is 2% or less. Is preferable, and it is more preferable that it is 0.5% or less.

Of the volatile substances, it is preferable to react the silane-based and titanium-based surface treatment agents and the monomer used as a raw material for the thermoplastic resin so that unreacted substances do not remain as much as possible.
Further, as the volatile substance, it is preferable that the liquid substance is as small as possible in the use temperature range of the optical element. This is because a substance such as a plasticizer that exists in a liquid state at room temperature and contains a large amount of unreacted substances even at 250 ° C. has a thermophysical property even when volatile substances are reduced. This is because the improvement effect is suppressed.

  As a method for quantifying volatile substances, a certain amount of sample is stored at a temperature of 250 ° C. under nitrogen, and an apparatus in which volatile substances are captured by a cold trap is used, based on a purge and trap method. Done.

In addition, it is preferable to use the sample of the state where the thickness of the thermoplastic resin composition is 1 mm or less and the volatilization of the volatile substance proceeds rapidly.
In addition, the quantification method of the volatile substance in the present embodiment is not particularly limited. For example, the volatile substance is volatilized by measuring the weight loss by heating the thermoplastic resin composition. A method of calculating the quantity may be used.

  Various molded products can be obtained by molding the thermoplastic resin composition as described above. Under the present circumstances, the thermoplastic resin composition shape | molded may consist of a mixture of a thermoplastic resin and various additives other than the case where it consists only of a thermoplastic resin.

  The molding method is not particularly limited, but the molding method is not particularly limited, but from the viewpoint of characteristics such as low birefringence, mechanical strength and dimensional accuracy in the molded product. The melt molding method is preferable. Examples of the melt molding method include commercially available press molding, commercially available extrusion molding, and commercially available injection molding. From the viewpoint of productivity, injection molding is preferable.

  The molding conditions are appropriately selected according to the purpose of use or molding method. For example, as the temperature of the resin composition in injection molding, an appropriate fluidity is imparted to the resin at the time of molding to reduce the sink of the molded product. From the viewpoints of prevention of distortion, generation of silver streak due to thermal decomposition of the resin, and effective prevention of yellowing of the molded product, it is preferably within a range of 150 ° C to 400 ° C, and 200 ° C to 350 ° C. It is more preferable that it is in the range of 200 ° C to 330 ° C.

  Furthermore, the optical resin lens is preferably negative in the AMES test. This is because a positive result in the AMES test may impair the health of the user, increase the environmental load, reduce the material stability, and the like.

Furthermore, the molded product in the present embodiment can be used in various forms such as a spherical shape, a rod shape, a plate shape, a columnar shape, a tubular shape, a tube shape, a fiber shape, a film shape, or a sheet shape. Moreover, since it is excellent in low birefringence, transparency, mechanical strength, heat resistance, low water absorption, etc., it can be applied to various optical components.
As a specific application 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 or a CD-ROM , WORM (recordable optical disc), MO (rewritable optical disc; magneto-optical disc), MD (mini disc), DVD (digital video disc) and other optical disc pickup lens; laser beam printer fθ lens, sensor lens And a laser scanning system lens such as a camera finder system prism lens.
Other optical uses 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 the above-described molded products, the thermoplastic resin composition of the present embodiment is suitably used as an optical element such as a pickup lens that requires low birefringence and a laser scanning system lens. An optical pickup device 1 using an optical element formed by an object will be described.
Here, FIG. 1 is a schematic diagram showing the internal structure of the optical pickup device 1.

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 L1, is collimated to infinite parallel light through the collimator 3, and then passes through the beam splitter 4 to pass through the quarter-wave plate 5. To Penetrate. Further, after passing through the diaphragm 6 and the objective lens 7, a condensed spot is formed on the information recording surface D ₂ via the protective substrate D ₁ of the optical disc D.

The light that forms the condensed spot is modulated by the information pits on the information recording surface D ₂ of the optical disc D and reflected by the information recording surface D ₂ . Then, the reflected light is sequentially transmitted through the objective lens 7 and the diaphragm 6, the polarization direction is changed by the quarter wavelength plate 5, and the reflected light 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.

Next, an example is given and the thermoplastic resin composition and optical element in this embodiment are demonstrated.
[Example 1]
First, a method for producing the inorganic fine particles 1, 2, 3 will be described.
Silica fine particle powder (manufactured by Nippon Aerosil Co., Ltd .: RX300, primary particle size 7 nm) treated with hexamethyldisilazane (hereinafter, HMDS), which is a silane-based surface treatment agent, is dried at a temperature of 200 ° C. for 24 hours before kneading. The inorganic fine particles thus obtained were stored in a nitrogen atmosphere and designated as “inorganic fine particles 1”.
In addition, silica fine particle powder (manufactured by Nippon Aerosil Co., Ltd .: RX50, primary particle size 40 nm) treated with HMDS was dried at a temperature of 200 ° C. for 24 hours before kneading and stored in a nitrogen atmosphere, and the resulting inorganic The fine particles were designated as “inorganic fine particles 2”.
Further, untreated silica fine particle powder (manufactured by Nippon Aerosil Co., Ltd .: A300, primary particle size 7 nm) was designated as “inorganic fine particle 3”.

Next, a manufacturing method of each sample 1 to 10 will be described.
First, a method for manufacturing Sample 1 will be described.
20 parts of PMMA (Poly (Methyl Methacrylate)) resin (manufactured by Mitsubishi Rayon: Acrypet VH) is dissolved in 80 parts of methyl isobutyl ketone at a temperature of 100 ° C., and the inorganic fine particles 1 and the entire thermoplastic resin composition are dissolved. The amount of the inorganic fine particles 1 added was adjusted so that the weight ratio was 50%, and mixed with the solution. Thereafter, a drying process is performed at a temperature of 150 ° C. At this time, a sample containing a predetermined amount of volatile substances was prepared by adjusting the drying time.
The sample thus obtained was designated as “Sample 1” and hot-pressed at a temperature of 120 ° C. so as to have a thickness of 1 mm.

Next, a method for manufacturing Samples 2 and 3 will be described.
In the method for preparing Sample 1, a sample was prepared by the same method except that the drying time was changed and the amount of volatile substances contained in the sample was changed.
The samples thus obtained were designated as “Sample 2” and “Sample 3”, and were hot-pressed at a temperature of 120 ° C. to form a thickness of 1 mm.

Next, a method for manufacturing Samples 4, 5, 6, and 7 will be described.
In the preparation method of Sample 1, the addition amount of the inorganic fine particles 1 was changed so that the weight ratio of the inorganic fine particles 1 to the entire thermoplastic resin composition was 5%, 20%, 70%, and 95%, and the drying time Each sample was produced by the same method except that the amount of volatile substances contained in the sample was changed.
Each sample thus obtained was designated as “Sample 4”, “Sample 5”, “Sample 6”, and “Sample 7”, and hot-pressed at a temperature of 120 ° C. to obtain a thickness of 1 mm. Molded as follows.
However, since the sample 7 could not obtain a smooth flat surface by hot pressing, a smooth flat surface was obtained by polishing the surface.

Next, a method for manufacturing Samples 8 and 9 will be described.
In the preparation method of Sample 1, the inorganic fine particles to be added are changed to inorganic fine particles 2 and 3, respectively, and the drying time is changed to change the amount of volatile substances contained in the sample. A sample was prepared.
The samples thus obtained were designated as “Sample 8” and “Sample 9”, respectively, and were hot-pressed at a temperature of 120 ° C. to form a thickness of 1 mm.

Next, a method for manufacturing the sample 10 will be described.
In the preparation method of Sample 1, a sample was prepared by the same method except that the inorganic fine particles were not added and the drying time was changed to change the amount of volatile substances contained in the sample.
The sample thus obtained was designated as “Sample 10” and hot-pressed at a temperature of 120 ° C. so as to have a thickness of 1 mm.

Next, an evaluation method for each resin molded sample will be described.
The measurement items include a total of three items, ie, light transmittance, linear expansion coefficient, and volatile substance amount. Based on these measurement results, evaluation was performed on each resin molded sample.
Hereinafter, the details of the measurement method for each item will be described.

First, a method for measuring light transmittance will be described.
Using a spectrophotometer (manufactured by Shimadzu Corporation: UV-3150), the light transmittance at a wavelength of 405 nm in the thickness direction (1 mm thickness) of the molded body was measured, and “light transmittance (%)” is shown in Table 2 below. Indicated.
Here, the measurement method of the light transmittance in a present Example was based on the method as described in ASTM D1003.

Next, a method for measuring the linear expansion coefficient will be described.
Using a measuring device (manufactured by SII Nano Technology Co., Ltd .: EXSTAR6000 TMA), the temperature is changed within a range of 40 ° C. to 80 ° C., and based on the dimensional change of the thickness dimension of the sample before and after the temperature change. The linear expansion coefficient was measured and shown as “Linear expansion coefficient (/ K)” in Table 2 below.

Finally, a method for measuring the amount of volatile substances will be described.
After each sample was stored at a temperature of 250 ° C. for 2 hours under a nitrogen stream, the amount of volatile substances was calculated based on the change in weight before and after storage, and the following table is shown as “Amount of Volatile Substances (%)”. It was shown in 2.

  As a result, Samples 1, 2, 4, and 5 in which the amount of volatile substances generated when heated at a temperature of 250 ° C. for 2 hours is 2% or less with respect to the entire thermoplastic resin composition and containing inorganic fine particles. , 6, 8, 9, and 10 show a linear expansion as compared with Sample 3 in which the amount of volatile substances generated is 2% or more of the entire thermoplastic resin composition and Sample 10 that does not contain inorganic fine particles. It was confirmed that the coefficient value was small, that is, the heat stability was excellent.

  Samples 1, 2, 5, and 6 in which the inorganic fine particles contained are subjected to a surface treatment with a silane-based surface treatment agent are compared with Sample 9 that is not subjected to a surface treatment with a silane-based surface treatment agent. Then, it was confirmed that the light transmittance is high, that is, the transparency is excellent.

  Furthermore, Samples 1, 2, 5, and 6 in which the content of the inorganic fine particles contained in the entire thermoplastic resin composition is within a range of 10 to 90% are Samples 4 and 7 that are outside the range of 10 to 90%. As a comparison, it was confirmed that Sample 4 had a large coefficient of linear expansion and deteriorated heat resistance stability. On the other hand, it was confirmed that Sample 7 had a very small linear expansion coefficient and excellent heat stability, but had a small light transmittance and deteriorated transparency.

  Furthermore, Samples 1, 2, 5, and 6 in which the volume average dispersed particle diameter of the inorganic fine particles contained is 30 nm or less have a smaller value of the linear expansion coefficient than Sample 8 whose volume average dispersed particle diameter is larger than 30 nm. It was confirmed that the value of light transmittance was large, that is, heat resistance stability and light transmittance were excellent.

[Example 2]
First, the inorganic fine particles 4 will be described.
Untreated alumina powder (manufactured by Daimei Chemical Co., Ltd .: TM-300, primary particle size: 7 nm) was designated as “inorganic fine particles 4”.

Next, a method for manufacturing each of the samples 11 to 14 will be described.
First, a method for manufacturing the sample 11 will be described.
A solution in which 10 parts of cyclohexylmethyldimethoxysilane (manufactured by Toray Dow Chemical Co., Ltd .: SZ-6187) was dissolved in toluene (total 200 parts) was added to 100 parts of the inorganic fine particles 4 and stirred to prepare a slurry liquid. Then, using a twin-screw extruder (manufactured by Toyo Seiki Seisakusho: Labo Plast Mill), the cyclic olefin resin (manufactured by Nippon Zeon: ZEONEX 340R) was melted, and each slurry was added and then kneaded. Further, after devolatilization at an appropriate temperature while kneading, the sample was extruded from a strand die, cut and pelletized to prepare a sample containing a predetermined amount of a volatile substance.
The sample thus obtained was designated as “Sample 11”, and was hot-pressed at a temperature of 120 ° C. to form a thickness of 1 mm.

Next, a method for manufacturing Samples 12, 13, and 14 will be described.
In the method for preparing Sample 11 described above, the organic solvent for dissolving 10 parts of cyclohexylmethyldimethoxysilane was changed to xylene, cyclohexane and tetrahydrofuran, respectively, and the volatilization contained in the sample was changed by changing the devolatilization temperature in the kneading step. A sample was prepared in the same manner except that the amount of the active substance was changed.
The samples thus obtained were designated as “Sample 12”, “Sample 13”, and “Sample 14”, respectively, and were hot-pressed at a temperature of 120 ° C. to form a thickness of 1 mm.

  Thereafter, the light transmittance, the linear expansion coefficient, and the amount of volatile substances in each of the samples 11, 12, 13, and 14 were measured by the same method as in Example 1 described above, and are shown in Table 3 below. In addition, the samples 11, 12, 13, and 14 were evaluated based on the measurement results in the respective measurement items.

  As a result, the amount of volatile substances generated when heated at a temperature of 250 ° C. for 2 hours was 2% or less with respect to the entire thermoplastic resin composition, and Sample 13 in which the cyclic olefin resin was contained in the thermoplastic resin. , 14 is slightly larger in light transmittance than samples 11 and 12 in which the cyclic olefin resin is not contained in the thermoplastic resin, but has a small linear expansion coefficient, heat stability and light resistance. It was confirmed that the transmittance was excellent.

  As described above, according to the thermoplastic resin composition and the optical element in the present embodiment, the ratio of the volatilization amount of the volatile substance at the time when the thermoplastic resin composition is heated at a temperature of 250 ° C. for 2 hours is the total composition. On the other hand, when it is 2% or less, it is possible to prevent a significant drop in strength, deformation and thermal expansion, and to improve the light transmittance, thereby improving heat stability and transparency. Improvements can be made.

It is a schematic diagram which shows an example of the pick-up apparatus for optical discs which applied the optical element which concerns on this invention as an objective lens.

Explanation of symbols

  7 Objective lens

Claims (6)

In the thermoplastic resin composition containing the thermoplastic resin and inorganic fine particles,
Containing a volatile substance having volatility, which is added in the production process or generated by a decomposition reaction of the thermoplastic resin or inorganic fine particles in the production process;
The said volatile substance is a thermoplastic resin composition characterized by the ratio of the volatilization amount with respect to the whole composition at the time of heating for 2 hours at the temperature of 250 degreeC being 2% or less.   The thermoplastic resin composition according to claim 1, wherein the inorganic fine particles contain a silane-based or titanium-based surface treatment agent that has been surface-treated with at least one surface treatment agent.   The thermoplastic resin composition according to claim 1 or 2, wherein the inorganic fine particles have a content of 10 to 90% with respect to the entire composition.   The thermoplastic resin composition according to any one of claims 1 to 3, wherein the inorganic fine particles have a volume average dispersed particle diameter of 30 nm or less.   The thermoplastic resin composition according to any one of claims 1 to 4, wherein the thermoplastic resin contains a cyclic olefin resin.   An optical element formed by using the thermoplastic resin composition according to any one of claims 1 to 5.

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