Birefringence reducer and thermoplastic resin composition

Abstract

A birefringence reducer, which is an additive for reducing the birefringence of a resin, comprises an organosiloxane compound having an aromatic group.

Description

Technical Field

[0001] This invention relates to birefringence reducers and thermoplastic resin compositions, and more specifically, to birefringence reducers that reduce the birefringence of resins and thermoplastic resin compositions containing the same that reduce birefringence. Background Technology

[0002] Optical lenses formed from optically transparent resins can be mass-produced using injection molding and have the advantage of being easy to manufacture aspherical lenses, making them suitable for use as lenses in cameras, telescopes, and projectors. Examples of optically transparent resins include thermoplastic resins, such as polycarbonate resins using 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) as a raw material, polymethyl methacrylate, or amorphous polyolefins.

[0003] When forming optical components from optical transparent resin, one of the important optical properties that must be considered is birefringence. That is, it is not preferable for optical transparent resins to have high birefringence. Especially in high-end cameras, liquid crystal displays, projectors, etc., the presence of lenses with high birefringence in the optical path will adversely affect image quality and signal reading performance. Therefore, it is strongly required to use optical transparent resins with birefringence that are minimized as much as possible.

[0004] However, polycarbonate resins, for example, made from bisphenol A have advantages such as high refractive index and high heat resistance, but also disadvantages such as high birefringence.

[0005] For the requirement of reducing birefringence, it is known to use polycarbonate resins with bisphenols of a specific structure as raw materials. For example, Patent Document 1 discloses a special polycarbonate copolymer with low birefringence formed by copolymerizing spirocyclic bisindane bisphenol and bisphenol A.

[0006] However, this special resin is not a general-purpose resin, and its properties (mechanical properties) and molding conditions are special. Moreover, its use is limited in terms of price.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 06-313035 Summary of the Invention

[0010] The problem the invention aims to solve

[0011] The present invention was made in view of the above circumstances, and its object (problem) is to provide a birefringence reducer that can reduce birefringence simply by being mixed with an optical transparent resin, and a thermoplastic resin composition containing the same.

[0012] Solution for solving the problem

[0013] In order to solve the above-mentioned objective (problem), the inventors conducted repeated and in-depth research and found that certain organosiloxane compounds can reduce the birefringence of resins.

[0014] This invention relates to the following birefringence reducers, thermoplastic resin compositions, and molded articles.

[0015] 1. A birefringence reducer, which is an additive for reducing the birefringence of a resin, comprising an organosiloxane compound having an aromatic group.

[0016] 2. The birefringence reducer according to 1 above, wherein the organosiloxane compound having an aromatic group is a cyclic organosiloxane compound represented by the following general formula (1).

[0017]

[0018] [In formula (1), R represents an aryl group with 6 to 14 carbon atoms that is arbitrarily chosen to have substituents, and n is an integer from 1 to 5.]

[0019] 3. The birefringence reducer according to 2 above, wherein R in formula (1) contains phenyl or naphthyl.

[0020] 4. A thermoplastic resin composition comprising, wherein the birefringence reducer described in any one of 2 to 3 above is incorporated into the thermoplastic resin.

[0021] 5. The thermoplastic resin composition according to 4 above, wherein the thermoplastic resin is a thermoplastic resin having an aromatic ring in the main chain and having positive intrinsic birefringence.

[0022] 6. The thermoplastic resin composition according to 4 or 5 above, wherein the thermoplastic resin is an aromatic polycarbonate resin or an aromatic polyester resin with a glass transition temperature of 160°C or higher.

[0023] 7. The thermoplastic resin composition according to 6 above, wherein the aforementioned aromatic polycarbonate resin is a resin containing 70 mol% or more of the structural unit shown in formula (2) in all structural units except for the terminal groups.

[0024]

[0025] 8. The thermoplastic resin composition according to any one of 4 to 7 above, wherein the content of the birefringence reducer is more than 2 parts by weight and less than 15 parts by weight relative to 100 parts by weight of the thermoplastic resin.

[0026] 9. The thermoplastic resin composition according to any one of 4 to 8 above has reduced birefringence.

[0027] 10. A molded article formed from any one of the thermoplastic resin compositions described in any one of 4 to 9 above.

[0028] 11. The molded body according to 10 above is an optical molded body.

[0029] 12. The molded body according to 10 or 11 above is an optical lens.

[0030] The effects of the invention

[0031] The birefringence reducer of the present invention can reduce birefringence simply by being blended into a resin. The birefringence of the thermoplastic resin composition in which it is blended is reduced without reducing the transparency (transmittance) of the thermoplastic resin itself. Furthermore, it exhibits excellent heat aging resistance, eliminates mold contamination issues during molding, and provides excellent flowability (formability). Therefore, the resulting molded article is suitable as an optical molded article, particularly for optical lenses in SLR cameras, digital cameras, camcorders, portable telephones with cameras, thin films with lenses, telescopes, binoculars, microscopes, or projectors.

[0032] The organosiloxane compounds with aromatic rings used in this invention possess polarization anisotropy that can eliminate the polarization anisotropy of the resin and thus eliminate birefringence. In particular, the cyclic organosiloxane compounds represented by the aforementioned general formula (1) have a structure in which the aromatic ring of the aryl group as R is vertically erected relative to the cyclic plane of the cyclic organosiloxane. On the other hand, it is believed that the aromatic rings oriented in a planar manner in the molecular chain direction, especially in thermoplastic resins, eliminate the polarization anisotropy of both sides, thereby effectively eliminating birefringence. Detailed Implementation

[0033] The following provides a detailed description of the birefringence reducer of the present invention and the various components used in the resin composition constituting the thermoplastic resin composition.

[0034] It should be noted that in this specification, when “~” is used to express a range by enclosing the values ​​before and after it with numerical or physical property values, it refers to the range including the values ​​before and after it.

[0035] [Birefringence reducer]

[0036] The birefringence reducer of the present invention comprises an organosiloxane compound having an aromatic group.

[0037] Organosiloxane compounds having aromatic groups, such as phenyl or naphthyl groups, can be any type of cyclic or linear organosiloxane compounds, with cyclic organosiloxane compounds being preferred.

[0038] The linear organosiloxane compound having aromatic groups is a linear organosiloxane bonded with aryl-substituted siloxanes, preferably an organosiloxane composed of phenyl-substituted siloxane units, or siloxane units substituted with alkyl groups such as methyl, ethyl, propyl, and butyl, and may contain alkyl-disubstituted siloxane units, such as dimethylsiloxane units, diethylsiloxane units, ethylmethylsiloxane units, etc.

[0039] Cyclic organosiloxane compounds, which are preferred as organosiloxane compounds having aromatic groups, are particularly preferred examples of cyclic organosiloxane compounds represented by the following general formula (1).

[0040]

[0041] [In formula (1), R represents an aryl group with 6 to 14 carbon atoms that is arbitrarily chosen to have substituents, and n is an integer from 1 to 5.]

[0042] R is an aryl group having 6 to 14 carbon atoms, optionally with substituents.

[0043] Here, examples of substituents include alkyl groups having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, n-butyl, tert-butyl, etc., or phenyl, phenyl groups having an alkyl group (such as the alkyl groups mentioned above).

[0044] Aryl groups with 6 to 14 carbon atoms can be exemplified by phenyl, naphthyl, etc., with phenyl being the preferred choice.

[0045] Specific examples of R include phenyl, toluyl, dimethylphenyl, naphthyl, and biphenyl.

[0046] The cyclic organosiloxane compound represented by general formula (1) may have only one aryl group or may have two or more different aryl groups.

[0047] n is an integer from 1 to 5, preferably an integer from 2 to 4, more preferably 2 or 3, and especially preferably 3.

[0048] Specific examples of cyclic organosiloxane compounds represented by general formula (1) include octaphenylcyclotetrasiloxane, octanaphthylcyclotetrasiloxane, octabenzyloylcyclotetrasiloxane, octabiphenylcyclotetrasiloxane, hexaphenylcyclotrisiloxane, decaphenylcyclopentasiloxane, etc., with octaphenylcyclotetrasiloxane being particularly preferred.

[0049] Cyclic organosiloxane compounds can be used alone or in combination of two or more different compounds.

[0050] [Thermoplastic resin composition]

[0051] By incorporating the above-mentioned birefringence reducer into the resin, a resin composition with reduced birefringence compared to that before incorporation is formed.

[0052] Thermoplastic resins are preferred as the resin, and thermoplastic resins with aromatic rings in the main chain tend to have particularly high birefringence, and are therefore preferred. Furthermore, thermoplastic resins with positive intrinsic birefringence are preferred because the birefringence reducer of the present invention has negative intrinsic birefringence, thus resulting in a greater birefringence reduction effect. Thermoplastic resins with aromatic rings in the main chain and positive intrinsic birefringence are particularly preferred.

[0053] As thermoplastic resins, polycarbonate resins or polyester resins are preferred examples.

[0054] [Polycarbonate resin]

[0055] There are no restrictions on the type of polycarbonate resin; all can be mixed with birefringence reducers. Aromatic polycarbonate resins with aromatic rings in the main chain are preferred from the viewpoint of having a greater birefringence reduction effect.

[0056] Aromatic polycarbonate resins are aromatic polycarbonate polymers obtained by reacting aromatic hydroxyl compounds with phosgene or carbonic acid diesters. Aromatic polycarbonate polymers may have branched chains. There are no particular limitations on the manufacturing method of aromatic polycarbonate resins; conventional methods such as the phosgene process (interfacial polymerization) and the melt process (transesterification) can be used.

[0057] Representative examples of aromatic dihydroxy compounds include 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 4,4-bis(4-hydroxyphenyl)heptane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxybiphenyl, 3,3',5,5'-tetramethyl-4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) ketone, etc.

[0058] The above-mentioned aromatic dihydroxy compounds can be used alone or in combination of two or more.

[0059] Among the aforementioned aromatic dihydroxy compounds, 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) and 2,2-bis(4-hydroxy-3-methylphenyl)propane (i.e., bisphenol C) are preferred as they form polycarbonate resins with high birefringence. However, 1,1-bis(4-hydroxyphenyl)-1-phenylethane (i.e., bisphenol AP) and other compounds with reduced birefringence, or any of the above compounds that also exhibit a birefringence-reducing effect, are also preferred.

[0060] Polycarbonate resins having structural units derived from 1,1-bis(4-hydroxyphenyl)-1-phenylethane, i.e., bisphenol AP, of the following formula (2) are preferred from the viewpoint of exhibiting high heat resistance.

[0061]

[0062] In the transesterification polymerization, diesters are used as monomers instead of phosgene. Examples of diesters using aromatic dihydroxy compounds include substituted diaryl carbonates such as diphenyl carbonate and dimethyl carbonate. These diesters can be used alone or in mixtures of two or more.

[0063] The viscosity-average molecular weight (Mv) of the polycarbonate resin is preferably in the range of 10,000 to 50,000, more preferably 45,000 or less, even more preferably 40,000 or less, and particularly preferably 38,000 or less. In the case of molded articles for optical applications, it is preferably 10,000 to 30,000. With a viscosity-average molecular weight in this range, the flowability (processability), color, and mechanical strength are excellent, which is suitable for molded articles for optical applications.

[0064] It should be noted that two or more aromatic polycarbonate resins with different viscosity-average molecular weights can be mixed for use. In this case, polycarbonate resins with viscosity-average molecular weights outside the preferred range described above can be mixed.

[0065] It should be noted that the viscosity-average molecular weight Mv of polycarbonate resin refers to the intrinsic viscosity [η] (unit: dl / g) at 25°C, calculated using dichloromethane as a solvent and an Ubbelohde viscometer, derived from Schnell's viscosity formula, η = 1.23 × 10⁻⁶. -4 Mv 0.83 The calculated value. Additionally, intrinsic viscosity [η] refers to the specific viscosity [η] measured at various solution concentrations [C] (g / dl). sp The value is calculated using the following formula.

[0066]

[0067] The polycarbonate resin is preferably an aromatic polycarbonate resin with a glass transition temperature of 160°C or higher. Higher heat resistance can be achieved by having a glass transition temperature of 160°C or higher. A glass transition temperature of 165°C or higher is more preferred, and 170°C or higher is particularly preferred.

[0068] It should be noted that the glass transition temperature of polycarbonate resin is a value obtained by differential scanning calorimetry (DSC) under the following conditions according to JIS K7122.

[0069] Measurement start temperature: 25℃

[0070] Heating rate: 10℃ / minute

[0071] Temperature reached: 300℃

[0072] Cooling rate: 10℃ / minute

[0073] The polycarbonate resin can be not only unused resin, but also polycarbonate resin recycled from used products (so-called material recycling polycarbonate resin), or polycarbonate resin made from materials that have been chemically decomposed and returned to the raw materials (so-called chemical recycling polycarbonate resin). It is preferable to contain both unused resin and recycled resin, and it may also contain recycled polycarbonate resin. The proportion of recycled polycarbonate resin in the polycarbonate resin is preferably 40% or more, 50% or more, 60% or more, or 80% or more, and preferably 100% recycled polycarbonate resin.

[0074] [Polyester resin]

[0075] There are no restrictions on the type of polyester resin, and all can be mixed with the birefringence reducer of the present invention. Aromatic polyester resins with aromatic rings in the main chain are preferred from the viewpoint that they mostly have positive birefringence and have a large birefringence reduction effect.

[0076] Aromatic polyester resins with aromatic rings in their main chain include condensation polymers formed from aromatic dicarboxylic acids and diols.

[0077] As a dicarboxylic acid, an aromatic dicarboxylic acid is preferred, and examples include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-benzophenone dicarboxylic acid, 4,4'-diphenoxyethane dicarboxylic acid, and 4,4'-diphenyl sulfone dicarboxylic acid.

[0078] Examples of diols include ethylene glycol, 1,3-propanediol, diethylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, neopentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,6-cyclohexanediethanol, tricyclohexanediethanol, polyoxyethylene glycol, and polyoxypropylene glycol, among other aliphatic diols. Examples of aromatic diols include 1,2-diphenylethane-1,2-diol, 1,1,2,2-tetraphenylethane-1,2-diol, and benzene-1,2-, -1,3-, and -1,4-diethanol. Additionally, examples of bisphenols include bisphenol A, bisphenol F, bisphenol S, bisphenol AP, tetramethylbisphenol A, and 4,4'-dihydroxydiphenyl-2,2-butane.

[0079] They can be used individually or in combination of two or more.

[0080] From the viewpoint of transparency for optical molded articles, amorphous polyester resins are preferred as polyester resins. The amorphous nature of an amorphous polyester resin refers to the absence of a clearly defined melting point when heated at a rate of 10°C / min using a differential calorimeter.

[0081] The intrinsic viscosity IV of the polyester resin is preferably 0.3 to 1.5 dl / g, more preferably 0.4 to 1.2 dl / g.

[0082] It should be noted that the intrinsic viscosity IV of the polyester resin is the value obtained by measuring in a 1:1 (mass ratio) mixed solvent of tetrachloroethane and phenol at 30°C.

[0083] When the birefringence reducer of the present invention is incorporated into a thermoplastic resin, its content is preferably more than 2 parts by weight and less than 15 parts by weight, more preferably more than 2.3 parts by weight and less than 13 parts by weight, relative to 100 parts by weight of the thermoplastic resin. By setting this content, the effect of reducing birefringence is fully manifested, the flowability (formability) of the resin composition is also sufficient, the heat aging resistance is excellent, and mold contamination will not become a problem.

[0084] [Additives, etc.]

[0085] The resin composition may contain additives, such as stabilizers, release agents, flame retardants, flame retardant additives (anti-drip agents), ultraviolet absorbers, optical brighteners, antistatic agents, plasticizers, compatibilizers, etc. These additives or other resins may be blended in one or more forms.

[0086] [Stabilizer]

[0087] The resin composition preferably contains a stabilizer, and the stabilizer is preferably a phosphorus-based stabilizer or a phenol-based stabilizer.

[0088] As a phosphorus-based stabilizer, any known stabilizer can be used. Specific examples include oxyacids of phosphorus such as phosphoric acid, phosphonic acid, phosphorous acid, hypophosphonic acid, and polyphosphoric acid; acidic pyrophosphate metal salts such as sodium acid pyrophosphate, potassium acid pyrophosphate, and calcium acid pyrophosphate; phosphates of Group 1 or Group 2B metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; organophosphate compounds, organophosphonite compounds, and organophosphonate compounds, with organophosphonite compounds and organophosphate compounds being particularly preferred.

[0089] Examples of organophosphite compounds include triphenyl phosphite, tris(mononophenyl) phosphite, tris(monono / dinonophenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, monooctyl diphenyl phosphite, dioctyl monophenyl phosphite, monodecyl diphenyl phosphite, didecyl monophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, and 2,2-methylene bis(4,6-di-tert-butylphenyl)octyl phosphite.

[0090] Specifically, examples of such organophosphite compounds include "ADK STAB1178", "ADK STAB 2112", and "ADK STAB HP-10" manufactured by ADEKA, "JP-351", "JP-360", and "JP-3CP" manufactured by Jōhoku Chemical Industry Co., Ltd., and "Irgafos 168" manufactured by BASF.

[0091] As organophosphate compounds, organophosphate metal salts can also be suitably used. Specifically, examples include zinc salts of distearate phosphates and zinc salts of monostearate phosphates, mono- and di-stearate phosphates, etc.

[0092] Specifically, examples of such organophosphate metal salts include "JP-518Zn" manufactured by Johoku Chemical Industry Co., Ltd., and "AX-71" manufactured by ADEKA Co., Ltd.

[0093] It should be noted that phosphorus-based stabilizers can contain one type or two or more types in any combination and ratio.

[0094] The content of phosphorus-based stabilizers relative to 100 parts by weight of the thermoplastic resin is typically 0.001 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.03 parts by weight or more, and typically 1 part by weight or less, preferably 0.7 parts by weight or less, more preferably 0.5 parts by weight or less. If the content of the phosphorus-based stabilizer is less than the lower limit of the aforementioned range, the heat stabilization effect may become insufficient; if the content of the phosphorus-based stabilizer exceeds the upper limit of the aforementioned range, the effect reaches its limit, which may be uneconomical.

[0095] Examples of phenolic stabilizers include hindered phenolic antioxidants. Specific examples include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylidene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 2,4-dimethyl-6-(1-methylpentadecanyl)phenol, diethyl[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphate, 3,3',3”,5,5',5”-hexa-tert-butyl-a,a',a”-(mesene- 2,4,6-Trimethyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylene bis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, etc.

[0096] Among them, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferred.

[0097] Specifically, examples of such phenolic antioxidants include BASF's "Irganox 1010" and "Irganox 1076", and ADEKA's "ADK STAB AO-50" and "ADK STAB AO-60".

[0098] It should be noted that phenolic stabilizers can contain one type or two or more types in any combination and ratio.

[0099] The content of the phenolic stabilizer relative to 100 parts by weight of the thermoplastic resin is typically 0.001 parts by weight or more, preferably 0.01 parts by weight or more, and typically 1 part by weight or less, preferably 0.5 parts by weight or less. If the content of the phenolic stabilizer is less than the lower limit of the aforementioned range, its effect as a phenolic stabilizer may be insufficient; if the content of the phenolic stabilizer exceeds the upper limit of the aforementioned range, its effect reaches its limit, which may be uneconomical.

[0100] [Mold Release Agent]

[0101] The resin composition preferably contains a release agent. Known release agents commonly used in resins can be used as the release agent, preferably polyolefin compounds or fatty acid ester compounds.

[0102] Examples of polyolefin compounds include compounds selected from alkane waxes and polyethylene waxes, wherein the weight-average molecular weight is preferably 700 to 10,000, and more preferably 900 to 8,000.

[0103] Examples of fatty acid ester compounds include saturated or unsaturated monovalent or divalent aliphatic carboxylic acid esters, glycerol fatty acid esters, sorbitol fatty acid esters, and their partial saponifications. Among these, mono- or di-fatty acid esters composed of fatty acids having 11 to 28 carbon atoms, preferably 17 to 21 carbon atoms, and alcohols are preferred.

[0104] Examples of fatty acids include palmitic acid, stearic acid, hexanoic acid, decanoic acid, lauric acid, arachidic acid, docosanoic acid, tetracosanoic acid, ceric acid, beeswax acid, tritetracosanoic acid, linalic acid, adipic acid, and azelaic acid. Furthermore, fatty acids can be alicyclic.

[0105] Examples of alcohols include saturated or unsaturated monohydric or polyhydric alcohols. These alcohols may have substituents such as fluorine atoms or aryl groups. Among them, monohydric or polyhydric saturated alcohols with 30 or fewer carbon atoms are preferred, and aliphatic saturated monohydric or polyhydric alcohols with 30 or fewer carbon atoms are even more preferred. Here, aliphatic compounds also include alicyclic compounds.

[0106] Specific examples of the aforementioned alcohols include octanol, decanol, dodecyl alcohol, stearyl alcohol, behenol, ethylene glycol, diethylene glycol, glycerol, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentyl glycol, di(trimethylol)propane, and dipentaerythritol.

[0107] It should be noted that the ester compounds mentioned above may contain aliphatic carboxylic acids and / or alcohols as impurities, or they may be mixtures of multiple compounds.

[0108] Specific examples of fatty acid ester compounds include glyceryl monostearate, glyceryl monodocolate, glyceryl di(docolate), glyceryl-12-hydroxy monostearate, sorbitol monodocolate, pentaerythritol monostearate, pentaerythritol distearate, stearyl stearate, and ethylene glycol lignite.

[0109] The content of the release agent relative to 100 parts by weight of the thermoplastic resin is preferably 0.1 to 3 parts by weight, more preferably 0.2 to 2.5 parts by weight, and even more preferably 0.25 to 2 parts by weight. If it is less than 0.1 parts by weight, the surface properties are easily reduced due to poor demolding during melt molding. On the other hand, if it exceeds 3 parts by weight, the kneadability of the resin composition is easily reduced, and the surface of the molded body is prone to becoming cloudy.

[0110] [Flame retardant]

[0111] The resin composition of the present invention may also contain flame retardants.

[0112] Examples of flame retardants include organometallic salt flame retardants, phosphorus-based flame retardants, boron-based flame retardants, nitrogen-based flame retardants, halogen-based flame retardants, and antimony compounds.

[0113] However, when pursuing a resin composition with high transparency and low birefringence for optical moldings, it is preferable to have a low content of flame retardant. Even if an organometallic salt flame retardant is included as a flame retardant for transparency, its content is preferably less than 0.01 parts by weight, more preferably less than 0.005 parts by weight, relative to 100 parts by weight of the thermoplastic resin.

[0114] [Preparation of the resin composition]

[0115] There are no restrictions on the manufacturing method of the resin composition. Well-known methods for manufacturing thermoplastic resin compositions can be widely used. Examples include pre-mixing the resin and organosiloxane compound, along with other components to be mixed as needed, using various mixers such as roller mixers and Henschel mixers, and then melt-mixing them using mixers such as Banbury internal mixers, roller mixers, Brabender mixers, single-screw compounding extruders, twin-screw compounding extruders, and kneaders.

[0116] For resin compositions, various molded articles can be manufactured by molding the granules obtained from granulating the above-mentioned resin compositions using various molding methods. Alternatively, molded articles can be formed directly from resins melt-mixed using an extruder without going through the granulation process.

[0117] The resin composition of the present invention does not impair the transparency of the resin itself, greatly reduces birefringence, exhibits excellent heat aging resistance, and eliminates problems of flowability and mold contamination during molding. Therefore, preferred applications include optical molded bodies, specifically various lenses, such as lenses for cameras (SLR cameras, digital cameras, camcorders, thin films with lenses, etc.), telescopes, microscopes, projectors, optical measuring devices, portable telephone cameras, smartphone cameras, tablet cameras, vehicle cameras, action cameras, laptop PC cameras, dashcams, surveillance cameras, small cameras for drones, various optical discs, home televisions, personal computer monitors, vehicle monitors, smartphones, head-mounted displays, barcode readers, scanners, etc., panel components, thin films, etc.

[0118] Example

[0119] The present invention will be described in more detail below through embodiments. However, the present invention is not limited to or explained by the following embodiments.

[0120] The raw materials used in the following examples and comparative examples are shown in Table 1 below.

[0121] [Table 1]

[0122]

[0123] The above-mentioned bisphenol C aromatic polycarbonate (A5) was manufactured by the following manufacturing example 1.

[0124] <Manufacturing Example 1: Manufacturing of Bisphenol C Polycarbonate Resin (A5)>

[0125] 26.14 mol (6.75 kg) of 2,2-bis(3-methyl-4-hydroxyphenyl)propane (hereinafter referred to as "BPC") and 26.79 mol (5.74 kg) of diphenyl carbonate were added to a SUS reactor (10 liters in volume) equipped with a stirrer and a distillation condenser. After purging the reactor with nitrogen, the temperature was raised to 220°C in a nitrogen atmosphere over 30 minutes.

[0126] Next, the reaction solution in the reactor was stirred, and the molten reaction solution was injected with a concentration of 1.5 × 10⁻⁶ mol / L relative to 1 mole of BPC. -6Cesium carbonate (Cs₂CO₃) was added molarly as a catalyst for the transesterification reaction, and the mixture was stirred at 220°C under a nitrogen atmosphere to form a reaction solution for 30 minutes. Then, the pressure inside the reactor was reduced to 100 Torr over 40 minutes at the same temperature, and the reaction was continued for 100 minutes, resulting in the distillation of phenol. Next, the temperature inside the reactor was increased to 284°C while the pressure was reduced to 3 Torr over 60 minutes, distilling off approximately the total theoretical amount of phenol. Finally, the pressure inside the reactor was maintained at less than 1 Torr at the same temperature, and the reaction was continued for another 60 minutes to terminate the polycondensation reaction.

[0127] At this point, the mixer speed was 38 rpm, the temperature of the reaction liquid before the reaction was about to end was 289℃, and the stirring power was 0.75kW. Next, the molten reaction liquid was directly fed into a twin-screw extruder, and butyl p-toluenesulfonate in a molar amount of 4 times that of cesium carbonate was supplied from the first feed port of the twin-screw extruder to mix with the reaction liquid. Then, the reaction liquid was extruded in wire form through the die of the twin-screw extruder and cut with a cutter to obtain bisphenol C type polycarbonate resin (A5) granules.

[0128] (Examples 1-17, Comparative Examples 1-6)

[0129] [Preparation of Resin Composition Granules]

[0130] The polycarbonate resin and various additives listed in Table 1 are mixed in proportions (parts by mass) as shown in Table 2 and below. After mixing with a drum for 20 minutes, the mixture is then kneaded using a single-screw extruder with a vent hole (manufactured by TANABEPLASTICS MACHINERY CO.,LTD., “VS50-34V”) with a screw diameter of 50 mm. The mixture is then kneaded at a barrel temperature of 250℃~280℃ and a screw speed of 80 rpm. The extruded wire is then cut to produce granules.

[0131] After drying the granules obtained above at 120°C for 5 hours, they were injection molded using an injection molding machine (Sumitomo Heavy Industries, Ltd. "SE50DUZ") to produce test pieces with a thickness of 3 mm.

[0132] For injection molding conditions, when bisphenol A aromatic polycarbonate resin (A1, A2) or bisphenol C aromatic polycarbonate resin (A5) is present, the barrel temperature is 280℃ and the mold temperature is 80℃. When bisphenol AP aromatic polycarbonate resin (A3, A4) is present, the barrel temperature is set to 300℃ and the mold temperature to 100℃.

[0133] The following evaluations were performed on the obtained granules or test pieces.

[0134] [Glass transition temperature (Tg)]

[0135] For the resin composition granules obtained above, the glass transition temperature (Tg) was determined using a differential scanning calorimeter (DSC, Hitachi High-Tech Corporation "DSC7000X") based on JIS K7211 under the following conditions. The determination conditions are as described below.

[0136] Sample amount: 5 mg; Atmosphere: Nitrogen atmosphere; Silencing conditions: 10 degrees Celsius / minute

[0137] [Evaluation of birefringence]

[0138] Birefringence was evaluated using a large-range two-dimensional birefringence evaluation system (Photonic Lattice "WPA-200", measurement wavelength: 523 nm). The values ​​of the 3 mm thick test pieces obtained above were measured before and after annealing. Annealing was carried out for 3 hours at a temperature 20 °C lower than the Tg of each composition.

[0139] For the evaluation of birefringence, the value of the 3 mm thick test piece obtained in Comparative Example 1 before annealing was used as 100% (reference value) for evaluation.

[0140] [Total transmittance (%)]

[0141] For the 3mm thick test piece obtained above, the total transmittance (unit: %) was measured using a spectrophotometer (SH7000 manufactured by Nippon Denshoku Kogyo Co., Ltd.) based on JIS K7375.

[0142] [Mold Contamination Evaluation]

[0143] The adhesion of the resin composition granules obtained above to the mold after 500 injection molding cycles using an injection molding machine (Sumitomo Heavy Industries, Ltd. "SE7MII") at a barrel temperature of 270°C, a teardrop mold shape, and a mold temperature of 80°C is evaluated by the following visual criteria.

[0144] A: Almost no attached material was observed.

[0145] B; Observed attachments

[0146] C: Many attached substances were observed.

[0147] Liquidity Q value (unit: cm) 3 / s)]

[0148] After drying the resin composition granules obtained above at 120°C for 4 hours, the Q value (unit: cm) was measured using a flow tester (Shimadzu Corporation "CFT-500D") under the following conditions according to JIS K7210.3 / s).

[0149] Sample size: 1-2g, temperature: 280℃, load: 160kgf

[0150] <Evaluation of heat aging resistance (ΔYI)>

[0151] YI (initial YI) of a 3 mm thick test piece obtained by the above method was measured using an SH7000 manufactured by Nippon Denshoku Kogyo Co., Ltd.

[0152] The aforementioned test pieces were then subjected to 1000 hours of accelerated life testing using an ESPEC CORP. "EHS-221MD" device at 125°C, and the YI (YI after 1000 hours of treatment) was measured in the same manner.

[0153] Heat aging resistance is evaluated using the following formula ΔYI.

[0154] [YI after 1000 hours of treatment] - [YI after forming]

[0155] The evaluation results are shown in Table 2 and below. It should be noted that in the table, "real n" represents "example n" and "compare n" represents "comparative example n".

[0156] [Table 2]

[0157]

[0158] It should be noted that Comparative Example 3 and Example 7, due to the use of bisphenol C aromatic polycarbonate (A5) with low Tg, could not be aged at 125°C for 1000 hours, and therefore ΔYI could not be measured.

[0159] [Table 3]

[0160]

[0161] Industrial availability

[0162] The birefringence reducer of the present invention has a great birefringence reduction effect. Since the resin composition containing it does not impair the transparency of the resin itself, the birefringence is greatly reduced, the heat aging resistance is excellent, and there are no problems of flowability or mold contamination during molding. Therefore, it can be used as a high-performance molded article for various optical applications.

Claims

1. A thermoplastic resin composition comprising a birefringence reducer containing an organosiloxane compound having an aromatic group, in which the thermoplastic resin is compounded. The content of the birefringence reducer is more than 2 parts by weight and less than 15 parts by weight relative to 100 parts by weight of the thermoplastic resin. The organosiloxane compound having an aromatic group is a cyclic organosiloxane compound represented by the following general formula (1). In formula (1), R represents an aryl group with 6 to 14 carbon atoms that is arbitrarily chosen to have substituents, and n is an integer from 1 to 5. The thermoplastic resin is an aromatic polycarbonate resin.

2. The thermoplastic resin composition according to claim 1, wherein, In formula (1), R contains a phenyl or naphthyl group.

3. The thermoplastic resin composition according to claim 1 or 2, wherein, The aromatic polycarbonate resin is an aromatic polycarbonate resin with a glass transition temperature of 160°C or higher.

4. The thermoplastic resin composition according to claim 1 or 2, wherein, The aromatic polycarbonate resin is a resin in which all structural units except for the terminal groups contain more than 70 mol% of the structural units shown in formula (2) below. 。 5. The thermoplastic resin composition according to claim 1 or 2, wherein its birefringence is reduced.

6. A molded article formed from the thermoplastic resin composition according to any one of claims 1 to 5.

7. The molded body according to claim 6, wherein it is an optical molded body.

8. The shaped body according to claim 7 is an optical lens.

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