HK1237360B - Polycarbonate resin and optical lens - Google Patents

Description

Polycarbonate resin and optical lens

Technical Field

The present invention relates to a novel polycarbonate resin and an optical lens formed therefrom. Furthermore, the present invention relates to an optical lens having a well-balanced high Abbe number, low birefringence, high transparency, and high glass transition temperature (heat resistance).

Background Art

Optical glass or optically transparent resins can be used as materials for optical elements used in the optical systems of various cameras, including still cameras, film-integrated cameras, and video cameras. Optical glass offers excellent heat resistance, transparency, dimensional stability, and chemical resistance. While a variety of materials with varying refractive indices (nD) and Abbe numbers (νD) exist, they suffer from high material costs, poor molding processability, and low productivity. In particular, the processing of aspheric lenses used for aberration correction requires extremely advanced technology and high costs, presenting a significant obstacle to practical use.

On the other hand, optical lenses made of optical transparent resins, particularly thermoplastic transparent resins, can be mass-produced by injection molding and have the advantage of being easy to manufacture aspherical lenses. These lenses are currently used as camera lenses. Examples include polycarbonate containing bisphenol A, polystyrene, poly-4-methylpentene, polymethyl methacrylate, and amorphous polyolefins.

However, when using optically transparent resins for optical lenses, in addition to refractive index and Abbe number, they also require transparency, heat resistance, and low birefringence. Therefore, the balance of properties between the resins presents weaknesses, limiting their application areas. For example, polystyrene has low heat resistance and high birefringence, poly-4-methylpentene has low heat resistance, and polymethyl methacrylate has a low glass transition temperature, low heat resistance, and a low refractive index, limiting its application areas. Polycarbonate containing bisphenol A also has weaknesses such as high birefringence, limiting its application areas and making it undesirable.

On the other hand, generally, if the refractive index of an optical material is high, a lens element with the same refractive index can be realized using a surface with a smaller curvature, thereby reducing the amount of aberration occurring on that surface. The lens system can be made smaller and lighter by reducing the number of lenses, reducing the sensitivity of the lenses to decentering, and reducing the thickness of the lenses. Therefore, a high refractive index is useful.

Furthermore, in the optical design of optical units, it is known to correct chromatic aberration by combining multiple lenses with different Abbe numbers. For example, a lens made of an alicyclic polyolefin resin with an Abbe number of 45 to 60 is combined with a lens made of a polycarbonate resin containing bisphenol A (nD = 1.59, νD = 29) with a low Abbe number to correct chromatic aberration.

Among optical transparent resins used in practical applications for optical lenses, resins with high Abbe numbers include polymethyl methacrylate (PMMA) and cycloolefin polymers. Cycloolefin polymers are particularly widely used in optical lens applications due to their excellent heat resistance and mechanical properties.

Examples of resins having a low Abbe number include polyester and polycarbonate. For example, the resin described in Patent Document 1 is characterized by having a high refractive index and a low Abbe number.

There is a difference in the water expansion coefficient between cycloolefin polymers (high Abbe numbers) and polycarbonate resins (low Abbe numbers). If lenses made from these two materials are combined to form a lens unit, the lens size will differ when water is absorbed in the environment used in smartphones, etc. This difference in expansion coefficient can impair lens performance.

Patent Documents 2 to 4 describe polycarbonate copolymers containing a fully hydroxylated dimethylolnaphthalene skeleton. However, the dihydroxymethyl groups are located at the 2nd and 3rd positions, resulting in weak strength and unsuitable for optical lens applications. Furthermore, the polycarbonates described in Patent Documents 2 to 4 have low glass transition temperatures (Tg), resulting in problems with heat resistance. For example, the HOMO polycarbonate described in Example 1 of Patent Document 4 has a low glass transition temperature (Tg) of 125°C despite having a number average molecular weight of 38,000.

Prior art literature

Patent Literature

Patent Document 1: International Publication No. 2014/73496

Patent Document 2: Japanese Patent Application Laid-Open No. 5-70584

Patent Document 3: Japanese Patent Application Laid-Open No. 2-69520

Patent Document 4: Japanese Patent Application Laid-Open No. 5-341124

Summary of the Invention

Problems to be solved by the invention

The present invention aims to provide a high-Abbe-number resin having a small difference in water absorption expansion coefficient compared to a polycarbonate resin having a high refractive index and a low Abbe number, and to provide an optical lens made from the resin.

Methods for solving problems

The inventors of the present invention have conducted intensive studies to solve the above problems and have found that a polycarbonate resin using decahydro-1,4:5,8-dimethanol naphthalene diol (D-NDM) as a raw material can solve the above problems, thereby completing the present invention.

That is, the present invention relates to the polycarbonate resin and optical lens shown below.

<1> A polycarbonate resin comprising a structural unit represented by the following general formula (1).

(In general formula (1), R is H, CH ₃ or C ₂ H ₅ .)

<2> The polycarbonate resin according to <1>, comprising a mixture of an isomer in which the -CH ₂ O- group in the general formula (1) is bonded to the 6-position (2,6-position isomer) and an isomer in which the -CH ₂ O- group in the general formula (1) is bonded to the 7-position (2,7-position isomer).

<3> The polycarbonate resin according to <2> above, wherein the content ratio of the 2,6-position isomer to the 2,7-position isomer is 1.0:99.0 to 99.0:1.0 by mass ratio.

<4> The polycarbonate resin according to any one of <1> to <3> above, wherein the polycarbonate resin has a water absorption expansion coefficient of 0.01 to 0.5%.

<5> The polycarbonate resin according to any one of <1> to <4> above, wherein the polycarbonate resin has an Abbe number of 25 or greater.

<6> The polycarbonate resin according to any one of <1> to <5> above, wherein the polycarbonate resin has a glass transition temperature of 110 to 160°C.

<7> The polycarbonate resin according to any one of <1> to <6> above, wherein the polycarbonate resin has a weight average molecular weight of 5,000 to 50,000.

<8> An optical lens obtained by molding the polycarbonate resin according to any one of <1> to <7> above.

<9> A method for producing a polycarbonate resin, comprising reacting a diol compound represented by the following general formula (2) with a carbonic acid diester.

(In general formula (2), R is H, CH ₃ or C ₂ H ₅ .)

<10> The method for producing a polycarbonate resin according to <9> above, wherein the diol compound comprises a mixture of an isomer in which the -CH ₂ OH group in the general formula (2) is bonded to the 6-position (2,6-position isomer) and an isomer in which the -CH ₂ OH group in the general formula (2) is bonded to the 7-position (2,7-position isomer).

2,6-position isomers

2,7-position isomers.

<11> The method for producing a polycarbonate resin according to <10>, wherein the content ratio of the 2,6-isomer to the 2,7-isomer is 1.0:99.0 to 99.0:1.0 by mass ratio.

Effects of the Invention

The present invention provides a high-Abbe-number resin having a small difference in water absorption expansion coefficient relative to a polycarbonate resin having a high refractive index and a low Abbe number, and also provides an optical lens made from the resin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 shows the results of 1H-NMR measurement of the main reaction product obtained in Monomer Synthesis Example 1.

FIG. 2 shows the results of 13C-NMR measurement of the main reaction product obtained in Monomer Synthesis Example 1. FIG.

FIG. 3 shows the results of COSY-NMR measurement of the main reaction product obtained in Monomer Synthesis Example 1. FIG.

FIG. 4 shows the results of 1H-NMR measurement of the polycarbonate resin obtained in Example 3. FIG.

DETAILED DESCRIPTION

(A) Polycarbonate resin

The polycarbonate resin of the present invention comprises a structural unit represented by the general formula (1) (hereinafter referred to as "structural unit (1)"). An example of this is a structural unit derived from decahydro-1,4:5,8-dimethanol naphthalene diol (sometimes referred to as D-NDM). As described below, structural unit (1) is obtained by reacting a diol compound represented by the general formula (2) with a carbonic acid diester.

The polycarbonate resin of the present invention may contain other structural units in addition to the polycarbonate resin composed only of the structural unit (1).

Other constituent units that may be included are constituent units obtained by reacting a diol compound other than the general formula (2) with a carbonic acid diester. Examples of the diol compound other than the general formula (2) include bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, bisphenol Z, 9,9-bis(4-(2-hydroxyethyl)-1,2-diol)-1,2-diol 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, etc. Among them, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene is preferred.

The preferred polystyrene-equivalent weight average molecular weight (Mw) of the polycarbonate resin of the present invention is 5,000 to 300,000. The more preferred polystyrene-equivalent weight average molecular weight (Mw) is 30,000 to 120,000. In other preferred embodiments, the polystyrene-equivalent weight average molecular weight (Mw) is preferably 5,000 to 50,000, and more preferably 7,000 to 45,000. In addition, as preferred lower limits of the polystyrene-equivalent weight average molecular weight (Mw), 35,000 and 41,000 can be listed. If Mw is less than 5,000, the optical lens becomes brittle and is not preferred. If Mw is greater than 300,000, the melt viscosity becomes high, and it is difficult to extract the resin after manufacture, and the fluidity becomes poor, making it difficult to injection mold in a molten state, so it is not preferred.

The polycarbonate resin of the present invention has a reduced viscosity (ηsp/C) of 0.20 dl/g or more, preferably 0.23 to 0.84 dl/g.

Furthermore, it is preferable to add an antioxidant, a release agent, an ultraviolet absorber, a fluidity improver, a crystal nucleating agent, a reinforcing agent, a dye, an antistatic agent, an antibacterial agent, or the like to the polycarbonate resin of the present invention.

(B) Method for producing a diol compound represented by general formula (2)

The diol compound represented by the general formula (2) can be synthesized using dicyclopentadiene or cyclopentadiene and an olefin having a functional group as raw materials, for example, through the route represented by the following formula (3).

(In formula (3), R is H, CH ₃ or C ₂ H ₅ . _{R 1} is COOCH ₃ , COOC ₂ H ₅ , COOC ₃ H ₇ , COOC ₄ H ₉ or CHO.)

[Production of a monoolefin having 13 to 19 carbon atoms represented by formula (C)]

The monoolefin having 13 to 19 carbon atoms represented by formula (C) can be produced by a Diels-Alder reaction of an olefin having a functional group and dicyclopentadiene.

Examples of olefins having functional groups used in the above-mentioned Diels-Alder reaction include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methacrolein, and acrolein. More preferred olefins include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, methacrolein, and acrolein.

The dicyclopentadiene used in the Diels-Alder reaction is preferably a high-purity product, and it is desirable to avoid containing butadiene, isoprene, etc. as much as possible. The purity of dicyclopentadiene is preferably 90% or more, more preferably 95% or more. In addition, it is known that dicyclopentadiene depolymerizes into cyclopentadiene (so-called monocyclopentadiene) under heating conditions, so cyclopentadiene can be used instead of dicyclopentadiene. In addition, it is believed that the monoolefin with 13 to 19 carbon atoms represented by formula (C) can be considered to be substantially generated through the monoolefin with 8 to 14 carbon atoms represented by the following formula (4) (first stage Diels-Alder reaction product), and the monoolefin of formula (4) generated as a new dienophile reacts with cyclopentadiene (Diene) present in the reaction system based on the Diels-Alder reaction (second stage Diels-Alder reaction) to generate the monoolefin with 13 to 19 carbon atoms represented by formula (C).

(Wherein, R is H, CH ₃ or C ₂ H ₅ . _{R 1} is COOCH ₃ , COOC ₂ H ₅ , COOC ₃ H ₇ , COOC ₄ H ₉ or CHO.)

In order to efficiently carry out the Diels-Alder reaction in the second stage, it is important to have cyclopentadiene in the reaction system. Therefore, the reaction temperature is preferably 100°C or higher, more preferably 120°C or higher, and particularly preferably 130°C or higher. On the other hand, in order to suppress the by-production of high-boiling substances, the reaction is preferably carried out at a temperature of 250°C or lower. In addition, hydrocarbons, alcohols, esters, etc. can also be used as the reaction solvent, preferably aliphatic hydrocarbons with 6 or more carbon atoms, cyclohexane, toluene, xylene, ethylbenzene, mesitylene, propanol, butanol, etc.

As the reaction method of this Diels-Alder reaction, various reaction methods can be adopted, such as a batch method using a tank reactor, a semi-batch method in which a substrate or a substrate solution is supplied to a tank reactor under reaction conditions, and a continuous flow method in which a substrate is circulated in a tubular reactor under reaction conditions.

The reaction product obtained by the Diels-Alder reaction can be used directly as a raw material for the subsequent hydroformylation reaction, but can also be supplied to the next step after being purified by distillation, extraction, crystallization, or the like.

[Production of a bifunctional compound having 14 to 20 carbon atoms represented by formula (B)]

The difunctional compound having 14 to 20 carbon atoms represented by formula (B) in formula (3) can be produced by subjecting a monoolefin having 13 to 19 carbon atoms represented by formula (C), carbon monoxide and hydrogen to a hydroformylation reaction in the presence of a rhodium compound and an organophosphorus compound.

The rhodium compound used in the hydroformylation reaction can be in any precursor form, as long as it forms a coordination complex with an organophosphorus compound and exhibits hydroformylation activity in the presence of carbon monoxide and hydrogen. A catalyst precursor such as rhodium dicarbonyl acetylacetonate (hereinafter referred to as Rh(acac)(CO) ₂ ), _Rh2O3 , _Rh4 (CO) _{12 , Rh6} (CO) ₁₆ , or Rh( _NO3 ) ₃ can be introduced into the reaction mixture along with the organophosphorus compound to form a catalytically active rhodium metal hydride carbonylphosphorus complex within the reaction vessel. Alternatively, a rhodium metal hydride carbonylphosphorus complex can be prepared in advance and introduced into the reactor. A preferred specific example involves reacting Rh(acac)(CO) ₂ with an organophosphorus compound in the presence of a solvent, followed by introduction into the reactor along with excess organophosphorus compound to form a catalytically active rhodium-organophosphorus complex.

The inventors of the present invention were surprised to discover that a relatively large molecular weight second-stage Diels-Alder reaction product containing an internal olefin, such as that represented by formula (C), can be hydroformylated using a very small amount of rhodium catalyst. The amount of rhodium compound used in this hydroformylation reaction is preferably 0.1 to 30 micromoles, more preferably 0.2 to 20 micromoles, and even more preferably 0.5 to 10 micromoles per 1 mole of the monoolefin having 13 to 19 carbon atoms, represented by formula (C), which serves as the hydroformylation substrate. By limiting the amount of rhodium compound used to less than 30 micromoles per 1 mole of the monoolefin having 13 to 19 carbon atoms, the cost of the rhodium catalyst can be reduced, even without the need for rhodium complex recovery and recycling equipment, thereby alleviating the economic burden associated with such equipment.

In this hydroformylation reaction, examples of the organophosphorus compound that forms a rhodium compound and a catalyst for the hydroformylation reaction include phosphines represented by the general formula P( _-R1 )(- _R2 )(- _R3 ) or phosphites represented by P( _-OR1 )(- _OR2 )(- _OR3 ). Specific examples of _R1 , _R2 , and _R3 include aryl groups that may be substituted with an alkyl group or alkoxy group having 1 to 4 carbon atoms, and alicyclic alkyl groups that may be substituted with an alkyl group or alkoxy group having 1 to 4 carbon atoms. Triphenylphosphine and triphenylphosphite are preferred. The amount of the organophosphorus compound used is preferably 500 to 10,000 times the molar amount of the rhodium metal, more preferably 700 to 5,000 times the molar amount, and even more preferably 900 to 2,000 times the molar amount. When the amount of the organophosphorus compound used is less than 500 times the molar amount of the rhodium metal, the stability of the rhodium metal hydride carbonyl phosphorus complex as the catalyst active material is impaired, resulting in a slowdown in the reaction, which is not preferred. Furthermore, when the amount of the organophosphorus compound used is more than 10,000 times the molar amount of the rhodium metal, the cost of the organophosphorus compound increases, which is not preferred.

The hydroformylation reaction can also be carried out without using a solvent, but can be more suitably carried out by using a solvent that is inactive to the reaction. As a solvent, there is no particular limitation as long as it is a solvent that dissolves a monoolefin having 13 to 19 carbon atoms, dicyclopentadiene or cyclopentadiene, the above-mentioned rhodium compound, and the above-mentioned organophosphorus compound represented by formula (C). Specifically, solvents such as hydrocarbons such as aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons, esters such as aliphatic esters, alicyclic esters, and aromatic esters, alcohols such as aliphatic alcohols and alicyclic alcohols, and aromatic halides can be cited. Among these, hydrocarbons are preferably used, and alicyclic hydrocarbons and aromatic hydrocarbons are preferably used.

The temperature for conducting the hydroformylation reaction is preferably 40°C to 160°C, more preferably 80°C to 140°C. A reaction temperature of 40°C or higher achieves a sufficient reaction rate and suppresses the residual monoolefins used as the starting materials. Furthermore, by keeping the reaction temperature at 160°C or lower, the formation of by-products derived from the monoolefins used as the starting materials or the reaction products can be suppressed, thereby preventing a decrease in reaction performance.

When carrying out the hydroformylation reaction, it is necessary to carry out the reaction under pressure using carbon monoxide (hereinafter sometimes referred to as "CO") and hydrogen (hereinafter sometimes referred to as " _H2 ") gases. CO and _H2 gases can be introduced into the reaction system independently, or can be introduced into the reaction system as a pre-modulated mixed gas. The molar ratio of CO and _H2 gases introduced into the reaction system (=CO/ _H2 ) is preferably 0.2 to 5, more preferably 0.5 to 2, and more preferably 0.8 to 1.2. If the molar ratio of CO and _H2 gases deviates from this range, the reaction activity of the hydroformylation reaction and the selectivity of the target aldehyde may be reduced. The CO and _H2 gases introduced into the reaction system gradually decrease as the reaction proceeds, so if a pre-modulated mixed gas of CO and _H2 is used, the reaction control may be simplified.

The reaction pressure of the hydroformylation reaction is preferably 1 to 12 MPa, more preferably 1.2 to 9 MPa, and even more preferably 1.5 to 5 MPa. Setting the reaction pressure above 1 MPa allows for a sufficient reaction rate and suppresses residual monoolefins, the raw materials. Furthermore, setting the reaction pressure below 12 MPa eliminates the need for expensive, pressure-resistant equipment, resulting in economic advantages. In particular, when conducting the reaction in a batch or semi-batch manner, CO and _H₂ gases must be vented and the pressure reduced after completion of the reaction. Lowering the pressure minimizes CO and _H₂ gas losses, resulting in economic advantages.

The hydroformylation reaction is preferably carried out in a batch or semi-batch manner. The semi-batch reaction can be carried out by adding a rhodium compound, an organophosphorus compound, and the above-mentioned solvent to a reactor, subjecting the reactor to the aforementioned reaction conditions by pressurizing and heating the reactor using CO/ _H₂ gas, and then supplying a monoolefin as a raw material or a solution thereof to the reactor.

The reaction product obtained by the above-mentioned hydroformylation reaction can be used directly as a raw material for the subsequent reduction reaction, but can also be supplied to the next step after being purified by distillation, extraction, crystallization, etc.

[Production of a bifunctional compound having 14 to 16 carbon atoms represented by formula (A)]

The bifunctional compound having 14 to 16 carbon atoms represented by formula (A) in formula (3) can be produced by reducing the bifunctional compound having 14 to 20 carbon atoms represented by formula (B) in the presence of a hydrogenating catalyst and hydrogen.

In the reduction reaction, a catalyst containing at least one element selected from copper, chromium, iron, zinc, aluminum, nickel, cobalt, and palladium can be used as a catalyst having hydrogenation ability. Examples of such catalysts include Cu-Cr catalysts, Cu-Zn catalysts, Cu-Zn-Al catalysts, Raney-Ni catalysts, Raney-Co catalysts, and the like.

The usage amount of the above-mentioned hydrogenation catalyst is 1 to 100 weight %, preferably 2 to 50 weight %, more preferably 5 to 30 weight % relative to the difunctional compound of carbon number 14 to 20 shown in the formula (B) as substrate. By setting the catalyst usage amount in these ranges, hydrogenation reaction can be suitably implemented. When the catalyst usage amount is small, the reaction is not completed, and as a result, the yield of the target product decreases. In addition, when the catalyst usage amount is large, the improvement effect of the speed of response commensurate with the catalyst amount supplied to the reaction is not obtained.

The reaction temperature of the reduction reaction is preferably 80 to 250°C, more preferably 100 to 230°C. By setting the reaction temperature to 250°C or below, side reactions and decomposition reactions can be suppressed, and the target product can be obtained in high yield. In addition, by setting the reaction temperature to 80°C or above, the reaction can be completed in a moderate time, which can avoid a decrease in productivity and a decrease in the yield of the target product.

The reaction pressure of the reduction reaction is preferably 1 to 20 MPa as a hydrogen partial pressure, more preferably 2 to 15 MPa. By setting the hydrogen partial pressure below 20 MPa, it is possible to suppress the occurrence of side reactions and decomposition reactions and obtain the target product in a high yield. In addition, by setting the hydrogen partial pressure to above 1 MPa, it is possible to complete the reaction in a suitable time, thereby avoiding a decrease in productivity and a decrease in the yield of the target product. In addition, it is also possible to allow a gas inactive to the reduction reaction (e.g., nitrogen or argon) to coexist.

A solvent can be used in the reduction reaction. As the solvent, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, alcohols, etc. can be used, among which alicyclic hydrocarbons, aromatic hydrocarbons, and alcohols are preferred. Specifically, cyclohexane, toluene, xylene, methanol, ethanol, 1-propanol, etc. can be mentioned.

As the reaction mode of the reduction reaction, various reaction modes can be adopted, such as a batch method using a tank reactor, a semi-batch method in which a substrate or a substrate solution is supplied to a tank reactor under reaction conditions, and a continuous flow method in which a substrate or a substrate solution is circulated in a tubular reactor filled with a molded catalyst under reaction conditions.

The reaction product obtained by the reduction reaction can be purified by, for example, distillation, extraction, crystallization, or the like.

(C) Method for producing polycarbonate resin

The polycarbonate resin of the present invention can be produced by a melt polycondensation method using a diol compound represented by general formula (2) and a carbonic acid diester as raw materials. The diol compound represented by general formula (2) contains a mixture of isomers with hydroxymethyl groups at the 2,6 positions and isomers at the 2,7 positions. The mass ratio of these isomers is 0.1:99.9 to 99.9:0.1 for the 2,6 position isomer:99.9 to 99.9:0.1. From the perspective of resin properties such as resin strength, tensile elongation, and the appearance of molded articles, the ratio of 2,6 position isomer:99.0 to 99.0:1 is preferred, 2,6 position isomer:99.0 to 1.0 is more preferred, and 2,6 position isomer:99.0 to 20 is more preferred, with 50:50 to 80:20 being particularly preferred. Furthermore, it can be used in combination with other diol compounds. This reaction can be carried out in the presence of a basic compound catalyst, an ester exchange catalyst, or a mixed catalyst containing both as a polycondensation catalyst.

Examples of carbonic acid diesters include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonic acid diester, m-cresyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and dicyclohexyl carbonate. Among these, diphenyl carbonate is particularly preferred from the perspectives of reactivity and purity. Carbonic acid diesters are preferably used at a ratio of 0.97 to 1.20 moles, more preferably 0.98 to 1.10 moles, per 1 mole of the diol component. Adjusting this molar ratio allows the molecular weight of the polycarbonate resin to be controlled.

Examples of the basic compound catalyst include alkali metal compounds, alkaline earth metal compounds, and nitrogen-containing compounds.

Examples of the alkali metal compound used in the present invention include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, and alkoxides of alkali metals. Specifically, sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium phenylborate, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenylphosphate, disodium salt, dipotassium salt, dicesium salt, dilithium salt of bisphenol A, sodium salt, potassium salt, cesium salt, and lithium salt of phenol. Sodium carbonate and sodium bicarbonate are preferred from the viewpoints of catalyst effect, price, circulation, and influence on the hue of the resin.

Examples of the alkaline earth metal compound include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, and alkoxides of alkaline earth metal compounds. Specifically, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium hydrogen carbonate, calcium hydrogen carbonate, strontium hydrogen carbonate, barium hydrogen carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium acetate, calcium acetate, strontium acetate, barium acetate, magnesium stearate, calcium stearate, calcium benzoate, and magnesium phenylphosphate can be used.

Examples of nitrogen-containing compounds include quaternary ammonium hydroxides and their salts, and amines. Specifically, quaternary ammonium hydroxides having an alkyl group, an aryl group, or the like, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide; tertiary amines such as triethylamine, dimethylbenzylamine, and triphenylamine; secondary amines such as diethylamine and dibutylamine; primary amines such as propylamine and butylamine; imidazoles such as 2-methylimidazole, 2-phenylimidazole, and benzimidazole; or bases or basic salts thereof such as ammonia, tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate, and tetraphenylammonium tetraphenylborate.

As the transesterification catalyst, salts of zinc, tin, zirconium, and lead are preferably used, and these can be used alone or in combination. In addition, they can also be used in combination with the above-mentioned alkali metal compounds and/or alkaline earth metal compounds.

Specific examples of the transesterification catalyst that can be used include zinc acetate, zinc benzoate, zinc 2-ethylhexanoate, tin (II) chloride, tin (IV) chloride, tin (II) acetate, tin (IV) acetate, dibutyltin dilaurate, dibutyltin oxide, dibutyltin dimethoxy, zirconium acetylacetonate, zirconium oxyacetate, zirconium tetrabutoxide, lead (II) acetate, and lead (IV) acetate.

These catalysts are used at a ratio of 1×10 ⁻⁹ to 1×10 ⁻³ mol, preferably 1×10 ⁻⁷ to 1×10 ⁻⁴ mol, per 1 mol of the total diol compound.

The melt polycondensation method uses the above-mentioned raw materials and catalysts, and carries out a transesterification reaction under heating at normal pressure or reduced pressure while removing by-products. The reaction is usually carried out in two or more stages.

Specifically, the first stage reaction is carried out at a temperature of 120-260°C, preferably 180-240°C, for 0.1-5 hours, preferably 0.5-3 hours. Subsequently, the diol compound and the carbonate diester are reacted while increasing the degree of decompression in the reaction system and the reaction temperature. Finally, a polycondensation reaction is carried out at a temperature of 200-350°C under a reduced pressure of less than 1 mmHg for 0.05-2 hours. This reaction can be carried out either continuously or batchwise. The reaction apparatus used for the above reaction can be a vertical type equipped with an anchor-type impeller, a large wide-blade (Maxblend) impeller, a ribbon-type impeller, or a horizontal type equipped with a paddle blade, a grid blade, a spectacled impeller, or a screw extruder. Furthermore, a suitable combination of these reaction apparatuses is preferably used, taking into account the viscosity of the polymer.

In the method for producing the polycarbonate resin of the present invention, after the polymerization reaction is completed, the catalyst may be removed or deactivated in order to maintain thermal stability and hydrolytic stability. It is generally preferred to implement a method in which a known acidic substance is added to deactivate the catalyst. As these substances, specifically, esters such as butyl benzoate, aromatic sulfonic acids such as p-toluenesulfonic acid, aromatic sulfonic acid esters such as butyl p-toluenesulfonate and hexyl p-toluenesulfonate, phosphoric acids such as phosphoric acid, phosphoric acid, phosphonic acid, triphenyl phosphite, monophenyl phosphite, diphenyl phosphite, diethyl phosphite, di-n-propyl phosphite, di-n-butyl phosphite, di-n-hexyl phosphite, dioctyl phosphite, monooctyl phosphite, triphenyl phosphate, phosphoric acid, diphenyl phosphate, phosphonic acid ... Phosphates such as monophenyl ester, dibutyl phosphate, dioctyl phosphate, and monooctyl phosphate; phosphonic acids such as diphenylphosphonic acid, dioctylphosphonic acid, and dibutylphosphonic acid; phosphonates such as diethyl phenylphosphonate; phosphines such as triphenylphosphine and bis(diphenylphosphino)ethane; boric acids such as boric acid and phenylboric acid; aromatic sulfonates such as tetrabutylphosphonium dodecylbenzenesulfonate; organic halides such as stearoyl chloride, benzoyl chloride, and p-toluenesulfonyl chloride; alkylsulfuric acids such as dimethylsulfuric acid; and organic halides such as benzyl chloride. From the perspectives of deactivation effect, resin color, and stability, butyl p-toluenesulfonate is preferably used. These deactivators are used in an amount of 0.01 to 50 times the molar amount, preferably 0.3 to 20 times the molar amount, relative to the amount of the catalyst. If the amount is less than 0.01 times the molar amount, the deactivation effect becomes insufficient, which is not preferred. On the other hand, if the molar amount is more than 50 times the amount of the catalyst, heat resistance is lowered and the molded article is easily colored, which is not preferred.

After the catalyst is deactivated, a step may be performed to remove low-boiling-point compounds in the polymer at a pressure of 0.1 to 1 mmHg and a temperature of 200 to 350°C. For this purpose, a horizontal device equipped with a stirring blade having excellent surface renewal ability, such as a paddle blade, a lattice blade, or a spectacle blade, or a thin-film evaporator may be used.

The polycarbonate resin of the present invention desirably contains as little foreign matter as possible. Therefore, filtration of the molten raw material and the catalyst solution is preferably performed. The pore size of the filter is preferably 5 μm or less, more preferably 1 μm or less. Furthermore, the produced resin is preferably filtered through a polymer filter. The pore size of the polymer filter is preferably 100 μm or less, more preferably 30 μm or less. Furthermore, the resin pellet collection process must be performed in a low-dust environment, preferably at a dust level of 1000 or less, more preferably at a dust level of 100 or less.

(D) Physical properties of polycarbonate resin

The optical lens of the present invention has a high Abbe number, high transparency, moderate water absorption rate, and moderate water absorption expansion rate.

The polycarbonate resin of the present invention preferably has a glass transition temperature (Tg) of 95 to 180°C, more preferably 110 to 160°C, and particularly preferably 120 to 160°C. Preferred lower limits of the glass transition temperature (Tg) include 130°C and 140°C, and a preferred upper limit of 150°C. A Tg below 95°C is not preferred because the operating temperature range of lenses and cameras is narrowed. A Tg exceeding 180°C is also not preferred because the molding conditions during injection molding become stricter.

The polycarbonate resin of the present invention preferably has a refractive index of 1.50 to 1.65, more preferably 1.52 to 1.55, as measured by the method of JIS-K-7142 after molding.

The polycarbonate resin of the present invention has an Abbe number of 25 or more, preferably 40 or more, and more preferably 50 or more, as measured by the method of JIS-K-7142 after molding. The upper limit of the Abbe number is about 60.

The polycarbonate resin of the present invention has a total light transmittance of 85.0% or more, preferably 87.0% or more, as measured by integrating sphere photoelectric photometry after molding. The upper limit of the total light transmittance is approximately 99%.

The polycarbonate resin of the present invention preferably has a water absorption rate of 0.2 to 0.5%, more preferably 0.3 to 0.4%, as measured by the method of JIS-K-7209.

The water absorption expansion coefficient of the polycarbonate resin of the present invention is preferably 0.01 to 0.5%, more preferably 0.03 to 0.4%.

The water absorption expansion ratio was measured using a micrometer (accuracy: 1/1000 mm). The diameter of the circular plate used for the water absorption measurement was measured, and the change (%) in diameter before and after water absorption was taken as the water absorption expansion ratio.

(E) Optical lens

The optical lens of the present invention can be obtained by injection molding the polycarbonate resin of the present invention into a lens shape using an injection molding machine or an injection compression molding machine. The injection molding conditions are not particularly limited, but the molding temperature is preferably 180 to 280°C. Furthermore, the injection pressure is preferably 50 to 1700 kg/ ^cm2 .

In order to minimize the incorporation of foreign matter into the optical lens, the molding environment must of course be a low-dust environment, preferably below level 1000, more preferably below level 100.

The optical lens of the present invention is preferably used in the form of an aspheric lens, as needed. Aspheric lenses can essentially eliminate spherical aberration in a single lens, eliminating the need to remove spherical aberration by combining multiple spherical lenses. This can achieve lightweighting and reduced production costs. Therefore, aspheric lenses are particularly useful as camera lenses among optical lenses. The astigmatism of an aspheric lens is preferably 0 to 15 mλ, more preferably 0 to 10 mλ.

The thickness of the optical lens of the present invention can be set within a wide range depending on the intended use and is not particularly limited. However, it is preferably 0.01 to 30 mm, and more preferably 0.1 to 15 mm. The surface of the optical lens of the present invention may be provided with a coating such as an antireflection layer or a hard coat layer as needed. The antireflection layer may be a single layer or multiple layers, and may be organic or inorganic, but is preferably inorganic. Specifically, examples include oxides or fluorides such as silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, magnesium oxide, and magnesium fluoride. Of these, silicon oxide and zirconium oxide are more preferred, and a combination of silicon oxide and zirconium oxide is even more preferred. Regarding the antireflection layer, there are no particular limitations on the combination of single layer/multilayer, or the combination of these components and thicknesses, but a two-layer or three-layer structure is preferred, with a three-layer structure being particularly preferred. Furthermore, the antireflection layer as a whole may be formed to a thickness of 0.00017 to 3.3% of the thickness of the optical lens, specifically 0.05 to 3 μm, and particularly preferably 1 to 2 μm.

Example

The present invention is described below by way of examples, but the present invention is not limited by these examples. In addition, the measured values in the examples were measured using the following methods or apparatuses. 1) Polystyrene-equivalent weight average molecular weight (Mw):

GPC was used with tetrahydrofuran as the developing solvent and a calibration curve was prepared using standard polystyrenes of known molecular weight (molecular weight distribution = 1). Based on this calibration curve, the retention time of GPC was calculated.

2) Glass transition temperature (Tg):

Measured by differential scanning calorimetry (DSC).

3) Refractive index nD, Abbe number νD:

A polycarbonate resin was press-molded (molding conditions: 200° C., 100 kgf/cm ² , 2 minutes) into a 3 mm thick circular plate, which was cut out at a right angle and measured using KPR-200 manufactured by Kalnew.

4) Total light transmittance:

The total light transmittance was measured using MODEL 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. The total light transmittance was measured for a circular plate (thickness 3 mm) obtained by press molding.

5) Saturated water absorption

The circular plate (thickness 3 mm) obtained by press molding was measured in accordance with JIS-K-7209.

6) Water absorption expansion rate

The diameter of the sample used for the water absorption measurement was measured with a micrometer (manufactured by Mitutoyo, accuracy of 1/1000 mm) before and after water absorption, and the diameter change rate (%) was calculated according to the following mathematical formula (1).

Water absorption expansion ratio at saturation = {(disc diameter at saturation) - (disc diameter before water absorption measurement)} × 100 / (disc diameter before water absorption measurement)

Mathematical formula (1)

<Monomer Synthesis Example 1>

In a 500 ml stainless steel reactor, 173 g (2.01 mol) of methyl acrylate and 167 g (1.26 mol) of dicyclopentadiene were added and reacted at 195°C for 2 hours. A reaction liquid containing 96 g of the monoolefin represented by the following formula (3a) was obtained and purified by distillation, and a portion thereof was supplied to the subsequent reaction.

A 300 ml stainless steel reactor was used to carry out a hydroformylation reaction of a monoolefin represented by formula (3a) using a CO/ _H₂ mixed gas (CO/ _H₂ molar ratio = 1) and distillation purification. 70 g of the monoolefin represented by formula (3a), 140 g of toluene, 0.50 g of triphenyl phosphite, and 550 μl of a separately prepared toluene solution of Rh(acac)(CO) _₂ (concentration 0.003 mol/L) were added to the reactor. After replacement with nitrogen and a CO/ _H₂ mixed gas three times, the system was pressurized with a CO/ _H₂ mixed gas and the reaction was carried out at 100°C and 2 MPa for 5 hours. After completion of the reaction, gas chromatography analysis of the reaction liquid confirmed that the reaction liquid contained 76 g of the difunctional compound represented by formula (2a) and 1.4 g of the monoolefin represented by formula (3a) (conversion 98%, selectivity 97%). The reaction liquid was then distilled and purified, and a portion was supplied to the subsequent reaction.

50 g of the difunctional compound represented by formula (2a) purified by distillation, 10 g of a Cu-Zn-Al catalyst (E-01X, manufactured by Nikko Catalysts & Chemicals Co., Ltd.), and 150 g of toluene were added to a 300 ml stainless steel reactor. The system was pressurized with hydrogen and the reaction was carried out at 10 MPa and 215°C for 8 hours. After the reaction, the resulting slurry was diluted with methanol, the catalyst was filtered through a membrane filter with a pore size of 0.2 μm, and the solvent was distilled off using an evaporator. Analysis by gas chromatography and GC-MS confirmed the presence of 43 g of a main product with a molecular weight of 222 (main product yield 96%). This was further purified by distillation to obtain the main product.

(Wherein, Me represents a methyl group.)

＜Product Identification＞

NMR analysis, gas chromatography analysis, and GC-MS analysis were performed on the components obtained in Monomer Synthesis Example 1. The NMR spectra are shown in Figures 1 to 3 .

1) NMR measurement conditions

Device: JEOL Ltd., JNM-ECA500 (500MHz)

Measurement modes: 1H-NMR, 13C-NMR, COSY-NMR

Solvent: CD ₃ OD (deuterated methanol)

Internal standard substance: tetramethylsilane

2) Gas chromatography conditions

Analytical equipment: Capillary gas chromatograph GC-2010Plus manufactured by Shimadzu Corporation

·Analytical column: Made by GL Sciences Co., Ltd., InertCap1 (30m, 0.32mmI.D., film thickness 0.25μm)

Column oven temperature: 60°C (hold for 0.5 minutes) - temperature rise at 15°C/minute - 280°C (hold for 4 minutes) Detector: FID, temperature 280°C

3) GC-MS measurement conditions

·Analysis device: manufactured by Shimadzu Corporation, GCMS-QP2010Plus

Ionization voltage: 70eV

Analytical column: Agilent Technologies, DB-1 (30 m, 0.32 mm ID, film thickness 1.00 μm)

Column oven temperature: 60°C (hold for 0.5 minutes) - temperature rise at 15°C/minute - 280°C (hold for 4 minutes) Detector temperature: 280°C

GC-MS analysis and NMR analysis results shown in Figures 1 to 3 confirmed that the main product obtained in Monomer Synthesis Example 1 was the diol compound (D-NDM) represented by formula (1a) above. Furthermore, analysis by gas chromatography confirmed that the obtained diol compound was an isomer mixture containing 76% by mass of the isomer with hydroxymethyl groups at the 2,6 positions and 24% by mass of the isomer with hydroxymethyl groups at the 2,7 positions.

<Monomer Synthesis Example 2>

· A reaction liquid containing 86 g of a monoolefin represented by the following formula (3b) was obtained by using 141 g of methacrolein (1.93 mol/purity 96%) instead of methyl acrylate in Monomer Synthesis Example 1. This was purified by distillation and a portion thereof was supplied to the subsequent reaction.

· Using a 300 ml stainless steel reactor, a hydroformylation reaction of a monoolefin represented by formula (3b) was carried out using a CO/H ₂ mixed gas (CO/H ₂ molar ratio = 1). 70 g of the monoolefin represented by formula (3b), 140 g of toluene, 0.55 g of triphenyl phosphite, and 580 μl of a separately prepared toluene solution of Rh(acac)(CO) ₂ (concentration 0.003 mol/L) were added to the reactor. After substitution with nitrogen and CO/H ₂ mixed gas three times, the system was pressurized with a CO/H ₂ mixed gas and the reaction was carried out at 100°C and 2 MPa for 6 hours. After the reaction was completed, the reaction liquid was analyzed by gas chromatography. It was confirmed that the reaction liquid contained 77 g of a difunctional compound represented by the following formula (2b) and 1.3 g of a monoolefin represented by formula (3b) (conversion rate 98%, selectivity 98%)

50 g of the difunctional compound represented by formula (2b) purified by distillation, 150 g of toluene, and 10 ml of Raney cobalt catalyst were added to a 300 ml stainless steel reactor. The system was pressurized with hydrogen and the reaction was carried out at 4 MPa and 100°C for 5 hours. After the reaction, the resulting slurry was diluted with methanol, and the catalyst was filtered through a membrane filter with a pore size of 0.2 μm. The solvent was distilled off using an evaporator, and analysis by gas chromatography and GC-MS confirmed the presence of 49 g of a main product with a molecular weight of 236 (yield 96%).

The obtained main product was confirmed to be a bifunctional compound represented by the following formula (1b).

<Monomer Synthesis Example 3>

In the same manner as in Monomer Synthesis Example 1, the monoolefin represented by formula (3a) was synthesized and purified by distillation.

A 300 ml stainless steel reactor was used to carry out a hydroformylation reaction of the monoolefin represented by formula (3a) using a CO/ _H2 mixed gas (CO/ _H2 molar ratio = 1). A stainless steel tank was charged with 70 g of the monoolefin represented by formula (3a) and 100 g of toluene. After replacing the atmosphere with nitrogen and the CO/ _H2 mixed gas three times, the system was slightly pressurized with the CO/ _H2 mixed gas. Separately, a 300 ml stainless steel reactor was charged with 40 g of toluene, 0.13 g of triphenyl phosphite, and 120 μl of a separately prepared toluene solution of Rh(acac)(CO) ₂ (concentration 0.003 mol/L). After replacing the atmosphere with nitrogen and the CO/ _H2 mixed gas three times, the system was pressurized with the CO/ _H2 mixed gas and maintained at 100°C and 2 MPa. The toluene solution of the monoolefin represented by formula (3a) was supplied to the reactor from the above-mentioned stainless steel tank over 2 hours (during which the reactor was controlled at 100°C and 2 MPa). After the supply was completed, the reactor was aged at 100°C and 2 MPa for 3 hours. After the reaction was completed, the reaction liquid was analyzed by gas chromatography. It was confirmed that the reaction liquid contained 78 g of the difunctional compound represented by formula (2a) and 0.73 g of the monoolefin represented by formula (3a) (conversion rate 99%, selectivity 99%).

In the same manner as in Monomer Synthesis Example 1, a reduction reaction (reaction yield 96%) was carried out using the diol compound represented by formula (2a) as a raw material, followed by purification by distillation to obtain the diol compound represented by formula (1a) (D-NDM). Analysis by gas chromatography confirmed that the obtained diol compound was an isomer mixture containing 52% by mass of the isomer with hydroxymethyl groups at the 2 and 6 positions and 48% by mass of the isomer with hydroxymethyl groups at the 2 and 7 positions.

<Monomer Synthesis Example 4>

A reaction solution containing 14 g of the monoolefin represented by the following formula (3c) was obtained by using 52 g of ethacrylic acid (0.61 mol/99% purity) of ethyl acrolein instead of methyl acrylate in Monomer Synthesis Example 1. This reaction was carried out twice, and after purification by distillation, a portion was supplied to the subsequent reaction.

A 300 ml stainless steel reactor was used to carry out a hydroformylation reaction of a monoolefin represented by formula (3c) using a CO/H ₂ mixed gas (CO/H ₂ molar ratio = 1). 21.3 g of the monoolefin represented by formula (3c), 20 g of toluene, 518 mg of triphenylphosphine, and 128 μl of a separately prepared toluene solution of Rh(acac)(CO) ₂ (concentration 0.0384 mol/L) were added to the reactor. After three substitutions with nitrogen and a CO/H ₂ mixed gas, the system was pressurized with a CO/H ₂ mixed gas and the reaction was carried out at 110°C and 2 MPa for 1.5 hours. After completion of the reaction, the reaction liquid was analyzed by gas chromatography under the above-mentioned conditions. As a result, it was confirmed that the reaction liquid contained 23.8 g of a difunctional compound represented by the following formula (2c) (yield 98%).

A reaction solution containing 22.7 g of a difunctional compound represented by formula (2c), 38 g of cyclohexanol, and 2.2 g of a Cu-Zn-Al catalyst (manufactured by Nikko Catalysts & Chemicals Co., Ltd.: E-01X) were added to a 300 ml stainless steel reactor. The system was pressurized with hydrogen and the reaction was carried out at 3 MPa and 140°C for 1.5 hours. After the reaction, the obtained slurry was diluted with methanol, and the catalyst was filtered with a membrane filter with a pore size of 0.2 μm. The solvent was distilled off using an evaporator, and the analysis was performed using gas chromatography and GC-MS under the above conditions. GC-MS analysis confirmed that the main product obtained was a difunctional compound represented by formula (1c). In addition, it was confirmed that the amount of the difunctional compound represented by formula (1c) produced was 22 g (yield 96%).

<Example 1>

23.53 g (0.106 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 23.02 g (0.107 mol) of diphenyl carbonate, and 0.07 mg (0.8 μmol) of sodium bicarbonate were placed in a 300 mL reactor equipped with a stirrer and a distillation device. The mixture was heated to 215°C over 1 hour with stirring under a nitrogen atmosphere of 760 Torr. The transesterification reaction was initiated at 200°C using an oil bath. Stirring began 5 minutes after the reaction began, and 20 minutes later, the pressure was reduced from 760 Torr to 200 Torr over 10 minutes. The temperature was heated to 210°C while maintaining the pressure. 70 minutes after the reaction began, the temperature was raised to 220°C. 80 minutes later, the pressure was reduced to 150 Torr over 30 minutes. The temperature was then raised to 240°C, the pressure was reduced to 1 Torr, and then maintained for 10 minutes to obtain a polycarbonate resin.

The resulting polycarbonate resin had an Mw of 8,000 and a Tg of 110°C. It also had a refractive index of 1.536 and an Abbe number of 55.2. Its total light transmittance was 90%. Furthermore, its saturated water absorption was 0.38%, and its saturated water expansion coefficient was 0.038%. The results are shown in Tables 1 and 2.

<Example 2>

23.20 g (0.104 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 22.62 g (0.106 mol) of diphenyl carbonate, and 0.26 mg (3.1 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The same procedures as in Example 1 were followed, except for the loading amounts, to obtain a polycarbonate resin. The resulting polycarbonate resin had an Mw of 15,000 and a Tg of 127°C. It also had a refractive index of 1.534 and an Abbe number of 56.0. Its total light transmittance was 90%. Its saturated water absorption was 0.34%, and its saturated water absorption expansion was 0.036%.

<Example 3>

30.9 g (0.139 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 29.8 g (0.139 mol) of diphenyl carbonate, and 0.09 mg (1.1 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The same procedure as in Example 1 was followed, except for the loading amounts, to obtain a polycarbonate resin. The resulting polycarbonate resin had an Mw of 42,000 and a Tg of 141°C. It also had a refractive index of 1.531 and an Abbe number of 57.3. Its total light transmittance was 90%. Its saturated water absorption was 0.35%, and its saturated water absorption expansion was 0.033%.

The obtained polycarbonate resin was subjected to NMR analysis under the following measurement conditions. The NMR spectrum is shown in FIG4 .

NMR measurement conditions

Device: JEOL Ltd., JNM-ECA500 (500MHz)

·Measurement mode: 1H-NMR

Solvent: deuterated chloroform

Internal standard substance: tetramethylsilane

<Example 4>

28.9 g (0.130 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 6.3 g (0.014 mol) of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 31.5 g (0.147 mol) of diphenyl carbonate, and 0.09 mg (1.1 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The reaction was repeated in the same manner as in Example 1, except for the amount of material charged, to obtain a polycarbonate resin. The obtained polycarbonate resin had an Mw of 27,000 and a Tg of 142°C. It had a refractive index of 1.551 and an Abbe number of 45.5. Its total light transmittance was 90%. Its saturated water absorption was 0.37%, and its water absorption expansion coefficient at saturation was 0.038%.

<Example 5>

4.76 g (0.021 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 37.6 g (0.086 mol) of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 23.3 g (0.109 mol) of diphenyl carbonate, and 0.07 mg (0.9 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The reaction was repeated in the same manner as in Example 1, except for the amount of material charged, to obtain a polycarbonate resin. The obtained polycarbonate resin had an Mw of 32,000 and a Tg of 146°C. It had a refractive index of 1.626 and an Abbe number of 25.3. Its total light transmittance was 89%. Its saturated water absorption was 0.37%, and its water absorption expansion coefficient at saturation was 0.033%.

<Example 6>

11.3 g (0.051 mol) of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1, 20.0 g (0.046 mol) of 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 21.0 g (0.098 mol) of diphenyl carbonate, and 0.05 mg (0.6 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The reaction was repeated in the same manner as in Example 1, except for the amount of material charged, to obtain a polycarbonate resin. The obtained polycarbonate resin had an Mw of 35,000 and a Tg of 144°C. It also had a refractive index of 1.597 and an Abbe number of 30.0. Its total light transmittance was 89%. Its saturated water absorption was 0.37%, and its water absorption expansion coefficient at saturation was 0.038%.

<Example 7>

A polycarbonate resin was synthesized under the same conditions as in Example 1, except that the D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 3 was used. The resulting polycarbonate resin had an Mw of 38,000, a Tg of 140°C, a refractive index of 1.532, and an Abbe number of 57.2. Its total light transmittance was 90%. Furthermore, its saturated water absorption was 0.34%, and its saturated water expansion coefficient was 0.033%.

<Example 8>

The isomer mixture of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 3 (hydroxymethyl group isomers at the 2,6 positions = 52 mass % and 2,7 positions = 48 mass %) was distilled to obtain D-NDM containing 22 mass % of the 2,6 position isomers and 78 mass % of the 2,7 position isomers. A polycarbonate resin was synthesized under the same conditions as in Example 1, except that this D-NDM was used. The resulting polycarbonate resin had an Mw of 41,000, a Tg of 137°C, a refractive index of 1.531, and an Abbe number of 57.0. Its total light transmittance was 90%. Its saturated water absorption was 0.35%, and its saturated water absorption expansion coefficient was 0.033%.

＜Example 9＞

The isomer mixture of D-NDM represented by formula (1a) obtained in Monomer Synthesis Example 1 (hydroxymethyl group isomers at the 2,6 positions = 76 mass % and 2,7 positions = 24 mass %) was distilled to obtain D-NDM containing 99.5 mass % of the 2,6 positions isomers and 0.5 mass % of the 2,7 positions isomers. A polycarbonate resin was synthesized under the same conditions as in Example 1, except that this D-NDM was used.

A disc-shaped molded article molded from the resulting polycarbonate resin for refractive index and Abbe number measurement was found to be turbid due to crystallization, failing to meet the requirements for evaluation of the refractive index and Abbe number for use as an optical material. The resulting polycarbonate resin had an Mw of 40,000 and a Tg of 143°C. Its saturated water absorption was 0.33%, and its saturated water expansion coefficient was 0.031%.

<Example 10>

25.05 g (0.106 mol) of D-NDM represented by the following formula (1b), obtained in Monomer Synthesis Example 2, 22.78 g (0.106 mol) of diphenyl carbonate, and 0.26 mg (3.1 μmol) of sodium bicarbonate were placed in a 300 mL reactor equipped with a stirrer and a distillation device. The mixture was heated and stirred at 215°C for 1 hour under a nitrogen atmosphere of 760 Torr. The transesterification reaction was initiated at 200°C by heating in an oil bath. Stirring was initiated 5 minutes after the reaction commenced, and 20 minutes later, the pressure was reduced from 760 Torr to 200 Torr over 10 minutes. The temperature was heated to 210°C while the pressure was reduced. 70 minutes after the reaction commenced, the temperature was raised to 220°C, and 80 minutes later, the pressure was reduced to 150 Torr over 30 minutes. The temperature was then raised to 240°C, the pressure was reduced to 1 Torr, and then maintained for 10 minutes to obtain a polycarbonate resin.

The resulting polycarbonate resin had an Mw of 38,000 and a Tg of 135°C. It also had a refractive index of 1.533 and an Abbe number of 56.8. Its total light transmittance was 90%. Its saturated water absorption was 0.33%, and its saturated water expansion coefficient was 0.035%.

<Example 11>

26.54 g (0.104 mol) of D-NDM represented by the following formula (1c), obtained in Monomer Synthesis Example 4, 22.78 g (0.106 mol) of diphenyl carbonate, and 0.26 mg (3.1 μmol) of sodium bicarbonate were added to a 300 mL reactor equipped with a stirrer and a distillation device. The same procedure as in Example 1 was followed, except for the loading amounts, to obtain a polycarbonate resin. The resulting polycarbonate resin had an Mw of 35,000 and a Tg of 133°C. It also had a refractive index of 1.534 and an Abbe number of 56.6. Its total light transmittance was 90%. Its saturated water absorption was 0.32%, and its saturated water absorption expansion was 0.034%.

The present invention aims to provide a high-Abbe-number polycarbonate resin with a small difference in water absorption expansion coefficient compared to a polycarbonate resin with a high refractive index and a low Abbe number. The following shows the water absorption (%) and water absorption expansion coefficient (%) of two resins (Object 1 and Object 2) used for lamination during lens formation, as well as a high-Abbe-number resin (Comparative Example 1).

＜Subject 1＞

The water absorption (%) and water absorption expansion (%) of a low Abbe number bisphenol A polycarbonate resin (molecular weight Mw = 30,000, manufactured by Mitsubishi Gas Chemical Co., Ltd., H-4000) were measured. The results are shown in Tables 1 and 2.

<Comparative Example 1>

Using a high Abbe number cycloolefin polymer resin (molecular weight Mw = 140,000, ZEONEX 330R manufactured by Zeon Corporation of Japan), the water absorption (%) and water absorption expansion (%) were measured. The results are shown in Tables 1 and 2.

＜Object 2＞

Using a low Abbe number optical polycarbonate resin (molecular weight Mw = 27,000, EP5000 manufactured by Mitsubishi Gas Chemical Co., Ltd.), the water absorption (%) and water absorption expansion (%) were measured. The results are shown in Tables 1 and 2.

[Table 1]

[Table 2]

The results in Tables 1 and 2 show that the water absorption expansion coefficient of the low-Abbe-number polycarbonate resin of Example 2 (EP5000 manufactured by Mitsubishi Gas Chemical Corporation) is similar to that of the polycarbonate resin of Example 1. This demonstrates that the present invention achieves the goal of "providing a high-Abbe-number polycarbonate resin with a small difference in water absorption expansion coefficient compared to polycarbonate resins with a high refractive index and a low Abbe number." On the other hand, the high-Abbe-number resin of Comparative Example 1 exhibits a very low water absorption expansion coefficient, failing to achieve the aforementioned goal of the present invention.

Comparative Example 2

108 g (0.75 mol) of dimethyl fumarate, 128 g (0.97 mol) of dicyclopentadiene, and 300 g of p-xylene were placed in an autoclave, and the atmosphere was purged with nitrogen. The autoclave's internal temperature was then raised to 180°C, and the reaction was allowed to proceed at this temperature with stirring for 20 hours. After the reaction, 6 g of activated carbon carrying 10% palladium was added, and the atmosphere was purged with hydrogen. Hydrogen gas (21 MPa) was then added, and the reaction was allowed to proceed at 80°C with stirring for 1 hour. The reaction mixture was distilled under reduced pressure, and the residue was recrystallized from ethanol to obtain dimethyl perhydro-1,4:5,8-dimethyldimethylnaphthalene dicarboxylate. To a 300 mL autoclave, 52 g of dimethyl perhydro-1,4:5,8-dimethyldimethylnaphthalene dicarboxylate, 5 g of copper-chromium oxide (N-203-SD, manufactured by Nikko Chemical Co., Ltd.), and 100 mL of 1,4-dioxane were placed. The system was then purged with hydrogen, and hydrogen was added, followed by reaction at 200°C for 20 hours at a pressure of 30 MPa. After the reaction, 1,4-dioxane was removed, and the resulting white powder was recrystallized from ethyl acetate to yield perhydro-1,4:5,8-dimethanolnaphthalene-2,3-dimethanol, represented by the following structural formula.

Here, 30.90 g (0.139 mol) of the obtained perhydro-1,4:5,8-dimethanolnaphthalene-2,3-dimethanol, 29.80 g (0.139 mol) of diphenyl carbonate, and 0.09 mg (1.1 μmol) of sodium bicarbonate were placed in a 300 mL reactor equipped with a stirrer and a distillation device. The mixture was heated and stirred at 215°C for 1 hour under a nitrogen atmosphere of 760 Torr. The transesterification reaction was initiated at 200°C using an oil bath. Stirring began 5 minutes after the reaction began, and after 20 minutes, the pressure was reduced from 760 Torr to 200 Torr over 10 minutes. While reducing the pressure, the temperature was heated to 210°C. 70 minutes after the reaction began, the temperature was raised to 220°C. 80 minutes later, the pressure was reduced to 150 Torr over 30 minutes. The temperature was then raised to 240°C, the pressure was reduced to 1 Torr, and the reaction was maintained for 10 minutes to produce a polycarbonate resin.

The obtained polycarbonate resin was molded into a No. 1 test piece in accordance with Japanese Industrial Standard K7113, and the tensile elongation at yield was measured (tensile rate 2 mm/min). The tensile elongation at yield of the polycarbonate resin obtained in Comparative Example 2 was 51%, whereas the tensile elongation at yield of the polycarbonate resin obtained in Example 3 was 150%.

Industrial applicability

The present invention enables the production of excellent high-Abbe-number optical lenses. The optical lenses of the present invention can be injection molded with high productivity and affordability, making them extremely useful in applications such as cameras, telescopes, binoculars, and television projectors, where expensive high-Abbe-number glass lenses have traditionally been used. Furthermore, since the difference in water absorption between high-Abbe-number and low-Abbe-number lenses is minimized, they are particularly suitable for small optical lens units. Furthermore, the present invention enables the simple production of high-Abbe-number aspheric lenses, which are technically difficult to manufacture in glass lenses, through injection molding, making them extremely useful.

Claims (11)

1. A polycarbonate resin comprising the constituent units shown in the following general formula (1), In general formula (1), R is H, _CH3 or _{C2H5 .} The polycarbonate resin has a weight-average molecular weight of 5,000 to 300,000 and a glass transition temperature of 95 to 180°C. 2. The polycarbonate resin according to claim 1, characterized in that: A mixture comprising the isomer of the _-CH2O- group of the general formula (1) with the -CH2O- group at the 6-position (2, 6-position isomer) and the isomer of the _-CH2O- group of the general formula (1) with the -CH2O- group at the 7-position (2, 7-position isomer). 3. The polycarbonate resin according to claim 2, characterized in that: The ratio of the isomer at positions 2 and 6 to the isomer at positions 2 and 7 is 1.0:99.0 to 99.0:1.0 by mass. 4. The polycarbonate resin according to any one of claims 1 to 3, characterized in that: The water absorption swelling rate of polycarbonate resin is 0.01-0.5%. 5. The polycarbonate resin according to any one of claims 1 to 3, characterized in that: The Abbe number of polycarbonate resin is 25 or higher. 6. The polycarbonate resin according to any one of claims 1 to 3, characterized in that: The glass transition temperature of polycarbonate resin is 110–160℃. 7. The polycarbonate resin according to any one of claims 1 to 3, characterized in that: The weight-average molecular weight of polycarbonate resin is 5,000 to 50,000. 8. An optical lens obtained by molding the polycarbonate resin according to any one of claims 1 to 7. 9. The method for manufacturing the polycarbonate resin according to claim 1, characterized in that: The process includes reacting a diol compound represented by the following general formula (2) with a diester carbonate. In general formula ₍ 2), R is H, _CH3 or _C2H5 . 10. The method for manufacturing polycarbonate resin according to claim 9, characterized in that: The diol compound comprises a mixture of isomers of the general formula (2) with the _-CH2OH group at the 6-position (2, 6-position isomers) and isomers of the general formula (2) with the _-CH2OH group at the 7-position (2, 7-position isomers): 11. The method for manufacturing polycarbonate resin according to claim 10, characterized in that: The ratio of the isomer at positions 2 and 6 to the isomer at positions 2 and 7 is 1.0:99.0 to 99.0:1.0 by mass.