JP7820172B2 - Polycarbonate resin and molded products made from it - Google Patents

Description

The present invention relates to a polycarbonate resin that has excellent scratch resistance, heat resistance, and moldability, and to a molded article made from the same.

Polycarbonate resin is an engineering plastic that is used in a wide range of applications, including electrical and electronic equipment housings, automotive interior and exterior parts, building materials, furniture, musical instruments, and miscellaneous goods, due to its excellent transparency, impact resistance, heat resistance, and dimensional stability. Furthermore, compared to inorganic glass, its lower specific gravity allows for lighter weight and is highly manufacturable, making it suitable for use in automobile windows, etc.

Furthermore, sheets and films made from polycarbonate resin are widely used as various display devices and protective parts for automobile interiors by undergoing additional secondary processing such as coating, lamination, and surface modification.

However, when uncoated polycarbonate resin is measured in accordance with JIS K5600-5-4, General Test Methods for Paints - Part 5: Mechanical Properties of Coatings - Section 4: Scratch Hardness (Pencil Method), the pencil hardness of polycarbonate resin is only about 2B, which poses an issue for uncoated materials, as their surface is easily scratched.

As a solution, it is known to use copolymer polycarbonate resins with high surface hardness (see, for example, Patent Document 1). Also described is a method of producing polycarbonates or copolycarbonates with 2,2-bis(4-hydroxy-3-methylphenyl)propane as a structural unit (see, for example, Patent Documents 2 to 6). While these polycarbonate resins offer improved surface hardness, they suffer from the drawback of being inferior in heat resistance compared to polycarbonate resins.

Furthermore, Patent Document 7 describes a method for producing polycarbonates and copolycarbonates using 2,2-bis(4-hydroxy-3-methylphenyl)fluorene as a structural unit, proposing that this is effective in achieving high pencil hardness and high heat resistance. However, introducing structural units with a rigid structure to increase scratch resistance increases the glass transition temperature and reduces moldability, and so there is a problem in that 2,2-bis(4-hydroxy-3-methylphenyl)fluorene cannot be introduced as a structural unit in high proportions.

The present invention aims to solve these problems by providing a polycarbonate resin with excellent scratch resistance, heat resistance, and moldability, and a molded article made from the same.

Patent No. 5173803 Japanese Unexamined Patent Publication No. 64-069625 Japanese Patent Application Publication No. 08-183852 Japanese Patent Application Publication No. 08-034846 Japanese Patent Application Laid-Open No. 2002-117580 Patent No. 3768903 International Publication No. 2017/073508

The problem that this invention aims to solve is to provide a polycarbonate resin that is scratch-resistant and has excellent heat resistance and moldability, as well as a molded article made from the same.

As a result of extensive research aimed at achieving this goal, the inventors discovered that a polycarbonate resin with a specific structure could solve the above-mentioned problems, leading to the completion of the present invention. Specifically, the present invention is as follows:

<Aspect 1>
A polycarbonate resin whose main repeating units include a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B), and the molar ratio (A:B) of the repeating unit (A) to the repeating unit (B) is in the range of 5 or more but less than 40:95 or less but more than 60.

(In the formula, ^R1 and ^R2 each independently represent a hydrogen atom, a substituent having 1 to 20 carbon atoms which may contain an aromatic group, or a halogen atom; U represents a single bond or a divalent linking group; ^L1 and ^L2 each independently represent a divalent linking group; j and k each independently represent an integer of 1 to 4; and m and n each independently represent 0 or 1.)

<Aspect 2>
The polycarbonate resin according to embodiment 1, wherein m and n are 0 in formula (B).
<Aspect 3>
The polycarbonate resin according to embodiment 1, wherein m and n are 1 in formula (B).
<Aspect 4>
Aspect 4. The polycarbonate resin according to any one of Aspects 1 to 3, which has an indentation hardness measured in accordance with ISO/TS 19278 of 200 to 450 (N/mm ² ).
Aspect 5
A polycarbonate resin according to any one of Aspects 1 to 4, which has a pencil hardness of F or more as measured in accordance with JIS K5600.
Aspect 6
6. The polycarbonate resin according to any one of aspects 1 to 5, having a glass transition temperature of 120 to 180°C.
Aspect 7
7. The polycarbonate resin according to any one of Aspects 1 to 6, having a specific viscosity of 0.12 to 0.45.
Aspect 8
A molded article obtained by injection molding the polycarbonate resin according to any one of Aspects 1 to 7.
<Aspect 9>
A sheet or film obtained by extrusion molding the polycarbonate resin according to any one of Aspects 1 to 7.
<Aspect 10>
An automobile interior part using the molded article of embodiment 8 or the sheet or film of embodiment 9.

The polycarbonate resin of the present invention and molded articles made from it have excellent scratch resistance, heat resistance, and moldability, making them suitable for use in automotive interior parts. Therefore, the industrial benefits they offer are exceptional.

1 is ^{a 1} H NMR of the polycarbonate resin obtained in Example 1. 1 is ^{a 1} H NMR of the polycarbonate resin obtained in Example 2. 1 is ^{a 1} H NMR of the polycarbonate resin obtained in Example 3. 1 is a graph showing test force-depth of polycarbonate resins of Example 3 and Comparative Examples 2 and 3.

The present invention will now be described in more detail.

<Polycarbonate resin>
The polycarbonate resin of the present invention is a polycarbonate resin whose main repeating units include a repeating unit (A) represented by the following formula (A) and a repeating unit (B) represented by the following formula (B), and the molar ratio (A:B) of the repeating unit (A) to the repeating unit (B) is in the range of 5 or more but less than 40:95 or less but more than 60:

(In the formula, ^R1 and ^R2 each independently represent a hydrogen atom, a substituent having 1 to 20 carbon atoms which may contain an aromatic group, or a halogen atom; U represents a single bond or a divalent linking group; ^L1 and ^L2 each independently represent a divalent linking group; j and k each independently represent an integer of 1 or greater; and m and n each independently represent 0 or 1.)

In the formula (B), R ¹ and R ² each independently represent a hydrogen atom, a halogen atom, or a substituent having 1 to 20 carbon atoms which may contain an aromatic group, and are preferably a hydrogen atom, a methyl group, an isopropyl group, a tert-butyl group, a cyclohexyl group, or a phenyl group, more preferably a hydrogen atom, a methyl group, a tert-butyl group, or a cyclohexyl group, and still more preferably a hydrogen atom or a methyl group.

In formula (B), j and k each independently represent an integer of 1 to 4, preferably an integer of 1 or 2, and more preferably 1.

In formula (B), L ¹ and L ² each independently represent a divalent linking group, and are preferably alkylene groups having 1 to 12 carbon atoms, more preferably alkylene groups having 1 to 4 carbon atoms, and even more preferably ethylene groups. By adjusting the lengths of the linking groups ^{L 1} and L ² , the glass transition temperature (Tg) of the resin can be adjusted.

In the formula (B), m and n each independently represent 0 or 1.
In the formula (B), U represents a single bond or a divalent linking group.
U is preferably represented by the following formula (1).

(In formula (1), R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ and R ¹⁸ each independently represent a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 14 carbon atoms and an aralkyl group having 7 to 20 carbon atoms; R ¹⁹ and R ²⁰ each independently represent a group selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, a cycloalkoxy group having 6 to 20 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aralkyloxy group having 7 to 20 carbon atoms, a nitro group, an aldehyde group, a cyano group, and a carboxy group; when there are a plurality of 20, they may be the same or different; c is an integer from 1 to 10, and d is an integer from 4 to 7.
In addition, the formula (B) excludes the formula (A).

The polycarbonate resin of the present invention is obtained by reacting a dihydroxy compound with a carbonate precursor. Reaction methods include interfacial polycondensation, melt transesterification, solid-phase transesterification of carbonate prepolymers, and ring-opening polymerization of cyclic carbonate compounds. In the case of interfacial polycondensation, a monohydric phenol end-stopper is typically used. The polycarbonate may also be a branched polycarbonate obtained by polymerizing a trifunctional component, or a copolymer polycarbonate obtained by copolymerizing an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and a vinyl monomer.

In reactions using phosgene as a carbonate precursor, the reaction is usually carried out in the presence of an acid binder and a solvent. Examples of acid binders include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, or amine compounds such as pyridine. Examples of solvents include halogenated hydrocarbons such as methylene chloride and chlorobenzene. A catalyst such as a tertiary amine or quaternary ammonium salt can also be used to promote the reaction. The reaction temperature is usually 0 to 40°C, and the reaction time is several minutes to 5 hours.

Monofunctional phenols commonly used as end-capping agents can be used. In particular, in reactions using phosgene as the carbonate precursor, monofunctional phenols are commonly used as end-capping agents to adjust molecular weight. Furthermore, the resulting polycarbonate resin has superior thermal stability compared to those without the end-capping, since the ends are capped with groups based on monofunctional phenols. Specific examples of monofunctional phenols include phenol, m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, 1-phenylphenol, 2-phenylphenol, p-tert-butylphenol, p-cumylphenol, isooctylphenol, and p-long-chain alkylphenols.

Transesterification reactions using, for example, a carbonate diester as a carbonate precursor are carried out by heating and stirring a predetermined proportion of aromatic dihydroxy components with the carbonate diester under an inert gas atmosphere, and distilling off the resulting alcohol or phenol. The reaction temperature varies depending on the boiling point of the resulting alcohol or phenol, but is typically in the range of 120 to 300°C. The reaction is completed by reducing the pressure from the beginning of the reaction to distill off the resulting alcohol or phenol. A catalyst typically used in transesterification reactions can also be used to promote the reaction. Examples of carbonate diesters used in the transesterification reaction include diphenyl carbonate, dinaphthyl carbonate, bis(diphenyl)carbonate, dimethyl carbonate, diethyl carbonate, and dibutyl carbonate. Of these, diphenyl carbonate is particularly preferred.

The polycarbonate resin of the present invention includes a polyester carbonate copolymerized with an aromatic or aliphatic (including alicyclic) bifunctional carboxylic acid. The aliphatic bifunctional carboxylic acid is preferably an α,ω-dicarboxylic acid. Preferred examples of aliphatic bifunctional carboxylic acids include linear saturated aliphatic dicarboxylic acids such as sebacic acid (decanedioic acid), dodecanedioic acid, tetradecanedioic acid, octadecanedioic acid, and icosane dicarboxylic acid, as well as alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. These carboxylic acids may be copolymerized to the extent that the objectives are not impaired.

The polycarbonate resin of the present invention has a molar ratio (A:B) of the main repeating unit (A) to the repeating unit (B) in the range of 5 or more and less than 40:95 or less and more than 60. Polycarbonate resins of the present invention having a molar ratio (A:B) in the above range are preferred because they exhibit an excellent balance of scratch resistance, heat resistance, and moldability. Furthermore, because the repeating unit (A) is bulky around the hydroxy group, the above range is also preferred from the standpoint of reactivity. The molar ratio (A:B) is preferably in the range of 8 or more and 38:92 or less and 62 or more, and more preferably in the range of 10 or more and 36:90 or less and 64 or more. The main repeating unit refers to the sum of the repeating units (A) and (B) of all repeating units being 90 mol% or more, preferably 95 mol% or more, and more preferably 100 mol%.

Additives such as heat stabilizers, plasticizers, light stabilizers, polymerized metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, antioxidants, ultraviolet absorbers, and mold release agents can also be blended into the polycarbonate resin of the present invention as needed.

<Physical properties of polycarbonate resin>
The polycarbonate resin of the present invention preferably has an indentation hardness of 200 to 450 (N/mm ² ), more preferably 210 to 440 (N/mm 2 ), even more preferably 220 to 430 (N/mm ² ), and particularly preferably 225 to 420 (N/mm ² ), measured in accordance with ^ISO /TS 19278. When the indentation hardness is within the above range, the molded article will have excellent scratch resistance.

The polycarbonate resin of the present invention preferably has a pencil hardness of F or higher, more preferably H or higher, and even more preferably 2H or higher, as measured in accordance with JIS K5600-5-4, General Testing Methods for Coatings - Part 5: Mechanical Properties of Coating Films - Section 4: Scratch Hardness (Pencil Method). A pencil hardness within this range is preferred because scratches are less likely to occur on the surface of the molded product.

Pencil hardness, a commonly used index for measuring a material's scratch resistance, is a discrete index with a range, so it is not possible to compare the hardness of materials with the same pencil hardness (2H), for example. Therefore, by using indentation hardness, which allows for quantitative evaluation, as an index, it is possible to evaluate the degree of hardness even for materials with the same pencil hardness.

The polycarbonate resin of the present invention may have a glass transition temperature (Tg) of 120°C or higher, 125°C or higher, 130°C or higher, 135°C or higher, or 140°C or higher, or 180°C or lower, 175°C or lower, 170°C or lower, 165°C or lower, or 160°C or lower. It is preferably 120 to 180°C, more preferably 125 to 170°C, even more preferably 130 to 165°C, and particularly preferably 130 to 160°C. A glass transition temperature within the above range is preferred because it provides an excellent balance between heat resistance and moldability.

The specific viscosity of the polycarbonate resin of the present invention is preferably 0.12 to 0.45, more preferably 0.14 to 0.42, and even more preferably 0.16 to 0.40. A specific viscosity within the above range is preferred because it provides an excellent balance between moldability and mechanical strength.

The specific viscosity is measured by measuring the specific viscosity (η _SP ) at 20° C. of a solution prepared by dissolving 0.7 g of polycarbonate resin in 100 ml of methylene chloride using an Ostwald viscometer, and calculating the specific viscosity from the following formula.
Specific viscosity (η _SP )=(t−t ₀ )/t ₀
( _t0 is the number of seconds it takes for methylene chloride to fall, and t is the number of seconds it takes for the sample solution to fall.)

<Raw materials for polycarbonate resin>
(Diol component of formula (A))
The diol component used as the raw material of formula (A) is a diol component represented by the following formula (a).

The dihydroxy compound components that serve as raw materials for the compound of formula (B) of the present invention are shown below.
In the formula (B), when m and n are 0, the dihydroxy compound components used as raw materials for the formula (B) of the present invention include 4,4'-biphenol, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,1-bis(4-hydroxyphenyl)-3,3,5 Examples of the cyclohexane-3-methyl-4-hydroxyphenyl ester include 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 1,1-bis(3-methyl-4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxyphenyl)sulfide, and bis(4-hydroxy-3-methylphenyl)sulfide, with 2,2-bis(3-methyl-4-hydroxyphenyl)propane and 1,1-bis(3-methyl-4-hydroxyphenyl)cyclohexane being particularly preferred. These may be used alone or in combination of two or more.

When m and n are 1 in formula (B) above, examples of the dihydroxy compound component serving as the raw material for formula (B) of the present invention include 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, and 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, with 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene and 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene being particularly preferred. These may be used alone or in combination of two or more.

<Polycarbonate resin molded products, automotive interior parts>
The polycarbonate resin of the present invention can be molded into desired articles by injection molding, injection compression molding, injection blow molding, two-color molding, extrusion molding, blow molding, or other methods.

The polycarbonate resin of the present invention may be produced by any method, including injection molding to produce molded articles of various shapes. Furthermore, sheet- or film-shaped molded articles may also be produced by melt extrusion, solution casting, or other methods. A specific example of a melt extrusion method involves feeding a fixed amount of polycarbonate resin into an extruder, melting it by heating, and extruding the molten resin from the tip of a T-die onto a mirror-finished roll in the form of a sheet. The resin is then drawn off while being cooled by multiple rolls, and once solidified, it is either cut to an appropriate size or wound up. A specific example of a solution casting method involves casting a solution of polycarbonate resin in methylene chloride (concentration: 5% to 40%) from a T-die onto a mirror-polished stainless steel plate, passing it through a temperature-controlled oven in stages to peel off the sheet, removing the solvent, and then cooling and winding it up.

Polycarbonate resin can also be made into a laminate. Any method can be used to produce a laminate, with thermocompression bonding or co-extrusion being particularly preferred. Any method can be used for thermocompression bonding, but preferred methods include thermocompression bonding of a polycarbonate resin sheet using a laminator or press, or thermocompression bonding immediately after extrusion. In particular, a method of thermocompression bonding continuously to a polycarbonate resin sheet immediately after extrusion is industrially advantageous.

The polycarbonate resin of the present invention also has excellent scratch resistance and is therefore suitable for use as automotive interior parts. Examples of automotive interior parts include interior lighting lamp lenses, display meter covers, meter dial plates, various switch covers, display covers, heat control panels, instrument panels, center clusters, center panels, room lamp lenses, various display devices such as head-up displays, protective parts, and translucent parts. Furthermore, because the automotive interior parts of the present invention have the above-mentioned properties, they have the advantage that the polycarbonate resin molded products can be used as they are without the need for coating treatment.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Evaluation was carried out according to the following methods.
(1) Polymer Composition Ratio The polymer composition ratio of each component was calculated by measuring the resulting resin by ¹ H NMR using a JNM-ECZ400S manufactured by JEOL Ltd. CDCl ₃ was used as the solvent.
(2) Specific viscosity (η _SP )
The specific viscosity (η _SP ) calculated by the following formula was determined using an Ostwald viscometer from a solution prepared by dissolving 0.7 g of a sample in 100 ml of methylene chloride at 20°C.
Specific viscosity (η _SP )=(t−t ₀ )/t ₀
[ _t0 is the number of seconds for methylene chloride to fall, and t is the number of seconds for the sample solution to fall]
(3) Glass transition temperature (Tg)
The obtained resin was measured at a temperature rising rate of 20° C./min using a differential thermal and thermogravimetric simultaneous analyzer Discovery SDT650 manufactured by TA Instruments. The measurement was performed using a sample of about 5 mg.
(4) Indentation hardness (Hit)
Based on ISO/TS 19278, a dynamic ultra-microhardness tester (Shimadzu Corporation, model DUH-210S) was used to measure the relationship between the load and the indentation depth on the surface of the resin plate in real time, and the indentation hardness (N/mm ² ) was measured.

(Measurement conditions)
Measurement indenter: Berkovich indenter (made of diamond)
Test force: 500 mN
Minimum test force: 4.9 mN
Loading/unloading time: 30sec
Load holding time: 40sec
Unloading holding time: 0sec
Number of tests: 5
(Method for calculating indentation hardness)
Indentation hardness (Hit) is a measure of resistance to semi-permanent deformation or damage. Indentation hardness is calculated by the following formula:
Hit= _Fmax /Ap
F _max : Maximum test force Ap: Projected area where the indenter is in contact with the test piece Ap = 23.96 × hc ² (in the case of a triangular pyramidal indenter (115°))
hc=h _max -ε(h _max -hr)
ε = 3/4 (in the case of a triangular pyramid)
hr: Intercept of the tangent to the unloading curve at _Fmax on the test force-depth curve intersects with the depth axis

(5) Pencil Hardness Based on JIS K5600, a line was drawn on the surface of a resin plate in a thermostatic chamber at an ambient temperature of 23°C with a pencil held at a 45° angle and a load of 750 g applied, and the surface condition was evaluated visually.
Load: 750g
Measurement speed: 50mm/min
Measurement distance: 7 mm
Pencil: Mitsubishi Pencil Hi-uni

Reference Example 1 Synthesis of BCHP-FL 15.00 g of fluorenone, 30.81 g of 2-cyclohexylphenol, 1.42 g of phosphotungstic acid, 0.49 g of octanethiol, and 100 ml of toluene were charged into a flask equipped with a stirrer, a condenser, a Dean-Stark tube, and a thermometer, and the mixture was reacted at 100°C and 50 kPa for 11 hours. After the reaction, the mixture was diluted with 300 ml of toluene and then washed five times with distilled water. The organic layer after washing was concentrated, and 400 ml of acetone was added to the concentrated residue, resulting in the precipitation of white crystals of 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene (hereinafter sometimes abbreviated as BCHP-FL). The crystals were collected by filtration and dried under reduced pressure at 70°C for 4 hours, yielding 29.9 g of BCHP-FL (yield 70%).

[Example 1]
A reactor equipped with a thermometer, a stirrer, and a reflux condenser was charged with 80.81 parts by mass of ion-exchanged water and 35.91 parts by mass of 25% aqueous sodium hydroxide solution, and 12.95 parts by mass of 2,2-bis(3-methyl-4-hydroxyphenyl)propane (hereinafter sometimes abbreviated as BPC) as a diol, 2.91 parts by mass of BCHP-FL, and 0.032 parts by mass of hydrosulfite were dissolved therein. Then, 71.55 parts by mass of methylene chloride was added, and 7.50 parts by mass of phosgene was blown in over 70 minutes at 16 to 24 ° C. with stirring. Thereafter, 4.49 parts by mass of 25% aqueous sodium hydroxide solution, a solution in which 0.253 parts by mass of p-tert-butylphenol was dissolved in 2.53 parts by mass of methylene chloride, and 0.003 parts by mass of triethylamine were added, and the mixture was stirred to form an emulsion. While stirring, 0.014 parts by mass of triethylamine was added while the reaction solution was at 28°C, and stirring was continued for 1 hour at a temperature of 26 to 31°C to terminate the reaction. After the reaction was completed, the organic phase was separated, diluted with methylene chloride, and repeatedly washed with ion-exchanged water. When the washings became neutral, hydrochloric acid was added. The mixture was then repeatedly washed with ion-exchanged water until the conductivity of the aqueous phase was nearly the same as that of the ion-exchanged water, yielding a methylene chloride solution of polycarbonate. The resulting methylene chloride solution was then added dropwise to warm water maintained at 50 to 80°C, and the solvent was evaporated to obtain a flaky solid. The resulting solid was filtered and dried at 120°C for 24 hours to obtain white flake-like polycarbonate of Example 1. The properties of the resulting resin are shown in Table 1.

[Example 2]
A reaction vessel equipped with a thermometer, a stirrer, and a reflux condenser was charged with 26.60 parts by mass of pyridine and 143.10 parts by mass of methylene chloride as an acid binder and a solvent, respectively. 5.82 parts by mass of BCHP-FL and 11.51 parts by mass of BPC as diols, and 0.253 parts by mass of p-tert-butylphenol as an end-terminator were dissolved in the reaction vessel, and then 7.50 parts by mass of phosgene was blown into the mixture over approximately 70 minutes at 15 to 26°C with stirring. After the phosgene blowing was completed, the mixture was stirred at 26 to 35°C for 60 minutes, and the reaction was then terminated.

After the reaction was complete, the product was diluted with methylene chloride and washed with ion-exchanged water. Hydrochloric acid was added to acidify the solution, followed by water washing. Further water washing was repeated until the conductivity of the aqueous phase was approximately the same as that of the ion-exchanged water, yielding a methylene chloride solution of polycarbonate. The resulting methylene chloride solution was then added dropwise to warm water maintained at 50-80°C, and the solvent was evaporated to yield a flaky solid. The resulting solid was filtered and dried at 120°C for 24 hours to yield white flakes of polycarbonate of Example 2. The properties of the resulting resin are shown in Table 1.

[Comparative Example 1]
A polycarbonate resin was produced in the same manner as in Example 1, except that BCHP-FL was changed to 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (hereinafter sometimes abbreviated as "BCF"). The properties of the obtained polycarbonate resin are shown in Table 1.

The polycarbonate resins obtained in Examples 1 and 2 exhibited a smaller increase in glass transition temperature with increasing in indentation hardness compared to Comparative Example 1, and demonstrated excellent scratch resistance and a high level of balance between heat resistance and moldability.

[Example 3]
15.40 parts by mass of BCHP-FL, 19.73 parts by mass of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (hereinafter sometimes abbreviated as BPEF), 16.23 parts by mass of diphenyl carbonate (hereinafter sometimes abbreviated as DPC), and 3.15 x ¹⁰ parts by mass of sodium bicarbonate at a concentration of 60 mmol/L as a catalyst were added, and the mixture was heated to 180°C under a nitrogen atmosphere and melted. The pressure was then reduced to 20 kPa over 5 minutes. The temperature was raised to 240°C at a rate of 60°C/hr, and after the phenol outflow rate reached 70%, the pressure was reduced to 40 kPa/hr. The polymerization reaction was carried out until the specified power was reached, and the resin was removed from the flask after the reaction was completed. The properties of the resulting polycarbonate resin are shown in Table 2.

[Comparative Examples 2 to 3]
A polycarbonate resin was produced in the same manner as in Example 3, except that BCHP-FL was changed to BCF and the ratio of BCF to BPEF was changed. The properties of the obtained polycarbonate resin are shown in Table 2.

The polycarbonate resin obtained in Example 3 exhibited a smaller increase in glass transition temperature with increasing in indentation hardness compared to Comparative Examples 2 and 3, and was found to have excellent scratch resistance and a high level of balance between heat resistance and moldability.

The polycarbonate resin of the present invention has excellent scratch resistance, heat resistance, and moldability, so it does not require coating treatment and can be used for automotive interior parts such as interior lighting lamp lenses, display meter covers, meter dial plates, various switch covers, display covers, heat control panels, instrument panels, center clusters, center panels, room lamp lenses, various display devices such as head-up displays, protective parts, and translucent parts.

Claims (8)

A polycarbonate resin containing a repeating unit (A) represented by the following formula (A) as a main repeating unit and a repeating unit (B) derived from the following formula (B-1) or (B-2) , wherein the molar ratio (A:B) of the repeating unit (A) to the repeating unit (B) is in the range of 5 or more and less than 40:95 or less and more than 60:
2. The polycarbonate resin according to claim 1 , which has an indentation hardness measured in accordance with ISO/TS 19278 of 200 to 450 (N/mm ² ). 3. The polycarbonate resin according to claim 1 , which has a pencil hardness of F or more as measured in accordance with JIS K5600. The polycarbonate resin according to any one of claims 1 to 3 , which has a glass transition temperature of 120 to 180°C. 5. The polycarbonate resin according to claim 1 , which has a specific viscosity of 0.12 to 0.45. A molded article obtained by injection molding the polycarbonate resin according to any one of claims 1 to 5 . A sheet or film obtained by extrusion molding the polycarbonate resin according to any one of claims 1 to 5 . An automobile interior part using the molded article of claim 6 or the sheet or film of claim 7 .