Polycarbonate resin, resin solution, and film

Abstract

A polycarbonate resin provided according to one embodiment of the present invention comprises a constituent unit (A) derived from a monomer represented by formula (1), a constituent unit (B) derived from a monomer represented by formula (2), a constituent unit (C) derived from a monomer represented by formula (3), and / or a constituent unit (D) derived from a monomer represented by formula (4).

Description

Polycarbonate resin, resin solution and film

[0001] The present invention relates to a polycarbonate resin, a resin solution containing the resin, and a film produced using the resin solution.

[0002] Polycarbonate resins are widely used in electrical and electronic equipment, office automation equipment, optical media, automotive parts, building materials, and the like due to their excellent mechanical strength, heat resistance, electrical properties, dimensional stability, flame retardancy, transparency, and the like (see, for example, Patent Documents 1 to 7). When molding polycarbonate resins into films, the manufacturing methods are broadly divided into extrusion molding and wet molding. When molding polycarbonate resins with excellent heat resistance, i.e., high glass transition temperatures (Tg), into films, wet molding is generally employed. To efficiently wet mold such resins, it is preferable to use a relatively low-boiling organic solvent and dissolve the resin in the solvent at a high concentration (e.g., 20% by mass or more relative to the solvent). Traditionally, halogenated solvents have been used as low-boiling solvents for polycarbonate resins with high glass transition temperatures. However, in recent years, environmental considerations have led to a demand for the use of non-halogenated solvents.

[0003] Known examples of such low-boiling, non-halogenated solvents include ketone solvents and ester solvents. However, conventionally known polycarbonate resins with high glass transition temperatures often have poor solubility in these solvents. Therefore, using non-halogenated solvents in consideration of the environment has led to the problem of poor molding efficiency in wet molding. To address this issue, high-Tg polycarbonate resins with improved solubility, particularly in low-boiling, non-halogenated solvents, have been proposed (Patent Document 8). Furthermore, there is currently a demand for polycarbonate resins that are not only solvent-soluble as described above, but also available at lower prices and in stable supply.

[0004] Japanese Patent Application Laid-Open No. 63-89540 Japanese Patent Application Laid-Open No. 2-99521 Japanese Patent Application Laid-Open No. 2-128336 Japanese Patent Application Laid-Open No. 2017-031245 Japanese Patent Application Laid-Open No. 2011-246583 Japanese Patent Application Laid-Open No. 2010-143950 Japanese Patent Application Laid-Open No. 2011-027940 International Publication No. 2020 / 250732

[0005] An object of the present invention is to provide a polycarbonate resin having excellent solvent solubility.

[0006] The present inventors have conducted extensive research into polycarbonate resins using bisphenol A (hereinafter also referred to as "BPA"), a raw material that is inexpensive and can be stably supplied. Polycarbonate resins using BPA as a raw material have traditionally been thought to be low-cost but have poor solvent solubility. However, contrary to this knowledge, the present inventors have discovered that polycarbonate resins with excellent solvent solubility can be produced using BPA as the main raw material. The present invention is, for example, as follows. [1] A polycarbonate resin comprising a structural unit (A) derived from a monomer represented by the following formula (1), a structural unit (B) derived from a monomer represented by the following formula (2), and a structural unit (C) derived from a monomer represented by the following formula (3) and / or a structural unit (D) derived from a monomer represented by the following formula (4), wherein, relative to the total of the structural units (A), (B), (C), and (D) constituting the resin, the proportion of the structural unit (A) is 50 to 65 mass%, the proportion of the structural unit (B) is 10 to 30 mass%, and the total proportion of the structural units (C) and (D) is 5 to 30 mass%. [2] The polycarbonate resin according to [1], which contains a structural unit (A) derived from a monomer represented by formula (1), a structural unit (B) derived from a monomer represented by formula (2), and a structural unit (C) derived from a monomer represented by formula (3). [3] The polycarbonate resin according to [1], which contains a structural unit (A) derived from a monomer represented by formula (1), a structural unit (B) derived from a monomer represented by formula (2), and a structural unit (D) derived from a monomer represented by formula (4). [4] The polycarbonate resin according to [1], which contains a structural unit (A) derived from a monomer represented by formula (1), a structural unit (B) derived from a monomer represented by formula (2), a structural unit (C) derived from a monomer represented by formula (3), and a structural unit (D) derived from a monomer represented by formula (4). [4-1] The polycarbonate resin according to any one of [1] to [4], which contains a structure derived from p-t-butylphenol at a terminal. [5] The polycarbonate resin according to any one of [1] to [4-1], having a viscosity average molecular weight (Mv) of 10,000 to 80,000. [6] The polycarbonate resin according to any one of [1] to [5], having a glass transition temperature (Tg) of 140 to 160°C. [7] A resin solution comprising a non-halogenated organic solvent and the polycarbonate resin according to any one of [1] to [6] dissolved in the non-halogenated organic solvent. [8] The resin solution according to [7], wherein the polycarbonate resin is contained in an amount of 20 mass% or more in the resin solution. [9] The resin solution according to [7] or [8], wherein the non-halogenated organic solvent is at least one of a ketone solvent and an ester solvent. [9-1] The resin solution according to [9], wherein the non-halogenated organic solvent is at least one of methyl ethyl ketone, ethyl acetate, ethyl carbitol acetate, and 2-methoxy-1-methylethyl acetate.

[10] A film produced using the resin solution according to any one of [7] to [9-1].

[11] A method for producing a film, comprising wet-molding the resin solution according to any one of [7] to [9-1].

[0007] According to the present invention, a polycarbonate resin having excellent solvent solubility can be provided.

[0008] Embodiments of the present invention will be described in detail below. According to one embodiment, the polycarbonate resin of the present invention contains a structural unit (A) derived from a monomer represented by the following formula (1), a structural unit (B) derived from a monomer represented by the following formula (2), a structural unit (C) derived from a monomer represented by the following formula (3) and / or a structural unit (D) derived from a monomer represented by the following formula (4). Based on the total of the structural units (A), (B), (C), and (D) constituting the resin, the proportion of the structural unit (A) is 50 to 65 mass%, the proportion of the structural unit (B) is 10 to 30 mass%, and the total proportion of the structural units (C) and (D) is 5 to 30 mass%.

[0009] The present inventors have found that polycarbonate resins having the above-described structure have excellent solvent solubility. To obtain a polycarbonate resin member with excellent heat resistance, a polycarbonate resin with a high glass transition temperature is used. When molding a polycarbonate resin with a high glass transition temperature, particularly in wet molding, it is preferable to use an organic solvent with a relatively low boiling point and dissolve the resin in the solvent at a high concentration (e.g., 20% by mass or more). This allows the polycarbonate resin to be molded efficiently.

[0010] While halogenated solvents have traditionally been used as low-boiling point solvents for polycarbonate resins with high glass transition temperatures, it is preferable to use non-halogenated solvents that do not contain halogens, due to environmental considerations. However, conventionally used polycarbonate resins with high glass transition temperatures have poor solvent solubility, particularly in non-halogenated solvents, which has posed a problem during the molding process. In response to this, the present inventors have discovered that polycarbonate resins according to embodiments of the present invention have excellent solvent solubility while maintaining a high glass transition temperature. The polycarbonate resins according to embodiments of the present invention are soluble in solvents at high concentrations and can therefore be efficiently molded, particularly in wet molding. Furthermore, they also exhibit excellent solubility in non-halogenated solvents, which has traditionally been a problem, making them preferable from an environmental perspective. Furthermore, the polycarbonate resins according to embodiments of the present invention also have excellent dissolution stability and can be stably stored for long periods in the form of a resin solution in which the resin is dissolved in a solvent. Stable storage for long periods in the form of a resin solution would be a major industrial advantage, as it would allow the resin solution to be prepared in advance and used only as needed each time. On the other hand, if cloudiness (resin precipitation) or the like occurs during storage, the resin concentration in the solution will change, which is undesirable. Therefore, if the resin solution can be stably stored for a long period of time without cloudiness or the like, it will be possible to efficiently provide a uniform product.

[0011] The market demands polycarbonate resins that have the above-mentioned properties, as well as lower prices and stable supply. Bisphenol A (BPA) is an example of a polycarbonate resin raw material that has desirable properties such as low cost, high quality, and stable supply. However, polycarbonate resins that use a large amount of BPA as a raw material are known to have poor solvent solubility. Despite this situation, polycarbonate resins according to embodiments have achieved high solvent solubility despite using a large amount of BPA as a raw material. Because polycarbonate resins according to embodiments use BPA as a primary raw material, they are low-cost and can be stably supplied to the market. That is, according to embodiments of the present invention, polycarbonate resins with excellent properties such as heat resistance, solvent solubility, and dissolution stability can be stably supplied at low prices. The present invention has been achieved contrary to previous knowledge that polycarbonate resins with high glass transition temperatures and polycarbonate resins that use a large amount of BPA as a raw material have poor solvent solubility, and is therefore extremely significant. Moreover, the polycarbonate resin according to the embodiment can be wet molded using a non-halogenated solvent, and therefore has the great industrial advantage of being low cost and environmentally friendly.

[0012] The reason why the polycarbonate resin according to the embodiment has excellent solvent solubility is not clear, but is presumed to be as follows. The polycarbonate resin according to the embodiment has a relatively low content of the structural units (C) and (D), which can contribute to improving the solvent solubility of the resin, and a relatively high content of the structural unit (A), which is not thought to contribute to improving solvent solubility. It is presumed that the excellent solvent solubility was achieved despite this configuration because the inclusion of three or more types of structural units increases the randomness of the polycarbonate chain structure, which contributes to improving solvent solubility.

[0013] The components, production method, physical properties, applications, etc. of the polycarbonate resin according to the embodiment will be described in detail below. [1] Polycarbonate Resin According to one embodiment, the polycarbonate resin of the present invention comprises a structural unit (A) derived from a monomer represented by the following formula (1) (hereinafter also referred to as "bisphenol A" or "BPA"), a structural unit (B) derived from a monomer represented by the following formula (2) (hereinafter also referred to as "bisphenol AP" or "BPAP"), a structural unit (C) derived from a monomer represented by the following formula (3) (hereinafter also referred to as "bisphenol C" or "BPC") and / or a structural unit (D) derived from a monomer represented by the following formula (4) (hereinafter also referred to as "4,4'-(4-methylpentane-2,2-diyl)diphenol" or "MIBK"). With respect to the total of the structural units (A), (B), (C), and (D) constituting the resin, the proportion of the structural unit (A) is 50 to 65% by mass, the proportion of the structural unit (B) is 10 to 30% by mass, and the total proportion of the structural units (C) and (D) is 5 to 30% by mass.

[0014] The proportion of the structural unit (A) relative to the total of the structural units (A), (B), (C), and (D) constituting the resin is preferably 50 to 64% by mass, more preferably 55 to 62% by mass, and may be, for example, 50 to 60% by mass. The proportion of the structural unit (B) relative to the total of the structural units (A), (B), (C), and (D) constituting the resin is preferably 10 to 25% by mass, more preferably 15 to 23% by mass, and may be, for example, 10 to 20% by mass. Because BPAP constituting the structural unit (B) has a substituent containing an aromatic ring, the rotational potential energy of the molecular chain is increased, which can contribute to an improvement in the glass transition temperature.

[0015] Either or both of the structural unit (C) and the structural unit (D) are contained in the polycarbonate resin. According to an embodiment containing both the structural unit (C) and the structural unit (D), a polycarbonate resin is provided that contains the structural unit (A) derived from a monomer represented by the above formula (1), the structural unit (B) derived from a monomer represented by the above formula (2), the structural unit (C) derived from a monomer represented by the above formula (3), and the structural unit (D) derived from a monomer represented by the above formula (4). Here, the proportion of the structural unit (A) is 50 to 65% by mass, preferably 50 to 64% by mass, more preferably 55 to 62% by mass, and may be, for example, 50 to 60% by mass, based on the total of the structural units (A), (B), (C), and (D) that constitute the resin. The proportion of the structural unit (B) is 10 to 30% by mass, preferably 10 to 25% by mass, more preferably 15 to 23% by mass, and may be, for example, 10 to 20% by mass, based on the total of the structural units (A), (B), (C), and (D) constituting the resin. The total proportion of the structural units (C) and (D) is preferably 10 to 25% by mass, more preferably 15 to 25% by mass, and may be, for example, 10 to 20% by mass, based on the total of the structural units (A), (B), (C), and (D) constituting the resin. As long as the total proportion of the structural units (C) and (D) is within the above range, the respective proportions of the structural units (C) and (D) are not particularly limited.

[0016] The polycarbonate resin according to the embodiment may not contain the structural unit (D). Therefore, according to another embodiment, a polycarbonate resin is provided that contains a structural unit (A) derived from a monomer represented by the above formula (1), a structural unit (B) derived from a monomer represented by the above formula (2), and a structural unit (C) derived from a monomer represented by the above formula (3). The proportion of the structural unit (A) relative to the total of the structural units (A), (B), and (C) constituting the resin is 50 to 65% by mass, preferably 50 to 64% by mass, more preferably 55 to 62% by mass, and may be, for example, 50 to 60% by mass. The proportion of the structural unit (B) relative to the total of the structural units (A), (B), and (C) constituting the resin is 10 to 30% by mass, preferably 10 to 25% by mass, more preferably 15 to 23% by mass, and may be, for example, 10 to 20% by mass. The proportion of the structural unit (C) relative to the total of the structural units (A), (B), and (C) that constitute the resin is 5 to 30% by mass, preferably 10 to 25% by mass, and more preferably 15 to 25% by mass, and may be, for example, 10 to 20% by mass.

[0017] The polycarbonate resin according to the embodiment may not contain the structural unit (C). Therefore, according to another embodiment, a polycarbonate resin is provided that contains a structural unit (A) derived from a monomer represented by the above formula (1), a structural unit (B) derived from a monomer represented by the above formula (2), and a structural unit (D) derived from a monomer represented by the above formula (4). The proportion of the structural unit (A) relative to the total of the structural units (A), (B), and (D) constituting the resin is 50 to 65% by mass, preferably 50 to 64% by mass, more preferably 55 to 62% by mass, and may be, for example, 50 to 60% by mass. The proportion of the structural unit (B) relative to the total of the structural units (A), (B), and (D) constituting the resin is 10 to 30% by mass, preferably 10 to 25% by mass, more preferably 15 to 23% by mass, and may be, for example, 10 to 20% by mass. The proportion of the structural unit (D) relative to the total of the structural units (A), (B), and (D) that constitute the resin is 5 to 30% by mass, preferably 10 to 25% by mass, and more preferably 15 to 25% by mass, and may be, for example, 10 to 20% by mass.

[0018] The polycarbonate resin according to the embodiment may have any of a random, block, and alternating copolymer structure. The polycarbonate resin according to the embodiment may contain structural units other than the structural units (A) to (D) described above. The total proportion of the structural units (A) to (D) in the polycarbonate resin is preferably 70 to 100% by mass, and more preferably 80 to 100% by mass, relative to the polycarbonate resin (100% by mass). By using such a proportion, the effects of the present invention can be more effectively exhibited.

[0019] Examples of other structural units include structural units derived from aliphatic dihydroxy compounds and structural units derived from aromatic dihydroxy compounds, which are generally used as structural units of polycarbonate resins.Furthermore, structural units derived from synthetic resins such as aromatic polyesters, aliphatic polyesters, polyamides, polystyrenes, polyolefins, acrylics, amorphous polyolefins, ABS, and AS, biodegradable resins such as polylactic acid and polybutylene succinate, and rubbers can also be mentioned.

[0020] [2] Method for Producing Polycarbonate Resin The method for producing a polycarbonate resin is not particularly limited, and it can be produced by a conventionally known method using a dihydroxy compound and a carbonate binder as raw materials. Examples include a method of directly reacting a dihydroxy compound with phosgene or the like (interfacial polymerization method, phosgene method), and a method of subjecting a dihydroxy compound to a transesterification reaction with a carbonate diester in a molten state (transesterification method, melting method).

[0021] The dihydroxy compound may be any of the compounds represented by the above formulas (1) to (4). If necessary, other dihydroxy compounds may be used in combination. When produced by interfacial polymerization, the dihydroxy compound is typically reacted with phosgene in the presence of an acid binder and a solvent. Examples of acid binders that can be used include alkali metal hydroxides such as pyridine, sodium hydroxide, and potassium hydroxide, and examples of solvents that can be used include methylene chloride and chloroform. To promote the condensation polymerization reaction, a tertiary amine catalyst such as triethylamine, or a quaternary ammonium salt such as benzyltriethylammonium chloride may be used.

[0022] In the above production method, it is preferable to further add to the reaction system a monofunctional compound such as phenol, p-tert-butylphenol (PTBP), p-cumylphenol, a long-chain alkyl-substituted phenol, an alkoxy-substituted phenol, or a benzotriazole-substituted phenol as a molecular weight regulator (end terminator). The timing of adding the molecular weight regulator (end terminator) is not particularly limited, and it may be added during or after the reaction of the dihydroxy compound.

[0023] The amount of the molecular weight modifier used is usually 0.95 moles or more, preferably 1.5 moles or more, and usually 10 moles or less, preferably 5 moles or less, per 100 moles of the dihydroxy compound.

[0024] The addition of a molecular weight modifier introduces a terminal structure derived from the molecular weight modifier to the terminal of the polycarbonate resin (copolymer). In one embodiment, the terminal structure derived from the molecular weight modifier is contained in an amount of typically 0.95 moles or more, preferably 1.5 moles or more, and typically 10 moles or less, preferably 5 moles or less, per 100 moles of structural units derived from dihydroxy compounds (i.e., the total of structural units (A) to (D) and structural units derived from other dihydroxy compounds). In one embodiment of the present invention, the terminal structure of the polycarbonate resin (copolymer) is derived from a compound selected from phenol, p-tert-butylphenol (PTBP), p-cumylphenol, long-chain alkyl-substituted phenols, alkoxy-substituted phenols, and benzotriazole-substituted phenols. The addition of a molecular weight modifier is advantageous in that it not only makes it possible to adjust the viscosity average molecular weight (Mv) of the polycarbonate resin to a desired range, but also imparts unique physical properties derived from the structure of the molecular weight modifier to the polycarbonate resin.

[0025] Examples of the alkoxy-substituted phenol include compounds represented by the following general formula (T1)'. By using the compound of the general formula (T1)' above, a terminal structure represented by the following general formula (T1) is introduced at the end of the main chain of the polycarbonate resin.

[0026] In formula (T1)′ and formula (T1), R Ａ represents an alkylene group having 1 to 20 carbon atoms or an alkenylene group having 2 to 20 carbon atoms, each of which may have a substituent; R Ｂ and R Ｃ each independently represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryl group having 6 to 12 carbon atoms; Z represents an ether bond, a carbonyl group, an ester bond, or a single bond; a represents an integer of 1 to 3; and * represents the bonding position with the main chain of the polycarbonate resin.

[0027] Examples of compounds represented by general formula (T1)' include, but are not limited to, p-hydroxyphenethyl alcohol (PHEP), m-hydroxyphenethyl alcohol, o-hydroxyphenethyl alcohol, o-hydroxybenzyl alcohol (i.e., salicyl alcohol), p-hydroxybenzyl alcohol, m-hydroxybenzyl alcohol, vanillyl alcohol, homovanillyl alcohol, 3-(4-hydroxy-3-methoxyphenyl)-1-propanol, sinapyl alcohol, coniferyl alcohol, and p-coumaryl alcohol. Among these, p-hydroxyphenethyl alcohol and p-hydroxybenzyl alcohol are preferred from the viewpoint of reactivity, and p-hydroxyphenethyl alcohol is more preferred. These alkoxy-substituted phenols are excellent in that they can introduce a hydroxyl group into the terminal of the main chain of the resulting polycarbonate resin, thereby imparting reactivity to the polycarbonate resin.

[0028] Alternatively, the molecular weight modifier may be a compound represented by the following general formula (T2)'. By using the compound of the above general formula (T2)', a terminal structure represented by the following general formula (T2) is introduced into the terminal of the main chain of the polycarbonate resin. In formula (T2)′ and formula (T2), R Ｄ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R Ｅ is an alkylene group having 1 to 6 carbon atoms, and R Ｆ is a hydrogen atom or a methyl group, and R Ｇ is a hydrogen atom or a halogen atom. * indicates the bonding position with the main chain of the polycarbonate resin.

[0029] Among these, the compound represented by the general formula (T2)' is preferably a compound represented by the following general formula (T3)'. By blending the compound represented by the general formula (T3)', a terminal structure represented by the following general formula (T3) is introduced at the end of the main chain of the polycarbonate resin. In formula (T3)′ and formula (T3), R Ｄrepresents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and * represents the bonding position with the main chain of the polycarbonate resin. These benzotriazole-substituted phenols are excellent in that they can impart to the resulting polycarbonate resin the reactivity derived from the methacrylic group and the ultraviolet absorption performance derived from the benzotriazole group.

[0030] In terms of reactivity during synthesis, availability, and cost, it is preferable to use, as the molecular weight modifier, a compound selected from the group consisting of p-t-butylphenol (PTBP), the compound represented by the above general formula (T1)′ (particularly, p-hydroxyphenethyl alcohol (PHEP)), and the compound represented by the above general formula (T2)′ (particularly, the compound represented by formula (T3)′).

[0031] In one embodiment of the present invention, the polycarbonate resin comprises a terminal structure selected from the terminal structure represented by the above general formula (T1) (particularly, a terminal structure derived from p-hydroxyphenethyl alcohol (PHEP)), the terminal structure represented by the above general formula (T2) (particularly, a terminal structure represented by the above general formula (T3)), and the terminal structure represented by the following formula (T4):

[0032] In one embodiment of the present invention, the polycarbonate resin comprises a terminal structure represented by the above formula (T4). The terminal structure represented by formula (T4) can be obtained, for example, by adding p-t-butylphenol (PTBP). In one embodiment of the present invention, the polycarbonate resin comprises a terminal structure represented by the above general formula (T1) (particularly, a terminal structure derived from p-hydroxyphenethyl alcohol (PHEP)). In one embodiment of the present invention, the polycarbonate resin comprises a terminal structure represented by the above general formula (T2) (particularly, a terminal structure represented by general formula (T3)).

[0033] If desired, small amounts of antioxidants such as sodium sulfite and hydrosulfite, and branching agents such as phloroglucin, isatin bisphenol and trisphenolethane may be added.

[0034] When producing a polycarbonate resin by the transesterification method or the melting method, a dihydroxy compound and a carbonate diester are typically reacted in the presence of a transesterification catalyst. Specific examples of carbonate diesters include aromatic carbonate diesters such as diphenyl carbonate, ditolyl carbonate, bis(2-chlorophenyl)carbonate, dinaphthyl carbonate, and bis(4-phenylphenyl)carbonate. At least one of an alkali metal compound and an alkaline earth metal compound can be used as the transesterification catalyst. A basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound can also be used as an auxiliary. One type of transesterification catalyst may be used, or multiple types may be used in combination.

[0035] [3] Physical Properties of Polycarbonate Resin The viscosity average molecular weight (Mv) of the polycarbonate resin according to the embodiment is preferably 10,000 to 80,000, more preferably 15,000 to 60,000, in terms of ease of handling of the resin solution, and is preferably 16,000 to 50,000, more preferably 18,000 to 32,000, in terms of processability of the resulting film.

[0036] The viscosity average molecular weight (Mv) of a polycarbonate resin can be measured by the following method: (Conditions for measuring viscosity average molecular weight (Mv)) Measuring instrument: Ubbelohde capillary viscometer Solvent: dichloromethane Resin solution concentration: 0.5 g / dL Measurement temperature: 25°C Measurement is performed under the above conditions, and the intrinsic viscosity [η] / dL is determined with a Huggins constant of 0.45, and then calculated using the following formula.

[0037] The glass transition temperature (Tg) of the polycarbonate resin is preferably 140 to 160°C, more preferably 143 to 160°C, and particularly preferably 145 to 155°C. Resins having a glass transition temperature within these ranges have excellent heat resistance. From the viewpoints of heat resistance and ease of molding, the glass transition temperature is preferably 145°C or higher, and more preferably 150°C or higher.

[0038] The glass transition temperature (Tg) of a polycarbonate resin can be measured by the following method. (Conditions for measuring glass transition temperature (Tg)) Measuring instrument: differential scanning calorimeter (DSC) Heating rate: 10°C / min Gas flow environment: nitrogen 20 ml / min Sample pretreatment: heating and melting at 300°C

[0039] As described above, the polycarbonate resin according to the embodiment has excellent solvent solubility. From the viewpoint of improving molding efficiency, it is preferable that the polycarbonate resin be dissolved at a concentration of 20% by mass or more relative to 100% by mass of the resin solution (the entire resin solution including the resin, solvent, additives, etc.). In particular, it is desirable that the polycarbonate resin be dissolved at a concentration of preferably 20% by mass or more, more preferably 25% by mass or more, relative to 100% by mass of the resin solution using a non-halogenated organic solvent (preferably at least one of a ketone solvent and an ester solvent, as described below) as the solvent.

[0040] [4] Polycarbonate resin composition Polycarbonate resin compositions may be prepared by adding additives such as antioxidants, processing stabilizers, light stabilizers, polymerized metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, mold release agents, UV absorbers, plasticizers, and compatibilizers to polycarbonate resins, as long as the properties of the resin are not impaired. The polycarbonate resin may be kneaded with one or more materials, such as polycarbonates other than the polycarbonate resin according to the embodiment, aromatic polyesters, aliphatic polyesters, polyamides, polystyrenes, polyolefins, acrylics, amorphous polyolefins, ABS, and AS, biodegradable resins such as polylactic acid and polybutylene succinate, and rubber, to form a polymer alloy.

[0041] The method for blending various additives into the polycarbonate resin is not particularly limited as long as it is a commonly used polymer blending method, and examples thereof include a method of mixing using a tumbler, V-type blender, super mixer, Nauta mixer, Banbury mixer, kneading roll, extruder, etc., or a solution blending method in which the above-mentioned components are mixed in a state of being dissolved in a common good solvent such as methylene chloride.

[0042] The polycarbonate resin or polycarbonate resin composition can be used as a raw material for various molded articles such as films, sheets, disks, lenses, and prisms.

[0043] [5] Molded Articles The polycarbonate resin according to the embodiment or a resin composition containing the same can be molded into a molded article. The method for molding the polycarbonate resin according to the embodiment or a resin composition containing the same is not particularly limited, and molding can be performed using various methods commonly used in the field. Examples include dry molding, such as compression molding, transfer molding, injection molding, blow molding, extrusion molding, laminate molding, and calendar molding; and wet molding, such as solution casting and casting. The polycarbonate resin according to the embodiment has excellent solvent solubility and dissolution stability, and can be successfully molded, particularly by wet molding. Any organic solvent capable of dissolving the polycarbonate resin according to the embodiment can be used as a solvent for wet molding. To efficiently wet-mold the resin, it is preferable to dissolve the resin in the organic solvent at a high concentration (e.g., 20% by mass or more relative to the solvent). The organic solvent can be selected from solvents commonly used in the field, but efficient wet molding can be achieved by using a solvent with a relatively low boiling point. Among these, non-halogenated organic solvents are preferred from the viewpoints of safety and health during wet molding and environmental protection. According to one embodiment of the present invention, there is provided a resin solution comprising a non-halogenated organic solvent and a polycarbonate resin dissolved in the non-halogenated organic solvent.

[0044] The non-halogenated organic solvent is not particularly limited, but from the viewpoint of improving the efficiency of wet molding, it is preferable to use one having a relatively low boiling point (for example, a boiling point of 100° C. or less, preferably 90° C. or less, more preferably 80° C. or less). Specific examples include ketone solvents, ester solvents, and ether solvents, with ketone solvents and ester solvents being preferred.

[0045] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone. Among these, methyl ethyl ketone is preferred due to its low boiling point and high solubility for polycarbonate resins. Examples of ester solvents include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, 2-ethoxyethyl acetate, 2-methoxy-1-methylethyl acetate, ethyl lactate, and ethyl carbitol acetate. Among these, ethyl acetate, ethyl carbitol acetate, and 2-methoxy-1-methylethyl acetate are preferred due to their low boiling point and high solubility for polycarbonate resins. In one embodiment, the non-halogen organic solvent is at least one of methyl ethyl ketone, ethyl acetate, ethyl carbitol acetate, and 2-methoxy-1-methylethyl acetate.

[0046] The resin concentration in the resin solution (100% by mass) is usually 1 to 50% by weight. From the viewpoint of improving the efficiency of wet molding, the concentration of the polycarbonate resin in the resin solution is preferably 20% by mass or more. The concentration of the polycarbonate resin in the resin solution is more preferably 25% by mass or more, for example, 20 to 50% by mass, 20 to 30% by mass, or 25 to 50% by mass. The polycarbonate resin according to the embodiment has a dissolved concentration of 20% by mass or more in at least one of a ketone solvent and an ester solvent in the resin solution (i.e., 20% by mass of the polycarbonate resin is contained in 100% by mass of the resin solution). In a preferred embodiment, the polycarbonate resin according to the embodiment has a dissolved concentration of 20% by mass or more in both a ketone solvent and an ester solvent in the resin solution.

[0047] As described above, the polycarbonate resin according to the embodiment can be efficiently formed into a molded article (e.g., a film-shaped molded article) by, for example, wet molding. Therefore, according to one embodiment of the present invention, a molded article obtained by wet molding a resin solution containing a polycarbonate resin, for example, a film produced (by wet molding) using a resin solution containing a polycarbonate resin, is provided. According to a further embodiment of the present invention, a method for producing a molded article (e.g., a film) is provided, which includes wet molding a resin solution containing a polycarbonate resin. The shape, pattern, color, dimensions, etc. of the molded article are not limited and can be determined as desired depending on the application. However, the polycarbonate resin according to the embodiment is particularly suitable as a film material for optical films and the like. Film formation by wet molding has the advantages of easily obtaining thin films and non-oriented films, as well as the advantage of producing high-quality films without discoloration or gel formation during high-temperature melting. Therefore, it is particularly used when forming films from materials with high glass transition temperatures.

[0048] Molded articles of polycarbonate resins according to the present invention can be used, for example, in electrical and electronic equipment, office automation equipment, optical media, automotive parts, and building materials. Specifically, they can be advantageously used in electrical and electronic devices (e.g., personal computers, game consoles, television receivers, display devices such as liquid crystal displays and plasma display devices, printers, copiers, scanners, fax machines, electronic organizers and PDAs, electronic desk calculators, electronic dictionaries, cameras, video cameras, mobile phones, smartphones, tablets, battery packs, recording medium drives and readers, mice, numeric keypads, CD players, MD players, portable radios and audio players, etc.). In particular, films produced by wet molding have excellent heat resistance and transparency, and are suitable for use as laminate films by laminating gas barrier films, solvent-resistant films, etc. on both sides of the film, or as liquid crystal display films such as liquid crystal substrate films (plastic cell substrates) or retardation films together with transparent conductive films and polarizing plates. These films can be advantageously used, specifically, in tablets, smartphones, handheld terminals, and various display elements. The plastic substrate is used unstretched, but in order to be used as a retardation film, it is stretched and oriented at least uniaxially to have optimal birefringence characteristics. As a method for stretching the film, known methods can be used, such as longitudinal uniaxial stretching, transverse uniaxial stretching, and multistage simultaneous biaxial stretching.

[0049] The present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited thereto. (Example 1) 54.0 g (0.237 mol) of bisphenol A (BPA) manufactured by Mitsubishi Chemical Corporation, 18.0 g (0.062 mol) of bisphenol AP (BPAP) manufactured by Honshu Chemical Industry Co., Ltd., 18.0 g (0.070 mol) of bisphenol C (BPC) manufactured by Honshu Chemical Industry Co., Ltd., and 0.5 g of hydrosulfite were dissolved in 500 ml of a 9% by mass aqueous sodium hydroxide solution and 300 ml of pure water. 300 ml of dichloromethane was added thereto, and while stirring, 51.1 g of phosgene was blown in over 40 minutes while maintaining the solution temperature in the range of 15 to 25°C.

[0050] After the phosgene injection was completed, 100 ml of a 9 wt / w % aqueous solution of sodium hydroxide, 200 ml of dichloromethane, and 2.13 g (0.0142 mol) of p-tert-butylphenol (PTBP) manufactured by Honshu Chemical Industry Co., Ltd. dissolved in 100 ml of dichloromethane were added and emulsified with vigorous stirring. Then, 0.5 ml of triethylamine (TEA) was added as a polymerization catalyst, and polymerization was carried out for about 40 minutes.

[0051] The polymerization solution was separated into an aqueous phase and an organic phase, and the organic phase was neutralized with phosphoric acid. The organic phase was then repeatedly washed with pure water until the pH of the washings became neutral. The organic solvent was evaporated from the polycarbonate resin solution thus prepared, yielding a powdered polycarbonate resin (PC-1). The resulting polycarbonate resin was a random copolymer composed of a BPA-derived structural unit (structural unit (A)), a BPAP-derived structural unit (structural unit (B)), and a BPC-derived structural unit (structural unit (C)), both of which had PTBP-derived structures.

[0052] Examples 2 to 12, Comparative Examples 1 to 8 Polycarbonate resins were produced in the same manner as in Example 1, except that the compounds shown in Table 1 were used as raw materials in the amounts shown.

[0053] Here, in Table 1, each numerical value (% by mass) means the proportion (% by mass) of the structural units derived from each compound when the total of the structural units derived from the compounds listed in Table 1 contained in the obtained resin is taken as 100% by mass. That is, when the total of the structural units derived from BPA, BPAP, and BPC contained in the resin is taken as 100% by mass, the resin of Example 1 contains 60% by mass of structural units derived from BPAP, 20% by mass of structural units derived from BPAP, and 20% by mass of structural units derived from BPC.

[0054] The physical properties of the resins obtained in the examples and comparative examples are shown in Table 2. Each physical property was measured by the following method. (1) Viscosity average molecular weight (Mv) <Conditions for measuring viscosity average molecular weight (Mv)> Measuring instrument: Ubbelohde capillary viscometer Solvent: dichloromethane Resin solution concentration: 0.5 g / dL Measurement temperature: 25°C Measurement was performed under the above conditions, and the intrinsic viscosity [η] / dL was determined with a Huggins constant of 0.45, and calculated using the following formula.

[0055] (2) Glass Transition Temperature (Tg) <Conditions for measuring glass transition temperature (Tg)> Measuring instrument: differential scanning calorimeter (DSC) (Shimadzu Corporation DSC-50) Heating rate: 10°C / min Gas flow environment: nitrogen 20 ml / min Sample pretreatment: heat melting at 300°C

[0056] (3) Solvent Solubility and Dissolution Stability The polycarbonate resins produced in the examples and comparative examples were mixed with a solvent at room temperature so that the concentration of the polycarbonate resin in the resin solution was 20% by mass (Examples 1 to 10, Comparative Examples 1 to 8), 25% by mass (Example 11), or 30% by mass (Example 12). Methyl ethyl ketone (MEK), ethyl acetate (AcOEt), ethyl carbitol acetate (ECA), or 2-methoxy-1-methylethyl acetate (PGMEA) was used as the solvent. Solvent solubility and dissolution stability were evaluated according to the following criteria: ">20 days": No cloudiness was observed for more than 20 days after complete dissolution. "up to 7 days": Cloudiness was observed within 4 to 7 days after complete dissolution. "up to 3 days": Cloudiness was observed within 2 to 3 days after complete dissolution. "up to 1 day": Cloudiness was observed within 1 day after complete dissolution. "Not dissolved": Not completely dissolved, and residual solvent was observed.

[0057] (4) Cost The cost of the polycarbonate resins produced in the Examples and Comparative Examples was examined. The cost evaluation in Table 2 is as follows: R1: Low to normal price (monomer cost less than 1,000 yen / kg) R2: Slightly expensive (monomer cost 1,000 to 1,500 yen / kg) H: Expensive (monomer cost more than 1,500 yen / kg)

[0058]

[0059] Table 2 shows that the resins of the examples have excellent solvent solubility and are relatively inexpensive. Furthermore, due to their relatively high glass transition temperatures, they also have excellent heat resistance. Conventionally, it has been difficult to dissolve polycarbonate resins with high glass transition temperatures at high concentrations in organic solvents with relatively low boiling points. Contrary to conventional wisdom, carbonate resins according to the embodiments can be dissolved at high concentrations in organic solvents with relatively low boiling points, even in environmentally friendly non-halogenated solvents. By utilizing these properties, polycarbonate resins according to the embodiments can be efficiently molded by wet molding. Furthermore, the polycarbonate resins according to the embodiments have excellent dissolution stability and can be stably stored for long periods in the form of a resin solution in which the resin is dissolved in a solvent. On the other hand, the resins of the comparative examples have poor solvent solubility and / or dissolution stability. Because the resin solution cannot be stably stored for long periods, it is necessary to shorten the resin solution preparation cycle and to check for cloudiness (resin precipitation) each time the resin solution is used. In particular, in the case of a resin solution that becomes cloudy within one day of preparation, it must be used immediately after preparation, which means that the resin solution must be prepared every time it is used, which is not preferable from the viewpoint of practicality.

[0060] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

Claims

1. It comprises a monomer-derived constituent unit (A) represented by the following formula (1), a monomer-derived constituent unit (B) represented by the following formula (2), a monomer-derived constituent unit (C) represented by the following formula (3), and / or a monomer-derived constituent unit (D) represented by the following formula (4), A polycarbonate resin in which, with respect to the total of the constituent units (A), (B), (C), and (D) constituting the resin, the proportion of constituent unit (A) is 50 to 65% by mass, the proportion of constituent unit (B) is 10 to 30% by mass, and the total proportion of constituent units (C) and (D) is 5 to 30% by mass. 【Chemistry 1】

2. The polycarbonate resin according to claim 1, comprising a monomer-derived structural unit (A) represented by formula (1), a monomer-derived structural unit (B) represented by formula (2), and a monomer-derived structural unit (C) represented by formula (3).

3. The polycarbonate resin according to claim 1, comprising a monomer-derived structural unit (A) represented by formula (1), a monomer-derived structural unit (B) represented by formula (2), and a monomer-derived structural unit (D) represented by formula (4).

4. The polycarbonate resin according to claim 1, comprising a monomer-derived structural unit (A) represented by formula (1), a monomer-derived structural unit (B) represented by formula (2), a monomer-derived structural unit (C) represented by formula (3), and a monomer-derived structural unit (D) represented by formula (4).

5. The polycarbonate resin according to claim 1, wherein the viscosity-average molecular weight (Mv) is 10,000 to 80,000.

6. The polycarbonate resin according to claim 1, wherein the glass transition temperature (Tg) is 140 to 160°C.

7. A resin solution comprising a non-halogenated organic solvent and the polycarbonate resin according to claim 1 dissolved in the non-halogenated organic solvent.

8. The resin solution according to claim 7, wherein the polycarbonate resin is contained in the resin solution in an amount of 20% by mass or more.

9. The resin solution according to claim 7, wherein the non-halogenated organic solvent is at least one of a ketone solvent and an ester solvent.

10. A film made using the resin solution described in any one of claims 7 to 9.

11. A method for producing a film, comprising wet molding the resin solution described in any one of claims 7 to 9.

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