JP7658149B2 - Polycarbonate resin and molded products - Google Patents

Description

The present invention relates to polycarbonate resins and molded articles that have excellent mechanical strength and heat resistance.

Polycarbonate resins generally contain bisphenols as monomer components, and taking advantage of their advantages such as transparency, heat resistance, and mechanical strength, they are widely used as so-called engineering plastics in the optical field, such as electric and electronic parts, automotive parts, optical recording media, and lenses.
On the other hand, due to concerns about global warming caused by the depletion of petroleum resources and the increase in carbon dioxide emissions, there is a demand for the development of plastics made from carbon-neutral plant-derived monomers. In this context, polycarbonate resins produced using isosorbide (hereinafter sometimes referred to as "ISB"), a plant-derived raw material, have been developed in recent years and have begun to be used for automobile parts, optical applications, and glass replacement applications (see, for example, Patent Documents 1 and 2).

Polycarbonate resins obtained from ISB not only have excellent optical properties, but also have extremely excellent weather resistance and surface hardness compared to conventional aromatic polycarbonate resins. On the other hand, there is a demand for further improvement in mechanical properties such as tensile elongation and impact resistance in areas where stress is concentrated.
To address this issue, for example, Patent Document 3 discloses a method for improving impact resistance by incorporating an elastomer into a polycarbonate resin.

International Publication No. 2004/111106 International Publication No. 2007/148604 JP 2017-88774 A

As disclosed in Patent Document 3, by blending an elastomer with a polycarbonate resin, excellent improvement in impact resistance can be expected, but in many cases, the materials used as impact improvers are derived from petroleum and other mainly exhaustible resources. In recent years, as the use of non-exhaustible resources is increasingly expected, there is a demand from society for resins that have a higher biomass content and excellent practical properties.
An object of the present invention is to provide a polycarbonate resin which has a higher biomass content and is excellent in mechanical strength and heat resistance.

As a result of intensive research aimed at solving the above problems, the inventors have found that by using a specific compound as a copolymerization component, a polycarbonate resin having excellent mechanical strength and heat resistance can be obtained. That is, the gist of the present invention is as follows.

That is, the present invention relates to the following.
[1] A polycarbonate resin containing at least a structural unit (A) represented by the following formula (1), a structural unit (B) represented by the following formula (2), and a structural unit (C) derived from an aliphatic dihydroxy compound and/or an alicyclic dihydroxy compound, the polycarbonate resin containing 40% by weight or more and 80% by weight or less of the structural unit (A) and 1% by weight or more and 20% by weight or less of the structural unit (B), and the number average molecular weight of the structural unit (B) is 1,200 or more and 5,000 or less.

In formula (2), n is an integer of 2 or more.
[2] The polycarbonate resin according to [1], containing 1% by weight or more and 40% by weight or less of the structural unit (C).
[3] The polycarbonate resin according to [1] or [2], containing, as the structural unit (C), 1 wt % or more and 40 wt % or less of a structural unit represented by the following formula (3):

[4] The polycarbonate resin according to any one of [1] to [3], having a glass transition temperature of 90° C. or higher and 140° C. or lower.
[5] A molded article obtained by molding the polycarbonate resin according to any one of [1] to [4].
[6] A method for producing the polycarbonate resin according to any one of [1] to [4], comprising a step of polycondensing raw materials including at least a dihydroxy compound forming the structural unit (A) represented by formula (1), a dihydroxy compound forming the structural unit (B) represented by formula (2), a dihydroxy compound forming the structural unit (C), and a monomer containing a diester carbonate by transesterification, in which the dihydroxy compound forming the structural unit (B) represented by formula (2) is polytrimethylene ether glycol, and the number average molecular weight of this polytrimethylene ether glycol is 1,200 or more and 5,000 or less.

The polycarbonate resin of the present invention has excellent mechanical strength and heat resistance, and by using such a polycarbonate resin, it is possible to obtain high-quality molded products. In addition, the polycarbonate resin of the present invention has a high biomass content, and can contribute to the realization of a sustainable society.

The present invention will be described in detail below, but the present invention is not limited to the following description, and can be modified in any manner without departing from the gist of the present invention.
In this specification, when an expression is used using "~" followed by a numerical value or physical property value, the values before and after the expression are used as including the values before and after the expression.

In this specification, the term "repeated structural unit" refers to a structural unit in which the same structure appears repeatedly in a resin, and each of the structural units is linked to form the resin. For example, in the case of a polycarbonate resin, the carbonyl group is also referred to as the repeating structural unit. In addition, the term "structural unit" refers to a partial structure that constitutes a resin, and a specific partial structure contained in the repeating structural unit. For example, it refers to a partial structure sandwiched between adjacent linking groups in a resin, or a partial structure sandwiched between a polymerizable reactive group present at the end of a polymer and a linking group adjacent to the polymerizable reactive group. More specifically, in the case of a polycarbonate resin, a carbonyl group is a linking group, and a partial structure sandwiched between adjacent carbonyl groups is referred to as a structural unit.
In this specification, the weight ratio of each structural unit in the polycarbonate resin is calculated assuming that the total weight of all structural units and linking groups is 100% by weight.

[Polycarbonate resin]
The polycarbonate resin of the present invention is a polycarbonate resin containing at least a structural unit (A) represented by the following formula (1) (hereinafter may be simply referred to as structural unit (A)), a structural unit (B) represented by the following formula (2) (hereinafter may be simply referred to as structural unit (B)), and a structural unit (C) derived from an aliphatic dihydroxy compound and/or an alicyclic dihydroxy compound (hereinafter may be simply referred to as structural unit (C)).
The structural unit (A) is contained in an amount of 40% by weight or more and 80% by weight or less, and the structural unit (B) is contained in an amount of 1% by weight or more and 20% by weight or less, and the number average molecular weight of the structural unit (B) is 1,200 or more and 5,000 or less.

In formula (2), n is an integer of 2 or more.

Dihydroxy compounds forming the structural unit (A) include isosorbide (ISB), isomannide, and isoidet, which are stereoisomers. These may be used alone or in combination of two or more. Among them, isosorbide obtained by dehydration condensation of sorbitol, which is produced from various starches that are abundant and easily available as a plant-derived resource, is particularly preferred in terms of availability, ease of production, and properties of the resulting molded products (e.g., heat resistance, impact resistance, surface hardness).

The weight ratio of the structural unit (A) in the polycarbonate resin of the present invention is 40% by weight or more and 80% by weight or less, and the lower limit is particularly preferably 45% by weight or more. The upper limit is more preferably 75% by weight or less, even more preferably 70% by weight or less, and particularly preferably 65% by weight or less. Within the above range, a resin with an excellent balance of mechanical strength, heat resistance, and melt processability can be obtained.

As the dihydroxy compound forming the structural unit (B), polytrimethylene ether glycol (PO3G) is used. It is preferable to use PO3G having a biomass degree of 100%, which is synthesized by condensing 1,3-propanediol produced from plant-derived raw materials. Whether isosorbide or PO3G is produced from plant-derived resources can be confirmed, for example, by measuring the concentration of radioactive carbon ( ¹⁴ C).

PO3G having a number average molecular weight of 1200 or more and 5000 or less is used. The lower limit is more preferably 1500 or more, and particularly preferably 1700 or more. The upper limit is more preferably 4000 or less, and particularly preferably 3000 or less. When the number average molecular weight of PO3G is within the above range, the structural unit (B) that becomes the soft segment forms a microphase separation structure in the resin, and further has a moderate compatibility with the structural unit (A), so that adhesion at the phase interface is obtained and excellent impact resistance can be expressed. In addition, the average value (average polymerization degree) of n of the structural unit (B) in the polycarbonate resin is preferably 20 or more and 90 or less. The lower limit is more preferably 25 or more, and particularly preferably 30 or more. The upper limit is more preferably 70 or less, and particularly preferably 55 or less. The number average molecular weight and average polymerization degree of PO3G are calculated from the analysis of the hydroxyl value described later.

The weight ratio of the structural unit (B) in the polycarbonate resin of the present invention is 1% by weight or more and 20% by weight or less. The lower limit is more preferably 2% by weight or more, and particularly preferably 3% by weight or more. The upper limit is more preferably 15% by weight or less, and particularly preferably 12% by weight or less. Within the above range, a resin with an excellent balance between impact resistance and heat resistance can be obtained.

The characteristics of PO3G are explained by comparing it with polyethylene glycol (PEG), polypropylene glycol (PPG), and polytetramethylene ether glycol (PTMG), which are compounds similar to PO3G. PEG has good compatibility with the structural unit (A), so it does not form a phase-separated structure, and its performance, such as impact resistance, is inferior to PO3G. PO3G has moderate compatibility with the structural unit (A), and forms a form in which the phase consisting of the PO3G structural unit is uniformly dispersed in micron size, and it exhibits excellent impact resistance. PPG, like PEG, also has high compatibility with the structural unit (A), and is difficult to form a phase-separated structure. In addition, PPG has the disadvantage of having a relatively low thermal decomposition temperature, and has poor thermal stability. PTMG has low compatibility with the structural unit (A), and causes macroscopic phase separation, so high impact resistance cannot be obtained.

The polycarbonate resin of the present invention further contains a structural unit (C) derived from an aliphatic dihydroxy compound and/or an alicyclic dihydroxy compound. The polycarbonate resin of the present invention may simultaneously have a structural unit derived from an aliphatic dihydroxy compound and a structural unit derived from an alicyclic dihydroxy compound, in which case both structural units are collectively referred to as "structural unit (C)."

Examples of aliphatic dihydroxy compounds include the following dihydroxy compounds: linear aliphatic dihydroxy compounds such as ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-heptanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol; branched aliphatic dihydroxy compounds such as 1,3-butanediol, 1,2-butanediol, neopentyl glycol, and hexylene glycol.

Examples of alicyclic dihydroxy compounds include the following dihydroxy compounds: Dihydroxy compounds that are primary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, pentacyclopentadecane dimethanol, 2,6-decalin dimethanol, 1,5-decalin dimethanol, 2,3-decalin dimethanol, 2,3-norbornane dimethanol, 2,5-norbornane dimethanol, 1,3-adamantanedimethanol, and dihydroxy compounds derived from terpene compounds such as limonene; Dihydroxy compounds that are secondary or tertiary alcohols of alicyclic hydrocarbons, such as 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,3-adamantanediol, hydrogenated bisphenol A, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.

Among the above aliphatic dihydroxy compounds or alicyclic dihydroxy compounds, alicyclic dihydroxy compounds are more preferred from the viewpoint of excellent balance between mechanical properties and heat resistance, with 1,4-cyclohexanedimethanol and tricyclodecane dimethanol being even more preferred, and 1,4-cyclohexanedimethanol being particularly preferred.

The polycarbonate resin of the present invention preferably contains 1% by weight or more and 40% by weight or less of structural units (C) derived from an aliphatic dihydroxy compound or an alicyclic dihydroxy compound. The lower limit is more preferably 5% by weight or more, even more preferably 10% by weight or more, and particularly preferably 15% by weight or more. The upper limit is more preferably 35% by weight or less, and particularly preferably 30% by weight or less. Within the above range, a resin with an excellent balance between impact resistance and heat resistance can be obtained.

It is particularly preferable that the polycarbonate resin of the present invention contains 1% by weight or more and 40% by weight or less of the structural unit represented by the following formula (3) as the structural unit (C). In this case, the resin can have an even better balance between impact resistance and heat resistance.

The polycarbonate resin of the present invention may contain structural units other than the structural units (A), (B), and (C) (hereinafter, these may be referred to as "other structural units"). Examples of compounds that form other structural units include ether-containing dihydroxy compounds, acetal-containing dihydroxy compounds, aromatic-containing dihydroxy compounds, and diester compounds. A polycarbonate resin that partially incorporates structural units derived from a diester compound is called a polyester carbonate resin. In this specification, polycarbonate resin includes polyester carbonate resin.

As the ether-containing dihydroxy compound, for example, oxyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol can be used.

Examples of the acetal-containing dihydroxy compound that can be used include spiroglycol (also known as 3,9-bis(1,1-dimethyl-2-hydroxyethyl-2,4,8,10-tetraoxaspiro[5,5]undecane) and dioxane glycol (also known as 2-(1,1-dimethyl-2-hydroxyethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane).

Examples of the aromatic dihydroxy compound include the following compounds: 2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-diethylphenyl)propane, 2,2-bis(4-hydroxy-(3-phenyl)phenyl)propane, 2,2-bis(4-hydroxy-(3,5-diphenyl)phenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,1-bis(4-hydroxyphenyl) phenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)decane, bis(4-hydroxy-3-nitrophenyl)methane, 3,3-bis(4-hydroxyphenyl)pentane, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 1,3-bis(2-(4-hydroxyphenyl)-2-propyl)benzene, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)sulfone, 2,4'-dihydroxydiphenyl sulfone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxyphenyl)disulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dichlorodiphenyl ether aromatic bisphenol compounds such as 2,2-bis(4-(2-hydroxyethoxy)phenyl)propane, 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane, 1,3-bis(2-hydroxyethoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, and bis(4-(2-hydroxyethoxy)phenyl)sulfone; dihydroxy compounds having an ether group bonded to an aromatic group such as 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxypropoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, and 9,9-bis(4-(2-hydroxypropoxy)-3-methylphenyl)fluorene. dihydroxy compounds having a fluorene ring, such as 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, and 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene.

Examples of the diester compound include the following compounds: aromatic dicarboxylic acids such as terephthalic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. These dicarboxylic acid components can be used as raw materials for polyester carbonate resins as dicarboxylic acids themselves, but depending on the production method, dicarboxylic acid esters such as methyl esters and phenyl esters, and dicarboxylic acid derivatives such as dicarboxylic acid halides can also be used as raw materials.

By using aromatic dihydroxy compounds or diester compounds such as bisphenol compounds as copolymerization components, the heat resistance of polycarbonate resins can be improved in some cases, but on the other hand, if the polycarbonate resin contains a large amount of aromatic structures, the weather resistance tends to decrease. In addition, since there is a large difference in the polymerization reactivity between bisphenol compounds or diester compounds and dihydroxy compounds that form structural units (A) or (B), the bisphenol compounds or diester compounds remain unreacted or remain in the terminal groups, making it difficult to obtain polycarbonate resins with high molecular weights, and mechanical properties such as impact resistance tend to decrease. If the reaction temperature is raised to promote the reaction, the structural unit (A) will thermally decompose, and the resulting polycarbonate resin will tend to become colored. For these reasons, the content of structural units derived from aromatic dihydroxy compounds or diester compounds is preferably 15% by weight or less, more preferably 10% by weight or less, and particularly preferably 5% by weight or less.

(carbonic acid diester)
The linking group of the above structural unit contained in the polycarbonate resin of the present invention is introduced by polymerizing a carbonate diester represented by the following formula (4).

(In formula (4), R ¹ and R ² are each an aliphatic hydrocarbon group having 1 to 18 carbon atoms which may have a substituent, or an aromatic hydrocarbon group which may have a substituent, and R ¹ and R ² may be the same or different.)

^R1 and ^R2 are preferably substituted or unsubstituted aromatic hydrocarbon groups, more preferably unsubstituted aromatic hydrocarbon groups. Examples of the substituents of the aliphatic hydrocarbon groups include ester groups, ether groups, amide groups, and halogen atoms, and examples of the substituents of the aromatic hydrocarbon groups include alkyl groups such as methyl groups and ethyl groups.

Examples of the carbonic acid diester represented by the formula (4) include diphenyl carbonate (hereinafter sometimes abbreviated as "DPC"), substituted diphenyl carbonate such as ditolyl carbonate, and dialkyl carbonate such as dimethyl carbonate, diethyl carbonate, and di-tert-butyl carbonate, with diphenyl carbonate and substituted diphenyl carbonate being preferred, and diphenyl carbonate (DPC) being particularly preferred.

Carbonate diesters may contain impurities such as chloride ions, which may inhibit the polymerization reaction or deteriorate the hue of the resulting resin, so it is preferable to use distilled or other purified products as necessary.

[Production method of polycarbonate resin]
The polycarbonate resin of the present invention can be synthesized by a process of polycondensation reaction by transesterification using as raw materials at least a dihydroxy compound forming the structural unit (A) represented by the formula (1), a dihydroxy compound forming the structural unit (B) represented by the formula (2), a dihydroxy compound forming the structural unit (C), and a monomer containing a diester carbonate. More specifically, the polycarbonate resin can be obtained by removing, from the system, a monohydroxy compound and the like that are by-produced in the transesterification reaction during polycondensation.

In this step, specific examples of the dihydroxy compound forming the structural unit (A), the dihydroxy compound forming the structural unit (B), and the dihydroxy compound forming the structural unit (C) are the same as those described above. In particular, it is preferable that the dihydroxy compound forming the structural unit (B) is polytrimethylene ether glycol (PO3G), and the number average molecular weight of the polytrimethylene ether glycol is 1200 or more and 5000 or less. The lower limit is more preferably 1500 or more, and particularly preferably 1700 or more. The upper limit is more preferably 4000 or less, and particularly preferably 3000 or less. When the number average molecular weight of PO3G is within the above range, the structural unit (B) that becomes the soft segment forms a microphase separation structure in the resin, and further, since it has a moderate compatibility with the structural unit (A), adhesion at the phase interface is obtained, and excellent impact resistance can be expressed. The number average molecular weight of PO3G is calculated from the analysis of the hydroxyl value described later.

The transesterification reaction proceeds in the presence of a transesterification reaction catalyst (hereinafter referred to as a "polymerization catalyst"). The type of polymerization catalyst can have a significant effect on the reaction rate of the transesterification reaction and the quality of the resulting polycarbonate resin.

There are no particular limitations on the polymerization catalyst, so long as it satisfies the transparency, color tone, heat resistance, weather resistance, and mechanical properties of the resulting polycarbonate resin. For example, metal compounds of Group 1 or Group 2 (hereinafter simply referred to as "Group 1" and "Group 2") in the long-form periodic table, as well as basic compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds, can be used as the polymerization catalyst, and among these, Group 1 metal compounds and/or Group 2 metal compounds are preferred.

Examples of the Group 1 metal compounds include the following compounds: sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, cesium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, sodium acetate, potassium acetate, lithium acetate, cesium acetate, sodium stearate, potassium stearate, lithium stearate, cesium stearate, sodium borohydride, potassium borohydride, lithium borohydride, cesium borohydride, sodium phenylborohydride, boron phenylide Potassium, lithium phenyl boron, cesium phenyl boron, sodium benzoate, potassium benzoate, lithium benzoate, cesium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, dicesium hydrogen phosphate, disodium phenylphosphate, dipotassium phenylphosphate, dilithium phenylphosphate, dicesium phenylphosphate, sodium, potassium, lithium, cesium alcoholates, phenolates, disodium salts, dipotassium salts, dilithium salts, and dicesium salts of bisphenol A, etc. As the Group 1 metal compound, lithium compounds are preferred from the viewpoints of polymerization activity and the color tone of the resulting polycarbonate resin.

Examples of the Group 2 metal compounds include the following compounds: calcium hydroxide, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate, calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate, and strontium stearate. As the Group 2 metal compound, a magnesium compound, a calcium compound, or a barium compound is preferred, and from the viewpoint of polymerization activity and the color tone of the resulting polycarbonate resin, a magnesium compound and/or a calcium compound is more preferred, and a calcium compound is most preferred.

It is possible to use a basic compound such as a basic boron compound, a basic phosphorus compound, a basic ammonium compound, or an amine compound in combination with the Group 1 metal compound and/or the Group 2 metal compound as an auxiliary, but it is more preferable to use only the Group 1 metal compound and/or the Group 2 metal compound. From the viewpoint of the color tone of the obtained polycarbonate resin, it is most preferable to use only the Group 2 metal compound.

The lower limit of the amount of the polymerization catalyst used is preferably 0.1 μmol or more per mol of all dihydroxy compounds used in the reaction, more preferably 0.5 μmol or more, and particularly preferably 1 μmol or more. The upper limit of the amount of the polymerization catalyst used is preferably 300 μmol or less per mol of all dihydroxy compounds used in the reaction, more preferably 100 μmol or less, and particularly preferably 50 μmol or less.

By adjusting the amount of polymerization catalyst used within the above range, the polymerization rate can be increased, making it possible to obtain a polycarbonate resin of the desired molecular weight without necessarily increasing the polymerization temperature, and thus preventing the color tone of the polycarbonate resin from deteriorating. In addition, it is possible to prevent unreacted raw materials from volatilizing during the polymerization, which would cause the molar ratio of the dihydroxy compound and the carbonic acid diester to be lost, so that a resin of the desired molecular weight and copolymerization ratio can be obtained more reliably. Furthermore, it is possible to prevent the occurrence of side reactions at the same time, which further prevents the color tone of the polycarbonate resin from deteriorating or discoloring during molding.

Considering the adverse effect of sodium, potassium, and cesium among group 1 metals on the color tone of polycarbonate resin, and the adverse effect of iron on the color tone of polycarbonate resin, the total content of sodium, potassium, cesium, and iron in polycarbonate resin is preferably 1 weight ppm or less. In this case, the deterioration of the color tone of polycarbonate resin can be further prevented, and the color tone of polycarbonate resin can be further improved. From the same viewpoint, the total content of sodium, potassium, cesium, and iron in polycarbonate resin is more preferably 0.5 weight ppm or less.
These metals may be mixed in not only from the catalyst used but also from the raw materials or reaction equipment. Regardless of the source, the total amount of these metal compounds in the polycarbonate resin is preferably within the above-mentioned range as the total content of sodium, potassium, cesium and iron.

The method of polycondensing a dihydroxy compound and a carbonic acid diester is carried out in multiple stages using multiple reactors in the presence of the above-mentioned catalyst. The reaction may be carried out in a batch manner, a continuous manner, or a combination of a batch manner and a continuous manner. It is preferable to use a continuous manner, which is excellent in productivity and can produce polycarbonate resin with less thermal history.

From the viewpoint of controlling the polymerization rate and the quality of the resulting polycarbonate resin, it is important to appropriately select the jacket temperature, internal temperature, and pressure in the reaction system according to the reaction stage. Specifically, it is preferable to obtain a prepolymer at a relatively low temperature and low vacuum in the early stage of the polycondensation reaction, and to increase the molecular weight to a predetermined value at a relatively high temperature and high vacuum in the later stage of the reaction. In this case, the distillation of unreacted monomers is suppressed, and it becomes easier to adjust the molar ratio of the dihydroxy compound and the carbonate diester to the desired ratio. As a result, the decrease in the polymerization rate can be suppressed. In addition, it becomes possible to more reliably obtain a polymer with the desired molecular weight and terminal groups.

By adjusting the temperature of the polycondensation reaction, it is possible to improve productivity and avoid an increase in the heat history of the product. Furthermore, it is possible to further prevent the volatilization of the monomer and the decomposition and coloration of the polycarbonate resin. Specifically, the following conditions can be adopted as the reaction conditions in the first stage reaction. That is, the maximum temperature inside the polymerization reactor is usually set in the range of 160 to 230°C, preferably 180 to 220°C, and more preferably 190 to 215°C. In addition, the pressure of the polymerization reactor (hereinafter, pressure refers to absolute pressure) is usually set in the range of 1 to 110 kPa, preferably 5 to 50 kPa, and more preferably 7 to 30 kPa. In addition, the reaction time is usually set in the range of 0.1 to 10 hours, preferably 1 to 5 hours. It is preferable that the first stage reaction is carried out while distilling off the generated monohydroxy compound outside the reaction system.

From the second stage onwards, it is preferable to gradually reduce the pressure of the reaction system from the pressure of the first stage, and ultimately reduce the pressure (absolute pressure) of the reaction system to 1 kPa or less while removing the monohydroxy compound that is subsequently generated from the reaction system. The maximum internal temperature of the polymerization reactor is usually set in the range of 200 to 260°C, preferably 210 to 240°C, and particularly preferably 215 to 235°C. The reaction time is usually set in the range of 0.1 to 10 hours, preferably 0.5 to 5 hours, and particularly preferably 1 to 3 hours.

Once it is confirmed that the specified melt viscosity (molecular weight) has been reached using the stirring power as an indicator, the polymerization reaction is stopped by either introducing nitrogen into the reactor to return the pressure to normal pressure, or by withdrawing the molten resin from the reactor. The molten resin is discharged from the die head in the form of strands, cooled and solidified, and pelletized using a rotary cutter or similar. If necessary, extrusion devolatilization, extrusion kneading, and extrusion filtration processes may be added before pelletization. In these processes, additives are mixed into the resin, low molecular weight components are devolatilized using a vacuum vent, and foreign matter is removed using a polymer filter.

[Additives]
Examples of additives that can be used within the range not impairing the effects of the present invention include antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, fillers and other fillers, neutralizing agents, lubricants, antifogging agents, antiblocking agents, slip agents, dispersants, colorants, flame retardants, antistatic agents, conductivity imparting agents, crosslinking agents, crosslinking assistants, metal deactivators, molecular weight regulators, antibacterial agents, antifungal materials, fluorescent brightening agents, and light diffusing agents such as organic diffusing agents and inorganic diffusing agents. These additives can be used within the range not impairing the effects of the present invention.

[Characteristics of polycarbonate resin]
Biomass degree The biomass degree of a polycarbonate resin is defined as the weight ratio of structural units synthesized from plant-derived resources among all structural units constituting the polycarbonate resin. The polycarbonate resin of the present invention preferably has a biomass degree of 55% by weight or more, particularly preferably 60% by weight or more. In the examples described below, ISB and PO3G are synthesized from plant-derived resources, and the other CHDM and DPC are synthesized from fossil resources, so the biomass degree of a polycarbonate resin synthesized using these is the sum of the weight ratios of the structural units derived from ISB and the structural units derived from PO3G.

Melt Viscosity The melt viscosity of the polycarbonate resin of the present invention is preferably 1000 Pa·s or more and 8000 Pa·s or less. The lower limit is more preferably 1500 Pa·s or more, and particularly preferably 2000 Pa·s or more. The upper limit is more preferably 6000 Pa·s or less, and particularly preferably 4000 Pa·s or less. Within the above range, a resin with an excellent balance between mechanical properties and fluidity can be obtained. In this specification, the melt viscosity refers to the melt viscosity measured using a capillary rheometer [manufactured by Toyo Seiki Seisakusho] at a temperature of 220°C and a shear rate of 91.2 sec ^-1 . The method for measuring the melt viscosity will be described in detail later.

Glass transition temperature The glass transition temperature of the polycarbonate resin of the present invention is preferably 90°C or higher and 140°C or lower. The lower limit is more preferably 100°C or higher, and particularly preferably 110°C or higher. The upper limit is more preferably 135°C or lower, and particularly preferably 130°C or lower. Within the above range, it is applicable to a wide range of applications, is easy to melt process, and is easy to balance mechanical properties such as impact resistance. The details of the method for measuring the glass transition temperature will be described later. The glass transition temperature of the polycarbonate resin can be appropriately adjusted, for example, by selecting the weight ratio of the structural unit (A), structural unit (B), and structural unit (C) or the type of monomer into which each structural unit is introduced.

Impact Strength The polycarbonate resin of the present invention preferably has an Izod impact value of 20 kJ/ ^m2 or more, particularly preferably 25 kJ/ ^m2 or more, as measured by the method described below. If the Izod impact value is within the above range, the resin has sufficiently high impact strength, and can be used for applications such as automobile interior parts that require high impact resistance, and for molded products having fitting parts that are prone to breakage due to stress concentration.

[Polycarbonate resin composition]
The polycarbonate resin of the present invention can be kneaded with one or more of the following resins, for example: polycarbonate, aromatic polyester, aliphatic polyester, polyamide, polystyrene, polyolefin, amorphous polyolefin, acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), and other synthetic resins; elastomers such as acrylic rubber and butadiene rubber; and biodegradable resins such as polylactic acid and polybutylene succinate, within a range that does not impair the effects of the present invention. Of these, from the viewpoint of excellent impact resistance and transparency of the resin composition, it is preferable to contain an acrylic rubber, and more preferably to contain an acrylic rubber having a core-shell structure. Of these, alkyl acrylate-alkyl methacrylate-styrene copolymers are particularly preferable.

[Method of producing resin composition]
The resin composition can be produced, for example, by a method of mechanically melt-kneading each of the above-mentioned components constituting the resin composition. As the melt kneader, for example, a single screw extruder, a twin screw extruder, a Brabender, a Banbury mixer, a kneader blender, a roll mill, etc. can be used. In kneading, each component may be kneaded at once, or a multi-stage division kneading method in which an arbitrary component is kneaded and then the remaining components are added and kneaded may be used. Among them, a method in which each component is continuously charged using a twin screw extruder equipped with a vacuum vent and a resin composition is continuously obtained is preferable from the viewpoint of productivity and quality uniformity. The lower limit of the kneading temperature is usually 150 ° C or more, preferably 180 ° C or more, more preferably 200 ° C or more. The upper limit of the kneading temperature is usually 280 ° C or less, preferably 260 ° C or less, more preferably 250 ° C or less, and particularly preferably 240 ° C or less. In this range, productivity (processing speed of kneading) can be increased while suppressing heat deterioration due to heating by the kneader and heat generation by shear.

[Method of manufacturing molded products]
The polycarbonate resin of the present invention can be processed into various molded products by molding methods such as injection molding (insert molding, two-color molding, sandwich molding, gas injection molding, etc.), extrusion molding, inflation molding, T-die film molding, lamination molding, blow molding, hollow molding, compression molding, and calendar molding. The shape of the molded product is not particularly limited, and examples thereof include sheets, films, plates, particles, lumps, fibers, rods, porous bodies, and foams, and are preferably sheets, films, and plates. The molded film can also be uniaxially or biaxially stretched. Examples of stretching methods include roll method, tenter method, and tubular method. Furthermore, surface treatments such as corona discharge treatment, flame treatment, plasma treatment, and ozone treatment, which are usually used industrially, can also be performed.

[Application]
The uses are not particularly limited, but since the polycarbonate resin of the present invention has excellent weather resistance in addition to mechanical strength, it is particularly suitable for use in interior and exterior components of automobiles, building materials used outdoors (lighting covers, carports, highway soundproofing walls, etc.), housings for electric and electronic devices, and containers for food, cosmetics, etc.

The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.

[Measurement method]
Various physical properties were measured according to the following methods.

Number average molecular weight and average degree of polymerization (n) of polytrimethylene ether glycol (PO3G)
The hydroxyl value of polytrimethylene ether glycol was measured by a method using an acetylation reagent in accordance with JIS K1557-1. The number average molecular weight and average degree of polymerization (n) were calculated from the hydroxyl value using the following formula.
Number average molecular weight=1/(hydroxyl value/1000/56.11/2)
Hydroxyl value unit: mg-KOH/g-polymer
56.11: Molecular weight of calcium hydroxide (KOH) Average degree of polymerization = (number average molecular weight - 1.0 x 2 - 16.0) / 58.1
1.0: molecular weight of hydrogen atom 16.0: molecular weight of oxygen atom 58.1: molecular weight of repeating unit (C ₃ H ₆ O) of polytrimethylene ether glycol

Biomass Degree The sum of the weight ratios of the structural units derived from ISB and the structural units derived from PO3G represents the biomass degree of the polycarbonate resin.

Melt Viscosity The pellet-shaped resin was vacuum dried at 100°C for 5 hours or more. The melt viscosity of the pellet was then measured using a capillary rheometer (manufactured by Toyo Seiki Co., Ltd.). An orifice of 1 mmφ×10 mmL was used, the temperature was set to 220°C, and the measurement was performed at a shear rate of 6.08 to 1824 sec ^-1 . The value at a shear rate of 91.2 ^sec-1 was taken as the melt viscosity of the resin to be measured.

Glass transition temperature The glass transition temperature was measured using a differential scanning calorimeter DSC6220 (manufactured by SII Nanotechnology Co., Ltd.). Approximately 10 mg of the resin was placed in an aluminum pan manufactured by the same company and sealed, and the measurement was started at 200 ° C. under a nitrogen flow of 50 mL / min, and cooled to 30 ° C. at a rate of 20 ° C. / min. The temperature was held at 30 ° C. for 3 minutes, and then increased to 200 ° C. at a rate of 20 ° C. / min. From the DSC data during the temperature increase, the extrapolated glass transition onset temperature, which is the temperature at the intersection of a straight line extending the baseline on the low temperature side to the high temperature side and a tangent drawn at a point where the gradient of the curve of the stepwise change part of the glass transition is maximum, was obtained, and this was taken as the glass transition temperature.

Izod impact strength After the resin pellets were vacuum dried at 90°C for 5 hours or more, an Izod test piece was prepared using a small injection molding machine C, Mobile-0813 (manufactured by Shinko Selvic Co., Ltd.). A notch with a tip radius of 0.25 mm was made in the test piece using a cutter. In accordance with ASTM D256, the Izod impact strength (unit: kJ/m ² ) was measured at 23°C using a notched test piece with a thickness of 3.2 mm. A larger Izod impact strength value indicates better impact resistance.

(Raw materials used)
The abbreviations and manufacturers of the compounds used in the following Examples and Production Examples are as follows.
[Dihydroxy Compounds]
・ISB: Isosorbide (manufactured by Rocket Fleuret)
PO3G2000: Polytrimethylene ether glycol, measured number average molecular weight 2005 (manufactured by ALLESSA, product name: VELVETOL)
PO3G1000: Polytrimethylene ether glycol, measured number average molecular weight 1043 (manufactured by ALLESSA)
PO3G500: Polytrimethylene ether glycol, measured number average molecular weight 514 (manufactured by ALLESSA)
CHDM: 1,4-cyclohexanedimethanol (SK Chemical Co., Ltd.)
[Carbonate diester]
DPC: Diphenyl carbonate (manufactured by Mitsubishi Chemical Corporation)
[Impact resistance improver]
Acrylic core-shell rubber: butyl acrylate, methyl methacrylate, styrene copolymer (core: butyl acrylate, shell: methyl methacrylate, styrene)

Example 1
Polymerization was carried out using a batch polymerization apparatus consisting of two vertical stirring reactors equipped with stirring blades and reflux condensers. 56.65 parts by weight (0.388 mol) of ISB, 4.94 parts by weight (0.002 mol) of PO3G2000, 23.96 parts by weight (0.166 mol) of CHDM, 119.15 parts by weight (0.556 mol) of DPC, and 2.94 x 10 ^-4 parts by weight (1.67 x 10 ^-6 mol) of calcium acetate monohydrate as a catalyst were charged into the reactor. After the inside of the reactor was substituted with nitrogen under reduced pressure, it was heated with a heat medium, and stirring was started when the internal temperature reached 100 ° C. 40 minutes after the start of the temperature rise, the internal temperature was allowed to reach 210 ° C., and the pressure was controlled to maintain this temperature, and the pressure was reduced to 13.3 kPa in 90 minutes after reaching 210 ° C. Phenol vapor by-produced during the polymerization reaction was introduced into a reflux condenser at 110°C, a small amount of monomer components contained in the phenol vapor was returned to the reactor, and uncondensed phenol vapor was introduced into a condenser at 45°C and collected. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, the temperature increase and pressure reduction in the second reactor were started, and the internal temperature was 220°C and the pressure was 20 kPa in 40 minutes. Thereafter, polymerization was allowed to proceed while further decreasing the pressure until a predetermined stirring power was reached. When the predetermined power was reached, nitrogen was introduced into the reactor to restore the pressure, and the produced polycarbonate was extruded into water, and the strands were cut to obtain pellets. The results of the various evaluations described above are shown in Table 1.
In Table 1, the percentage (wt%) of each component in the column for polycarbonate resin indicates the percentage (weight ratio) of structural units derived from each component constituting the polycarbonate resin. This also applies to the following examples and comparative examples.

Example 2
The same procedure as in Example 1 was repeated, except that the raw materials used were 53.67 parts by weight (0.367 mol) of ISB, 9.87 parts by weight (0.005 mol) of PO3G2000, 22.70 parts by weight (0.157 mol) of CHDM, 113.43 parts by weight (0.530 mol) of DPC, and 2.80×10 ⁻⁴ parts by weight (1.59×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 1)
The same procedure as in Example 1 was repeated except that the raw materials were changed to 84.90 parts by weight (0.581 mol) of ISB, 126.94 parts by weight (0.593 mol) of DPC, and 1.54×10 ⁻⁴ parts by weight (8.71×10 ⁻⁷ mol) of calcium acetate monohydrate, and the final polymerization temperature was changed to 230°C.

(Comparative Example 2)
The same procedure as in Example 1 was repeated except that the raw materials were changed to 80.65 parts by weight (0.552 mol) of ISB, 4.94 parts by weight (0.002 mol) of PO3G2000, 119.94 parts by weight (0.560 mol) of DPC, and 2.93× ^10-4 parts by weight (1.66× ^10-6 mol) of calcium acetate monohydrate, and the final polymerization temperature was changed to 230° C.

(Comparative Example 3)
The same procedure as in Example 1 was repeated except that the raw materials were changed to 75.56 parts by weight (0.517 mol) of ISB, 10.47 parts by weight (0.020 mol) of PO3G500, 115.70 parts by weight (0.540 mol) of DPC, and 2.84×10 ⁻⁴ parts by weight (1.61×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 4)
The same procedure as in Example 1 was repeated except that the raw materials charged were 70.47 parts by weight (0.482 mol) of ISB, 16.18 parts by weight (0.031 mol) of PO3G500, 110.58 parts by weight (0.516 mol) of DPC, and 9.05×10 ⁻⁴ parts by weight (5.14×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 5)
The same procedure as in Example 1 was repeated except that the raw materials were changed to 59.63 parts by weight (0.408 mol) of ISB, 25.22 parts by weight (0.175 mol) of CHDM, 126.12 parts by weight (0.589 mol) of DPC, and 1.54×10 ⁻⁴ parts by weight (8.74×10 ⁻⁷ mol) of calcium acetate monohydrate.

(Comparative Example 6)
The same procedure as in Example 1 was repeated, except that the raw materials used were 56.65 parts by weight (0.388 mol) of ISB, 4.88 parts by weight (0.005 mol) of PO3G1000, 23.96 parts by weight (0.166 mol) of CHDM, 119.63 parts by weight (0.558 mol) of DPC, and 2.95×10 ⁻⁴ parts by weight (1.68×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 7)
The same procedure as in Example 1 was repeated, except that the raw materials used were 56.65 parts by weight (0.388 mol) of ISB, 4.76 parts by weight (0.009 mol) of PO3G500, 23.96 parts by weight (0.166 mol) of CHDM, 120.61 parts by weight (0.563 mol) of DPC, and 2.98×10 ⁻⁴ parts by weight (1.69×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 8)
The same procedure as in Example 1 was repeated, except that the raw materials used were 53.67 parts by weight (0.367 mol) of ISB, 9.52 parts by weight (0.019 mol) of PO3G500, 22.70 parts by weight (0.157 mol) of CHDM, 116.35 parts by weight (0.543 mol) of DPC, and 2.87×10 ⁻⁴ parts by weight (1.63×10 ⁻⁶ mol) of calcium acetate monohydrate.

(Comparative Example 9)
90 parts by weight of the polycarbonate resin pellets obtained in Comparative Example 5 were blended with 10 parts by weight of an acrylic core-shell rubber as an impact resistance improver, and then extrusion kneading was carried out using a vacuum vented twin-screw extruder TEX30HSS (manufactured by Japan Steel Works, Ltd.) at a cylinder temperature of 240°C and an extrusion rate of 12 kg/hr to obtain pellets of a polycarbonate resin composition. The obtained polycarbonate resin composition was subjected to the above-mentioned various evaluations.

Claims (6)

A polycarbonate resin comprising at least a structural unit (A) represented by the following formula (1), a structural unit (B) represented by the following formula (2), and a structural unit (C) derived from an aliphatic dihydroxy compound and/or an alicyclic dihydroxy compound,
A polycarbonate resin containing 40% by weight or more and 80% by weight or less of the structural unit (A) and 1% by weight or more and 20% by weight or less of the structural unit (B), wherein the number average molecular weight of the structural unit (B) is 1,200 or more and 5,000 or less.

In formula (2), n is an integer of 2 or more. The polycarbonate resin according to claim 1, containing 1% by weight or more and 40% by weight or less of the structural unit (C). The polycarbonate resin according to claim 1 or 2, which contains, as the structural unit (C), 1 wt % or more and 40 wt % or less of a structural unit represented by the following formula (3):

The polycarbonate resin according to any one of claims 1 to 3, having a glass transition temperature of 90°C or higher and 140°C or lower. A molded article obtained by molding the polycarbonate resin according to any one of claims 1 to 4. A method for producing the polycarbonate resin according to any one of claims 1 to 4, comprising a step of polycondensing raw materials, by transesterification, a dihydroxy compound forming the structural unit (A) represented by formula (1), a dihydroxy compound forming the structural unit (B) represented by formula (2), a dihydroxy compound forming the structural unit (C), and a monomer containing a carbonate diester;
In the step, the dihydroxy compound that forms the structural unit (B) represented by the formula (2) is polytrimethylene ether glycol, and the number average molecular weight of this polytrimethylene ether glycol is 1,200 or more and 5,000 or less.