Modified polycarbonate, method for producing modified polycarbonate, and resin composition

Abstract

Provided is a modified polycarbonate which has a structural unit represented by formula (1) in the main chain. The modified polycarbonate exhibits excellent fluidity during molding, and enables easy production of a molded body at low cost without deteriorating physical properties of the molded body such as strength, durability and heat resistance. (1): -R-S-S-R- (In formula (1), each R independently represents a divalent aliphatic hydrocarbon group which may contain a hetero atom, or a monocyclic divalent aromatic hydrocarbon group which may contain a hetero atom.)

Description

Modified polycarbonate, method for producing modified polycarbonate, and resin composition

[0001] The present invention relates to a modified polycarbonate, a method for producing the modified polycarbonate, and a resin composition.

[0002] Polycarbonate resins have excellent mechanical and thermal properties and are therefore used in a wide range of fields, including electrical, electronic, and office automation equipment, optical components, precision machinery, automobiles, security and medical care, building materials, and miscellaneous goods. However, polycarbonate resins usually have a high melt viscosity, which means that they have poor fluidity during molding, i.e., poor melt fluidity, resulting in poor moldability.

[0003] In recent years, in order to overcome the above drawbacks, efforts have been made to develop polycarbonates that have excellent melt fluidity and do not impair the physical properties such as strength, durability, and heat resistance of the resulting molded articles. For example, Patent Document 1 describes a polycarbonate that contains two types of structural units represented by a specific formula and has a specific viscosity of 0.12 to 0.40.

[0004] Furthermore, development of polycarbonates having various functions is also progressing. Patent Document 2 discloses a dynamic covalent bond compound having a diaminopolysulfide basic skeleton as a compound having external stimulus responsiveness and / or self-repairing function. Patent Document 2 also discloses that the dynamic covalent bond compound can be polycarbonate.

[0005] Patent Document 3 discloses a degradable oligomeric polymer in which a plurality of oligomers such as polycarbonate are linked together via linking parts made of chemical bonds that can be repeatedly cleaved and recombined by a predetermined treatment that does not affect the oligomers.

[0006] Japanese Unexamined Patent Publication No. 2014-214220 Japanese Unexamined Patent Publication No. 2017-202980 Unexamined Japanese Patent Application No. 7-247364

[0007] However, the above-mentioned conventional techniques have room for improvement from the viewpoint of producing a modified polycarbonate at low cost and simply that has excellent flowability during molding and does not deteriorate the physical properties such as strength, durability, and heat resistance of the resulting molded article. One aspect of the present invention aims to realize a modified polycarbonate that has excellent flowability during molding and does not deteriorate the physical properties such as strength, durability, and heat resistance of the resulting molded article, and that can be produced at low cost and simply.

[0008] A modified polycarbonate according to one embodiment of the present invention has, in its main chain, structural units represented by the following formula (1): -R-S-S-R- (1) (In formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom).

[0009] A resin composition according to one embodiment of the present invention comprises a raw material polycarbonate, and a compound containing a structural unit represented by the following formula (1) and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by the following formula (2) and a group capable of reacting with a carbonate group to form a bond: -R-S-S-R- (1) (in formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom) -R-SH (2) (in formula (2), R is the same as R in formula (1)).

[0010] According to one aspect of the present invention, it is possible to provide a modified polycarbonate that has excellent flowability during molding, does not deteriorate the physical properties such as strength, durability, and heat resistance of the resulting molded article, and can be produced easily and at low cost.

[0011] 1 shows the DSC curves obtained from the DSC analysis of the comparative polycarbonate described in Comparative Example 1. 2 shows the DSC curves obtained from the DSC analysis of the modified polycarbonate described in Example 1. 3 shows the DSC curves obtained from the DSC analysis of the modified polycarbonate described in Example 3.

[0012] One embodiment of the present invention will be described below, but the present invention is not limited thereto. Furthermore, all academic literature and patent documents described in this specification are incorporated herein by reference. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more and B or less." Furthermore, in this specification, polycarbonates into which specific structural units have been introduced and in which properties such as melt flowability have been improved are also referred to as "modified polycarbonates."

[0013] 1. Modified Polycarbonate A modified polycarbonate according to one embodiment of the present invention (hereinafter also referred to as "the present modified polycarbonate") has, in its main chain, a structural unit represented by the following formula (1): -R-S-S-R- (1) (in formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom).

[0014] As a result of extensive research, the present inventors have found that disulfide groups having specific structures can be introduced into polycarbonates at low cost and easily. They have also found that modified polycarbonates into which disulfide groups having specific structures have been introduced have excellent flowability during molding and do not impair the physical properties, such as strength, durability, and heat resistance, of the resulting molded articles, and have completed the present invention.

[0015] Here, the disulfide bond (S-S bond) in the structural unit represented by the following formula (1) corresponds to a dynamic covalent bond, as shown in Patent Document 2. When molding using this modified polycarbonate, the modified polycarbonate is heated, melt-kneaded, and then cooled. The heating during the molding process cleaves the S-S bond, resulting in decomposition into low-molecular-weight polycarbonate. It is known that melts made of low-molecular-weight polymers have better fluidity. Therefore, this modified polycarbonate has excellent melt fluidity during molding.

[0016] Furthermore, conventional polycarbonates decompose into low-molecular-weight polycarbonates when heated during molding, which can result in reduced physical properties such as strength, durability, and heat resistance of the resulting molded article. In contrast, with the present modified polycarbonate, the S-S bonds that were cleaved during molding are recombined upon cooling. This prevents the deterioration of physical properties such as strength, durability, and heat resistance of the molded article that would otherwise result from decomposition into the low-molecular-weight polycarbonate.

[0017] Furthermore, to produce the polycarbonate (modified polycarbonate) described in Patent Document 1, a diol component containing a structural unit in which naphthalene rings substituted with a group represented by formula (I) described in Patent Document 1 are linked together by a linking group such as a disulfide group is used as a raw material. The diol component requires a complex manufacturing process, is not easily available, and is expensive. Therefore, the modified polycarbonate described in Patent Document 1 has the problems of being difficult to manufacture and high in cost. On the other hand, to produce this modified polycarbonate, a compound containing a structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond (hereinafter also referred to as "compound (1A)") and / or a compound containing a structural unit represented by formula (2) below and a group capable of reacting with a carbonate group to form a bond (hereinafter also referred to as "compound (2A)") is used. Compounds (1A) and (2A) are easier to manufacture and obtain, and less expensive, than the diol component and other raw materials used to produce the polycarbonate described in Patent Document 1. Therefore, the present modified polycarbonate can be produced easily and at low cost.

[0018] In addition, the dynamic covalent bond compound described in Patent Document 2 has the problem of low heat resistance because the S-S bond in the diaminopolysulfide basic skeleton cleaves at a low temperature of around 100°C. On the other hand, the S-S bond in the structural unit represented by formula (1) cleaves at a higher temperature and is more stable than the S-S bond in the diaminopolysulfide basic skeleton in the dynamic covalent bond compound described in Patent Document 2. Therefore, the present modified polycarbonate has better heat resistance than the dynamic covalent bond compound described in Patent Document 2, and is superior in physical properties such as the strength, durability, and heat resistance of the molded product.

[0019] As described above, the present modified polycarbonate has excellent fluidity during molding, does not deteriorate the physical properties such as strength, durability, and heat resistance of the resulting molded body, and can be produced easily and at low cost.

[0020] <Configuration of the present modified polycarbonate> The present modified polycarbonate has a main chain composed of structural units of a polycarbonate structure in addition to the structural unit represented by formula (1). In other words, the present modified polycarbonate is a polycarbonate having a main chain containing a structure in which the structural unit represented by formula (1) is inserted between two structural units of a polycarbonate structure.

[0021] (Structural Unit Represented by Formula (1)) The group represented by R in the structural unit represented by Formula (1) is not particularly limited as long as it is a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom. Furthermore, in the structural unit represented by Formula (1), the carbon (C) in the group represented by R is bonded to the sulfur (S) in the disulfide bond (S-S). The group represented by R may be, for example, one or more groups selected from the group consisting of a substituted or unsubstituted phenylene group and a substituted or unsubstituted alkylene group. Examples of the alkylene group include a methylene group, an ethylene group, and a propylene group. More specifically, the group represented by R is preferably, for example, one or more groups selected from the group consisting of a methylene group, an ethylene group, a propylene group, a 1-aminoethylene group, a 1-(carbonylamino)ethylene group, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a thiazole ring, and a phenylene group. The two R's in the structural unit represented by formula (1) may be the same or different. When the main chain of the present modified polycarbonate contains multiple structural units represented by formula (1), all of the structural units represented by formula (1) may be the same or different.

[0022] When the content of the structural unit represented by formula (1) in the main chain of the present modified polycarbonate is high, the present modified polycarbonate is decomposed into a polycarbonate with a lower molecular weight by heating during molding, resulting in a melt with better fluidity. Therefore, the higher the content of the structural unit represented by formula (1) in the main chain, the better the melt fluidity of the present modified polycarbonate. In this specification, the content of the structural unit represented by formula (1) is expressed as the ratio of the number of moles of the structural unit represented by formula (1) to the number of moles of structural units other than the structural unit represented by formula (1) in the main chain (hereinafter also referred to as the "proportion X of the structural unit represented by formula (1)"). From the viewpoint of providing the above-mentioned better melt fluidity, the proportion X of the structural unit represented by formula (1) is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and even more preferably 0.01 mol% or more. The structural units in the main chain other than the structural unit represented by formula (1) are usually structural units derived from the monomers that form the polycarbonate structure in the main chain, and the number of moles of the structural units in the main chain other than the structural unit represented by formula (1) corresponds to the number of moles of the structural units derived from the monomers that constitute the raw polycarbonate in the method for producing a modified polycarbonate according to one embodiment of the present invention described below.

[0023] On the other hand, when the content of the structural unit represented by formula (1) in the main chain of the present modified polycarbonate is below a specific value, the melt fluidity of the present modified polycarbonate becomes excessively high, which can prevent a decrease in handleability during molding. From the viewpoint of preventing a decrease in handleability during molding, the proportion X of the structural unit represented by formula (1) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less.

[0024] The method for measuring and calculating the proportion X of the structural unit represented by formula (1) in the main chain is not particularly limited, and known methods can be used. For example, an example of a method for measuring and calculating the proportion X of the structural unit represented by formula (1) in the main chain is to calculate the proportion X of the structural unit represented by formula (1) in the main chain based on the raw materials used in the production of the present modified polycarbonate. Specific examples include the following methods (a1) to (c1).

[0025] (a1) Among the structural units constituting the main chain of a starting polycarbonate described below, the number of moles of structural units other than the structural unit represented by formula (1) is calculated as the number of moles of structural units in the main chain other than the structural unit represented by formula (1). Note that when the main chain of the starting polycarbonate does not have the structural unit represented by formula (1), the number of moles of structural units constituting the main chain of the starting polycarbonate is calculated as the number of moles of structural units in the main chain other than the structural unit represented by formula (1).

[0026] (b1) The number of moles of the structural unit represented by formula (1) in the main chain is calculated as the sum of the number of moles (amount used) of the compound (1A) described below and the number of moles (amount used) of the compound (2A) described below × ½ and the number of moles of the structural unit represented by formula (1) in the main chain of the starting polycarbonate.

[0027] (c1) The ratio of the number of moles of the structural unit represented by formula (1) to the number of moles of structural units other than the structural unit represented by formula (1) in the main chain is calculated, and this is defined as the ratio X of the structural unit represented by formula (1) in the main chain.

[0028] The number of moles of structural units other than the structural unit represented by formula (1) among the structural units constituting the main chain of the starting polycarbonate in (a1) can be measured and calculated, for example, based on the number of moles of monomers that do not form the structural unit represented by formula (1) among the monomers used in preparing the starting polycarbonate.

[0029] Furthermore, by adjusting the type of raw material polycarbonate (the number of moles of the structural unit represented by formula (1) in the main chain) and the amount of raw material used in producing the modified polycarbonate, the proportion X of the structural unit represented by formula (1) in the modified polycarbonate produced, calculated by the methods (a1) to (c1), can be controlled.

[0030] As a modified example of the methods (a1) to (c1), for example, the method (a1) to (c1) may be modified by additionally carrying out the step (a0) described below, and carrying out the step (b1') described below instead of the step (b1). The "actually produced resin composition" in (a0) described below is a resin composition consisting of the modified polycarbonate and unreacted raw materials, which is typically obtained when producing a modified polycarbonate.

[0031] (a0) The number of moles of the compound (1A) described below and the number of moles of the compound (2A) described below contained in the actually produced resin composition are measured. The number of moles of the compound (1A) described below contained in the actually produced resin composition is referred to as the "number of moles of the compound (1A) described below (unreacted)," and the number of moles of the compound (2A) described below is referred to as the "number of moles of the compound (2A) described below (unreacted)."

[0032] (b1') The total value of {the number of moles of the compound (1A) described below (used amount)−the number of moles of the compound (1A) described below (unreacted)} and {the number of moles of the compound (2A) described below (used amount)−the number of moles of the compound (2A) described below (unreacted)} × 1 / 2 and the number of moles of the structural unit represented by formula (1) in the main chain of the starting polycarbonate is calculated as the number of moles of the structural unit represented by formula (1) in the main chain.

[0033] By using the method of the modified example, the theoretical value of the number of moles of the structural unit represented by formula (1) in the main chain, calculated only from the amount of raw material used, can be corrected based on the actual yield of the reaction to introduce the disulfide compound. As a result, by using the method of the modified example, the proportion X of the structural unit represented by formula (1) in the main chain of the modified carbonate actually produced can be calculated more accurately.

[0034] In the (a0), the method for measuring the number of moles of the compound (1A) described below and the number of moles of the compound (2A) described below contained in the actually produced resin composition can be a known method, and is not particularly limited. As a method for measuring the number of moles of the compound (1A) described below and the number of moles of the compound (2A) described below contained in the actually produced resin composition, for example, a known method such as mass spectrometry can be used.

[0035] Another method for measuring and calculating the proportion X of the structural unit represented by formula (1) in the main chain can be, for example, the following method: NMR analysis is performed on the modified polycarbonate, and the proportion X of the structural unit represented by formula (1) in the main chain is measured and calculated based on the resulting NMR spectrum.

[0036] By using the above-mentioned alternative method, the actual proportion of the structural unit represented by the above-mentioned formula (1) in the modified polycarbonate can be measured and calculated.

[0037] (Constituent unit of polycarbonate structure) The constituent unit of the polycarbonate structure in the present modified polycarbonate can be a constituent unit that generally constitutes a polycarbonate, and is not particularly limited.The constituent unit of the polycarbonate structure can be, for example, a constituent unit that constitutes a polycarbonate resin produced by a method of interfacial polycondensation of a divalent phenol and a carbonyl halide, or a method of melt polymerization of a divalent phenol and a carbonate diester (ester exchange method).That is, the constituent unit of the polycarbonate structure can be a constituent unit derived from the divalent phenol, carbonyl halide and carbonate diester listed below.

[0038] Examples of the dihydric phenol include 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)ketone, hydroquinone, resorcinol, and catechol. Among these dihydric phenols, bis(hydroxyphenyl)alkanes are preferred, and 2,2-bis(4-hydroxyphenyl)propane is particularly preferred.

[0039] Examples of the carbonyl halide and carbonate diester include carbonyl halides, carbonyl esters, haloformates, etc. Specific examples include phosgene, dihaloformates of dihydric phenols, diaryl carbonates such as diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, and m-cresyl carbonate, and aliphatic carbonate compounds such as dimethyl carbonate, diethyl carbonate, diisopropyl carbonate, dibutyl carbonate, diamyl carbonate, and dioctyl carbonate.

[0040] The modified polycarbonate may have a structure consisting of only the main chain, i.e., the molecular structure of the polymer chain may be a linear structure, or may have a branched structure. Examples of branching agents for introducing such branched structures include 1,1,1-tris(4-hydroxyphenyl)ethane, α,α',α"-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene, phloroglucin, trimellitic acid, and isatin bis(o-cresol).

[0041] <Uses of the Modified Polycarbonate> The modified polycarbonate has excellent flowability during molding, and can therefore be suitably molded. Therefore, by molding the modified polycarbonate, molded articles with excellent moldability can be suitably produced. The molding method for molding the modified polycarbonate is not particularly limited, and any common molding method can be used. Examples of such molding methods include extrusion molding, injection molding, calendaring, rotational molding, and blow molding. Examples of such extrusion molding methods include round bar molding, profile extrusion molding, coextrusion molding, foam extrusion molding, inflation molding, and cast molding. Examples of the injection molding method include cold runner type injection molding and hot runner type injection molding, as well as injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including the case where supercritical fluid is injected), insert molding, in-mold coating molding, heat-insulating mold molding, rapid heating and cooling mold molding, two-color molding, sandwich molding, and ultra-high speed injection molding.

[0042] Specifically, extrusion-molded articles having various shapes can be produced by molding the present modified polycarbonate by an extrusion molding method using a mold having various shapes. Furthermore, injection-molded articles having various shapes can be produced by molding the present modified polycarbonate by an injection molding method using a mold having various shapes. Furthermore, sheet- or film-shaped molded articles can be produced by molding the present modified polycarbonate by an inflation method, a calendar method, or a cast molding method. Additionally, hollow molded articles can also be produced by molding the present modified polycarbonate by rotational molding or blow molding.

[0043] Molded articles obtained by molding this modified polycarbonate have excellent physical properties such as strength, durability, and heat resistance, making them suitable for a wide range of applications, including various housings, hard-coated products, glazing materials, light diffusion plates, optical disk substrates, light guide plates, medical materials, and miscellaneous goods. Specific examples of the molded article include exterior materials for office automation equipment and home appliances, various containers, miscellaneous goods, such as exterior materials for personal computers, notebook computers, game consoles, display devices (CRT, liquid crystal, plasma, projectors, organic EL, etc.), mice, printers, copiers, scanners, and fax machines (including multifunction devices thereof), keyboard keys, molded switch products, personal digital assistants (so-called PDAs), mobile phones, portable books (dictionaries, etc.), portable televisions, drives for recording media (CDs, MDs, DVDs, Blu-ray discs, hard disks, etc.), readers for recording media (IC cards, smart media, memory sticks, etc.), optical cameras, digital cameras, parabolic antennas, power tools, VTRs, irons, hair dryers, rice cookers, microwave ovens, audio equipment, lighting equipment, refrigerators, air conditioners, air purifiers, negative ion generators, and typewriters. The molded articles are also useful for trays, cups, plates, shampoo bottles, office equipment housings, cosmetic bottles, beverage bottles, oil containers, injection molded articles (golf tees, cotton swab cores, candy sticks, brushes, toothbrushes, helmets, syringes, plates, cups, combs, razor handles, tape cassettes and cases, disposable spoons and forks, stationery such as ballpoint pens, etc.), etc.

[0044] Furthermore, the molded article can be used in a wide range of applications, such as binding tape (binding band), prepaid cards, balloons, pantyhose, hair caps, sponges, cellophane tape, umbrellas, raincoats, plastic gloves, hair caps, ropes, tubes, foam trays, foam cushioning materials, cushioning materials, packaging materials, and cigarette filters.

[0045] Furthermore, the molded article can also be used for vehicle parts such as lamp sockets, lamp reflectors, lamp housings, instrument panels, center console panels, deflector parts, car navigation parts, car audiovisual parts, and automobile computer parts.

[0046] 2. Method for Producing Modified Polycarbonate A production method according to one embodiment of the present invention (hereinafter also referred to as "this production method") is a method for producing this modified polycarbonate, and includes a modification step of reacting a raw material polycarbonate with a compound containing a structural unit represented by formula (1) above and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by formula (2) below and a group capable of reacting with a carbonate group to form a bond: -R-SH (2) (in formula (2), R is the same as R in formula (1) above).

[0047] Regarding the matters relating to this manufacturing method, the matters described in the section [1. Modified Polycarbonate] are appropriately cited for the components common to this modified polycarbonate. In the following, the group capable of reacting with the carbonate group to form a bond is also referred to as the "reactive group."

[0048] The present production method has the effect of enabling the aforementioned modified polycarbonate, i.e., a modified polycarbonate that has excellent fluidity during molding and does not deteriorate the physical properties such as strength, durability, and heat resistance of the resulting molded body, to be produced simply and at low cost.

[0049] <Modification Step> The modification step in this production method is a step of reacting a raw polycarbonate with the compound (1A) and / or the compound (2A). In the modification step, the structural unit represented by the formula (1) is inserted between the structural units derived from the raw polycarbonate, thereby producing the modified polycarbonate.

[0050] (Raw Material Polycarbonate) The raw material polycarbonate is a polycarbonate before the structural unit represented by formula (1) is inserted in the modification step of the present production method. Specifically, the raw material polycarbonate is a polycarbonate having a lower content of the structural unit represented by formula (1) than the modified polycarbonate produced by the present production method. Furthermore, the raw material polycarbonate may be a polycarbonate that does not contain the structural unit represented by formula (1) and does not have an S—S bond in the main chain.

[0051] The raw polycarbonate is not particularly limited as long as it is a polycarbonate with a lower content of the structural unit represented by formula (1) than the modified polycarbonate. A typical polycarbonate can be used as the raw polycarbonate, and examples thereof include polycarbonate resins produced by interfacial polycondensation of a dihydric phenol and a carbonyl halide as monomers, or by melt polymerization of a dihydric phenol and a carbonate diester as monomers (ester interchange method). The dihydric phenol, the carbonyl halide, and the carbonate diester may be the dihydric phenol, the carbonyl halide, and the carbonate diester exemplified in the section [1. Modified Polycarbonate].

[0052] The raw material polycarbonate may be a commercially available polycarbonate or may be a polycarbonate prepared separately. Therefore, the present production method may include a step of preparing the raw material polycarbonate. The method for preparing the raw material polycarbonate is not particularly limited, and a general method for preparing polycarbonate may be used.

[0053] (Compound (1A)) The compound (1A) is a compound containing a structural unit represented by the formula (1) and a reactive group. For the structural unit represented by the formula (1), the details shown in the section [1. Modified polycarbonate] are incorporated herein by reference.

[0054] The reactive group is not particularly limited and may be, for example, one or more groups selected from the group consisting of a hydroxy group, a carboxy group, an alkoxycarbonyl group, a halogenated acyl group, and an amino group. Compound (1A) usually has reactive groups at both ends. The reactive groups at both ends may be the same or different.

[0055] The compound (1A) is not particularly limited as long as it contains the structural unit represented by formula (1) and a reactive group. Examples of the compound (1A) include one or more compounds selected from the group consisting of dimethyl-3,3'-dithiodipropionate, L-cystine dimethyl ether dihydrochloride, bis(2-hydroxyethyl)disulfide, cystine, oxidized glutathione, bis(4-hydroxyphenyl)disulfide, 3,3'-dihydroxyphenyl disulfide, 4,4'-dithiodianiline, 3,3'-dithiodipropionic acid, cystamine, 4,4'-dithiodibutyric acid, 2,2'-dithiodibenzoic acid, 6,6'-dithiodinicotinic acid, dithiodiglycolic acid, and bis(4-benzenecarboxylic acid)disulfide.

[0056] (Compound (2A)) The compound (2A) is a compound containing a structural unit represented by the formula (2) and a reactive group. As with the structural unit represented by the formula (1) in the compound (1A), the R in the structural unit represented by the formula (2) is as described in the section [1. Modified polycarbonate]. The reactive group in the compound (2A) is as described in the section [1A].

[0057] The compound (2A) is a precursor of the compound (1A), and the -SH groups in two compounds (2A) can be oxidized by the action of oxygen in the air and bonded to each other to form an -S-S- bond, thereby forming the compound (1A). Thus, in the modification step, a structural unit represented by the formula (1) is formed from two molecules of the compound (2A), and the formed structural unit is inserted between the constituent units of the raw material polycarbonate, thereby preparing the modified carbonate resin.

[0058] The compound (2A) is not particularly limited as long as it contains the structural unit represented by formula (2) and a reactive group. Examples of the compound (2A) include one or more compounds selected from the group consisting of methyl 3-mercaptopropanoate, L-cysteine ​​ethyl ester hydrochloride, 2-mercaptoethanol, cysteine, acetylcysteine, p-mercaptophenol, thioglycolic acid, 4-mercaptoaniline, 4-mercaptobutyric acid, and p-mercaptobenzoic acid. Furthermore, the compound (2) can react with any mercapto group-containing compound to form an —S—S— bond, i.e., the structural unit represented by formula (1). Therefore, by allowing a compound having multiple mercapto groups in one molecule to coexist with the compound (2A) and the starting polycarbonate, multiple structural units represented by formula (1) can be introduced into the main chain of the starting polycarbonate. Such a compound having multiple mercapto groups in one molecule is not particularly limited, and examples thereof include one or more selected from the group consisting of 1,3,5-benzenetrithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, trithiocyanuric acid, bismuthiol, ethylene glycol bis(3-mercaptopropionate), 4,4'-biphenyldithiol, dithioerythritol, 1,6-hexanedithiol, pentaerythritol tetrakis(mercaptoacetate), and trimethylolpropane tris(thioglycolate). When these compounds having multiple mercapto groups in one molecule are added, the proportion of the structural unit X represented by formula (1) is calculated by appropriately correcting the amount added.

[0059] In the modification step, the reactive groups in the compound (1A) and / or the compound (2A) undergo nucleophilic attack on the carbonate groups in the starting polycarbonate. The nucleophilic attack cleaves the main chain of the starting polycarbonate, and a structural unit represented by formula (1) is inserted into the cleaved site in the main chain through a transesterification reaction, thereby preparing the modified polycarbonate.

[0060] In the modification step, the insertion of the structural unit represented by the formula (1), i.e., the S—S bond, can be confirmed, for example, based on the results of NMR measurement performed on the resulting polycarbonate, a DSC curve obtained as a result of DSC measurement, or the like.

[0061] As described above, when the compound (2A) is used, the structural unit represented by the formula (1) is formed from two molecules of the compound (2A) in the modification step, and the modified polycarbonate is prepared. Specifically, the modified polycarbonate is prepared, for example, by the following steps (i) and (ii):

[0062] (i) The compound (1A) is produced from two molecules of the compound (2A), and the reactive group in the produced compound (1A) performs a nucleophilic attack on the carbonate group, thereby preparing the present modified polycarbonate.

[0063] (ii) The reactive group in compound (2A) undergoes nucleophilic attack on the carbonate group, producing an intermediate polycarbonate having an —SH group at least at one end. The intermediates then bond to each other via their —SH groups to form an —S—S— bond, thereby preparing the modified polycarbonate.

[0064] Therefore, in the modified polycarbonate produced by this production method, 1 mole of the structural unit represented by the formula (1) derived from 1 mole of compound (1A) is introduced into the raw polycarbonate, and 1 mole of the structural unit represented by the formula (1) derived from 2 moles of compound (2A) is introduced into the raw polycarbonate. Here, the modified polycarbonate in which the proportion X of the structural unit represented by the formula (1) is within the preferred range shown in the column [1. Modified Polycarbonate] has better melt fluidity and is more excellent in handleability during molding. In terms of producing the modified polycarbonate having the above-mentioned better melt fluidity and being more excellent in handleability during molding, the value represented by the following mathematical formula (3) is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and even more preferably 0.01 mol% or more. Furthermore, the value represented by the following mathematical formula (3) is preferably 30 mol % or less, more preferably 20 mol % or less, and even more preferably 10 mol % or less: [{A+(B / 2)+C} / D]×100 (3) (In mathematical formula (3), A is the amount (mol) of the compound used that contains the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond, B is the amount (mol) of the compound used that contains the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond, C is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate, and D is the number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate).

[0065] On the other hand, when compound (2A) is used, the -SH group in compound (2A) may perform nucleophilic attack on the carbonate group, resulting in a risk of a side reaction. From the viewpoint of preventing the side reaction, it is preferable to use only compound (1A) as the compound to be reacted with the raw material polycarbonate in the modification step, without using compound (2A). When compound (2A) is used, it is preferable to form disulfide bonds by reacting compound (2A) with itself and / or compound (2A) with a compound having multiple mercapto groups in one molecule before reacting compound (2A) with the raw material polycarbonate.

[0066] In the modification step, a catalyst may be used as needed. The catalyst is not particularly limited as long as it is a catalyst that can promote the transesterification reaction by the nucleophilic attack, and known catalysts can be used. Examples of the catalyst include titanium tetraisopropoxide, titanium tetrabutoxide, lithium acetate, magnesium acetate, zinc hydroxide, zinc chloride, manganese chloride, hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, sodium hydroxide, sodium methoxide, calcium hydroxide, sulfonic acid immobilized catalyst, dibutyltin diacetate, aluminum tributoxide, tin tetrabutoxide, and antimony butoxide. The amount of the catalyst used is not particularly limited, and may be, for example, 1×10 based on the weight of the raw material polycarbonate. －６ The amount may be from 1 part by weight to 1 part by weight, and preferably from 0.0001 part by weight to 0.1 part by weight. Note that, when the catalyst is used, the resulting modified polycarbonate may be colored and / or may have reduced thermal stability, so it is preferable not to use a catalyst whenever possible.

[0067] The method (process) for carrying out the modification step is not particularly limited, and examples thereof include a solution process, a melt process, etc. The solution process is a process in which a raw material polycarbonate is reacted with the compound (1A) and / or the compound (2A) in a solution state, and specifically, the process can be carried out, for example, by a method including the following steps (A1) to (E1):

[0068] (A1) A step of dissolving a raw material polycarbonate in an appropriate solvent to prepare a raw material polycarbonate solution.

[0069] (B1) A step of preparing a reaction solution by adding the compound (1A) and / or the compound (2A), and, if necessary, the catalyst, to the raw material polycarbonate solution prepared in the step (A1).

[0070] (C1) A step of stirring the reaction solution prepared in step (B1) to react the raw polycarbonate with compound (1A) and / or compound (2A) to prepare the modified carbonate solution.

[0071] (D1) A step of adding an extraction solvent to the modified carbonate solution prepared in step (C1) to reprecipitate the modified carbonate, and then separating the modified carbonate, or a step of distilling off the solvent used in step (A1) to extract the modified carbonate as a solid.

[0072] (E1) A step of drying the modified carbonate separated in step (D1).

[0073] The solvent used in step (A1) is not particularly limited as long as it can dissolve the raw material polycarbonate, and examples thereof include dichloromethane, 1,2-dichloroethane, chloroform, chlorobenzene, ethyl acetate, methyl ethyl ketone, tetrahydrofuran, and dimethyl carbonate.

[0074] The reaction temperature and reaction time in step (C1) can be appropriately adjusted depending on the types and amounts of raw materials used, the presence or absence of a catalyst, etc. The reaction temperature can be, for example, 0°C to 100°C, and preferably 20°C to 80°C. The reaction time can be, for example, 0.1 hours to 120 hours, and preferably 1 hour to 50 hours.

[0075] The extraction solvent used in step (D1) is not particularly limited as long as it can reprecipitate (extract) the modified carbonate prepared. Examples of the extraction solvent include ethanol, methanol, isopropanol, cyclohexane, n-hexane, and water.

[0076] In the step (D1), the method for separating the reprecipitated modified carbonate is not particularly limited, and examples thereof include filtration.

[0077] The drying method in step (E1) is not particularly limited, and known methods can be used. Examples of the drying method that can be used include vacuum drying, hot air drying, air drying, and freeze drying. The drying conditions, such as the drying temperature and drying time, used in the drying method are not particularly limited. The drying temperature can be −100° C. to 150° C., and preferably 20° C. to 120° C. The drying time can be, for example, 0.1 hours to 100 hours, and preferably 1 hour to 20 hours.

[0078] The solution process may include a step of washing the separated modified carbonate between steps (D1) and (E1). The washing method is not particularly limited, and examples include a method in which an appropriate washing solution is added to the separated modified carbonate, and then the modified carbonate is separated again by filtration or the like. The washing solution is not particularly limited, as long as it does not dissolve the modified carbonate and does not adversely affect the modified carbonate, and examples include ethanol, methanol, isopropanol, water, etc.

[0079] The melt process is a process in which a raw material polycarbonate is reacted with the compound (1A) and / or the compound (2A) in a solid state, and specifically, the process can be carried out, for example, by a method including the following steps (A2) to (D2):

[0080] (A2) A step of dissolving the compound (1A) and / or the compound (2A), and optionally a catalyst, in an appropriate solvent to prepare a solution A2.

[0081] (B2) A step of attaching the solution A2 prepared in the step (A2), or the compound (1) and / or the compound (2) directly to the surface of a solid raw material polycarbonate such as pellets.

[0082] (C2) A step of drying the solid starting polycarbonate to which Solution A2 has adhered obtained in Step (B2), and optionally removing the solvent, to prepare a mixture containing the starting polycarbonate, Compound (1A) and / or Compound (2A), and, optionally, the catalyst.

[0083] (D2) A step of melt-kneading the mixture prepared in step (C2) to react the raw polycarbonate with compound (1A) and / or compound (2A) to prepare the present modified carbonate.

[0084] The solvent used in step (A2) is not particularly limited as long as it can dissolve compound (1A) and / or compound (2A), and examples thereof include ethanol, methanol, isopropanol, toluene, tetrahydrofuran, dichloromethane, chloroform, and ethyl acetate. Among these solvents, dichloromethane and chloroform, which are good solvents for the raw polycarbonate, are preferably used as the solvent in step (A2) because they facilitate penetration of compound (1A) and / or compound (2A) into the solid raw polycarbonate. However, in this case, if the solubility of the solvent in step (A2) for the raw polycarbonate is too high, there is a risk that the solid raw polycarbonate will adhere to the reactor or the like. Therefore, it is preferable to use a small amount of a poor solvent for the raw polycarbonate, such as ethanol, methanol, or isopropanol, in addition to a good solvent for the raw polycarbonate.

[0085] The drying method in step (C2) is not particularly limited, and known methods can be used. Examples of the drying method that can be used include air drying, vacuum drying, and hot air drying. The drying conditions, such as the drying temperature and drying time, used in the drying method are not particularly limited as long as the solvent can be removed. The drying temperature can be 0°C to 150°C, and preferably 20°C to 120°C. The drying time can be, for example, 0.1 hours to 50 hours, and preferably 1 hour to 20 hours.

[0086] The temperature of the mixture during melt-kneading in the step (D2), i.e., the reaction temperature, may be 150° C. to 350° C., and preferably 180° C. to 300° C. The time for the melt-kneading, i.e., the reaction time, may be, for example, 10 seconds to 10 hours, and preferably 30 seconds to 1 hour.

[0087] [3. First Resin Composition] A resin composition according to one embodiment of the present invention (hereinafter referred to as the "first resin composition") comprises a raw material polycarbonate, a compound containing a structural unit represented by the following formula (1) and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by the following formula (2) and a group capable of reacting with a carbonate group to form a bond. -R-S-S-R- (1) (In formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom) -R-SH (2) (In formula (2), R is the same as R in formula (1)). In short, the first resin composition comprises a raw material polycarbonate, and compound (1A) and / or compound (2A). Regarding matters relating to the first resin composition, components common to the present modified polycarbonate and the present production method are described in [1. Modified polycarbonate] and [2. Method for producing modified polycarbonate] are incorporated herein by reference as appropriate.

[0088] <Use of the First Resin Composition> By performing appropriate treatment using the first resin composition, the transesterification reaction due to the nucleophilic attack described above can be initiated, thereby enabling the present production method to be carried out. In other words, the first resin composition can be used as a kit for carrying out the present production method to produce the present modified polycarbonate. Therefore, by using the first resin composition, the present modified polycarbonate, i.e., a modified polycarbonate that has excellent flowability during molding and does not reduce the physical properties such as strength, durability, and heat resistance of the resulting molded body, can be produced at low cost and easily.

[0089] The appropriate treatment is not particularly limited as long as it can initiate the transesterification reaction between the raw polycarbonate and compound (1A) and / or compound (2A) via the nucleophilic attack described above. Examples of the appropriate treatment include heat treatment, ultrasonic irradiation, microwave irradiation, electron beam irradiation, ultraviolet irradiation, and mechanochemical methods. The treatment conditions (treatment temperature, treatment time, etc.) for the appropriate treatment can be appropriately adjusted depending on the treatment method, the type and amount of raw materials used, and the presence or absence of a catalyst. When heat treatment is used as the appropriate treatment, the treatment temperature can be, for example, 0°C to 150°C, preferably 20°C to 100°C, and the treatment time can be, for example, 0.1 hours to 100 hours, preferably 1 hour to 50 hours.

[0090] <Configuration of the first resin composition> (Raw material polycarbonate) The raw material polycarbonate in the first resin composition is a polycarbonate having a lower content of the structural unit represented by the formula (1) than the modified polycarbonate produced by carrying out the present production method by subjecting the first resin composition to the appropriate treatment, or a polycarbonate that does not contain the structural unit represented by the formula (1). The raw material polycarbonate in the first resin composition is not particularly limited, and for example, the polycarbonates listed in the (raw material polycarbonate) column of the <Modification step> in [2. Method for producing modified polycarbonate] can be used.

[0091] (Content of Compound (1A) and Compound (2A)) In the first resin composition, the value represented by the following formula (3') is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and even more preferably 0.01 mol% or more. Furthermore, the value represented by the following mathematical formula (3') is preferably 30 mol % or less, more preferably 20 mol % or less, and even more preferably 10 mol % or less: [{A' + (B' / 2) + C'} / D'] x 100 (3') (In mathematical formula (3'), A' is the content (mol) of the compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond in the resin composition, B' is the content (mol) of the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond in the resin composition, C' is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition, and D' is the number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition).

[0092] By ensuring that the value represented by formula (3') is within the above-mentioned range, the present modified polycarbonate can be more suitably produced using the first resin composition, in which the proportion X of the structural unit represented by formula (1) is within the preferred range shown in the section [1. Modified Polycarbonate]. Furthermore, when the first resin composition contains a compound having multiple mercapto groups in one molecule, formula (3') can be appropriately corrected according to the amount added. When the proportion X of the structural unit represented by formula (1) is within the preferred range shown in the section [1. Modified Polycarbonate], the present modified polycarbonate has better melt flowability and is easier to handle during molding.

[0093] (Catalyst) The first resin composition may contain a catalyst. The description of the catalyst in the section [2. Method for producing modified polycarbonate] is incorporated herein by reference.

[0094] (Other Additives) The first resin composition may further contain other additives as components other than the raw polycarbonate, the compound (1A) and / or the compound (2A), and the catalyst, depending on the purpose. The other additives are not particularly limited as long as they do not impair the effects of the present invention, and examples thereof include flow improvers, antioxidants, reinforcing agents, thickeners, mold release agents, coupling agents, flame retardants, flame retardants, pigments, colorants, light diffusing agents, and fillers. The content of the other additives is not particularly limited as long as they do not impair the effects of the present invention, and is preferably, for example, in the range of 0 to 100 parts by weight in total, relative to 100 parts by weight of the total weight of the raw polycarbonate, the compound (1A) and / or the compound (2A), and the catalyst.

[0095] <Method for Producing First Resin Composition> The method for producing the first resin composition is not particularly limited, and may be, for example, a method in which the raw material polycarbonate, the compound (1A) and / or the compound (2A), optionally the catalyst, and optionally the other additives are mixed using a known method.

[0096] 4. Second Resin Composition A resin composition according to another embodiment of the present invention (hereinafter referred to as the "second resin composition") contains the present modified polycarbonate and an unmodified polycarbonate.

[0097] Regarding matters relating to the second resin composition, for components common to the present modified polycarbonate, the present manufacturing method, and the first resin composition, the matters described in the columns [1. Modified polycarbonate], [2. Manufacturing method for modified polycarbonate], and [3. First resin composition] are appropriately cited.

[0098] The second resin composition contains the modified polycarbonate. Thus, like the modified polycarbonate, the second resin composition has excellent flowability during molding, and when molded, molded articles can be produced at low cost and easily without deteriorating the physical properties of the molded article, such as strength, durability, and heat resistance.

[0099] <Configuration of the second resin composition> (Unmodified polycarbonate) The unmodified polycarbonate in the second resin composition is an unmodified polycarbonate, and like the raw polycarbonate, it is a polycarbonate having a lower content of the structural unit represented by formula (1) than the modified polycarbonate in the second resin composition. The unmodified polycarbonate may be a polycarbonate that does not contain the structural unit represented by formula (1) and may be a polycarbonate that does not have an S-S bond in the main chain. As the unmodified polycarbonate, for example, the polycarbonates listed in the (raw polycarbonate) section of the <Modification step> in [2. Method for producing modified polycarbonate] can be used. The unmodified polycarbonate may be the same or different from the raw polycarbonate used to obtain the modified polycarbonate in the second resin composition.

[0100] (Proportion Y of structural units represented by formula (1)) Hereinafter, "the proportion of the total number of moles of structural units other than the structural units represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate relative to the total number of moles of structural units other than the structural units represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate in the second resin composition" is referred to as "proportion Y of the number of moles of structural units represented by formula (1)". Note that "the total number of moles of structural units other than the structural units represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate" means the total number of moles of structural units other than the structural units represented by formula (1) in the main chain of the modified polycarbonate and the structural units other than the structural units represented by formula (1) in the main chain of the unmodified polycarbonate. Furthermore, "the total number of moles of the structural units represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate" means the total number of moles of the structural units represented by formula (1) in the main chain of the modified polycarbonate and the structural units represented by formula (1) in the main chain of the unmodified polycarbonate.

[0101] The molar ratio Y of the structural unit represented by the formula (1) is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and even more preferably 0.01 mol% or more. When the molar ratio Y of the structural unit represented by the formula (1) is 0.001 mol% or more, the modified polycarbonate in the second resin composition can be decomposed into polycarbonates with lower molecular weights by heating during molding. As a result, the second resin composition, like the present modified polycarbonate, becomes a melt with better fluidity during molding, containing more low molecular weight polycarbonates.

[0102] In the second resin composition, the molar ratio Y of the structural unit represented by the formula (1) is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less. When the molar ratio Y of the structural unit represented by the formula (1) is 30 mol% or less, as with the present modified polycarbonate, the melt fluidity of the second resin composition is excessively increased by heating during molding, which can prevent a decrease in handleability during molding.

[0103] (Other additives) The second resin composition may further contain other additives depending on the purpose as components other than the modified polycarbonate and the unmodified polycarbonate. The other additives are not particularly limited as long as the effects of the present invention are not lost, and examples thereof include the additives listed in (Other additives) of <Configuration of the first resin composition> in [3. First resin composition]. In addition, the content of other additives in the second resin composition is not particularly limited as long as the effects of the present invention are not lost, and for example, the preferred range of the content of other additives described in (Other additives) of <Configuration of the first resin composition> in [3. First resin composition] can be adopted.

[0104] <Method for producing second resin composition> The method for producing the second resin composition is not particularly limited. Examples of the method for producing the second resin composition include a method of mixing the present modified polycarbonate and the unmodified polycarbonate using a known method. The method for producing the second resin composition may include a step of preparing the present modified polycarbonate. In the step of preparing the present modified polycarbonate, the method for preparing the present modified polycarbonate is not particularly limited, and examples thereof include preparing the present modified polycarbonate using the present production method. In the method for producing the second resin composition, the mixing ratio of the present modified polycarbonate and the unmodified polycarbonate is not particularly limited. As the mixing ratio of the present modified polycarbonate and the unmodified polycarbonate, it is preferable to adopt a mixing ratio such that the ratio Y of the number of moles of the structural unit represented by the formula (1) in the obtained second resin composition is within the above-mentioned preferred range.

[0105] <Uses of the present resin composition> When the first resin composition is subjected to a molding process, the first resin composition is generally heated and molten during the process. At that time, the first resin composition changes into a composition containing the present modified polycarbonate. Here, as described above, the present modified polycarbonate has excellent melt fluidity, so the first resin composition also has excellent fluidity during molding. Furthermore, since the second resin composition also contains the present modified polycarbonate, it has excellent fluidity during molding, similar to the present modified polycarbonate. Therefore, the first resin composition and the second resin composition (hereinafter collectively referred to as the present resin composition) can also be suitably molded, similar to the present modified polycarbonate. Therefore, by molding the present resin composition, molded articles with excellent moldability can be suitably produced. The molding method for molding the present resin composition is not particularly limited, and general molding methods can be used. Examples of the molding method include [1. Examples of suitable molding methods include those listed in the <Applications of the Modified Polycarbonate> section of [1. Modified Polycarbonate]. The molded articles obtained by molding the resin composition have excellent physical properties such as strength, durability, and heat resistance, similar to those of the molded articles obtained by molding the modified polycarbonate. Therefore, the molded articles obtained by molding the resin composition can be suitably used in the various applications listed in the <Applications of the Modified Polycarbonate> section of [1. Modified Polycarbonate].

[0106] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0107] That is, one embodiment of the present invention encompasses the following inventions. <1> A modified polycarbonate having, in its main chain, a structural unit represented by the following formula (1): -R-S-S-R- (1) (In formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom.) <2> The modified polycarbonate according to <1>, in which the ratio of the number of moles of the structural unit represented by formula (1) to the number of moles of structural units other than the structural unit represented by formula (1) in the main chain is 0.001 mol % or more and 30 mol % or less. <3> The modified polycarbonate according to <1> or <2>, in which each R is independently one or more groups selected from the group consisting of a methylene group, an ethylene group, a propylene group, a 1-aminoethylene group, a 1-(carbonylamino)ethylene group, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a thiazole ring, and a phenylene group. <4> A method for producing the modified polycarbonate according to any one of <1> to <3>, comprising a modifying step of reacting a raw material polycarbonate with a compound containing a structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by formula (2) below and a group capable of reacting with a carbonate group to form a bond: -R-SH (2) (In formula (2), R is the same as R in formula (1)). <5> The method for producing a modified polycarbonate according to <4>, wherein in the modifying step, the value represented by formula (3) below is 0.001 mol % or more and 30 mol % or less.

[0108] [{A+(B / 2)+C} / D]×100 (3) (In formula (3), A is the amount (mol) of the compound used that contains the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond, B is the amount (mol) of the compound used that contains the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond, C is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate, and D is the number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate.) <6> The compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of dimethyl-3,3'-dithiodipropionate, L-cystine dimethyl ether dihydrochloride, bis(2-hydroxyethyl)disulfide, cystine, oxidized glutathione, bis(4-hydroxyphenyl)disulfide, 3,3'-dihydroxydiphenyl disulfide, 4,4'-dithiodianiline, 3,3'-dithiodipropionic acid, cystamine, 4,4'-dithiodibutyric acid, 2,2'-dithiodibenzoic acid, 6,6'-dithiodinicotinic acid, dithiodiglycolic acid, and bis(4-benzenecarboxylic acid)disulfide, The method for producing a modified polycarbonate according to <4> or <5>, wherein the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of methyl 3-mercaptopropanoate, L-cysteine ​​ethyl ester hydrochloride, 2-mercaptoethanol, cysteine, acetylcysteine, p-mercaptophenol, thioglycolic acid, 4-mercaptoaniline, 4-mercaptobutyric acid, and p-mercaptobenzoic acid. <7> A resin composition comprising a raw material polycarbonate, and a compound containing a structural unit represented by formula (1) below and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by formula (2) below and a group capable of reacting with a carbonate group to form a bond.-R-S-S-R- (1) (In formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom) -R-SH (2) (In formula (2), R is the same as R in formula (1) above.) <8> The resin composition according to <7>, wherein the value represented by the following formula (3') is 0.001 mol % or more and 30 mol % or less.

[0109] [{A'+(B' / 2)+C'} / D']×100 (3') (In formula (3'), A' is the content (mol) of the compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond in the resin composition, B' is the content (mol) of the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond in the resin composition, C' is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition, and D' is the number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition). <9> The compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of dimethyl-3,3'-dithiodipropionate, L-cystine dimethyl ether dihydrochloride, bis(2-hydroxyethyl)disulfide, cystine, oxidized glutathione, bis(4-hydroxyphenyl)disulfide, 3,3'-dihydroxyphenyl disulfide, 4,4'-dithiodianiline, 3,3'-dithiodipropionic acid, cystamine, 4,4'-dithiodibutyric acid, 2,2'-dithiodibenzoic acid, 6,6'-dithiodinicotinic acid, dithiodiglycolic acid, and bis(4-benzenecarboxylic acid)disulfide, The resin composition according to <7> or <8>, wherein the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of methyl 3-mercaptopropanoate, L-cysteine ​​ethyl ester hydrochloride, 2-mercaptoethanol, cysteine, acetylcysteine, p-mercaptophenol, thioglycolic acid, 4-mercaptoaniline, 4-mercaptobutyric acid, and p-mercaptobenzoic acid.<10> A resin composition comprising the modified polycarbonate according to any one of <1> to <3> and an unmodified polycarbonate.<11> The resin composition according to <10>, wherein the ratio of the total number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate to the total number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate is 0.001 mol% or more and 30 mol% or less.

[0110] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0111] [Evaluation Method] <GPC (Gel Permeation Chromatography) Analysis> The comparative polycarbonate described in Comparative Example 1 and the modified polycarbonates (1), (6) to (9), and (18) to (20) described in Examples 1, 6 to 9, and 18 to 20 were each subjected to GPC analysis using a high-speed GPC device (manufacturer: Tosoh Technosystems Corporation, product name: HLC-8320GPC, column: TSK-GEL SuperHM-N, eluent: chloroform) to measure the number average molecular weight (Mn) and weight average molecular weight (Mw).

[0112] <TG (thermogravimetric) analysis> The modified polycarbonates (1) and (6) described in Examples 1 and 6 were each subjected to TG analysis using a simultaneous thermogravimetric and differential thermal analyzer (manufactured by Hitachi High-Tech Science Corporation, product name: STA7200) under the measurement conditions shown below, and the temperature at which a 5% weight loss was observed (T ｄ５ Measurement conditions: Temperature range: 25 to 300°C, heating rate: 10°C / min.

[0113] <DSC (Differential Scanning Calorimeter) Analysis> For each of the comparative polycarbonate described in Comparative Example 1 and the modified polycarbonates (1) and (3) described in Examples 1 and 3, DSC analysis was performed using a high-sensitivity differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, product name: DSC7000X) under the measurement conditions shown below to obtain DSC curves. Furthermore, in the DSC curve, the peak temperature (Tv) corresponding to the cleavage of the S—S bond was measured. Furthermore, in the DSC curve, the peak temperature (Tm) corresponding to the melting point was measured. Measurement conditions: Temperature range: 25 to 250°C, heating rate: 10°C / min.

[0114] <MFR (Melt Flow Rate) Measurement> For the comparative polycarbonate described in Comparative Example 1, and the modified polycarbonates (1), (3) to (12), (18) to (21), and (23) described in Examples 1 to 23, and the resin compositions (2), (13) to (17), and (22), respectively, the MFR was measured using a melt flow rate tester (manufacturer: Yasuda Seiki Seisakusho Co., Ltd., product name: No. 120-FWP) under the following measurement conditions: Measurement conditions: temperature: 260°C, preheating time: 180 seconds, load: 1.525 kg.

[0115] Comparative Example 1 A commercially available polycarbonate (Iupilon H-3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was prepared as a comparative polycarbonate. The comparative polycarbonate was a polycarbonate that did not contain the structural unit represented by formula (1).

[0116] Example 1 Polycarbonate (Iupilon H-3000, manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the raw polycarbonate. 25.43 g of the raw polycarbonate (100.0 mmol of monomer unit) was dissolved in 150 g of dichloromethane to obtain a raw polycarbonate solution. 1.317 g (7.257 mmol) of bis(2-hydroxyethyl) disulfide (85% purity, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 0.111 g (0.372 mmol) of titanium tetraisopropoxide (95% purity, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to the obtained raw polycarbonate solution to obtain a reaction solution. The reaction solution was then stirred at room temperature for 5 days. The stirred reaction solution was slowly added to 500 mL of ethanol to obtain a mixed solution. At this time, a white solid was formed in the mixed solution. The formed white solid was separated from the mixed solution by filtration. The separated white solid was washed with 100 mL of ethanol and then washed again with another 100 mL of ethanol. The washing was performed by adding ethanol to the separated white solid to prepare a dispersion, and then filtering the dispersion to separate the washed white solid from the dispersion. The white solid after the second washing was vacuum dried at 80°C to obtain 25.41 g of modified polycarbonate (white solid). The resulting modified polycarbonate was designated modified polycarbonate (1). The theoretical amount of disulfide bonds introduced into modified polycarbonate (1), i.e., the theoretical amount of the structural unit represented by formula (1), was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the monomer unit (structural unit derived from the monomer) of the raw polycarbonate in modified polycarbonate (1) was calculated to be 7.256 mol%. In addition, the weight loss of the modified polycarbonate (1) at 300°C in TG analysis was 2.9%.

[0117] In Example 1, the structural unit represented by the formula (1) is introduced into the raw polycarbonate, and the reaction formula by which the modified polycarbonate (1) is produced is shown below. In the following reaction formula, the chemical formula on the upper left represents the raw polycarbonate, the chemical formula on the upper right represents bis(2-hydroxyethyl)disulfide, which corresponds to the compound (1A), and the chemical formula on the bottom represents the modified polycarbonate. In Examples 3 to 12 described below, modified polycarbonates are also produced by the same reaction as in Example 1. n represents the number of repeating units.

[0118] Example 2 0.5314 g of the modified polycarbonate (1) obtained in Example 1 was mixed with 5.2193 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is designated as resin composition (2). As in Example 1, the amount (theoretical value) of the structural unit represented by formula (1) in the modified polycarbonate (1) in resin composition (2) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (2) was calculated to be 0.670 mol%. Note that the number of moles of the structural unit derived from the monomer of the raw polycarbonate in Example 2 is the sum of the number of moles of the structural unit derived from the monomer in both the raw polycarbonate used in the production of the modified polycarbonate (1) and the raw polycarbonate used in Example 2. Similarly, in Examples 13 to 17, the number of moles of structural units derived from the monomers of the raw polycarbonate is the total number of moles of structural units derived from the monomers in both the raw polycarbonate used in the production of the modified polycarbonate and the raw polycarbonate used.

[0119] [Example 3] A modified polycarbonate was obtained in the same manner as in Example 1, except for the following changes. The obtained modified polycarbonate was designated as Modified Polycarbonate (3): the amount of raw polycarbonate used was changed to 24.99 g, the amount of bis(2-hydroxyethyl) disulfide used was changed to 14.7 mg, and the amount of titanium tetraisopropoxide used was changed to 3.2 mg.

[0120] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (3) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (3) was calculated to be 0.082 mol%.

[0121] [Example 4] A modified polycarbonate was obtained in the same manner as in Example 1, except for the following: The obtained modified polycarbonate was designated as modified polycarbonate (4). The amount of raw polycarbonate used was changed to 25.84 g, the amount of bis(2-hydroxyethyl) disulfide used was changed to 15.0 mg, and the catalyst titanium tetraisopropoxide was not used.

[0122] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (4) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (4) was calculated to be 0.082 mol%.

[0123] [Example 5] A modified polycarbonate was obtained in the same manner as in Example 1, except for the following: The obtained modified polycarbonate was designated as modified polycarbonate (5). The amount of raw polycarbonate used was changed to 50.04 g, the amount of bis(2-hydroxyethyl) disulfide used was changed to 6.9 mg, the amount of titanium tetraisopropoxide used was changed to 0.3 mg, and the stirring time for the reaction solution was changed to 10 days.

[0124] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (5) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (5) was calculated to be 0.019 mol%.

[0125] [Example 6] A modified polycarbonate was obtained in the same manner as in Example 1, except for the following changes. The obtained modified polycarbonate was designated as Modified Polycarbonate (6): the amount of bis(2-hydroxyethyl) disulfide used was changed to 2.616 g, and the amount of titanium tetraisopropoxide used was changed to 0.105 g.

[0126] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (6) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (6) was calculated to be 14.414 mol%.

[0127] Example 7 Polycarbonate (Iupilon H-3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the raw polycarbonate. The raw polycarbonate was purchased in pellet form. The total weight of the pellets was 50.8561 g. Furthermore, 7.9 mg of bis(2-hydroxyethyl) disulfide and 2.3 mg of titanium tetraisopropoxide were dissolved in 2 mL of ethanol to obtain a solution. The obtained solution was evenly applied to the surface of pellets made of the raw polycarbonate, and the pellets were then air-dried to volatilize the ethanol. All of the pellets after the ethanol had volatilized were melt-kneaded in a twin-screw extruder at 240°C to obtain strands made of modified polycarbonate. The obtained strands were cut to obtain pellets of modified polycarbonate. The obtained pellets of modified polycarbonate were designated modified polycarbonate (7).

[0128] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (7) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (7) was calculated to be 0.022 mol%.

[0129] [Example 8] A modified polycarbonate was obtained in the same manner as in Example 7, except for the following: The obtained modified polycarbonate was designated as modified polycarbonate (8). The amount of raw polycarbonate used was changed to 50.9841 g, the amount of bis(2-hydroxyethyl) disulfide used was changed to 6.5 mg, and the catalyst titanium tetraisopropoxide was not used.

[0130] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (8) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (8) was calculated to be 0.018 mol%.

[0131] Example 9 Polycarbonate (Iupilon H-3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the raw polycarbonate. The raw polycarbonate was purchased in pellet form. The total weight of the pellets was 25.4400 g. Additionally, 6.8 mg of bis(2-hydroxyethyl) disulfide and 2.4 mg of titanium tetraisopropoxide were dissolved in 1 mL of ethanol to obtain a solution. The obtained solution was evenly applied to the surface of pellets made of the raw polycarbonate, and the pellets were then air-dried to volatilize the ethanol. Next, all of the pellets after the ethanol had volatilized were heated at 80°C for 3 hours in a sealed state inside a mayonnaise bottle to obtain modified polycarbonate pellets. The obtained modified polycarbonate pellets are designated modified polycarbonate (9). The heating in the sealed state inside the mayonnaise bottle was intended to cause a reaction between the raw polycarbonate and bis(2-hydroxyethyl) disulfide on the surface of the pellets, thereby introducing a constitutional unit containing a disulfide group and represented by formula (1) into the raw polycarbonate.

[0132] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (9) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (9) was calculated to be 0.037 mol%.

[0133] [Example 10] A modified polycarbonate was obtained in the same manner as in Example 9, except for the following: The obtained modified polycarbonate was designated as modified polycarbonate (10). The amount of raw polycarbonate used was changed to 25.4509 g, the amount of bis(2-hydroxyethyl) disulfide used was changed to 7.7 mg, and the catalyst titanium tetraisopropoxide was not used.

[0134] The amount (theoretical value) of the structural unit represented by formula (1) introduced into the modified polycarbonate (10) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in the modified polycarbonate (10) was calculated to be 0.042 mol%.

[0135] Example 11 A modified polycarbonate was obtained using the same method as in Example 9, except for the following changes. The resulting modified polycarbonate was designated modified polycarbonate (11). The amount of raw polycarbonate used was changed to 203.2044 g; the amount of bis(2-hydroxyethyl)disulfide used was changed to 2.1010 g; the catalyst titanium tetraisopropoxide was not used; and the solvent ethanol (1 mL) was replaced with dichloromethane (17.0 g). Because bis(2-hydroxyethyl)disulfide does not dissolve in dichloromethane, it was used in a suspended state after thorough shaking.

[0136] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (11) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (11) was calculated to be 1.445 mol%.

[0137] [Example 12] A modified polycarbonate was obtained in the same manner as in Example 11, except for the following: The amount of raw polycarbonate used was changed to 203.0781 g, and the amount of bis(2-hydroxyethyl) disulfide used was changed to 10.5004 g.

[0138] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (12) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (12) was calculated to be 7.245 mol%.

[0139] [Example 13] 0.1035 g of the modified polycarbonate (11) obtained in Example 11 was mixed with 4.9019 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is designated as resin composition (13). The amount (theoretical value) of the structural unit represented by formula (1) in resin composition (13) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (13) was calculated to be 0.030 mol%.

[0140] [Example 14] 1.0212 g of the modified polycarbonate (11) obtained in Example 11 was mixed with 4.0141 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is designated as resin composition (14). The amount (theoretical value) of the structural unit represented by formula (1) in resin composition (14) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (14) was calculated to be 0.294 mol%.

[0141] [Example 15] 0.1078 g of the modified polycarbonate (12) obtained in Example 12 was mixed with 4.9063 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is designated as resin composition (15). The amount (theoretical value) of the structural unit represented by formula (1) in resin composition (15) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (15) was calculated to be 0.156 mol%.

[0142] [Example 16] 0.5132 g of the modified polycarbonate (12) obtained in Example 12 was mixed with 4.0141 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is designated as resin composition (16). The amount (theoretical value) of the structural unit represented by formula (1) in resin composition (16) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (16) was calculated to be 0.821 mol%.

[0143] [Example 17] 0.9940 g of the modified polycarbonate (12) obtained in Example 12 was mixed with 3.9979 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is referred to as resin composition (17). The amount (theoretical value) of the structural unit represented by the formula (1) in resin composition (17) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by the formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (17) was calculated to be 1.443 mol%.

[0144] Example 18 A modified polycarbonate was obtained in the same manner as in Example 11, except for the following: The obtained modified polycarbonate was designated modified polycarbonate (18). 20.0142 g of modified polycarbonate (9) obtained in Example 9 was used instead of the raw polycarbonate; the amount of bis(2-hydroxyethyl) disulfide used was changed to 0.1308 g; and 0.0300 g of titanium tetraisopropoxide was used as the catalyst.

[0145] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (18) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (18) was calculated to be 0.953 mol%.

[0146] Example 19 A modified polycarbonate was obtained in the same manner as in Example 18, except for the following: The obtained modified polycarbonate was designated modified polycarbonate (19). 20.1422 g of modified polycarbonate (10) obtained in Example 10 was used instead of modified polycarbonate (9); the amount of bis(2-hydroxyethyl) disulfide used was changed to 0.1312 g; and titanium tetraisopropoxide was not used as a catalyst.

[0147] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (19) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (19) was calculated to be 0.961 mol%.

[0148] Example 20 Polycarbonate (Iupilon H-3000 manufactured by Mitsubishi Engineering-Plastics Corporation) was used as the raw polycarbonate. The raw polycarbonate was purchased in pellet form. The total weight of the pellets was 19.4683 g. 137.5 mg of bis(2-hydroxyethyl) disulfide was evenly adhered to the surface of the pellets made of the raw polycarbonate, and the pellets were then heated at 80°C for 3 hours while sealed inside a mayonnaise bottle. The lid was then removed and the bottle was heated in an open state at 100°C for 5 hours to obtain modified polycarbonate pellets. The resulting modified polycarbonate pellets were designated modified polycarbonate (20).

[0149] The amount (theoretical value) of the structural unit represented by formula (1) introduced into the modified polycarbonate (20) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in the modified polycarbonate (20) was calculated to be 0.990 mol%.

[0150] Example 21 A modified polycarbonate was obtained in the same manner as in Example 1, except for the following changes. The obtained modified polycarbonate is designated as modified polycarbonate (21): The amount of raw polycarbonate used was changed to 25.12 g, bis(4-hydroxyphenyl) disulfide was used instead of bis(2-hydroxyethyl) disulfide, and the amount used was changed to 240.0 mg, and the amount of titanium tetraisopropoxide used was changed to 10.0 mg.

[0151] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (21) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (21) was calculated to be 0.952 mol%.

[0152] In Example 21, the structural unit represented by formula (1) was introduced into the starting polycarbonate to produce the modified polycarbonate (1), as shown in the reaction formula below. In the following reaction formula, the upper left chemical formula represents the starting polycarbonate, the upper right chemical formula represents bis(4-hydroxyphenyl)disulfide, which corresponds to compound (1A), and the lower chemical formula represents the modified polycarbonate. n and m represent the number of repeating units.

[0153] [Example 22] 1.243 g of the modified polycarbonate (21) obtained in Example 21 was mixed with 5.5252 g of the same polycarbonate H-3000 as the raw polycarbonate used in Example 1 to obtain a resin composition corresponding to the second resin composition. The resulting resin composition is referred to as resin composition (22). As in Example 1, the amount (theoretical value) of the structural unit represented by the formula (1) in the modified polycarbonate (1) in resin composition (22) was calculated based on the amount of raw material used. As a result, the ratio of the structural unit represented by the formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in resin composition (22) was calculated to be 0.034 mol%. The number of moles of structural units derived from the monomers in the starting polycarbonate in Example 22 is the total number of moles of structural units derived from the monomers in both the starting polycarbonate used in the production of the modified polycarbonate (21) and the starting polycarbonate used in Example 22.

[0154] [Example 23] A modified polycarbonate was obtained in the same manner as in Example 21, except for the following changes: The amount of raw polycarbonate used was changed to 23.46 g, the amount of bis(4-hydroxyphenyl) disulfide used was changed to 0.525 g, and the amount of titanium tetraisopropoxide used was changed to 3.0 mg.

[0155] The amount (theoretical value) of the structural unit represented by formula (1) introduced into modified polycarbonate (23) was calculated based on the amount of raw material used, as in Example 1. As a result, the ratio of the structural unit represented by formula (1) to the number of moles of the structural unit derived from the monomer of the raw polycarbonate in modified polycarbonate (23) was calculated to be 2.227 mol%.

[0156] [Results] The physical properties of the comparative polycarbonate described in Comparative Example 1, the modified polycarbonates (1), (3) to (12), (18) to (21), and (23) described in Examples 1 to 23, and the resin compositions (2), (13) to (17), and (22) were measured using the methods described above. The measured physical properties and the ratio of the structural units represented by formula (1) to the number of moles of structural units derived from the monomers of the raw polycarbonate, calculated based on the amount of raw materials used, are shown in Table 1 below. In Table 1, the ratio of the structural units represented by formula (1) to the number of moles of structural units derived from the monomers of the raw polycarbonate, is referred to as the "ratio of structural units represented by formula (1)." In addition, the "ratio of structural units represented by formula (1)" in the modified polycarbonates (1), (3) to (12), (18) to (21), and (23) corresponds to the "ratio X of the number of moles of structural units represented by formula (1)." Furthermore, in resin compositions (2), (13) to (17), and (22), the unmodified polycarbonate does not have the structural unit represented by formula (1). Therefore, the "proportion of the structural unit represented by formula (1)" in resin compositions (2), (13) to (17), and (22) corresponds to the "proportion Y of the number of moles of the structural unit represented by formula (1)."

[0157] As shown in Table 1, the modified polycarbonates (1), (3) to (12), (18) to (21), and (23) described in Examples 1, 3 to 12, 18 to 21, and 23 have higher MFR and improved melt fluidity than the comparative polycarbonate described in Comparative Example 1, i.e., the raw polycarbonate. Furthermore, GPC analysis showed that the Mn and Mw of the modified polycarbonates (1), (6) to (9), and (18) to (20) were both almost identical to the Mn and Mw of the raw polycarbonate. Furthermore, the resin compositions (2), (13) to (17), and (22) described in Examples 2, 13 to 17, and 22 have higher MFR and improved melt fluidity than the comparative polycarbonate described in Comparative Example 1, i.e., the unmodified polycarbonate.

[0158] Furthermore, as a result of DSC analysis, the comparative polycarbonate (raw polycarbonate) showed only one endothermic peak (peak temperature: Tm = 230 ° C.) corresponding to the melting point, whereas the modified polycarbonates (1) and (3) showed a new endothermic peak (peak temperature: Tv = 181 ° C.) in addition to the endothermic peak (peak temperature: Tm = 222 ° C.) corresponding to the melting point. In addition, the DSC curves obtained as a result of DSC analysis of the comparative polycarbonate (raw polycarbonate), modified polycarbonate (1), and modified polycarbonate (3) are shown in Figures 1 to 3. As mentioned above, the modified polycarbonate (1) and modified polycarbonate (3) show the new endothermic peak that is not observed in the DSC curve of the raw polycarbonate.

[0159] The new endothermic peak is thought to correspond to energy absorption due to cleavage of the S-S bond in the introduced structural unit represented by formula (1). Therefore, in modified polycarbonates (1), (3) to (12), (18) to (21), and (23), it was found that the structural unit represented by formula (1) was introduced into the raw polycarbonate. Therefore, modified polycarbonates (1), (3) to (12), (18) to (21), and (23) correspond to the present modified polycarbonate. Furthermore, in Examples 1, 3 to 12, 18 to (21), and (23), the present resin composition was used to carry out the present production method, and the present modified polycarbonate was produced. Furthermore, resin compositions (2), (13) to (17) and (22) correspond to the present modified polycarbonate, and therefore contain the modified polycarbonate (1), (11), (12) or (21). Therefore, they correspond to the second resin composition.

[0160] 2 and 3, the peak intensity of the new endothermic peak in the DSC curve of modified polycarbonate (3) is much smaller than the peak intensity of the new endothermic peak in the DSC curve of modified polycarbonate (1). This reflects the fact that the proportion (introduced amount) of the structural unit represented by formula (1) in modified polycarbonate (3) is lower than in modified polycarbonate (1). Furthermore, in Example 3, the amount of bis(2-hydroxyethyl) disulfide, which is a compound (compound (1A)) having the structural unit represented by formula (1), used is smaller than in Example 1. This shows that there is a correlation between the amount of compound (1A) used and the proportion of the structural unit represented by formula (1) in the modified polycarbonate.

[0161] In addition, the modified polycarbonates (1) and (6) exhibited the following T ｄ５ It was shown that the temperature was sufficiently high and the heat resistance was excellent.

[0162] From the above, it has been found that the present modified polycarbonate has excellent fluidity during molding, does not reduce the physical properties such as strength, durability, and heat resistance of the resulting molded body, and can be produced at low cost and easily. It has also been found that the present modified polycarbonate can be produced by using the first resin composition. Furthermore, it has been found that the second resin composition, like the present modified polycarbonate, has excellent fluidity during molding, and when molded, does not reduce the physical properties such as strength, durability, and heat resistance of the molded body produced, and can produce a molded body at low cost and easily.

[0163] This modified polycarbonate has the property of not reducing the strength, durability, heat resistance, and other physical properties of the molded article, and also has excellent melt fluidity. Therefore, this modified polycarbonate can be used to mold large, thin-walled, and complex-shaped molded articles, and is suitable for a wide range of applications, including electrical, electronic, and office equipment, optical components, precision machinery, automobiles, security and medical applications, building materials, and miscellaneous goods.

Claims

1. A modified polycarbonate having in its main chain a structural unit represented by the following formula (1): -R-S-S-R- (1) (In formula (1), each R is independently a divalent aliphatic hydrocarbon group which may contain a heteroatom, or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom.) 2. The modified polycarbonate according to claim 1, wherein the ratio of the number of moles of the structural unit represented by formula (1) to the number of moles of structural units other than the structural unit represented by formula (1) in the main chain is 0.001 mol % or more and 30 mol % or less.

3. The modified polycarbonate according to claim 1, wherein each R is independently one or more groups selected from the group consisting of a methylene group, an ethylene group, a propylene group, a 1-aminoethylene group, a 1-(carbonylamino)ethylene group, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a thiazole ring, and a phenylene group.

4. A method for producing the modified polycarbonate according to claim 1, comprising a modification step of reacting a raw material polycarbonate with a compound containing a structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by formula (2) below and a group capable of reacting with a carbonate group to form a bond: -R-SH (2) (in formula (2), R is the same as R in formula (1) above.) 5. The method for producing a modified polycarbonate according to claim 4, wherein in the modification step, the value represented by the following formula (3) is 0.001 mol % or more and 30 mol % or less: [{A + (B / 2) + C} / D] x 100 (3) (In formula (3), A is the amount (mol) of the compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond, B is the amount (mol) of the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond, C is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate, and D is the number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate).

6. The compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of dimethyl-3,3'-dithiodipropionate, L-cystine dimethyl ether dihydrochloride, bis(2-hydroxyethyl)disulfide, cystine, oxidized glutathione, bis(4-hydroxyphenyl)disulfide, 3,3'-dihydroxydiphenyl disulfide, 4,4'-dithiodianiline, 3,3'-dithiodipropionic acid, cystamine, 4,4'-dithiodibutyric acid, 2,2'-dithiodibenzoic acid, 6,6'-dithiodinicotinic acid, dithiodiglycolic acid, and bis(4-benzenecarboxylic acid)disulfide; The compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of methyl 3-mercaptopropanoate, L-cysteine ​​ethyl ester hydrochloride, 2-mercaptoethanol, cysteine, acetylcysteine, p-mercaptophenol, thioglycolic acid, 4-mercaptoaniline, 4-mercaptobutyric acid, and p-mercaptobenzoic acid. The method for producing a modified polycarbonate according to claim 4 or 5.

7. A resin composition comprising a raw material polycarbonate, and a compound containing a structural unit represented by the following formula (1) and a group capable of reacting with a carbonate group to form a bond, and / or a compound containing a structural unit represented by the following formula (2) and a group capable of reacting with a carbonate group to form a bond: -R-S-S-R- (1) (In formula (1), R is each independently a divalent aliphatic hydrocarbon group which may contain a heteroatom, or a monocyclic divalent aromatic hydrocarbon group which may contain a heteroatom) -R-SH (2) (In formula (2), R is the same as R in formula (1) above.) 8. The resin composition according to claim 7, wherein the value represented by the following formula (3') is 0.001 mol % or more and 30 mol % or less: [{A'+(B' / 2)+C'} / D']×100 (3') (In formula (3'), A' is the content (moles) of the compound containing the structural unit represented by formula (1) and a group capable of reacting with a carbonate group to form a bond in the resin composition, B' is the content (moles) of the compound containing the structural unit represented by formula (2) and a group capable of reacting with a carbonate group to form a bond in the resin composition, C' is the number of moles of the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition, and D' is the number of moles of the structural unit other than the structural unit represented by formula (1) in the main chain of the raw material polycarbonate in the resin composition).

9. The compound containing the structural unit represented by the formula (1) and a group capable of reacting with a carbonate group to form a bond is one or more selected from the group consisting of dimethyl-3,3'-dithiodipropionate, L-cystine dimethyl ether dihydrochloride, bis(2-hydroxyethyl)disulfide, cystine, oxidized glutathione, bis(4-hydroxyphenyl)disulfide, 3,3'-dihydroxyphenyl disulfide, 4,4'-dithiodianiline, 3,3'-dithiodipropionic acid, cystamine, 4,4'-dithiodibutyric acid, 2,2'-dithiodibenzoic acid, 6,6'-dithiodinicotinic acid, dithiodiglycolic acid, and bis(4-benzenecarboxylic acid)disulfide; The compound containing the structural unit represented by the formula (2) and a group capable of reacting with a carbonate group to form a bond is at least one selected from the group consisting of methyl 3-mercaptopropanoate, L-cysteine ​​ethyl ester hydrochloride, 2-mercaptoethanol, cysteine, acetylcysteine, p-mercaptophenol, thioglycolic acid, 4-mercaptoaniline, 4-mercaptobutyric acid, and p-mercaptobenzoic acid. The resin composition according to claim 7 or 8.

10. A resin composition comprising the modified polycarbonate according to any one of claims 1 to 3 and an unmodified polycarbonate.

11. The resin composition according to claim 10, wherein the ratio of the total number of moles of structural units represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate to the total number of moles of structural units other than the structural unit represented by formula (1) in the main chain of the modified polycarbonate and the main chain of the unmodified polycarbonate is 0.001 mol % or more and 30 mol % or less.

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