Polyester resin composition, molded article, and production method therefor

Abstract

Provided are a resin composition and a molded article which are less apt to generate isocyanate gas and which contain few foreign particles and hence have better surface appearance.　The resin composition comprises a polyester resin (A) and one or more carbodiimide compounds, wherein the carbodiimide compounds include a carbodiimide compound (B) represented by general formula (1). When the surface of a molded article comprising the resin composition is examined with an optical microscope, the number of observed foreign particles each having an area of 100 μm2 or larger is less than 10 per 100 cm2.

Description

Polyester resin composition, molded article, and method for producing the same

[0001] The present disclosure relates to a polyester resin composition, a molded article, and a method for producing the same.

[0002] Polyester resins such as polybutylene terephthalate (hereinafter referred to as PBT) are prone to hydrolysis due to the presence of ester groups in their molecular structure, and improvements in hydrolysis resistance using additives have been investigated. In particular, it is known that adding a carbodiimide compound to PBT can improve hydrolysis resistance, but this has the problem of generating toxic isocyanates when heated.

[0003] International Publication No. 2013 / 146625 Japanese Patent Application Laid-Open No. 2020-176167

[0004] Using a cyclic carbodiimide as a carbodiimide compound can suppress the generation of isocyanate gas (see, for example, Patent Document 1). Furthermore, using a carbodiimide compound with a specific structure can reduce the generation of isocyanate gas (see, for example, Patent Document 2). However, it has been found that even when the generation of isocyanate gas during heating is low, the surface appearance of the resulting molded article can deteriorate. The present disclosure aims to provide a resin composition and a molded article that generate less isocyanate gas and have a better surface appearance.

[0005] The present disclosure has the following aspects: [1] A resin composition comprising a polyester resin (A) and a carbodiimide compound, wherein the carbodiimide compound comprises a carbodiimide compound (B) represented by the following general formula (1), and the surface of a molded article comprising the resin composition has a surface roughness of 100 μm or less observed under an optical microscope: ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ The resin composition, (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different.２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound comprises a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compounds is 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.) [2] The resin composition according to [1], wherein the amount of isocyanate gas generated when the resin composition is heated at 260°C for 10 minutes is less than 100 ppm. [3] The resin composition according to [1] or [2], wherein the carbodiimide compound (B) is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the polyester resin (A). [4] The resin composition according to any one of [1] to [3], wherein the polyester resin (A) comprises polybutylene terephthalate. [5] The resin composition according to any one of [1] to [4], which contains a resin (C) different from the polyester resin (A). [6] A molded article comprising the resin composition according to any one of [1] to [5], wherein the surface of the molded article is observed through an optical microscope and has a viscosity of 100 μm or less. ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２[7] The molded article according to [6], wherein the amount of isocyanate gas generated when the molded article is heated at 260°C for 10 minutes is less than 100 ppm. [8] The molded article according to [6] or [7], wherein the carbodiimide compound (B) is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the polyester resin (A). [9] A method for producing a resin composition containing a polyester resin (A) and a carbodiimide compound (B) represented by the following general formula (1), comprising the following steps (I) or (II): step (I): a step comprising a first step of kneading the carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a master batch, and a second step of kneading the polyester resin (A) with the master batch; step (II): a step comprising kneading the polyester resin (A) with the carbodiimide compound (B) in an extruder, wherein the temperature of the extruder inlet section when the carbodiimide compound (B) is introduced into the extruder is 200°C or lower; A method for producing a resin composition. (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compounds is 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.

[10] The method for producing a resin composition according to [9], wherein the first step in the step (I) is carried out using an extruder, and the temperature of the extruder feeding section when the carbodiimide compound (B) is fed into the extruder is 200°C or lower.

[11] The method for producing a resin composition according to [9], wherein in step (II), the carbodiimide compound (B) is introduced into the extruder in the form of a masterbatch containing the carbodiimide compound (B) and a resin (C) different from the polyester resin (A).

[12] The method for producing a resin composition according to any one of [9] to

[11] , wherein the masterbatch contains 10 to 90 parts by mass of carbodiimide per 100 parts by mass of the masterbatch.

[0006] According to the present disclosure, it is possible to provide a resin composition and a molded article that generate less isocyanate gas and have a better surface appearance.

[0007] An embodiment of the present invention will be described in detail below. This embodiment is not limited to the following embodiment and can be implemented with appropriate modifications within the scope that does not impair the effects of this embodiment. Each configuration and their combinations in each embodiment are merely examples, and addition, omission, substitution, and other modifications of configurations are possible as appropriate within the scope that does not deviate from the spirit of this embodiment. This embodiment is not limited by the embodiment, but is limited only by the claims. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. If a specific description given for one embodiment also applies to other embodiments, that description may be omitted in other embodiments. In this embodiment, the expression "X to Y" regarding a numerical range means "greater than or equal to X and less than or equal to Y."

[0008] [First embodiment: Resin composition] A first embodiment of the present disclosure is a resin composition including a polyester resin (A) and a carbodiimide compound, wherein the carbodiimide compound includes a carbodiimide compound (B) represented by the following general formula (1), and the surface of a molded article including the resin composition is observed with an optical microscope to have a 100 μm ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ The present invention relates to a resin composition having a viscosity of less than 1000 MPa. (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compounds is taken as 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.) The first embodiment can provide a resin composition and a molded article that generate less isocyanate gas and have less foreign matter, resulting in a better surface appearance.

[0009] <Polyester Resin (A)> In one embodiment, the polyester resin (A) may be a C polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), or polybutylene terephthalate (PBT). ２－６ The polyester resin (A) may be one or more selected from the above-mentioned alkylene arylate resins.

[0010] In one embodiment, the polyester resin (A) preferably contains polybutylene terephthalate. In one embodiment, the polyester resin (A) preferably contains at least terephthalic acid or an ester-forming derivative thereof (C １－６ It is preferable that the polyester resin (A) contains polybutylene terephthalate obtained by polycondensation of a dicarboxylic acid component containing an alkylene glycol (such as an alkyl ester or acid halide of alkylene glycol or the like) and a glycol component containing an alkylene glycol having at least 4 carbon atoms (such as 1,4-butanediol) or an ester-forming derivative thereof (such as an acetylated product). In one embodiment, the polybutylene terephthalate contained in the polyester resin (A) is not limited to homopolybutylene terephthalate, and may be a copolymer containing 60 mol % or more of butylene terephthalate units.

[0011] The amount of terminal carboxyl groups in the polybutylene terephthalate contained in the polyester resin (A) is not particularly limited as long as it does not impede the object of the present disclosure, but is preferably 30 meq / kg or less, more preferably 25 meq / kg or less.

[0012] The intrinsic viscosity of the polybutylene terephthalate resin is not particularly limited as long as it does not impair the objectives of the present disclosure, but is preferably 0.60 dL / g or more and 1.2 dL / g or less, and more preferably 0.65 dL / g or more and 0.9 dL / g or less. When a polybutylene terephthalate resin having an intrinsic viscosity within this range is used, the resulting polybutylene terephthalate resin composition exhibits particularly excellent moldability. The intrinsic viscosity can also be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL / g can be prepared by blending a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL / g with a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL / g. The intrinsic viscosity of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at 35°C.

[0013] In preparing polybutylene terephthalate resin, when an aromatic dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof is used as a comonomer component, for example, a C 2 carboxylic acid such as isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, or 4,4'-dicarboxydiphenyl ether is used. ８－１４ aromatic dicarboxylic acids of C, such as succinic acid, adipic acid, azelaic acid, and sebacic acid; ４－１６ alkanedicarboxylic acids such as cyclohexanedicarboxylic acid; ５－１０ cycloalkanedicarboxylic acids of the formula (C); ester-forming derivatives of these dicarboxylic acid components (C １－６ These dicarboxylic acid components can be used alone or in combination of two or more. Among these dicarboxylic acid components, C carboxylic acid components such as isophthalic acid are preferred. ８－１２ Aromatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid６－１２ The alkanedicarboxylic acids are more preferred.

[0014] In the preparation of polybutylene terephthalate, when a glycol component other than 1,4-butanediol is used as a comonomer component, for example, a C 1,4-butanediol such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, or 1,3-octanediol may be used. ２－１０ alkylene glycols such as diethylene glycol, triethylene glycol, dipropylene glycol, and the like; alicyclic diols such as cyclohexanedimethanol and hydrogenated bisphenol A, and the like; aromatic diols such as bisphenol A and 4,4'-dihydroxybiphenyl, and the like; C-type alkylene glycols of bisphenol A such as ethylene oxide 2-mol adduct of bisphenol A and propylene oxide 3-mol adduct of bisphenol A, and the like; ２－４ or alkylene oxide adducts of these glycols; or ester-forming derivatives of these glycols (acetylated products, etc.). These glycol components can be used alone or in combination of two or more. Among these glycol components, C ２－６ More preferred are alkylene glycols such as those listed above, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol.

[0015] Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4'-hydroxybiphenyl; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C hydroxycarboxylic acids such as propiolactone, butyrolactone, valerolactone, and caprolactone (ε-caprolactone, etc.); ３－１２ lactones; ester-forming derivatives of these comonomer components (C １－６ alkyl ester derivatives, acid halides, acetylated derivatives, etc.

[0016] The content of the polyester resin (A) is preferably 30 to 100% by mass, more preferably 30 to 90% by mass, even more preferably 50 to 80% by mass, and particularly preferably 60 to 70% by mass of the total mass of the resin composition. The content of the polyester resin (A) in the thermoplastic resin contained in the resin composition is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and may be 100% by mass.

[0017] <Carbodiimide Compound (B)> The carbodiimide compound (B) used in the resin composition according to the first embodiment is a compound having a carbodiimide group (—N═C═N—) in the molecule and is represented by the following general formula (1). (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compound is taken as 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.

[0018] In one embodiment, the diisocyanate compound is preferably a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate. When the total amount of diisocyanate compounds is taken as 100 mol%, the proportion of 2,4'-MDI is preferably 30 to 70 mol% and the proportion of 4,4'-MDI is preferably 30 to 70 mol%. When the proportion of 2,4'-MDI is 30 mol% or more, the carbodiimide compound (B) is less likely to gel, and storage stability and solubility in solvents can be improved. Furthermore, by setting the proportion of 2,4'-MDI to 70 mol% or less, steric hindrance is not too great, the reactivity of the carbodiimide compound (B) is improved, and desired performance can be easily achieved when used with the polyester resin (A). From this viewpoint, the proportion of 2,4'-MDI in the diisocyanate compound is more preferably 40 to 65 mol%, and even more preferably 50 to 60 mol%, and the proportion of 4,4'-MDI is more preferably 35 to 60 mol%, and even more preferably 40 to 50 mol%.

[0019] In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ The organic compound having one functional group capable of reacting with an isocyanate group (hereinafter also simply referred to as "organic compound") is not particularly limited as long as it has one functional group capable of reacting with an isocyanate group, but from the viewpoint of reactivity, it is preferably one or more compounds selected from monoisocyanates, monoalcohols, monoamines, monocarboxylic acids, and acid anhydrides.

[0020] (n) In the above general formula (1), n ​​represents a number of 1 to 15. From the viewpoint of suppressing an increase in the melt viscosity of the polyester resin composition, n is preferably 1 to 9.

[0021] Monoisocyanates are preferred because they can increase the content of carbodiimide groups in the carbodiimide compound (B). Examples of monoisocyanates include lower alkyl isocyanates such as methyl isocyanate, ethyl isocyanate, propyl isocyanate, n-, sec-, or tert-butyl isocyanate; alicyclic isocyanates such as cyclohexyl isocyanate; and aromatic isocyanates such as phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, and 2,6-diisopropylphenyl isocyanate. Among these, from the viewpoint of reactivity, phenyl isocyanate and tolyl isocyanate are preferred, and phenyl isocyanate is more preferred.

[0022] Monoalcohols are preferred because they have high reactivity with isocyanate groups and facilitate the synthesis of the carbodiimide compound (B). Examples of monoalcohols include aliphatic alcohols, alicyclic alcohols, and polyether monools. Examples of such monoalcohols include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, 2-methylpropanol, 2-methyl-2-propanol, 2-ethylhexanol, cyclohexanol, dodecyl alcohol, polyethylene glycol monomethyl ether, and polypropylene glycol monomethyl ether. Among these, from the viewpoint of providing a carbodiimide compound (B) having excellent handleability and excellent processability with the polyester resin (A), methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, 2-methylpropanol, 2-methyl-2-propanol, 2-ethylhexanol, cyclohexanol, and dodecyl alcohol are preferred, and 1-propanol, isopropanol, 1-butanol, 2-butanol, 2-methylpropanol, 2-methyl-2-propanol, 2-ethylhexanol, and dodecyl alcohol are more preferred.

[0023] Monoamines are preferred because they have high reactivity with isocyanate groups, making it easy to synthesize the carbodiimide compound (B), and because they have excellent compatibility with the polyester resin (A). Examples of monoamines include primary or secondary alkylamines. Examples of such monoamines include primary amines such as butylamine and cyclohexylamine; and secondary amines such as diethylamine, dibutylamine, and dicyclohexylamine. Among these, butylamine and cyclohexylamine are preferred, and butylamine is more preferred, from the viewpoint of improving processability with the polyester resin (A).

[0024] The monocarboxylic acid and the acid anhydride react with the isocyanate group to form a bond site (X in the above general formula (1)). １ , X ２ ) are preferred in terms of excellent heat resistance. Examples of monocarboxylic acids include formic acid, acetic acid, propionic acid, isovaleric acid, hexanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachic acid, oleic acid, linoleic acid, linolenic acid, and benzoic acid. Among these, from the viewpoint of improving processability with the polyester-based resin (A), acetic acid and propionic acid are preferred, and acetic acid is more preferred. Examples of acid anhydrides include phthalic anhydride, acetic anhydride, succinic anhydride, maleic anhydride, and benzoic anhydride. From the viewpoint of improving processability with the polyester-based resin (A), acetic anhydride and succinic anhydride are preferred, and acetic anhydride is more preferred.

[0025] (X １ , X ２ In the above general formula (1), X １ , X ２ represents a group formed by a reaction between a functional group capable of reacting with an isocyanate group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ For example, when the organic compound is a monoisocyanate, X １ , X ２ is a group represented by the following formula (I), and when the organic compound is a monoalcohol, X １ , X ２is a group represented by the following formula (II), and when the organic compound is a monoamine, X １ , X ２ is a group represented by the following formula (III), and when the organic compound is a monocarboxylic acid, X １ , X ２ is a group represented by the following formula (IV), and when the organic compound is an acid anhydride, X １ , X ２ is a group represented by the following formula (V):

[0026]

[0027]

[0028]

[0029]

[0030] By including the carbodiimide compound (B) represented by the general formula (1), a resin composition that generates less isocyanate gas can be obtained. Although the carbodiimide compound can be used in combination with other carbodiimide compounds other than the carbodiimide compound (B), it is preferable to use only the carbodiimide compound (B) from the viewpoint of further suppressing the generation of isocyanate gas.

[0031] In one embodiment, it is preferable that the amount of isocyanate gas generated when the resin composition is heated at 260° C. for 10 minutes is less than 100 ppm. When the resin composition is heated at 260° C. for 10 minutes, the amount of isocyanate gas generated is less than 100 ppm, and the resin composition and molded article are therefore more excellent in safety.

[0032] In one embodiment, the content of the carbodiimide compound (B) in the resin composition is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, even more preferably 0.2 to 3 parts by mass, and particularly preferably 0.3 to 2 parts by mass, relative to 100 parts by mass of the polyester resin (A). By setting the content of the carbodiimide compound (B) within the above range relative to 100 parts by mass of the polyester resin (A), it is possible to provide a resin composition and a molded article with better surface appearance due to less generation of isocyanate gas and less foreign matter.

[0033] In one embodiment, it is preferable to include a resin (C) of a different type from the polyester resin (A). By including a resin (C) of a different type from the polyester resin (A), less isocyanate gas is generated during heating, and there is less foreign matter, making it possible to provide a resin composition and a molded article with better surface appearance. In one embodiment, examples of the resin (C) of a different type from the polyester resin (A) include polyethylene resin, polypropylene resin, polybutylene succinate resin, polybutylene terephthalate resin, polyamide resin, polycarbonate resin, polyarylene sulfide resin, polyacetal resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, polysulfone resin, polyethersulfone resin, polyetherimide resin, and polyetherketone resin. As the resin (C), one or more selected from the above can be used. The content of the resin (C) is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the polyester resin (A).

[0034] <100 μm observed when observing the surface of a molded article containing a resin composition with an optical microscope ２ In this embodiment, the number of foreign particles having an area of ​​100 μm or more observed when the surface of a molded article containing a resin composition is observed with an optical microscope ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ The surface of a molded article containing the resin composition is observed under an optical microscope to have a particle size of less than 100 μm.２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ By having a density of less than 100 μm, it is possible to provide a resin composition and a molded article with a better surface appearance, in which the resin composition generates less isocyanate gas. Also, it is possible to prevent a decrease in strength caused by foreign matter. In this specification, the "number of foreign matters" is calculated by calculating the area of ​​the target surface of a molded article of any shape, and observing it with an optical microscope set at any magnification. ２ Count the foreign objects with an area of ​​100cm or more. ２ The number of foreign objects per 100cm is calculated by converting the number of foreign objects per 100cm. ２ The "foreign matter" is observed under an optical microscope as a discolored area.

[0035] In one embodiment, the surface of a molded article containing the resin composition is observed with an optical microscope. ２ The number of foreign objects with an area of ​​9 or more per 100 cm ２ Preferably, it is less than 8 pieces / 100 cm ２ More preferably, it is less than 7 pieces / 100 cm ２ It is even more preferable that the number of pieces is less than 6 pieces / 100 cm. ２ More preferably, it is less than 5 pieces / 100 cm ２ It is particularly preferable that the number of foreign particles is less than 10 / 100 cm. ２ Examples of methods for making the total mass of a resin composition less than 10 ...

[0036] (Other Components) The resin composition of the embodiment of the present disclosure may contain known substances that are generally added to thermoplastic resins and thermosetting resins, for example, stabilizers such as antioxidants and ultraviolet absorbers, reinforcing fillers such as circular cross-section glass fibers, antistatic agents, colorants such as dyes and pigments, mold release agents, lubricants, crystallization accelerators, crystal nucleating agents, etc., in order to impart desired properties according to the purpose, within a range that does not impair the effects of the present disclosure.

[0037] (Method for producing resin composition) The method for producing the resin composition according to this embodiment is not particularly limited, and the resin composition can be prepared by a conventionally known method. For example, the resin composition is prepared by blending the components and melt-kneading them using a single-screw or twin-screw extruder. In one embodiment, the resin composition according to this embodiment is preferably produced by the method for producing a resin composition according to an embodiment described below.

[0038] [Second embodiment: Molded article] A second embodiment of the present invention is a molded article containing the resin composition described above, wherein the molded article has a surface area of ​​100 μm observed through an optical microscope. ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ According to the second embodiment, it is possible to provide a resin composition and a molded article that generate less isocyanate gas and have less foreign matter, resulting in a better surface appearance.

[0039] The molded article in this embodiment is a molded article containing the resin composition according to the above embodiment. The molding method is not particularly limited, and known molding methods can be used. For example, the molded article can be produced by (1) mixing the components, kneading and extruding them in a single- or twin-screw extruder to prepare pellets, and then molding them; (2) first preparing pellets (master batches) with different compositions, mixing (diluting) a predetermined amount of the pellets, and molding them to obtain a molded article of a predetermined composition; or (3) directly charging one or more of the components into a molding machine. The pellets may be prepared, for example, by melt-mixing components other than a brittle component (such as a glass-based reinforcing material) and then mixing the brittle component. The molding method for other molded articles made of thermoplastic resins is also not particularly limited, and known molding methods can be used.

[0040] The molded article may be produced by melt-kneading the resin composition and molding it by a conventional method such as extrusion molding, injection molding, compression molding, blow molding, vacuum molding, rotational molding, or gas injection molding, but is usually molded by injection molding. The mold temperature during injection molding is usually about 40 to 120°C, preferably about 50 to 90°C, and more preferably about 60 to 80°C.

[0041] The molded article may contain a colorant, such as inorganic pigments (black pigments such as carbon black (e.g., acetylene black, lamp black, thermal black, furnace black, channel black, and ketjen black), red pigments such as iron oxide red, orange pigments such as molybdate orange, and white pigments such as titanium oxide), and organic pigments (yellow pigments, orange pigments, red pigments, blue pigments, and green pigments).

[0042] <100 μm observed on the surface of the molded product through an optical microscope ２ In this embodiment, the number of foreign particles having an area of ​​100 μm or more observed when observing the surface of a molded product with an optical microscope ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ The surface of the molded product is observed under an optical microscope with a particle size of less than 100 μm. ２The number of foreign objects with an area of ​​10 or more per 100 cm ２ In this specification, the term "number of foreign matters" refers to the number of foreign matters per 100 μm2 calculated by calculating the area of ​​the target surface of a molded article of any shape and observing it with an optical microscope set at any magnification. ２ Count the foreign objects with an area of ​​100cm or more. ２ The number of foreign objects per 100cm is calculated by converting the number of foreign objects per 100cm. ２ " is a numerical value with units of ".

[0043] In one embodiment, the amount of isocyanate gas generated when the molded article is heated for 10 minutes at 260° C. is preferably less than 100 ppm. Since the amount of isocyanate gas generated when heated for 10 minutes at 260° C. is less than 100 ppm, the molded article of this embodiment is more excellent in safety.

[0044] In one embodiment, the polyester resin (A) preferably contains 0.1 to 5 parts by mass of the carbodiimide compound relative to 100 parts by mass of the polyester resin (A). By containing 0.1 to 5 parts by mass of the carbodiimide compound relative to 100 parts by mass of the polyester resin (A), a molded article that generates less isocyanate gas can be obtained.

[0045] [Third embodiment: method for producing resin composition] A third embodiment of the present embodiment relates to a method for producing a resin composition comprising a polyester resin (A) and a carbodiimide compound (B) represented by the following general formula (1), which comprises the following steps (I) or (II): step (I): a step comprising a first step of kneading the carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a master batch, and a second step of kneading the polyester resin (A) with the master batch; step (II): a step comprising kneading the polyester resin (A) with the carbodiimide compound (B) in an extruder, wherein the temperature of the extruder feeding section when feeding the carbodiimide compound (B) into the extruder is 200°C or lower; (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compound is taken as 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.

[0046] According to the third embodiment, a resin composition with a better surface appearance can be produced with less isocyanate gas generation and less foreign matter. In one embodiment, the method for producing a resin composition includes step (I). When step (I) is included, the temperature of the extruder inlet when the carbodiimide compound (B) is introduced into the extruder is not limited and may exceed 200°C, for example. In another embodiment, the method for producing a resin composition includes step (II). When step (II) is included, the carbodiimide compound (B) may be introduced in the form of a masterbatch or as is.

[0047] In this specification, "extruder" refers to a general extruder equipped with a raw material charging mechanism (hopper), a cylinder, and at least one screw in the cylinder, and having a mechanism in which a resin is melted in the cylinder by heat from a temperature control mechanism (heater and cooler) and shear heat from the screw, kneaded while being transported forward by the screw, and extruded from a mold at the end portion called a die. In this specification, "extruder charging section" refers to the portion of the cylinder directly below the hopper. The temperature of the "extruder charging section" is preferably maintained at a constant temperature by a temperature control mechanism (heater and cooler). It is preferable that the entire cylinder is divided into two or more blocks, and each block is controlled at a different temperature.

[0048] <Step (I)> In this embodiment, step (I) includes a first step of kneading the carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a masterbatch, and a second step of kneading the polyester resin (A) with the masterbatch. By using a masterbatch containing the carbodiimide compound (B) and a resin (C) different from the polyester resin (A), it is possible to easily produce a resin composition with a better surface appearance due to less isocyanate gas generation and less foreign matter. (Step 1) In step 1, the carbodiimide compound (B) is kneaded with a resin (C) different from the polyester resin (A) to obtain a masterbatch. The different resin (C) is as described above. The method for preparing the masterbatch is not particularly limited, and the masterbatch can be produced by kneading the carbodiimide compound (B) with a resin (C) different from the polyester resin (A) using a conventional method. For example, the resin composition can be produced by adding the carbodiimide compound (B) and a resin (C) different from the polyester resin (A) to a mixer, mixing them uniformly, and then melting and kneading them in an extruder. The amount of the carbodiimide compound (B) is preferably 10 to 900 parts by mass, and more preferably 50 to 200 parts by mass, per 100 parts by mass of the resin (C). The amount of the resin (C) is preferably 0.1 to 5 parts by mass, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the polyester resin (A). In one embodiment, the first step in step (I) is carried out using an extruder, and the temperature of the extruder inlet when the carbodiimide compound (B) is introduced into the extruder is preferably 200°C or lower, more preferably 195°C or lower, and even more preferably 190°C or lower. In the step (I), the first step is carried out using an extruder, and by setting the temperature of the extruder inlet section when the carbodiimide compound (B) is introduced into the extruder at 200° C. or less, a rapid increase in the reaction rate of the dimerization reaction in the cylinder is suppressed, the reaction proceeds gently throughout the extruder, and the generation of foreign matter is further suppressed. (Second Step) In the second step, the polyester resin (A) and the masterbatch are kneaded.The kneading temperature is not limited, and is, for example, preferably 230 to 310°C, and more preferably 250 to 280°C. The kneading method is not limited, and kneading can be performed using a known extruder. The amount of the masterbatch is preferably such that the amount of the carbodiimide compound (B) is 0.1 to 5 parts by mass, and more preferably 0.3 to 2 parts by mass, per 100 parts by mass of the polyester resin (A).

[0049] <Step (II)> In this embodiment, step (II) includes kneading the polyester resin (A) and the carbodiimide compound (B) in an extruder, and is a step in which the temperature of the extruder inlet when the carbodiimide compound (B) is introduced into the extruder is 200°C or lower. By introducing the carbodiimide compound (B) into the extruder at a temperature of 200°C or lower, less isocyanate gas is generated and there is less foreign matter, making it possible to easily produce a resin composition with a better surface appearance. The temperature of the extruder inlet when introducing the carbodiimide compound (B) into the extruder is preferably 195°C or lower, more preferably 190°C or lower. In one embodiment, in step (II), the carbodiimide compound (B) is preferably introduced into the extruder in the form of a masterbatch containing the carbodiimide compound (B) and a resin (C) different from the polyester resin (A). By adding the carbodiimide compound (B) and a resin (C) different from the polyester resin (A) to the extruder in the form of a masterbatch, it is possible to easily produce a resin composition with a better surface appearance due to less isocyanate gas generation and less foreign matter. The method for preparing the masterbatch is not particularly limited, and the masterbatch can be produced by kneading the carbodiimide compound (B) and the resin (C) different from the polyester resin (A) using a conventional method. For example, the masterbatch can be produced by adding the carbodiimide compound (B) and the resin (C) different from the polyester resin (A) to a mixer and mixing them uniformly, followed by melting and kneading them in an extruder. Step (II) includes kneading the polyester resin (A) and the carbodiimide compound (B) in an extruder, and in step (II), the carbodiimide compound (B) is introduced into the extruder in the form of a masterbatch containing the carbodiimide compound (B) and a resin (C) different from the polyester resin (A), thereby suppressing a rapid dimerization reaction in the cylinder, allowing the reaction to proceed gently throughout the entire extruder, and further suppressing the generation of foreign matter.

[0050] In one embodiment, in the above steps (I) and (II), the masterbatch preferably contains 10 to 90 parts by mass, more preferably 20 to 80 parts by mass, and even more preferably 30 to 70 parts by mass of carbodiimide relative to 100 parts by mass of the masterbatch.

[0051] The present embodiment will be described in more detail below by showing examples, but interpretation of the present disclosure is not limited to these examples.

[0052] [Raw Materials] The raw materials used in the Examples and Comparative Examples are as follows. <Polyethylene Resin> A: Polybutylene terephthalate manufactured by Polyplastics (IV: 0.83 dL / g, amount of carboxylic acid terminals: 16 mmol / kg) <Carbodiimides> B-1-1: Carbodiimide compound (Synthesis Example 1 below) B-1-2: Carbodiimide compound (Synthesis Example 2 below) B-1-3: Carbodiimide compound (Synthesis Example 3 below) B-2: Carbodiimide manufactured by Lanxess (Stabaxol P-100)

[0053] The various materials used in the synthesis examples, examples, and comparative examples are listed below. <Diisocyanate compounds> - Mixture of 54 mass% of 2,4'-diphenylmethane diisocyanate and 46 mass% of 4,4'-diphenylmethane diisocyanate (mixture of 2,4'-MDI (54%) and 4,4'-MDI (46%)): manufactured by Tosoh Corporation, product name "Monomeric MDI; Millionate NM" <End-capping agents> - Dodecyl alcohol: manufactured by Kanto Chemical Co., Inc. - Cyclohexylamine: manufactured by Tokyo Chemical Industry Co., Ltd. - Phenyl isocyanate: manufactured by Tokyo Chemical Industry Co., Ltd. <Carbodiimide catalysts> - 3-methyl-1-phenyl-2-phospholene-1-oxide: manufactured by Tokyo Chemical Industry Co., Ltd.

[0054] Synthesis Example 1: 100 parts by mass of a mixture of 54% by mass of 2,4'-diphenylmethane diisocyanate and 46% by mass of 4,4'-diphenylmethane diisocyanate, 21.3 parts by mass of dodecyl alcohol, and 0.5 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide were placed in a reaction vessel equipped with a reflux condenser and a stirrer, and stirred for 2 hours at 100°C under a nitrogen stream. Thereafter, infrared absorption (IR) spectroscopy confirmed that the absorption peak due to the isocyanate group at a wavelength of around 2270 cm-1 had almost disappeared, yielding carbodiimide compound B-1-1 where n=6.

[0055] Synthesis Example 2: 100 parts by mass of a mixture of 54% by mass of 2,4'-diphenylmethane diisocyanate and 46% by mass of 4,4'-diphenylmethane diisocyanate, 7.9 parts by mass of cyclohexylamine, and 0.5 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide were placed in a reaction vessel equipped with a reflux condenser and a stirrer, and the mixture was stirred for 2 hours at 100°C under a nitrogen stream. Thereafter, infrared absorption (IR) spectroscopy confirmed that the absorption peak due to the isocyanate group at a wavelength of around 2270 cm-1 had almost disappeared, yielding carbodiimide compound B-1-2 where n=9.

[0056] (Synthesis Example 3) 100 parts by mass of a mixture of 54% by mass of 2,4'-diphenylmethane diisocyanate and 46% by mass of 4,4'-diphenylmethane diisocyanate, 31.7 parts by mass of phenyl isocyanate, and 0.5 parts by mass of 3-methyl-1-phenyl-2-phospholene-1-oxide were placed in a reaction vessel equipped with a reflux condenser and a stirrer, and stirred for 2 hours at 100°C under a nitrogen stream. Thereafter, infrared absorption (IR) spectroscopy confirmed that the absorption peak due to the isocyanate group at a wavelength of approximately 2270 cm-1 had almost disappeared, yielding a carbodiimide compound B-1-3 where n = 2. <Masterbatch> C-1-1: A masterbatch prepared by adding equal amounts of polyethylene (F120N MI: 1.2 g / 10 min (180°C)) manufactured by Ube Industries, Ltd. and B-1-1.・C-1-2: A masterbatch formed by adding equal amounts of polyethylene manufactured by Ube Industries (F120N MI: 1.2g / 10min (180°C)) and B-1-2. ・C-1-3: A masterbatch formed by adding equal amounts of polyethylene manufactured by Ube Industries (F120N MI: 1.2g / 10min (180°C)) and B-1-3. ・C-2-1: A masterbatch formed by adding equal amounts of polyethylene manufactured by Ube Industries (F522N MI: 5g / 10min (180°C)) and B-1-1. ・C-2-2: A masterbatch formed by adding equal amounts of polyethylene manufactured by Ube Industries (F522N MI: 5g / 10min (180°C)) and B-1-2.・C-2-3: A masterbatch obtained by adding equal amounts of polyethylene manufactured by Ube Industries (F522N MI: 5g / 10min (180°C)) and B-1-3. ・C-3-1: A masterbatch obtained by adding equal amounts of polyethylene manufactured by Ube Industries (J1019 MI: 10g / 10min (180°C)) and B-1-1. ・C-3-2: A masterbatch obtained by adding equal amounts of polyethylene manufactured by Ube Industries (J1019 MI: 10g / 10min (180°C)) and B-1-2. ・C-3-3: A masterbatch obtained by adding equal amounts of polyethylene manufactured by Ube Industries (J1019 MI: 10g / 10min (180°C)) and B-1-3. C-4-1: A masterbatch prepared by adding equal amounts of polyethylene manufactured by Ube Industries (J3519 MI: 35 g / 10 min (180°C)) and B-1-1.・C-4-2: A masterbatch formed by adding equal amounts of Ube Industries polyethylene (J3519 MI: 35g / 10min (180°C)) and B-1-2. ・C-4-3: A masterbatch formed by adding equal amounts of Ube Industries polyethylene (J3519 MI: 35g / 10min (180°C)) and B-1-3. ・C-5-1: A masterbatch formed by adding SunAllomer polypropylene and B-1-1 in a 6:4 ratio. ・C-5-2: A masterbatch formed by adding SunAllomer polypropylene and B-1-2 in a 6:4 ratio. ・C-5-3: A masterbatch formed by adding SunAllomer polypropylene and B-1-3 in a 6:4 ratio.・C-6-1: A masterbatch obtained by adding SunAllomer polypropylene (PM900A MI: 30g / 10min (230°C)) and B-1-1 in a 6:4 ratio. ・C-6-2: A masterbatch obtained by adding SunAllomer polypropylene (PM900A MI: 30g / 10min (230°C)) and B-1-2 in a 6:4 ratio. ・C-6-3: A masterbatch obtained by adding SunAllomer polypropylene (PM900A MI: 30g / 10min (230°C)) and B-1-3 in a 6:4 ratio. ・C-7-1: A masterbatch obtained by adding SunAllomer polypropylene and B-1-1 in a 6:4 ratio. ・C-7-2: A masterbatch obtained by adding SunAllomer polypropylene and B-1-2 in a 6:4 ratio.・C-7-3: A masterbatch made by adding SunAllomer polypropylene and B-1-3 in a 6:4 ratio. ・C-8-1: A masterbatch made by adding equal amounts of Mitsubishi Chemical Corporation's polybutylene adipate succinate and B-1-1. ・C-8-2: A masterbatch made by adding equal amounts of Mitsubishi Chemical Corporation's polybutylene adipate succinate and B-1-2. ・C-8-3: A masterbatch made by adding equal amounts of Mitsubishi Chemical Corporation's polybutylene adipate succinate and B-1-3. ・C-9: A masterbatch made by adding equal amounts of Ube Industries' polyethylene (F120N MI: 1.2g / 10min (180°C)) and B-2. ・C-10-1: A masterbatch made by adding equal amounts of A and B-1-1.C-10-2: A masterbatch obtained by adding equal amounts of A and B-1-2. C-10-3: A masterbatch obtained by adding equal amounts of A and B-1-3.

[0057] <Method for producing master batch> Using a twin-screw extruder (TEX-30 manufactured by The Japan Steel Works, Ltd.), each polymer other than B-1-1, B-1-2, B-1-3, or B-2 in C-1-1 to C-10-3 above was fed into the extruder, and the extruder and cylinder temperatures when feeding the carbodiimides according to B-1-1, B-1-2, B-1-3, or B-2 into the extruder were set as follows, and the mixture was kneaded and pelletized to produce each of the master batches according to C-1-1 to C-10-3.・C-1-1, C-1-2, C-1-3, C-2-1, C-2-2, C-2-3, C-3-1, C-3-2, C-3-3, C-4-1, C-4-2, C-4-3, C-9: 120℃ ・C-5-1, C-5-2, C-5-3: 160℃・C-6-1, C-6-2, C-6-3, C-7-1, C-7-2, C-7-3: 190℃ ・C-8-1, C-8-2, C-8-3: 130℃ ・C-10-1, C-10-2, C-10-3: 260℃

[0058] [Examples 1 to 39, Comparative Examples 1 to 12] The raw materials were mixed in the proportions shown in Tables 1 to 3, kneaded in a twin-screw extruder (TEX-30, manufactured by The Japan Steel Works), and then pelletized to produce each resin composition. The temperature of the extruder inlet section when adding the carbodiimide was set to the temperature shown in Table 1, and the temperature of the extruder cylinder section at other times was 250 ° C. Each resin composition was injection molded in an injection molding machine (ROBOSHOT S-2000i100B, manufactured by Fanuc Corporation) at a cylinder temperature of 260 ° C, a mold temperature of 80 ° C, an injection speed of 150 mm / sec, and a holding pressure of 60 MPa to produce a multipurpose test piece as specified in ISO 3167. In Table 1, "(I)" and "(II)" in "Step" indicate that the resin composition was produced by the following steps (I) and (II), respectively, and "-" indicates that the production method did not fall under either (I) or (II). Step (I): A step including a first step of kneading a carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a masterbatch, and a second step of kneading the polyester resin (A) with the masterbatch. Step (II): A step including kneading a polyester resin (A) with a carbodiimide compound (B) in an extruder, wherein the temperature of the extruder inlet when the carbodiimide compound (B) is introduced into the extruder is 200°C or lower.

[0059] [Evaluation] The following evaluations were carried out for each of the resin compositions and multipurpose test pieces according to the examples and comparative examples. The results are shown in Tables 1 and 2.

[0060] <Isocyanate gas generation amount evaluation>

[0061] 5 mg of each resin composition was heated at 260°C for 10 minutes, and the generated isocyanate gas was measured using a gas chromatograph / mass spectrometer system (GC-MS6890 / 5975, manufactured by Agilent Technologies Inc.). In Tables 1 and 2, 1 to 3 mean the following: 1: The amount of isocyanate gas detected was less than 100 ppm. 2: The amount of isocyanate gas detected was 100 ppm or more but less than 500 ppm. 3: The amount of isocyanate gas detected was 500 ppm or more.

[0062] <Measurement of the number of foreign particles> The surface of each multipurpose test piece according to the examples and comparative examples was observed with an optical microscope (scanner manufactured by Canon Inc.), and the size of the foreign particles (discolored portions) was measured. ２ Count the number of foreign objects above 100cm ２ per 100 μm ２ The number of foreign particles having an area equal to or greater than this was calculated.

[0063]

[0064]

[0065]

[0066] As shown in Tables 1 to 3, the resin compositions and molded articles according to the examples containing polyester resin (A) and masterbatches (C-1-1 to C-8-3) had a detected amount of isocyanate gas of less than 100 ppm and a maximum concentration of 100 μm ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ On the other hand, in the resin compositions and molded articles according to the comparative examples containing polyester resin (A) and carbodiimide compound B-2 or masterbatches (C-9, C-10-1 to C-10-3), the detected amount of isocyanate gas was less than 100 ppm or less than 100 μm ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ In other words, it was found that the resin composition of the present disclosure has a better surface appearance due to less isocyanate gas generation and less foreign matter. Furthermore, the resin composition and molded article according to the examples, which were produced by a production method including either of the following steps (I) and (II), had a detected amount of isocyanate gas of less than 100 ppm and a surface area of ​​100 μm ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２ On the other hand, in the resin composition and molded article according to the comparative example, which were not produced by the production method including either of the following steps (I) and (II), the detected amount of isocyanate gas was less than 100 ppm and the detected amount of isocyanate gas was less than 100 μm ２ The number of foreign objects with an area of ​​10 or more per 100 cm ２or less. It has been found that a resin composition manufacturing method including either step (I) or (II) produces less isocyanate gas and contains less foreign matter, resulting in a resin composition with a better surface appearance. Step (I): A process including a first step of kneading a carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a masterbatch, and a second step of kneading the polyester resin (A) with the masterbatch. Step (II): A process including kneading a polyester resin (A) with a carbodiimide compound (B) in an extruder, wherein the temperature of the extruder inlet when the carbodiimide compound (B) is introduced into the extruder is 200°C or lower.

[0067] The resin composition of the present embodiment can provide a resin composition and a molded article that generate less isocyanate gas and have a better surface appearance, and therefore can be suitably used for various resin compositions and molded articles, and for the production thereof, etc., and has industrial applicability. The method for producing a resin composition of the present embodiment can provide a resin composition and a molded article that generate less isocyanate gas and have a better surface appearance, and therefore can be suitably used for the production of various resin compositions and molded articles, and has industrial applicability.

Claims

1. A resin composition comprising a polyester resin (A) and a carbodiimide compound, wherein the carbodiimide compound comprises a carbodiimide compound (B) represented by the following general formula (1), and the surface of a molded article comprising the resin composition is observed under an optical microscope to have a thickness of 100 μm or less: ２ The number of foreign objects with an area of 10 or more per 100 cm ２ The resin composition, (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compound is taken as 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.

2. The resin composition according to claim 1, wherein the amount of isocyanate gas generated when the resin composition is heated at 260°C for 10 minutes is less than 100 ppm.

3. The resin composition according to claim 1 or 2, which contains 0.1 to 5 parts by mass of the carbodiimide compound (B) per 100 parts by mass of the polyester resin (A).

4. The resin composition according to claim 1 or 2, wherein the polyester resin (A) contains polybutylene terephthalate.

5. The resin composition according to claim 1 or 2, which contains a resin (C) different from the polyester resin (A).

6. A molded article containing the resin composition of claim 1, wherein the surface of the molded article is observed through an optical microscope to have a particle size of 100 μm or less. ２ The number of foreign objects with an area of 10 or more per 100 cm ２ less than, 7. The molded article according to claim 6, wherein the amount of isocyanate gas generated when the molded article is heated at 260°C for 10 minutes is less than 100 ppm.

8. The molded article according to claim 6 or 7, which contains 0.1 to 5 parts by mass of the carbodiimide compound (B) per 100 parts by mass of the polyester resin (A).

9. A method for producing a resin composition comprising a polyester resin (A) and a carbodiimide compound (B) represented by the following general formula (1), comprising the following step (I) or step (II): step (I): a step comprising a first step of kneading the carbodiimide compound (B) with a resin (C) different from the polyester resin (A) to obtain a masterbatch, and a second step of kneading the polyester resin (A) with the masterbatch; step (II): a step comprising kneading the polyester resin (A) with the carbodiimide compound (B) in an extruder, wherein the temperature of the extruder inlet section when the carbodiimide compound (B) is fed into the extruder is 200°C or lower; a method for producing a resin composition. (In general formula (1), R １ , R ３ represents a residue of an organic compound having one functional group capable of reacting with an isocyanate group, excluding the functional group; R １ , R ３ may be the same or different. ２ represents a divalent residue obtained by removing two isocyanate groups from a diisocyanate compound. ２ has a benzene-based aromatic ring directly bonded to the NCN group, and has no or only one substituent at both ortho positions of the benzene-based aromatic ring bonded to the NCN group. １ , X ２ represents a group formed by a reaction between the functional group of the organic compound and the isocyanate group of the diisocyanate compound, and X １ , X ２ may be the same or different. n represents a number from 1 to 15. The diisocyanate compound contains a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, and when the total amount of the diisocyanate compound is taken as 100 mol %, the proportion of the 2,4'-diphenylmethane diisocyanate is 30 to 70 mol %, and the proportion of the 4,4'-diphenylmethane diisocyanate is 30 to 70 mol %.

10. A method for producing a resin composition according to claim 9, wherein the first step in step (I) is carried out using an extruder, and the temperature of the extruder inlet section when the carbodiimide compound (B) is introduced into the extruder is 200°C or lower.

11. A method for producing a resin composition according to claim 9, wherein in step (II), the carbodiimide compound (B) is introduced into the extruder in the form of a masterbatch containing the carbodiimide compound (B) and a resin (C) of a type different from the polyester resin (A).

12. A method for producing a resin composition according to any one of claims 9 to 11, wherein the masterbatch contains 10 to 90 parts by mass of carbodiimide per 100 parts by mass of the masterbatch.

Images