Resin composition containing polyarylate resin and polyamide resin

Abstract

To provide a resin composition comprising a polyarylate resin and a polyamide resin, in which the resin composition itself exhibits sufficiently favorable color tone and is capable of effectively reducing coloration caused by heat deterioration in melt molding.SOLUTION: A resin composition includes a polyarylate resin (A), which contains an aromatic dicarboxylic acid component and a divalent phenol component as monomer components, and a polyamide resin (B), the mass ratio (A / B) between the polyarylate resin (A) and the polyamide resin (B) being in the range of 99 / 1 to 1 / 99, and the content of formate being 0.1-2.0 ppm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing a polyarylate resin and a polyamide resin. [Background technology]

[0002] Polyarylate resins, which are composed of aromatic dicarboxylic acid components and dihydric phenol components, are amorphous, transparent, and have excellent heat resistance. Resin compositions obtained by blending polyamide resins with the polyarylate resins are opaque but have excellent chemical resistance and moldability, and are therefore widely used as metal replacement materials, primarily in the electrical and electronic fields. Furthermore, resin compositions obtained by blending polyamide resins and glass fibers with the polyarylate resins have excellent rigidity, chemical resistance, heat resistance, water resistance, and moldability, and are therefore widely used in mechanical parts such as watch cases, automotive parts, and electrical parts.

[0003] However, due to its excellent heat resistance, polyarylate resins are often subjected to higher melt-molding temperatures than general-purpose polymers, and are prone to thermal degradation and discoloration during melting. Furthermore, molded articles tend to yellow when used at high temperatures for long periods of time. Therefore, resin compositions containing polyarylate resins and polyamide resins have sometimes been restricted in use for applications requiring color tone and undesirable color tone changes over time, such as machine parts and automobile parts.

[0004] To solve the above problems, various methods have been investigated for adding modifiers such as dyes, pigments, and antioxidants during melt molding or melt kneading. For example, Patent Document 1 proposes a method of melt kneading a dye, pigment, and sulfur-containing carboxylic acid ester with a polycarbonate resin. Furthermore, Patent Document 2 proposes a method of melt kneading a phenolic compound, a phosphorus-based compound, and a lactone-based compound with a polyarylate resin. However, these methods rely solely on additives added during melt kneading, and therefore there is a need to improve the color tone and thermal discoloration of the polyarylate resin itself, in order to reduce the number and amount of additives used.

[0005] In order to improve the color tone and thermal discoloration of the polyarylate resin itself, it is necessary to devise an ingenuity in the stage of producing the polyarylate resin from raw materials. As polymerization methods for polyarylate resin, melt polymerization, solution polymerization, and interfacial polymerization are known. In particular, the interfacial polymerization method is suitable for polymers with high heat resistance, because the reaction proceeds to a high degree of polymerization at temperatures close to room temperature, resulting in a resin with excellent color tone, and making full use of the transparency and heat resistance that are inherent characteristics of polyarylate resin.

[0006] Furthermore, as described in Patent Document 3, although not limited to the interfacial polymerization method, adding a reducing agent such as sodium hydrosulfite during the polymerization process is effective in preventing discoloration of the dihydric phenol compound monomer and further coloration of the resulting polyarylate resin.

[0007] On the other hand, Patent Document 4 discloses a technique for producing an aromatic polycarbonate having excellent color tone and heat resistance by using sodium hydrosulfite as a reducing agent added during the polymerization process.

[0008] Furthermore, Patent Document 5 discloses a technology for producing polycarbonate with excellent hue by limiting the sodium formate content in sodium hydrosulfite used in the production of polycarbonate to 0.3 wt % or less. In particular, Patent Document 5 proposes that if the sodium formate content in the sodium hydrosulfite used in the production of polycarbonate is more than 0.3 wt %, the hue of the resin will deteriorate when heated. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 4-120164 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-265766 [Patent Document 3] Special Publication No. 1-18939 [Patent Document 4] Japanese Patent Application Publication No. 7-233253 [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-096937 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the conventional techniques sometimes have the following problems. It is not possible to obtain a polyarylate resin having a sufficiently excellent color tone, and in a resin composition containing a polyarylate resin and a polyamide resin, coloration due to thermal degradation during melt molding cannot be sufficiently suppressed.

[0011] An object of the present invention is to provide a resin composition containing a polyarylate resin and a polyamide resin, which has a sufficiently good color tone of the resin composition itself and can sufficiently suppress coloration due to thermal degradation during melt molding. [Means for solving the problem]

[0012] As a result of extensive research to solve the above problem, the present inventors have found that the above object can be achieved by including an appropriate amount of a formate in a resin composition, and have arrived at the present invention.

[0013] The gist of the present invention is as follows. <1> The composition contains a polyarylate resin (A) containing an aromatic dicarboxylic acid component and a dihydric phenol component as monomer components, and a polyamide resin (B), a mass ratio (A / B) of the polyarylate resin (A) to the polyamide resin (B) is 99 / 1 to 1 / 99; A resin composition having a formate content of 0.1 to 2.0 ppm. <2> the formate salt is sodium formate; <1> The resin composition according to claim 1. <3> The resin composition has a color difference a value of -1.0 to 0.5. <1> or <2> The resin composition according to claim 1. <4> A molded plate having a thickness of 3 mm molded by injection molding the resin composition has a YI value of 15 or less. <1> ~ <3> The resin composition according to any one of the preceding claims. <5> The content of the formate is 0.1 to 0.8 ppm. <1> ~ <4> The resin composition according to any one of the preceding claims. <6> When polymerizing an aromatic dicarboxylic acid component and a dihydric phenol component, a dithionite having a formate content of 0.4 to 1.5 mass% is added in an amount of 0.05 to 4.0 mass% based on the dihydric phenol component to produce a polyarylate resin (A); Then, a polyamide resin (B) is further mixed therein. <7> The dithionite is sodium dithionite produced by the sodium formate method. <6> A method for producing the resin composition described in claim 1. <8> <1> ~ <5> Produce a resin composition according to any one of the above. <6> or <7> A method for producing the resin composition described in claim 1. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a resin composition containing a polyarylate resin and a polyamide resin, which has a sufficiently good color tone of the resin composition itself and can sufficiently suppress coloration due to thermal degradation during melt molding. DETAILED DESCRIPTION OF THE INVENTION

[0015] The resin composition of the present invention contains a polyarylate resin (A) and a polyamide resin (B).

[0016] The polyarylate resin (A) used in the present invention is an aromatic polyester resin obtained from an aromatic dicarboxylic acid component (including its derivatives) and a dihydric phenol component, and contains these components as monomer components. Therefore, the polyarylate resin (A) can also be described as containing residues of an aromatic dicarboxylic acid component and a dihydric phenol component. The structure of the polyarylate resin (A) is not particularly limited, and the present invention is applicable to polyarylate resins of any structure. The derivative refers to an organic compound in which the carboxyl group of an aromatic dicarboxylic acid is replaced with a more reactive substituent, and includes, for example, an acid halide compound having an acid halide group, as described below.

[0017] The aromatic dicarboxylic acid component for introducing the aromatic dicarboxylic acid residues constituting the polyarylate resin (A) is an organic compound containing an aromatic ring and two carboxyl groups per molecule. The carboxyl groups may be acid halide groups. An acid halide group is a group in which the hydroxyl group of a carboxyl group is substituted with a halogen atom. Specific examples of such aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, nitrophthalic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, methyl terephthalic acid, 4,4'-biphenyldicarboxylic acid, 2,2'-biphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenylisopropylidenedicarboxylic acid, 1,2-bis(4-carboxyphenoxy)ethane, 5-sodium sulfoisophthalic acid, diphenic acid, and derivatives thereof (e.g., acid halides). These aromatic dicarboxylic acids can be used alone or in combination of two or more. Among these, it is preferred that the polyarylate resin (A) contains at least one of terephthalic acid and isophthalic acid, and preferably both, from the viewpoint of further improving color tone and discoloration resistance.

[0018] In this specification, the color tone refers to the color tone of the resin composition itself, and refers to the property of having a smaller color difference a value measured by a color difference meter. Discoloration resistance is a property that more sufficiently suppresses discoloration due to thermal degradation during melt molding of a resin composition, and refers to a property that results in a smaller yellow index (YI) value of the obtained molded product as measured with a color tone measuring device.

[0019] The total content of terephthalic acid and isophthalic acid in the polyarylate resin (A) is not particularly limited, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and sufficiently preferably 100% by mass, based on the total amount of aromatic dicarboxylic acid components. The total content of terephthalic acid and isophthalic acid may be the total content of residues of terephthalic acid and isophthalic acid.

[0020] When the polyarylate resin (A) contains terephthalic acid and isophthalic acid as aromatic dicarboxylic acid components, their contents are not particularly limited, and from the viewpoint of further improving color tone and discoloration resistance, the mass ratio of terephthalic acid / isophthalic acid is preferably 0 / 100 to 100 / 0, more preferably 20 / 80 to 80 / 20, even more preferably 40 / 60 to 60 / 40, particularly preferably 45 / 55 to 55 / 45, and sufficiently preferably 50 / 50. The contents of terephthalic acid and isophthalic acid may be the contents of residues of terephthalic acid and isophthalic acid.

[0021] The dihydric phenol component for introducing the dihydric phenol residues constituting the polyarylate resin (A) is an organic compound containing two phenolic hydroxyl groups per molecule. The phenolic hydroxyl group is a hydroxyl group directly bonded to an aromatic ring. Specific examples of such dihydric phenol components include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(3-methyl-4-hydroxyphenyl)propane (bisphenol C), 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol Z), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (bisphenol AP), 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, and 2,2-bis(4-hydroxy-3,5-dibromophenyl). Examples include propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenylmethane, 4,4'-dihydroxybiphenyl [4,4'-biphenol], 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC), 4,4'-(1,3-dimethylbutylidene)diphenol, resorcinol, etc. These compounds may be used alone or in combination of two or more. From the viewpoint of further improving color tone and discoloration resistance, the polyarylate resin (A) preferably contains one or more dihydric phenol components selected from the group consisting of bisphenol A, bisphenol C, bisphenol Z, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, and bisphenol TMC, and more preferably contains bisphenol A.

[0022] The content of bisphenol A in the polyarylate resin (A) is not particularly limited, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 1 to 100 mass%, more preferably 20 to 100 mass%, even more preferably 40 to 100 mass%, particularly preferably 60 to 100 mass%, and sufficiently preferably 100 mass%, based on the total amount of dihydric phenol components. The content of bisphenol A may be the content of bisphenol A residues.

[0023] The polyarylate resin (A) may contain at least one dihydric alcohol component selected from the group consisting of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, dodecanediol, neopentyl glycol, cyclohexanediol, 1,4-dihydroxymethylcyclohexane, etc., in place of a portion of the dihydric phenol component, as long as the properties and effects of the present invention are not impaired.

[0024] The content of the dihydric alcohol component in the polyarylate resin (A) is not particularly limited and may be, for example, 50% by mass or less relative to the total amount of dihydric phenol components, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, and sufficiently preferably 0% by mass. The content of the dihydric alcohol component may be the content of residues of the dihydric alcohol component.

[0025] The polyarylate resin (A) may further contain a trifunctional or higher polyvalent monomer component, provided that the properties and effects of the present invention are not impaired. When the polyarylate resin (A) contains a trifunctional or higher polyvalent monomer component, a branched structure is introduced into the polyarylate resin (A). Examples of trifunctional or higher polyvalent monomer components include tricarboxylic acid components such as 1,3,5-benzenecarboxylic acid and triol components such as 4,4',4''-trihydroxytriphenylmethane.

[0026] The content of the polyvalent monomer component in the polyarylate resin (A) is not particularly limited and may be, for example, 20% by mass or less relative to the total amount of the dihydric phenol component and the aromatic dicarboxylic acid component, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, particularly preferably 1% by mass or less, and sufficiently preferably 0% by mass. The content of the polyvalent monomer component may be the content of residues of the polyvalent monomer component.

[0027] The polyarylate resin (A) may contain a terminal blocking agent to adjust its molecular weight. Examples of the terminal blocking agent include one or more compounds selected from the group consisting of monohydric phenols such as phenol, cresol, p-tert-butylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, and cumylphenol; monohydric acid chlorides such as benzoic acid chloride, methanesulfonyl chloride, and phenyl chloroformate; monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol; and monohydric carboxylic acids such as acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid. From the viewpoint of further improving color tone and discoloration resistance, the end-capping agent is preferably a monohydric phenol (particularly p-tert-butylphenol).

[0028] The content of the terminal blocking agent in the polyarylate resin (A) is not particularly limited, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 0.2 to 20 parts by mass, more preferably 0.6 to 10 parts by mass, still more preferably 1.2 to 6 parts by mass, and particularly preferably 2 to 5 parts by mass, relative to 100 parts by mass of the dihydric phenol component. The content of the terminal blocking agent may be the content of residues of the terminal blocking agent.

[0029] In general, from the viewpoints of mechanical properties and workability during melt molding and melt kneading, the polyarylate resin (A) preferably has an inherent viscosity of 0.40 to 1.30 dl / g, more preferably 0.45 to 1.10 dl / g, even more preferably 0.50 to 0.90 dl / g, particularly preferably 0.50 to 0.80 dl / g, and most preferably 0.50 to 0.70 dl / g.

[0030] The inherent viscosity (ηinh) is an index of molecular weight, and the value measured by the following method is used. A resin solution of polyarylate resin (A) is prepared using 1,1,2,2-tetrachloroethane as a solvent to a concentration of 1 g / dL, and the relative viscosity (ηrel) is measured at a temperature of 25°C. The inherent viscosity is calculated from the obtained relative viscosity using the following formula. ηinh(dl / g) = Ln(ηrel) / c (c: concentration)

[0031] The polymerization method for the polyarylate resin (A) is not particularly limited as long as the resulting polyarylate resin (A) has the above-mentioned properties, and may be a known method, for example, the following method: A solution polymerization method in which a dicarboxylic acid halide containing an aromatic dicarboxylic acid component is reacted with a diol containing a dihydric phenol component in an organic solvent; A melt polymerization method in which the dicarboxylic acid and the diol are heated in the presence of acetic anhydride or diallyl carbonate; and An interfacial polymerization method in which a dicarboxylic acid halide dissolved in an organic solvent that is not compatible with water is mixed with a diol dissolved in an alkaline aqueous solution.

[0032] The polymerization method for the polyarylate resin (A) used in the present invention is preferably an interfacial polymerization method, since the reaction proceeds to a high degree of polymerization at a relatively low temperature, from the viewpoint of further improving color tone and discoloration resistance.

[0033] When using the interfacial polymerization method, the organic solvent used is not particularly limited as long as it is immiscible with water and dissolves the dicarboxylic acid halide used and the resulting polyarylate resin (A). Suitable organic solvents include aliphatic chlorinated solvents such as dichloromethane, 1,2-dichloroethane, chloroform, 1,1,1-trichloroethane, and tetrachloroethane; aromatic chlorinated solvents such as chlorobenzene and o-dichlorobenzene; and mixtures thereof. In the isolation and drying process of the resulting polyarylate resin (A), it is best to avoid organic solvents with excessively high boiling points. Among these, aliphatic chlorinated solvents (especially dichloromethane) are preferred.

[0034] In the interfacial polymerization method, it is preferable to use a dithionite produced by the sodium formate method as a reducing agent, because this makes it possible to easily achieve the formate content in the resin composition described below, and as a result, to easily produce a resin composition that is excellent in color tone and discoloration resistance.

[0035] The dithionite may be an alkali metal salt of dithionous acid, such as sodium dithionite (also known as sodium hydrosulfite), potassium dithionite, etc. From the viewpoint of further improving color tone and discoloration resistance, the dithionite is preferably sodium hydrosulfite.

[0036] From the viewpoint of further improving color tone and discoloration resistance, sodium hydrosulfite produced by the sodium formate method is preferred as the dithionite. Dithionite produced by a method other than the sodium formate method (e.g., an electrolytic method) does not contain formate itself.

[0037] The sodium formate method is a method for producing sodium hydrosulfite using sodium formate. Specifically, sodium formate is dissolved in aqueous alcohol (e.g., aqueous methanol), and sodium hydroxide and sulfurous anhydride are added to cause a reaction.

[0038] The content of formate contained in the dithionite (particularly, the content of sodium formate contained in sodium hydrosulfite produced by the sodium formate method) is preferably 0.4 to 1.5 mass%, more preferably 0.4 to 1.0 mass%, even more preferably 0.5 to 1.0 mass%, and particularly preferably 0.5 to 0.8 mass%, from the viewpoint of further improving color tone and discoloration resistance. If the content of the formate (particularly, sodium formate) is too low or too high, it becomes difficult to control the formate content in the resulting polyarylate resin (A), resulting in difficulty in achieving the formate content of the resin composition described below, and discoloration due to thermal degradation during melt molding cannot be sufficiently suppressed. The content of the formate (particularly, sodium formate) is the ratio to the total amount of dithionite (particularly the total amount of sodium hydrosulfite). The total amount of dithionite refers to the total amount of dithionite and formate contained in said dithionite, and in particular, when by-products and decomposition products are contained in the dithionite, this refers to the total amount including said by-products and decomposition products. The total amount of sodium hydrosulfite refers to the total amount of sodium hydrosulfite and sodium formate contained in said sodium hydrosulfite, and in particular, when by-products and decomposition products are contained in the sodium hydrosulfite, this refers to the total amount including said by-products and decomposition products.

[0039] Methods for quantifying formate contained in dithionite (particularly methods for quantifying formate contained in sodium hydrosulfite produced by the sodium formate method) include the method specified in "Specifications and Standards for Food Additives, etc. (Ministry of Health and Welfare Notification No. 370 of 1959) Section 2: Food Additives (as of November 30, 2017)" and methods for detecting organic acids by ion chromatography. In the present invention, the method for detecting organic acids by ion chromatography is adopted.

[0040] The content of formate contained in dithionite (particularly sodium hydrosulfite) can be controlled, for example, by washing and purifying the dithionite (particularly the obtained sodium hydrosulfite) with an aqueous methanol solution. Specifically, the content of formate (particularly sodium formate) can be controlled by adjusting the number of times of washing with the aqueous methanol solution and the methanol concentration of the aqueous methanol solution. For example, the more times the washing is performed, the lower the content of formate (particularly sodium formate). On the other hand, the fewer times the washing is performed, the higher the content of formate (particularly sodium formate). Furthermore, for example, the higher the methanol concentration of the aqueous methanol solution, the lower the content of formate (particularly sodium formate). On the other hand, the lower the methanol concentration of the aqueous methanol solution, the higher the content of formate (particularly sodium formate).

[0041] From the viewpoint of further improving color tone and discoloration resistance, the amount of reducing agent (e.g., dithionite (particularly sodium hydrosulfite produced by the sodium formate method)) added is preferably 0.05 to 4.0 mass% relative to the mass of the dihydric phenol component used, more preferably 0.1 to 2.0 mass%, even more preferably 0.2 to 1.5 mass%, sufficiently preferably 0.2 to 1.1 mass%, and even sufficiently preferably 0.3 to 0.8 mass%. If the amount of reducing agent added is too small or too large, it becomes difficult to control the formate content of the polyarylate resin (A), and as a result, it becomes difficult to achieve the formate content of the resin composition described below. For example, if the amount added is less than 0.05 mass%, the effect of preventing discoloration of the dihydric phenol component is insufficient, and discoloration due to thermal degradation during melt molding cannot be sufficiently suppressed. On the other hand, if the amount added is increased to more than 4.0 mass%, the formate content of the resin composition becomes too high, and discoloration due to thermal degradation during melt molding cannot be sufficiently suppressed.

[0042] Interfacial polymerization method can use polymerization catalyst.As the polymerization catalyst of interfacial polymerization method, can be mentioned tertiary amines such as trimethylamine, triethylamine, tri-n-butylamine, tri-n-propylamine, tri-isopropylamine, trihexylamine, tridecylamine, N,N-dimethylcyclohexylamine, pyridine, quinoline, dimethylaniline; quaternary ammonium salts such as trimethylbenzylammonium halide, triethylbenzylammonium halide, tri-n-propylbenzylammonium halide, tri-n-butylbenzylammonium halide; quaternary phosphonium salts such as trimethylbenzylphosphonium halide, tetramethylbenzylphosphonium halide, triethylbenzylphosphonium halide, tri-n-butylbenzylphosphonium halide, tetra-n-butylphosphonium halide, triphenylbenzylphosphonium halide, tetraphenylphosphonium halide; crown ethers such as 18-crown-6, 18-benzocrown-6, 18-dibenzocrown-6, 15-crown-5. In particular, from the viewpoints of polymerization rate and cost, quaternary ammonium salts (particularly trimethylbenzylammonium halide and tri-n-butylbenzylammonium halide) are preferred.

[0043] The amount of the polymerization catalyst used is not particularly limited, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 0.1 to 5 mass %, more preferably 0.1 to 3 mass %, and even more preferably 0.1 to 1.5 mass % relative to the dihydric phenol component.

[0044] When producing a polyarylate resin by interfacial polymerization, it is preferable to employ the following method. A dihydric phenol component, end-capping agent, reducing agent, and polymerization catalyst are dissolved in an alkaline aqueous solution to obtain an aqueous layer. Separately, an aromatic dicarboxylic acid component is dissolved in an organic solvent to obtain an organic layer. The two incompatible liquids (the aqueous and organic layers described above) are mixed under strong stirring, and the polymerization reaction is carried out until a high degree of polymerization is achieved due to interlayer migration of the dihydric phenol component and end-capping agent component in the aqueous layer. After the reaction is complete, stirring is stopped and the resulting solution is separated into an organic layer containing the dissolved polyarylate resin and an aqueous layer containing by-products such as salts and unreacted monomers. The organic layer is then neutralized with an inorganic acid such as acetic acid or phosphoric acid.

[0045] The organic layer after neutralization contains unreacted monomers, low-molecular-weight polyarylate resins, by-product salts, and other impurities. To remove these impurities, the organic layer is thoroughly washed with pure water using a method such as static separation or centrifugation. Both static separation and centrifugation involve extracting various impurities contained in the organic layer into pure water, and either method may be used as appropriate. Washing with pure water can reduce the formate content in the polyarylate resin. Furthermore, increasing the number of times and duration of washing with pure water can further reduce the formate content.

[0046] The process of granulating polyarylate resin from the organic layer in which the thoroughly washed polyarylate resin is dissolved includes the hot water granulation method in which the organic solvent is distilled off in hot water, the kneader method in which the organic solvent is evaporated by heating using a kneader or the like and the residual polymer is pulverized, the spray dry method in which the organic solvent is sprayed with a spray to instantly evaporate the organic solvent, and the reprecipitation method in which the organic solvent solution is introduced into a poor solvent for the polyarylate resin to precipitate and precipitate the polymer component, etc. Any method may be used as appropriate, but in the present invention, the hot water granulation method is preferred in view of the properties of the particles obtained and the simplicity of the equipment.

[0047] When dichloromethane is used as the organic solvent, hot water granulation involves placing 50°C hot water in a hot water jacket tank equipped with an agitator, stirring it, and then circulating the hot water by withdrawing it from the bottom of the tank and introducing it into a wet pulverizer and returning it to the same tank, while supplying an organic solvent solution in which polyarylate resin has been dissolved.While maintaining the liquid temperature in the tank at 50°C, the organic solvent is distilled off to granulate the polyarylate resin, and a polyarylate / hot water slurry is obtained in the wet pulverizer on the circulation line, taking care not to generate large particles.This slurry is then withdrawn through a filter to obtain only the polyarylate resin powder.

[0048] The granulated polyarylate resin powder is dried using an appropriate dryer and method depending on the production volume, etc. At this time, if the drying temperature exceeds 140°C, the vaporized dichloromethane will undergo thermal decomposition, generating hydrogen chloride, which will severely corrode the inner walls of the dryer; therefore, operation at 140°C or below (particularly 120 to 135°C) is desirable. By setting the drying temperature to 120 to 135°C, it is possible to sufficiently remove moisture and dichloromethane while keeping the formate content of the polyarylate resin within the above-mentioned range.

[0049] When the polyarylate resin (A) has a powdery or granular shape (or a powdery or granular form), the particle diameter of the particles is 0.7 to 5.0 mm (some particles may be fine powder). Furthermore, the polyarylate resin (A) may contain some particles in which two or more particles are pressed together.

[0050] The particle size of the polyarylate resin (A) is a value obtained by measuring 50 random particles of the polyarylate resin (A) using a microscope (VHX-6000) manufactured by Keyence Corporation.

[0051] The polyamide resin (B) used in the present invention is not particularly limited, but is a melt-processable polymer having an amide bond formed from an aminocarboxylic acid, a lactam, or a diamine and a dicarboxylic acid. Examples of such polyamide resin (B) include polycaproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polyundecamethylene adipamide (polyamide 116), polyundecamide (polyamide 11), polydodecamide (polyamide 12), polybis(4-aminocyclohexyl)methandecamide, (polyamide P Examples of suitable polyamides include poly(3-methyl-4-aminocyclohexyl)methandodecamide (PACM12), poly(3-methyl-4-aminocyclohexyl)methandodecamide (polyamide dimethyl PACM12), poly(metaxylylene adipamide) (polyamide MXD6), poly(nonamethylene terephthalamide) (polyamide 9T), poly(decamethylene terephthalamide) (polyamide 10T), poly(undecamethylene terephthalamide) (polyamide 11T), poly(undecamethylene hexahydroterephthalamide) (polyamide 11T(H)), and copolymer polyamides and blends thereof. Among these, aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 11, polyamide 610, polyamide 10T, and blends thereof are preferred in terms of smoothness and moldability, with polyamide 6 being particularly preferred. Recycled nylon resins, such as nylon film, can also be used. The recycling method is not particularly limited, and recycled products are also preferred from the perspective of environmental considerations.

[0052] The relative viscosity of the polyamide resin (B) is not particularly limited, but from the viewpoint of the mechanical strength and moldability of the resin composition, the relative viscosity measured using 96% by mass sulfuric acid as a solvent at a temperature of 25°C and a concentration of 1 g / dL is preferably in the range of 1.5 to 5.0, and more preferably 2.0 to 4.0.

[0053] The polyamide resin (B) can be obtained as a commercially available product, or can be produced by a known method.

[0054] In the resin composition of the present invention, the mass ratio (A / B) of the polyarylate resin (A) to the polyamide resin (B) must be in the range of 99 / 1 to 1 / 99. From the viewpoint of further improving color tone and discoloration resistance, it is more preferably 90 / 10 to 10 / 90, even more preferably 80 / 20 to 20 / 80, particularly preferably 80 / 20 to 40 / 60, and most preferably 80 / 20 to 50 / 50. If the ratio of (A) to the total amount of (A) and (B) is too low, the heat resistance of the resin composition will be impaired. On the other hand, if the ratio of (A) is too high, the flowability and chemical resistance will be impaired.

[0055] The resin composition of the present invention can be produced by mixing and melt-kneading a polyarylate resin (A), a polyamide resin (B), and, if necessary, other thermoplastic resins and / or various additives to impart characteristic properties. Kneading methods include those using common extruders such as single-screw extruders, twin-screw extruders, roll mixers, and Brabender mixers. Among these, the use of a twin-screw extruder is preferred because it ensures a good kneading state of multiple raw materials. It is also preferable to use a static mixer or dynamic mixer in combination. The raw materials may be added from a hopper or a side feeder. The resin composition obtained by melt-kneading is preferably in the form of pellets. The resulting resin composition contains the resin composition of the present invention and may further contain at least one selected from other thermoplastic resins and additives. In this case, the resin composition may or may not contain the other thermoplastic resins and additives independently.

[0056] Other thermoplastic resins are resin polymers other than polyarylate resin (A) and polyamide resin (B). Examples of other thermoplastic resins include polycarbonate resin, polyester resin, polyphenylene ether resin, polystyrene resin, acrylonitrile-butadiene-styrene resin, and liquid crystal polymer. Polyester resins are polyester resins other than polyarylate resin (A).

[0057] The content of the other thermoplastic resin in the resin composition of the present invention is not particularly limited, and may be, for example, 100% by mass or less, particularly 50% by mass or less, based on the total amount of the polyarylate resin (A) and the polyamide resin (B). From the viewpoint of further improving color tone and discoloration resistance, it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less. The lower limit of the content of the other thermoplastic resin is not particularly limited, and the content of the thermoplastic resin may be 0% by mass.

[0058] As the additives, additives that may be conventionally added to polyarylate resin (A) or polyamide resin (B) can be used, such as antioxidants, lubricants, dyes and pigments, flow improvers, flame retardants, and fillers. Examples of the antioxidant include various antioxidants such as hindered phenol-based, hindered amine-based, thioether-based, and phosphorus-based antioxidants. Examples of lubricants include fatty acid salts such as stearates. Examples of dyes and pigments include metal complex dyes, anthraquinone dyes, perinone dyes, inorganic pigments such as carbon black and inorganic metals, and organic pigments containing organic compounds such as azo pigments and polycyclic pigments. Examples of flow improvers include inorganic compounds such as fatty acid salts, and organic compounds including fluorine-based and amide-based compounds. Examples of the flame retardant include various halogen-based, phosphorus-based, nitrogen-based and hydrated metal-based flame retardants. Examples of the filler include inorganic fillers such as glass fiber, glass beads, mica, talc, and silica.

[0059] The content of additives in the resin composition is not particularly limited, and may be, for example, 50% by mass or less, particularly 30% by mass or less, based on the total amount of polyarylate resin (A) and polyamide resin (B). From the viewpoint of further improving color tone and discoloration resistance, it is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, particularly preferably 1% by mass or less, sufficiently preferably 0.8% by mass or less, even sufficiently preferably 0.4% by mass or less, and most preferably 0% by mass. When two or more additives are contained, the total content thereof may be within the above range. The lower limit of the content of additives is not particularly limited, and the content of additives may be 0% by mass.

[0060] The content of antioxidant in the resin composition of the present invention is not particularly limited, but the resin composition of the present invention is sufficiently excellent in color tone and discoloration resistance even without containing an antioxidant. Therefore, the content of antioxidant may be 20% by mass or less, particularly 10% by mass or less, based on the resin composition of the present invention. From the viewpoint of further improving color tone and discoloration resistance, the content is preferably 5% by mass or less, more preferably 1% by mass or less, even more preferably 0.4% by mass or less, particularly preferably 0.2% by mass or less, and sufficiently preferably 0% by mass. When two or more antioxidants are contained, the total content thereof may be within the above range.

[0061] The resin composition of the present invention contains 0.1 to 2.0 ppm of formate. From the viewpoint of further improving color tone and discoloration resistance, the formate content is preferably 0.1 to 1.5 ppm, more preferably 0.1 to 0.8 ppm, even more preferably 0.1 to 0.5 ppm, particularly preferably 0.2 to 0.4 ppm, and most preferably 0.2 to 0.25 ppm. In the present invention, by containing the formate in the resin composition in the appropriate amount as described above, not only is the color tone of the resin composition itself sufficiently excellent, but the discoloration resistance of molded articles made from the resin composition can also be sufficiently excellent. If the formate content of the resin composition exceeds 2 ppm, thermal degradation during melt molding is accelerated, resulting in significant yellowing of molded resin articles. On the other hand, if the formate content is less than 0.1 ppm, the color difference a value of the resin composition will be very low, but the effect of suppressing thermal discoloration during melt molding will be insufficient, resulting in significant yellowing of molded articles made from the resin composition.

[0062] The formate may be an alkali metal salt of formic acid, such as sodium formate, potassium formate, etc. From the viewpoint of further improving color tone and discoloration resistance, the formate is preferably sodium formate, and the above content is preferably the content of sodium formate.

[0063] The content of formate is determined by extracting the formate from 0.5 g of the resin composition with 50 mL of ultrapure water and quantitatively analyzing the extracted formate by ion chromatography (IC).

[0064] The formate contained in the resin composition may be a residue of the formate contained in the reducing agent (e.g., dithionite (particularly sodium hydrosulfite)) used in the production of the polyarylate resin (A), or may be an additive newly added after the production of the polyarylate resin (A) or during or after the production of the resin composition.

[0065] The formate content can be controlled by the following methods: The resin composition is dissolved and washed with an organic solvent capable of dissolving the resin composition. This reduces the formate content. Various organic solvents can dissolve the resin composition depending on the resin and the monomer components that make up the resin. Examples include aliphatic chlorinated solvents such as dichloromethane, 1,2-dichloroethane, chloroform, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, dibromomethane, tribromomethane, bromoethane, 1,1-dibromoethane, and 1-bromopropane; aromatic chlorinated solvents such as chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, and p-dichlorobenzene; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; ether solvents such as 1,4-dioxane, 1,3-dioxolane, and tetrahydrofuran; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; and mixtures thereof. In the above method, the polyarylate resin (A) may be used instead of the resin composition, and may be dissolved and washed with an organic solvent in which it can be dissolved.

[0066] During the production of polyarylate resin (A), the formate content in the dithionite (particularly sodium hydrosulfite) used as a reducing agent is adjusted. For example, by reducing the formate content in the dithionite (particularly sodium hydrosulfite), the formate content in the resin composition can be reduced. Furthermore, by increasing the formate content in the dithionite (particularly sodium hydrosulfite), the formate content in the resin composition can be increased.

[0067] In producing the polyarylate resin (A), the amount of dithionite (particularly sodium hydrosulfite) used as a reducing agent is adjusted. For example, by reducing the amount of dithionite (particularly sodium hydrosulfite) used, the formate content of the resin composition can be reduced. Alternatively, by increasing the amount of dithionite (particularly sodium hydrosulfite) used, the formate content of the resin composition can be increased.

[0068] In producing the polyarylate resin (A), the formate content in the resin composition can be reduced by strengthening the washing step with pure water (for example, by extending the washing time).

[0069] When producing a resin composition, the amount of polyarylate resin used is adjusted. For example, by reducing the amount of polyarylate resin (A) used, the formate content of the resin composition can be reduced. Alternatively, for example, by increasing the amount of polyarylate resin (A) used, the formate content of the resin composition can be increased.

[0070] By employing one or more of the above-mentioned methods, or by employing two or more of them in combination, the content of formate in the resin composition can be controlled.

[0071] The color difference a value of the resin composition of the present invention is usually -1.0 to 0.5, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably -1.0 to 0.2, more preferably -1.0 to -0.1, even more preferably -1.0 to -0.4, and particularly preferably -0.8 to -0.45.

[0072] The color difference a value is obtained by filling a measurement container with a resin composition (for example, the resin composition of the present invention) so that there are no gaps, and measuring in reflection mode with a colorimetric color difference meter (for example, a colorimetric color difference meter (ZE6000) manufactured by Nippon Denshoku Industries Co., Ltd.) The resin composition used for measurement is usually in the form of pellets.

[0073] The YI value of a 3 mm thick plate obtained by injection molding the resin composition of the present invention is usually 25 or less, and from the viewpoint of further improving color tone and discoloration resistance, it is preferably 21 or less, more preferably 18 or less, even more preferably 15 or less, and particularly preferably 12 or less. There is no particular limitation on the lower limit of the YI value, and the YI value is usually 1 or more, particularly 4 or more.

[0074] The YI value is a value measured by subjecting a 3 mm thick plate obtained by injection molding a resin composition (for example, the resin composition of the present invention) at a resin temperature of 280°C using a general injection molding machine (for example, a J110AD injection molding machine manufactured by JSW Corporation) to a color measurement device (for example, an SZ-Σ90 colorimeter manufactured by Nippon Denshoku Industries Co., Ltd.). The resin composition used for molding is usually in the form of pellets. [Example]

[0075] The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples and various modifications and applications are possible within the scope of the present invention.

[0076] A. Evaluation Method (1) Quantitative determination of sodium formate in sodium hydrosulfite Approximately 0.1 g of sodium hydrosulfite was weighed into a PP container, 20 mL of ultrapure water was added, and the mixture was left to dissolve at room temperature overnight. The solution was then diluted 100 times with ultrapure water, and the diluted solution was filtered through a 0.2 μm membrane filter and quantitatively analyzed by ion chromatography (IC). A calibration curve method (multi-point calibration curve) was used for quantification.

[0077] (2) Inherent viscosity of polyarylate resin (A) A resin solution was prepared using 1,1,2,2-tetrachloroethane as a solvent to a concentration of 1 g / dl, and the relative viscosity (ηrel) was measured at a temperature of 25° C. The inherent viscosity was calculated from the obtained relative viscosity using the following formula (1). ηinh(dl / g) = Ln(ηrel) / c (c: concentration) (Equation (1))

[0078] (3) Method for quantifying residual sodium formate in a resin composition Approximately 0.5 g of the freeze-pulverized resin composition was weighed into a PP (polypropylene) container. The freeze-pulverized resin composition consisted of particles with diameters of 0.3 to 1.5 mm, including fine powder of 0.3 mm or less. The particle diameter was determined by measuring 50 randomly selected particles using a Keyence microscope (VHX-6000). Next, 50 mL of ultrapure water was added, and extraction was performed by heating in a dryer set at 120°C for 1 hour. The mixture was then filtered through a 0.2 μm membrane filter and quantitatively analyzed by ion chromatography (IC). For quantification, a calibration curve method (single-point calibration curve) was used to calculate the amount of formate ions using the following formula (2), which was then converted to the amount of sodium formate using the following formula (3).

[0079] Amount of formate ions = A × (BC) × D ÷ E ÷ F (Equation (2)) A = Concentration of calibration standard (formic acid) B = IC peak area of the analyte C = Blank IC peak area D = dilution ratio E = IC peak area of calibration standard F = sample weight to be analyzed

[0080] Sodium formate equivalent = G × H ÷ I (Equation (3)) G = amount of formate ions H = sodium formate formula weight (68.01) I = formula weight of formate ion (45.02)

[0081] (4) Color difference a value of resin composition A colorimeter (ZE6000) manufactured by Nippon Denshoku Industries Co., Ltd. was used. The resin composition pellets were packed into a measurement container so that there were no gaps, and the container was set on a sample holder, and measurement was carried out in reflection mode. Evaluation was carried out according to the following criteria. ◎◎: -0.45 or less (excellent); ◎: More than -0.45, -0.4 or less (excellent); ○: More than -0.4, less than 0.2 (good); △: Over 0.2, 0.5 or less (pass: no practical problems); ×: More than 0.5 (fail: problematic in practical use).

[0082] (5) Yellow Index (YI) Value of Injection Molded Product of Resin Composition The resin composition pellets were dried at 100°C for 8 hours, and then the resulting resin composition was molded into a 3 mm thick sample plate at a resin temperature of 280°C using a general injection molding machine (for example, a J110AD injection molding machine manufactured by JSW Corporation). The color tone was measured using a colorimeter (SZ-Σ90 type colorimeter manufactured by Nippon Denshoku Industries Co., Ltd.). Evaluation was based on the following criteria. ◎◎: 15 or less (excellent); ◎: Over 15, under 18 (excellent); ○: More than 18, less than 21 (good); △: Over 21, 25 or less (Pass: No practical problems); ×: Over 25 (failed: problematic in practical use).

[0083] B. Raw materials <Sodium hydrosulfite used in polyarylate resin (A)> Sodium hydrosulfite was prepared by the following method.

[0084] Sodium hydrosulfite A (manufacturing method: sodium formate method) (sodium formate content 0.7% by mass) and sodium hydrosulfite B (manufacturing method: sodium formate method) (sodium formate content 0.9% by mass). Sodium hydrosulfite was produced by the sodium formate method. The amount of sodium formate contained in the produced sodium hydrosulfite was quantitatively analyzed by ion chromatography (IC). The sodium formate content varied slightly depending on the production lot, and those with a sodium formate content of 0.7% by mass were designated sodium hydrosulfite A, and those with a sodium formate content of 0.9% by mass were designated sodium hydrosulfite B.

[0085] Sodium hydrosulfite C (manufacturing method: sodium formate method): sodium formate content 3.0 mass% (used in Comparative Examples 1 and 2). Sodium hydrosulfite C was produced by blending commercially available sodium formate with sodium hydrosulfite A (sodium formate content: 0.7% by mass) so that the sodium formate content was 3.0% by mass.

[0086] Sodium hydrosulfite D (manufacturing method: electrolytic method): sodium formate content 0% by mass (used in Comparative Example 5). Sodium hydrosulfite D was produced by electrolysis.

[0087] <Polyamide resin (B)> PA6: Polyamide 6 (Unitika, A1030BRL, relative viscosity 2.5) PA66: Polyamide 66 (Unitika, E2000, relative viscosity 2.8) PA10T: Polyamide 10T (Unitika, XN400, relative viscosity 2.3) PA11: Polyamide 11 (Arkema, Rilsan KNO) PA610: Polyamide 610 (Arkema, Rilsan SMVO F)

[0088] <Glass fiber> Glass fiber: (Nippon Electric Glass Co., Ltd., T-289)

[0089] Example 1 ·Method for synthesizing polyarylate resin powder A reaction vessel equipped with a stirrer was charged with 100 parts by weight of 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 3.8 parts by weight of p-tert-butylphenol, 37 parts by weight of sodium hydroxide, 0.6 parts by weight of trimethylbenzylammonium chloride, and sodium hydrosulfite A (0.5% by weight relative to the weight of the dihydric phenol component). This was dissolved in 1103 parts by weight of water to form an aqueous layer. Separately, 92 parts by weight of a 1 / 1 molar mixture of terephthalic acid chloride and isophthalic acid chloride was dissolved in 895 parts by weight of dichloromethane to form an organic layer. This organic layer was added to the previously prepared aqueous layer with vigorous stirring, and the polymerization reaction was carried out at 15°C for 2 hours. After this, the aqueous and organic layers were separated, and 10 parts by weight of acetic acid was added to the organic layer to terminate the reaction. The solution was then repeatedly washed with water until neutral, yielding a 17% by weight dichloromethane solution of polyarylate. The dichloromethane solution of polyarylate was granulated by hot water granulation, and the water and dichloromethane were thoroughly dried using a paddle-type hot air dryer at 120 to 135°C to obtain polyarylate resin granules. The particle diameter of the particles was 0.7 to 5.0 mm (some fine powder may be included).

[0090] - Manufacturing of resin compositions The obtained polyarylate resin and polycaproamide (polyamide 6) were premixed in a mass ratio of 50 / 50, and then melt-kneaded at 280°C using a twin-screw extruder with a screw diameter of 37 mm (TEM-37, manufactured by Toshiba Machine Co., Ltd.) and pelletized to obtain a resin composition of the present invention. The property values of the obtained resin composition are shown in Table 1.

[0091] Example 2 A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite A used in the polyarylate resin was added in an amount of 1.0 mass % relative to the mass of the dihydric phenol component, and p-tert-butylphenol was used in an amount of 1.6 mass parts. The property values of the obtained resin composition were as shown in Table 1.

[0092] Example 3 A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite B used in the polyarylate resin was added in an amount of 1.2 mass % relative to the mass of the dihydric phenol component, and p-tert-butylphenol was added in an amount of 1.2 parts by mass. The properties of the obtained resin composition were as shown in Table 1.

[0093] Example 4 A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite B used in the polyarylate resin was added in an amount of 3.0 mass % relative to the mass of the dihydric phenol component, and p-tert-butylphenol was added in an amount of 0.9 mass parts. The property values of the obtained resin composition were as shown in Table 1.

[0094] Example 5 A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite B used in the polyarylate resin was added in an amount of 4.5 mass % relative to the mass of the dihydric phenol component, and p-tert-butylphenol was added in an amount of 0.9 mass parts. The property values of the obtained resin composition were as shown in Table 1.

[0095] (Examples 6 to 10 and Comparative Example 6) Resin compositions were obtained in the same manner as in Example 1, except that the type of polyamide resin and the mass ratio of the resins mixed were changed as shown in Table 1. The property values of the resulting resin compositions were as shown in Table 1.

[0096] Example 11 A resin composition was obtained by carrying out the same operation as in Example 1, except that 20 parts by mass of glass fiber was blended with 100 parts by mass of the obtained resin composition. The property values of the obtained resin composition were as shown in Table 1. "100 parts by mass of the obtained resin composition" means "100 parts by mass of the resin composition obtained in Example 1," and "20 parts by mass of glass fiber" essentially means 20% by mass "with respect to the total amount of polyarylate resin (A) and polyamide resin (B)" in Example 1.

[0097] (Comparative Example 1) A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite C used in the polyarylate resin was added in an amount of 3.0 mass % relative to the mass of the dihydric phenol component. The property values of the obtained resin composition were as shown in Table 1.

[0098] (Comparative Example 2) A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite C used in the polyarylate resin was added in an amount of 0.5% by mass relative to the mass of the dihydric phenol component. The property values of the obtained resin composition were as shown in Table 1.

[0099] (Comparative Example 3) A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite B used in the polyarylate resin was added in an amount of 7.0 mass % relative to the mass of the dihydric phenol component. The property values of the obtained resin composition were as shown in Table 1.

[0100] Comparative Example 4 A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite A used in the polyarylate resin was added in an amount of 0.1 mass % relative to the mass of the dihydric phenol component. The property values of the obtained resin composition were as shown in Table 1.

[0101] (Comparative Example 5) A resin composition was obtained in the same manner as in Example 1, except that sodium hydrosulfite D used in the polyarylate resin was added in an amount of 0.5% by mass relative to the mass of the dihydric phenol component. The property values of the obtained resin composition were as shown in Table 1.

[0102] [Table 1]

[0103] The following points became clear from the above examples and comparative examples: By adding an appropriate amount of sodium formate to the resin composition, the color tone of the resin composition improves, and yellowing of molded products caused by thermal degradation due to heat melting can be more sufficiently reduced. The resin composition of the present invention can be produced by producing a polyarylate resin using a specific amount of sodium hydrosulfite having a specific sodium formate content, and then mixing and kneading the polyamide resin.

[0104] In particular, Comparative Example 5 makes it clear that even if the color tone of the resin composition itself is good, coloration due to thermal degradation during melt molding is not necessarily suppressed. [Industrial Applicability]

[0105] The resin composition of the present invention is useful in various applications requiring prevention of yellowing of molded articles, such as lamp covers and camera lenses mounted on automobiles, camera lenses mounted on mobile phones and smartphones, modules constituting electronic substrates, and as a replacement for plastic materials in parts that are primarily made of glass.

Claims

1. The composition contains a polyarylate resin (A) and a polyamide resin (B) each containing an aromatic dicarboxylic acid component and a dihydric phenol component as monomer components, a mass ratio (A / B) of the polyarylate resin (A) to the polyamide resin (B) is 99 / 1 to 1 / 99; A resin composition having a formate content of 0.1 to 2.0 ppm.

2. The resin composition according to claim 1 , wherein the formate is sodium formate.

3. The resin composition according to claim 1, wherein the resin composition has a color difference a value of -1.0 to 0.

5.

4. The resin composition according to claim 1, wherein a molded plate having a thickness of 3 mm obtained by injection molding the resin composition has a YI value of 15 or less.

5. The resin composition according to claim 1, wherein the content of the formate is 0.1 to 0.8 ppm.

6. When polymerizing an aromatic dicarboxylic acid component and a dihydric phenol component, a dithionite having a formate content of 0.4 to 1.5 mass% is added in an amount of 0.05 to 4.0 mass% based on the dihydric phenol component to produce a polyarylate resin (A); Then, the polyamide resin (B) is further mixed therein.

7. The method for producing a resin composition according to claim 6, wherein the dithionite is sodium dithionite produced by a sodium formate method.

8. The method for producing the resin composition according to claim 6, which comprises producing the resin composition according to any one of claims 1 to 5.

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