Polyarylate resin

Abstract

Provided is a polyarylate resin which has a more satisfactory color tone per se, is capable of more satisfactorily suppressing coloring due to thermal degradation during melt molding, and is capable of producing a molded article which can be used even in a reflow step (or in a high-temperature environment). The polyarylate resin contains an aromatic dicarboxylic acid component and a dihydric phenol component as monomer components, the formate content is 0.1-2.0 ppm, and the glass transition temperature is 200-300 DEG C.

Description

Technical Field

[0001] The present invention relates to a polyarylate resin and a method for producing the same. Background Art

[0002] Polyarylate resins composed of aromatic dicarboxylic acid components and diphenol components are used in various applications as amorphous, transparent, and heat-resistant resins. Among them, in the electrical and electronic fields, taking advantage of their excellent heat resistance, polyarylate resins are being studied for applications such as substrate materials that require a reflow soldering process and transparent lens applications. When performing reflow soldering treatment with lead solder, heat resistance of 250°C or higher is required, and when performing reflow soldering treatment with low-temperature solder (lead-free), heat resistance of 200°C or higher is required.

[0003] However, due to their excellent heat resistance, polyarylate resins have properties such as a high melting molding processing temperature, thermal degradation during melting, and easy coloring compared to general polymers. In addition, if the molded product is used at a high temperature for a long time, there is also a tendency to turn yellow. Therefore, their use is sometimes restricted in applications that require color tone, transparency, and no temporal color change, such as lenses for automotive lamps and cameras for in-vehicle or mobile phone mounting.

[0004] To solve the above problems, various methods of adding modifiers such as dye pigments and antioxidants during melt molding or melt kneading have been studied. For example, in Patent Document 1, a method of melt kneading dye pigments and sulfur-containing carboxylic acid esters in a polycarbonate resin is proposed. In addition, for example, in Patent Document 2, a method of melt kneading phenolic compounds, phosphorus compounds, and lactone compounds in a polyarylate resin is proposed. However, since these methods always modify using additives added during melt kneading, improvement in the color tone and thermal discoloration properties of the polyarylate resin itself is also required from the viewpoints of reducing the types and amounts of additives used.

[0005] To improve the color tone and thermal discoloration properties of the polyarylate resin itself, efforts are required at the stage of manufacturing the polyarylate resin from raw materials. As polymerization methods for polyarylate resins, melt polymerization, solution polymerization, and interfacial polymerization are known. In particular, in the interfacial polymerization method, even for polymers with high heat resistance, the reaction proceeds to a high degree of polymerization at a temperature close to room temperature, so the resulting resin has an excellent color tone. Since the transparency and heat resistance, which are the inherent characteristics of polyarylate resins, are fully utilized, it is suitable.

[0006] In addition, as shown in Patent Document 3, although not limited to the interfacial polymerization method, adding a reducing agent such as sodium dithionite in the polymerization step is effective for preventing the discoloration of the diphenol-based compound as a monomer and thus the coloring of the resulting polyarylate resin.

[0007] On the other hand, Patent Document 4 discloses a technique for manufacturing an aromatic polycarbonate excellent in hue and heat resistance by using sodium dithionite as a reducing agent added in the polymerization step.

[0008] In addition, Patent Document 5 discloses a technique for manufacturing a polycarbonate excellent in hue by making the formate contained in sodium dithionite used in the production of polycarbonate 0.3% by weight or less. In particular, in Patent Document 5, it is proposed that if the formate contained in sodium dithionite used in the production of polycarbonate is more than 0.3% by weight, the hue of the resin deteriorates when heated.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent Laid-Open No. 4-120164

[0012] Patent Document 2: Japanese Patent Laid-Open No. 2002-265766

[0013] Patent Document 3: Japanese Patent Publication No. 1-18939

[0014] Patent Document 4: Japanese Patent Laid-Open No. 7-233253

[0015] Patent Document 5: Japanese Patent Laid-Open No. 2009-096937 Summary of the Invention

[0016] However, in the prior art, the following problems sometimes occur.

[0017] · It is impossible to obtain a polyarylate resin with a sufficiently excellent hue.

[0018] · When molding using a polyarylate resin, it is impossible to sufficiently suppress the coloring caused by thermal deterioration during melt molding.

[0019] An object of the present invention is to provide a polyarylate resin having a better hue of the resin itself, capable of more sufficiently suppressing the coloring caused by thermal deterioration during melt molding, and further capable of manufacturing a molded body that can be used even in a reflow soldering process (or a high-temperature environment).

[0020] The inventors of the present invention conducted intensive studies repeatedly to solve the above problems, and as a result, found that the above object can be achieved by the polyarylate resin containing an appropriate amount of formate.

[0021] The gist of the present invention is as follows.

[0022] <1> A polyarylate resin containing an aromatic dicarboxylic acid component and a dihydric phenol component as monomer components,

[0023] The content of formate is 0.1 to 2.0 ppm, and the glass transition temperature is 200 to 300 °C.

[0024] <2> The polyarylate resin according to <1>, wherein 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane is included as the above-mentioned diphenol component.

[0025] <3> The polyarylate resin according to <1> or <2>, wherein the polyarylate resin has a color difference a value of -1.0 to 0.5.

[0026] <4> The polyarylate resin according to any one of <1> to <3>, wherein the polyarylate resin has a powdery granular shape.

[0027] <5> The polyarylate resin according to any one of <1> to <4>, wherein the above-mentioned formate is sodium formate.

[0028] <6> The polyarylate resin according to any one of <1> to <5>, wherein a molded plate with a thickness of 3 mm obtained by molding the above-mentioned polyarylate resin by injection molding has a YI value of 28 or less.

[0029] <7> The polyarylate resin according to any one of <1> to <6>, wherein the content of the above-mentioned formate is 0.1 to 1.5 ppm.

[0030] <8> A method for manufacturing a polyarylate resin, which is a method for manufacturing a polyarylate resin by polymerizing an aromatic dicarboxylic acid component and a diphenol component,

[0031] A dithionite having a formate content of 0.4 to 1.5% by mass is added to the above-mentioned diphenol component in an amount of 0.05 to 4.0% by mass.

[0032] <9> The method for manufacturing a polyarylate resin according to <8>, wherein the above-mentioned dithionite is sodium dithionite produced by the formate method.

[0033] <10> The method for manufacturing a polyarylate resin according to <8> or <9>, wherein the polyarylate resin according to any one of <1> to <7> is manufactured.

[0034] According to the present invention, it is possible to provide a polyarylate resin having heat resistance, with a more satisfactory hue of the resin itself, and capable of more sufficiently suppressing coloring caused by thermal deterioration during melt molding, and further capable of manufacturing a molded body that can be used even in a reflow soldering process (or a high-temperature environment). Detailed embodiments

[0035] The polyarylate resin of the present invention is an aromatic polyester resin obtained from an aromatic dicarboxylic acid component (including its derivatives) and a diphenol component, and contains these components as monomer components. Therefore, the polyarylate resin of the present invention can also be expressed as containing residues of an aromatic dicarboxylic acid component and a diphenol component. The structure of the polyarylate resin of the present invention is not particularly limited, and the present invention can be applied to polyarylate resins of any structure. A derivative refers to an organic compound obtained by substituting the carboxyl group of an aromatic dicarboxylic acid with a substituent having higher reactivity, and includes, for example, an acyl halide having an acyl halide group described later.

[0036] The aromatic dicarboxylic acid component for introducing the aromatic dicarboxylic acid residue constituting the polyarylate resin is an organic compound containing an aromatic ring and having two carboxyl groups per molecule. The carboxyl group can be an acyl halide group. The acyl halide group is a group formed by substituting the hydroxyl group of the carboxyl group with a halogen atom. Specific examples of such an aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, nitro phthalic 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'-diphenylether dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 4,4'-diphenylisopropylidene dicarboxylic acid, 1,2-bis(4-carboxyphenoxy)ethane, sodium 5-sulfoisophthalate, diphenic acid, and their derivatives (such as acyl halides). These aromatic dicarboxylic acids can be used alone or in combination of two or more. Among these, from the viewpoint of further improving the hue, color resistance, and heat resistance, the polyarylate resin preferably contains at least one of terephthalic acid and isophthalic acid, and preferably contains both.

[0037] In this specification, the hue is the hue of the polyarylate resin itself, and is a characteristic of having a small color difference a value measured by a colorimetric color difference meter.

[0038] Color resistance is a characteristic of more sufficiently suppressing the coloring caused by thermal deterioration during the melt molding of the polyarylate resin, and is a characteristic of having a small yellow index (YI) value measured by a hue measuring device for the obtained molded product.

[0039] Heat resistance is the heat resistance of the polyarylate resin itself, and is a characteristic of having a high glass transition temperature measured by a differential scanning calorimeter.

[0040] The total content of terephthalic acid and isophthalic acid in the polyarylate resin is not particularly limited. From the viewpoint of further improving hue, color resistance, and heat resistance, it is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol% based on the total amount of the aromatic dicarboxylic acid component. The total content of terephthalic acid and isophthalic acid may be the total content of the residues of terephthalic acid and isophthalic acid.

[0041] When the polyarylate resin contains at least one (preferably both) of terephthalic acid and isophthalic acid as the aromatic dicarboxylic acid component, their contents are not particularly limited. From the viewpoint of further improving hue, color resistance, and heat resistance, the molar ratio of terephthalic acid / isophthalic acid is preferably 0 / 100 to 100 / 0, more preferably 10 / 90 to 90 / 10, still more preferably 20 / 80 to 80 / 20, particularly preferably 40 / 60 to 60 / 40, most preferably 45 / 55 to 55 / 45, and even most preferably 50 / 50. The contents of terephthalic acid and isophthalic acid may be the contents of the residues of terephthalic acid and isophthalic acid.

[0042] The diphenol component for introducing the diphenol residue constituting the polyarylate resin 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 a diphenol component 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, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, 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, and the like. These compounds can be used alone or two or more of them can be used in combination. From the viewpoint of further improving heat resistance, the diphenol component preferably contains a diphenol component containing an aliphatic ring. The diphenol component containing an aliphatic ring is an organic compound containing one or more (especially one) aliphatic rings (such as a cyclohexane ring) per molecule, one or more (especially two) aromatic rings (such as a benzene ring) per molecule, and two phenolic hydroxyl groups per molecule. As the diphenol component containing an aliphatic ring, for example, bisphenol Z and bisphenol TMC can be cited. From the viewpoints of further improving hue, color resistance, and heat resistance, the polyarylate resin preferably contains one or more diphenol components selected from bisphenol A, bisphenol C, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, and the diphenol component containing an aliphatic ring (such as bisphenol Z and bisphenol TMC), more preferably contains one or more diphenol components selected from bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC), and from the viewpoint of further improving heat resistance, it is further preferred to contain the diphenol component containing an aliphatic ring (especially 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (bisphenol TMC)).

[0043] In the case of using a diphenol component containing an aliphatic ring (especially bisphenol TMC), from the viewpoint of maintaining good hue and color fastness while further improving heat resistance, the content of the diphenol component containing an aliphatic ring (especially bisphenol TMC) in the polyarylate resin is preferably 1 to 100 mol%, more preferably 20 to 100 mol%, still more preferably 40 to 100 mol%, particularly preferably 60 to 100 mol%, sufficiently preferably 100 mol%, based on the total amount of the diphenol component. The content of the diphenol component containing an aliphatic ring (especially bisphenol TMC) may be the content of the residue of the diphenol component containing an aliphatic ring (especially the residue of bisphenol TMC).

[0044] The total content of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC) in the polyarylate resin is not particularly limited. From the viewpoint of further improving hue, color fastness and heat resistance, it is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more, particularly preferably 95 mol% or more, sufficiently preferably 100 mol%, based on the total amount of the diphenol component. The total content of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC) may be the total content of the residues of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC).

[0045] When the polyarylate resin contains at least one of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC) as the diphenol component, their content ratios are not particularly limited. From the viewpoint of further improving hue, color fastness and heat resistance, the molar ratio of bisphenol A / the diphenol component containing an aliphatic ring (especially bisphenol TMC) is preferably 0 / 100 to 100 / 0, more preferably 0 / 100 to 95 / 5, still more preferably 0 / 100 to 80 / 20, sufficiently preferably 0 / 100 to 50 / 50, even more sufficiently preferably 0 / 100 to 40 / 60, particularly preferably 0 / 100 to 20 / 80, and most preferably 0 / 100. The content ratios of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC) may be the content ratios of the residues of bisphenol A and the diphenol component containing an aliphatic ring (especially bisphenol TMC).

[0046] From the viewpoint of further improving hue, color fastness and heat resistance, the polyarylate resin of the present invention has the following monomer composition (i) or (ii) as a more preferred embodiment, and has the following monomer composition (i) as a further preferred embodiment:

[0047] Monomer composition (i): When the polyarylate resin contains terephthalic acid and isophthalic acid in a molar ratio of terephthalic acid / isophthalic acid of 40 / 60 to 60 / 40 (especially 45 / 55 to 55 / 45), the polyarylate resin contains bisphenol A and a diol component containing an aliphatic ring (especially bisphenol TMC) in a molar ratio of bisphenol A / diol component containing an aliphatic ring of 0 / 100 to 95 / 5, preferably 0 / 100 to 80 / 20, more preferably 0 / 100 to 50 / 50, further preferably 0 / 100 to 40 / 60, sufficiently preferably 0 / 100 to 20 / 80, and even more preferably 0 / 100 to 10 / 90;

[0048] Monomer composition (ii): When the polyarylate resin contains terephthalic acid and isophthalic acid in a molar ratio of terephthalic acid / isophthalic acid of 0 / 100 or more and less than 40 / 60, or 60 / 40 or more, or less than 100 / 0, the polyarylate resin contains bisphenol A and a diol component containing an aliphatic ring (especially bisphenol TMC) in a molar ratio of bisphenol A / diol component containing an aliphatic ring of 0 / 100 to 100 / 0, more preferably 0 / 100 to 95 / 5, further preferably 0 / 100 to 80 / 20, sufficiently preferably 0 / 100 to 50 / 50, even more preferably 0 / 100 to 40 / 60, and particularly preferably 0 / 100 to 20 / 80. For example, the molar ratio of "0 / 100 or more and less than 40 / 60" means the range of 0 / 100 to 40 / 60 excluding 40 / 60.

[0049] Within the range where the properties and effects of the present invention are not impaired, the polyarylate resin may contain at least one diol component selected from ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, heptylene glycol, octylene glycol, dodecane diol, neopentyl glycol, cyclohexane diol, 1,4 - dihydroxymethylcyclohexane, etc. to replace a part of the diol component.

[0050] The content of the above diol component in the polyarylate resin is not particularly limited. For example, relative to the total amount of the diol component, it may be 50% by mass or less. From the viewpoint of further improving the hue, color resistance, and heat resistance, it is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, particularly preferably 1% by mass or less, and sufficiently preferably 0% by mass. The content of the diol component may be the content of the residue of the diol component.

[0051] The polyarylate resin may further contain a polyvalent monomer component having three or more functional groups within the range that does not impair the properties and effects of the present invention. When the polyarylate resin contains a polyvalent monomer component having three or more functional groups, a branched structure is introduced into the polyarylate resin. Examples of the polyvalent monomer component having three or more functional groups include tricarboxylic acid components such as 1,3,5-benzenetricarboxylic acid; triol components such as 4,4',4''-trihydroxytriphenylmethane.

[0052] The content of the polyvalent monomer component in the polyarylate resin is not particularly limited. For example, it may be 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 2% by mass or less, particularly preferably 1% by mass or less, and most preferably 0% by mass, based on the total amount of the diphenol component and the aromatic dicarboxylic acid component. The content of the polyvalent monomer component may be the content of the residue of the polyvalent monomer component.

[0053] When the polyarylate resin contains a terminator, the molecular weight can be adjusted. Examples of the terminator include monohydric phenols such as phenol, cresol, p-tert-butylphenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, and cumylphenol; monohydric acid chlorides such as benzoyl chloride, methanesulfonyl chloride, and phenyl chloroformate; monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecanol, stearyl alcohol, benzyl alcohol, and phenethyl alcohol; and monocarboxylic acids such as acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, tolyl acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid. From the viewpoint of further improving the hue, color resistance, and heat resistance, the terminator is preferably a monohydric phenol (especially p-tert-butylphenol).

[0054] The content of the terminator in the polyarylate resin is not particularly limited. From the viewpoint of further improving the hue, color resistance, and heat resistance, it is preferably 0.2 to 20 parts by mass, more preferably 0.6 to 10 parts by mass, further preferably 1.2 to 6 parts by mass, and particularly preferably 2 to 5 parts by mass, based on 100 parts by mass of the diphenol component. The content of the terminator may be the content of the residue of the terminator.

[0055] The polyarylate resin of the present invention contains formate in an amount of 0.1 to 2.0 ppm. From the viewpoint of further improving hue, color resistance, and heat resistance, the content of formate is preferably 0.1 to 1.5 ppm, more preferably 0.1 to 0.8 ppm, still more preferably 0.1 to 0.5 ppm, and particularly preferably 0.2 to 0.4 ppm. In the present invention, by containing an appropriate amount of formate in the polyarylate resin as described above, not only the hue of the polyarylate resin itself is sufficiently excellent, but also the color resistance of the molded article containing the polyarylate resin is sufficiently excellent. When the content of formate in the polyarylate resin exceeds 2.0 ppm, thermal deterioration during melt molding is promoted, and significant yellowing of the resin molded article occurs. On the other hand, if the content of the above formate is less than 0.1 ppm, the a value of the color difference of the powder particles becomes a very low value, but the inhibitory effect on thermal discoloration during melt molding is insufficient, and significant yellowing of the resin molded article occurs.

[0056] The formate may be an alkali metal salt of formic acid, and examples thereof include sodium formate and potassium formate. From the viewpoint of further improving hue, color resistance, and heat resistance, the formate is preferably sodium formate, and the above content is preferably the content of sodium formate.

[0057] The content of formate is determined using the value obtained by extracting formate from 0.5 g of the polyarylate resin with 50 mL of ultrapure water and quantitatively analyzing it by ion chromatography (IC).

[0058] The formate contained in the polyarylate resin of the present invention may be a residue of formate contained in a reducing agent (such as dithionite (especially sodium dithionite)) used in the production of the polyarylate resin, or may be an additive newly added after the production of the polyarylate resin.

[0059] The content of formate can be controlled by the following method;

[0060] · Dissolve and wash the polyarylate resin with an organic solvent capable of dissolving the polyarylate resin. Thereby, the content of formate can be reduced. Depending on the monomer components constituting the polyarylate resin, there are various organic solvents capable of dissolving the polyarylate resin, and examples thereof 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. alkane, 1,3-dioxolane, tetrahydrofuran, etc.; aromatic hydrocarbon solvents such as benzene, toluene, xylene, etc.; and mixtures thereof.

[0061] · When manufacturing a polyarylate resin, adjust the content of formate contained in dithionite (especially sodium dithionite) as a reducing agent. For example, if the formate content in dithionite (especially sodium dithionite) is reduced, the formate content in the polyarylate resin can be reduced. Additionally, for example, if the formate content in dithionite (especially sodium dithionite) is increased, the formate content in the polyarylate resin can be increased.

[0062] · When manufacturing a polyarylate resin, adjust the usage amount of dithionite (especially sodium dithionite) as a reducing agent. For example, if the usage amount of dithionite (especially sodium dithionite) is reduced, the formate content in the polyarylate resin can be reduced. Additionally, for example, if the usage amount of dithionite (especially sodium dithionite) is increased, the formate content in the polyarylate resin can be increased.

[0063] · When manufacturing a polyarylate resin, by strengthening the washing process using pure water (for example, extending the washing time, etc.), the formate content in the polyarylate resin can be reduced.

[0064] By adopting one or more of the above methods or by combining two or more of them, the formate content in the polyarylate resin can be controlled.

[0065] The glass transition temperature of the polyarylate resin of the present invention is 200 °C or higher. From the viewpoint of further improving hue, color resistance, and heat resistance, it is preferably 220 °C or higher, more preferably 250 °C or higher, further preferably 255 °C or higher, and particularly preferably 260 °C or higher. The upper limit value of this glass transition temperature is not particularly limited, and this glass transition temperature can generally be 300 °C or lower.

[0066] The glass transition temperature of the polyarylate resin is the starting temperature of the discontinuous change caused by the glass transition temperature in the heating curve obtained by heating from 30 °C to 400 °C at a heating rate of 10 °C / minute using a differential scanning calorimeter.

[0067] The color difference a value of the polyarylate resin of the present invention is generally -1.0 to 0.5. From the viewpoint of further improving hue, color resistance, and heat resistance, it is preferably -1.0 to 0.2, more preferably -1.0 to -0.1, further preferably -1.0 to -0.4, and particularly preferably -0.8 to -0.45.

[0068] The a value of color difference is the value obtained by measuring in the reflection mode using a color difference meter (for example, a color difference meter (ZE6000) manufactured by Nippon Denshoku Industries Co., Ltd.) with the polyarylate resin filled in the measuring container without gaps. The polyarylate resin used for measurement has a particle shape, and the particle size is 0.7 to 5.0 mm (sometimes containing a small amount of fine powder).

[0069] The YI value of a 3-mm-thick plate obtained by injection molding the polyarylate resin of the present invention is generally 28 or less, and from the viewpoints of further improving hue, color fastness, and heat resistance, it is preferably 26 or less, more preferably 24 or less, and still more preferably 20 or less. The lower limit value of the YI value is not particularly limited, and the YI value is generally 1 or more, especially 4 or more.

[0070] The YI value is the value obtained by supplying a 3-mm-thick plate obtained by injection molding the polyarylate resin at a resin temperature of 400 °C using a general injection molding machine (for example, J110AD injection molding machine manufactured by JSW Corporation) to a color tone measuring device (for example, SZ-Σ90 colorimeter manufactured by Nippon Denshoku Industries Co., Ltd.) and measuring. The polyarylate resin used for molding has a particle shape, and the particle size is 0.7 to 5.0 mm (sometimes containing a small amount of fine powder).

[0071] The inherent viscosity of the polyarylate resin of the present invention is preferably 0.40 to 1.30 dl / g, more preferably 0.45 to 1.10 dl / g, still 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, generally from the viewpoints of mechanical properties and workability during melt molding and melt kneading.

[0072] The inherent viscosity (ηinh) is an index of molecular weight, and the value obtained by the following method is used. Using 1,1,2,2-tetrachloroethane as a solvent, a resin solution of the polyarylate resin is prepared to have a concentration of 1 g / dl, and the relative viscosity (ηrel) is measured at a temperature of 25 °C. Based on the obtained relative viscosity, the inherent viscosity is calculated using the following formula.

[0073] ηinh (dl / g) = Ln(ηrel) / c (c: concentration)

[0074] Regarding the polymerization method of the polyarylate resin, as long as the obtained polyarylate resin has the above characteristic values, there is no particular limitation, and it can be a known method. For example, the following methods can be mentioned;

[0075] · Solution polymerization method, reacting a dicarboxylic acid halide containing an aromatic dicarboxylic acid component and a diol containing a bisphenol component in an organic solvent;

[0076] · The melt polymerization method, heating the above-mentioned dicarboxylic acid and diol in the presence of acetic anhydride and diallyl carbonate; and

[0077] · The interfacial polymerization method, mixing a dicarboxylic acid halide dissolved in an organic solvent immiscible with water and a diol dissolved in an alkaline aqueous solution.

[0078] From the viewpoint of further improving the hue, color fastness, and heat resistance, and since the reaction proceeds to a high degree of polymerization at a relatively low temperature, the polymerization method of the polyarylate resin used in the present invention preferably adopts the interfacial polymerization method.

[0079] In the case of applying the interfacial polymerization method, the organic solvent used is not particularly limited as long as it is immiscible with water and can dissolve the dicarboxylic acid halide used and the resulting polyarylate resin. As such organic solvents, for example, 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 are suitable. In the separation and drying process of the resulting polyarylate resin, it is preferably to avoid organic solvents with too high boiling points. As the organic solvent, among them, aliphatic chlorinated solvents (especially dichloromethane) are preferred.

[0080] In the interfacial polymerization method, as the reducing agent, a dithionite produced by the formate method is preferably used. This is because the formate content in the above-mentioned polyarylate resin can be easily achieved, and as a result, the polyarylate resin of the present invention with excellent hue and color fastness can be easily manufactured.

[0081] The dithionite may be an alkali metal salt of dithionous acid, for example, sodium dithionite (alias: Sodium Hydrosulfite), potassium dithionite, etc. From the viewpoint of further improving the hue, color fastness, and heat resistance, the dithionite is preferably sodium dithionite.

[0082] From the viewpoint of further improving the hue, color fastness, and heat resistance, the dithionite is preferably sodium dithionite produced by the formate method. The dithionite produced by a method other than the formate method (for example, the electrolysis method) itself does not contain formate.

[0083] The formate method is a method of producing sodium dithionite using formate. Specifically, it is a method of dissolving formate in a hydrous alcohol (such as hydrous methanol) and adding sodium hydroxide and anhydrous sulfurous acid to make them react.

[0084] From the viewpoint of further improving hue, color fastness, and heat resistance, the content of formate in the dithionite (particularly, the content of sodium formate in sodium dithionite produced by the sodium formate method) is preferably 0.4 to 1.5% by mass, more preferably 0.4 to 1.0% by mass, still more preferably 0.5 to 1.0% by mass, and particularly preferably 0.5 to 0.8% by mass. If the content of this formate (particularly sodium formate) is too small or too large, it is difficult for the obtained polyarylate resin to achieve the formate content of the polyarylate resin of the present invention, and coloring caused by thermal deterioration during melt molding cannot be sufficiently suppressed. The content of this formate (particularly sodium formate) is the ratio relative to the total amount of the dithionite (particularly the total amount of sodium dithionite). The total amount of the dithionite refers to the total amount of the dithionite and the formate contained in the dithionite. Particularly, when by-products and decomposition products are contained in the dithionite, it is the total amount including the by-products and decomposition products. The total amount of sodium dithionite refers to the total amount of sodium dithionite and the sodium formate contained in the sodium dithionite. Particularly, when by-products and decomposition products are contained in the sodium dithionite, it is the total amount including the by-products and decomposition products.

[0085] In the method for quantifying the formate contained in the dithionite (particularly, the method for quantifying the formate contained in sodium dithionite produced by the sodium formate method), examples include the method specified in "Standards for Food Additives, etc. (Ministry of Health and Welfare Notification No. 370 of 1969) Additive 2 (as of November 30, 2017)", the method for detecting organic acids based on ion chromatography, etc. In the present invention, the method for detecting organic acids based on ion chromatography is adopted.

[0086] The content of the formate contained in the dithionite (particularly sodium dithionite) can be controlled, for example, by washing and purifying the dithionite (particularly the obtained sodium dithionite) with an aqueous methanol solution. Specifically, by adjusting the number of washing times with the aqueous methanol solution and the methanol concentration of the aqueous methanol solution, the content of the formate (particularly sodium formate) can be controlled. For example, the more the number of washing times, the less the content of the formate (particularly sodium formate). On the other hand, the fewer the number of washing times, the more the content of the formate (particularly sodium formate). In addition, for example, the higher the methanol concentration of the aqueous methanol solution, the less the content of the formate (particularly sodium formate). On the other hand, the lower the methanol concentration of the aqueous methanol solution, the more the content of the formate (particularly sodium formate).

[0087] From the viewpoint of further improving hue, color fastness, and heat resistance, the addition amount of the reducing agent (for example, dithionite (especially sodium dithionite produced by the formate method)) is preferably 0.05 to 4.0% by mass, more preferably 0.1 to 2.0% by mass, further preferably 0.2 to 2.0% by mass, particularly preferably 0.2 to 1.5% by mass, sufficiently preferably 0.2 to 1.1% by mass, and even more sufficiently preferably 0.3 to 0.8% by mass, relative to the mass of the diphenol component used. If the addition amount of the reducing agent is too small or too large, it is difficult to achieve the formate content of the polyarylate resin of the present invention. For example, if the addition amount is less than 0.05% by mass, the effect of preventing coloring of the diphenol component is insufficient, and coloring caused by thermal deterioration during melt molding cannot be sufficiently suppressed. On the other hand, if the addition amount is increased to exceed 4.0% by mass, the formate content of the polyarylate resin of the present invention is too high, and coloring caused by thermal deterioration during melt molding cannot be sufficiently suppressed.

[0088] A polymerization catalyst can be used in the interfacial polymerization method. As the polymerization catalyst for the interfacial polymerization method, tertiary amines such as trimethylamine, triethylamine, tri-n-butylamine, tri-n-propylamine, triisopropylamine, trihexylamine, tridecylamine, N,N-dimethylcyclohexylamine, pyridine, quinoline, and dimethylaniline can be mentioned; quaternary ammonium salts such as trimethylbenzylammonium halide, triethylbenzylammonium halide, tri-n-propylbenzylammonium halide, and tri-n-butylbenzylammonium halide; trimethylbenzyl halide tetramethyl halide triethylbenzyl halide tri-n-butylbenzyl halide tetra-n-butyl halide triphenylbenzyl halide tetraphenyl halide etc. quaternary salts; crown ethers such as 18-crown-6, 18-benzo crown-6, 18-dibenzo crown-6, and 15-crown-5. Especially from the aspects of polymerization rate and price, quaternary ammonium salts (especially trimethylbenzylammonium halide and tri-n-butylbenzylammonium halide) are preferred.

[0089] The usage amount of the polymerization catalyst is not particularly limited. From the viewpoint of further improving hue, color fastness, and heat resistance, it is preferably 0.1 to 5% by mass, more preferably 0.1 to 3% by mass, and further preferably 0.1 to 1.5% by mass, relative to the diphenol component.

[0090] When producing the polyarylate resin of the present invention by the interfacial polymerization method, the following method is preferably adopted.

[0091] A water layer is obtained by dissolving a diphenol component, a capping agent, a reducing agent, and a polymerization catalyst in an alkaline aqueous solution. An organic layer is obtained by dissolving an aromatic dicarboxylic acid component in an organic solvent. The two immiscible liquids (the above-mentioned water layer and organic layer) are mixed under strong stirring, and a polymerization reaction is carried out until a high degree of polymerization is reached through the interlayer movement of the diphenol component and the capping agent component in the water layer. After the reaction is completed, the stirring is stopped, and it is separated into an organic layer in a state where the produced polyarylate resin is dissolved and a water layer in which salts, unreacted monomers, etc. as by-products are dissolved, and then the organic layer is neutralized with an inorganic acid such as acetic acid or phosphoric acid.

[0092] The neutralized organic layer contains unreacted monomers, low molecular weight substances of polyarylate resin, salts of by-products, and other impurities. In order to remove them, methods such as the static separation method and the centrifugal separation method are used to thoroughly wash the organic layer with pure water. Both the static separation method and the centrifugal separation method utilize extracting various impurities contained in the organic layer into pure water, and any method can be appropriately used. By washing with pure water, the content of formate in the polyarylate resin can be reduced. In addition, by increasing the number of washing times and the washing time with this pure water, the content of formate can be further reduced.

[0093] In the process of granulating the polyarylate resin from the organic layer in which the polyarylate resin is dissolved after sufficient washing, there are a warm water granulation method in which the organic solvent is distilled off in warm water, a kneader method in which the organic solvent is evaporated by heating with a kneader, etc. and the residual polymer is pulverized, a spray drying method in which the organic solvent is sprayed and the organic solvent is instantaneously evaporated, a reprecipitation method in which the organic solvent solution is poured into a poor solvent for the polyarylate resin to precipitate and deposit the polymer components, etc. Any method can be appropriately adopted, but in the present invention, from the viewpoints of the properties of the obtained particles, the simplicity of the device, etc., it is preferably carried out by the warm water granulation method.

[0094] When dichloromethane is used as the organic solvent, in warm water granulation, warm water at 50 °C is put into a warm water jacketed tank equipped with a stirrer, stirred, and then the warm water is drawn out from the bottom of the tank, introduced into a wet pulverizer, and returned to the same tank again. While performing the above cycle, an organic solvent solution in which the polyarylate resin is dissolved is supplied, the liquid temperature in the tank is maintained at 50 °C, and at the same time the organic solvent is distilled off to granulate the polyarylate resin. While paying attention not to generate large particles in the wet pulverizer of the circulating production line, a polyarylate / warm water slurry is obtained, and this slurry is drawn out through a filter to obtain only polyarylate resin powder particles.

[0095] The granulated polyarylate resin powder is dried by an appropriate dryer using an appropriate method according to the production volume and the like. At this time, if the drying temperature exceeds 140 °C, the vaporized dichloromethane undergoes thermal decomposition to generate hydrogen chloride, resulting in severe corrosion of the inner wall of the dryer. Therefore, it is desirable to operate at a temperature below 140 °C (especially 120 - 135 °C). By setting the drying temperature to 120 - 135 °C, the formate content of the polyarylate resin can be within the above range, and moisture and dichloromethane components can be sufficiently removed.

[0096] In the case where the polyarylate resin of the present invention has a granular shape (or powder particle form), the particle size of the particles is 0.7 - 5.0 mm (sometimes containing a small amount of fine powder). Furthermore, the polyarylate resin of the present invention may partially contain a resin formed by pressing two or more particles against each other.

[0097] The particle size of the polyarylate resin is the value obtained by measuring any 50 particles of the polyarylate resin using a microscope (VH - 6000) manufactured by Keyence Corporation.

[0098] The polyarylate resin of the present invention can be made into a polyarylate resin composition with characteristic properties by melt-kneading with various thermoplastic resins and various additives. As the kneading method, there are methods using general extruders, such as single-screw extruders, twin-screw extruders, roll kneaders, Brabender extruders, etc. Among them, the method using a twin-screw extruder has a good kneading state for multiple raw materials, so it is preferred. In addition, it is also preferred to use a static mixer and a dynamic mixer in combination. The raw materials can be added from the hopper or from the side feeder respectively. After melt-kneading, the obtained resin composition is preferably in the form of pellets. The polyarylate resin composition contains the polyarylate resin of the present invention and may further contain at least one selected from thermoplastic resins and additives. For example, the polyarylate resin composition may contain only the polyarylate resin, a thermoplastic resin, and an additive. At this time, the polyarylate resin composition may independently contain a thermoplastic resin and an additive, or may not contain them.

[0099] Examples of the thermoplastic resin include nylon resin, polycarbonate resin, polyester resin, polyphenylene ether resin, polystyrene resin, acrylonitrile-butadiene-styrene resin, liquid crystal polymer, etc. The polyester resin is a polyester resin other than the polyarylate resin of the present invention.

[0100] The content of the thermoplastic resin in the polyarylate resin composition is not particularly limited. For example, it may be 100% by mass or less, especially 50% by mass or less, relative to the polyarylate resin. From the viewpoints of further improving the hue, color resistance, and heat resistance, it is preferably 10% by mass or less, more preferably 5% by mass or less, and still more preferably 1% by mass or less. The lower limit value of the content of the thermoplastic resin is not particularly limited, and the content of the thermoplastic resin may be 0% by mass.

[0101] As additives, additives that have been conventionally added to polyarylate resins can be used. For example, antioxidants, lubricants, dye pigments, fluidity improvers, flame retardants, fillers, etc. can be cited.

[0102] As antioxidants, for example, various antioxidants such as hindered phenol-based, hindered amine-based, thioether-based, and phosphorus-based antioxidants can be cited.

[0103] As lubricants, for example, fatty acid salts represented by stearates can be cited.

[0104] As dye pigments, for example, metal complex dyes, anthraquinone-based dyes, perinone-based dyes, carbon black, inorganic pigments of inorganic metal-based, and organic pigments containing organic compounds represented by azo pigments and polycyclic pigments can be cited.

[0105] As fluidity improvers, for example, inorganic compounds such as fatty acid salts, and organic compounds containing fluorine-based and amide-based compounds can be cited.

[0106] As flame retardants, for example, various flame retardants such as halogen-based, phosphorus-based, nitrogen-based, and hydrated metal-based flame retardants can be cited.

[0107] As fillers, for example, inorganic fillers such as glass fibers, glass beads, mica, talc, and silica can be cited.

[0108] The content of the additives in the polyarylate resin composition is not particularly limited. For example, it can be 50% by mass or less, particularly 30% by mass or less, relative to the polyarylate resin. From the viewpoint of further improving the hue, color fastness, and heat resistance, it is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 1% by mass or less, particularly preferably 0.8% by mass or less, sufficiently preferably 0.4% by mass or less, and more sufficiently preferably 0% by mass. In the case of containing two or more additives, as long as their total content is within the above range. The lower limit value of the content of the additives is not particularly limited, and the content of the additives can be 0% by mass.

[0109] In particular, the content of the antioxidant in the polyarylate resin composition is not particularly limited. Even if the polyarylate resin composition of the present invention does not contain an antioxidant, the hue and color resistance are sufficiently excellent. Therefore, the content of the antioxidant in the polyarylate resin composition may be 20% by mass or less, particularly 10% by mass or less, based on the polyarylate resin. From the viewpoint of further improving the hue, color resistance, and heat resistance, it is preferably 5% by mass or less, more preferably 1% by mass or less, further preferably 0.4% by mass or less, particularly preferably 0.2% by mass or less, and most preferably 0% by mass. When two or more antioxidants are contained, as long as their total content is within the above range.

[0110] Examples

[0111] The present invention will be described in detail by way of examples, but the present invention is not limited to these examples, and various modifications and applications can be made without departing from the spirit of the present invention.

[0112] A. Evaluation method

[0113] (1) Quantitative method for sodium formate in sodium dithionite

[0114] Approximately 0.1 g of sodium dithionite was placed in a PP container and weighed, 20 mL of ultrapure water was added, and it was left to dissolve overnight at room temperature. Then, the solution was 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). For quantification, the calibration curve method (multi-point calibration curve) was used.

[0115] (2) Quantitative method for residual sodium formate in polyarylate resin powder

[0116] Approximately 0.5 g of the freeze-crushed polyarylate resin powder was placed in a PP (polypropylene) container and weighed. Regarding the shape of the freeze-crushed polyarylate resin, it was composed of particles with a particle size of 0.3 to 1.5 mm and contained fine powder with a particle size of 0.3 mm or less. It should be noted that the particle size was measured for any 50 particles using a microscope (VH-X6000) manufactured by Keyence Corporation. Then, 50 mL of ultrapure water was added, and heating extraction was performed in a dryer set at 120 °C for 1 hour. Then, it was filtered through a 0.2 μm membrane filter and quantitatively analyzed by ion chromatography (IC). For quantification, the calibration curve method (one-point calibration curve) was used, the formate ion amount was calculated according to the following formula (1), and the sodium formate content was converted using the following formula (2).

[0117] Formate ion amount = A × (B - C) × D ÷ E ÷ F (Formula (1))

[0118] A = Concentration of calibration standard sample (formic acid)

[0119] B = IC peak area of the sample to be analyzed

[0120] C = IC peak area of Blank

[0121] D = Dilution ratio

[0122] E = IC peak area of the standard sample for calibration

[0123] F = Weight of the sample to be analyzed

[0124] Amount in terms of sodium formate = G × H ÷ I (Equation (2))

[0125] G = Amount of formate ions

[0126] H = Molecular weight of sodium formate (68.01)

[0127] I = Molecular weight of formate ions (45.02)

[0128] (3) Glass transition temperature of the polyarylate resin powder

[0129] The obtained polyarylate resin powder was heated from 30 °C to 400 °C at a heating rate of 10 °C / min using a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer), and the starting temperature of the discontinuous change caused by the glass transition temperature in the obtained heating curve was taken as the glass transition temperature. Evaluation was carried out according to the following criteria.

[0130] ◎◎: 255 °C or higher (excellent);

[0131] ◎: 250 °C or higher and less than 255 °C (good);

[0132] ○: 220 °C or higher and less than 250 °C (fair);

[0133] △: 200 °C or higher and less than 220 °C (qualified: no practical problem);

[0134] ×: Less than 200 °C (unqualified: there is a practical problem).

[0135] (4) Color difference a value of the polyarylate resin powder

[0136] A color difference meter (ZE6000) manufactured by Nippon Denshoku Industries Co., Ltd. was used. The polyarylate resin powder was filled in such a way that there was no gap in the measuring container, placed on the sample stage, and measured in reflection mode. The particle size of the particles was 0.7 - 5.0 mm (sometimes containing a small amount of fine powder). Evaluation was carried out according to the following criteria.

[0137] ◎◎: -0.45 or less (excellent);

[0138] ◎: More than -0.45 and below -0.4 (excellent);

[0139] ○: More than -0.4 and below 0.2 (good);

[0140] △: More than 0.2 and below 0.5 (qualified: no problem in practice);

[0141] ×: More than 0.5 (unqualified: problem in practice).

[0142] (5) Intrinsic viscosity of polyarylate resin powder

[0143] Using 1,1,2,2 - tetrachloroethane as the solvent, prepare a resin solution with a concentration of 1 g / dl, and measure the relative viscosity (ηrel) at a temperature of 25°C. Calculate the intrinsic viscosity from the obtained relative viscosity using the following formula (3).

[0144] ηinh (dl / g) = Ln(ηrel) / c (c: concentration) (Formula (3))

[0145] (6) Yellow index (YI) value of injection molded body of polyarylate resin powder

[0146] Using a general injection molding machine (e.g., J110AD injection molding machine manufactured by JSW Corporation), mold the obtained polyarylate resin powder into a sample plate (board) with a thickness of 3 mm at a resin temperature of 360°C, and measure it using a color tone measuring device (SZ - Σ90 colorimeter manufactured by Nippon Denshoku Industries Co., Ltd.). Evaluate according to the following criteria.

[0147] ◎◎: 20 or less (excellent);

[0148] ◎: More than 20 and 24 or less (good);

[0149] ○: More than 24 and 26 or less (good);

[0150] △: More than 26 and 28 or less (qualified: no problem in practice);

[0151] ×: More than 28 (unqualified: problem in practice).

[0152] B. Raw materials

[0153] <Sodium dithionite>

[0154] Manufacture sodium dithionite by the following method.

[0155] · Sodium dithionite A (manufacturing method: formate method) (Na formate content 0.7% by mass) and sodium dithionite B (manufacturing method: formate method) (Na formate content 0.9% by mass).

[0156] Sodium dithionite is manufactured by the formate method. The amount of sodium formate contained in the manufactured sodium dithionite is quantitatively analyzed by ion chromatography (IC). The content of sodium formate varies slightly in each manufacturing batch. Sodium dithionite with a content of 0.7% by mass is designated as sodium dithionite A, and sodium dithionite with a content of 0.9% by mass is designated as sodium dithionite B.

[0157] · Sodium dithionite C (manufacturing method: formate method): Sodium formate content 3.0% by mass (used in Comparative Examples 1 and 2).

[0158] Sodium formate commercially available is mixed into sodium dithionite A (sodium formate content 0.7% by mass) to make the sodium formate content 3.0% by mass, thereby manufacturing sodium dithionite C.

[0159] · Sodium dithionite D (manufacturing method: electrolysis method): Sodium formate content 0% by mass (used in Comparative Example 5).

[0160] Sodium dithionite D is manufactured by the electrolysis method.

[0161] (Example 1)

[0162] (Synthesis method of polyarylate resin powder)

[0163] 100 parts by mass of 1,1 - bis(4 - hydroxyphenyl)-3,3,5 - trimethylcyclohexane, 1.2 parts by mass of p - tert - butylphenol, 47 parts by mass of sodium hydroxide, 2.3 parts by mass of trimethylbenzylammonium chloride, and 0.5% by mass of sodium dithionite A relative to the mass of the diphenol component are charged into a reaction vessel equipped with a stirring device and dissolved in 2304 parts by mass of water to form an aqueous layer. In addition, 66 parts by mass of a p - terephthaloyl chloride / isophthaloyl chloride = mass ratio 1 / 1 mixture is dissolved in 1424 parts by mass of dichloromethane to form an organic layer. This organic layer is added to the previously prepared aqueous layer under strong stirring, and a polymerization reaction is carried out at 15°C for 2 hours. Thereafter, the aqueous layer and the organic layer are separated, then 10 parts by mass of acetic acid is added to the organic layer to stop the reaction, and further washed repeatedly with water until it becomes neutral, obtaining a 17% by mass dichloromethane solution of polyarylate. The dichloromethane solution of polyarylate is granulated by the warm - water granulation method, and the water and dichloromethane components are sufficiently dried using a paddle - type hot - air dryer at 120 - 135°C, obtaining the polyarylate resin powder of Example 1. The particle size of these particles is 0.7 - 5.0 mm (sometimes a part contains fine powder). The other characteristic values of the obtained polyarylate resin powder are shown in Table 1.

[0164] (Example 2)

[0165] Sodium dithionite A with a mass of 1.0% by mass relative to the diphenol component was added, and p-tert-butylphenol was 2.0 parts by mass. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). The other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0166] (Example 3)

[0167] Sodium dithionite B with a mass of 1.2% by mass relative to the diphenol component was added, and p-tert-butylphenol was 0.5 parts by mass. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). The other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0168] (Example 4)

[0169] Sodium dithionite B with a mass of 3.0% by mass relative to the diphenol component was added, and p-tert-butylphenol was 0.8 parts by mass. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). The other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0170] (Examples 5 - 9)

[0171] As shown in Table 1, the feed composition was changed, and except for this, the same operation as in Example 1 was carried out to synthesize polyarylate resin. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). The other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0172] (Comparative Example 1)

[0173] Sodium dithionite C with a mass of 3.0% by mass relative to the diphenol component was added, and except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). The other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0174] (Comparative Example 2)

[0175] Sodium dithionite C was added in an amount of 0.5% by mass based on the mass of the diphenol component. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). Other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0176] (Comparative Example 3)

[0177] Sodium dithionite B was added in an amount of 7.0% by mass based on the mass of the diphenol component. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). Other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0178] (Comparative Example 4)

[0179] Sodium dithionite A was added in an amount of 0.1% by mass based on the mass of the diphenol component. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). Other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0180] (Comparative Example 5)

[0181] Sodium dithionite D was added in an amount of 0.5% by mass based on the mass of the diphenol component. Except for this, polyarylate resin powder particles were synthesized by the same method as the "Synthesis method of polyarylate resin powder particles" implemented in Example 1. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). Other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0182] (Comparative Example 6)

[0183] As shown in Table 1, the feeding composition was changed. Except for this, the same operations as in Example 1 were carried out to synthesize polyarylate resin powder particles. The particle size of the particles was 0.7 to 5.0 mm (sometimes containing a small amount of fine powder). Other characteristic values of the obtained polyarylate resin powder particles are shown in Table 1.

[0184]

[0185] It should be noted that the abbreviations in Table 1 represent the following contents respectively.

[0186] TPC: Terephthaloyl chloride

[0187] IPC: Isophthaloyl chloride

[0188] TPA: Terephthalic acid

[0189] IPA: Isophthalic acid

[0190] BisA: 2,2-Bis(4-hydroxyphenyl)propane

[0191] BisTMC: 1,1-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane

[0192] The following matters are clarified from the above-described Examples and Comparative Examples:

[0193] · By making the amount of sodium formate contained in the polyarylate resin appropriate, the hue of the polyarylate resin itself is good, and yellowing of the molded article caused by thermal deterioration during heat melting can be more sufficiently reduced, and heat resistance capable of being used in a reflow soldering process or the like can be achieved; and

[0194] · The polyarylate resin of the present invention can be produced by using sodium dithionite having a specific amount of a specific sodium formate content.

[0195] · It can be clarified from Comparative Example 5 that although the hue of the polyarylate resin itself is good, coloring caused by thermal deterioration during melt molding may not necessarily be suppressed.

[0196] · It can be clarified from Comparative Example 6 that even if the hue of the polyarylate resin itself is good and coloring caused by thermal deterioration during melt molding can be suppressed, since the heat resistance of the obtained molded body is low, it may sometimes not withstand use in a reflow soldering process or a high-temperature environment.

[0197] Industrial applicability

[0198] The polyarylate resin of the present invention is useful in various applications that require prevention of yellowing of the molded article and / or improvement of heat resistance. As such applications, for example, there can be mentioned lamp covers mounted on automobiles, camera lenses; camera lenses for mobile phones and smartphones; modules constituting electronic substrates; substitution for plastic materials of components mainly composed of glass members, etc.

Claims

1. A polyarylate resin contains an aromatic dicarboxylic acid component and a diphenol component as monomer components. The content of formate is 0.1 - 2.0 ppm, and the glass transition temperature is 200 - 300 °C.

2. The polyarylate resin according to claim 1, wherein, It contains 1,1 - bis(4 - hydroxyphenyl)-3,3,5 - trimethylcyclohexane as the diphenol component.

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

5.

4. The polyarylate resin according to claim 1, wherein, The polyarylate resin has a powdery granular shape.

5. The polyarylate resin according to claim 1, wherein, The formate is sodium formate.

6. The polyarylate resin according to claim 1, wherein, A molded plate with a thickness of 3 mm obtained by injection - molding the polyarylate resin has a YI value of 28 or less.

7. The polyarylate resin according to claim 1, wherein, The content of the formate is 0.1 - 1.5 ppm.

8. A method for manufacturing a polyarylate resin is a method for manufacturing a polyarylate resin by polymerizing an aromatic dicarboxylic acid component and a diphenol component. A sodium dithionite with a formate content of 0.4 - 1.5 mass% is added in an amount of 0.05 - 4.0 mass% relative to the diphenol component.

9. The method for producing a polyarylate resin according to claim 8, wherein, The sodium dithionite is sodium dithionite manufactured by the sodium formate method.

10. The manufacturing method of the polyarylate resin according to claim 8, wherein, Manufacture the polyarylate resin according to any one of claims 1 - 7.

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